Reliability of special protection systems

Special protection systems (SPS) have been widely used to increase the transfer capability of the network by assisting system operators in administering fast corrective actions. Compared with constructing new transmission facilities, SPS can be placed in service relatively quickly and inexpensively. However, increased reliance on SPS results in additional risks to system security. The purpose of this paper is to elucidate the importance of developing a systematic and comprehensive reliability framework for SPS. We review types of SPS and provide several examples of actual SPS failures. The need for SPS reliability assessment is discussed. Several reliability assessment methods are described, and efforts to deal with a similar problem in the process control industry are summarized. We also provide several recommendations.