Properties of Leakage Current on 20 kv Ceramic Insulators and Computer Simulation Based on Electrical Equivalent Circuit

Transcription

1 Proceedings of he World Congress on Engineering 2 Vol II WCE 2, June 3 - July 2, 2, London, U.K. Properies of Leakage Curren on 2 kv Ceraic Insulaors and Copuer Siulaion Based on Elecrical Equivalen Circui Suwarno, Meber IENG and diya Pradana bsrac During operaion, oudoor insulaors ay severe a cerain degree of polluion which ay reduce heir perforances such as surface resisance and flash over volages. Under hese condiions a large leakage curren () ay flow on he surface and degradaion ay ake place. Leakage curren on 2 kv pos-pin ceraic insulaors were invesigaed under several arificial polluion levels. n C volage up o 6 kv was applied o he insulaor saples under clean and sal fog condiions. The wavefors were easured using a digial sorage oscilloscope and he digial daa was ransferred o a personal copuer for furher analysis. The experienal resuls indicaed ha in general he wavefors were disored fro sinusoidal. The disorion srongly correlaed wih he polluion levels, fog condiions and applied volage. paricular condiion, asyerical behavior of he wavefor beween posiive and negaive half cycles was observed. In order o ge a beer undersanding of he insulaor behaviors, elecrical circui odel is proposed. The insulaor is represened by an elecrical circui ha produces wavefor when a sinusoidal volage is applied. In general, elecrical circui consiss of capacior(s), nonlinear resisor(s), and arc odel(s). Using he proposed elecrical circui, copuer siulaion of he leakage curren was done by using TP/EMTP. The siulaed leakage curren wavefors were copared o hose obained fro experien. The siilariy of he siulaed and experienal leakage currens was assessed by using heir agniude, doinan coponens, oal disorion (THD) and asyery of he. The resuls showed good siilariy beween easured and siulaed leakage curren wavefors which indicaed he validiy of he proposed odel. Ceraic insulaors are widely used in power syse since long ie ago. presen ie he insulaors are sill widely being used. Ceraic insulaor has good echanical and elecrical properies and less expensive. s oudoor insulaor i ay severe a cerain degree of polluion and oher environenal facors which ay reduce heir surface resisance. The reducion of surface resisance ay enhance he leakage curren o flow on he surface[]. Leakage curren () wih large agniude and conains coponens flow on he surface for long period ay cause degradaion of he insulaor surface[2-4]. In long er he degradaion ay lead o he flashover of he insulaors and i is necessary o diagnosed [5]. Therefore, invesigaion on he leakage curren on he ceraic insulaors under pollued condiion is iporan. The flashover of he insulaor is also necessary o be invesigaed. This paper repors he experienal resuls on he invesigaion on leakage curren, and flash over characerisics of ceraic insulaors. II. EXPERIMENT ND TYPICL LEKGE CURRENT WVEFORM The saples used in his experie were ceraic 2 kv insulaors which are widely used in Indonesian power syse as shown in figure. es haber ade fro aluiniu panel wih diension of 9 x 9 x 2 3 was used o siulae polluion exposed o he saples. The fron opening of he es chaber was ade fro acrylic o faciliae he observaion of arcing on he saple surface. Index Ters Oudoor insulaor, leakage curren, elecrical equivalen circui, copuer siulaion. I. INTRODUCTION Due o large deand on elecric power, he elecric power generaion, ransission and disribuion in he world has been seadily increased. For ransiing and disribuing he elecric power, insulaors is one of he os iporan pars. Oudoor insulaor are coonly used in an elecric power syse o isolae aong live pars and beween live par and ground and as echanical proecor. The insulaors are widely used a subsaions, ransission as well as disribuion neworks. uhors are wih he School of Elecrical Engineering and Inforaics, Bandung Insiue of echnology, Bandung 432, INDONESI. (e-ail: suwarno@ieee.org). Fig.. 2 kv insulaor saple C high volage wih frequency of 5 Hz was applied o he insulaors. The leakage curren flowed on he insulaor surface was easured by easuring he volage across a series resisance using a Digial Oscilloscope TDS 22 wih digiizer of 8 bi, bandwidh of MHz, and he axiu ISBN: ISSN: (Prin); ISSN: (Online) WCE 2

2 Proceedings of he World Congress on Engineering 2 Vol II WCE 2, June 3 - July 2, 2, London, U.K. sapling rae of GS/s. The easureen syse was able o record he wavefors of leakage currens. The digial daa was ransferred o a personal copuer rough a GPIB for furher analysis. Haronic conen of was analyzed using FFT (Fas Fourier Transfor). Figure 2 shows ypical leakage curren wavefor and s coponens of clean insulaor under clean fog a 6 kv. Figure 2 clearly shows ha he wavefor is disored fro is sinusoidal for. The disorion was caused by he non lineariy volage-curren behavior of he insulaor surface and possible appearance of surface discharges. The disored leakage curren wavefor conained s coponens wih frequency of higher han 5 Hz as shown in figure. The doinan s are 3 rd (5 Hz), 5 h (25 Hz) and 7 h (35 Hz) assessed using he coparison in apliude, doinan s and he oal disorion wih he wavefor obained fro experien. Fig. 3 general equivalen circui odel of insulaor B. Leakage curren for clean insulaor under clean fog Fig. 4 ypical siulaed wavefors for clean saple under clean fog a applied volages of 2 kv, 4 kv and 6 kv Fig 2 Typical leakage curren wavefor and coponens of clean insulaor under clean fog a applied volage of 6 kv III. EQUIVLENT CIRCUIT MODEL ND SIMULTION OF LEKGE CURRENT. Equivalen circui of insulaor The general equivalen circui odel for insulaor is shown in figure 3[6]. I consiss of capacior(s), nonlinear resisor(s), and arcing circui(s). The capacior and nonlinear resisor conneced in parallel, while he arcing circui conneced series wih he nonlinear resisor. The 2 diodes were inroduced o siulae he asyerical behavior of posiive and negaive half cycle leakage curren wavefors. By using he equivalen circui leakage curren wavefors were siulaed using TP progra. Validaion of he proposed equivalen circui odel and is paraeers is done by analyzing and coparing experienal resuls and he siulaion resuls. Validiy of he siulaed resuls were Leakage Curren (4kV) Leakage Curren (6kV) Fig. 5 Typical experienal wavefors for clean saple under clean fog a applied volages of 4 kv and 6 kv ISBN: ISSN: (Prin); ISSN: (Online) WCE 2

3 Proceedings of he World Congress on Engineering 2 Vol II WCE 2, June 3 - July 2, 2, London, U.K. Fig. 4 shows siulaed leakage curren wavefors for clean saple under clean fog a applied volages of 4 and 6 kv. The resuls are siilar wih wavefors obained fro experien as shown in figure 5. The siilariy of he siulaed and experienal wavefors are indicaed by heir apliude, doinan s, oal disorion (THD) and syery. They are presened in able. In general agniude and THD increased wih applied volage. low volage doinan was 5 h while under higher volage 3 rd and 7 h s also appeared. ll wavefors are syerical. Table Coparison beween easured and siulaed wavefors for clean saple under clean fog 4 kv - pliude of -Doinan negaive syery 6 kv - pliude of negaive syery Measured % % Siulaed % % C. Leakage curren for kaolin-sal pollued insulaor wih conduciviy of 3.6 S under clean fog 2 kv, 4 kv and 6 kv Fig. 6 shows siulaed leakage curren wavefors for kaolin-sal pollued saple wih conduciviy of 3.6 S under clean fog a applied volages of 2, 4 and 6 kv. The resuls are siilar wih wavefors obained fro experien as shown in figure 7. The coparison of he siulaed and experienal wavefors in er of apliude, doinan s, oal disorion (THD) and syery are shown in able 2. In general agniude and THD increased wih applied volage. applied volage of 2 kv he wavefor was slighly disored fro sinusoidal, he doinan coponen was 5 h. The wavefor is syerical beween posiive and negaive half cycles. However, when applied volage was increased fro 2 kv o 4 kv, he agniude increased fr4o.3 o 2. The 2 nd, 3 rd and 7 h coponens becae doinan. The wavefor was asyerical. The appearance of 2 nd s indicaed he asyerical behavior. Siilar resuls were observed under applied volage of 6 kv. In general, leakage curren agniude, he wavefor disorion and THD increased wih applied volage Leakage Curren (2kV) 3 Leakage Curren (4kV) Leakage Curren (6kV) Fig. 6 Typical siulaed wavefors for kaolin-sal pollued insulaor of 3.6 S in clean fog a applied volage of Fig. 7 Typical experienal wavefors for kaolin-sal pollued insulaor wih conduciviy of 3.6 S in clean fog a applied volage of 2 kv, 4 kv and 6 kv ISBN: ISSN: (Prin); ISSN: (Online) WCE 2

4 Proceedings of he World Congress on Engineering 2 Vol II WCE 2, June 3 - July 2, 2, London, U.K. Table 2 Coparison beween easured and siulaed wavefors for kaolin-sal pollued saple under clean fog 2 kv - pliude of negaive syery 4 kv - pliude of negaive syery 6 kv - pliude of negaive syery Measured % - 2-5, 3, 7, % - 3-5, 3, 7, % Siulaed % - 2-5, 3, 7, % - 3-5, 3, 7, % Fig. 8 shows ypical siulaed leakage curren wavefors for kaolin- pollued saple under sal fog wih conduciviy of 3.6 S a applied volages of 2, 4 and 6 kv. Figure 8 shows ha under applied volage of 2 kv he siulaed wavefors is syerical wih apliude of.4. Under applied volage of 4 and 6 kv he siulaed becoes unsyerical wih apliude of.83 and.5. The siulaed wavefors shown in figure 8 are siilar wih wavefors obained fro experien as shown in figure 9. The coparison of he siulaed and experienal wavefors in er of apliude, doinan s, oal disorion (THD) and syerical behavior are shown in able 3. s indicaed by able 3, in general agniude and THD increased wih applied volage. applied volage of 2 kv he wavefor was disored fro sinusoidal, he doinan coponen was 3 rd, 5 h and 7 h. However, when applied volage was increased o 4 kv, he agniude and THD increased, he wavefor becae unsyerical and ore disored. The doinan coponens were he 2 nd, 3 rd, 5 h and 7 h. Siilar behavior was observed under 6 kv. agniude and THD increased wih applied volage. D. Leakage curren for kaolin-sal pollued insulaor under sal fog wih conduciviy of 3.6 S.5 [] [s] (file 2kv-r2.pl4; x-var ) c:xx6-xx233. [] [s] (file 4kv-r.pl4; x-var ) c:xx8-xx233 Fig. 8 Siulaed wavefors for kaolin pollued saple under sal fog a 3.6 S and applied volage of 2 kv, 4 kv and 6 kv Fig. 9 Experienal wavefors for kaolin pollued saple under sal fog a 3.6 S and applied volage of 2 kv, 4 kv and 6 kv ISBN: ISSN: (Prin); ISSN: (Online) WCE 2

5 Proceedings of he World Congress on Engineering 2 Vol II WCE 2, June 3 - July 2, 2, London, U.K. Table 3 Coparison beween easured and siulaed wavefors for kaolin- pollued saple under sal fog 2 kv - pliude of negaive syery 4 kv - pliude of negaive syery 6 kv - pliude of negaive syery Measured % ,2, 3, 7-8.2% -.5-5, 2, 3, % Siulaed % , 3, 7-8.6% -.5-5, 3, % REFERENCES [] Siderakis, K, D goris, P Elefheria, and E Thalassinakis. "Invesigaion of Leakage Curren on High Volage Insulaors-Field Measurens." WSES Transacion on Circuis and Syse, 24: [2] Suda, T., Frequency Characerisics of Leakage Curren Wavefors of a Sring of Suspension Insulaors. IEEE Transacions on Power Delivery, Vol. 2, No., 25, pp [3] Suwarno, J. Parhusip, Effecs of Huidiy and Fog Conduciviy on he Leakage Curren Wavefors of Ceraics for Oudoor Insulaors, WSES Trans. On Syses, Vol. 9, Issue 4, 2, pp [4] H El Hag, S.H. Jayara, E.. Cherney, Fundaenal and low Freq. coponens of as a diagnosic Tool o Sudy ging of RTV and HTV SIR in Sal-Fog, IEEE Trans. on Dielecrics and Elecrical Insulaion, Vol., No., 23, pp , Feb. 23. [5] Suwarno, Leakage Curren on oudoor Insulaors under ropical Condiions, In Syp. Elecrical Insul. Mas. 23, Hieji, Japan, Noveber 23 pp.-4 [6] Suwarno, Fari Praoosiwi, Elecrical Equivalen Circui of Ceraic Insulaors wih RTV Silicone Rubber Coaing and Copuer Siulaion of Leakage Currens, WSES Trans. on Circuis and Syses, Vol 8, No. 4, 29, pp IV. CONCLUSIONS Leakage curren on 2 kv pos-pin ceraic insulaors were invesigaed. The experienal resuls indicaed ha in general he wavefors were disored fro sinusoidal. In order o undersand beer he behavior of he insulaor, an elecrical circui odel is proposed. The elecrical circui consiss of capacior(s), nonlinear resisor(s), and arc odel(s). By uilizing he proposed elecrical circui, copuer siulaion of he leakage curren was done using TP/EMTP. The siulaed leakage curren wavefors were copared o hose obained fro experien. The siilariy of he siulaed and experienal leakage currens was indicaed by heir agniude, doinan coponens, oal disorion (THD) and asyery of he. The siulaion resuls showed good siilariy beween leakage curren wavefors obained fro experien and siulaion indicaed he validiy of he proposed odel. ISBN: ISSN: (Prin); ISSN: (Online) WCE 2