A recursive harmony search algorithm for security constrained transmission expansion planning

This paper proposes an enhanced recursive harmony search (HS) algorithm for the solution of the static transmission expansion planning (TEP) in deregulated environment considering security constraints. The modification of the recursive HS method in comparison to the traditional HS algorithm includes: i) the introduction of a variable bandwidth in the memory consideration and the pitch adjustment phases in the improvisation step of the algorithm and ii) the possibility of restarting the algorithm after the maximum number of improvisations is reached keeping the best solutions of the previous algorithm run. In this way, the probability of finding the optimum solution of the TEP problem is highly increased without burdening the computation time of the algorithm. The proposed recursive harmony search algorithm is tested and evaluated on Garver´s test system for the classic static TEP problem. Moreover, a new cost-benefit TEP formulation is introduced which is solved by the proposed HS algorithm and tested on IEEE 24-bus reliability test system considering annual system operation.