The research on lumped parameter equivalent circuit of transmission line

Based on the frequency characteristics analysis, the selection criterion of lumped parameters circuits are presented in this paper. Firstly the Γ section equivalent circuit is introduced as the equivalent of transmission line and its validity is proved. With other lumped parameters circuits, their frequency characteristics are analyzed and compared with the distributed parameters circuit. From characteristic analysis, we estimate the effective frequency band which the lumped parameters circuit can be taken as the equivalent of transmission line. Considering the width of effective frequency and complex degree of model equation, the selection method for application is proposed. The research results showed that π section has the best approximation and Γ section has the simplest model equation. The proper application of selection method for the equivalent circuit can significantly increase the convenience and effectiveness for power system calculations. (5 pages)