Influence of Substation's Elements on Electromagnetic Transient Occurrences Caused by Disconnector Switching
Abstract This article presents the results of investigating switching overvoltages caused by the operation of disconnectors in air-insulated substations rated at 220 kV. Measurements of switching overvoltages were performed in air-insulated substations at the Hydro Power Plant Grabovica on the River Neretva and at the Thermo Power Plant Kakanj. These power plants are of great importance to the operation of the electric power system in Bosnia and Herzegovina. Operation of air disconnectors was investigated in order to determine the switching overvoltages' shapes and levels in primary and secondary circuits, which could cause malfunctioning of signaling devices or burning of protection relays' supply units. Results of computer simulations using an electromagnetic transients program are presented. Comparison of measured and calculated overvoltage values confirms their concordance. These comparisons proved computer calculation to be useful for investigating transient overvoltages due to disconnector switching. Furthermore, experimental and computing investigations on the 220-kV switchyard of the Hydro Power Plant Grabovica demonstrate an influence of substation's elements on the waveform of switching overvoltages.