Research Article Harmonic Impact of Plug-In Hybrid ...Daily Residential Load. A typical residential...
Transcript of Research Article Harmonic Impact of Plug-In Hybrid ...Daily Residential Load. A typical residential...
Research ArticleHarmonic Impact of Plug-In Hybrid Electric Vehicle onElectric Distribution System
A Aljanad and Azah Mohamed
Department of Electrical Electronic and Systems Engineering Universiti Kebangsaan Malaysia 43600 Bandar Baru Bangi Malaysia
Correspondence should be addressed to A Aljanad amj442gmailcom
Received 16 February 2016 Accepted 13 July 2016
Academic Editor Agostino Bruzzone
Copyright copy 2016 A Aljanad and A MohamedThis is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in anymedium provided the originalwork is properly cited
This paper presents the harmonic effects of plug-in hybrid electric vehicles (PHEV) on the IEEE 37-bus distribution system atdifferent PHEV penetration levels considering a practical daily residential load shapeThe PHEV is modeled as a current harmonicsource by using the Open-Source Distribution System Simulator (OpenDSS) and DSSimpc software Time series harmonicsimulation was conducted to investigate the harmonic impact of PHEV on the system by using harmonic data obtained from areal electric vehicle Harmonic effects on the system voltage profile and circuit power losses are also investigated by using OpenDSSand MATLAB software Currentvoltage total harmonic distortion (THD) produced from the large scale of PHEV is investigatedTest results show that the voltage and current THDs are increased up to 95 and 50 respectively due to high PHEV penetrationsand these THD values are significantly larger than the limits prescribed by the IEEE standards
1 Introduction
Currently there has been a considerable growth of plug-inhybrid electric vehicles (PHEV) integrated in electric powerdistribution systems PHEVwhich are randomly injected intoa distribution system would introduce many challenges andimpacts on the system The uncontrolled connection anddisconnection of PHEV into a power distribution systemwill increase harmonic voltage and current distortions [1 2]From the power system operation perspective the large scaleintegration of PHEV into the grid poses a real challenge Asmost of the electric vehicles are fully or partially chargedby electricity it makes them connected to the distributiongrid for considerable time duration [1] Large scale con-nection of PHEV will cause uncertainty in power systemoperation Some studies have shown that without any kindof mitigation the charging of PHEV incurs the electricitygrid with additional loads which results in increment ofaggregated load during peak hours and hence impacts theoverall reliability of the grid [2] High penetration of PHEVload can give rise to operating conditions which do not arisein traditional power systems and one of the potential issuesthat need to be addressed involves impact on power quality
which includes interruption of service variation in voltagemagnitude and harmonic distortion in voltage and current[3]Thus integration of PHEVmay have adverse effect on thedistribution network if the penetration is not carefully andsystematically planned due to the nonlinear nature of PHEVthat generate harmonics which can cause abnormal operationsuch as increased losses reduced efficiency temperature riseand premature insulation and winding failures Harmoniccurrents generated by large number of single phase electronicloads present in a distribution system can cause appreciableharmonic distortion in the grid voltage [4 5] The presenceof nonlinear electronic loads will cause increasing spectralinjectors of low order harmonic currents into the grid [4]
Many studies have been conducted related to the impactof PHEV on the grid during normal charging behavior andalso concern the uncoordinated charging behavior of PHEVwhen connected randomly in the distribution system [6ndash8] Previous studies that investigate the impact of PHEVintegration on harmonics consider area residential loadcurve In the proposed study on impact of PHEV harmoniceffects on a practical residential load shape have been exertedconsidering two cases on-peak and off-peak hours duringrapid charging In addition the impacts of PHEV on other
Hindawi Publishing CorporationModelling and Simulation in EngineeringVolume 2016 Article ID 5968943 7 pageshttpdxdoiorg10115520165968943
2 Modelling and Simulation in Engineering
R
jX(w)
GjB(w)Terminals
Series R-L
Parallel R-L
I = I fund spectrum (w)
Figure 1 PHEV model in harmonic analysis
power quality issues like voltage variation and circuit lossesare also studied considering the daily load
The aim of this study is to investigate the impact of PHEVon voltage and current harmonic distortion by performingharmonic analysis on a test system using the OpenDSS soft-ware Harmonic power flow was executed at each harmonicfrequency at the given harmonic spectrum associated withthe PHEV Due to the propagation of harmonic currentsthe harmonic voltages at all nodes in the system werethen captured In this study the baseband harmonics areconfined to well below the 15th harmonic of the fundamentalfrequency of 50Hz (850Hz) The reason for confinement ofthe harmonic voltages and currents is based on several factorsincluding the limited bandwidth of the distribution systemand also the limited harmonic content of typical distributionsystem loads
2 System Modeling
PHEV has been modeled as loads at separate individualphases to take into account the unbalanced three-phase loadsand also single phase loads are very common in distributionfeeders For other loads in the distribution system constantpower loads are considered
21 Line Model For each of the series elements a set ofequations based on the ABCD parameters have been usedThese parameters relate the sending end three-phase voltagesand currents to the receiving end three-phase voltages andcurrents for each harmonic which are given by
[119881ℎ119897119904119868ℎ119897119904
] = [119860ℎ 119861ℎ119862ℎ 119863ℎ][119881ℎ119897119903
119868ℎ119897119903
] (1)
The ABCD parameters of all the elements except the loadtap changers (LTCs) are constant In case of LTCs theseparameters depend on the tap position during the time of
operation The following equations are used to represent theA and Dmatrices for each LTC
119860ℎ119905= [[[1 + Δ119878119905tap119886119905 0 0
0 1 + Δ119878119905tap119887119905 00 0 1 + Δ119878119905tap119888119905
]]]
119863ℎ119905= 119860minusℎ119905
(2)
where Δ represents the change of time operation and tap119886119905
tap119887119905 and tap
119888119905are the tap variables with integer values
22 Constant Power Load The wye-connected constantpower loads on a per-phase basis are given as follows [7]
10038161003816100381610038161003816119868ℎ11990111987110038161003816100381610038161003816 (ang119881ℎ119901119871 minus ang119868ℎ119901119871) = 10038161003816100381610038161003816119868ℎ11990111987110038161003816100381610038161003816 ang120579ℎ119901119871 (3)
For the delta-connected loads and capacitor banks line-to-line voltages and currents are required The equations forvoltages and currents which relate line-to-line variables tophase variables are given as follows
[[[[
119881ℎ119886119887
119881ℎ119887119888
119881ℎ119888119886
]]]]= [[[1 minus1 00 1 minus1minus1 0 1
]]][[[[
119881ℎ119886
119881ℎ119887
119881ℎ119888
]]]]
[[[[
119868ℎ119886
119868ℎ119887
119868ℎ119888
]]]]= [[[1 minus1 00 1 minus1minus1 0 1
]]][[[[
119868ℎ119886119888
119868ℎ119887119886
119868ℎ119888119886
]]]]
(4)
23 Modeling of PHEV Load In this study PHEV is repre-sented as injected current harmonic source For harmonicanalysis considering current injection method PHEV loadis modeled as a Norton equivalent circuit where the currentsource represents the harmonic currents injected by nonlin-ear portion of the load Figure 1 shows a Norton equivalent
Modelling and Simulation in Engineering 3
Table 1 Line current harmonic content of PHEV charger [9]
Harmonic order Magnitude () Angle (deg)100 10000 30500300 920 12000500 6220 25500700 4180 33200900 148 357001100 708 358001300 312 284001500 048 6900
Table 2 Line current harmonic content of Nissan Leaf charger
Harmonic order Magnitude () Angle (deg)100 10000 minus2600300 2500 minus9400500 1700 minus9600700 1420 minus7200900 969 minus68001100 504 minus49001300 180 minus49001500 037 minus4600
model of a load element in OpenDSS with a combinationof series R-L and parallel R-L and the shunt admittancerepresents the linear load The linear portion of the loadprovides a damping element to harmonic propagation Thecurrent source is set to the value of fundamental current timesthe multiplier defined in the ldquospectrumrdquo object associatedwith the load for the frequency being solved The equivalentshunt admittance can be adjusted by stating the percentageof linear load that is connected as series R-L and parallel R-Lwhere 119861 and119883 are frequency dependent
The typical line harmonic current content of PHEVobtained from [8] is shown in Table 1 Another harmoniccontent acquired from the Nissan Leaf vehicle real charger isshown in Table 2
3 Harmonic Power Flow
The harmonic study involves solving for the node voltages ateach harmonic using the network equation given by
[119868ℎ] = [119884ℎ] [119881ℎ] ℎ = 1 2 119873 (5)
where 119868ℎ is the vector of source currents 119884ℎ is the nodaladmittance matrix 119881ℎ is the vector of bus voltages and ℎ isthe harmonic order
The nonlinear load is modeled as a decoupled harmonicsource that injects harmonic currents into the system Thesecurrents are initialized to proper magnitudes and phaseangles based on the fundamental power flow solution andharmonic spectrum associated with them The harmoniccurrent magnitude is assumed to be a percentage of thefundamental load current The phase relationship between
the fundamental current and nonlinear element current usedto calculate the harmonic phase angle is given by
120579ℎ = 120579ℎspectrum + ℎ (1205791 minus 1205791spectrum) (6)
where ℎ is the harmonic number 120579ℎ is the phase angle ofcurrent injected at harmonic ℎ 120579ℎspectrum is the phase anglespecified in the harmonic spectrum at harmonic ℎ 1205791 is thefundamental current phase angle and 1205791spectrum is the phaseangle displacement at fundamental frequency given in thespectrum
For the harmonic power flow calculation the decoupledharmonic power flow in OpenDSS is used At harmonicfrequencies the distribution system is modeled in the pres-ence of passive elements and harmonic current sources Therelated admittance matrix is modified in terms of harmonicfrequency Due to harmonic current injections into thesystem the nonlinear loads are modeled as current sourcesModeling of the fundamental and the ℎth harmonic currentof nonlinear load connected at node n is given by thefollowing equations
ln1119899= [119875119899 + 1198951198761198991198811
119899
]1198681119899= 119862 (ℎ) 1198681
119899
(7)
The voltage total harmonic distortion of voltage (THDV) andcurrent total harmonic distortion (THD119894) are defined as [10]
THDV = [[[(sum13ℎ=2
10038161003816100381610038161003816119881ℎ119899 100381610038161003816100381610038162)1210038161003816100381610038161198811119899 1003816100381610038161003816]]]times 100
THD119894 = [[[(sum13ℎ=2
10038161003816100381610038161003816119868ℎ119899 100381610038161003816100381610038162)1210038161003816100381610038161198681119899 1003816100381610038161003816]]]times 100
(8)
For THDV and THD119894 the applicable limit to be considered inthe study is up to 15th harmonic the harmonic orders thatcome after the 15th harmonic order are negligible
Once the conventional power flow converges harmonicpower flow mode is initialized OpenDSS implements adecoupled harmonic power flow algorithm where it buildsthe linear admittance matrix at each of the frequenciesspecified in the program and uses a direct solution to solvefor voltages and currents throughout the system at all thespecified frequencies [8]
4 Methodology
It can be said that PHEV will draw constant energy through-out the charging process Considering this important piece ofinformation in studying the impact of PHEV on a distribu-tion system PHEV can be represented by a harmonic sourceload and that harmonic analysis can be performed using timeseries analysis OpenDSS and DSSimpc software are used toperform the power flow and time series harmonic analysis
4 Modelling and Simulation in Engineering
799
722724
707
720
706
725
704
714
718
713701
702
703
705742
712
727744729
728730
731709
775
708732
736
710 734
733
735737 711738
740
741
Figure 2 IEEE 37 node test feeder
respectivelyTheMATLAB software is also used to control thepenetration of PHEV and distribute the PHEV to the nodesin a distribution system
41 Test System Description The IEEE37 test distributionsystem is modeled by using both OpenDSS and DSSimpcsoftware as shown in Figure 2 Both software types are used torun the system power flow and analyze the PHEV harmonicimpact and other power quality impact The studied systemvoltage is 48 kV and the residential network voltage is 220V
42 Daily Residential Load A typical residential power loadshape in Malaysia was used in this study as shown inFigure 3 The load profiles for a period of 24 hours with theinstantaneous power consumption given on an hourly basisare shown in the figure The off-peak time starts from 9 amto 6 pm where most of the people are not at home at thattime as depicted in the load shape and then a sudden increasetakes place after 6 pm and reaches a maximum at 8 pm andafter that gradually decreases at midnight Since Malaysia isconsidered as a hot country where consumers usually useair conditioners till late night hours high demand continuesuntil midnight
43 Vehicle Charging Time If there is no control in chargingtime most of PHEVwill be charged directly when arriving atthe location where the chargers are located Most likely whenPHEV arrives at home it will be plugged in immediatelyand start charging [10] In this case additional load fromPHEV coincides with residential load peaks This wouldexacerbate local peak load condition forcing upgrading tobe done on the infrastructures Even though additional loadis still within the capacity of the infrastructure in particulartransformer this situation will decrease transformer lifetime
3500
4000
4500
5000
5500
6000
6500
Pow
er (W
)
100
600
400
500
700
900
300
200
800
000
210
0
130
014
00
180
0
160
0
200
0
110
0
190
0
150
0
120
0
220
0
170
0
100
0
230
0
Time (hour)
Figure 3 Residential daily load of Malaysia [6]
Table 3 Limits of acceptable THDV at different voltage levels
Voltage level THDV
33KV 3011 KV 4004 KV 50
due to temperature-induced insulation aging In this studythe penetration time of the PHEV to be charged is during on-peak hours which start from 6 pm to 12 pm and graduallydecrease from 1 am to 8 am in the morning as shown inFigure 3
For the practical distribution system the voltage totalharmonic distortion (THDV) forMV is limited to 3 at 33 kV4 at 11 kV and 5 at 04 kV and below as shown in Table 3
5 Results and Discussion
The effect of harmonic current spectrum of PHEV on apractical distribution system power quality considering theresidential daily load shape of Malaysia is investigated Thepenetration level of the PHEV is gradually increased inthe system from 30 to 80 during the on-peak hours ofresidential load The different power quality issues that havebeen studied are in terms of (i) voltage profile (ii) system lossand (iii) THD
51 Voltage Profile The distribution system is subjected to30 50 and 80 injection of the PHEV and the voltageprofiles are plotted as shown in Figures 4 and 5 From thefigures the 119910-axis shows the magnitude of voltages per unitwhereas the 119909-axis shows the distance from the substationto each bus and line in kilometers The voltage profile at30 penetration is still within the accepted voltage valuesbetween 095 and 105 pu as shown in Figure 4 In contrastat 80 penetration the voltage profile is out of the acceptedvoltages as shown in Figure 5 It is clear that the heavy
Modelling and Simulation in Engineering 5
pu voltage L-N voltage profile
20 40 60 8000Distance (km)
0900
0950
1000
1050
Figure 4 Voltage profile with 30 penetration
pu voltage L-N voltage profile
20 40 60 8000Distance (km)
0900
0950
1000
1050
Figure 5 Voltage profile with 80 penetration
injection of these vehicles would affect the performance of thedistribution system voltage and would definitely introduce anew peak load in the system
52 System Loss At different penetration levels the testeddistribution percentage losses are analyzed The total powerlosses collected from the line and transformer losses ofthe test system are considered as circuit losses as shownin Figure 6 The circuit power losses in percentages arecalculated over 24 hours with no PHEVpenetration as shownin Figure 7 From the figure it is noted that the circuitpower loss percentage ranges from 48 to 89 The PHEVpenetration is gradually increased with 30 integration ofPHEV in the systemand the circuit losses percentage iswithin55 to 10 as shown in Figure 8 By further increasing thePHEV penetration to 80 the power losses increase in therange of 78 to 118 as shown in Figure 9 Thus the totalcircuit power loss is directly affected by the increase of PHEVpenetration into the distribution system
Real line losses (kWkm)
15
20
25
30
35
40
45
50
55
60
Posit
ion
valu
es (y
-axi
s)
minus80minus90 minus70 minus60minus110minus120 minus100minus130
Position values (x-axis)
2
4
6
8
10
12
SubstationLoadsService transformer
MV transformerLTCVREG
Figure 6 Circuit real power losses
Percent losses for circuit with no PHEV harmonics
Circuit lossCircuit losses (bar)
2 74 91 5 83 6 11 161514 18 241712 19 20 21 22 231310
Time (hour)
0
1
2
3
4
5
6
7
8
9
Circ
uit l
oss p
erce
ntag
e (
)
Figure 7 Total circuit power loss without PHEV penetration
Figure 10 shows a comparison of the four levels of PHEVpenetration ranging from 0 to 80The figure clearly indi-cates that the system losses increase due to PHEV harmonicswith percentage increment of losses within 9 to 102 Thelosses in the system are due to the effect of current and voltageharmonic distortions
53 Total Harmonic Distortion In this case the impact ofTHD is investigated by considering 30 harmonic injection
6 Modelling and Simulation in Engineering
Percent losses for circuit
Circuit lossCircuit losses (bar)
0
1
2
3
4
5
6
7
8
9
10
Circ
uit l
oss p
erce
ntag
e (
)
213 205 6 198 1710 1312 22 2315 1611 189742 14 241
Time (hour)
Figure 8 Total circuit power loss with 30 PHEV penetration
Percent losses for circuit with 80 PHEV harmonics
2 74 91 5 83 6 11 161514 18 241712 19 20 21 22 231310
Time (hour)
0
2
4
6
8
10
12
Circ
uit l
oss p
erce
ntag
e (
)
Circuit lossCircuit losses (bar)
Figure 9 Total circuit power loss with 80 PHEV penetration
at different nodes in the test systemThe simulation was doneconsidering 24-hour load profile with 15-minute time intervalso as to capture the harmonic effects Figure 11 shows theharmonics gradually increase with respect to the increase offrequency when it is assigned to the load in the system withmaximum harmonic distortion of 178 at 850 frequencyFigures 12 and 13 show THD119894 at two different nodes 775and 740 respectively when the PHEV are connected atoff-peak hours and on-peak hours Three different PHEVpenetrations have been considered 30 50 and 80 FromFigure 12 the maximumTHD119894 value is at phase C and at 80
Penetration levels of PHEV harmonics
Without penetration30 penetration
50 penetration80 penetration
5
6
7
8
9
10
11
12
Circ
uit l
oss p
erce
ntag
e (
)
213 205 6 198 1710 1312 22 2315 1611 189742 14 241
Time (hour)
Figure 10 Percentage circuit power losses at different PHEVpenetration levels
Monitor bus 740
100 200 300 400 500 600 700 800 9000Frequency
0
2
4
6
8
10
12
14
16
18H
arm
onic
s
Figure 11 Harmonics versus frequency
PHEV penetration level Considering the harmonic limitsspecified in the IEEE Harmonic Standard the effect of THD119894during off-peak time is acceptable when the level of PHEVpenetration is 50 However above 50 penetration levelthe THD119894 values exceed the IEEE harmonic limit Figure 13shows significant increase of THD119894 reaching 15 and 25when the PHEV penetrations are 50 and 80 respectivelyThe result shows that the maximum PHEV penetration tobe adopted is 30 in which above that value unacceptableharmonic distortions will be injected into the system
6 Conclusion
The PHEV model required for harmonic power flow studieshas been developed considering a practical residential loadshape with on-peak and off-peak periods Using the PHEVmodel the impact of PHEV on currentvoltage harmonicshas been studied considering varying levels of penetrationOther power quality issues such as total circuit power losses
Modelling and Simulation in Engineering 7
Phase APhase B
Phase C30
5080
Phases
at node 735 off-peak hours
Penetration ()
1
2
3
4
5
6
7
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Phase APhase BPhase C
Current total harmonic distortion (THDi)
Figure 12 THD119894 at node 775 with different PHEV penetrations
at node 740 on-peak hoursTotal harmonic distortion (THD)
Phase APhase B
Phase C30
5080
PhasesPenetration ()
Phase APhase BPhase C
0
5
10
15
20
25
30
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Figure 13 THD119894 at node 740 with different PHEV penetrations
and voltage profile have been investigated by increasingthe PHEV penetration in the distribution system It hasbeen observed that during off-peak time 50 of PHEVpenetration into the system is considered acceptable withno harmonic limits violated whereas during on-peak timeperiod the acceptable PHEV penetration is 30
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
Acknowledgments
The authors greatly acknowledge Universiti KebangsaanMalaysia for funding this project under Project no GUP-2014-072
References
[1] C-T Li C Ahn H Peng and J Sun ldquoIntegration of plug-in electric vehicle charging and wind energy scheduling onelectricity gridrdquo in Proceedings of the IEEE PES Innovative SmartGrid Technologies (ISGT rsquo12) pp 1ndash7 IEEE Washington DCUSA January 2012
[2] X Wang H He F Sun X Sun and H Tang ldquoComparativestudy on different energy management strategies for plug-inhybrid electric vehiclesrdquo Energies vol 6 no 11 pp 5656ndash56752013
[3] J Tan and L Wang ldquoAssessing the impact of PHEVs on loadfrequency control with high penetration of wind powerrdquo inProceedings of the IEEE PES TampD Conference and Expositionno 1 pp 1ndash5 Chicago Ill USA April 2014
[4] M Kazerooni New Load Demand for Electric Vehicles and ItsHarmonic Impacts on Power System Distribution TransformersUniversity of Windsor 2012
[5] R Singh B C Pal and R A Jabr ldquoDistribution systemstate estimation through Gaussian mixture model of the loadas pseudo-measurementrdquo IET Generation Transmission andDistribution vol 4 no 1 pp 50ndash59 2010
[6] TNB ldquoShared valuesrdquo in Electricity Supply Application Hand-book Tenaga National Berhad 2014
[7] S Paudyal C A Canizares and K Bhattacharya ldquoOptimaloperation of distribution feeders in smart gridsrdquo IEEE Trans-actions on Industrial Electronics vol 58 no 10 pp 4495ndash45032011
[8] M A S Masoum P S Moses and S Deilami ldquoLoad man-agement in smart grids considering harmonic distortion andtransformer deratingrdquo in Proceedings of the Innovative SmartGrid Technologies (ISGT rsquo10) pp 1ndash7 Gaithersburg Md USAJanuary 2010
[9] A Ul-Haq and C Cecati ldquoImpact of electric vehicles on voltageprofile and harmonics in a distribution networkrdquo in Proceedingsof the 1stWorkshop on Smart Grid and Renewable Energy (SGRErsquo15) pp 1ndash6 Doha Qatar March 2015
[10] S Srinivasaraghavan and A Khaligh ldquoTime managementrdquoIEEE Power and Energy Magazine vol 9 no 4 pp 46ndash53 2011
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2 Modelling and Simulation in Engineering
R
jX(w)
GjB(w)Terminals
Series R-L
Parallel R-L
I = I fund spectrum (w)
Figure 1 PHEV model in harmonic analysis
power quality issues like voltage variation and circuit lossesare also studied considering the daily load
The aim of this study is to investigate the impact of PHEVon voltage and current harmonic distortion by performingharmonic analysis on a test system using the OpenDSS soft-ware Harmonic power flow was executed at each harmonicfrequency at the given harmonic spectrum associated withthe PHEV Due to the propagation of harmonic currentsthe harmonic voltages at all nodes in the system werethen captured In this study the baseband harmonics areconfined to well below the 15th harmonic of the fundamentalfrequency of 50Hz (850Hz) The reason for confinement ofthe harmonic voltages and currents is based on several factorsincluding the limited bandwidth of the distribution systemand also the limited harmonic content of typical distributionsystem loads
2 System Modeling
PHEV has been modeled as loads at separate individualphases to take into account the unbalanced three-phase loadsand also single phase loads are very common in distributionfeeders For other loads in the distribution system constantpower loads are considered
21 Line Model For each of the series elements a set ofequations based on the ABCD parameters have been usedThese parameters relate the sending end three-phase voltagesand currents to the receiving end three-phase voltages andcurrents for each harmonic which are given by
[119881ℎ119897119904119868ℎ119897119904
] = [119860ℎ 119861ℎ119862ℎ 119863ℎ][119881ℎ119897119903
119868ℎ119897119903
] (1)
The ABCD parameters of all the elements except the loadtap changers (LTCs) are constant In case of LTCs theseparameters depend on the tap position during the time of
operation The following equations are used to represent theA and Dmatrices for each LTC
119860ℎ119905= [[[1 + Δ119878119905tap119886119905 0 0
0 1 + Δ119878119905tap119887119905 00 0 1 + Δ119878119905tap119888119905
]]]
119863ℎ119905= 119860minusℎ119905
(2)
where Δ represents the change of time operation and tap119886119905
tap119887119905 and tap
119888119905are the tap variables with integer values
22 Constant Power Load The wye-connected constantpower loads on a per-phase basis are given as follows [7]
10038161003816100381610038161003816119868ℎ11990111987110038161003816100381610038161003816 (ang119881ℎ119901119871 minus ang119868ℎ119901119871) = 10038161003816100381610038161003816119868ℎ11990111987110038161003816100381610038161003816 ang120579ℎ119901119871 (3)
For the delta-connected loads and capacitor banks line-to-line voltages and currents are required The equations forvoltages and currents which relate line-to-line variables tophase variables are given as follows
[[[[
119881ℎ119886119887
119881ℎ119887119888
119881ℎ119888119886
]]]]= [[[1 minus1 00 1 minus1minus1 0 1
]]][[[[
119881ℎ119886
119881ℎ119887
119881ℎ119888
]]]]
[[[[
119868ℎ119886
119868ℎ119887
119868ℎ119888
]]]]= [[[1 minus1 00 1 minus1minus1 0 1
]]][[[[
119868ℎ119886119888
119868ℎ119887119886
119868ℎ119888119886
]]]]
(4)
23 Modeling of PHEV Load In this study PHEV is repre-sented as injected current harmonic source For harmonicanalysis considering current injection method PHEV loadis modeled as a Norton equivalent circuit where the currentsource represents the harmonic currents injected by nonlin-ear portion of the load Figure 1 shows a Norton equivalent
Modelling and Simulation in Engineering 3
Table 1 Line current harmonic content of PHEV charger [9]
Harmonic order Magnitude () Angle (deg)100 10000 30500300 920 12000500 6220 25500700 4180 33200900 148 357001100 708 358001300 312 284001500 048 6900
Table 2 Line current harmonic content of Nissan Leaf charger
Harmonic order Magnitude () Angle (deg)100 10000 minus2600300 2500 minus9400500 1700 minus9600700 1420 minus7200900 969 minus68001100 504 minus49001300 180 minus49001500 037 minus4600
model of a load element in OpenDSS with a combinationof series R-L and parallel R-L and the shunt admittancerepresents the linear load The linear portion of the loadprovides a damping element to harmonic propagation Thecurrent source is set to the value of fundamental current timesthe multiplier defined in the ldquospectrumrdquo object associatedwith the load for the frequency being solved The equivalentshunt admittance can be adjusted by stating the percentageof linear load that is connected as series R-L and parallel R-Lwhere 119861 and119883 are frequency dependent
The typical line harmonic current content of PHEVobtained from [8] is shown in Table 1 Another harmoniccontent acquired from the Nissan Leaf vehicle real charger isshown in Table 2
3 Harmonic Power Flow
The harmonic study involves solving for the node voltages ateach harmonic using the network equation given by
[119868ℎ] = [119884ℎ] [119881ℎ] ℎ = 1 2 119873 (5)
where 119868ℎ is the vector of source currents 119884ℎ is the nodaladmittance matrix 119881ℎ is the vector of bus voltages and ℎ isthe harmonic order
The nonlinear load is modeled as a decoupled harmonicsource that injects harmonic currents into the system Thesecurrents are initialized to proper magnitudes and phaseangles based on the fundamental power flow solution andharmonic spectrum associated with them The harmoniccurrent magnitude is assumed to be a percentage of thefundamental load current The phase relationship between
the fundamental current and nonlinear element current usedto calculate the harmonic phase angle is given by
120579ℎ = 120579ℎspectrum + ℎ (1205791 minus 1205791spectrum) (6)
where ℎ is the harmonic number 120579ℎ is the phase angle ofcurrent injected at harmonic ℎ 120579ℎspectrum is the phase anglespecified in the harmonic spectrum at harmonic ℎ 1205791 is thefundamental current phase angle and 1205791spectrum is the phaseangle displacement at fundamental frequency given in thespectrum
For the harmonic power flow calculation the decoupledharmonic power flow in OpenDSS is used At harmonicfrequencies the distribution system is modeled in the pres-ence of passive elements and harmonic current sources Therelated admittance matrix is modified in terms of harmonicfrequency Due to harmonic current injections into thesystem the nonlinear loads are modeled as current sourcesModeling of the fundamental and the ℎth harmonic currentof nonlinear load connected at node n is given by thefollowing equations
ln1119899= [119875119899 + 1198951198761198991198811
119899
]1198681119899= 119862 (ℎ) 1198681
119899
(7)
The voltage total harmonic distortion of voltage (THDV) andcurrent total harmonic distortion (THD119894) are defined as [10]
THDV = [[[(sum13ℎ=2
10038161003816100381610038161003816119881ℎ119899 100381610038161003816100381610038162)1210038161003816100381610038161198811119899 1003816100381610038161003816]]]times 100
THD119894 = [[[(sum13ℎ=2
10038161003816100381610038161003816119868ℎ119899 100381610038161003816100381610038162)1210038161003816100381610038161198681119899 1003816100381610038161003816]]]times 100
(8)
For THDV and THD119894 the applicable limit to be considered inthe study is up to 15th harmonic the harmonic orders thatcome after the 15th harmonic order are negligible
Once the conventional power flow converges harmonicpower flow mode is initialized OpenDSS implements adecoupled harmonic power flow algorithm where it buildsthe linear admittance matrix at each of the frequenciesspecified in the program and uses a direct solution to solvefor voltages and currents throughout the system at all thespecified frequencies [8]
4 Methodology
It can be said that PHEV will draw constant energy through-out the charging process Considering this important piece ofinformation in studying the impact of PHEV on a distribu-tion system PHEV can be represented by a harmonic sourceload and that harmonic analysis can be performed using timeseries analysis OpenDSS and DSSimpc software are used toperform the power flow and time series harmonic analysis
4 Modelling and Simulation in Engineering
799
722724
707
720
706
725
704
714
718
713701
702
703
705742
712
727744729
728730
731709
775
708732
736
710 734
733
735737 711738
740
741
Figure 2 IEEE 37 node test feeder
respectivelyTheMATLAB software is also used to control thepenetration of PHEV and distribute the PHEV to the nodesin a distribution system
41 Test System Description The IEEE37 test distributionsystem is modeled by using both OpenDSS and DSSimpcsoftware as shown in Figure 2 Both software types are used torun the system power flow and analyze the PHEV harmonicimpact and other power quality impact The studied systemvoltage is 48 kV and the residential network voltage is 220V
42 Daily Residential Load A typical residential power loadshape in Malaysia was used in this study as shown inFigure 3 The load profiles for a period of 24 hours with theinstantaneous power consumption given on an hourly basisare shown in the figure The off-peak time starts from 9 amto 6 pm where most of the people are not at home at thattime as depicted in the load shape and then a sudden increasetakes place after 6 pm and reaches a maximum at 8 pm andafter that gradually decreases at midnight Since Malaysia isconsidered as a hot country where consumers usually useair conditioners till late night hours high demand continuesuntil midnight
43 Vehicle Charging Time If there is no control in chargingtime most of PHEVwill be charged directly when arriving atthe location where the chargers are located Most likely whenPHEV arrives at home it will be plugged in immediatelyand start charging [10] In this case additional load fromPHEV coincides with residential load peaks This wouldexacerbate local peak load condition forcing upgrading tobe done on the infrastructures Even though additional loadis still within the capacity of the infrastructure in particulartransformer this situation will decrease transformer lifetime
3500
4000
4500
5000
5500
6000
6500
Pow
er (W
)
100
600
400
500
700
900
300
200
800
000
210
0
130
014
00
180
0
160
0
200
0
110
0
190
0
150
0
120
0
220
0
170
0
100
0
230
0
Time (hour)
Figure 3 Residential daily load of Malaysia [6]
Table 3 Limits of acceptable THDV at different voltage levels
Voltage level THDV
33KV 3011 KV 4004 KV 50
due to temperature-induced insulation aging In this studythe penetration time of the PHEV to be charged is during on-peak hours which start from 6 pm to 12 pm and graduallydecrease from 1 am to 8 am in the morning as shown inFigure 3
For the practical distribution system the voltage totalharmonic distortion (THDV) forMV is limited to 3 at 33 kV4 at 11 kV and 5 at 04 kV and below as shown in Table 3
5 Results and Discussion
The effect of harmonic current spectrum of PHEV on apractical distribution system power quality considering theresidential daily load shape of Malaysia is investigated Thepenetration level of the PHEV is gradually increased inthe system from 30 to 80 during the on-peak hours ofresidential load The different power quality issues that havebeen studied are in terms of (i) voltage profile (ii) system lossand (iii) THD
51 Voltage Profile The distribution system is subjected to30 50 and 80 injection of the PHEV and the voltageprofiles are plotted as shown in Figures 4 and 5 From thefigures the 119910-axis shows the magnitude of voltages per unitwhereas the 119909-axis shows the distance from the substationto each bus and line in kilometers The voltage profile at30 penetration is still within the accepted voltage valuesbetween 095 and 105 pu as shown in Figure 4 In contrastat 80 penetration the voltage profile is out of the acceptedvoltages as shown in Figure 5 It is clear that the heavy
Modelling and Simulation in Engineering 5
pu voltage L-N voltage profile
20 40 60 8000Distance (km)
0900
0950
1000
1050
Figure 4 Voltage profile with 30 penetration
pu voltage L-N voltage profile
20 40 60 8000Distance (km)
0900
0950
1000
1050
Figure 5 Voltage profile with 80 penetration
injection of these vehicles would affect the performance of thedistribution system voltage and would definitely introduce anew peak load in the system
52 System Loss At different penetration levels the testeddistribution percentage losses are analyzed The total powerlosses collected from the line and transformer losses ofthe test system are considered as circuit losses as shownin Figure 6 The circuit power losses in percentages arecalculated over 24 hours with no PHEVpenetration as shownin Figure 7 From the figure it is noted that the circuitpower loss percentage ranges from 48 to 89 The PHEVpenetration is gradually increased with 30 integration ofPHEV in the systemand the circuit losses percentage iswithin55 to 10 as shown in Figure 8 By further increasing thePHEV penetration to 80 the power losses increase in therange of 78 to 118 as shown in Figure 9 Thus the totalcircuit power loss is directly affected by the increase of PHEVpenetration into the distribution system
Real line losses (kWkm)
15
20
25
30
35
40
45
50
55
60
Posit
ion
valu
es (y
-axi
s)
minus80minus90 minus70 minus60minus110minus120 minus100minus130
Position values (x-axis)
2
4
6
8
10
12
SubstationLoadsService transformer
MV transformerLTCVREG
Figure 6 Circuit real power losses
Percent losses for circuit with no PHEV harmonics
Circuit lossCircuit losses (bar)
2 74 91 5 83 6 11 161514 18 241712 19 20 21 22 231310
Time (hour)
0
1
2
3
4
5
6
7
8
9
Circ
uit l
oss p
erce
ntag
e (
)
Figure 7 Total circuit power loss without PHEV penetration
Figure 10 shows a comparison of the four levels of PHEVpenetration ranging from 0 to 80The figure clearly indi-cates that the system losses increase due to PHEV harmonicswith percentage increment of losses within 9 to 102 Thelosses in the system are due to the effect of current and voltageharmonic distortions
53 Total Harmonic Distortion In this case the impact ofTHD is investigated by considering 30 harmonic injection
6 Modelling and Simulation in Engineering
Percent losses for circuit
Circuit lossCircuit losses (bar)
0
1
2
3
4
5
6
7
8
9
10
Circ
uit l
oss p
erce
ntag
e (
)
213 205 6 198 1710 1312 22 2315 1611 189742 14 241
Time (hour)
Figure 8 Total circuit power loss with 30 PHEV penetration
Percent losses for circuit with 80 PHEV harmonics
2 74 91 5 83 6 11 161514 18 241712 19 20 21 22 231310
Time (hour)
0
2
4
6
8
10
12
Circ
uit l
oss p
erce
ntag
e (
)
Circuit lossCircuit losses (bar)
Figure 9 Total circuit power loss with 80 PHEV penetration
at different nodes in the test systemThe simulation was doneconsidering 24-hour load profile with 15-minute time intervalso as to capture the harmonic effects Figure 11 shows theharmonics gradually increase with respect to the increase offrequency when it is assigned to the load in the system withmaximum harmonic distortion of 178 at 850 frequencyFigures 12 and 13 show THD119894 at two different nodes 775and 740 respectively when the PHEV are connected atoff-peak hours and on-peak hours Three different PHEVpenetrations have been considered 30 50 and 80 FromFigure 12 the maximumTHD119894 value is at phase C and at 80
Penetration levels of PHEV harmonics
Without penetration30 penetration
50 penetration80 penetration
5
6
7
8
9
10
11
12
Circ
uit l
oss p
erce
ntag
e (
)
213 205 6 198 1710 1312 22 2315 1611 189742 14 241
Time (hour)
Figure 10 Percentage circuit power losses at different PHEVpenetration levels
Monitor bus 740
100 200 300 400 500 600 700 800 9000Frequency
0
2
4
6
8
10
12
14
16
18H
arm
onic
s
Figure 11 Harmonics versus frequency
PHEV penetration level Considering the harmonic limitsspecified in the IEEE Harmonic Standard the effect of THD119894during off-peak time is acceptable when the level of PHEVpenetration is 50 However above 50 penetration levelthe THD119894 values exceed the IEEE harmonic limit Figure 13shows significant increase of THD119894 reaching 15 and 25when the PHEV penetrations are 50 and 80 respectivelyThe result shows that the maximum PHEV penetration tobe adopted is 30 in which above that value unacceptableharmonic distortions will be injected into the system
6 Conclusion
The PHEV model required for harmonic power flow studieshas been developed considering a practical residential loadshape with on-peak and off-peak periods Using the PHEVmodel the impact of PHEV on currentvoltage harmonicshas been studied considering varying levels of penetrationOther power quality issues such as total circuit power losses
Modelling and Simulation in Engineering 7
Phase APhase B
Phase C30
5080
Phases
at node 735 off-peak hours
Penetration ()
1
2
3
4
5
6
7
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Phase APhase BPhase C
Current total harmonic distortion (THDi)
Figure 12 THD119894 at node 775 with different PHEV penetrations
at node 740 on-peak hoursTotal harmonic distortion (THD)
Phase APhase B
Phase C30
5080
PhasesPenetration ()
Phase APhase BPhase C
0
5
10
15
20
25
30
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Figure 13 THD119894 at node 740 with different PHEV penetrations
and voltage profile have been investigated by increasingthe PHEV penetration in the distribution system It hasbeen observed that during off-peak time 50 of PHEVpenetration into the system is considered acceptable withno harmonic limits violated whereas during on-peak timeperiod the acceptable PHEV penetration is 30
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
Acknowledgments
The authors greatly acknowledge Universiti KebangsaanMalaysia for funding this project under Project no GUP-2014-072
References
[1] C-T Li C Ahn H Peng and J Sun ldquoIntegration of plug-in electric vehicle charging and wind energy scheduling onelectricity gridrdquo in Proceedings of the IEEE PES Innovative SmartGrid Technologies (ISGT rsquo12) pp 1ndash7 IEEE Washington DCUSA January 2012
[2] X Wang H He F Sun X Sun and H Tang ldquoComparativestudy on different energy management strategies for plug-inhybrid electric vehiclesrdquo Energies vol 6 no 11 pp 5656ndash56752013
[3] J Tan and L Wang ldquoAssessing the impact of PHEVs on loadfrequency control with high penetration of wind powerrdquo inProceedings of the IEEE PES TampD Conference and Expositionno 1 pp 1ndash5 Chicago Ill USA April 2014
[4] M Kazerooni New Load Demand for Electric Vehicles and ItsHarmonic Impacts on Power System Distribution TransformersUniversity of Windsor 2012
[5] R Singh B C Pal and R A Jabr ldquoDistribution systemstate estimation through Gaussian mixture model of the loadas pseudo-measurementrdquo IET Generation Transmission andDistribution vol 4 no 1 pp 50ndash59 2010
[6] TNB ldquoShared valuesrdquo in Electricity Supply Application Hand-book Tenaga National Berhad 2014
[7] S Paudyal C A Canizares and K Bhattacharya ldquoOptimaloperation of distribution feeders in smart gridsrdquo IEEE Trans-actions on Industrial Electronics vol 58 no 10 pp 4495ndash45032011
[8] M A S Masoum P S Moses and S Deilami ldquoLoad man-agement in smart grids considering harmonic distortion andtransformer deratingrdquo in Proceedings of the Innovative SmartGrid Technologies (ISGT rsquo10) pp 1ndash7 Gaithersburg Md USAJanuary 2010
[9] A Ul-Haq and C Cecati ldquoImpact of electric vehicles on voltageprofile and harmonics in a distribution networkrdquo in Proceedingsof the 1stWorkshop on Smart Grid and Renewable Energy (SGRErsquo15) pp 1ndash6 Doha Qatar March 2015
[10] S Srinivasaraghavan and A Khaligh ldquoTime managementrdquoIEEE Power and Energy Magazine vol 9 no 4 pp 46ndash53 2011
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International Journal of
Modelling and Simulation in Engineering 3
Table 1 Line current harmonic content of PHEV charger [9]
Harmonic order Magnitude () Angle (deg)100 10000 30500300 920 12000500 6220 25500700 4180 33200900 148 357001100 708 358001300 312 284001500 048 6900
Table 2 Line current harmonic content of Nissan Leaf charger
Harmonic order Magnitude () Angle (deg)100 10000 minus2600300 2500 minus9400500 1700 minus9600700 1420 minus7200900 969 minus68001100 504 minus49001300 180 minus49001500 037 minus4600
model of a load element in OpenDSS with a combinationof series R-L and parallel R-L and the shunt admittancerepresents the linear load The linear portion of the loadprovides a damping element to harmonic propagation Thecurrent source is set to the value of fundamental current timesthe multiplier defined in the ldquospectrumrdquo object associatedwith the load for the frequency being solved The equivalentshunt admittance can be adjusted by stating the percentageof linear load that is connected as series R-L and parallel R-Lwhere 119861 and119883 are frequency dependent
The typical line harmonic current content of PHEVobtained from [8] is shown in Table 1 Another harmoniccontent acquired from the Nissan Leaf vehicle real charger isshown in Table 2
3 Harmonic Power Flow
The harmonic study involves solving for the node voltages ateach harmonic using the network equation given by
[119868ℎ] = [119884ℎ] [119881ℎ] ℎ = 1 2 119873 (5)
where 119868ℎ is the vector of source currents 119884ℎ is the nodaladmittance matrix 119881ℎ is the vector of bus voltages and ℎ isthe harmonic order
The nonlinear load is modeled as a decoupled harmonicsource that injects harmonic currents into the system Thesecurrents are initialized to proper magnitudes and phaseangles based on the fundamental power flow solution andharmonic spectrum associated with them The harmoniccurrent magnitude is assumed to be a percentage of thefundamental load current The phase relationship between
the fundamental current and nonlinear element current usedto calculate the harmonic phase angle is given by
120579ℎ = 120579ℎspectrum + ℎ (1205791 minus 1205791spectrum) (6)
where ℎ is the harmonic number 120579ℎ is the phase angle ofcurrent injected at harmonic ℎ 120579ℎspectrum is the phase anglespecified in the harmonic spectrum at harmonic ℎ 1205791 is thefundamental current phase angle and 1205791spectrum is the phaseangle displacement at fundamental frequency given in thespectrum
For the harmonic power flow calculation the decoupledharmonic power flow in OpenDSS is used At harmonicfrequencies the distribution system is modeled in the pres-ence of passive elements and harmonic current sources Therelated admittance matrix is modified in terms of harmonicfrequency Due to harmonic current injections into thesystem the nonlinear loads are modeled as current sourcesModeling of the fundamental and the ℎth harmonic currentof nonlinear load connected at node n is given by thefollowing equations
ln1119899= [119875119899 + 1198951198761198991198811
119899
]1198681119899= 119862 (ℎ) 1198681
119899
(7)
The voltage total harmonic distortion of voltage (THDV) andcurrent total harmonic distortion (THD119894) are defined as [10]
THDV = [[[(sum13ℎ=2
10038161003816100381610038161003816119881ℎ119899 100381610038161003816100381610038162)1210038161003816100381610038161198811119899 1003816100381610038161003816]]]times 100
THD119894 = [[[(sum13ℎ=2
10038161003816100381610038161003816119868ℎ119899 100381610038161003816100381610038162)1210038161003816100381610038161198681119899 1003816100381610038161003816]]]times 100
(8)
For THDV and THD119894 the applicable limit to be considered inthe study is up to 15th harmonic the harmonic orders thatcome after the 15th harmonic order are negligible
Once the conventional power flow converges harmonicpower flow mode is initialized OpenDSS implements adecoupled harmonic power flow algorithm where it buildsthe linear admittance matrix at each of the frequenciesspecified in the program and uses a direct solution to solvefor voltages and currents throughout the system at all thespecified frequencies [8]
4 Methodology
It can be said that PHEV will draw constant energy through-out the charging process Considering this important piece ofinformation in studying the impact of PHEV on a distribu-tion system PHEV can be represented by a harmonic sourceload and that harmonic analysis can be performed using timeseries analysis OpenDSS and DSSimpc software are used toperform the power flow and time series harmonic analysis
4 Modelling and Simulation in Engineering
799
722724
707
720
706
725
704
714
718
713701
702
703
705742
712
727744729
728730
731709
775
708732
736
710 734
733
735737 711738
740
741
Figure 2 IEEE 37 node test feeder
respectivelyTheMATLAB software is also used to control thepenetration of PHEV and distribute the PHEV to the nodesin a distribution system
41 Test System Description The IEEE37 test distributionsystem is modeled by using both OpenDSS and DSSimpcsoftware as shown in Figure 2 Both software types are used torun the system power flow and analyze the PHEV harmonicimpact and other power quality impact The studied systemvoltage is 48 kV and the residential network voltage is 220V
42 Daily Residential Load A typical residential power loadshape in Malaysia was used in this study as shown inFigure 3 The load profiles for a period of 24 hours with theinstantaneous power consumption given on an hourly basisare shown in the figure The off-peak time starts from 9 amto 6 pm where most of the people are not at home at thattime as depicted in the load shape and then a sudden increasetakes place after 6 pm and reaches a maximum at 8 pm andafter that gradually decreases at midnight Since Malaysia isconsidered as a hot country where consumers usually useair conditioners till late night hours high demand continuesuntil midnight
43 Vehicle Charging Time If there is no control in chargingtime most of PHEVwill be charged directly when arriving atthe location where the chargers are located Most likely whenPHEV arrives at home it will be plugged in immediatelyand start charging [10] In this case additional load fromPHEV coincides with residential load peaks This wouldexacerbate local peak load condition forcing upgrading tobe done on the infrastructures Even though additional loadis still within the capacity of the infrastructure in particulartransformer this situation will decrease transformer lifetime
3500
4000
4500
5000
5500
6000
6500
Pow
er (W
)
100
600
400
500
700
900
300
200
800
000
210
0
130
014
00
180
0
160
0
200
0
110
0
190
0
150
0
120
0
220
0
170
0
100
0
230
0
Time (hour)
Figure 3 Residential daily load of Malaysia [6]
Table 3 Limits of acceptable THDV at different voltage levels
Voltage level THDV
33KV 3011 KV 4004 KV 50
due to temperature-induced insulation aging In this studythe penetration time of the PHEV to be charged is during on-peak hours which start from 6 pm to 12 pm and graduallydecrease from 1 am to 8 am in the morning as shown inFigure 3
For the practical distribution system the voltage totalharmonic distortion (THDV) forMV is limited to 3 at 33 kV4 at 11 kV and 5 at 04 kV and below as shown in Table 3
5 Results and Discussion
The effect of harmonic current spectrum of PHEV on apractical distribution system power quality considering theresidential daily load shape of Malaysia is investigated Thepenetration level of the PHEV is gradually increased inthe system from 30 to 80 during the on-peak hours ofresidential load The different power quality issues that havebeen studied are in terms of (i) voltage profile (ii) system lossand (iii) THD
51 Voltage Profile The distribution system is subjected to30 50 and 80 injection of the PHEV and the voltageprofiles are plotted as shown in Figures 4 and 5 From thefigures the 119910-axis shows the magnitude of voltages per unitwhereas the 119909-axis shows the distance from the substationto each bus and line in kilometers The voltage profile at30 penetration is still within the accepted voltage valuesbetween 095 and 105 pu as shown in Figure 4 In contrastat 80 penetration the voltage profile is out of the acceptedvoltages as shown in Figure 5 It is clear that the heavy
Modelling and Simulation in Engineering 5
pu voltage L-N voltage profile
20 40 60 8000Distance (km)
0900
0950
1000
1050
Figure 4 Voltage profile with 30 penetration
pu voltage L-N voltage profile
20 40 60 8000Distance (km)
0900
0950
1000
1050
Figure 5 Voltage profile with 80 penetration
injection of these vehicles would affect the performance of thedistribution system voltage and would definitely introduce anew peak load in the system
52 System Loss At different penetration levels the testeddistribution percentage losses are analyzed The total powerlosses collected from the line and transformer losses ofthe test system are considered as circuit losses as shownin Figure 6 The circuit power losses in percentages arecalculated over 24 hours with no PHEVpenetration as shownin Figure 7 From the figure it is noted that the circuitpower loss percentage ranges from 48 to 89 The PHEVpenetration is gradually increased with 30 integration ofPHEV in the systemand the circuit losses percentage iswithin55 to 10 as shown in Figure 8 By further increasing thePHEV penetration to 80 the power losses increase in therange of 78 to 118 as shown in Figure 9 Thus the totalcircuit power loss is directly affected by the increase of PHEVpenetration into the distribution system
Real line losses (kWkm)
15
20
25
30
35
40
45
50
55
60
Posit
ion
valu
es (y
-axi
s)
minus80minus90 minus70 minus60minus110minus120 minus100minus130
Position values (x-axis)
2
4
6
8
10
12
SubstationLoadsService transformer
MV transformerLTCVREG
Figure 6 Circuit real power losses
Percent losses for circuit with no PHEV harmonics
Circuit lossCircuit losses (bar)
2 74 91 5 83 6 11 161514 18 241712 19 20 21 22 231310
Time (hour)
0
1
2
3
4
5
6
7
8
9
Circ
uit l
oss p
erce
ntag
e (
)
Figure 7 Total circuit power loss without PHEV penetration
Figure 10 shows a comparison of the four levels of PHEVpenetration ranging from 0 to 80The figure clearly indi-cates that the system losses increase due to PHEV harmonicswith percentage increment of losses within 9 to 102 Thelosses in the system are due to the effect of current and voltageharmonic distortions
53 Total Harmonic Distortion In this case the impact ofTHD is investigated by considering 30 harmonic injection
6 Modelling and Simulation in Engineering
Percent losses for circuit
Circuit lossCircuit losses (bar)
0
1
2
3
4
5
6
7
8
9
10
Circ
uit l
oss p
erce
ntag
e (
)
213 205 6 198 1710 1312 22 2315 1611 189742 14 241
Time (hour)
Figure 8 Total circuit power loss with 30 PHEV penetration
Percent losses for circuit with 80 PHEV harmonics
2 74 91 5 83 6 11 161514 18 241712 19 20 21 22 231310
Time (hour)
0
2
4
6
8
10
12
Circ
uit l
oss p
erce
ntag
e (
)
Circuit lossCircuit losses (bar)
Figure 9 Total circuit power loss with 80 PHEV penetration
at different nodes in the test systemThe simulation was doneconsidering 24-hour load profile with 15-minute time intervalso as to capture the harmonic effects Figure 11 shows theharmonics gradually increase with respect to the increase offrequency when it is assigned to the load in the system withmaximum harmonic distortion of 178 at 850 frequencyFigures 12 and 13 show THD119894 at two different nodes 775and 740 respectively when the PHEV are connected atoff-peak hours and on-peak hours Three different PHEVpenetrations have been considered 30 50 and 80 FromFigure 12 the maximumTHD119894 value is at phase C and at 80
Penetration levels of PHEV harmonics
Without penetration30 penetration
50 penetration80 penetration
5
6
7
8
9
10
11
12
Circ
uit l
oss p
erce
ntag
e (
)
213 205 6 198 1710 1312 22 2315 1611 189742 14 241
Time (hour)
Figure 10 Percentage circuit power losses at different PHEVpenetration levels
Monitor bus 740
100 200 300 400 500 600 700 800 9000Frequency
0
2
4
6
8
10
12
14
16
18H
arm
onic
s
Figure 11 Harmonics versus frequency
PHEV penetration level Considering the harmonic limitsspecified in the IEEE Harmonic Standard the effect of THD119894during off-peak time is acceptable when the level of PHEVpenetration is 50 However above 50 penetration levelthe THD119894 values exceed the IEEE harmonic limit Figure 13shows significant increase of THD119894 reaching 15 and 25when the PHEV penetrations are 50 and 80 respectivelyThe result shows that the maximum PHEV penetration tobe adopted is 30 in which above that value unacceptableharmonic distortions will be injected into the system
6 Conclusion
The PHEV model required for harmonic power flow studieshas been developed considering a practical residential loadshape with on-peak and off-peak periods Using the PHEVmodel the impact of PHEV on currentvoltage harmonicshas been studied considering varying levels of penetrationOther power quality issues such as total circuit power losses
Modelling and Simulation in Engineering 7
Phase APhase B
Phase C30
5080
Phases
at node 735 off-peak hours
Penetration ()
1
2
3
4
5
6
7
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Phase APhase BPhase C
Current total harmonic distortion (THDi)
Figure 12 THD119894 at node 775 with different PHEV penetrations
at node 740 on-peak hoursTotal harmonic distortion (THD)
Phase APhase B
Phase C30
5080
PhasesPenetration ()
Phase APhase BPhase C
0
5
10
15
20
25
30
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Figure 13 THD119894 at node 740 with different PHEV penetrations
and voltage profile have been investigated by increasingthe PHEV penetration in the distribution system It hasbeen observed that during off-peak time 50 of PHEVpenetration into the system is considered acceptable withno harmonic limits violated whereas during on-peak timeperiod the acceptable PHEV penetration is 30
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
Acknowledgments
The authors greatly acknowledge Universiti KebangsaanMalaysia for funding this project under Project no GUP-2014-072
References
[1] C-T Li C Ahn H Peng and J Sun ldquoIntegration of plug-in electric vehicle charging and wind energy scheduling onelectricity gridrdquo in Proceedings of the IEEE PES Innovative SmartGrid Technologies (ISGT rsquo12) pp 1ndash7 IEEE Washington DCUSA January 2012
[2] X Wang H He F Sun X Sun and H Tang ldquoComparativestudy on different energy management strategies for plug-inhybrid electric vehiclesrdquo Energies vol 6 no 11 pp 5656ndash56752013
[3] J Tan and L Wang ldquoAssessing the impact of PHEVs on loadfrequency control with high penetration of wind powerrdquo inProceedings of the IEEE PES TampD Conference and Expositionno 1 pp 1ndash5 Chicago Ill USA April 2014
[4] M Kazerooni New Load Demand for Electric Vehicles and ItsHarmonic Impacts on Power System Distribution TransformersUniversity of Windsor 2012
[5] R Singh B C Pal and R A Jabr ldquoDistribution systemstate estimation through Gaussian mixture model of the loadas pseudo-measurementrdquo IET Generation Transmission andDistribution vol 4 no 1 pp 50ndash59 2010
[6] TNB ldquoShared valuesrdquo in Electricity Supply Application Hand-book Tenaga National Berhad 2014
[7] S Paudyal C A Canizares and K Bhattacharya ldquoOptimaloperation of distribution feeders in smart gridsrdquo IEEE Trans-actions on Industrial Electronics vol 58 no 10 pp 4495ndash45032011
[8] M A S Masoum P S Moses and S Deilami ldquoLoad man-agement in smart grids considering harmonic distortion andtransformer deratingrdquo in Proceedings of the Innovative SmartGrid Technologies (ISGT rsquo10) pp 1ndash7 Gaithersburg Md USAJanuary 2010
[9] A Ul-Haq and C Cecati ldquoImpact of electric vehicles on voltageprofile and harmonics in a distribution networkrdquo in Proceedingsof the 1stWorkshop on Smart Grid and Renewable Energy (SGRErsquo15) pp 1ndash6 Doha Qatar March 2015
[10] S Srinivasaraghavan and A Khaligh ldquoTime managementrdquoIEEE Power and Energy Magazine vol 9 no 4 pp 46ndash53 2011
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
4 Modelling and Simulation in Engineering
799
722724
707
720
706
725
704
714
718
713701
702
703
705742
712
727744729
728730
731709
775
708732
736
710 734
733
735737 711738
740
741
Figure 2 IEEE 37 node test feeder
respectivelyTheMATLAB software is also used to control thepenetration of PHEV and distribute the PHEV to the nodesin a distribution system
41 Test System Description The IEEE37 test distributionsystem is modeled by using both OpenDSS and DSSimpcsoftware as shown in Figure 2 Both software types are used torun the system power flow and analyze the PHEV harmonicimpact and other power quality impact The studied systemvoltage is 48 kV and the residential network voltage is 220V
42 Daily Residential Load A typical residential power loadshape in Malaysia was used in this study as shown inFigure 3 The load profiles for a period of 24 hours with theinstantaneous power consumption given on an hourly basisare shown in the figure The off-peak time starts from 9 amto 6 pm where most of the people are not at home at thattime as depicted in the load shape and then a sudden increasetakes place after 6 pm and reaches a maximum at 8 pm andafter that gradually decreases at midnight Since Malaysia isconsidered as a hot country where consumers usually useair conditioners till late night hours high demand continuesuntil midnight
43 Vehicle Charging Time If there is no control in chargingtime most of PHEVwill be charged directly when arriving atthe location where the chargers are located Most likely whenPHEV arrives at home it will be plugged in immediatelyand start charging [10] In this case additional load fromPHEV coincides with residential load peaks This wouldexacerbate local peak load condition forcing upgrading tobe done on the infrastructures Even though additional loadis still within the capacity of the infrastructure in particulartransformer this situation will decrease transformer lifetime
3500
4000
4500
5000
5500
6000
6500
Pow
er (W
)
100
600
400
500
700
900
300
200
800
000
210
0
130
014
00
180
0
160
0
200
0
110
0
190
0
150
0
120
0
220
0
170
0
100
0
230
0
Time (hour)
Figure 3 Residential daily load of Malaysia [6]
Table 3 Limits of acceptable THDV at different voltage levels
Voltage level THDV
33KV 3011 KV 4004 KV 50
due to temperature-induced insulation aging In this studythe penetration time of the PHEV to be charged is during on-peak hours which start from 6 pm to 12 pm and graduallydecrease from 1 am to 8 am in the morning as shown inFigure 3
For the practical distribution system the voltage totalharmonic distortion (THDV) forMV is limited to 3 at 33 kV4 at 11 kV and 5 at 04 kV and below as shown in Table 3
5 Results and Discussion
The effect of harmonic current spectrum of PHEV on apractical distribution system power quality considering theresidential daily load shape of Malaysia is investigated Thepenetration level of the PHEV is gradually increased inthe system from 30 to 80 during the on-peak hours ofresidential load The different power quality issues that havebeen studied are in terms of (i) voltage profile (ii) system lossand (iii) THD
51 Voltage Profile The distribution system is subjected to30 50 and 80 injection of the PHEV and the voltageprofiles are plotted as shown in Figures 4 and 5 From thefigures the 119910-axis shows the magnitude of voltages per unitwhereas the 119909-axis shows the distance from the substationto each bus and line in kilometers The voltage profile at30 penetration is still within the accepted voltage valuesbetween 095 and 105 pu as shown in Figure 4 In contrastat 80 penetration the voltage profile is out of the acceptedvoltages as shown in Figure 5 It is clear that the heavy
Modelling and Simulation in Engineering 5
pu voltage L-N voltage profile
20 40 60 8000Distance (km)
0900
0950
1000
1050
Figure 4 Voltage profile with 30 penetration
pu voltage L-N voltage profile
20 40 60 8000Distance (km)
0900
0950
1000
1050
Figure 5 Voltage profile with 80 penetration
injection of these vehicles would affect the performance of thedistribution system voltage and would definitely introduce anew peak load in the system
52 System Loss At different penetration levels the testeddistribution percentage losses are analyzed The total powerlosses collected from the line and transformer losses ofthe test system are considered as circuit losses as shownin Figure 6 The circuit power losses in percentages arecalculated over 24 hours with no PHEVpenetration as shownin Figure 7 From the figure it is noted that the circuitpower loss percentage ranges from 48 to 89 The PHEVpenetration is gradually increased with 30 integration ofPHEV in the systemand the circuit losses percentage iswithin55 to 10 as shown in Figure 8 By further increasing thePHEV penetration to 80 the power losses increase in therange of 78 to 118 as shown in Figure 9 Thus the totalcircuit power loss is directly affected by the increase of PHEVpenetration into the distribution system
Real line losses (kWkm)
15
20
25
30
35
40
45
50
55
60
Posit
ion
valu
es (y
-axi
s)
minus80minus90 minus70 minus60minus110minus120 minus100minus130
Position values (x-axis)
2
4
6
8
10
12
SubstationLoadsService transformer
MV transformerLTCVREG
Figure 6 Circuit real power losses
Percent losses for circuit with no PHEV harmonics
Circuit lossCircuit losses (bar)
2 74 91 5 83 6 11 161514 18 241712 19 20 21 22 231310
Time (hour)
0
1
2
3
4
5
6
7
8
9
Circ
uit l
oss p
erce
ntag
e (
)
Figure 7 Total circuit power loss without PHEV penetration
Figure 10 shows a comparison of the four levels of PHEVpenetration ranging from 0 to 80The figure clearly indi-cates that the system losses increase due to PHEV harmonicswith percentage increment of losses within 9 to 102 Thelosses in the system are due to the effect of current and voltageharmonic distortions
53 Total Harmonic Distortion In this case the impact ofTHD is investigated by considering 30 harmonic injection
6 Modelling and Simulation in Engineering
Percent losses for circuit
Circuit lossCircuit losses (bar)
0
1
2
3
4
5
6
7
8
9
10
Circ
uit l
oss p
erce
ntag
e (
)
213 205 6 198 1710 1312 22 2315 1611 189742 14 241
Time (hour)
Figure 8 Total circuit power loss with 30 PHEV penetration
Percent losses for circuit with 80 PHEV harmonics
2 74 91 5 83 6 11 161514 18 241712 19 20 21 22 231310
Time (hour)
0
2
4
6
8
10
12
Circ
uit l
oss p
erce
ntag
e (
)
Circuit lossCircuit losses (bar)
Figure 9 Total circuit power loss with 80 PHEV penetration
at different nodes in the test systemThe simulation was doneconsidering 24-hour load profile with 15-minute time intervalso as to capture the harmonic effects Figure 11 shows theharmonics gradually increase with respect to the increase offrequency when it is assigned to the load in the system withmaximum harmonic distortion of 178 at 850 frequencyFigures 12 and 13 show THD119894 at two different nodes 775and 740 respectively when the PHEV are connected atoff-peak hours and on-peak hours Three different PHEVpenetrations have been considered 30 50 and 80 FromFigure 12 the maximumTHD119894 value is at phase C and at 80
Penetration levels of PHEV harmonics
Without penetration30 penetration
50 penetration80 penetration
5
6
7
8
9
10
11
12
Circ
uit l
oss p
erce
ntag
e (
)
213 205 6 198 1710 1312 22 2315 1611 189742 14 241
Time (hour)
Figure 10 Percentage circuit power losses at different PHEVpenetration levels
Monitor bus 740
100 200 300 400 500 600 700 800 9000Frequency
0
2
4
6
8
10
12
14
16
18H
arm
onic
s
Figure 11 Harmonics versus frequency
PHEV penetration level Considering the harmonic limitsspecified in the IEEE Harmonic Standard the effect of THD119894during off-peak time is acceptable when the level of PHEVpenetration is 50 However above 50 penetration levelthe THD119894 values exceed the IEEE harmonic limit Figure 13shows significant increase of THD119894 reaching 15 and 25when the PHEV penetrations are 50 and 80 respectivelyThe result shows that the maximum PHEV penetration tobe adopted is 30 in which above that value unacceptableharmonic distortions will be injected into the system
6 Conclusion
The PHEV model required for harmonic power flow studieshas been developed considering a practical residential loadshape with on-peak and off-peak periods Using the PHEVmodel the impact of PHEV on currentvoltage harmonicshas been studied considering varying levels of penetrationOther power quality issues such as total circuit power losses
Modelling and Simulation in Engineering 7
Phase APhase B
Phase C30
5080
Phases
at node 735 off-peak hours
Penetration ()
1
2
3
4
5
6
7
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Phase APhase BPhase C
Current total harmonic distortion (THDi)
Figure 12 THD119894 at node 775 with different PHEV penetrations
at node 740 on-peak hoursTotal harmonic distortion (THD)
Phase APhase B
Phase C30
5080
PhasesPenetration ()
Phase APhase BPhase C
0
5
10
15
20
25
30
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Figure 13 THD119894 at node 740 with different PHEV penetrations
and voltage profile have been investigated by increasingthe PHEV penetration in the distribution system It hasbeen observed that during off-peak time 50 of PHEVpenetration into the system is considered acceptable withno harmonic limits violated whereas during on-peak timeperiod the acceptable PHEV penetration is 30
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
Acknowledgments
The authors greatly acknowledge Universiti KebangsaanMalaysia for funding this project under Project no GUP-2014-072
References
[1] C-T Li C Ahn H Peng and J Sun ldquoIntegration of plug-in electric vehicle charging and wind energy scheduling onelectricity gridrdquo in Proceedings of the IEEE PES Innovative SmartGrid Technologies (ISGT rsquo12) pp 1ndash7 IEEE Washington DCUSA January 2012
[2] X Wang H He F Sun X Sun and H Tang ldquoComparativestudy on different energy management strategies for plug-inhybrid electric vehiclesrdquo Energies vol 6 no 11 pp 5656ndash56752013
[3] J Tan and L Wang ldquoAssessing the impact of PHEVs on loadfrequency control with high penetration of wind powerrdquo inProceedings of the IEEE PES TampD Conference and Expositionno 1 pp 1ndash5 Chicago Ill USA April 2014
[4] M Kazerooni New Load Demand for Electric Vehicles and ItsHarmonic Impacts on Power System Distribution TransformersUniversity of Windsor 2012
[5] R Singh B C Pal and R A Jabr ldquoDistribution systemstate estimation through Gaussian mixture model of the loadas pseudo-measurementrdquo IET Generation Transmission andDistribution vol 4 no 1 pp 50ndash59 2010
[6] TNB ldquoShared valuesrdquo in Electricity Supply Application Hand-book Tenaga National Berhad 2014
[7] S Paudyal C A Canizares and K Bhattacharya ldquoOptimaloperation of distribution feeders in smart gridsrdquo IEEE Trans-actions on Industrial Electronics vol 58 no 10 pp 4495ndash45032011
[8] M A S Masoum P S Moses and S Deilami ldquoLoad man-agement in smart grids considering harmonic distortion andtransformer deratingrdquo in Proceedings of the Innovative SmartGrid Technologies (ISGT rsquo10) pp 1ndash7 Gaithersburg Md USAJanuary 2010
[9] A Ul-Haq and C Cecati ldquoImpact of electric vehicles on voltageprofile and harmonics in a distribution networkrdquo in Proceedingsof the 1stWorkshop on Smart Grid and Renewable Energy (SGRErsquo15) pp 1ndash6 Doha Qatar March 2015
[10] S Srinivasaraghavan and A Khaligh ldquoTime managementrdquoIEEE Power and Energy Magazine vol 9 no 4 pp 46ndash53 2011
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
Modelling and Simulation in Engineering 5
pu voltage L-N voltage profile
20 40 60 8000Distance (km)
0900
0950
1000
1050
Figure 4 Voltage profile with 30 penetration
pu voltage L-N voltage profile
20 40 60 8000Distance (km)
0900
0950
1000
1050
Figure 5 Voltage profile with 80 penetration
injection of these vehicles would affect the performance of thedistribution system voltage and would definitely introduce anew peak load in the system
52 System Loss At different penetration levels the testeddistribution percentage losses are analyzed The total powerlosses collected from the line and transformer losses ofthe test system are considered as circuit losses as shownin Figure 6 The circuit power losses in percentages arecalculated over 24 hours with no PHEVpenetration as shownin Figure 7 From the figure it is noted that the circuitpower loss percentage ranges from 48 to 89 The PHEVpenetration is gradually increased with 30 integration ofPHEV in the systemand the circuit losses percentage iswithin55 to 10 as shown in Figure 8 By further increasing thePHEV penetration to 80 the power losses increase in therange of 78 to 118 as shown in Figure 9 Thus the totalcircuit power loss is directly affected by the increase of PHEVpenetration into the distribution system
Real line losses (kWkm)
15
20
25
30
35
40
45
50
55
60
Posit
ion
valu
es (y
-axi
s)
minus80minus90 minus70 minus60minus110minus120 minus100minus130
Position values (x-axis)
2
4
6
8
10
12
SubstationLoadsService transformer
MV transformerLTCVREG
Figure 6 Circuit real power losses
Percent losses for circuit with no PHEV harmonics
Circuit lossCircuit losses (bar)
2 74 91 5 83 6 11 161514 18 241712 19 20 21 22 231310
Time (hour)
0
1
2
3
4
5
6
7
8
9
Circ
uit l
oss p
erce
ntag
e (
)
Figure 7 Total circuit power loss without PHEV penetration
Figure 10 shows a comparison of the four levels of PHEVpenetration ranging from 0 to 80The figure clearly indi-cates that the system losses increase due to PHEV harmonicswith percentage increment of losses within 9 to 102 Thelosses in the system are due to the effect of current and voltageharmonic distortions
53 Total Harmonic Distortion In this case the impact ofTHD is investigated by considering 30 harmonic injection
6 Modelling and Simulation in Engineering
Percent losses for circuit
Circuit lossCircuit losses (bar)
0
1
2
3
4
5
6
7
8
9
10
Circ
uit l
oss p
erce
ntag
e (
)
213 205 6 198 1710 1312 22 2315 1611 189742 14 241
Time (hour)
Figure 8 Total circuit power loss with 30 PHEV penetration
Percent losses for circuit with 80 PHEV harmonics
2 74 91 5 83 6 11 161514 18 241712 19 20 21 22 231310
Time (hour)
0
2
4
6
8
10
12
Circ
uit l
oss p
erce
ntag
e (
)
Circuit lossCircuit losses (bar)
Figure 9 Total circuit power loss with 80 PHEV penetration
at different nodes in the test systemThe simulation was doneconsidering 24-hour load profile with 15-minute time intervalso as to capture the harmonic effects Figure 11 shows theharmonics gradually increase with respect to the increase offrequency when it is assigned to the load in the system withmaximum harmonic distortion of 178 at 850 frequencyFigures 12 and 13 show THD119894 at two different nodes 775and 740 respectively when the PHEV are connected atoff-peak hours and on-peak hours Three different PHEVpenetrations have been considered 30 50 and 80 FromFigure 12 the maximumTHD119894 value is at phase C and at 80
Penetration levels of PHEV harmonics
Without penetration30 penetration
50 penetration80 penetration
5
6
7
8
9
10
11
12
Circ
uit l
oss p
erce
ntag
e (
)
213 205 6 198 1710 1312 22 2315 1611 189742 14 241
Time (hour)
Figure 10 Percentage circuit power losses at different PHEVpenetration levels
Monitor bus 740
100 200 300 400 500 600 700 800 9000Frequency
0
2
4
6
8
10
12
14
16
18H
arm
onic
s
Figure 11 Harmonics versus frequency
PHEV penetration level Considering the harmonic limitsspecified in the IEEE Harmonic Standard the effect of THD119894during off-peak time is acceptable when the level of PHEVpenetration is 50 However above 50 penetration levelthe THD119894 values exceed the IEEE harmonic limit Figure 13shows significant increase of THD119894 reaching 15 and 25when the PHEV penetrations are 50 and 80 respectivelyThe result shows that the maximum PHEV penetration tobe adopted is 30 in which above that value unacceptableharmonic distortions will be injected into the system
6 Conclusion
The PHEV model required for harmonic power flow studieshas been developed considering a practical residential loadshape with on-peak and off-peak periods Using the PHEVmodel the impact of PHEV on currentvoltage harmonicshas been studied considering varying levels of penetrationOther power quality issues such as total circuit power losses
Modelling and Simulation in Engineering 7
Phase APhase B
Phase C30
5080
Phases
at node 735 off-peak hours
Penetration ()
1
2
3
4
5
6
7
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Phase APhase BPhase C
Current total harmonic distortion (THDi)
Figure 12 THD119894 at node 775 with different PHEV penetrations
at node 740 on-peak hoursTotal harmonic distortion (THD)
Phase APhase B
Phase C30
5080
PhasesPenetration ()
Phase APhase BPhase C
0
5
10
15
20
25
30
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Figure 13 THD119894 at node 740 with different PHEV penetrations
and voltage profile have been investigated by increasingthe PHEV penetration in the distribution system It hasbeen observed that during off-peak time 50 of PHEVpenetration into the system is considered acceptable withno harmonic limits violated whereas during on-peak timeperiod the acceptable PHEV penetration is 30
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
Acknowledgments
The authors greatly acknowledge Universiti KebangsaanMalaysia for funding this project under Project no GUP-2014-072
References
[1] C-T Li C Ahn H Peng and J Sun ldquoIntegration of plug-in electric vehicle charging and wind energy scheduling onelectricity gridrdquo in Proceedings of the IEEE PES Innovative SmartGrid Technologies (ISGT rsquo12) pp 1ndash7 IEEE Washington DCUSA January 2012
[2] X Wang H He F Sun X Sun and H Tang ldquoComparativestudy on different energy management strategies for plug-inhybrid electric vehiclesrdquo Energies vol 6 no 11 pp 5656ndash56752013
[3] J Tan and L Wang ldquoAssessing the impact of PHEVs on loadfrequency control with high penetration of wind powerrdquo inProceedings of the IEEE PES TampD Conference and Expositionno 1 pp 1ndash5 Chicago Ill USA April 2014
[4] M Kazerooni New Load Demand for Electric Vehicles and ItsHarmonic Impacts on Power System Distribution TransformersUniversity of Windsor 2012
[5] R Singh B C Pal and R A Jabr ldquoDistribution systemstate estimation through Gaussian mixture model of the loadas pseudo-measurementrdquo IET Generation Transmission andDistribution vol 4 no 1 pp 50ndash59 2010
[6] TNB ldquoShared valuesrdquo in Electricity Supply Application Hand-book Tenaga National Berhad 2014
[7] S Paudyal C A Canizares and K Bhattacharya ldquoOptimaloperation of distribution feeders in smart gridsrdquo IEEE Trans-actions on Industrial Electronics vol 58 no 10 pp 4495ndash45032011
[8] M A S Masoum P S Moses and S Deilami ldquoLoad man-agement in smart grids considering harmonic distortion andtransformer deratingrdquo in Proceedings of the Innovative SmartGrid Technologies (ISGT rsquo10) pp 1ndash7 Gaithersburg Md USAJanuary 2010
[9] A Ul-Haq and C Cecati ldquoImpact of electric vehicles on voltageprofile and harmonics in a distribution networkrdquo in Proceedingsof the 1stWorkshop on Smart Grid and Renewable Energy (SGRErsquo15) pp 1ndash6 Doha Qatar March 2015
[10] S Srinivasaraghavan and A Khaligh ldquoTime managementrdquoIEEE Power and Energy Magazine vol 9 no 4 pp 46ndash53 2011
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
6 Modelling and Simulation in Engineering
Percent losses for circuit
Circuit lossCircuit losses (bar)
0
1
2
3
4
5
6
7
8
9
10
Circ
uit l
oss p
erce
ntag
e (
)
213 205 6 198 1710 1312 22 2315 1611 189742 14 241
Time (hour)
Figure 8 Total circuit power loss with 30 PHEV penetration
Percent losses for circuit with 80 PHEV harmonics
2 74 91 5 83 6 11 161514 18 241712 19 20 21 22 231310
Time (hour)
0
2
4
6
8
10
12
Circ
uit l
oss p
erce
ntag
e (
)
Circuit lossCircuit losses (bar)
Figure 9 Total circuit power loss with 80 PHEV penetration
at different nodes in the test systemThe simulation was doneconsidering 24-hour load profile with 15-minute time intervalso as to capture the harmonic effects Figure 11 shows theharmonics gradually increase with respect to the increase offrequency when it is assigned to the load in the system withmaximum harmonic distortion of 178 at 850 frequencyFigures 12 and 13 show THD119894 at two different nodes 775and 740 respectively when the PHEV are connected atoff-peak hours and on-peak hours Three different PHEVpenetrations have been considered 30 50 and 80 FromFigure 12 the maximumTHD119894 value is at phase C and at 80
Penetration levels of PHEV harmonics
Without penetration30 penetration
50 penetration80 penetration
5
6
7
8
9
10
11
12
Circ
uit l
oss p
erce
ntag
e (
)
213 205 6 198 1710 1312 22 2315 1611 189742 14 241
Time (hour)
Figure 10 Percentage circuit power losses at different PHEVpenetration levels
Monitor bus 740
100 200 300 400 500 600 700 800 9000Frequency
0
2
4
6
8
10
12
14
16
18H
arm
onic
s
Figure 11 Harmonics versus frequency
PHEV penetration level Considering the harmonic limitsspecified in the IEEE Harmonic Standard the effect of THD119894during off-peak time is acceptable when the level of PHEVpenetration is 50 However above 50 penetration levelthe THD119894 values exceed the IEEE harmonic limit Figure 13shows significant increase of THD119894 reaching 15 and 25when the PHEV penetrations are 50 and 80 respectivelyThe result shows that the maximum PHEV penetration tobe adopted is 30 in which above that value unacceptableharmonic distortions will be injected into the system
6 Conclusion
The PHEV model required for harmonic power flow studieshas been developed considering a practical residential loadshape with on-peak and off-peak periods Using the PHEVmodel the impact of PHEV on currentvoltage harmonicshas been studied considering varying levels of penetrationOther power quality issues such as total circuit power losses
Modelling and Simulation in Engineering 7
Phase APhase B
Phase C30
5080
Phases
at node 735 off-peak hours
Penetration ()
1
2
3
4
5
6
7
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Phase APhase BPhase C
Current total harmonic distortion (THDi)
Figure 12 THD119894 at node 775 with different PHEV penetrations
at node 740 on-peak hoursTotal harmonic distortion (THD)
Phase APhase B
Phase C30
5080
PhasesPenetration ()
Phase APhase BPhase C
0
5
10
15
20
25
30
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Figure 13 THD119894 at node 740 with different PHEV penetrations
and voltage profile have been investigated by increasingthe PHEV penetration in the distribution system It hasbeen observed that during off-peak time 50 of PHEVpenetration into the system is considered acceptable withno harmonic limits violated whereas during on-peak timeperiod the acceptable PHEV penetration is 30
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
Acknowledgments
The authors greatly acknowledge Universiti KebangsaanMalaysia for funding this project under Project no GUP-2014-072
References
[1] C-T Li C Ahn H Peng and J Sun ldquoIntegration of plug-in electric vehicle charging and wind energy scheduling onelectricity gridrdquo in Proceedings of the IEEE PES Innovative SmartGrid Technologies (ISGT rsquo12) pp 1ndash7 IEEE Washington DCUSA January 2012
[2] X Wang H He F Sun X Sun and H Tang ldquoComparativestudy on different energy management strategies for plug-inhybrid electric vehiclesrdquo Energies vol 6 no 11 pp 5656ndash56752013
[3] J Tan and L Wang ldquoAssessing the impact of PHEVs on loadfrequency control with high penetration of wind powerrdquo inProceedings of the IEEE PES TampD Conference and Expositionno 1 pp 1ndash5 Chicago Ill USA April 2014
[4] M Kazerooni New Load Demand for Electric Vehicles and ItsHarmonic Impacts on Power System Distribution TransformersUniversity of Windsor 2012
[5] R Singh B C Pal and R A Jabr ldquoDistribution systemstate estimation through Gaussian mixture model of the loadas pseudo-measurementrdquo IET Generation Transmission andDistribution vol 4 no 1 pp 50ndash59 2010
[6] TNB ldquoShared valuesrdquo in Electricity Supply Application Hand-book Tenaga National Berhad 2014
[7] S Paudyal C A Canizares and K Bhattacharya ldquoOptimaloperation of distribution feeders in smart gridsrdquo IEEE Trans-actions on Industrial Electronics vol 58 no 10 pp 4495ndash45032011
[8] M A S Masoum P S Moses and S Deilami ldquoLoad man-agement in smart grids considering harmonic distortion andtransformer deratingrdquo in Proceedings of the Innovative SmartGrid Technologies (ISGT rsquo10) pp 1ndash7 Gaithersburg Md USAJanuary 2010
[9] A Ul-Haq and C Cecati ldquoImpact of electric vehicles on voltageprofile and harmonics in a distribution networkrdquo in Proceedingsof the 1stWorkshop on Smart Grid and Renewable Energy (SGRErsquo15) pp 1ndash6 Doha Qatar March 2015
[10] S Srinivasaraghavan and A Khaligh ldquoTime managementrdquoIEEE Power and Energy Magazine vol 9 no 4 pp 46ndash53 2011
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
Modelling and Simulation in Engineering 7
Phase APhase B
Phase C30
5080
Phases
at node 735 off-peak hours
Penetration ()
1
2
3
4
5
6
7
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Phase APhase BPhase C
Current total harmonic distortion (THDi)
Figure 12 THD119894 at node 775 with different PHEV penetrations
at node 740 on-peak hoursTotal harmonic distortion (THD)
Phase APhase B
Phase C30
5080
PhasesPenetration ()
Phase APhase BPhase C
0
5
10
15
20
25
30
Tota
l har
mon
ic d
istor
tion
(TH
D) (
)
Figure 13 THD119894 at node 740 with different PHEV penetrations
and voltage profile have been investigated by increasingthe PHEV penetration in the distribution system It hasbeen observed that during off-peak time 50 of PHEVpenetration into the system is considered acceptable withno harmonic limits violated whereas during on-peak timeperiod the acceptable PHEV penetration is 30
Competing Interests
The authors declare that there are no competing interestsregarding the publication of this paper
Acknowledgments
The authors greatly acknowledge Universiti KebangsaanMalaysia for funding this project under Project no GUP-2014-072
References
[1] C-T Li C Ahn H Peng and J Sun ldquoIntegration of plug-in electric vehicle charging and wind energy scheduling onelectricity gridrdquo in Proceedings of the IEEE PES Innovative SmartGrid Technologies (ISGT rsquo12) pp 1ndash7 IEEE Washington DCUSA January 2012
[2] X Wang H He F Sun X Sun and H Tang ldquoComparativestudy on different energy management strategies for plug-inhybrid electric vehiclesrdquo Energies vol 6 no 11 pp 5656ndash56752013
[3] J Tan and L Wang ldquoAssessing the impact of PHEVs on loadfrequency control with high penetration of wind powerrdquo inProceedings of the IEEE PES TampD Conference and Expositionno 1 pp 1ndash5 Chicago Ill USA April 2014
[4] M Kazerooni New Load Demand for Electric Vehicles and ItsHarmonic Impacts on Power System Distribution TransformersUniversity of Windsor 2012
[5] R Singh B C Pal and R A Jabr ldquoDistribution systemstate estimation through Gaussian mixture model of the loadas pseudo-measurementrdquo IET Generation Transmission andDistribution vol 4 no 1 pp 50ndash59 2010
[6] TNB ldquoShared valuesrdquo in Electricity Supply Application Hand-book Tenaga National Berhad 2014
[7] S Paudyal C A Canizares and K Bhattacharya ldquoOptimaloperation of distribution feeders in smart gridsrdquo IEEE Trans-actions on Industrial Electronics vol 58 no 10 pp 4495ndash45032011
[8] M A S Masoum P S Moses and S Deilami ldquoLoad man-agement in smart grids considering harmonic distortion andtransformer deratingrdquo in Proceedings of the Innovative SmartGrid Technologies (ISGT rsquo10) pp 1ndash7 Gaithersburg Md USAJanuary 2010
[9] A Ul-Haq and C Cecati ldquoImpact of electric vehicles on voltageprofile and harmonics in a distribution networkrdquo in Proceedingsof the 1stWorkshop on Smart Grid and Renewable Energy (SGRErsquo15) pp 1ndash6 Doha Qatar March 2015
[10] S Srinivasaraghavan and A Khaligh ldquoTime managementrdquoIEEE Power and Energy Magazine vol 9 no 4 pp 46ndash53 2011
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of