Sensitive ground fault detection in compensated systems (arc suppression coil). What is influencing the sensitivity?

摘要

High-impedance Earth fault detection is always a topic for any kind of neutral point treatment in electrical power line systems. For compensated networks, it is the disseminated opinion that fault detection is too difficult. The authors aim to show it is simpler and much more sensitive compared with other neutral point treatments. Especially for the sensitivity of classical fault detection methods such as wattmetric (cosa????), admittance method and transient method, the question is what sensitivity to expect. This study gives a basic overview of the mentioned detection methods, their achievable sensitivity and the requirements for that. Since the fault detection should work with natural signals only, methods with artificial signal injection during the fault are not included. The necessary measurement accuracy for different detection methods will be considered as well. Basic aspects with practical measurements taken during Earth fault tests in a compensated system with overhead lines are compared. The fault impedance was &5a??k?? in the 10a??kV system. The earth fault tests have been undertaken with Energijos Skirstymo Operatorius. The device Erdschluss Ortungs Relais-3D (EOR-3D) has been tested regarding the fault detection sensitivity. They will show that classical methods can achieve high fault detection sensitivity.