A High Speed Protection Scheme for Outgoing Line Fault of HVAC Transmission Lines Based on Low Frequency Components

To increase the operation speed of relays under the outgoing line fault conditions, this paper proposed a high-speed operation strategy based on the low-frequency transient component. The proposed method consists of two parts: the high-speed directional element and the fast outgoing line fault detection element. The measurement voltage drop and calculation voltage drop on the system equivalent impedance from relay location to backside equivalent power sources are introduced to detect the fault direction. By comparing the integration of the absolute values of residual voltage and setting voltage during a short time after the fault, the outgoing fault can be detected rapidly. The main advantage of the proposed method is its high reliability, because this method would not be affected by the high-frequency component. To overcome the impact of the capacitor voltage transformer transient characteristics on the outgoing line fault detection element, an effective method based on equal transfer processes is also presented. Finally, an extensive performance evaluation using PSCAD/EMTDC simulation corroborates the effectiveness of the proposed method. Simulation results show that the proposed method has the high operation speed under the outgoing line fault conditions. © 2020, Electrical Technology Press Co. Ltd. All right reserved.