Effectiveness analysis of primary and secondary protective measures for 500 kV substation switch transient field

Measurement, monitoring, and other secondary equipment that devolve to switch field are directly exposed to a complex electromagnetic environment and are thus severely disrupted. This study aimed to reduce a fast transient overvoltage and secondary cable terminal interference voltage. Simulation and analysis involved the substation EMTP calculation model of the conducted interference of the primary and secondary systems for the fast transient overvoltage caused by the switching operation and secondary cable in the conducted interference protection measures. Furthermore, various protective measures for the isolating-switch switching no-load transformer were analyzed. Results showed that parallel resistance added to the isolating switch at the primary side, whereas filter capacitance added to the secondary side, both measures significantly reduced overvoltage and interference voltage, and can be easily applied in practical engineering.