Var Compensator

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Advisor Mr.Balakrishinan 1

Design &Implementation Of Low Voltage Dynamic VARCompensator

B.SC THESIS DEFENSE PRESENTATION

By

1.NETSANET TADIWOS RET786238723

2. WOLDEMARIAMWORKU

3.YESUNEH CHALLA

4.ZEKERIEYA HASSEN


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Presentation outline

1. Introduction2. Problem statement3. Objective4. Methodology5. Scope of the project

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Cont

6. Expected out come7. Review of literatures'8. Design & analysis9. Microcontroller algorithm scheme10. Result & discussion11. Conclusion & Recommendation

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.

Active and Reactive powerEffect of Inductive loadsMajor industrial loads are MOTORS InductiveLoss is Measured in terms of POWERFACTOR

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1 Introduction


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What is Power Factor

The ideal power factor is unity, or one.When the power factor is less than one themissing power known as reactive power

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Power Factor CORRECTION

A poor power factor can be improved by theaddition of REACTIVE POWER of opposite phaseCapacitors REACTIVE POWER is opposite to

Reactive Power in Inductive loadCapacitors can correct POWER LOSSAND improve POWER FACTOR to UNITY

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2. problem of statement

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.This project is developed to improve the weakness ofstatic capacitor bank.Static capacitor bank is a traditional method was usedto improve the power factor by using capacitor bank.The weakness of the static capacitor bank, which affect

the operations:Capacitive compensation does not change according toincrease or reduction in loads.Could not detect load rating that change inefficiency

Operation and power factor correction not optimized


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3

Main objective

Maintain PF near UNITYBy Switching ON and OFF of capacitorsActivated by RELAYS

Automatically by Microcontroller basedCONTROL UNIT

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.Objective


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Cont

Specific objective

Apply consistent Measuring & Verificationmethodologyquantify and identify the power factor of

the power system.Identify the lead and lag conditions

Demonstrate the operation of a Dynamic

VAR compensator with the help of test loadssuch as Choke, High impedance motor etc.

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Software partPROGRAMING PIC16f84A. Proteus For Simulation Of SoftwareMicrochips MPLAb X IDE & XC8 C compilerHardware part

The circuitry design involvesMicrocontroller current transformer

RelaysCapacitors

Inductor voltage transformer etc.comparator

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4. Methodology


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5 Scope of the project

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power and Control circuit of unloader motorOperation single-phase capacitor bank(220V, 50Hz).

developed around the microcontroller (PIC16F84A) by using XC8 compiler under MPLABX IDE.

developed by using current transformer,which senses the current according to load

change in single-phase inductive loads


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6 Expected out comeThe power factor with inductive loads will bemeasured and highlighted as the fundamentalproblem to be solved by dynamicallyconnecting and disconnecting capacitors.The design will be tested and demonstratedwith resistive and inductive test loads.The improvement in the power factor as a

result of the dynamic switching of thecapacitors will be proved.

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7 Literature review

Capacitor banks

A bank of capacitors is connectedacross the load.

Since the capacitor takes leadingreactive power,overall reactive power taken from

the source decreases,consequently system power

factor improves14


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Cont

Advantages1. They have low losses.2. They require little or no maintenance as there isno rotating parts.

3. They can be easily installed, as they are lightand do not require foundation.4.They can work under ordinary atmosphericcondition.

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Disadvantages of using capacitor banks1. They have short life span of 8-10 years.2. They are easily damaged if exceed the ratedvalue.

3. Once damaged, they have to be removed, astheir repairing is uneconomical

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Cont

Static thyristor controlStatic thyristor controlled reactors areconnected in parallel with load for the control ofreactive power flow. With increase in the size of

industrial connected loads, fast reactive powercompensation has become necessary. For suchloads, thyristor controlled reactors are nowbecoming increasingly popularThyristor controlled reactors provide partialcancellation of Harmonics.

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Cont

Thyristor switched capacitorA thyristor switched capacitor (TSC) is a type ofequipment used for compensating reactive power inelectrical power systems. It consists of a power

capacitor connected in series with a bidirectionalthyristor valve and, usually, a current limitinginductor (reactor).A TSC is usually a three-phase assembly, connectedin either a delta or a star arrangement. Unlike theTCR, a TSC generates no harmonics and so requiresno filtering

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Cont

static VAR compensatorDue to the magnetizing current of inductionmotors, it is easy to correct each individual motorby connecting the correction capacitors to the

motor starters. With static correction, it isimportant that the capacitive current is less thanthe inductive demagnetizing current of theinduction motor.When the motor is Off Line, the capacitors arealso Off Line


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Cont

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Advantages

The main advantage of SVCs over simple mechanicallyswitched compensation schemes is their near-instantaneousresponse to changes in the system voltage. For this reason,

they are often operated at close to their zero-point in orderto maximize the reactive power correction they can rapidlyprovide when required.They are in general cheaper, higher capacity, faster, andmore reliable than dynamic compensation schemes such as

synchronous condensers


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Cont

Centralized compensationThe reactive power is subdivided in a number ofcapacitor steps that can be connectedindependently.

The advantage of this system is that the totalcapacitor power is smaller than the sum needed forindividual compensation. Therefore, this system isa good economical solution

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Group compensation

Several inductive loads can be grouped together andequipped with a common capacitor bank.This system usually applies for users that have their owninstallations with distribution transformers and high

voltage power lines/cablesIndividual compensation

This type of compensation is applied to motors, transformers, and in

general to loads with a high time of operation.

Capacitors are directly connected in parallel to the terminals of the

loads.

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8 Design and analysis

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The block diagram contains the following sectionsPower supply section Microcontroller sectionMeasurements comparator section


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Cont

.

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TR1

TRAN-1P2S

TR2

TRAN-1P2S

D31N751A

D41N751A

D51N751A

D61N751A

D7

1N751A

D8

1N751A

R1

1.0K

R2

1.0K

R3

1.0K

R4

1.0K

R510R

V1VSINE

GND

D1

UF4003

RL1

12V

RL2

12V

RL3

12V

RL4

12V

Q1BC548C

Q2BC548C

Q3BC548C

Q4BC548C

L1

MPZ2012S300AL2

MPZ2012S300AL3

MPZ2012S300A

L4

MPZ2012S300A

SW1

SW-SPST

SW2

SW-SPST

SW3

SW-SPST

SW4

SW-SPST

C11000u

C21000u

C31000u C4

1000u

3

2

6

7

4 8

1

U2

LM308A

3

2

6

7

4 8

1

U3

LM308A

OSC1/CLKIN16

RB0/INT 6

RB1 7

RB2 8

RB3 9

RB4 10

RB5 11

RB6 12

RB7 13

RA0 17

RA1 18

RA2 1

RA3 2

RA4/T0CKI

3

OSC2/CLKOUT15

MCLR4

U1

PIC16F84A

X1CRYSTAL

D2

1N4003

VI1

VO 3

GND

2

7812

VI2

VO 3

GND

1

U57912

C5470u

C6470u

C7470u

C8470u

D91N4003

D101N4003 D11

1N4003

D121N4003

D13

LED

D14

LED

R6

330

R7

330

VI1

VO 3

GND

2

7805

C9470u

C10470u


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Cont

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Capacitor bank design considerationsLoad voltage,Load current andFrequency


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9 Microcontroller algorithm scheme

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First stage is concern with the step downarrangement of incoming voltage and currentsignals into the PIC level voltage (e.g. 5V).

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10 Result & Discussion


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Second stage is concerned with zero crossing level

detection by using an IC (IC # lm324) of both the comingsignals. This is done by Voltage signal can be acquired byusing the output of Potential Transformer for detection.Current signal can be acquired by using CurrentTransformer connected at main line

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Cont


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When resistive load is ON, there is no lagging incurrent and voltage signals and are in phase asshown in fig 4.3 .In this case the power factorwould be 0.9 as the referenced value, so there is

no insertion of capacitor

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Cont


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When a large inductive is ON, there is large phase

delay in between current and voltage signals.Microcontroller senses the delay produced by theload, and according to the delay, it inserts thedesired value of capacitor to improve the powerfactor of the system

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Cont


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When Small Inductive Load is ON, there is phase delay in

between current and voltage signals. Microcontroller sensesthe delay produced by the load, and according to the delay,it inserts the desired value of capacitor to improve thepower factor of the system

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Cont


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When Both Resistive and inductive Load is ON,there is large phase delay in between current andvoltage signals. Microcontroller senses the delayproduced by the load, and according to the delay,

it inserts the desired value of capacitor toimprove the power factor of the system

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Cont


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Result after a capacitor inserted for smallinduction motor

Cont


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Result For magnetic ballast before capacitor inserted

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Cont


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Result after a capacitor inserted in a magnetic ballast

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Cont


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Result after a capacitor inserted in large induction motors

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Cont


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This project work is an attempt to design andimplement low voltage dynamic VAR compensatorusing PIC Microcontroller (16F84A). PICMicrocontroller senses the power factor by

continuously monitoring the load of the system, andthen according to the lagging behavior of powerfactor due to load it performs the control actionthrough a proper algorithm by switching capacitor

bank through different relays and improves thepower factor of the load..

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11 Conclusion


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This project gives more reliable and user-friendly

power factor controlling system by continuouslymonitoring the load of the system. Measuring ofpower factor from load is achieved by using PICMicrocontroller developed algorithm to determineand trigger sufficient switching of capacitors inorder to compensate demand of excessive reactivepower locally, thus bringing power factor near to

desired level

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Cont


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Dynamic VAR compensation using capacitor banks

is very efficient as it reduces the cost bydecreasing the power drawn from the supply andas it operates automatically that means no personrequired to operate this, so this Automated Powerfactor Correction using capacitive load banks mustbe used for the industries purpose in the future.This project was designed only for single-phase

inductive loads. However, it will be better tomodified for three phase inductive loads forindustrial as well as commercial use.

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12 Recommendation


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Dynamic VAR compensator using relay as

switching device used to switch on and off therequired capacitor value. However, it has a drawback when the relay contacts. In order to avoidthis drawback, it is better to do this dynamic VARcompensator using fast power electronicsswitching devices in the future.Install conditions as harmonic filters to avoid

harmonic resonance problems and excessivevoltage distortion levels

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Cont.


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Thank you

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Var Compensator

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