Design and implementation of single phase hybrid active power filter controller

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IEEE PEDS 2005

Design and Implementation

ofSingle-Phase Hybrid

Active Power Filter Controller

N. A.Rahim S.Mekhilef I.Zahrul

Dept. ofElectrical Engineering Dept. ofElectricalEngineering Dept. ofElectrical Engineering

UniversityofMalaya University ofMalaya Universityof

Malaya

50603Kuala Lumpur, Malaysia 50603Kuala Lumpur, Malaysia 50603KualaLumpur,Malaysia email:[email protected] email:saadeum.edu.my email:

[email protected]

Abstract-This paper presents a combination of a series active Starting from the use of discrete

analog

and

digital

powerfilterand a shunt passive filter.The shuntpassive filteris components, the progression is going to microprocessors, connected in parallel with a load and suppresses the harmonic micro-controllers and Digital Signal Processors (DSPs). It is currentproduced by the load, whereas the active filter connected possible to implement complex algorithm on-line for

the

in series to a source acts as a harmonic isolator between the control of active filter at reasonable cost.

This

development

sourceand load. For active filtercontrol,Sinusoidal Pulse Width

Modulation

(SPWM)

is

developed

and the modulation index is

has made

t

possilble

to use

dlfferent

control

algoroits

such

selectedby calculatingthe DC bus voltage of the active filter. The as,Proportional Integral (PI),variablestructurecontrol, fuzzy

PSpices,

Matlab/Simulink and MAX PLUS ll softwares are logic and neural nets for improving

the

dynamic and steady used for simulation and hardware implementation. stateperformanceofthe active filter. Witi this

improvement,

theactive filtersare

capable

of

providing

fast

corrective

action

Keywords:Activefilter,harmoniccompensation, power even withdynamically changing non-linear loads [3-4].

quality Active filter basically, is a voltage or current source PWM

inverter. It hasbeen studied and put into practical use because I. INTRODUCTION they have the abilityto overcome the disadvantages inherent Harmonic distortion can be classified as voltage harmonic in passive filters. The active filter of voltage or current source and current harmonic. The effects of voltage harmonic inverter has variable current or voltage source. It eliminates distortions are voltage sag, swell and fluctuation. The main

the

harmonics by

injecting

the compensating current or causes ofthis distortion are sudden loading of the system at voltage direct to the AC lines. The complete cancellation of the common coupling point, large neutral currents due to harmonics will be achieved if the filter generates the unbalance loading, improper grounding and etc [1]. These compensating current equal and opposite to the present effects result the voltage drops in supply line impedances, harmonics or compensating voltage in phase with the system. generation of earth-neutral voltage and interference in In practice, the ideal compensating would be achieved by the communication system. Process control system canoften lead different modulation method [4-6].

to data loss and malfiuctioning of protective relay. The Harmonic elimination by active power filter is entirely primary effects of current waveform distortions are power dependent upon te modulation method. The most useful factor reduction, poor utilization ofdistribution wiring

plant,

methods of modulation are carrier wave modulation andpulse high currentflow inthe neutral line of four-wire three-phase width modulation. In carrierwave modulationmethod, carrier system and thedangerousoverheatingof cable and etc [1-2]. wave modulationsuppresses the harmonic content to the small These current harmonicresultsanincreases in the level of rms amount by adjusting the magnitude and te frequency of supply current, power loss, heatingofequipment, increase the carrier wave. In order toreduce theharmonics,it is necessary reactivepowerdemand. [3]. to raise the carrier

frequency,

but it causes the more complex Harmonic problem can be minimized by the following control circuit, and it increases the switching loss. The PWM

threeways: such as the multi pulse scheme can solve the harmonic

i)Byadding passiveoractive harmonic filters to attenuate compensation problems, and multi pulse PWM active filter theharmonicproblems. has good characteristics of harmonic elimination. However, ii) The utilization of auto-transformer to the phase shift this filter needs the compensating source of constant currentor

section ofthe load in such a manner as to cancel low order voltage [3-6].

harmonics. A new Active Filter has been proposed in this paper on the

iii)

By

replacing

the

existing

power distribution basis of the combination of Active Power Filter and

passive

tansformers With the tansformer

iat

include

phase

shibted

elements suchascapacitor and reactor to eliminate

the

voltage

transformers

with-

transformer-that

and current harm onic of the load. As result the proposed

winingon heecodar an/ortha hae hgh eve of system can solve the problems

inherent

in

using

only the reactance between

the primary

and secondary windings. The passive filter. In addition active filter is much smaller in rating next

breakthrough

in active filter development has resulted

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II. PROPOSED TOPOLOGY

processed

signal

is extracted

by

comparing

DCbus

capacitor

The single line diagram of the Active Power Filter is voltage

with

a reference DC value. The error signal (difference shown in Figure 1. A

single-phase

voltage

source inverter is between the DC bus voltage and

the

DC reference voltage) is connected in series between the ac source anda

single-phase

processed by a Proportional, Integral and Derivative (PID) full bridge diode rectifier with a non-linear harmonics controllerfor stability.

producingload.This configuration is known asActivePower

Filter. Apassive filterisconnected inparallel before the load

S

ourc PWM

atthe loadend.

-

-Refer t Multelil

Fr . YSEMIMLEENATO

In thi confiuratin passve fiter byassesthe curenteracticlipeenainoCanre AcieFle controlwas _~~~~~~~~~~~~~~~~~~~~~Feuoc

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passiveelement an th AcSitive Flte act as avoltage AralFG) PAi nitgae ici I) hc

Passi8ve 9 cSinesgall

compensator

and

harmonic isolator between the sourc anda conssts arofanf e tsithoer galtesl

Trareormer~~~~~~~~A:v PIDto

loadphasevoltae to he lne.. ytemvoltagercomensdactionvis donerbyTeharonicisoltiofinjectingrthe

ise alon

donerLa

n- tables,RAM,flip-flopand pwiigothtcnb porMmeulinlo thW ilatrmnuatrConted

fudmntals compguatonet butsite forces toypasse

the current

Altracia

FPGAntto.o

nAtieFltrcnto a

harmonic component

throudigh thepassivned

filterThu

the

Forit the

implement

ation

n

ofer siusidaldPWMgram reguleare

pactive Filtermprovethd

e

fcivilterincaactrsis ofpassv

samligttchiqe is

used.)

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csarrieravecisrcompared)whith

filtenstr

and

the

powerfcisltoroftela byten

compnstigshe

suc n

th modulatng waveray mpfloitude*siemet

wae).Theraea,lootim

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ianufathrelo

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(POM.r sine

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Figure showsthe blck diaram forthe cotrol o an maimum,slokdarme logi gthesmotonitor itandiv generafitesr. iga

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ounter

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issthe

prmter fo the Figure 3 shows the top level schematic for PWM

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modulatingwave, which is obtainedby digital multiplication and the source current with outcompensation by Active and ofsine valuefromROMandacontrolsignal

(amplitude)

from passivefilter. Figure 4(b)representsthe harmonic

spectrum

of the closed

loop

control. The comparison between the carrier thesource current shown in

Figure4

(a),

whichwas

analysed

and

modulating

signal

hadtobe done ina manner that when by

MATHCAD

software and the total harmonic distortion is thecarriervalue is less thanorequaltothemodulating

signal

32.6%.

the PWM output level is high and when the carrier value is

greater than the modulating value the PWM output level is 400 low. The

comparison

isdone in every clock

pulses

thatmeans 20

inevery stepofcounting for carriervaluesas well asforthe X °_

ROM datavalue. This comparisontimefully depends on the

-2______

_______________________________0,05

.6 00 0.08 0.09

design ofPWM circuit and the main clock frequency.

__,2 _o.Q _o

00_OE_0.0

0OS .9 0

..~~~~~~~~~~~~~~~~v FiA o5B~

I

\ME

US

''

I I S\

i

1

_____________________________________________2______________ 7 iii- ---- - ;

----i1,02 Ot3 MO0. 0.05 0.0vr 007 038 0.09 0

(a)

Fundamentalcomponent

-i.-t~ : : -<, j t ! 503rdharmoniccomponent

-e __ _

,-

5tb

harmoniccomponent

Fig.3.PWMschemeusingrnnpIusllf ₀ _ _ j₅ -_LriIn_i_Llh₁₀ ₁₅ ₂₀I ₂₅ ₃₀ ₃₅I- ₄₀

The main clock frequency is generatedby aPhase Lock Harmonicorder loop (PLL). Thismain clock frequency, 9.83MHz isadjusted (b) precisely for the carrier frequency 19.2KHz.

In closed loop control the amplitude of the modulating _activeFig. 4:_{and passive}a) Simulated_{Filter (b)}source voltage and current_{Harmonic spectrum}without_of_sourcecompensation_current by

wave is determined bycomparingthe DC busvoltagewith a

DCreferencevoltage. Thedifferenceof thistwoDCvalues is Figure 5(a) and Figure 5 (b) illustrates the simulation converted todigital value and processed by a PID controller results for the source voltage and the current, and the

forstability. harmonic spectrum of the source current with the

The digital realization of PID controller is implemented compensation by the passive filter only. The total harmonic by bit serial algorithm. In PI) control proportionalrepresents distortion is 16%.

thegain ofa signal. The digital division andmultiplication is

used to represent the gain. Integration disappears the steady 400

state error ofa signal. To obtain the integration of a present

value,

it is added with the

integrated

value. The

derivative ofa

signal

is

widely

used in controller to

achieve

= °

---o---

---good dynamics. In digital realization, differentiator is the 20 _

---gradient

between two

samples.

To

implement

the difference _ ______ __._,_.

equation, a sample has to be passed in pipeline for one °0° Time 1

sampling period and then be subtracted from the current

sample.

Adder valuescan underflow or over

flow,

soitmust s -- /f ---

---be controlled

properly.

IV.SIMULATION

RESULTS

X---s~~~~~~~~~---

--

---J--

---

-

vl--

---1-rV. SIULfATIONRESULTS__

0.02 0.03 0.04 0.0 O06 0.07 0.08 0.09

The simulation results are obtained by simulating the Time

model shown inFigure 1byMATLAB/

SIMULINK.

Theplot

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100 r- -T f

*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~3 ...F n aet ac moet3---e---,I...

Fundamentalcomponent

2in~~~~~~T~~~~~** ... ..xi...

3dharmoniccomponent

~50

....4....

... ... ...

----5"hharmoniccomponent .

0 _._ _ -3 ' -' ', ' '--'--' ' i' -~~~~~~~~~~~~~' '. ~~' -'' ''~~~~"~~- >T:---rT

---00

10 20 30 40 ₃₀₀₂

002 0024O 002 o.o 0.03 0.032 0.4 0.03 oi 0.04

Harmonic order li

Fig.7. In-phase pattem of simulated voltage and current source

(b) (Scale:Forvoltage 1OOV/div,forcurrent 2A/div.)

Fig.5(a) Simulatedsourcevoltage and current after compensation by only

passivefilter(b)Harmonicspectrumofsourcecurrent XY plotrepresentthephase displacement andtherough

Figure6 (a) and Figure 6 (b) show the simulated source distortion idea about the two waves, if there is phase voltage and current, and the harmonic spectrum of source displacement between the two waves, the XY plot become currentafter compensation by active and passive filter and the elliptical inshapeandwithout phasedisplacement between the totalharmonic distortion is6.7%. waves, the

XY

plotbecomeas a straight line with minimum

Figure

7 shows the simulated

voltage

and current source distortion. For

harmonic

distorted wave theXY

plot

has no

Figure

7attemi

show e

axs,whimulatepredentstha

voltagee astandard shape. From the XY plot it is also possible to

wave pattern in same axis, which represents that the voltage measurethe phase displacement oftwowaves. and currentsourcearealmostin-phase.

4003 00 0I 00n 00 00 A00 '01 _'+. A ....

-Mo .,,,,,. .k , .W

0m.0 0.03 004

S-ft---ie---,\---e-~~~~~~~~~~~~~~---

0.05 0.0 0.07 0.08 009 01

...

1020.03 0.~~~~04O OS0 _Tim,eO O 0.07 O.OS 0.09

(a)

Fig.8.

XYplotofvoltageandcurrentsourcebeforecompensation

Figure 8 shows the XY plotof voltage and current source

so . = l without compensation andwithcompensation by active power

filter andpassive filter.

.4 - Fundamental component

V.CONCLUSION

Many configurations of active power filters are available

3dharmonic component to compensate the harmonic current, reactive power, neutral

current, and also the unbalance current ofthe

harmonic

load.

The proposed active power filter can compensate current harmonics components, reactive powerand also improves the power factor of the load. The results show the active filter L0 n0 er '5 |l l l lreduces the total harmonic distortion up-to 7.78%. Without

#iarmonic

order active and passive filter, 3d harmonic and

5th

harnonic

distortion was 37.98% and 6.47% respectably. After (b) compensationby active and passive filter both reduces to 5%

Fig.6 (a)Simulatedsourcevoltageandcurrentaftercompensation by active and 2.13%.

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REFERENCES

[1] Adil M-Zamil and D. A. Torrey. "A Passive Series, Active Shunt Filter for High Power Applications" IEEE Transactions on Power

Electronics, 16(1),

pp.101-109 January2001.

[2] HideakiFujita and hirofumi Akagi"Apractical Approach to harmonic Compensation in PowerSystems-Series connection of Passive and active

Filters",

IEEE Transactions on industry applications, Vol. 27, No. 6, pp. 1020 -1025November/Decemberl991.

[3] Chen Guozhu, Lu Zhengyu and Qian Zhaoming "A Novel Hybrid Active Power Filter with Two Passive Channelsforhigh Power Application",PowerElectronics Specialists

Conference,

PESC. 200, vol.

4,

pp. 1889

-1892.

[4] Sangsun Kim andP.Enjeti"A NewHybrid ActivePower Filter (APF) Topology" Applied power electronics conference and Exposition, 2001,APEC2001, Volume: 2, March2001,pp. 835-841.

[5] Chin-Yuan Hsu and Homg-Yuan Wu "A New Single-Phase Active Power Filter With Reduced Storage Capacitor" Power Electronics Specialists Conference, PESC '95, 1,202 -208.