Stability Analysis and Stabilizing Procedure for A Frequency Dependent Tansmission Line Model

A frequency dependent transmission line model, developed in 1975 and referred to in the BPA Electro-Magnetic Transients Program (EMTP) as 'Semlyen Setup', has persistently exhibited an anomaly frustrating to its users. When the line model is isolated from the rest of the power system model by switch action it responds with an apparently linearly increasing voltage rather than a constant one corresponding to the locked charges. Experimentation has shown that the anomaly is associated with the frequency dependent characteristic admittance of the model. The paper gives the theoretical analysis of the stability of simulation, indicates the cause of the anomaly and recommends a solution. This has been tested and implemented in the EMTP.