High sensitive start element of transmission line protection

Sensitivity of start element impacts the performance of transmission line protection. Normally, start element is affected by data window length. A start element of transmission line relay protection based on current variation sample data of three phases at the same time is proposed in this paper. It includes two criterions. The start element performance is not impacted by data window and frequency. The sensitivity of criterion proposed was superior to present criterion. The criterion performance was proven using RTDS simulations in a 1000 kV power system.