Airo International Research Journal March, 2016 Volume VII, … · Equations related to DVR The...

Airo International Research Journal March, 2016 Volume VII, ISSN: 2320-3714


AN ANALYTICAL STUDY OF ENHANCEMENT OF POWER QUALITY USING DVR

Mandadi Surender Reddy,

Research Scholar, Department of EE, Sunrise University, Alwar,Rajasthan

Dr. Dalvinder Kaur Mangal, Supervisor, Department of EE, Sunrise University, Alwar,Rajasthan

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ABSTRACT

The Power Quality Analysis tries to bring out electricity customers for upgraded power quality

with utilization of power gadgets. The investigation work incorporates through and through

analysis of the collaboration among loads, power systems and diverse power quality change

gadgets. It in the end prompts better framework of alleviation gadgets like Dynamic Voltage

Restorer (DVR), Distribution Static Synchronous Compensator (DSTATCOM) and Unified

Power Quality Conditioner (UPQC) to help diverse power quality related issues. The standard

objective of this suggestion is to develop a model of DVR, DSTATCOM and UPQC for

development of power quality. DVR is one of the custom power gadgets that are used as a

reasonable response for the insurance of delicate burdens against voltage agitating impacts in

power circulation system. The capability of the DVR depends upon the execution of the control

technique, which related with trading the inverters. While modifying, the transient response of

the DSTATCOM is basic for non linearly contrasting and uneven burdens. The DC Link voltage

is extended over the reference esteem when the stack is out of the blue removed and it is reduced

underneath its reference esteem exactly when the load is out of the blue extended. Customarily, a

Proportional Vital (PI) controller is used to keep up the DC Link voltage at the reference esteem.

INTRODUCTION

At present, modern industrial devices are

normally in view of power electronic

devices, for example, programmable logic

controllers and customizable speed drives.

The electronic devices are exceptionally

receptive to unsettling influences and turn

out to be less tolerant to power quality

issues, for example, voltage sags, swells and

harmonics. Voltage plunges are thought to

be a standout amongst the most serious


unsettling influences to the industrial

equipments.

DVRs are a class of custom power devices

for giving steady dissemination power

quality. They utilize a progression of voltage

support innovation utilizing strong state

switches for remunerating voltage

sags/swells. The DVR applications are for

the most part for touchy burdens that might

be impressively influenced by fluctuations

in system voltage.

LITERATURE REVIEW

DVR system in perspective of downstream

accuse compelling limit and a transition

charge indicate criticism controller has been

proposed and fused by Yun Wei Li et al.

Detail of the healthiness and mix up

following execution considered for authentic

assurance of weighting capacities. Critical

increases at positive and negative line

frequencies affected with the tuning of

coordinated H∞ controller. Thus the positive

and negative grouping segments would

enough immediate. H∞ voltage circle and

internal current circle is arranged and

embedded by Yun Wei Li et al.

For the compensation of power quality

issues viz. voltage hangs, voltage harmonics

and voltage unpredictable qualities a two

level DVR with dull controller was

displayed by Pedro Roncero-Sanchez et al.

To reduce the voltage hangs and control the

DC Link voltage, a course of action

compensating device which is transformer

less self charging DVR was depicted by Eng

Kian Kenneth SNG Et Al. They found that

the cost and size of the device can be

reduced due to the transformer

nonattendance. The DC Link voltage

heading instrument smoothens in light of

channel inductor vitality.

Constant state analysis based DVR was

appeared by Arindam Ghosh and Gerard

Ledwich . Time fluctuating reference

voltages of a DVR can be overcome

different decisions. VSI is used to

comprehend the structure of the DVR.

A DVR is proposed in light of power

mastermind analysis, a joined feed forward

and state input control structures for the

compensation of voltages. Basic framework

rules viz. control delay and channel cutoff

repeat are similarly proposed for the

controller of a DVR system was proposed

by Hyosung Kim Seung-Ki Sul.


BASIC CONFIGURATION OF DVR

The basic setup of the DVR comprises of the

accompanying fundamental units.

1 An Injection/ Booster

transformer

2 A Harmonic filter

3 Storage Devices

4 A Voltage Source Converter

5 DC charging circuit

6 A Control and Protection

system

Injection/ Booster Transformer

The Injection/Booster transformer is an

especially composed transformer that

endeavors to confine the coupling of noise

and transient energy from the essential side

to the secondary side. Its significant errands

are given beneath.

Figure 1 Schematic Diagram of DVR

Voltage Source Converter

A VSC is a power electronic system

comprises of a storage device and

exchanging hardware, which can deliver a

sinusoidal voltage at any important

frequency, magnitude and phase angle. In

the DVR application, the VSC is utilized to

quickly supplant the supply voltage or to

create the piece of the supply voltage which

is absent.

DC Charging Circuit

The dc charging circuit has two main tasks.


1 The first task is to charge the

energy source after a sag

compensation event.

2 The second task is to

maintain DC Link voltage at

the nominal DC Link voltage.

Equations related to DVR

The load impedance Zth relies upon the

blame level of the load transport. At the

point when the system voltage (Vth) drops,

the DVR infuses a seriesvoltage VDVR

through the injection transformer with the

goal that the coveted load voltage magnitude

VL can be kept up. The arrangement infused

voltage of the DVR can be composed as

(1)

Where

VL: The desired load voltage magnitude

ZTH: The load impedance.

IL: The load current

VTH: The system voltage during

fault condition The load current

IL is given by,

(2)

When VL is considered as a reference

equation can be rewritten as,

(3)

Are angles of VDVR, ZTH ,VTH

respectively and is Load power angle The

complex power injection of the DVR can be

written as,

(4)

It requires the injection of just reactive

power and the DVR itself is fit for

producing the reactive power.

SIMULATION OF DVR WITH PI

CONTROLLER AND FUZZY LOGIC

CONTROLLER

Computer simulation has turned into a key

piece of the power electronics design

process. DVR is a power electronics device

which comprises of voltage source converter

as a critical element. The general design

process can be abbreviated using computer

simulations, since it is typically less

demanding to examine the impact of a

parameter on the system conduct in


simulation. Primary system simulation

model without DVR has been made in

Matlab/Simulink:

Figure 2 Main Systems without DVR

To check the working of a DVR utilized to

evade voltage sags amid hamper, a

resistance of 0.4 Ω. Such fault is connected

for 400msec. The limit of the dc storage

device is 5 kV.

Figure 3 PI Controller subsystems

The test system of without DVR amid faults

like three phase fault, single line to ground

fault and twofold line fault is investigated.

Watched load voltage issues like sag, swell


and interruption. At that point to beat these

issues DVR is associated for the test system

notwithstanding the controllers like PI

Controller with parameters KP = 0.5, Ki =

50 and test time 50µsec and Fuzzy Logic

Controller for the upgrade of the execution

and THD change.

Figure 4 Main diagram of DVR with Fuzzy Logic Controller

Simulation Results for Voltage Sag

during Three Phase Fault

The principal test system contains no DVR

and a three-phase circuit fault is connected,

by means of a fault resistance of 0.4ω, amid

the period 500 to 900ms. The load voltage is

35% as for the reference voltage. Fig. 4.14

demonstrates the RMS load voltage sag at

the RL load (R = 10ω and L = 10-6H) for

the situation when the system works with no

DVR.

The second test system is completed

utilizing an indistinguishable situation from

above however now DVR with PI Controller

and DVR with Fuzzy Logic Controller are in

operation. The aggregate simulation time

frame is 1400 ms. At the point when the

DVR is in operation the voltage sag is

moderated totally and the rms voltage of the

delicate load is kept up at 98% while DVR

with FLC as appeared in Fig. 4.15 with the

limit of the dc storage device is 5 kV.


Figure 5 Voltage VRMS at the load without DVR

The PWM control conspires controls the

magnitude and the phase of the infused

voltages, reestablishing the RMS voltage

viably. The sag moderation is performed

with a smooth, steady and fast DVR

reaction. Two transient undershoots are

watched when the DVR comes all through

operation. It ought to be noticed that in the

DVR, the dc voltage is provided by a dc

capacitor. A few simulations were

completed to evaluate the execution of the

DVR as a component of short out closeness

and the remuneration ability of DVR relies

upon the limit of the energy storage device.

Fig. 4.16 and Fig. 4.17 demonstrate that the

repaying ability of DVR relies upon the

limit of the DC energy storage.

Simulation Results for Voltage Sag

during Single Line to Ground Fault

The principal test system contains no DVR

and a solitary line to ground fault is

connected and the comparing waveform as

appeared in Fig. 4.18, through a fault

resistance of 0.2 Ω, amid the period 500 to

900 ms. the voltage sag at the load voltage is

30% concerning the reference voltage. The

second test system is done utilizing an

indistinguishable situation from above

however now DVR with PI Controller and

DVR with Fuzzy Logic Controller are in


frame is 1400 ms.



Simulation Result of Voltage Sag during

Double Line Fault

The primary test system contains no DVR

and a twofold line fault is connected through

a fault resistance of 0.1 Ω, amid the period

500 to 900 ms. the voltage sag at the load

voltage is 65% concerning the reference

voltage. Fig. 4.23 demonstrates the RMS

voltage at the load point for the situation

when the system works with no DVR. The


indistinguishable situation from above yet

now DVR with PI Controller and DVR with

Fuzzy Logic Controller are in operation. The

aggregate simulation time frame is 1400

ms.\



Simulation Result of Voltage Interruption

during Three- Phase Fault

The primary test system contains no DVR

and three phase fault is connected by means

of a fault resistance of 0.001 Ω, amid the

period 500 to 900 ms. The voltage at the

delicate load is 0% concerning the reference

voltage. Fig. 4.28 demonstrates the RMS

voltage at the load point for the situation

when the system works with no DVR.The


indistinguishable situation from above

however now DVR with PI Controller and

DVR with Fuzzy Logic Controller are in


frame is 1400 ms.\


CONCLUSION

DVR is an as of late proposed arrangement

associated solid state device that infuses

voltage into the system with a specific end

goal to manage the heap side voltage. It is

typically introduced in a dissemination

system between the supply and the basic

load feeder at the purpose of regular

coupling. Other than voltage sags and swells

compensation, DVR can likewise included

different components, those are line voltage

harmonics compensation, diminishment of

transients in voltage and fault current

impediments and afterward investigate the

dynamic and unfaltering state execution of


DVR. The consequences of voltage and

current waveforms of DVR utilizing PI

Controller and Fuzzy Logic Controller with

voltage list amid three stage fault, voltage

list amid single line to ground fault, voltage

hang amid twofold line fault, voltage

interruption amid three stage fault and

voltage swell focuses are broke down. DVR

with Fuzzy Logic Controller performs better

among DVR with PI Controller and Fuzzy

Logic Controller.

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