Comparison of Control Strategies for Three-Phase Shunt

JKAU: Eng. Sci., Vol. 22 No. 2, pp: 129-150 (2011 A.D./1432 A.H.) DOI: 10.4197 / Eng. 22-2.7

129

Comparison of Control Strategies for Three-Phase Shunt

Active Power Filter Applications

Ahmad Mohammed Dabroom

Yanbu Industrial College, Yanbu Industrial City, Yanbu,

P.O.Box: 30436, Saudi Arabia

Abstract. This paper introduces a comparison of control strategies of

three phase shunt active filters by determining the reference

compensating current under different operating conditions; balanced,

unbalanced and distorted source voltages. The compared methods are

the instantaneous reactive power theory (p-q), the synchronous

reference frame method (d-q) and the proposed method that depends

on generation of needed compensation current components by adding

fundamental positive sequence detector forcing the supply current to

be sinusoidal at different condition of the supply voltage. The

simulation results are obtained using Matlab-Simulink software. The

Shunt Active Power Filter (APF) and its control methods have been

implemented as a prototype and tested through Digital Signal

Processor (DSP). The results show good performance of the

developed active filter with proposed control technique. Expermintal

and simulation results with non linear load in different operating

conditions are presented to confirm the validity of the proposed

tehnnique.

Keywords: Active power filter, Power factor, Harmonics, Reference

current extraction, DSP.

List of Symbols:

APF: Active Power Filter, HPF: High Pass Filter,

IRPT: Instantaneous Reactive Power Theory, (-):DC (average) component,

P: The instantaneous active power , (~):an oscillating (AC) component,

q: The instantaneous reactive power, is: Instantaneous supply current,

iL: Instantaneous load current, PF: power factor

PLL: Phase locked loop, THD: total harmonic distrotion

ic*: The reference line current of the active power filter

ic: The actual line current of the active power filter

130 Ahmad Mohammed Dabroom

1. Introduction

In a modern power system, the increase of loads and nonlinear

equipments required the compensation of the disturbances caused by

them. These nonlinear loads may cause poor power factor and high

degree of harmonics in the system. APF have the ability to adjust the

amplitude of the synthesized ac voltage of the inverters by means of

pulse width modulation or by the control of the dc- link voltage; thus

drawing either leading or lagging reactive power from the supply. APF is

a modern solution to power quality problems [1-3]

. Most APF's have been

designed on the basis of instantaneous reactive power theory (p-q theory)

to calculate the desired compensation current. This theory was first

proposed by Akagi and co-workers in 1984 [4]

, and has been subject to

various interpretations and improvments [5-7]

. Figure 1 shows, the

principle of the shunt active filter. The nonlinear load is connected to the

power system and is supplied by the non-sinusoidal current iL. The shunt

active power filter is connected in parallel to the mains, on the point of

common coupling PCC, and supplies the current harmonics ic needed to

maintain the source current sinusoidal. The control strategy for a shunt

active power filter is to generate the reference current ic* that must be

provided by the power filter to compensate reactive power and harmonic

currents demanded by the load. This involves a set of currents in the

phase domain, which will be tracked generating the switching signals

applied to the electronic converter by means of the appropriate closed-

loop switching control technique such as hysteresis current controller.

Traditionally active power filters are studied under sinusoidal and

symmetrically voltage conditions. This paper compares three control

methods: (a) Instantaneous Reactive Power (p-q) theory, (b) Synchronous

Reference Frame (d-q) method and (c) proposed method to obtain the

reference compensating currents under unbalanced and distorted supply

voltage conditions [8-12]

.

2. Active Power Filter Control Methods

Since shunt active power filters inject harmonic currents on the

network. An outer controller determines the reference harmonic currents

that should be injected compensation current [9-10]

.

Comparison of Control Strategies for Three-Phase Shunt… 131

A three phase voltage inverter with current regulation is then used

to inject the compensating current into the power line. There are some

different methods for implementing the detection of harmonic currents [13-15]

. These methods were studied in symmetrical conditions in the

literature. The aim of this paper is to qualitatively determine the

differences between three of those methods under different conditions of

main voltage.

2-1 Instantaneous Reactive Power Theory (IRPT)

Instantaneous Reactive Power Theory (IRPT), is known as the p-q

theory [5-6]

. This method uses Park Transform given in equation (1), to

generate two orthogonal rotating vectors (α and β) from the three phase

vectors (a, b and c). This transform is applied to the voltage and current

and so the symbol x is used to represent v or i. Assuming balanced three

phase loads the x0 term is not used.

Lf

PWM

Control

C

ic

iL is vs

Active filter

Control

ic

*

vs

iL

Fig. 1. Basic control of three-phase shunt active filter.

Vc


Figure 2 shows the block diagram for an active power filter based

on Instantaneous Reactive Power Theory (IRPT). The supply voltages

and load currents are transformed into α-β quantities (Eq.1). The

instantaneous power of the load consists of a DC (average) component (-)

and an oscillating (AC) component (~). The instantaneous active and

reactive powers p and q are calculated from the transformed voltage and

current as given in Eq.(2).

The compensating reference currents are calculated to compensate

the two terms:

1. The oscillating component of the instantaneous active power

2. The instantaneous reactive power (q)

So, the instantaneous active power (p) is filtered by high pass filter

(HPF) to pass only the AC components as shown in Fig.2. Then the

Fig. 2. Block diagram for an active power filter controller using Instantaneous Reactive

Power (p-q) Theory.

-

+

vsb

αβ

Transform.

VC*

p-q

Calc.

Eq.(2)

HP

F

+

Pref. q

Compensating

reference current

calculation ic*

Eqn.(3)

ica*

icb*

icc*

VC*

PI

Vc

PLO

SS.

+

iLb

iLa

iLc

vs

c αβ

Transform.

Eq.(1)

iα

iβ

vβ

vs

a

+


compensating reference currents are determined by taking the inverse of

Eq.(2) as given in Eq.(3).

The inverse Park transform is applied to icα* and icβ

*, this gives the

reference compensating currents in standard three-phase form, as shown

in Eq.(4).

Fig. 3. Principle synchronous reference frame (d- q) method.

2-2 Synchronous Reference Frame In this method

[9-11] as shown in Fig. 3, the load currents ( )

are converted to synchronous d-q coordinates according to park

transformation as given below in Eq.(5)

Where is angular position of Synchronous Reference Frame,

which is determined by the Phase locked loop (PLL) circuit in Fig. 3.

vs

i*Ca

dq

abc

PLL

HPF iLb

iLc

i*

Cb

i*

CC

iLa

dq

abc HPF


Each current component of id, iq that produced from Eq. (5) has an

average value or DC component (-) and an oscillating value or AC

component ( ~

) as given in Eq.(6).

To get the reference compensating current of shunt APF, the High

Pass Filter (HPF) is used to remove the DC component , from id, iq.

So that, the shunt APF compensate only oscillating value to cancel

harmonics and reactive power compensation. Then, the three reference

compensating current of shunt APF can be obtained from the inverse

transformation given in Eq. (5).

2.3 Shunt Active Filter with Proposed Control Method

The conventional instantaneous reactive power (p-q) theory is

inadequate under non-ideal mains voltage cases [6-7]

. In case of

unbalanced and distorted supply voltages, the sum of components

will not be constant [6-11]

, and oscillating value of instantaneous

real power and instantaneous imaginary power are unwanted components

of the power system. Consequently, the shunt APF does not generate

compensation current equal to current harmonics, and gives to mains

more load harmonics than required. In order to eliminate this drawback

and to decrease the total harmonic distortion (THD) to the desired level, a

new control algorithm is developed. In the proposed method, the

fundamental positive sequence detector is added to modify the p-q theory

for improving the compensation performance under all voltage

conditions. In this new strategy, the shunt active power filter is controlled

as it gives the full compensation of harmonics when the mains voltage is

distorted and/or unbalanced.

In these criteria, the non-ideal mains voltage is converted to the

ideal case by converting it to ideal sinusoidal shape by using the low-pass

filter in the d-q coordinates. Figure 4 gives a general overview of

proposed control strategy to calculate full compensation of shunt active

power filter. The principal difference between this proposed control

algorithm and the conventional instantaneous reactive power (p-q) theory


is the addition of the positive-sequence detector of mains voltage as

shown in Fig.4.

The signal Ploss is used as an average real power and is obtained

from the voltage regulator DC-link capacitor voltage is compared by a

reference value and the error is processed in a PI controller which is

employed for the voltage control loop. The controller acts in order to zero

the steady-state error of the DC-link voltage.

3. Hysteresis Band Current Controller

The actual active power filter line currents are monitored

instantaneously, and then compared to the reference currents generated

+

-

Capacitor voltage

regulator

Fig. 4. General overview of proposed control strategy.

va

vb

vc

PLL

Circuit

LPF

v

d

v

q

positive-sequence of mains voltages

detector

abc

dq LPF

abc

dq

αβ

Transform.

αβ

Transform.

Eq.(1)

iL

a iL

b

i

α

iL

c

i

β

vα1

v

β

Compensating

reference current

calculation ic*

Eqn.(3)

ic

a*

icb*

icc*

q

p-q

Calc.

Eq.(2)

HPF

VC*

PI

PLOSS.

+

Pref.

VC +

Va Vb Vc


by the control algorithm. In order to get precise instantaneous current

control, the current control method must supply quick current

controllability, thus quick response. For this reason, hysteresis band

current control for active power filter line currents can be implemented to

generate the switching pattern of the inverter. There are various current

control methods proposed for such active power filter [6-10]

, but in terms

of quick current controllability and easy implementation hysteresis band

current control method has the highest rate among other current control

methods such as sinusoidal PWM. Hysteresis band current control is the

fastest control with minimum hardware and software but even switching

frequency is its main drawback [12]

. The hysteresis band current control

scheme, used for the control of active power filter line current, is shown

in Fig. 5. It is composed of a hysteresis around the reference line current.

The reference line current of the active power filter is referred to as ic*,

and actual line current of the active power filter is referred to as ic. The

hysteresis band current controller decides the switching pattern of active

power filter. The switching logic is formulated as follows:

If ica < (i∗ca −HB) upper switch is OFF and lower switch is ON for leg

“a” (SA= 1). If ica > (i∗ca +HB) upper switch is ON and lower switch is

OFF for leg “a” (SA= 0). The switching functions SB and SC for phases

“b” and “c” are determined similarly, using corresponding reference and

measured currents and hysteresis bandwidth (HB).

4. Simulation Results

The purpose of the simulation is to show the effectiveness of the

different control strategies for shunt active power filter and in reducing

the harmonic pollution produced on the load side under different mains

ic* +

-

ic

Fig. 5. Hysteresis band current controller.

Switching

Pulses

Error


voltage cases, including ideal mains, unbalanced, and distorted voltage.

The presented simulation results were obtained by using Matlab-

Simulink software for a 3-phase 3-wire power distribution system with a

3-leg shunt APF and three phase diode bridge rectifier is connected as a

nonlinear load. The parameters of this simulated system are reported in

Appendix (A).

4.1 Case1: Ideal Mains Voltage

Figure 6 shows the simulation results of line current and its

spectrum before compensation in case (1) for ideal mains voltage.

Figures 7, 8 and 9 show the simulation results with the p-q method, d-q

theory and proposed method respectively for the shunt APF under the

case of ideal mains voltage. The figures show source current is after

compensating with the supply voltage vs and compensating current ic

compared with its reference current ic*. Also, the spectrum of source

current is after compensation has been cleared. As can be seen from

waveforms the source current after compensation became sinusoidal and

in phase with three-phase mains voltages. The results in case of balanced

main voltages condition using three methods are feasible. Table 1

illustrates the total harmonic distortion (THD) of source current after

compensation with shunt APF, and power factor value (PF) of each

method under ideal main voltages condition.

t(s)

i L a

bc

(A)

0.95 0.96 0.97 0.98 0.99 1-30

-20

-10

0

10

20

30

(b) Three-phase load currents (source

currents) before compensating

v S a

bc

(V)

t(s) 0.95 0.96 0.97 0.98 0.99 1-400

-200

0

200

400

(a) Three-phase ideal mains voltage

0.95 0.96 0.97 0.98 0.99 1-40

-20

0

20

40

(c) Load current ( iLa) before

compensation and phase voltage (vsa)

i La (

A)

, v s

a (

V)

t(s)

vsa

iLa

Fig. 6. Case (1) Ideal (balanced) mains voltage condition.

F(Hz) 0 100 200 300 400

0

5

10

15

20

25

(d) Spectrum of load current ( iLa) before

compensation

i La (

A)


(a) Source current ( isa) after compensating and phase voltage (vsa)

0.95 0.96 0.97 0.98 0.99 1-40

-20

0

20

40 vsa

isa

t(s)

i sa(A

) ,v

sa(A

)

0 100 200 300 4000

5

10

15

20

(b) Spectrum of source current ( isa)

after compensating

F(HZ)

i sa(A

)

Fig. 7. p-q theory performances after compensation in case ideal mains voltage condition.

(c) Compensating current (ica) and its

reference and error between them

0.95 0.96 0.97 0.98 0.99 1-15

-10

-5

0

5

10

15

Err

or

icaref

,ica

t(s)

i care

f (A

) , i c

a (A

) (v

)

vsa

isa

0.95 0.96 0.97 0.98 0.99 1-40

-20

0

20

40

(a) Source current ( isa) after


t(s)

i sa (

A)

, v s

a (

V)

vsa

isa

Fig. 8. (d-q) theory performances after compensation in case ideal mains voltage.

(c) Compensating current (ica) and its reference and error between them

0.95 0.96 0.97 0.98 0.99 1-15

-10

-5

0

5

10

15

t(s)

i care

f (A

) , i c

a (A

) (v

)

icaref

,ica

Err

or

0 100 200 300 4000

5

10

15

20

(b) Spectrum of source current ( isa)

after compensating

F(Hz)

i sa (

A)


Table 1. Harmonic content and power factor under ideal mains voltage.

iL is p-q is d-q is prop.

THD% 20.88 1.825 1.527 1.013

PF 0.7871 0.9574 0.965 0.978

From the figures and Table 1, it is observed that with ideal mains

voltage, all the strategies are approximately equivalent and able to satisfy

the IEEE-519 Standard harmonic current limits [15]

.

4.2 Case (2): Unbalanced Mains Voltage

In this case, the three phase voltages source are unbalanced, where the

phase voltages vsa is less than the other phases (vsa = 200 r, vsb = 220 r.m.s,

vsc =220 r.m.s) as shown in Fig. 10-a. Figures 10(b,c,d) show the line current

and its spectrum before applying the shunt APF. It can be noted that, the

levels of triple harmonic of source currents spectrum are added before

compensation (Fig. 10-d) under unbalanced voltages conditions.

0.95 0.96 0.97 0.98 0.99 1-40

-20

0

20

40

(a) Source current ( isa) after compensation and phase voltage (vsa)

t(s)

vsa

isa

i sa (

A)

, v s

a (

V)

0 100 200 300 4000

5

10

15

20

(b) Spectrum of source current

( isa) after compensation

F(Hz)

i sa (

A)

Fig. 9. Proposed method simulation results in case ideal mains voltage.

0.95 0.96 0.97 0.98 0.99 1-40

-20

0

20

40


reference and error between them

t(s)

icaref

,ica

Err

or


Figures 11, 12, 13 show the simulation results with the p-q method, d-

q theory and proposed method respectively for the shunt APF under this.

Where the waveforms depicts the source current is and its spectrum after

compensating. Also the compensating current ic compared with its reference

ic* and the error between them are shown in Fig. 12-c, d respectively.

The harmonic contents reparation, before and after compensation

using p-q theory, d-q method and proposed method under unbalanced

voltages conditions is resumed in Table 2. It is shown clearly that with

comparing the frequency spectra, only the proposed method cancels most

of harmonics in the source current but in other methods the source

current after compensation still contains harmonics.

0.95 0.96 0.97 0.98 0.99 1-400

-200

0

200

400

(a) Three-phase unbalanced mains voltage

t(s)

v S a

bc

(v)

0.95 0.96 0.97 0.98 0.99 1-30

-20

-10

0

10

20

30

(b) Three-phase load currents (source

currents) before compensation

t(s)

i La

bc

(A)

0.95 0.96 0.97 0.98 0.99 1

-40

-20

0

20

40

vsa

iLa

(c) Load current ( iLa) before compensation and phase voltage (vsa)

t(s)

i La (

A)

, v s

a

(V)

Fig. 10. Case (2) unbalanced mains Voltage condition.

0 100 200 300 4000

5

10

15

20

(d) Spectrum of load current ( iLa) before

compensation

F(Hz)

i La (

A)


0.95 0.96 0.97 0.98 0.99 1-40

-20

0

20

40 vsa

isa



t(s)

i sa (

A)

, v s

a (

V)


reference

0.95 0.955 0.96 0.965 0.97 0.975 0.98 0.985 0.99 0.995 1-15

-10

-5

0

5

10

15

t(s)

i care

f (A

) , i c

a (A

) (v

)

icaref

ica

F(Hz)

i sa (

A)

0 100 200 300 4000

5

10

15

20



Fig. 11. p-q theory simulation results in case of unbalanced mains voltage condition.

0.95 0.955 0.96 0.965 0.97 0.975 0.98 0.985 0.99 0.995 1-1

0

1

2

3

4

5

(d) Error between compensating

current (ica) and its reference

t(s)

0.95 0.96 0.97 0.98 0.99 1-40

-20

0

20

40

t(s)

i sa (

A)

, v s

a (

V)

vsa

isa

(a) Source current ( isa) after compensation and phase voltage

(vsa)

0 100 200 300 4000

5

10

15

20



F(Hz)

i sa (

A)

Fig.12. d-q method simulation results in case of unbalanced mains voltage condition.

0.95 0.96 0.97 0.98 0.99 1-2

0

2

4

6



t(s)

(c) Compensating current (ica) and

its reference

0.95 0.96 0.97 0.98 0.99 1-20

-10

0

10

20

t(s)

i ca

ref (

A)

, i c

a (A

) (v

)

ica

icaref


The harmonic contents reparation, before and after compensation

using p-q theory, d-q method and proposed method under unbalanced

voltages conditions is resumed in Table 2. It is shown clearly that with

comparing the frequency spectra, only the proposed method cancels most

of harmonics in the source current but in other methods the source

current after compensation still contains harmonics.

Table 2. Harmonic content and power factor under unbalanced mains voltage.

iL is p-q is d-q is prop

THD% 24.45 7.8724 7.813 1.3

PF 0.727 0.8234 0.831 0.938

4.3 Case (3): Distorted Balanced Mains Voltage

To investigate the system performance under worst conditions of

harmonic content, three phase distorted voltages are used in the simulation.

Consider the mains voltage have dominant the 5th and 7

th harmonic

components. For this case, the distorted three-phase main voltages are

expressed by Eq. (7)

0 100 200 300 4000

5

10

15

20

(b)Spectrum of source current

( isa) after compensating

F(Hz)

i sa (

A)

0.95 0.96 0.97 0.98 0.99 1-40

-20

0

20

40


its reference

t(s)

i care

f (A

) , i c

a (A

) (v

)

icaref

,ica

0.95 0.96 0.97 0.98 0.99 1-40

-20

0

20

40

vsa

isa

(a) Source current ( isa) after compensating and phase voltage (vsa)

t(s)

i sa (

A)

, v s

a (

V)

Fig. 13. Proposed method simulation results in case unbalanced mains voltage condition.

0 0.2 0.4 0.6 0.8 1-50

0

50

100

150



t(s)


Where V5=V1/5 and V7=V1/7

Figures 14, 15, 16 and 17 show depict simulation results in case distorted mains

voltage. It can be seen from these figures that the performance of the p-q

algorithm for this case that is shown in Fig. 15 is not qualified because the

supply current after compensating has 17% THD level. This current after

compensation has sinusoidal waveform and improved to 2.3% of THD level

for d-q method as shown in Fig. 16. In the proposed method as in Fig. 17,

there is more reduction in harmonic distortion level; the supply current after

compensation (Fig. 17-c) is in phase with positive sequence component of

the supply voltage (vsa+) therefore, the performance of the proposed method

is better than that of the conventional p-q theory and d-q method. Table 3

presents summaries of simulation results for this case.

0.95 0.96 0.97 0.98 0.99 1-400

-200

0

200

400

(a) Three-phase distortion mains voltage

t(s)

v sa

(V

)

i La,b

,c (

A)

0.95 0.96 0.97 0.98 0.99 1-30

-20

-10

0

10

20

30

(b) Three-phase load currents (source currents) before

compensation

t(s)

Fig. 14. Case (3) distortion mains voltage condition without compensation.

F(Hz) 0 100 200 300 400

0

5

10

15

20

25

(c) Spectrum of load current ( iLa) before compensation

i La (

A)

(7)


0 100 200 300 4000

5

10

15

20



F(Hz)

i sa (

A)

Fig. 16. d-q method simulation results in the

case distorted mains voltage.

0.95 0.96 0.97 0.98 0.99 1-15

-10

-5

0

5

10

15

(c) Compensating current (ica) and its reference

t(s)

i care

f (A

) , i c

a (A

) (v

)

t(s)



0.95 0.96 0.97 0.98 0.99 1-50

0

50

i sa (

A)

, v s

a (

V)

vsa

isa

0.95 0.96 0.97 0.98 0.99 1-50

0

50



t(s)

i sa (

A)

, v s

a (

V)

vsa

isa

i sa (

A)

0 100 200 300 4000

5

10

15

20

25



F(Hz)

Fig. 15. p-q theory simulation results in the case distorted mains voltage.

0.95 0.96 0.97 0.98 0.99 1-20

-10

0

10

20


its reference

i care

f (A

) , i c

a (A

) (v

)

t(s)

icaref

ica


Table 3. harmonic content and power factor under distortion mains voltage.

iL is p-q is d-q is prop

THD% 26.32 17.8 2.3 1.4

PF 0.727 0.7914 0.891 0.946

5. Experimental Tests

The experimental arrangement has been set up and tested in the

laboratory as shown in Fig. 18 . The three-phase shunt active power filter is

achieved with a voltage source inverter (VSI) which contains three-phase

IGBT. The nonlinear load was a three-phase bridge rectifier with resistive

load. The proposed control strategy is implemented using digital signal

processor DSP (DS1104) manufactured by DSPACE Company and

developed under the integrated development environment of MATLAB-

SIMULINK software delivered by the MATHWORK. The supply voltages

(vsa,vsb), the load currents (iLa,iLb), the compensating currents of active filter

(ica,icb) and dc capacitor voltage of active filter (Vc) are input signals to the

DSP board through its ADC interface. The outputs of DSP are gating pulses

for the IGBT’s of the shunt active power filter through its DAC interface.

Figure 19 depicts the experimental test results of the prototype for proposed

0.95 0.96 0.97 0.98 0.99 1-400

-200

0

200

400

(a) positive sequence component of mains voltage

t(s)

v sa, b

,c+

(V)

0.95 0.96 0.97 0.98 0.99 1-400

-200

0

200

400

vsa vsa+

(b) positive sequence component

and its mains voltage

t(s)

v sa

+ ,

v sa

(V

)

t(s)

v sa

+ (

V)

,isa

(

A)

0.95 0.96 0.97 0.98 0.99 1-40

-20

0

20

40

(c) source current (iS) after compensating and

positive sequence component of mains voltage

vsa+

isa

(d) Spectrum of source current ( isa) after

compensation

0 100 200 300 4000

5

10

15

20

F(Hz)

i sa (

A)

Fig. 17. Proposed method simulation results in the case distorted mains voltage.


method under a three-phase rectifier load in case of unbalanced and distorted

mains voltage. The various waveforms show the positive sequence

component of mains voltage in case of distortion mains voltage condition

(Fig.19-a). Figure 19(b) shows the three-phase supply current before

applying the shunt active power filter. The supply current after

compensating of phase (a) superimposed with fundamental positive-

sequence component of the supply voltage is shown in Fig.19(c). The

reactive power (Q) before and after compensating is presented in Fig. 19(d)

where the supply current was found nearly sinusoidal and synchronous with

the mains voltage after compensation. It indicates the feasibility of the

implemented prototype under this condition. Through experimental results,

it is revealed that the supply currents after compensation were found to be

sinusoidal and in phase with the fundamental positive-sequence component

of the supply voltage, which was consistent with the simulation shown

above. For this test, the outcome indicates that the proposed method is useful

for the active filter studies and it indicates the effectiveness of the proposed

controller for shunt APF under this condition.

Fig. 18. Experimental arrangement setup of shunt APF using DSP.

Lf

PC with Matlab

Simulink 7.1

C

ic

iL is vs

va

6 Gating Signals

Switching function

(NA,NB,NC)

Base drive circuit

vb

iLa iLb

VC

ica icb

DSP board

(1104)

ADC

DAC


Fig.19(g). Compensating current

(ica) and its reference.

Fig. 19(a). Experimental result; positive

sequence component of mains

voltage in case distortion mains

voltage condition.

Fig. 19(b). Experimental result; Three-

phase load currents (source

currents) before compensating.

Fig. 19(d). Experimental result; source

currents after compensation and

phase voltage.

vs

a+ i

s

a

Fig. 19(e). Experimental result; reactive

power (Q) before and after compensation.

Q before

compensating Q after

compensating

Fig. 19(f). Experimental result; Three-

phase compensating currents.

Fig. 19(c). Experimental result; Three-phase

source currents after compensating.


6. Conclusion

A comparative analysis of three control strategies for three-phase

shunt APFs has been presented. The comparison has been studied under

three cases, including ideal mains voltage, unbalanced three-phase mains

voltage, and distorted mains voltage conditions. An experimental shunt

APF has been carried out on DSP to explore the advantages and practical

implementation with the proposed control strategy. The simulations and

experimental results have proven good performances and verify the

feasibility of the proposed algorithm, and it is most effective for all

source voltages conditions. Active power filter, based on the proposed

theory, gives satisfactory operation in the harmonic compensation and

improving the input power factor even when the system phase voltages

are unsymmetrical and distorted.

References

[1] Ozdemir, Engin, Kule, Murat and Ozdemir, Sule, "Active Power Filter for Power

Compensation Under Non-Ideal Mains Voltage", The 11th Mediterranean Conference on

Control & Automation, Rhodes-Greece,June 2003, pp:1225-1231.

[2] Montero, Maria Isabel, Cadaval, Enrique Romero and Gonzalez, Fermin Berrero

"Comparison of Control Straegies for sunt Active Filter in Three-Phase four Wire System",

IEEE Trans. On Power Electronics, 22(1):229-236, Jan.(2007).

[3] Xu, Y., Tolbert, L. M., Chiasson, J. N. and Peng, F. Z., “Dynamic response of active filter

using a generalized nonactive power theory,” Proc. IEEE IAS Annu. Meeting, Oct. 2005,

pp: 1225–1231(2005).

[4] Akagi, H., Kanazawa, Y. and Nabae, A., “Instantaneous reactive power compensators

comprising switching devices without energy storage components”, IEEE Trans. Ind. Appl.,

IA-20(3): 625–630, May/Jun. (1984).

[5] Watanabe, Edson H., Aredes, Mauricio and Akagi, Hirofumi, "The P-Q Theory For Active

Filter Control: Some Problem and Solutions", Journal of Control and Automatic, 15(1): 78-

84, March (2004).

[6] Afonso, J., Couto, C. and Martins, J., “Active filters with control based on the p–q theory,”

IEEE Ind. Electron. Soc. Newslett., pp: 5–11, Sep. (2000).

[7] Soares, V., Verdelho, P. and Marques, G. D., “An instantaneous active and reactive current

component method for active filters”, IEEE Trans. Power Electron., 15(4): 660–669, Jul.

(2000).

[8] Akagi, H., Ogasawara, S. and Kim, H., “The theory of instantaneous power in three-phase

four-wire systems: A comprehensive approach”, Proc. IEEE IAS Annu. Meeting, pp: 431–

439(1999).

[9] Peng, F. Z., Ott, G.W. and Adams, D. J., “Harmonic and reactive power compensation based

on the generalized instantaneous reactive power theory for three-phase four-wire systems,”

IEEE Trans. Power Electron., 13(6): 1174–1181, Nov. (1998).


[10] Aredes, M. and Watanabe, E. H., “New control algorithms for series and shunt three-phase

four-wire active power filters”, IEEE Trans. Power Delivery, 11(3):1649–1656, Jul. (1995).

[11] Nabae, A. and Tanaka, T., “Anew definition of instantaneous active-reactive current and a

power based on instantaneous space vectors on polar coordinates in three phase circuits,”

IEEE Trans. Power Delivery, 11(3): 1238–1243, Jul. (1996).

[12] Depenbrock, M., Staudt, V. and Wrede, H., “A theoretical investigation of original and

modified instantaneous power theory applied to four-wire systems”, IEEE Trans. Ind. Appl.,

39(4):1160–1168, Jul./Aug. (2003).

[13] Chandra, Ambrish, B.N., Bhim, Singh and Al. Haddad, Kamal, “An Improved Control

Algorithm of Shunt Active Filter for Voltage Regulation, Harmonic Elimination, Power–

Factor Correction, and Balancing of Nonlinear Loads”, IEEE Trans on Power Electronics,

15 (3): May (2000).

[14] Rafiei, M. R., Toliyat, H. A., Ghazi, R. and Gopalarathanam, T., “An optimal and

flexible control strategy for active filtering and power factor correction under nonsinusoidal

line voltages,” IEEE Trans. Power Delivery, 16( 2) : 297–305, Apr. (2001).

[15] Jeong, Seung-Gi and Woo, Myung-Ho, “DSP-Based Active Power Filter with Predictive

Current Control”, IEEE, Transactions on Industrial Electronics, 44(3): June (1997).

Appendix A

The parameters of the SAF

Input voltages vs = 380 volt Rectifier load resistance Rdc = 22Ω

Rectifier load current iL = 20 Amp. SAF inductor Lf = 4 mH

SAF DC link capacitor C = 250 µF SAF DC link voltage Vc = 750 volt


الموصل مقارنة طرق التحكم فى تطبيقات مرشح القدرة الفعال عمى التوازي

محمد دبروم حمدأ المممكة العربية السعودية ، ينبع،كمية ينبع الصناعية

يقدم البحث دراسة مقارنة لطرق التحكم فى مرشح القدرة .المستخمصساسى وذلك بحساب تيار التعويض الأ ،توازىعمى الالفعال الموصل

مثل جهد المصدر الثلاثى ،يل مختمفةغلممرشح تحت ظروف تشنة بين عدة وتمت المقار . جهد المصدر مشوه وغير متماثلو ،متماثلنظام المحاور –فاعمة المحظية النظرية القدرة غير : منها ،طرق

ستنباط تيار تعويضى من اوكذلك نظام تحكم مقترح ب ،التزامنية الدوارةمع المرشح كاف لجعل تيار المصدر جيبى وبدون مركبات توافقية

مما يحسن من ،ضافة مرشح لمترددات المنخفضة عند المصدرإقدم البحث دراسة مقارنة نظرية بين الطرق . ه الكمىمعامل التشو

مل غير خطى استخدام ح عمىمع تصميم نموذج عممي ،الثلاثسموب أوتطبيق .(ى حمل مقاومةذوجو تغدائرة توحيد ثلاثية الأ)

ستنباط تيار تعويضى من المرشح كاف لجعل تيار اب ،التحكم المقترح .طراف عند المصدرأ يووبدون مركبات توافقية عم ،المصدر جيبى

ظهرت النتائج العممية توافقا كبيرا مع النتائج النظرية مما يعطى أوقد فقيات فى تيار اقلال التو إسموب التحكم المقترح مميزات فى أ

.وكذلك تحسين معامل القدرة عند المصدر ،المصدر

Documents

Comparison of Control Strategies for Three-Phase Shunt