Compensated phase selection method based on virtual magnitude rezoning for transmission lines emanating from wind farms

Abstract

The current angle-based phase selection method (PSM) determines the specific faulty phase(s) based on the relative angles of the superimposed sequence currents at the fault point under different fault types. However, by contrast with synchronous generators (SGs), the superimposed sequence impedances of wind generators present significantly different fault features, which may deprive the unified phase angle property shown in the fault component network, and consequently accompanied by the angle offset between the respective superimposed sequence currents at the relay location and the fault point. In the meantime, the weak-infeed characteristics of the wind farm may weaken the fault signature of the current quantities. As a result, the performance of current angle-based PSM may deteriorate when applied to lines emanating from wind farms. To address these problems, this paper firstly introduces the voltage information to compensate the superimposed sequence currents such that enabling the current angle relationship to be reflected accurately at the relay location. Furthermore, to eliminate the possibility that the current angle-based PSM may provide misleading indications of faulty phase(s) under particular scenarios as it solely depends on the angle comparison, the virtual magnitude factor is constructed and utilized to optimize the fault type zones in the complex plane. Compared with the existing current angle-based PSM, some salient merits of the compensated PSM based on virtual magnitude rezoning are its immunity to the weak-infeed level, independence from wind farms’ operating status, and strong tolerance capability against fault resistance. Extensive simulation results under different fault conditions show the expected performance of the proposed PSM.