Research on the Application of the Bergeron Model to the Differential Equation Algorithm for Long Transmission Line

The measurement accuracy of the differential equation based distance relay for the long transmission line is deteriorated remarkably due to the influence of the distributed capacitance. In order to solve this problem, a new algorithm, which divides the long transmission line to two sections based on Bergeron method, is presented. The voltage and current at the relay location are used to calculate the instantaneous value of the current and voltage at the splitting point by the electrical-magnetic transient calculation method. The differential equation algorithm can accurately calculate the impedance from the splitting point to the fault point. The new method does not require exact characteristic of the low-pass filter. Simulation results show that this new method can calculate the impedance with high accuracy even for long transmission lines.