A New Optimising Concept to Ramp-Rate Constrained Economic Dispatch with Prohibited Operating Zones

This paper presents an effective "lambda-logic" based algorithm for solving economic dispatch (ED) problem in power systems. Some of the non-linear characteristics of the generator, such as prohibited operating zones and ramp-rate limits are considered using the proposed method in practical generator operation. In this paper, a two executions of "lambda-logic based" algorithm is used. In the first execution, it determines the dispatch of generators considering ramp-rate limits and without considering prohibited operating zones. If there is no violation, the optimal dispatch is obtained. If there is a violation in units, set there limits, and then it uses an efficient approach to determine the most advantageous space using the average power of prohibited operating region. In the second execution, it obtains the optimal dispatch for the remaining units considering ramp- rate limits. The proposed method is very efficient for both small and large size of generating units with prohibited operating zones and ramp-rate limits in the problem and it remarkably reduces the computation time. The proposed algorithm has been tested successfully on 15 units and 40 units with some of the on-line units having prohibited operating zones and ramp-rate limits. The test results are reported in this paper.