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THREE PHASE SHUNT ACTIVE FILTER WITH CONSTANT INSTANTANEOUS POWER CONTRO

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THREE PHASE SHUNT ACTIVE FILTER WITH CONSTANT INSTANTANEOUS POWER CONTRO Powered By Docstoc
					International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING &
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME
                             TECHNOLOGY (IJEET)

ISSN 0976 – 6545(Print)
ISSN 0976 – 6553(Online)                                                         IJEET
Volume 4, Issue 4, July-August (2013), pp. 245-254
© IAEME: www.iaeme.com/ijeet.asp
Journal Impact Factor (2013): 5.5028 (Calculated by GISI)
                                                                             ©IAEME
www.jifactor.com




          THREE PHASE SHUNT ACTIVE FILTER WITH CONSTANT
             INSTANTANEOUS POWER CONTROL STRATEGY

                                   *
                                       Mr.R.J.Motiyani1, *Mr.A.P.Desai2
                               1
                                  Department of Electrical Engineering,
             S.N.Patel Intitute of Technology & Research Centre, Umrakh, Surat, India
                                2
                                  Department of Electrical Engineering,
             S.N.Patel Intitute of Technology & Research, Centre, Umrakh, Surat, India


ABSTRACT

         This paper discusses development of the matlab simulation of three-phase shunt active filter
for non-linear rectifier load with constant instantaneous power control strategy. The shunt active
filter with constant instantaneous power control strategy compensates the oscillating real and reactive
power of the nonlinear load; it guarantees that only a constant real power p (average real power of
load) is drawn from the power system. Therefore, the constant instantaneous power control strategy
provides optimal compensation from a power flow point of view even under non-sinusoidal or
unbalanced system voltages.

Keywords: Pulse Width Modulation (PWM) converter, Generalized Fryze current control strategy.

1. INTRODUCTION

The Shunt Active Filters generally consist of two distinct main Block;

The PWM converter
The active controller

        The PWM converter is responsible for power processing in synthesizing the compensating
current that should be drawn from the power system. The active filter controller is responsible for
signal processing [2]. It determines the instantaneous compensating current reference in real time
which is continuously passed to the PWM converter. Fig.1 shows the basic configuration of a shunt
active filter for harmonic current compensation of a specific load.



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                                    i   s                                               i   L




                                                                    i   C




                                                              L             V       i   L




                                                      *
                                                  i   C




                            Fig.1 Basic configuration of a shunt active filter

2. ACTIVE FILTER CONTROLLERS

        The control algorithm implemented in the controller of the shunt filter determines the
compensation characteristics of the shunt active filter. There are many ways to design a control
algorithm for active filtering. Certainly; the p-q theory forms a very efficient basis for active filter
controllers [2].

Following are the different control strategies:
    • Constant instantaneous power control
    • Sinusoidal current control
    • Generalized Fryze current control

3. ACTIVE FILTERS FOR CONSTANT POWER COMPENSATION

        The constant power compensation control strategy for a shunt active filter was the first
development based on the p-q theory and was introduced by Akagi et al.in 1983[1].The principle of
this compensation method are described in fig.1.In terms of real and reactive power, in order to draw
a constant instantaneous power from the source, the shunt filter should be installed as close as
                                                                                      %
possible to the nonlinear load. It should compensate the oscillating real power p of this load [3].
Hence, the shunt active filter should supply the oscillating portion of the instantaneous active current
of the load, that is,

Oscillating portion of instantaneous active current on the α axis i α p ;
                                                                      %



                                        =      vα (− p )
                                                     %
                               iα   %
                                    p         2           2

                                            vα + v β                            1

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International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME


Oscillating portion of instantaneous active current on the β axis i β p ;
                                                                      %




                                           =
                                                  v β (− p )
                               iβ      %
                                       p            2
                                                         %       2

                                               vα +vβ
                                                                                        2

        The reason for adding a negative sign to the real power in the above equations is to match
them with the current directions adopted in fig.2. If the shunt active filter draws a current that
produces exactly oscillating power ( − p ) of load. The power system would supply only constant
                                          %
portion of real power ( p ) of load. In order to compensate oscillating power ( − p ), which implies an
                                                                                  %
oscillating flow of energy, the dc capacitor of the PWM converter must be made large enough to
behave as energy storage element, to avoid large voltage variations.

Following the instantaneous reactive current            i   aq
                                                                 and i β q on α and β   axis.

Instantaneous reactive current on the α axis            i   aq




                                       =      v α (−q )
                              iα   q            2           2

                                           vα + v β                                         3

Instantaneous reactive current on the β axis            iβ      q




                                       =     −v α (−q )
                              iβ   q            2           2

                                           vα + v β                                         4

        Note that the total reactive power being compensated is − q = − q − q . The reason for the
                                                                                %
negative sign is the same as explain for the real oscillating power compensation. Contrarily for
compensation of oscillating power ( − p ), compensation of the total reactive power ( −q ) does not
                                        %
require any energy storage element.
        If the shunt active filter compensates the oscillating real and reactive power of the load, it
guarantees that only a constant real power p (average real power of load) is drawn from the power
system. Therefore, the constant instantaneous power control strategy provides optimal compensation
from a power flow point of view, even under non-sinusoidal or unbalanced system voltages [2].

4. CONTROL BLOCK DIAGRAM

        Fig.2 shows control block of constant instantaneous power strategy of three phase shunt
active filter. Three phase instantaneous voltages and currents phases of balanced or unbalanced
source in the abc-reference frame is converted into instantaneous voltages and currents on the αβ 0 -
axis [7].The Clarke Transformation and its inverse transformation of three-generic voltages are given
by,


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                                     1  1
   v                              1 −   −  v a                    v
                      v α  2 
                                                                         α
        a
                                      2   2  
   v                   =                   v                   v
        b
                      v β 
                            3      3    3   b
                                                                         β
                                                                                             p = vαiα + v β i β
   v    c                       0 2 − 2   v c 
                                            
    i   a
                                    1   1                          i   α                 q = v β i α − vα i β
    i                            1 −    −  i a 
        b             i α  2      2   2                         i   β
    i   c              =                  i 
                      i β  3 
                                   3    3   b
                                0 2 − 2  i c 
                                           
                                                                                                         p           q
                  +                                       +          + p
    V       ref




                               −                     p    loss
                  V   DC

                                                                                        −1
                                          p+ p
                                          %        loss
                                                                 −q
                                                                                                                             *

                                                                             i
                                                                                 *
                                                                                                                       i   ca
   vα                    *
                                                − p + p 
                       i cα  = 2 1 2 v α v β  
                                                     %
                                                                                 cα
                                                                                       *      1    0                     *

                                                                                      i *  2  1                       i
                                                                                 *
                                                          loss 
                                                                             i                            *
   v                                                                                                   3  i cα 
                                                                                         ca                                  cb
                        *  v + v  v β −v α   − q                           cβ
                                                                                                −
                       i cβ  α β 
    β
                                                                                   i cb  =            *               *

                                                                                       *  3  2 2  i cβ             i   cc

                                                                                      i cc             
                                                                                              − 1 − 3 
                                                                                                 2
                                                                                                      2




                      Fig.2 Control block for the constant instantaneous power control strategy

                                              1           1       1 
                                               2           2       2  
                               v                                     v
                                0       2                1       1   a
                               v α  =        1          −       −  v b                               5
                                        3                2       2
                                                                       
                               v β                       3        3  v c 
                                              0                 −
                                                          2        2 




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International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME

                                     1                      
                                               1         0 
                                      2                      
                     v a                                      v
                              2    1            1       3   0
                     v b  =                 −              
                                                          2  v α 
                                                                                                 6
                                3     2           2
                     v                                        vβ
                      c            1            1        3 
                                              −        −    
                                      2           2       2 

       Similarly,three-phase generic instaneous line currents,           i i
                                                                         a     b
                                                                                   and   i   c
                                                                                                 can be transformed on
the αβ 0 axes by
                                     1         1         1 
                                      2         2         2  
                     i                                      i
                      0       2               1         1   a
                     i α  =         1        −         −  i b                               7
                              3               2         2
                                                              
                     i β                      3          3  i c 
                                     0                 −
                                               2          2 

and its inverse transformation is

                                     1                       
                                                  1       0 
                                      2                       
                     i a                                       i
                              2    1             1       3   0
                     i b  =     
                                3     2
                                               −
                                                    2
                                                               
                                                           2  i α 
                     i                                         iβ
                      c            1             1        3 
                                              −         −    
                                      2            2       2                                   8

       One advantage of applying the αβ 0 thransformation is to separate zero-sequence
components from the abc-phase componets.As per p-q Theory,it is defined in three-phase systems
with or without a neutral conductor.Three instantaneous powers-the instantaneous zero-sequence
power p ,the instantanous real power p ,and the instantanous phase voltages and line currents on the
        0

αβ 0 axies as

                     p                            0  i 0 
                      0  v 0
                                           0
                                                          
                      p =0             vα        v β  i α                                   9
                                                       
                      q  0
                                        vβ       − v α  i β 
                                                         
                     

      These two powers have constant values and a superposition                                        of   oscillating
compoents.Therefore,it is insteresting to separate p and q into two parts:




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International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME


Real power:                                                                 p= p+ p
                                                                                  %
Imaginary power:                                                            q = q + q
                                                                                    %
                                                                                    Averege Oscillating
                                                                                    powers   powers

                A dc voltage regulator should be added to control strategying a real implementation as shown
in fig.2.In fact, a small amount of average real power(                                                                           p        loss
                                                                                                                                                   ) must be drawn contiously from the
power system to supply switching and ohmic losses in the PWM converter.Otherwise,this energy
would be supplied by dc capacitor which would dicharge contiously.The power converter of the
shunt active filter is a boot-type converter.It means that the dc voltage must be kept higher than the
peak value of the ac-bus voltage in order to guarantee the controllability of the PWM current
control.Fig.2 suggests that the real power of the nonlinear load should contiously measured and
                                                              %
separated into its average real power ( p ) and oscillating ( P ) parts.This would be the fuction of the
block named “selection of the powers to be compensated” .In a real implementation,the sepation of
        %
 p and P from p is realized through a low-pass filter. Reference currrents i *C a , i * b and i* for
                                                                                         C        Cc

switching of IGBTs’PWM invetor is found from inverse Clarke Transformation.The switching
pattens of IGBT’s are found by comparing of reference currents and contionously sensed currents
from lines.

5. SIMULATION



                                                                              V                                         Id
     Discrete,
  Ts = 5e-005 s.                                                                                                                  pulses
                                                                            Goto1
                                                                                                                        Vabc
                                                                                                                                                               Scope2
      powergui                                                                                                               Rectifier
                                     measurements
                                                                                                                             Control
                                                                                                                                                   A                                                          Scope
                                                                                                                                                           +
                                                                                         A            A
                                                                                                                                                                                  i
                                                                                         B            B                                            B                            + -
                                                                                         C            C                                                    -
                                                                                                                                                   C                    Current Measurement
                                                                                       Three-Phase
                                                                                    Parallel RLC Branch                                            rectifier
            A                                              Vabc                                                                                                                                      h
                                                       A
  neutral   B                                              Iabc                      I

            C                                                                     Goto
                                                       B      a
   SOURCE
                                                              b
                                                       C
                                                              c
                                                      Three-Phase
   Ground2                                          V-I Measurement
                                                                                                                                           Conn1
                                                                                                                                                                                               +
                                                                                                                                                                                                 v
                                                                                                                                           Conn3                                               -
                                Scope3                                                                                                                                                 Voltage Measurement1
                                                                                                                                           Conn5                                                                      Scope5

                                         A    a                                                                                          Subsystem1
                                                                      In1
                                         B    b                                                   B

                                         C     c                      A

                   Subsystem2    Three-Phase Breaker                                         GROUND
                                                                      C
                                                                                                      SHUNT ACTIVE FILTER
                                                                             Subsystem
                                                                                                                    i
                                                                                                                  + -

                                                                                                          Current Measurement1
                                                                                                                                                         Scope1




                                                                                                                    Ground1


  Fig.3 Matlab simulation of shunt active filter supplying non-linear load of rectifier with constant
                               instantaneous power control strategy
                                                                                                          250
International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME


             1
            i ref




                                                                                          g
                                                                                          1



               2
            im eas




                                Fig.4 Subsystem of hysterisis block

                                 -K-

                                 Gain
                                                           -K-
                                                                                              2
                                 -K-                       Gain8                          Ialpha
                                 Gain1
                                 -K-

                                 Gain2



                                                                                                   3
                                 1
                                                           -K-                                    Ibeta
                                 Gain3
                                                           Gain9
                                     -.5

                                     Gain4
        1
     Vabc                            -.5

                                     Gain5                                                        1
                                     -K-                                                          I0
                                                           -K-
                                     Gain6                 Gain10

                                     -K-

                                     Gain7

                          Fig.5 Subsystem of Clarke Transformation block


6. TESTS AND RESULTS

        Results of Matlab simulation shown in fig.3 of three shunt active filter supplying non-linear
load of rectifier with constant instantaneous power control strategy are shown as following figures.
Input source of this simulation is used as three phase programmable voltage source which parameters
(voltage=220 V (line to line), frequency=50Hz) with internal resistance as RCL series branch with
resistance r=0.1ohm and inductance of 0.000010H.Line between source and load as non liner load as
three phase rectifier with RL circuit is of inductance of L=0.4mH.Matab simulation has non-linear
load as three phase rectifier with RL circuit which parameters are r=20 ohm and L= 0.4mH.Fig.6
shows voltage with value of aprroximate180 volt applied to three phase rectifier from lines from
source voltages. Fig.7 shows the load current per phase of nonlinear three rectifier with RL load.
Balanced or unbalance source can supplied with three phase active filter with constant instantaneous
power control strategy to non linear load as shown Fig. 8 the constant average active power(P) and
reactive power (Q) of non linear rectifier with RL load. Fig.9 shows the load current per phase of
nonlinear three rectifiers’ circuit.Fig.10 and 11 show output voltage and current of three phase
rectifier circuit supplied to RL Load.




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        Fig.6 Load 3-phase voltages or input voltages of three rectifier supplied RL Circuit




              Fig. 7 Load current per phase of Non linear three rectifier with RL load




Fig. 8 Constant Active Power (P) and reactive power (Q) of Non linear three rectifier with RL load




          Fig. 9 Load currents or input currents of Non linear three rectifier with RL load

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International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
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            Fig. 10 Output voltage of three phase rectifier circuit supplied to RL Load




             Fig.11 Output current of three phase rectifier circuit supplied to RL Load

7. CONCLUSION

        Here in, Simulation of three phase shunt active filter supplying to non linear load with
constant instantaneous power control is successfully simulated using Matlab.It has been realized that
the three phase shunt active filter with Constant instantaneous power strategy compensates the
oscillating real and reactive power of the load; it guarantees that only a constant real power p
(average real power of load) is drawn from the power system. Hence, the constant instantaneous
power control strategy provides optimal compensation from a power flow point of view even under
non-sinusoidal or unbalanced system voltages.

8. REFERENCES

 1.   H.Akagi,Y.Kanazawa,and A.Nabae, “Instantanous Reactive Power Compensator comprising
      Switching Devices Without Energy Storage Components”, IEEE Transactions on Industrial
      Applications,vol.IA-20,no-3,1984,pp.625-630.
 2.   S.J.Jeong and T.Endoh”Control Method for a Combined Active Filter System
      Employing,”IEEE Transactions on Industrial Electronics, vol 41, no.3, 1994, pp.278-284.
 3.   H.Akagi,Y.Kanazawa,and A.Nabae,”Principles and Compensation Effectiveness of a
      Instantaneous Reactive Power Compensator Devices, “in Meeting of the Power
      Semiconductor Converters Reserchers-IEE-Japan,SPC-82-16,1982(in Japanese)
 4.   L.Gyugyi and E.C.Straycula,”Active ac Power Filters, “in Proceedings IEEE industrial
      Applications Annual Meeting, vol.19-C, 1976, pp.529-535.
 5.   L.S.Czarnecki,”Power Related Phenomena in Three-Phase Unbalanced Systems,”IEEE
      Trans.Power Delivery,vol.no.3, July 1985,pp.1168-1176.
                                                253
International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 4, July-August (2013), © IAEME

 6.    M.Routimo,M,Salo,and H.Tuusa,”comparision of voltage and current source shunt active
       power filters,”in conference records IEEE-PESC 2005,pp-2571-2577.
 7.    H.Akagi,”Trends in Active Power Filters,” in EPE’95-European Conference Power
       Electronics Appl.,vol.0,Sevilla,Spain,sep.1995,pp.0.017-0.026.
 8.    N.G.Hingorani,”Power Electronics in Electric Utilities: Role of Power Electronics in Future
       Power Systems,”Proceddings of IEEE,vol.76,no.4,April,1988
 9.    N.G.Hingorani,”High Power Electronics and Flexible AC Transmission System,” IEEE Power
       Engineering Reviews,July 1988.
 10.   Dr. Leena G, Bharti Thakur, Vinod Kumar and Aasha Chauhan, “Fuzzy Controller Based
       Current Harmonics Suppression using Shunt Active Filter with PWM Technique”,
       International Journal of Electrical Engineering & Technology (IJEET), Volume 4, Issue 1,
       2013, pp. 162 - 170, ISSN Print : 0976-6545, ISSN Online: 0976-6553.
 11.   o. ucak, i. kocabas, a. terciyanli, design and implementation of a shunt active power filter with
       reduced dc link voltage.
 12.   Mohd Abdul Lateef, Syed Maqdoom Ali and Dr.Sardar Ali, “Reactive Power Aspects in
       Reliability Assessment of Power Systems”, International Journal of Advanced Research in
       Engineering & Technology (IJARET), Volume 4, Issue 3, 2013, pp. 124 - 131, ISSN Print:
       0976-6480, ISSN Online: 0976-6499.
 13.   Mahavir Singh Naruka, D S Chauhan and S N Singh, “Power Factor Improvement in
       Switched Reluctance Motor Drive using PWM Converter”, International Journal of Electrical
       Engineering & Technology (IJEET), Volume 4, Issue 4, 2013, pp. 48 - 55, ISSN Print : 0976-
       6545, ISSN Online: 0976-6553.


BIOGRAPHIES


                         R. J. Motiyani has received the M.E degree in Electrical Power
                         Engineering from M. S. University, Baroda, and Gujarat in 2005. Currently
                         he is working with S.N.Patel Institute of Technology & Research Centre as
                         Associate Professor in Electrical Engineering Department.




                         A.P. Desai has received the B.E degree in Electrical Engineering from
                         VNSGU, Surat; Gujarat in 2008.He has received M.E.degree in M.E.
                         (electrical engineering) from Shantilal shah Engineering college, Bhavnagar
                         in 2013. Currently he is working with S.N.Patel Institute of Technology &
                         Research Centre as Assistant Professor in Electrical Engineering
                         Department.




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