AN APPROACH TO SECURITY EVALUATION OF COMPOSITE POWER SYSTEMS

A bulk electric power system is composed of generating units, transmission lines, transformers and loads. The complexity varies from one system to another, but the associated technical problems are basically the same. It is not uncommon to find power systems which have more than ten thousand buses. As a rule of thumb, about one fourth of these buses will have generators connected to them. A typical planning procedure involves examining the adequacy of the transmission and generating capacities by testing the ability of the system to supply the load demand under specified contingencies. The planner usually studies the stability of the system for a set of disturbances such as a three phase fault near a generation bus. This planning procedure does not account for the probabilistic or stochastic nature of system behavior, of customer demands or of component failure. The need for probabilistic evaluation of system behavior has been recognized for some time and techniques are slowly being developed. There is a considerable interest in the application of probability techniques in quantitative evaluation of power system reliability. Probability methods are being used extensively in the area of static adequacy assessment, however, their application to power system security evaluation have not received the same degree of attention. In this thesis, an approach to security evaluation of a composite power system is proposed. This approach incorporates both steady state and transient state considerations in the reliability evaluation of composite power systems