Improvement of Power Quality in a Grid Connected Wind Energy Conversion System by STATCOM

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STATCOM M V S Kartheek 1 N.Siva Nagendra 2 Baipalli Vasulu 3 1,2,3 Assistant Prfessr, Department f EEE, BVC Engineering Cllege, Odalarevu, Andhra Pradesh, India. T Cite this Article M V S Kartheek, N.

1 Available nline at: Internatinal Jurnal fr Mdern Trends in Science and Technlgy ISSN: :: Vlume: 04, Issue N: 02, February 2018 Imprvement f Pwer Quality in a Grid Cnnected Wind Energy Cnversin System by STATCOM M V S Kartheek 1 N.Siva Nagendra 2 Baipalli Vasulu 3 1,2,3 Assistant Prfessr, Department f EEE, BVC Engineering Cllege, Odalarevu, Andhra Pradesh, India. T Cite this Article M V S Kartheek, N.Siva Nagendra and Baipalli Vasulu, Imprvement f Pwer Quality in a Grid Cnnected Wind Energy, Internatinal Jurnal fr Mdern Trends in Science and Technlgy, Vl. 04, Issue 02, February 2018, pp ABSTRACT The perating perfrmance f wind electric generatrs has cnsiderable stress n the quality f electric pwer and reliability in the perfrmance pwer systems [1]. Pwer quality issues such as vltage dip, harmnic distrtin and reliability prblems are main cnsideratins in this wrk. The vltage distrtin & reactive pwer issues are als cnsidered. The pwerful MAT LAB tl is used t analyse the pwer quality issues and ther reliability prblems in this paper and als the perfrmance f inductin generatr cnnected with grid is als analyzed fr pwer quality prblems. The cmpensatr is designed t inject reactive pwer t vercme pwer quality prblems and als fr better grid peratin. There is a cntinuus variatin in terminal vltage because f the varying wind speed. The additin f STATCOM int the system supprts t maintain the active pwer, reactive pwer and terminal vltage as cnstant and STATCOM fr steady state and dynamic impact study is presented, and the mdel is validated by cmparing with the actual field data.the wind turbine generatrs have pwer electrnic based cnverters can be effectively utilized fr efficient cntrl f pwer, but they generate harmnics. The mdified STATCOM as shunt active filter which is used fr reducing system harmnics and t imprve the system perfrmance. The STATCOM mdel is implemented using PIC cntrller KEYWORDS: SVC, STATCOM, FACTS, GTO, PV, VQ, TC. Cpyright 2018 Internatinal Jurnal fr Mdern Trends in Science and Technlgy All rights reserved. I. INTRODUCTION The number f renewable energy surces and requires a new technique fr the peratin f electric pwer systems, in rder t reach the pwer quality nrms. Nw a day s wind mills are cnnected t the pwer system t meet the cmmnly used device fr flicker reductin is the STATIC V AR Cmpensatr [SVC] [1]. On cmparing STATCOM with SVC, the STATCOM has sme advantages, such as better perfrmance, quick respnse, smaller in size, less cst, and capable f satisfying bth active and reactive pwer requirements. The prpsed cmpensatr cnsisting f a vltage surce cnverter, (VSI) uses advanced pwer semicnductr switches t prvide flexibility in vltage cntrl fr pwer quality imprvement[l]. This methd is suitable fr the applicatins with frequently fluctuating lads and pwer flw. By using high frequency switching PWM, the high speed switching cnverter will generate smth current with lw harmnic cntent. In this thesis, a inductin generatr is mdelled using MATLAB and flicker generatin f 11 Internatinal Jurnal fr Mdern Trends in Science and Technlgy

2 grid cnnected wind turbines fed inductin generatrs is analyzed fr varying lad cnditins. The high speed switching pwer cnverters, which are used t extract maximum pwer at the available speed, are cnnected between the inductin generatr and grid. Harmnics due t the varying lad cnditins are reduced by designing cmpensatr as a shunt active filter. Nrmally, the lw-cst mechanical switched cap [MSC] banks and transfrmer tap changers [TCs] are used t address these prblems related t grid stability and pwer quality. Even thugh these devices are very much helpful t imprve the pwer factr and steady-state vltage regulatin, the majr pwer quality Issues, such as pwer fluctuatins, vltage flicker and harmnics intrductin cannt be reduced effectively by them because these devices are nt having fast respnse. S a fast respnse shunt VAR cmpensatr is needed t slve these issues mre effectively, as has been pinted ut in many literatures. The static synchrnus cmpensatr [STATCOM] IS suitable fr this applicatin, because it prvides many advantages, in particular the fast respnse time and superir vltage supprt capability with its nature f vltage surce. The recent innvatins ill high-pwer, high speed semicnductr switch cnverter tplgies, and efficient digital cntrl technlgy, fast respnse ST ATCOM with lw cst is emerging, which is prmising t help integrate wind energy int the grid t achieve a mre cst-effective and reliable renewable wind energy. II.POWER QUALITY ISSUES When a varying lad is cnnected t the grid the fundamental sinusidal wavefrm f current flwing thrugh system will change. This prblem will cause nn-sinusidal vltage drp acrss the netwrk element cnnected t the grid that leads t distrting the wavefrm prpagatin thrughut the grid t buses remte frm the surce. III.VOLTAGE FLICKER The Vltage flicker in the grid describes dynamic variatins in the netwrk terminal vltage. The switching actin f heavy inductive lads and ther large fluctuating lads like arc furnaces, rck crushing machinery sawmills are the majr reasn fr vltage flickering. Hwever, it is f cnsiderable significance fr wind farms cnnected with the netwrk which are, (i) Frequent switching actins(on/off) (ii) Subjected t cntinuus input pwer variatins Flicker generatin due t switching peratins arises frm the starting and stpping f the wind turbines. Vltage stability prblems and cllapse ccur n grid that are nt able t meet the demand fr reactive pwer, are heavily laded and/r faulted. Interruptin ccurs in the netwrk when an interrupts the circuit serving a particular custmer. IV. HARMONICS A wind electric generatr directly cnnected t the grid withut a fast acting pwer electrnic switching cnverter is nt expected t distrt the fundamental wavefrm. The additin f Pwer electrnics switches used fr sft start and stp may generate high rder current harmnics fr shrt duratin but their magnitudes are small. The variable speed wind turbines using pwer electrnic cnverters fr these reasns shuld be assessed against specified r calculated limits cntrllers are prperly cntrlled. The FACTS cntrllers are mainly used t nrmalize terminal vltage and cntrl pwer flw thrugh the transmissin lines. In STATCOM by cnnecting pwer electrnic switches and switching them at exact angles within each 50 Hz cycle an accurate sinusidal wavefrm is develped. If the generated vltage in this methd is higher than terminal vltage the cmpensatr will supply reactive pwer as that f synchrnus cndenser and imprve the vltage level and cnversely if lwer it will remve reactive pwer frm the system. The prpsed STATCOM has the ptential t maintain its reactive current at lw vltage since it has cnstant current characteristics while a thyristr SVC is cnstant impedance. The STATCOM prpsed here can prvide fast capacitive and inductive fr harmnics. Nw a day s wind turbine designs use transistr-based cnverters, which are perated at very high switching frequencies abve 3 khz and their effect n the vltage wavefrm is usually negligible. V.POWER QUALITY IMPROVEMENT The FACTS cntrllers are mainly based n pwer electrnic cntrllers that enhance the transferring ability f the line. The pwer electrnic cntrllers are fast in respnse and increase the stability limits f the pwer transmissin systems when their assciated cntrllers are prperly cntrlled. The FACTS cntrllers are mainly used t 12 Internatinal Jurnal fr Mdern Trends in Science and Technlgy

3 nrmalize terminal vltage and cntrl pwer flw thrugh the transmissin lines. In STATCOM by cnnecting pwer electrnic switches and switching them at exact angles within each 50 Hz cycle an accurate sinusidal wavefrm is develped. If the generated vltage in this methd is higher than terminal vltage the cmpensatr will supply reactive pwer as that f synchrnus cndenser and imprve the vltage level and cnversely if lwer it will remve reactive pwer frm the system. The prpsed STATCOM has the ptential t maintain its reactive current at lw vltage since it has cnstant current characteristics while a thyristr SVC is cnstant impedance. The STATCOM prpsed here can prvide fast capacitive and inductive cmpensatin. STATCOM has the ability t cntrl its utput current independent f the netwrk vltage. Figure 1. Vltage Fluctuatin Mitigatin with STATCOM Figure 1 shws the lcatin f STATCOM t reduce vltage sag. Generally STATCOM is effective shunt cmpensatr used t maintain vltage prfile cnstant. Here the cmpensatr is cnnected between surce and pwer transfrmer. The first use f wind pwer was t sail ships in the Nile sme 5000 years ag. The Eurpeans used it t grind grains and pump water in the 1700s and 1800s. The first windmill t generate electricity in the rural U.S.A. was installed in Tday, large wind pwer plants are cmpeting with electric utilities in supplying ecnmical clean pwer in many parts f the wrld The average turbine size f the wind installatins has been 300 kw until the recent past. The newer machines f 500 t 1,000 kw capacities have been develped and are being installed. Prttypes f a few MW wind turbines are under test peratins in several cuntries, including the U.S.A. It is a cnceptual layut f mdern multi mega watt wind twer suitable fr utility scale applicatins Majr factrs that have accelerated the wind-pwer technlgy develpment are as fllws High-strength fiber cmpsites fr cnstructing large lw-cst blades. Falling prices f the pwer electrnics. Variable-speed peratin f electrical Generatrs t capture maximum energy. Imprved plant peratin, pushing the availability up t 95 percent. Ecnmy f scale, as the turbines and plants are getting larger in size. Accumulated field experience [the learning curve effect imprving the capacity factr. A. Cnventinal Circuit Drawbacks Mre Vltage fluctuatin Reactive pwer required fr magnetizatin Pr pwer factr Variable terminal vltage Pr pwer quality B. C. B. Advantages Imprve the vltage wavefrm frm distrtin Imprve the pwer quality Reactive pwer cmpensatin Maintain cnstant utput vltage Figure 2 represents the blck diagram f static cmpensatr with nn linear lad. Nrmally inductin generatr IS used in wind energy generating units. VI. WIND POWER C. Applicatins Pwer cmpensatin in Grid Vltage stability imprvement in Grid Pwer and vltage Cntrl in Grid system D. Simulatin 13 Internatinal Jurnal fr Mdern Trends in Science and Technlgy

Fig. 6 shws the line mdel with additinal lad. It cnsists surce, transfrmer and main lad.

2 sec additinal lad is cnnected t increase the lad impedance.

Fig 3 shws the surce side vltage and Fig 4 and 5 shws the peak and RMS lad vltage. Figure6.

Surce side vltage Figure4. Lad vltage with sag cnditins Figure5.

mdel. It cnsists surce, transfrmer, ST ACOM mdel and main lad.

Vltage sag ccurs due t lad variatin. At t=0.25 sec the STATCOM IS cnnected t the system.

4 Fig. 6 shws the line mdel with additinal lad. It cnsists surce, transfrmer and main lad. Initially lad ne is cnnected t the surce. At t =0.2 sec additinal lad is cnnected t increase the lad impedance. Vltage sag ccur due t lad variatin. Fig 3 shws the surce side vltage and Fig 4 and 5 shws the peak and RMS lad vltage. Figure6. Circuit diagram with STATCOM mdel Figure3. Surce side vltage Figure 7.Surce side vltage Figure4. Lad vltage with sag cnditins Figure5. RMS Lad vltage with sag cnditins Fig 6 shws the line mdel with additinal lad and STATCOM mdel. It cnsists surce, transfrmer, ST ACOM mdel and main lad. Initially lad ne is cnnected t the surce. At t =0.2 sec additinal lad IS cnnected t increase the lad impedance. Vltage sag ccurs due t lad variatin. At t=0.25 sec the STATCOM IS cnnected t the system. S that vltage sag is cmpensated Fig 6 shws the STATCOM mdel. Fig 7 shws the surce side vltage and Fig 8 and 9 shws the peak and RMS lad vltage. Figure 8.Lad vltage with sag cnditins Figure 9.RMS Lad vltage with sag cnditins 14 Internatinal Jurnal fr Mdern Trends in Science and Technlgy

lad IS cnnected t increase the lad impedance.

3 sec the STATCOM is cnnected t the system.

Fig 15 and 16 shws the wind side and surce side vltage and Fig 17 and 18

line mdel with wind and surce cmbinatin Fig 10 shws the line mdel with

It cnsists wind energy system, surce, transfrmer and main lad.

Fig 11 shws the surce side vltage and Fig 12 and 13 shws the peak and RMS

Generatr side vltage Figure l1.generatr side vltage Figure 16.

5 lad IS cnnected t increase the lad impedance. Vltage sag ccurs due t lad variatin. At t=0.3 sec the STATCOM is cnnected t the system. s that vltage sag is cmpensated Fig 16 shws the STATCOM mdel. Fig 15 and 16 shws the wind side and surce side vltage and Fig 17 and 18 shws the peak and RMS lad vltage. Figure 10.line mdel with wind and surce cmbinatin Fig 10 shws the line mdel with additinal lad. It cnsists wind energy system, surce, transfrmer and main lad. Initially lad ne is cnnected t the surce. At t =0.2 sec additinal lad is cnnected t increase the lad impedance. Vltage sag ccur due t lad variatin. Fig 11 shws the surce side vltage and Fig 12 and 13 shws the peak and RMS lad vltage Figure 14.STATCOM circuit diagram Figure 15.Generatr side vltage Figure l1.generatr side vltage Figure 16.Surce side vltage Figure 12.Lad vltage with sag cnditins Figure 17. Lad vltage with sag cnditins Figure 13.RMS Lad vltage with sag cnditins Fig 14 shws the line mdel with additinal lad. It cnsists wind energy system, surce, transfrmer, STATCOM mdel and main lad. Initially lad ne is cnnected t the surce. At t =0.25 sec additinal 15 Internatinal Jurnal fr Mdern Trends in Science and Technlgy

6 Figure 18.RMS Lad vltage with sag cnditin VII. HARD WARE IMPLEMENTATION BLOCK DIAGRAM Figure 19.Hardware implementatin blck diagram VIII.CONCLUSION This research presents the STATCOM based cntrl scheme fr pwer quality imprvement in grid cnnected wind generating system and with nnlinear lad. The pwer quality issues and its Cnsequences n the cnsumer and electric utility are presented. The peratin f the STATCOM in MATLAB/SIMULINK fr maintaining the pwer quality is simulated. It has the capability t cancel ut the harmnic parts f the lad current. It maintains the surce vltage and current in phase and supprts the reactive pwer demand fr the wind generatr and lad at PCC in the grid system, thus it gives an pprtunity t enhance the utilizatin factr f the transmissin line. The integrated wind generatin and STATCOM have the utstanding perfrmance. Thus the prpsed scheme in the grid cnnected system fulfills the pwer quality nrms as per the IEC standard In additin, since the STATCOM suppresses the vltage fluctuatin, it is apparent that, cmpared t the case withut STATCOM, the switching times f bth main transfrmers and lad transfrmers t address the vltage fluctuatin issue in the system shall be significantly reduced. Therefre, the maintenance and replacement cst f and wind turbines can be lwered, and the pwer quality issues related t the switching f can als be lessened. REFERENCES [1]. Sharad W.Mhd and Mhan V.Anware "A STATCOM cntrl scheme fr grid cnnected wind energy system fr pwer quality Imprvement,"IEEE systems jurnal,vl.4,n.3 Sep 2010 [2]. Han.C, A. Q. Huang, M. Baran, S. Bhattacharya, and W. Litzenberger, "ST ATCOM impact study n the integratin f a large wind farm int a weak lp pwer system," IEEE Trans. Energy Cnv., vl. 23, n. 1, pp , Mar [3]. Mhd.S.W and M. V. Aware, "Pwer quality issues & it's mitigatin technique in wind energy cnversin," in Prc. f IEEE Int. Cnf. Quality Pwer & Harmnic, Wllngng, Australia, [4]. Varun Singhal." Imprved cntrl f Three phase active filters using Genetic Algrithms" th Internatinal Cnference n Pwer Electrnics and Drive Systems, 11/2007. [5]. A.R.Mghabdmj." Optimal sizing f Hybrid Pwersystem using genetic Algrithm. Internatinal Cnference n Future Pwer Systems, [6]. Liu Lianguang."Simulatin and Analysis f vltage sag mitigatin using active series vltage injectin, Pwer Cnference 2000, lnternatinal Cnference f Pwer system Technlgy Prceedings, [7]. H.R. Najafi. "Transient Stability Evaluatin f Wind Farms Implemented with Inductin Generatrs", Internatinal Universities Pwer Engineering Cnference [8]. Mhd.S.W and M. V. Aware, "Grid pwer quality with variable speed wind energy cnversin," in Prc. IEEE Int. Cnf Pwer Electrnic Drives and Energy System [PEDES], Delhi, Dec [9]. Arulampalam.A, M.Barnes & N.Jenkins, Pwer quality and stability imprvement f a wind farm using STATCOM, Prc. IEE Generatin, Transmissin & Distributin, Vl. 153, N.6, 2006, [10]. HeieLS, "Grid Integratin f Wind Energy Cnversins. Hbken", NJ: Wiley, 2007, pp Internatinal Jurnal fr Mdern Trends in Science and Technlgy

Facilities Study Report

Facilities Study Report Wellhead Pwer Cltn, LLC Facilities Study Reprt Revised May 15, 2014 Prepared by: Edgar Ramirez Rger Salas, P.E. Distributin Field Engineering Apprved by: Rger Salas Distributin Field Engineering Manager