Power system reliability in a deregulated environment

At the present time, the deterministic approach to transmission reliability has not been able to incorporate the effect of simultaneous power transactions on system adequacy or the effect of system security on the feasibility of power transactions. In this paper, a probabilistic approach to analyze the security of power transactions under random trading has been developed based on a region-wise approach to security analysis. In particular, the feasibility and security regions in the transaction space are derived from a transaction matrix model. By classifying each feasible transaction matrix as either secure or insecure based on prescribed system security criteria, a set of transaction-based security indices are defined. The concepts developed in this paper indicate that while the security of the transmission system is a given, the adequacy is compromised when a large number of bilateral contracts are involved.