Abstract

The critical values of a power system are the limit values of voltage stability. These are: the values of the highest active power that load busses can take and the values of voltage amplitude and angle of the busses in this condition.  In this research, the critical values in electric power systems are defined with Simulated Annealing (SA) and Tabu Search (TS) algorithms. These algorithms are known as heuristic techniques in the literature. The research is executed on a sample of 6-bus power system. At first, as the load value in a selected load bus increased step by step, load flow is executed anytime. This process was kept until an unsolvable condition was reached, so critical bus values which are limited values of voltage stability were obtained. Secondly, using (SA) and (TS) algorithms, without increasing the load on selected bus step by step, the critical value was reached directly. It was seen that the critical bus values can be obtained easier through (SA) and (TS) which are heuristic techniques.

Key words: Tabu search, power system, voltage stability, simulated annealing.