Detailed Simulation of Voltage and Frequency Controller for Wind Generating System with Unbalanced Linear Load with Fixed Wind Speed

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1 Internatonal Journal of Scentfc and Research Publcatons, Volume, Issue, March 0 Detaled Smulaton of Voltage and Frequency Controller for Wnd Generatng System wth Unbalanced Lnear Load wth Fxed Wnd Speed Nnu Joy, Benny Cheran, Salce Peter Assstant professor, Dept of EEE, M.A College of Engneerng, Kothamangalam, Inda Professor, Dept of EEE, M.A College of Engneerng, Kothamangalam, Inda Professor, Dept of EEE, M.A College of Engneerng, Kothamangalam, Inda Abstract- Ths paper deals wth Voltage and frequency controller for wnd generatng system wth unbalanced lnear loads. The proposed system s modelled and smulated n MATLAB usng smulnk.the controller that controls both oltage and frequency of an asynchronous generator along wth ts mproement of power qualty. The proposed controller has bdrectonal acte and reacte power flow capablty along wth battery energy storage system by whch t controls the system oltage and frequency wth araton of consumer load. Index Terms- Battery energy storage system, solated asynchronous generator, oltage and frequency controller, wnd energy conerson system. T I. INTRODUCTION oday the need for renewable sources s ncreasng partcularly wnd.because wnd s the most promnent source of energy aalable. We can easly explot by usng asynchronous generator.squrrel cage nducton are low cost, robust and smple n ts constructon. Here employng a oltage and frequency controller for standalone wnd power generatng systems n order to mantan oltage and frequency. The proposed oltage and frequency controller s hang bdrectonal acte and reacte power flow capablty by whch t controls the system oltage and frequency wth araton of consumer loads and wnd.the performance s demonstrated usng standard MATLAB software. Here we can dscuss about detaled smulaton of ths scheme. II. SYSTEM CONFIGURATION Fg.. Schematc dagram of the proposed solated wnd energy system The complete off grd stand alone system wth asynchronous generator, wnd turbne, exctaton capactor, balanced/unbalanced, lnear/non-lnear/dynamc consumer loads and proposed controller s shown n Fg.. The proposed controller ncludes three-phase nsulated gate bpolar juncton transstor IGBT based oltage source conerter VSC along wth a battery at ts lnk. The controller s connected at the pont of common couplng PCC through the nter-facng nductor []. The exctaton capactor s selected to generate the rated oltage at no-load whle addtonal demand of reacte power s met by the controller. III. CONTROL SCHEME Fg..Schematc dagram of the proposed control strategy for an solated wnd energy system Fg demonstrates the control strategy of the proposed controller whch s based on the generaton of reference source currents. Reference source currents are hang two components one s reacte component for controllng the magntude of the generated oltage and other one s the acte component for regulatng the frequency of the generated oltage. The ampltude of acte power component of the source current s estmated by ddng the dfference of fltered load power and output of PI frequency controller to the ampltude of the termnal oltage. Multplcaton of wth n-phase unt templates yelds the n-phase component of reference source currents. These templates are, three-phase snusodal functons whch are dered by ddng

2 Internatonal Journal of Scentfc and Research Publcatons, Volume, Issue, March 0 the ac oltages by ther ampltude. To generate the reacte component of reference source currents another set of unt templates s dered from n-phase unt template and whch are 90 leadng from the correspondng oltages. The multplcaton of these templates and output of PI Proportonal Integral termnal oltage controller ges the reacte component of reference source currents.the sum of nstantaneous reacte and acte Components of currents ges the total reference source currents and these are compared wth the sensed source currents. The amplfed current error sgnals are compared wth fxed frequency 0 khz trangular carrer wae to generate the PWM swtchng sgnals for the deces of VSC. IV. MODELING OF THE CONTROL SCHEME Basc equatons of the control scheme of the proposed controller are as follows. A. Computaton of Acte Component of Reference Source Current Acte component of reference source current s estmated by ddng the dfference of fltered nstantaneous load power PLflter P and output of the PI frequency controller C to the V termnal oltage tm. The load power P L s estmated as by takng three-phase to two-phase transform la lb lc lb lc lb lc la lb lc 4 Instantaneous acte power s estmated as P L 5 It s fltered to achee ts component P Lflter. The frequency error s defned as f ern = f ref n - f n 6 Where f ref reference frequency 50 Hz n present system and f s the frequency of the oltage of an asynchronous generator. The nstantaneous alue of f s estmated usng phase locked loop PLL. At the th samplng nstant the output of frequency PI controller Pc s as P cn = P cn- + K pf {f ern -f ern- }+ K f f ern 7 Where K pf and K f are the proportonal and ntegral gan constants of the frequency proportonal ntegral PI controller. Then acte component of reference source current I dm s calculated as P LFlter P c I dm tm 8 The nstantaneous lne oltages at the termnals of an asynchronous generator la, lb and lc are consdered snusodal and ther ampltude s computed as Vtm { la lb lc } The unty ampltude templates are hang nstantaneous alue n phase wth nstantaneous oltage la, lb and lc, whch are dered as V la da Vlb Vlc V d tm b Vtm Vtm B. Computaton of Reacte Component of Reference Source Current Instantaneous alues of n-phase components of reference source currents are estmated as rda = I dm da,, rdb = I dm db, r = I dm The ac oltage error at the n th samplng nstant as V ern = V tmrefn V tmn Where V tmrefn s the ampltude of reference ac termnal oltage and V tmn s the ampltude of the sensed three-phase ac oltage at the termnals of an asynchronous generator at n th nstant. The output of the PI controller I qmn for mantanng constant ac termnal oltage at the n th samplng nstant s expressed as I qmn =I qmn- +K pa {V ern V ern- +K a V ern } Where K pa and K a are the proportonal and ntegral gan constants of the oltage proportonal ntegral PI controller alues are gen n Appendx. V ern and V ern- are the oltage errors n nth and n-th nstant and s the ampltude of quadrature component of the reference source current at n- th nstant.the nstantaneous quadrature components of reference source currents are estmated as I rqa = I qm qa,,i rqb =I qm qb,i rqc = I qm qc 4 where q a, q b and q c and are another set of unt ectors hang a phase shft of 90 0 leadng the correspondng unt ectors, and whch are computed as follows: db qa 5 da db qb 6

3 Internatonal Journal of Scentfc and Research Publcatons, Volume, Issue, March 0 q c da db 7 C. Computaton of Reference Source Current Total reference source currents are sum of n-phase and quadrature components of the reference source currents as rsa = rqa + rda 8 rsb = rqb + rdb 9 rsc = rqc + r 0 D. PWM Sgnal Generaton Reference source currents rsa, rsb and rsc are compared wth sensed source currents sa, sb and sc. The current errors are computed as rsaerr = rsa - sa rsberr = rsb - sb rscerr = rsc - sc These current errors are amplfed wth a gan K and the amplfed sgnals are compared wth fxed frequency 0 khz trangular carrer wae of ampltude to generate gatng sgnals for IGBTs of VSC of the controller. V. ANALYSIS AND DESIGN A.Desgn Of Three Leg VFC Parameters of VFCs are desgned for a -kw, 45-V, 50- Hz asynchronous generator-based standalone WECS. It s reported that for feedng reacte power n the case of 0.8-pf laggng reacte loads, an IAG requres 40 60% of the reacte power of the rated generated power. Therefore, the VAR ratng of the VFC requred for kw P A generator s around 0 kvar. Then, the apparent power SA s gen as S A = P A + Q A = + 0 = 7 kva. So the current ratng of VSC s V C = 7 kva I C = 5.7 A. The ampltude of the current s I C pk = 7.9 A. The aerage current s I ag = A = 46.5 A. I Here, the modulaton ndex m a s consdered equal to alue of. The rpple current through the nductor s taken 5%Oerloadng factor due to transent condton ares from 0% to 80% The swtchng frequency of 0 khz s selected for IGBTs of VSCs. The flter nductor s calculated by substtutng the alues of parameters as L an = L bn = L cn = ma * * f * I = mh. The lnk oltage s selected as V V = 677 V. s LRpple The lnk capactor can be estmated by consderng the oltage rpple across t. The alue of the capactor can be determned by the followng equaton: V Rpple cdt c Iag C I ag = 46.5 A, and ω = 4 rad/s for a 50-Hz WECS, the alue of the bus capactor s gen as V Rpple Consderng V Rpple =.54V Iag C V Rpple of % == F VI. SIMULATION, RESULTS AND DISCUSSION Model wth oltage and frequency control s modelled usng MATLAB for lnear unbalanced loads. The results are gen below and we can see dstorton s ery much reduced. A.Smulaton of the Controller Feedng unbalanced LnearLoads On the bass of earler current ratng, the peak-to-peak current rpple consderng 5% of the peak current through the flter nductor can be estmated as I Lrpplepk pk = A =.6595A. By estmatng ths current rpple and the aerage alue of the current, the alue of flter nductors and lnk capactors can be estmated for arous VFC topologes as follows

Internatonal Journal of Scentfc and Research Publcatons, Volume, Issue, March 0 4 Fg.6.Computaton of acte component of reference source current Fg..Wnd generator feedng unbalanced lnear load Fg.

4 Internatonal Journal of Scentfc and Research Publcatons, Volume, Issue, March 0 4 Fg.6.Computaton of acte component of reference source current Fg..Wnd generator feedng unbalanced lnear load Fg..Wnd generator feedng unbalanced lnear load. The unbalance s gen usng breakers. The system frst started at no load,that s frst breaker n open poston. Then at s t s closed and load gen.then at. s unbalance s gen by openng phase at.s. Fg.7.Computaton of reacte component of reference source current and reference current generaton Fg.4.Wnd power generaton The subsystems for acte,reacte power, tm generaton generaton re gen below. Fg.8.Transent waeforms durng applcaton of balanced/unbalanced 0.8 pf laggng load at fxed wnd speed Fg.5. tm generaton Fg.8.demonstrates the performance of the controller for feedng unbalanced lnear loads.at s load s gen and later on at. s one phase of the load are opened usng breakers and the load becomes unbalanced but oltage and current at the generator termnals reman balanced under such worst case of load VII. CONCLUSION The performance of the proposed controller has been demonstrated for an solated wnd energy conerson system.

5 Internatonal Journal of Scentfc and Research Publcatons, Volume, Issue, March 0 5 Smulaton results hae erfed the performance of the controller under unbalanced lnear load. It has been obsered that the proposed controller has been found to regulate the magntude and frequency of the generated oltage constant n solated wnd power applcaton.. [6] J. M. Ramrez and E. Torres M, An electronc load controller for the selfexcted nducton generator, IEEE Trans. Energy Conerson, ol., no., pp , Jun [7] L. A. C. Lopes and R. G. Almeda, Wnd-dren self excted nducton generator wth oltage and frequency regulated by a reduced ratng oltage source nerter, IEEE Trans. Energy Conerson, ol., no., pp , Jun. 006 REFERENCES [] B. Sngh and Gaura Kumar Kasal Sold State Voltage And Frequency Controller For Stan Alone Wnd Power Generatng System, IEEE Trans. On Power Electroncs, ol., no., pp.70 77, May. 008 [] B. Sngh, S. S. Murthy, and S. Gupta, Analyss and desgn of STATCOM based regulator for self excted nducton generator, IEEE Trans. Energy Conerson, ol. 9, no. 4, pp , Dec [] B. Sngh, S. S. Murthy, and S. Gupta, A oltage and frequency controller for self-excted nducton generators, Elect. Power Compon. Syst., ol. 4, pp. 4 57, Feb [4] B. Sngh, S. S. Murthy, and S. Gupta, Transent analyss of self excted nducton generator wth electronc load controller supplyng statc and dynamc loads, IEEE Trans. Ind. Appl., ol. 4, no. 5, pp , Sep [5] B. Sngh, S. S. Murthy, and S. Gupta, Analyss and desgn of electronc load controller for self-excted nducton generators, IEEE Trans. Energy Conerson, ol., no., pp. 85 9, Mar AUTHORS Frst Author Nnu Joy dd BTech. Degree n Electrcal and Electroncs Engneerng at Vswa Jyoth college of Engneerng and Technology. and M. Tech n Power System from Santgts college of Engneerng,Pathamuttom. She currently holds the post of Assstant Professor n thedepartment of Electrcal and Electroncs M.A College of Engneerng, Kothamangalam.Her emal d:joynnujoy@gmal.com Second Author Benny cheran currently holds the post of Professor n the Department of Electrcal and Electroncs M.A College of Engneerng, Kothamangalam. Thrd Author Salce Peter currently holds the post of Professor n the Department of Electrcal and Electroncs M.A College of Engneerng, Kothamangalam.

Comparison of Reference Compensating Current Estimation Techniques for Shunt Active Filter

Comparison of Reference Compensating Current Estimation Techniques for Shunt Active Filter Comparson of Reference Compensatng Current Estmaton Technques for Shunt Acte Flter R.SHANMUGHA SUNDARAM K.J.POORNASEVAN N.DEVARAJAN Department of Electrcal & Electroncs Engneerng Goernment College of Technology