Evaluation of Distance Protection Performance applied on Series Compensated Transmission Lines using Real Time Digital Simulation

The protection of series compensated lines is considered to be one of the most difficult tasks for engineers. The series compensation affects the impedance measurement such that special considerations are necessary in the application of distance protection. In order to evaluate the performance of distance protective relays that will be applied in 500 kV Brazilian transmission system, real time closed-loop digital simulations were realized. The closed-loop testing approach enables the, evaluation of not only the protective relay but also the response of the system to the relays action. Several complex situations were simulated and analyzed. This provided an opportunity to optimize the relays settings and protection scheme, therefore saved time during commissioning and assurance of satisfactory performance. The main objective is to present an evaluation of distance protection when applied to protect series compensated transmission lines, presenting not only the tripping times, but also verifying all the performance and functionality of a modern protection system