Noncomunication Accelerated Sequential Tripping for Remote-End Faults On Transmission Lines

Short-circuit faults occurring close to either end of a transmission line are normally cleared with some time delay by the distance relay at the opposite end of that line. The pilot relaying schemes require communication media in order to reduce this time delay. This paper presents a noncommunication method that provides high-speed distance relaying over the entire length of transmission lines. Similar to conventional distance relays, the proposed method requires voltage and current signals at the relay location as well as the impedance parameters of the protected line as input. Accelerated sequential tripping (AST) for faults on the end-sections of the line is achieved by using the signals measured from the fault inception to several cycles after the opening of the remote-end circuit breaker (ORCB). A formula is put forward for determining the exact fault distance by using post-ORCB signals. Two indices are also proposed for detecting three-and single-pole ORCB in order to fulfill the prerequisite for accurate fault location and generating a trip command, if needed. The proposed method is validated by conducting more than 10000 simulations on the 39-bus test system using DIgSILENT PowerFactory.