Multi-objective congestion management in a deregulated power system ensuring system stability

Congestion of transmission lines is a key challenge for the system operator in the open access regime and is usually managed by rescheduling of generators and demands. The changes in schedule due to Congestion management (CM) may cause stability margins to shrink to unacceptable levels. Stability issues must, therefore, be considered during congestion management. This paper presents a multi-objective formulation of the CM problem in a pool model, with the competing objective functions of minimizing CM cost, maximizing Loading Margin (LM) (which is employed as an index of voltage stability margin) and Transient Stability Margin (TSM). Nondominated Sorting Genetic Algorithm II (NSGAII) is employed to achieve the best trade off among three objectives. Fuzzy decision maker is made use of to extract the best compromise non-dominated solution. The proposed method has been tested on WSCC 9-bus System and results show the efficacy of the proposed technique in minimizing the cost of congestion management and maintaining sufficient level of stability margin while alleviating congestion in the transmission lines.