The Effect of Improved System Modeling in the Continuation Power Flow Method

Continuation power flow is one of the proposed long term voltage stability assessment methods. This method attempts to find the voltage stability limit by computing a sequence of very long term equilibrium points, using a static model derived from the equilibrium conditions of the complete non linear dynamic model. During the early stages of the Continuation Power Flow method development, the emphasis was totally addressed to the Continuation method algorithm itself and, in these conditions, the conventional load flow model was the preferred system model. As shown in this paper, using the conventional load flow model, based on unacceptable simplifying assumptions, always produces unrealistic voltage stability results, even when analyzing small academic test systems. This is shown by comparing the results of the Continuation Power Flow method, using the conventional load flow model, to the ones obtained with an improved representation of load characteristics and synchronous generator reactive power limits.