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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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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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Cont
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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Cont
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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