Abstract:

This paper proposes a new algorithm for the reactive power optimization with the constraints of voltage stability margin, by which the static voltage stability margin is effectively increased and the active power loss is re- duced via the adjustment of control variables. In this method, the reactive power optimization problem is decom- posed into two sub-problems. One is the nonlinear reactive power optimization and the other is the voltage stability margin and its sensitivity analysis of control variables. The two sub-problems are then alternately solved to obtain the optimal solution, respectively with the nonlinear primal-dual interior-point method and the continuous power flow method. The proposed method is of high calculation speed and good universality for various real systems. The applications to IEEE 14-bus, 30-bus and l l8-bus systems demonstrate that the proposed method is effective and that, when the load increases in a particular mode, the bifurcation type of a system may change between a limit-in- duced one and a saddle-node one due to the change in reactive power flow.

Key words: static voltage stability, reactive power optimization, continuous power flow method, stability margin, sensitivity analysis