Improved EHV line switching surge control via controlled switching technique

The limitation of switching overvoltage during EHV transmission line re/energization can be achieved traditionally through usage of circuit breakers equipped with pre-insertion resistors as well as the use of MOV surge arresters at both line ends and along the line. A recent and novel technique to reduce the switching transients is controlled switching. In this paper the results of comparative analysis considering two alternative; pre-insertion resistors application and controlled switching technique, to reduce switching surge overvoltage during EHV transmission line re/energization with probability of trapped charge in lines are presented. The simulations are made with EMTP for line feeders of an actual under-construction 400 kV switching substation in Iran Transmission Power Network. The simulation results prove a promising performance of controlled switching in comparing with traditional methods to limit switching over-voltages.