Thailand Experiences in Overvoltage Analysis and Events in Electric Power Transmission System due to Switching and Lightning Surges

Overvoltages analysis in electric transmission system causes by switching and lightning surges and outage events involves modeling and the use of transient program as well as condition of electric operation such as energisation and other system performance, electric generating authority of Thailand (EGAT) and Thai universities have been collecting field data and making case study analysis up to 500 kV systems. Benefits obtained could gain confidence in transmission system outage performance due to insulation failure. In this paper, practical analytical elements of network modeling of power system components suitable to electromagnetic transient program (EMTP) analysis are shown collectively such as for reactive compensators, different line models including frequency dependent line model, etc. Collective information of events and analytical case studies based in Thai power system network has been shown. Data of lines, p.u. overvoltages of different system level, critical points of risks of failure found are identified. The simulation of transient phenomena is mostly required for the design of power apparatus and protective devices, as well as for the insulation coordination improvement. The studies are done to analyze and set up transmission line system models utilized for power system operation and further system expansion.