The research, design and practice of the online special protection systems

Traditional special protection systems (SPS) take action according to generator rejection scheme (GRS) or load shedding scheme (LSS), which is simulated on an annual operation mode and therefore contributes to the following two problems: on the one hand there may be worse situations in the real-time power grid, in this case, GRS which is simulated on the basis of annual operation mode can´t ensure the security and stability of power grid. But on the other, GRS based on worse situations is so conservative that decreases economic benefits to a large extent. To solve these problems, online SPS are proposed in this paper and a test system is established at Shangdu Power Plant of State Grid in China. Based on traditional SPS, online SPS add an online calculation control centre similar to online dynamic security assessment system (DSA), improve master station devices, and formulate a communication protocol between online calculation control centre and master station, and thus online SPS which can check the effectiveness of GRS according to the real-time situations of power grid and update GRS when necessary are formed.