Open Access Simulation and Application of Power System Stabilizer on Power System Transient Stability

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1 Sn Orr for Rprint to 8 Th Opn Elctrical & Elctronic Enginring Journal, 04, 8, 8- Opn Acc Simulation an Application of Powr Sytm Stabilizr on Powr Sytm Tranint Stability Ang Li * School of Elctrical Enginring, Shaanxi nivrity of Tchnology, Chaoyang Roa, Hanzhong, Shaanxi, 7000, China Abtract: Thi papr introuc th working principl an th mathmatical mol of aitional powr ytm xcitation control-powr Sytm Stabilizr (PSS. Through tablih a typical ingl machin-infinit bu powr ytm imulation mol, w imulat th ynchronou gnrator tranint oprational charactritic following a vr iturbanc. Th imulation rult how that th PSS can not only ffctivly incra th ytm amping, but alo improv oprational charactritic of th gnrator, conirably nhanc powr ytm ynamic an tranint tability. ywor: Low fruncy ocillation, MATLAB imulation, powr ytm tabilizr, tranint tability.. INTRODCTION Th ynchronou gnrator xcitation ytm play an important rol in avancing powr ytm rliability an tability. Enhancing th prformanc of xcitation vic ha bn acknowlg a on of th mot fficint an conomic mtho to improv gnrator tability. Convntional PID control ba on claical control thory ha bn wily u, but PID control ajut only by trminal voltag viation can not provi atifactory amping charactritic, pcially for th control of larg gnrator unit, that th amping charactritic will prouc pontanou lowfruncy ocillation, thratning th powr ytm tability []. Th ffctiv maur to olv th contraiction btwn voltag rgulation accuracy an ynamic tability i th aitional powr ytm tabilizr (PSS, which can ffctivly nhanc th amping of powr ytm, thrby improv it tatic an ynamic tability.. WORING PRINCIPAL AND MATHEMATICAL MODEL OF THE PSS.. Low-Fruncy Ocillation Mchanim Larg ynchronou gnrator xcitation ytm i gnrally compo of two part by th xcitation powr unit an th xcitation control unit. B ajut in accoranc with th gnrator trminal voltag viation, th xcitation control unit, alo known a automatic voltag rgulator (AVR, i th main xcitation controllr. With th rgulation accuracy of th AVR i gtting highr an highr, th rpon of th xcitation powr i alo growing fat. Fat xcitation ytm can in improv th ynchronization toru, thrby nhancing tranint tability of th ytm in firt ocillation cycl. Howvr, th fat xcitation ytm i gnrally ngativ fback ytm with high magnification, which ha littl ffct on th ytm ocillation amping aftr th firt wing cycl, an omtim vn ruc ytm ocillation amping. If th ytm prnt ngativ amping proprti, fat xcitation ytm (pcially high magnification i to incra ngativ amping, which worn th opration tatu of th ytm []... Mathmatical Mol of th PSS PSS i an aitional xcitation control. It nc i to provi an aitional ignal to incra amping toru of th gnrator xcitation ytm. Thi control ignal can provi poitiv amping ffct, without affcting th voltag rgulation function of th voltag rgulator an th ability of maintaining th gnrator trminal voltag lvl, thrfor, alo known a aitional xcitation control. For th purpo to incra th capability of prvnting powr ytm from low-fruncy ocillation, PSS can u th gnrator rotor p (!, ytm fruncy (!f, acclrating powr ( P m! P, lctrical powr (!P, an th combination of th ignal a input ignal []. For th output V PSS of PSS i a upplmntary xcitation control ignal, with Phillip-Hffron mol [4] hown a Fig. (, w know th powr viation i:!p T T 0 T + (T 0 + T + (!, ( /4 04 Bntham Opn

2 Simulation an Application of Powr Sytm Stabilizr Th Opn Elctrical & Elctronic Enginring Journal, 04, Volum 8 9 Δ T m 4 P P Vt Vt I 0 + ΔE I0 + c in δ0 + c coδ0 + E + c coδ0 Q0 c in δ0 + Whr i th link-ractanc btwn th gnrator an th ytm, an c i th trminal voltag of th infinit bu, othr ar paramtr of th gnrator an oprating variabl of th ytm. Obviouly, th valu of ~ rflct th gnrator oprating conition an th connction with th ytm (which ha nothing to o with th opration conition, apparntly oprating conition an gri paramtr will affct th valu of ~. If th armatur raction i nglct (i.., 4 0, w gt th impl rult:!p ΔT + + T M ( T 0 T + (T 0 + T + (!, ( + Subtituting j! into ( an thn it can b parat into ral an imaginary part, w gt: D 0 Δω 4 +!P a! + D a!#, (4 ω + T Δδ + V PSS Fig. (. Tranfr function of ingl machin-infinit bu powr ytm. Whr: a ( +! T 0 T ( +! T 0 T + (T 0 + T i ynchronou toru cofficint, an D a (T 0 + T! 0 i amp- ( +! T 0 T +! (T 0 + T ing toru cofficint. Du to th paramtr charactritic of non-alint pol gnrator ( > > > an alint pol gnrator ( > >, uually 4 ar poitiv. In havy-uty, it i clar that with powr angl incra, will b ngativ an D a < 0, thu th ytm iffrntial uation charactritic root i poitiv, th ytm may b ngativ amping ocillation. For convntional xcitation ytm, bcau <<! T 0 T, an T 0 i conirabl (4~8, thn th amping cofficint can b approximatly writtn a: D a (T 0 + T! 0 (! T 0 T +! (T 0 + T (T + T 0! 0 (+! T (! T 0 + #! 0! T 0 (+! T ( Thu, th gratr th valu of, th gratr th ngativ amping, an th ocillation will b mor riou. With th valu of T incra, th ngativ amping can b ruc, o that th ocillation wakn. Howvr, th valu of T cannot b too big, othrwi th ocillation tim will b xtn, that i not conuciv to th tability of th ytm. For th valu of T ( T! 0 i vry mall in fat xcitation ytm, o th ngativ amping i nhanc, rulting in a low-fruncy ocillation. Thu PSS i gnrally intall in fat xcitation ytm. Whn i larg, th amping cofficint can b approximatly writtn a: T 0 ω0 0 + ( Da ω ( T, ( It can b n that whn i gratr than a crtain valu, th nominator incra fatr than th molcul, th ngativ amping will cra thu fat xcitation ytm can b tabl vn if th gain of AVR vry larg. From Fig. (, th ytm lctromagntic toru can b writtn a:!t [ [ + T ( ( + T 0 (+ T ]!# 4 ( + T T, (7 ]!# ( + T 0 (+ T +

3 0 Th Opn Elctrical & Elctronic Enginring Journal, 04, Volum 8 Ang Li Fig. (. Simulation mol of th ingl machin-infinit bu powr ytm. Lt! b a inuoial prturbation, aum th angular vlocity i!, thn!!# j$!#. Taking j! into th abov uation, w obtain:!t [ 4 ( + j#t j#t ]!$ ( + j#t 0 (+ j#t +, (8 Taking Δ ω a input ignal, th tranfr function of PSS i G PSS ( G PSS! PSS, th aitional amping toru i:!t E G ( + T 0 (+ T E + E PSS (!#, (9 E G $% G PSS $% PSS!# If th laing pha! PSS pha!, thr ar: i ual to th nominator in!t E G G PSS!#, (0 It can b n that th ΔT a a componnt bcau of PSS, which th am pha with Δ ω, thrby gnrating poitiv amping. Gnrally with incra,!t E bcom largr, that th PSS i bt to intall a aitional xcitation control ignal in high magnification xcitation ytm.. TRANSIENT STABILITY SIMLATION OF THE PSS.. Singl Machin-Infinit Bu Sytm Mol Through tablih a imulation mol of a typical ingl machin-infinit bu powr ytm, a hown in Fig. (, w imulat th ynchronou gnrator tranint oprating charactritic following a vr iturbanc. Th gnrator ytm conit of ynchronou gnrator an xcitation control ytm (AVR+PSS. Infinit ytm u thr-pha powr upply moul. In thi ca w aum that th mchanical powr input to th gnrator i contant. An th olvr algorithm aopt otb. i: If taking Δ ω a input ignal, th tranfr function of PSS P(S 0! %! + # $ + 0.0&! + % # $ +.4&, ( Th output limit ar %... Th Influnc of PSS upon Tranint Stability Th main cau laing intability unr grat iturbanc i th powr iffrnc (i.. acclrating powr btwn mchanical powr an lctromagntic powr of th gnrator, thu rucing th powr iffrnc i firt of all conir maur (uch a fat fault claring, xcitr control, fat cloing main valv tc.. On thi bai, th influnc

4 Simulation an Application of Powr Sytm Stabilizr Th Opn Elctrical & Elctronic Enginring Journal, 04, Volum 8 a Fig. (. Simulation curv of gnrator powr angl: (a without PSS, (b with PSS. b a Fig. (4. Simulation curv of gnrator rotor p: (a without PSS, (b with PSS. b of th PSS to powr ytm tranint tability ha bn tui. Th fault of thr-pha hort circuit occur at at th ha of th tranmiion lin, an th fault clar at t.0. Powr angl an rotor p curv of gnrator with or without PSS ar rpctivly hown in Fig. ( an Fig. (4. For vr iturbanc uch a thr-pha hort-circuit, th rarch rult how that whn PSS i not uipp, pit applying th maur uch a rmoval th fault rapily, th ytm till lot it tability. Thrfor, whn PSS i appli, th amping of th ytm will b rmarkably nhanc an th ytm tability will b improv. Th PSS mak th gnrator to prouc aitional lctromagntic powr, nhanc th amping of th ytm, o th firt angl ocillation back wing amplitu cra, ignificantly improv th oprating charactritic of gnrator. ualitativ analyi th tability of th xcitation control ytm. From th imulation rult w can that th PSS can provi ufficint poitiv amping, ffctivly ovrcom th ngativ amping of th AVR, an ignificantly improv th tranint tability of powr ytm. But PSS for th rol of th gr of powr ytm tability pn mainly on two apct: on i th it whr th PSS houl b intall; th othr i th paramtr of PSS wr optimiz []. In complx multi-machin powr ytm, th choic of th mol an configuration i uit complicat an important. If th choic i unrv, vn mak th low fruncy ocillation mor riou. CONFLICT OF INTEREST Th author confirm that thi articl contnt ha no conflict of intrt. CONCLSION Thi papr tak Δ ω a th input ignal to PSS a an aitional xcitation control, imulat th tranint proc of a ingl machin infinit-bu ytm in larg iturbanc, ACNOWLEDGEMENTS Th author gratfully acknowlg th financial upport from Hanzhong Municipal Burau of Scinc an Tchnology Fun (No. 0hzzx-.

5 Th Opn Elctrical & Elctronic Enginring Journal, 04, Volum 8 Ang Li REFERENCES [] W.B. Chu, J.M. Liu, J.Z. Liu, an L.. Tan, Moling an Simulation about Inclu Nw PSS of Excitation Sytm, Elctric Machin & Control Application, vol., pp. -9, 009. [].F. Wang, W.L. Fang, an Z.C. Du, Morn Powr Sytm Analyi. t. Scinc Pr: Bijing, 00, pp (in Chin. [] H.L. Yang, T.Y. Zhang, an J.J. Guo, Action of PSS on ytm tability an paramtr tablihmnt in fil rgulator, North China Elctric Powr, vol., pp. -4, 00. [4] M. Huang, an H.Y. Han, Th PSS paramtr optimization ba-on powr ytm oprating variabl, Elctric Powr, vol., pp. 9-, 007. [] F. Zhang, J.F. Li, W. Wang, H.P. Zhou, Z.H. iang, G.S. Y, an Y.P. Zhou, Th imulation of PSS an SVC to tability of lctric powr tranmiion ba on MATLAB, Elctric Switchgar, vol., pp. 40-4, 009. Rciv: Novmbr 0, 04 Rvi: January 07, 0 Accpt: January 0, 0 Ang Li; Licn Bntham Opn. Thi i an opn acc articl licn unr th trm of th Crativ Common Attribution Non-Commrcial Licn ( which prmit unrtrict, non-commrcial u, itribution an rprouction in any mium, provi th work i proprly cit.