The research paper published by IJSER journal is about DPC-SWICHING TABLE control for PWM Rectifier With the function of an Active Power Filter Based on a Novel Virtual Flux Observer 1

ISSN 2229-5518

DPC-SWICHING TABLE control for PWM Rectifier With the function of an Active Power Filter Based on a Novel Virtual Flux Observer

A. DJERIOUI(1), K. ALIOUANE(2), M. AISSANI(2) , F.BOUCHAFAA(1)

Abstract – For improving the quality of the energy transfer from the power supply to the load, and reducing the harmful effects of the harmonics generated by nonlinear load. We propose a new multi-function converter (MFC) as an efficient solution to improve the power quality. This paper presents a new DPC strategy based on virtual flux Observer and switching table to control PWM rectifier achieving by this unit power fac tor and reducing the harmonic current of the non linear load. The good dynamic and static performance under the proposed control strategy is verified by simulation and experiment.

—————————— ——————————

owadays, harmonic pollution in electrical power systems due to nonlinear loads such as AC-to-DC power converters has

become a serious problem.

To eliminate or reduce harmonics in the power systems, a number of methods have been developed and put into practice. Active power filters and PWM rectifiers are two typical examples of these methods. The active power filter and PWM rectifier have basically the same circuit configuration and can operate based on the same control principle.

Therefore, we can design a power converter capable of both the active filter operation and PWM rectifier operation at the same time.

The aim of Virtual Flux (VF) approach is to improve the VOC [2]. Here it will be used for instantaneous power

estimation. The simplified representation of a three phase PWM rectifier system is given by Fig .2, where the phases of line are represented by the virtual induction motor.

Thus, and represent respectively the stator resistance and the stator leakage inductance of the virtual motor. are phase to phase line voltages induced by a virtual air gap flux. In another words the integration of the phase to phase Voltage leads to a virtual line flux vector in stationary coordintes (fig .3)

With these definitions :

Rectifier to supply DC power to its own load and, at the same time, operates as an active filter to supply to the AC line a compensating current equal to the harmonic current produced by the nonlinear load connected to the same AC line.

Where

f

*U *

U f dt

2 1

1

2 *U *

(1)

(2)

ab

*U *f

3 0

__ __3 *U*bc

This paper presents a new control method entitled direct power

control (DPC) strategy based on a virtual

flux observer and switching table to control PWM rectifier with the function of an active filter.

2

Uf αd t

f

(3)

————————————————

f

Uf βd t

1 0

i f

2 *i*a

(1) Laboratory of Instrumentation, Faculty of Electronics and Computer,

__ __

(4)

i f 3 3 3 i

University of Sciences and Technology Houari Boumediene, BP 32 El-Alia 16111

Bab-Ezzouar Algiers, Algeria. Tel/Fax: 021.247.187

(2)UER Electrotechnique, EMP, BP 17 Bordj-El-Bahri, Algiers, Algeria Fax:

+213 21 86 32 04

E-mail : alidjerioui@yahoo.fr, kam-ali@lycos.com, fbouchafa@gmail.com

2 b

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The research paper published by IJSER journal is about DPC-SWICHING TABLE control for PWM Rectifier With the function of an Active Power Filter Based on a Novel Virtual Flux Observer 2

ISSN 2229-5518

Fig. 1: Control of PWM Rectifier With ActiUvesuFaillltyerRincgaFnubnectnieognlected which gives

Vnet1

Vnet2

G

Vnet3

S1 S2

Rf-Lf Inet1

A

Inet2

Inet3

Irect

S3

urect

B

C

Iload

d

S4 S5 S6 M’

PWM rectifier

Fig .2. Simplified representation of a three phase PWM rectifier system

Us

L.if f

dt

(7)

1 1

1 *U *

*U *s 2

AM

2 2 *U *

(5)

With the complex notation, the instantaneous power can be obtained

BM

as follows

*U *s

3 0

3 3 *U * *

2 2

CM

P ReU .i

(8)

Virtual line flux vector line voltage vector, inductance voltage

Vector -line current vector

q ImU

.i *

The voltage equation can be written as

d

Where * denotes the conjugate line current vector can be calculated by the virtual flux

Us R.if

L.if f

dt

(6)

U d

d .*e *j d f *e *j *j*

e j d f e j j

f

(9)

dt f

dt f dt

f dt f

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The research paper published by IJSER journal is about DPC-SWICHING TABLE control for PWM Rectifier With the function of an Active Power Filter Based on a Novel Virtual Flux Observer 3

ISSN 2229-5518

Where f

denotes the space vector and φf its amplitude. For the

f *u *f .dt L.if *

(23)

virtual flux oriented d-q in coordinates (Fig.3.)

Using (8) and (9)

f

*u *f

.dt L.if

*U *f

*d* f

dt

*j d* f

dt

j j

(12)

According to equation (22) and (23),the integrator can be used to

estimate the virtual flux ,but the initial value of flux must be estimated firstly this makes simulation complex and DC offset could be produced easily [9].

The novel virtual line flux observer and the comparison of the

d

*U *.*i** f

d

i j f

i j

*j*

i

*ji *

observers are showed in fig 4 and fig 5 respectively, which distinctly

f f

dt

dt f

f f f f

shows that the novel algorithm responds faster than the traditional

control.

That gives:

*P *

d f

i f j

d f

i f j f .i f j f .i f

vc

N . N

dt

dt

(14)

+

s wc s wc

d

*q * f

i f

d

*j *f

i f

j

f .i f

*j*

f .i f

ic L

dt

dt

For sinusoidal and balanced line voltage the derivatives of the flux are null. The instantaneous active and reactive powers can be computed as:

ic L

v N N

PC ω fα .*i*fβ fβ .*i*fα

(15)

c .

s wc

++

s wc

qC fα fα fβ fβ

The Basic block scheme of the VF-DPC system is given by Fig.1. The converter voltages are estimated in the block as follows:

Fig 4 The novel virtual line flux linkage observer

The instantaneous active and reactive powers are observed in the block (power observer) by measurement of line current and the observation of the virtual flux components f , f .

*V *f

2

dc a

1 *S * *S *

The command reactive power

qref

and active power

pref

3 2

2

*V*

(16)

(delivered form the outer PI-DC voltage controller) values are compared

with the estimated (q) and p values, in reactive and active powers hysteresis controllers, respectively.

f

.U dc S b S c .

3

If (qref -q >Hq) , dq=1; Else , dq =0;

If (pref -p > Hp), dp=1;Else dp =0; (7)

Where U dc is DC link voltage and Sa Sb Sc switch states

Hp and Hq are the hysteresis band. Table I shows the switching table for VF-DPC control

Sp Sq θ1 θ2 θ3 θ4 θ5 θ6 θ7 θ8 θ9 Θ10 θ11 θ12

1 0 V6 V7 V1 V0 V2 V7 V3 V0 V4 V7 V5 V0

1 V7 V0 V7 V0 V7 V0

0 0 V6 V1 V2 V3 V4 V5 V6

1 V1 V2 V3 V4 V5 V6 V1

Table 1: SWITCHING TABLE

of converter. After that the virtual flux components are calculated from the (7)

With:V0(000),V7(111),V1(100),V2(110),V3(010),V4(011)V5(001), V6( 101).

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The research paper published by IJSER journal is about DPC-SWICHING TABLE control for PWM Rectifier With the function of an Active Power Filter Based on a Novel Virtual Flux Observer 4

ISSN 2229-5518

Fig 5 The comparison of the three observer.

θ8 θ7

θ9 θ6

θ10 θ5

θ11 θ4

θ12 θ3

θ1 θ2

Fig.6. PWM Rectifier With the function of an Active Power Filter experimental test bench.

Fig.3.Virtual flux plane 12 sectors

The figure 3 shows the 12 voltage sectors plane for switching table.

In this section, experimental results are shown to test the proposed

controller using a prototype. For this purpose, the three-phase two- level power converter of Fig. 6 has been developed, with a digital implementation of the control algorithm that has been executed in a TMS320lf2407-40 MHz which has two high-resolution analog to digital (A/D) converters (0.8µs-10bit) provide very fast processing for fixed point calculations.

TABLE II

ELECTRICAL AND CONTROL PARAMETERS FOR THE EXPERIMENTAL SYSTEM

resistance of reactors | 2.9 Ω |

inductance of reactors | 11 mH |

resistance of reactors | 2.5 Ω |

inductance of reactors | 7.5 mH |

resistance of line | |

inductance of line | |

dc-link capacitor | 4.7mF |

phase voltage (RMS) | 110 V |

Dc-link voltage | 300 V |

PWM rectifier load: | 110 Ω |

diode rectifier load: | 42 Ω |

The hysteresis band was fixed | 0.01 |

The electrical parameters of which are shown in Table II.

Fig 7. DC –link voltage variation

Fig 8. Operation of PWM Rectifier under grid current sag

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The research paper published by IJSER journal is about DPC-SWICHING TABLE control for PWM Rectifier With the function of an Active Power Filter Based on a Novel Virtual Flux Observer 5

ISSN 2229-5518

line current becomes almost sinusoidal as well as in phase with line voltage, which gives near-to-unity power factor.

As Fig. 10 shows, the virtual line flux and oriented angles switch

smoothly in the transient adjustment process, which indicates that the DPC control strategy of PWM rectifier has a fast dynamic performance and excellent output performance

Fig 9. PWM rectifier operation without filtering operation [line voltage (v ) and line current (i )].

Fig 10. Experiment waveforms of the novel virtual line flux observer.

Fig 11. From top to bottom load ac current ac source current and active filter current.

Fig 12. Ac source current harmonic spectrum versus frequency

Fig.7. Fig. 8. Fig 9. Presents the start up the PWM rectifier operation. It is noted the linear currents are sinusoidal and the control technique presents a very good dynamic behavior, Thais thanks to PI regulator behavior used control the DC-link voltage. Under APF operation, the

4. CONCLUSION

This paper has proposed Direct Power Control (DPC) strategy based on a novel virtual flux observer with switching table to control PWM rectifier. The obtained results show that this control has a good dynamics, and it offers sinusoidal line currents (low THD) for ideal and distorted line voltage and compensates automatically the reactive power part to improve the main power factor to unity, the three-phase voltage-type PWM rectifier having also the function of an active power filter has been investigated and its effectiveness has been confirmed using a three-phase diode bridge rectifier with a smoothing reactor as a nonlinear load.

[1] Benhabib M. C. and Saadate S.: A new robust experimentally validated phase-looked loop for power’ electronic control, EPE Journal, vol. 15, no. 3, pp. 36–48, August 2005 .

[2] Mariusz Cichowlas , Mariusz Malinowski , Josep Pou: ’ Active Filtering Function of Three-Phase PWM Boost Rectifier Under Different Line Voltage Conditions’ IEEE transactions on industrial electronics, vol. 52, no. 2, april 2005

[3] A. Chaoui, J.P. Gaubert, F. Krim, L. Rambault, Power quality improvement using DPC controlled three-phase shunt active filter, ScienceDirect (10.1016/j.epsr.2009.10.020)

[4] Malinowski M, Jasinski M, Kazmierkowski MP. Simple direct power control of three-phase PWM rectifier using space vector

modulation. IEEE Trans Indus Electron 2004;51(No. 2):447–54.

[5] A. Chaoui, J.P. Gaubert, F. Krim, L. Rambault, IP controlled three-phase shunt active power filter for power improvement quality, IEEE Industrial Electronics Conference IECON (2006) 2384–2389. [6]Malinowski M, Kazmierkowski MP,S. Hansen , Blaabjerg ,F, Marques GD. Virtual flux based direct power control of three-phase pwm rectifiers. IEEE Trans on

Indus, Electronics vol 37 ,pp,1019-1027 ,july 2001.

[7] A. Kheloui, K. Aliouane, K. Marouani, F. Khoucha’A Fully Digital Vector Control of Three Phase Shunt Active Power Filters ‘. IECON2002 International conference Elestronices pp,1-6, Nov- 2002 [8] Sugita T, Nezu K, Sato Y and Kataoka T 1996 , "A current-type PWM rectifier with active filtering function", IEEJ SPC- 96 (107),

11-20 ( in Japanese)

[9] heng,Zheng, Cong Wang” Research on Direct Power Control Strategy for PWM Rectifier” International Conference on Future Power and Energy Engineering 2010 IEEE DOI

10.1109/ICFPEE.2010.30

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The research paper published by IJSER journal is about DPC-SWICHING TABLE control for PWM Rectifier With the function of an Active Power Filter Based on a Novel Virtual Flux Observer 6

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2005 and 2009 respectively in Electrical Engineering from the Polytechnic School of Algiers (ex: ENITA), Algeria. Since

2009, He has been a lecturer researcher in the electrical engineering department of the

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1999, he joined the Electrical Engineering Department of USTHB. He is member in Solar and modeling laboratory. His current research interests are in the area of control power electronics and power quality.