Lightning back flashover double circuit tripping pattern of 132 kV lines in Malaysia (original) (raw)
Abstract
This paper presents a study on flashover patterns due to double tripping using EMTP software. The simulation was performed on a 132
kV line double circuit for economic installation of transmission line arresters (TLAs). The simulation results were validated with the field data of 132
kV transmission line in Malaysia. A vertically configured double circuit transmission line was modelled and the effects of tower footing resistance, lighting current values, power frequency voltage and the coupling effect of the phase conductors study were taken into account. A good agreement between the simulation and field data was obtained. A specific back flashover phase of the double circuit line can be determined by considering the effects that have been mentioned. Through determination of the tripping pattern, a suitable installation of line arresters and mitigation of line tripping due to back flashover can be achieved.
Highlights
► Simulation using EMTP for lightning-caused flashover pattern of 132 kV double circuit. ► 70% of line outages are due to lightning and significant number is double circuit tripping. ► Determination of parameters that influence flashover pattern was verified using EMTP. ► Parameters are frequency voltage, coupling factor, lightning current and footing resistance. ► Based on the tripping pattern line lightning arrester can be economically installed.
Introduction
Malaysia experiences a high number of thunderstorms, which is 220
days per year and records a flash density of 20
flashes/km/year. The lightning current varies from 3
kA to 200
kA and the mean is 31
kA [1]. According to the statistics, it is estimated that lightning has caused about 70% of the total annual line outages [2]. The types of flashovers which occur when a lightning hits the transmission lines are back flashover and shielding failure. Back flashover occurs when the lightning strikes on a shield wire or tower, where the resultant voltage across the insulator is large enough to cause a flashover from the tower to the line conductors. This voltage depends on the surge characteristics of the tower footing resistance, surge impedances of the shield wire, tower and phase conductors and the lightning magnitude and rise time [3]. Shielding failure occurs when lightning strikes on the phase conductor [4]. Since vast majority of the strokes and flashes terminate on the tower or ground wires, only back flashover is considered in this work [5], [6].
Back flashover pattern studies have been conducted by various researchers. In most of the studies, the tripping patterns due to back flashover are usually considered in a single or double circuit phase conductor. They are grouped into upper, middle and lower phase conductors to determine the lightning performance [7]. However, in this study, a specific flashover according to the phase conductor for both circuits were determined by considering power frequency voltage, coupling effects, footing resistance and lightning current. The patterns of back flashover across each phase for double circuit were investigated to determine the most effective location for the installation of TLAs to eliminate back flashover. The actual line parameters were modelled using EMTP software and the simulations results were compared to the actual site data. The method for determining the pattern of a specific back flashover for 132
kV double circuit transmission line with chosen parameters are summarised in this paper.
Section snippets
Lightning current
A lightning current model proposed by Bruce and Godle was used in the simulation [8]. The proposed lightning current waveform is a double exponential function with a front time of 8
μs and tail time of 50
μs and is given byi0(t)=kI0(e-αt-e-βt)where _I_0 is the peak of lightning current; _i_0(t), the instantaneous lightning current; α, β are wave-head and wave-tail attenuation quotient of lightning current; and k is the waveform correction index.
A lightning waveform of 8/20
μs was used in the
Power frequency voltage
Two separate ac sources are used for double circuit transmission line as illustrated in Fig. 5. Source 1 is the supply for circuit 1 while source 2 is for circuit 2. Both of the sources are synchronised with each other, as shown in Fig. 6, Fig. 7. Table 1 shows the simulation flashover results on a 132
kV double circuit transmission line. The footing resistance of the tower was kept constants at 10
Ω while the angle of the ac sources was varied to investigate the effect on flashover at a specific
Conclusion
An analysis of flashover pattern on a double circuit transmission line with vertical configuration has been successfully performed using EMTP. The results between simulation and the actual field data are within reasonable agreement to each other. Verification of the model in EMTP is able to identify the parameters that influence the flashover pattern. The identified parameters are power frequency voltage, coupling effects, lightning current and footing resistance. Therefore, from the results
Acknowledgments
This work was supported by the Malaysian Government and University of Malaya, Kuala Lumpur under HIR/MOHE research Grant (Grant Code: D000004-16001).
References (12)
- et al.
Insulation coordination associated with distributed generation connected at distribution level
Int J Electr Power Energy Syst
(2011)
- A.H.A. Bakar et al.
Analysis of lightning-caused ferroresonance in capacitor voltage transformer (CVT)
Int J Electr Power Energy Syst
(2011)
- M.Z.A. AbKadir
Application of the insulator coordination gap models and effect of line design to back flashover studies
Int J Electr Power Energy Syst
(2010)
- Nuci CA. A survey on CIGRE and IEEE procedures for the estimation of the lightning performance of overhead transmission...
- Ab Halim Ab Bakar, Mohd Ridzal Othman, Hairussaleh Osman. Economic positioning of line lightning arresters based on...
- M.R.B. Tavakoli et al.
Discrete-event simulation of the shielding failure of the arrester protected overhead-lines to evaluate risk of flashover
Int J Electr Power Energy Syst
(2008)
There are more references available in the full text version of this article.
Cited by (27)
2019, Measurement: Journal of the International Measurement Confederation
Hence, the instantaneous power frequency voltage has a significant contribution to the overvoltage induced due to back flashover. The simulated results have also been validated based on the previous research, in which the tripping characteristics are comparable in terms of power frequency voltage variation [15]. The effectiveness of surge arrester (SA) configurations to improve the line flashover performance is discussed in the following section.
View all citing articles on Scopus
Copyright © 2012 Elsevier Ltd. All rights reserved.