Experimental Study of Fast Transient Currents in Gas Insulated Substation

The increasing demand in transmitting electrical energy at very high voltages with low transmission losses and improved efficiency has led to the development of compact metal enclosed gas insulated substation. There are various advantages of gas insulated substations over conventional substations yet there are a few problems associated with the switching operation in gas insulated substation. The fast transient voltages arising due to the switching operation of disconnectors or circuit breakers may impair the service reliability. The fast transient currents are associated with these fast transient voltages. The main aim of this paper is to characterize the fast transient currents generated due to the switching operations in a gas insulated substation. The dominant frequency content has been identified for different rise times of the fast transient currents and the percentage attenuation in amplitude is determined at different distances from the source. The variation in the peak value of current with distance from the source is also analysed. The experimental work is carried out on 145 kV gas insulated substation models of different configurations and comparison of the results for different case studies are reported.