Reliability of special protection systems

Special protection systems (SPS) have been widely used to increase the tran sfer capability of the network by assisting system operators in administeri ng fast corrective actions. Compared with constructing new transmission fac ilities, SPS can be placed in service relatively quickly and inexpensively. However, increased reliance on SPS results in additional risks to system s ecurity. The purpose of this paper is to elucidate the importance of develo ping a systematic and comprehensive reliability framework for SPS. We revie w types of SPS and provide several examples of actual SPS failures. The nee d for SPS reliability assessment is discussed. Several reliability assessme nt methods are described, and efforts to deal with a similar problem in the process control industry are summarized. We also provide several recommend ations.