Fast Transient Security Assessment

The growth of large interconnected power systems demands a high degree of security for normal operation. This requirement emerges from the fact that the possible disturbances in large power systems could have catastrophic results. Therefore it is the duty of power system control center to retain the operating point within secure boundaries. In order to control the security of system, one has to monitor and analyze the level of system security and enhance it in case it does not fulfill the system security requirement. The pattern recognition technique which is proposed in this paper is a method suitable for fast, on-line security assessment. Most of the literature in this area concerns the use of steady state variables for identification pruposes; the use of transient measurements, however, has been found to be better suited for the fast classification of operating points with minimal error. One of the salient conclusions of this paper is that the pattern recognition technique is a serious candidate for on-line applications. This favorable conclusion is based on the inclusion of transient state variables in the feature vector. The main objective of the pattern recognition method in transient security assessment is to reduce the computational requirement to a minimum. This is done at the expense of elaborate off-line computations. The classical methodology of pattern recognition consists of defining a pattern vector x whose components consist of all significant variables of the system.