PSCAD&Simula,on&of&Grid3Tied&Photovoltaic&...
Transcript of PSCAD&Simula,on&of&Grid3Tied&Photovoltaic&...
PSCAD Simula,on of Grid-‐Tied Photovoltaic Systems and Total Harmonic Distor,on Analysis
Abdulrahman Kalbat Columbia University in the City of New York
(Teaching Assistant at UAE University “currently on leave”)
October 4th, 2013
10/04/2013 /24
Paper Structure
• PSCAD Model of Grid-‐Tied Photovoltaic System
– Detailed descripMon of all model components and the control blocks
• Total Harmonic Distor,on (THD) Analysis
– IEEE Std 929-‐ 2000 “IEEE Recommended PracMce for UMlity Interface
of Photovoltaic (PV) Systems”
– THD analysis using PSCAD
– Effects of solar irradiaMon on both current and voltage THD
Abdulrahman Kalbat Columbia University 2
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Pscad Model Of Grid-‐Tied Photovoltaic System
Abdulrahman Kalbat Columbia University 4
gt1
gt2
gt3
gt4
gt5
gt6
1
EaEc Eb
Eab
Ebc
Idc
35
2 6 4
135
2 6 4
Ia_motor
dcVltg
#1 #2
P = 0.1467Q = -0.0006585
V = 11.06
VA
2e-4
80000
TimedBreakerLogic
Closed@t0 BRK_cap
BR
K_cap
R=0
Icha
rge
5
10000
5
T1
Vpv
Icon
0.01 [H]
V+
G
Tcell
V-
SolRad
CellTemp
Ipv
Solar RadiaMon +
Cell Temperature Data
PV Array +
Output Capacitor
DC-‐DC Converter for MPP Tracking 3-‐phase Inverter Bridge
AC Filter
Transformer 230V/11kV
UMlity Grid 11kV
• Model provided by PSCAD support team
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Pscad Model Of Grid-‐Tied Photovoltaic System
Abdulrahman Kalbat Columbia University 5
gt1
gt2
gt3
gt4
gt5
gt6
1
EaEc Eb
Eab
Ebc
Idc
35
2 6 4
135
2 6 4
Ia_motor
dcVltg
#1 #2
P = 0.1467Q = -0.0006585
V = 11.06
VA
2e-4
80000
TimedBreakerLogic
Closed@t0 BRK_cap
BR
K_cap
R=0
Icha
rge
5
10000
5
T1
Vpv
Icon
0.01 [H]
V+
G
Tcell
V-
SolRad
CellTemp
Ipv
Solar RadiaMon +
Cell Temperature Data
PV Array +
Output Capacitor
DC-‐DC Converter for MPP Tracking 3-‐phase Inverter Bridge
AC Filter
Transformer 230V/11kV
UMlity Grid 11kV
minimizes the ripple of the PV source current
10/04/2013 /24
Pscad Model Of Grid-‐Tied Photovoltaic System
Abdulrahman Kalbat Columbia University 6
gt1
gt2
gt3
gt4
gt5
gt6
1
EaEc Eb
Eab
Ebc
Idc
35
2 6 4
135
2 6 4
Ia_motor
dcVltg
#1 #2
P = 0.1467Q = -0.0006585
V = 11.06
VA
2e-4
80000
TimedBreakerLogic
Closed@t0 BRK_cap
BR
K_cap
R=0
Icha
rge
5
10000
5
T1
Vpv
Icon
0.01 [H]
V+
G
Tcell
V-
SolRad
CellTemp
Ipv
Solar RadiaMon +
Cell Temperature Data
PV Array +
Output Capacitor
DC-‐DC Converter for MPP Tracking 3-‐phase Inverter Bridge
AC Filter
Transformer 230V/11kV
UMlity Grid 11kV
Opera,ng at Maximum Power Point 8><
>:
�I/�V = �I/V, at MPP
�I/�V > �I/V, left of MPP
�I/�V < �I/V, right of MPP
Incremental Conductance
Tracking Algorithm
!
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Pscad Model Of Grid-‐Tied Photovoltaic System
Abdulrahman Kalbat Columbia University 7
gt1
gt2
gt3
gt4
gt5
gt6
1
EaEc Eb
Eab
Ebc
Idc
35
2 6 4
135
2 6 4
Ia_motor
dcVltg
#1 #2
P = 0.1467Q = -0.0006585
V = 11.06
VA
2e-4
80000
TimedBreakerLogic
Closed@t0 BRK_cap
BR
K_cap
R=0
Icha
rge
5
10000
5
T1
Vpv
Icon
0.01 [H]
V+
G
Tcell
V-
SolRad
CellTemp
Ipv
Solar RadiaMon +
Cell Temperature Data
PV Array +
Output Capacitor
DC-‐DC Converter for MPP Tracking 3-‐phase Inverter Bridge
AC Filter
Transformer 230V/11kV
UMlity Grid 11kV
Crea,ng MPPT voltage reference
!
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Pscad Model Of Grid-‐Tied Photovoltaic System
Abdulrahman Kalbat Columbia University 8
gt1
gt2
gt3
gt4
gt5
gt6
1
EaEc Eb
Eab
Ebc
Idc
35
2 6 4
135
2 6 4
Ia_motor
dcVltg
#1 #2
P = 0.1467Q = -0.0006585
V = 11.06
VA
2e-4
80000
TimedBreakerLogic
Closed@t0 BRK_cap
BR
K_cap
R=0
Icha
rge
5
10000
5
T1
Vpv
Icon
0.01 [H]
V+
G
Tcell
V-
SolRad
CellTemp
Ipv
Solar RadiaMon +
Cell Temperature Data
PV Array +
Output Capacitor
DC-‐DC Converter for MPP Tracking 3-‐phase Inverter Bridge
AC Filter
Transformer 230V/11kV
UMlity Grid 11kV
!
Connect DC system to AC system
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Pscad Model Of Grid-‐Tied Photovoltaic System
Abdulrahman Kalbat Columbia University 9
gt1
gt2
gt3
gt4
gt5
gt6
1
EaEc Eb
Eab
Ebc
Idc
35
2 6 4
135
2 6 4
Ia_motor
dcVltg
#1 #2
P = 0.1467Q = -0.0006585
V = 11.06
VA
2e-4
80000
TimedBreakerLogic
Closed@t0 BRK_cap
BR
K_cap
R=0
Icha
rge
5
10000
5
T1
Vpv
Icon
0.01 [H]
V+
G
Tcell
V-
SolRad
CellTemp
Ipv
Solar RadiaMon +
Cell Temperature Data
PV Array +
Output Capacitor
DC-‐DC Converter for MPP Tracking 3-‐phase Inverter Bridge
AC Filter
Transformer 230V/11kV
UMlity Grid 11kV
Smoothing the inverter output
!
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Pscad Model Of Grid-‐Tied Photovoltaic System
Abdulrahman Kalbat Columbia University 10
gt1
gt2
gt3
gt4
gt5
gt6
1
EaEc Eb
Eab
Ebc
Idc
35
2 6 4
135
2 6 4
Ia_motor
dcVltg
#1 #2
P = 0.1467Q = -0.0006585
V = 11.06
VA
2e-4
80000
TimedBreakerLogic
Closed@t0 BRK_cap
BR
K_cap
R=0
Icha
rge
5
10000
5
T1
Vpv
Icon
0.01 [H]
V+
G
Tcell
V-
SolRad
CellTemp
Ipv
Solar RadiaMon +
Cell Temperature Data
PV Array +
Output Capacitor
DC-‐DC Converter for MPP Tracking 3-‐phase Inverter Bridge
AC Filter
Transformer 230V/11kV
UMlity Grid 11kV
• Voltage adjustment (step up or down) • Galvanic insola,on
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Total Harmonic Distor,on (THD) Analysis
• Harmonics:
– are sinusoidal components of a periodic wave having a frequency that
is at mulMples of the fundamental frequency
• Generated in PV systems by the converters that are using
switching techniques that generate signals that are not
perfect sinusoidal.
• UMlity grid is already being injected with harmonics by the
non-‐linear load
– ConnecMng PV systems will add a stress on the power quality of the
grid.
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IEEE Std 929-‐ 2000
• “IEEE Recommended PracMce for UMlity Interface of
Photovoltaic (PV) Systems”
1. Total harmonic current distorMon shall be less than 5% of the
fundamental frequency current at rated inverter output.
2. Each individual harmonic shall be limited as follows
• If odd harmonic à limits in the table
• If even harmonic à less than 25% of the odd harmonic limits listed
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Odd Harmonic Distortion Limit3rd � 9th < 4.0 %11th � 15th < 2.0 %17th � 21st < 1.5 %23rd � 33rd < 0.6 %Above the 33rd < 0.3 %
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IEEE Std 929-‐ 2000
• This standard is valid for medium and high voltage level
electric uMlity
– Simulated grid is 11 kV 60 Hz system (medium)
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Voltage Class Nominal Line-Line RMS Voltage
Low Voltage < 600 VMedium Voltage 600 V � 69 kVHigh Voltage 69 kV � 230 kVExtra High Voltage 230 kV � 1100 kVUltra High Voltage > 1100 kV
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THD Analysis using PSCAD
• CalculaMon of Total Harmonic DistorMon
1. Fast Fourier Transform (FFT) à Harmonic frequency components
magnitude (each index)
2. Using harmonic frequency components
• Total Harmonic DistorMon (%)
• Individual Harmonic DistorMon (%)
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X1
X2
X3
Ph1
Ph2
Ph3
Mag1 Mag2 Mag3
(15)
(15)
(15)
(15) (15) (15)
dc1 dc2 dc3
F F T
F = 60.0 [Hz]
12
3
I_pcc
HarmonicDistortion
Total
Individual
15
15
HarmonicDistortion
Total
Individual
15
15
HarmonicDistortion
Total
Individual
15
15
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THD Analysis using PSCAD
• IEEE Std 929-‐ 2000 – Total harmonic current distorMon shall be less than 5% of the
fundamental frequency current at rated inverter output.
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THD Analysis using PSCAD
• IEEE Std 929-‐ 2000 – Each individual harmonic shall be limited as follows
• If odd harmonic à limits in the table
• If even harmonic à less than 25% of the odd harmonic limits listed
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THD Analysis using PSCAD
• Expanding the harmonic index to 63
– The harmonics with indices from 38 to 46 are violaMng the distorMon
limits, which is 0.3%
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Solar Irradia,on Effects on Current and Voltage THD
• IEEE Std 929-‐ 2000 – Limits were established for THD of the current at PCC
• It is a common pracMce, especially in the case of grid-‐Med PVs,
to pay more ahenMon to current THD analysis.
• WHY?
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Solar Irradia,on Effects on Current and Voltage THD
• Current THD Vs. Solar IrradiaMon – Current THD decreases as the Solar IrradiaMon increases
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Solar Irradia,on Effects on Current and Voltage THD
• Voltage THD Vs. Solar IrradiaMon – Voltage THD is not affected by the varying Solar IrradiaMon
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Solar Irradia,on Effects on Current and Voltage THD
• Current THD Vs. Solar IrradiaMon – PV systems operaMng under low solar irradiaMon values inject more
current harmonics into the uMlity grid than at high irradiaMon values.
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Solar Irradia,on Effects on Current and Voltage THD
• This problem might force PV system operators to
– Disconnect the PV system from the grid to avoid paying the high THD
levels penalty specified by the uMlity operator.
– Use beher filtering techniques
• Passive filters (RLC)
• Shunt AcMve Power Filters (used for harmonic compensaMon)
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