An efficient continuation power flow method for voltage stability analysis

This paper presents an efficient continuation power flow-method for determining voltage stability limit of interconnected power systems. Decoupled power-flow solutions are extremely popular because of lesser storage and faster solution speed as compared to coupled power flow solution. However, it is generally believed that decoupling cannot be used near critical loading conditions. This paper shows that decoupled power-flow solution is possible even under such adverse operating conditions. It is achieved by judiciously incorporating the effects of non-negligible off diagonal submatrices through a subiteration scheme. The load parameter is included in both sets of equations. Bus angle (other than slack bus) and load parameter are used as continuation parameters for solving real & reactive power equations respectively. Results for 5-bus, 14-bus and a practical 91-bus test systems have been obtained with the coupled and proposed decoupled versions of continuation power-flow to demonstrate the validity and efficiency of the proposed algorithm.