shunt active power filter

1. SHUNT ACTIVE
POWER FILTERS
Under supervision of : Submitted By:
Mrs. Manjima Bhattacharya Shivangni sharma
(Dept. of Electrical Engg.) 15EE221
NIT PATNA M.Tech-PhD DD,POWER SYSTEM
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2. CONTENTS
 Introduction
 Harmonics
 Effects and It’s solution
 Filters
 SAPF
 Analysis techniques
 Different Blocks in SAPF
 Advantages
 Disadvantages
 Applications
 Conclusion
 References
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3. INTRODUCTION
 In these days use of non linear loads
has increased since the advancement
and easy controllability in electrical
power.
 This results in generation of current
harmonics and reactive power in
system network.
 Harmonics has several negative
effects.
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4. HARMONICS?
 Harmonics are the components where the frequency is an
integral multiple of fundamental frequency
 Harmonic distortion is measured by calculating
THD(Total harmonic distortion)
where I stands for current , h for harmonics
 According to IEEE Std 519-1992,current THD has to be
less than 5%
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5. EFFECTS AND It’s SOLUTIONS
 Harmonics can cause
 Overheating
 Voltage Distortion and Flickering
 Interference
 Different solutions are
 Capacitors
 Compensators
 Passive filters
 Active filters
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6. FILTERS
 Active Power Filters
1.Series Active Power Filter
• SeAPF is connected in series with the T.L
• Acts as a controlled voltage source
2.Shunt Active Power filter
• ShAPF is connected in parallel with the T.L
• Acts as a controlled current source
3.Unified power quality controller
• Combination of passive ,series and shunt filters
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7. SHUNT ACTIVE POWER
FILTER
 The principle of the shunt filter is to produce harmonic
currents equal in magnitude but opposite in-phase to those
harmonics that are present in the grid.
 Phase shift of the harmonic current is 180 degrees
 SAPF is a closed loop structure
 SAPF can compensate reactive power and can also
mitigate harmonics and distortions
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8. 8

9. SHUNT ACTIVE POWER
FILTER
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10. ANALYSIS TECHNIQUES
 Reference generation techniques
 To compensate harmonics , it is important to generate
compensating current reference
 P-Q theory
 Others includes dq0 , ANN..etc.
 Tracking Methodology
 To track reference current properly
 Hysteresis controller , PI controller , slide mode controller etc.
 Converter Topology
 Depending on type of loads , voltage…,performance indices
Such as ,THD ,efficiency , cost , reliability
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11. DIFFERENT BLOCKS IN
SAPF
 Instantaneous power calculation block
 Power compensation
 Reference current calculation block
 PWM converter
 DC voltage regulator
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12. INSTANTANEOUS POWER
CALCULATION
 The crucial part of SAPF which calculates the
compensation currents
 These currents are calculates using “P-Q theory.”
 This Constant power control strategy was the first strategy
developed for Active power filters by Akagi et al. in 1983
 This theory uses Clarke’s transformation which consists of
real matrix that transform three phase ‘V’ or ‘I’ into αβ0
stationary reference frames.
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13. CLARKE’S TRANSFORMATION
AND IT’S INVERSE
• For a 3-phase system without a neutral/ground, we can neglect the zero sequence
component to make the matrices as
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14. CONTINUED…..
 Using the Clarke’s transformation we can convert the
current and voltages into αβ frame and again back to abc
by inverse Clarke’s transformation
 We separate the apparent power into real and imaginary
parts using P-Q theory
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15. AVERAGE AND OSCILLATING
COMPONENTS
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•Mean value of instantaneous real power that is transferred from
source to load in a balanced way through abc coordinate . This is
the fundamental energy source to load.
•Alternating value of Instantaneous real power which is
exchanged between power source and load . As this not
contribute in energy transfer , this component must be
compensated . This is due to harmonic currents.
•Mean value of instantaneous Imaginary power exchanged
between source and load . Choice of compensation of this power
depends upon requirements . This is due to fundamental reactive
current.
•Average value of instantaneous imaginary power exchanged
between phases and load . This is also must be compensated.

16. These currents
and voltages
are taken as
inputs to the
filter from the
line or load.
Through
transformatio
n, we get the
real and
imaginary
power values
The power to be
compensated must
be selected i.e. 𝒑 etc.
The powers to be
compensated are given
input. The compensator
should draw exactly the
given amount of current
that produces the inverse
of powers that are drawn
by the load.
By applying Inverse
Clarke's
transformation, we
get the actual abc
coordinates which
can be applied to the
line again.
ACTUAL IMPLEMENTATION
OF P-Q THEORY IN SAPF

17. PWM CONVERTER
 Responsible for power processing.
 Consists of VSC or CSC , To force the PWM converter act
as a controlled voltage or current source
 VSC is made up of PE devices(GTO, IGBT…)
 PE devices are fired based on the APF currents
 APF currents can be calculated using Hysteresis
Controller method. 17

18. HYSTERESIS CONTROLLER
 Control the VSI through the PWM in a manner that the
output current of inverter then tries to track the reference
current fed to the hysteresis current controller which
works in a close loop
 A reference value is kept and is compared with the two
input of the controller
 Based on the error between the 2 inputs and the reference
value, signals are generated
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19. 19
Hysteresis current controller
>
<
If
If
Transistor switch off
Transistor switch on
If No change

20. DC VOLTAGE REGULATOR
 Determines the extra amount of power Ploss that causes an
additional flow of energy.
 This active power Ploss is then summed up to together
with are passed to calculation of reference current block
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21. ADVANTAGES
 Widely compensated harmonic spectrum
 Only one filter needed to eliminate all the unwanted
harmonics
 Improved stability of the power system due to the lack of
parallel resonance
 Its performance is dynamic and take into account the
changes in load
 It may also be programmed to eliminate specific number
of harmonics
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22. DISADVANTAGES
 This method is poor in compensation of harmonic
current if source voltages are not symmetrical.
 Instantaneous reactive power based approaches
require Large number of voltage and current
transducers
 Switching frequency of hysteresis controller is not
constant
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23. APPLICATIONS
 FACTS Devices
 Smart GRID systems
 HVDC converters
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24. CONCLUSION
 This method utilizes the P-Q theory to detect harmonic
wave and reactive load current efficiently, compensate the
harmonics and reducing the THD value
 This method is very important; it allows harmonic
currents and reactive power compensation simultaneously
 It injects compensation current in order to cancel the
harmonic component of load . So the source sees the N-L
load in parallel to APF together as an ideal resistor
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25. REFERENCES
 A. Bhattacharya, C. Chakraborty and S. Bhattacharya,
“Current compensation in shunt type active power filters,”
IEEE Industrial Electronics Magazine, vol.3, no.3, pp.38-
49, 2009.
 H. Akagi, “Utility applications of power electronics ” in
Conf. Proceedings of IPEC Yokohama 95, pp 19-22,1995.
 H. Akagi, “Trend in Active Power Line Conditioners ” in
IEEE Trans. On Ind. Electronics, Vol.9, N°3, pp. 263-268,
August 1994.
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26. THANK YOU
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