Abstract Field distribution of electromagnetic wave propagating in a gas insulated switchgear (GIS) can be distorted locally at the discontinuous/abrupt positions like elbows, spacers and bushings. The effect of such distortion is usually regarded as a lumped circuit element inserted into the transmission line model. For L-type elbow of GIS pipe, both π-type and T-type equivalent circuits consisting of compensation capacitance and compensation inductance are investigated in this paper. Based on the two-port network parameter obtained by electromagnetic simulation of the L-shaped pipe, the formulae of both the compensation capacitance and inductance are derived by using transmission line theory. For a 1100kV GIS dimensions, the capacitance is about 15~32pF and the inductance is about 0.1~0.2μH when the T-type circuit adopted, and the capacitance is about 15~40pF and the inductance is about 0.08~0.23μH when the π-type circuit adopted. Both the capacitance and the inductance are changing with the frequency. A circuit including a terminal load on one end of the L-shape pipe and a pulse voltage source on the other end is established to compare the difference between the two cases: with and without the equivalent circuit inserted. It is shown that, the equivalent circuit has obvious effect on the load voltage waveform when the load matches badly with the pipe, but has few influence when the two match with each other well.
Cao Shuyun,Jiao Chongqing. Influence of L-Shape Part of GIS Enclosure on Electromagnetic Propagation Characteristics and Equivalent Circuit Model[J]. Electrical Engineering, 2016, 17(11): 6-12.
2016, Vol. 17 
