Optimal reactive power compensation planning with improving voltage stability margin in deregulated environment

More and more power utilities face the voltage stability security, as an important way to improve voltage stability margin. The reactive power compensation planning are received more and more attention. The panning includes two parts, one is to select the optimal compensation location, the other is looking for the optimal capacity. In this paper the optimal compensatory sites are selected by using the left eigenvector of the minimum eigenvalue of the Jacobian and the sensitivity of VAr to reduce the system active power loss, and the optimum compensation capacity are gained by multi-objective immune algorithm (MOIA). In the course of solving, the encoding and the decoding of antibody and the generation of the antibody are studied in detail; at the same time, a new method of calculating the affinity is put forward. This algorithm is tested in IEEE30 bus system and a practical system, the result indicates the proposed algorithm is valid to reduce active power loss and enhance the system voltage stability margin.