Pilot Protection With Energy Directional Comparison For The UHV Transmission Line

The advantages of pilot relay protection with directional comparison, such aslittle information data required for communication, low dependence on the speed ofcommunication, the quality of channel and strict data synchronization of two sides,have made it more suitable to be applied on HV transmission line as the mainprotection. At the same time, directional pilot relayprotection is one of the importanttopics ofrelayprotection research,thekeyelement oftheprotectionis the directionalrelay. Traditional energy directional relay fails to discriminate fault direction on theUHVlongdistancetransmissionline;andowingtothesystemresistanceis toosmall,active energy directional relay will not work when there is a fault outside thetransmission line. To resolve this problem, an energy directional relay based on faultcomponents and Bergeron algorithm for long distance UHV transmission line isproposed,andacorrespondingdirectionalpilotrelayprotectionprincipleispresented.This will greatly improve the reliability of relay protection. The operation criterionand action performance are discussed. The correctness and reliability of thedirectional protection principle and its operation criterion is proved by digitalsimulation. The energydirectional relay, whose operatingtime is less than20ms, willnot be affected by operating condition of the power system, fault resistance anddistributed capacitance, furthermore, its sensitivity will unaffected by the type orpositionofthefault.This paper also proposes an applied software ,which is based on Open SimulatingSystem of Dynamic Characteristics of Relay Protection ,mainly using advancedcomputer languages such as Visual C++6.0.The simulating of transformer protectionof the applied software was programmed by module designing method, it includestransforming module, filter module, operating characteristic module and intelligentgraphic module .Each module works independently, transforms the data fromself-defined standard interface, thus they can make the system secure and fast. Thissoftware is useful for examining the correctness of operation of relay protection andfornewprotectionprincipledevelopment.