ABSTRACT
The grid structure is complex, the traditional backup protection based on local measurements of information exist dicult setting, action duration, and it is dicult to adapt to non presupposition of change or the operating condition of the power grid structure. Furthermore, it is dicult to distinguish between line internal fault and overload when the flow transfer happens .Then it is easy to cause the cascading trip accident and increase the instability risk of the power grid under perturbation[1-2]. In recent years, with the development of wide area measurement technology (wide area measurement system, WAMS), network protection based on wide area information has received extensive attention [3]. The existing high voltage power grid main protection mainly uses different kinds of pilot protection, because of easy setting, the correct action rate high, fast speed and it is not aected by the load transfer, and the wide area information existing limitations of synchronization, propagation delay, reliability. Therefore, improving the performance of relay protection based on wide area information is mainly concentrated on the back-up protection [4].
