Time-domain distance protection of transmission lines based on the conic section general equation

This paper presents the development, implementation, and testing of a time-domain distance protection algorithm based on the behavior of voltage and current signals over time and on the conic section general equation that describes this behavior. The authors used six existing electrical systems modeled in ATP/EMTP to perform fault simulations varying the fault type, phases involved, fault resistance, inception angle, and fault location. Besides, the authors carried out a sensitivity analysis regarding the sampling frequency influence, noisy data, dynamic behavior of capacitor voltage transformers, power swings, and close-in faults. Finally, the authors tested the proposed method against an actual fault event on a 500 kV Brazilian transmission line. The results presented in this paper indicate that the proposed solution is robust, fast, accurate, secure, and dependable.