International Journal of Engineering Trends and Technology (IJETT) – Volume 20 Number 5 – Feb 2015
Analysis on Mitigation of Current Harmonics Using Shunt Hybrid Active
Power Filter Strategy for Three Phase Three Wire Distribution System
S.Srinivasan1, G.Annalakshmi2, I.Arivazhagan3
1,2,3
Assistant Professor & Department of EEE & Alpha College of Engineering and Technology, Puducherry, India.
Abstract— This paper investigates the three phase three wire
shunt hybrid active power filter strategy for compensating the
current harmonics and power factor corrections. The extension
synchronous reference frame (ESRF) technique is modelled as dc
voltage controller for shunt hybrid active power filter strategy.
This technique utilizes PI controller for regulating dc-link
voltage. The performance of the shunt hybrid active power filter
strategy is analysed for three phase rectifier RL load. The
simulation analysis for mitigating current harmonics is carried
out in Matlab Simulink environment.
Keywords— Active filter, current harmonic mitigation, hybrid filter,
extension synchronous reference frame.
I. INTRODUCTION
The recent growth of nonlinear load such as UPS, SMPS,
refrigerators, computer, laser printers, fax machines, discharge
lamps, arc furnaces, battery chargers, have caused a greater
awareness on power quality issues in power system. These
nonlinear loads create current harmonics in the transmission
and distribution system [3]. The current harmonics present in
the system lead to distortion in power quality, i.e. lagging of
power factor, excess power is consumed by the load,
overheating of equipments, harmonic resonance present in the
utility, increased losses, interference to communication
network, malfunction of instrument, and failure of electrical
machines etc. An exhaustive of research is carried out to
identify the appropriate compensating device for mitigating
the power quality related problems [6],[8]. These power
quality problems are compensated by using suitable custom
power devices. The shunt active power filter strategy is one of
the popular custom power device to mitigate the power quality
related problems such as harmonic distortion, balancing
current, neutral current and power factor correction. The
hybrid filter is the combination of passive filter and active
filter are connected in series. These filters are connected
parallel to the transmission at the point of common coupling
(PCC). In this paper the shunt hybrid active power filter
strategy is the combination of tuned RL-passive filter and
small rated active power filter is the cost effective current
compensating devices. There are various control techniques
employed for the shunt hybrid active power filter strategy are
based time domain and frequency domain approaches are
revised in these literature survey. The extension synchronous
reference frame control technique produces the switching
sequence of the active power filter [5].
The organization of these papers as follows. The basic
introduction for power quality problems and shunt hybrid
active power filter strategy is discussed here. The system
configuration of the shunt hybrid active power filter strategy
ISSN: 2231-5381
is modeled in section II. The extension synchronous reference
techniques based dc-link voltage regulation for shunt hybrid
active power filter strategy is designed and explained in
Section III. The simulation result of designed model is
analyzed in Section IV. The conclusion of the paper finds a
place in Section V.
II. SYSTEM CONFIGURATION
The system configuration of three phase, three wire shunt
hybrid active power filter strategy is shown in fig. 2. The
diode bridge rectifier based nonlinear load will produce
current harmonics to the transmission line. This current
harmonics are compensate by shunt hybrid active power filter
strategy, the hybrid filter is the combination of three phase
tuned RL passive filter and small rated voltage source inverter
based active filters are connected in series without
transformers.
This hybrid filter is connected parallel to the transmission
line at the point of common coupling (PCC). The tuned
passive filter will compensate fifth order harmonic frequency
and active filter will compensate all other higher order
harmonic frequency. This passive filter has an additional
function of power-factor correction [3],[4].
Fig. 1. System configuration of three phase shunt hybrid active power filter
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International Journal of Engineering Trends and Technology (IJETT) – Volume 20 Number 5 – Feb 2015
TABLE I
SPECIFICATIONS AND PARAMETERS OF THE SYSTEM
Supply Voltages VS
230V
Supply Frequency F S
50Hz
R,L tuned passive filter RF,LF
1Ω, 20mH
DC-Link capacitor CF
1600µF
DC-Link voltage Vdc
400V
Rectifier based R,L Load
7Ω, 20mH
i Lu , i Lv , and i Lw into two-phase currents i Ld5 and i Lq5 on the
reference frame rotating at the fifth-harmonic frequency ω5.
The fifth-harmonic currents not positive sequence but
negative sequence currents.
The fifth-harmonic currents present in the load currents
corresponds to dc currents i Ld 5 and i Lq5 that are extracted by
the two first order low-pass filters (LPFS) with the same
cutoff frequency as 16Hz. Then the feed forward current
references in steady state can be calculated by equation (4)
III. CONTROL STRATEGY
……..(4)
The control circuit of the three phase shunt hybrid active
power filter strategy is shown in fig. 1. In this control circuit
consist of three section, they are feedback control,
feedforward control, and DC-Link voltage control [10],[12].
A.
Feedback control
In this feedback control consist of three phase source current
isu, isv and isw are taken has inputs apply to d-q transformation.
The d1-q1 transformation converts three phase supply current
into two phase synchronous direct and quadrate axis current
id1-iq1.
…..(1)
The fundamental components of the three phase supply
current correspond to dc components into id1 and iq1, and
harmonic components to ac components. Two first order highpass filters (HPFS) with the same cutoff frequency of 50Hz
~
extract ac components i d1 and i~
q1 from id1 and iq1,
respectively. Then, the inverse transformation of d1-q1
produces their supply harmonic currents.
…(2)
The each harmonic current ishu, ishv, ishware amplified by
the feedback gain k will produced three phase feedback path
current reference I*AFb
*
IAFb  k. i sh
…… (3)
Then the two-phase reference currents i*d5 and i*q5 are
converted into three-phase reference currents I*Aff ,I*Bff ,I*Cff with
the help of inverse d-q
transformation.



sinωt 
cos ωt  
 I* 
Aff


* 
2π 
2π   i*d5




sin
ωt

cos
ωt




  * .......(8)
 I Bff 

3
3



 i q5
* 

2π 
2π 
 I Cff 


sin ωt   cos  ωt  
3 
3 

 
C.
Dc Link Voltage Control
The DC link voltage control is maintained constant by a
proportional and integral (PI) controller. The dc link capacitor
voltage is build up and regulated without any external power
supply. In order to meet the loss inside the active power filter
strategy, an amount of active power is required and generated
by producing a fundamental ac voltage controlled by the
active filter. Since a fundamental leading current flows
through the RL passive filter, the active filter should generate
a fundamental voltage that is in phase with this leading
current. As a result, the current reference ( Id1) obtained in
this control loop is added to the direct axis current component
Idh.

ki 
PI Controller = Verror   k p  s 


……(9)
Where, V error  Vdc  V*dc ,
kp – proportional gain,
ki – integral gain.
B.
Feed forward control
The feed forward control for the most dominant fifthharmonic current converters three-phase load currents
ISSN: 2231-5381
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International Journal of Engineering Trends and Technology (IJETT) – Volume 20 Number 5 – Feb 2015
Fig. 3. Supply voltage before compensation for operating condition I.
Fig. 4. THD analysis for supply current before compensation for
operating condition I.
Fig. 2. Extension synchronous reference frame control techniques.
IV. SIMULATION RESULTS
Fig. 5. Supply voltage after compensation for operating condition I
The simulation results are verified by using Matlab/
Simulink to verify the viability effectiveness of the proposed
shunt hybrid active power filter. The feedback gain of the
active filter is 1pu, and the dc-link voltage is 400 V. The
simulation results are analyzed for two different operating
conditions. The operating condition I is normal load condition
and operating condition II is load change conditions.
A.
Simulation results for supply voltage
In operating condition I, The performance analysis of
supply voltage for mitigating the harmonics are validated as
follows. In figure 3, 4, 5 and 6 Shows, the THD% of the
source voltage for before compensation is found to be 5.80%
whereas after compensation, the THD for the source voltage is
noticed to be 0.83%. From the analysis, with (SHAPFs)
85.68% of source voltage THD is reduced. In operating
condition II, the performance of load change conditions are
analysed for supply voltage has follows. From the figure 7, 8,
9 and 10 reprecent, the THD% of the source voltage for before
compensation is found to be 8.17% whereas after
compensation, the THD for the source voltage is noticed to be
0.80%. From this analysis, with (SHAPFs) 90.20% of source
voltage THD is reduced.
Fig. 6. THD analysis for supply current after compensation for operating
condition I.
Fig. 7. Supply voltage before compensation for operating condition II.
Fig. 8. THD analysis for supply voltage before compensation for operating
condition II.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 20 Number 5 – Feb 2015
Fig. 11. Supply current before compensation for operating condition I.
Fig. 9. Supply voltage after compensation for operating condition II.
Fig. 10. THD analysis for supply voltage after compensation for operating
condition II.
Fig. 12. THD analysis for supply current before compensation for
operating condition I.
TABLE II
REDUCTION OF THD ANALYSISOF SUPPLY VOLTAGE FOR BOTH
OPERATING CONDITION
Fig. 13. Supply current after compensation for operating condition I.
In Table II, expresses the comparative analysis of three
phase supply voltage THD for before and after compensation.
In operating condition I, the reduction THD levels are more
than 85% and in operating condition II, the reduction THD
levels are more than 90%.
B. Simulation results for supply current
In operating condition I, The performance analysis of
supply current for mitigating the harmonics are validated as
follows. In figure 11, 12, 13 and 14 shows, the THD% of the
source current for before compensation is found to be 42.69%
whereas after compensation, the THD for the source current is
noticed to be 4.88%. From this analysis, with (SHAPFs)
88.56% of source current THD is reduced. Fig. 16, 17, 18 and
19 will expreses, the THD% of the source current for before
compensation is found to be 30.91% whereas after
compensation, the THD of the source current is noticed to be
3.65%. From this analysis, with (SHAPFs) 88.19% of source
current THD is reduced. From the fig. 20, is observed that the
reference supply current is tracking with actual supply current
with good accuracy.
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Fig. 14. THD analysis for supply current after compensation for operating
condition I.
Fig. 15. Actual and reference current tracking for operating condition I.
Fig. 16. Supply current before compensation for operating condition II.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 20 Number 5 – Feb 2015
and reference DC – Link voltage (Vdc) is 30.75%. And
operating condition II is represent in fig. 23. shows the peak
overshoot value of actual and reference DC – Link voltage
(Vdc) is 5%.
Fig. 17. THD analysis for supply current before compensation for
operating condition II.
Fig. 21. Actual and reference dc-voltage for operating condition I.
Fig. 18. Supply current after compensation for operating condition II.
Fig. 22. Actual and reference dc-voltage for operating condition II.
TABLE IV
PEAK OVERSHOOT AND SETTLING TIME OF DC-LINK VOLTAGE
Fig. 19. THD analysis for supply current after compensation for operating
condition II.
Fig. 20. Actual and reference current tracking for operating condition II.
TABLE III
REDUCTION OF THD ANALYSIS FOR SUPPLY CURRENT FOR BOTH
OPERATING CONDITION
Three
THD analysis for operating
THD analysis for operating
phase
conditionI(%)
conditionII(%)
supply
Before
Afte Reducti
Before
After
Reduction
current
compe
r
on of
compens
of THD
nsation
THD
ation
Isa
42.69
4.88
88.56
30.91
3.65
88.19
Isb
42.79
4.61
89.22
30.96
3.93
87.30
Isc
42.70
4.35
89.81
30.91
3.82
87.64
In Table III, expresses the comperative analysis of three
phase source current THD for before and after compensation.
In operating condition I, the reduction THD levels are more
than 88% and in operating condition II, the reduction THD
levels are more than 87%.
Operating
condition
Peak
overshoot(%)
Settling
time(sec)
Operating
condition I
30.75
0.26
Operating
condition II
5
0.097
In Table IV, expresses the comparative analysis for peak
overshoot and settling time of DC-Link voltage for different
operating conditions are verified. In operating condition I, the
peak overshoot and settling times are very high when
compared to the operating condition II.
V. CONCLUSION
The shunt hybrid active power filter strategy for mitigation
of current harmonic produced by the non-linear load are
designed and analyzed for various operating condition. The
extension synchronous reference frame technique is designed
to control the dc-link voltage for the shunt hybrid active
power filter strategy.
The feasibility of the proposed strategy for the power
quality is demonstrated for various operating condition with
promising results. This algorithm has proved the technique for
realizes an acceptable power factor profile and reducing the
current harmonics. The technique fines simple in the sense,
that it does not involve any complicated topology.
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of dc-link voltage for operating condition I is shown in fig. 21.
From the obtained results, the peak overshoot value of actual
ISSN: 2231-5381
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