Efficient Current-Based Directional Relay Algorithm.

Directional relays have a key role for protection of transmission and distribution networks. They are used as supervisory element for distance and overcurrent protections. Therefore, accuracy and performance of these protections are dependent on the performance of directional relays. In this paper, a high-speed current-based directional algorithm is presented. For a specified interval, the fault current samples are multiplied by corresponding prefault current samples and summation of the results is calculated as a criterion. Sign of the summation and direction of power flow at normal condition determine fault direction. In spite of most high-speed techniques, just accurate current transformers are needed to obtain the criterion and determining normal power flow can be relegated to simple voltage transformers at steady-state condition. The method is evaluated using plenty of simulations and experiments. Also, performance of the proposed algorithm is compared with some similar approaches. The results confirm reasonable accuracy, speed, and simplicity of the proposed method. [ABSTRACT FROM AUTHOR]