8/3/2019 Control Technique for Compensation of Neutral Current Harmonics
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5/3/12 Dept of Electrical and
CONTROL TECHNIQUE FORCOMPENSATION OFNEUTRAL CURRENT
HARMONICSDone by,ANOOP K G7805
E6B
Guided by,Dr. BIJUNA KUNJUDept of Electrical and Electronics
11Dept of Electrical and
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INTRODUCTION
Linear and Non-linear loads
Unbalance Neutral current
Quality of power system
Harmonics in power system
Effect of Harmonics in power system
Control of Harmonics
Selective filtering of HarmonicsDept of Electrical and 22
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WHAT IS HARMONICS ?
Distortion of actual waveform
Due to superposition of higher frequencycomponents
Complex waveform
Analyzed using Fourier series
Causes power quality problems
Zero sequence component in the voltage
causes Dept of Electrical and 33
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How are Harmonics Formed?
44Dept of Electrical and
F(t)=
Fig1
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Supply
Voltage
NonlinearLoad
SupplyImpedance
Nonlinear Operating Conditions
SupplyCurrent
Vout
+
-
55Dept of Electrical and
Fig.2
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What Problems do Harmonics
Create ?
Excessive heating of the neutral
Degradation of cable dielectric and jacket
Core loss and copper loss in transformer
Pulsating torque in motors and generators
Reduces the trip point of circuit breakers
Interference with telephone signals
Inception of corona
Power quality reducesDept of Electrical and 66
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Active Filter for Three phase
Four wire System
Dept of Electrical and 1010
Fig. 3. Active filtering scheme for three phase four wiredistribution system
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Neutral CurrentReduction
Dept of Electrical and 1111
Fig. 4. Zero sequence equivalent
circuit
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Controller for Active
Filter
Dept of Electrical and 1212
In
vn
Powercalculator
Ia
Ire
Va
Vre
Harmoniccurrent
calculator
comparator
Ih
Pa
Pre
Phaseangle
detector
IN
Fig.5
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Simulation
Result
Dept of Electrical and 1313
Simulation result of the proposedactive filter circuit control
Fig.6
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Simulation Result
Dept of Electrical and 1414
Spectra of phase current before applyingactive filter
Spectra of phase current after applying
active filter
Fig.7
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CONCLUSION
Dept of Electrical and 1515
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REFERENCE G.Kamath, N.Mohan Hardware implementation of a novel reduced rating active filter for three
phase four wire load IEEE conference
M. Aredes , E.H Watanabe New control algorithms for series and shunt three phase four wireactive power filters IEEE transactions
T M Gruz, A survey of neutral currents in three phase computer
power IEEE transactions
T Key and J S Lai, Analysis of harmonic mitigation methods for
building wiring system
P P Khera, Application of Zigzag transformers for reducing harmonics
in the low voltage distribution system IEEE conference proceedings
P.Tai Cheng Design of neutral harmonic mitigator for three phase four wire distribution systemIEEE meeting Dept of Electrical and 1616
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REFERENCE H.Akagi and Y.Kanazawa Instantaneous reactive power compensators
comprising witching devices without energy storage components IEEE
transactions
Rajesh Gupta and Kamala Kant Mishra, Review of CFL and its harmonicimpact on electrical distribution system, Electrical India Magazine, CharyPublication (Mumbai), Feb. 2010.
http://en.wikipedia.org/wiki/Harmonics_(electrical_power)
http://en.wikipedia.org/wiki/Power_system_harmonics
Dept of Electrical and 1717
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5/3/12 Dept of Electrical and
THANKS
Dept of Electrical and 1818