Time and frequency characterisation of transients because of switching in 400 kv air-insulated substations: bus bar currents

Switching operations of devices such as circuit breakers and disconnect switches within high voltage substations generate transient electromagnetic fields. The transient fields may impair normal operation of the equipment used for measurement, communication, protection and control purposes. The magnitude and characteristics of the transient fields depend on the wave shape and magnitude of transient currents propagating on the substation bus bars. This study discusses modelling of 400 kV air-insulated substation with the aim of characterising the transient currents both in the time and frequency domains. This is achieved by making use of the electromagnetic transient program. The effects of switching configurations and substation layout on the transient currents are investigated. The magnitude and dominant frequency components of the transient current at different positions are also identified.