Load Flow Equivalents for Decentralized Monitor and Control of Power Systems

Abstract

Load flow calculation on electric power systems is one of the most fundamental analysis in system operation and planning. There are many purposes to calculate load flow solutions, and the contingency evaluation is representative one.
In contingency evaluation, it is needed to repeat load flow calculation for tremendous patterns depending on branch or generation outages, then computing efforts are generally very heavy. So, various techniques have been proposed to reduce computing time especially by adopting equivalencing the external network. On the other hand, network equivalents techniques also become important nowadays from the viewpoint of necessity of decentralized monitor and control on bulk power systems.
This report describes newly developed method of load flow equivalents based on Ward equivalent for both direct (DC) solution and precise (AC) solution. Numerical results are also shown to clarify the accuracies and practicality of proposed method through the comparison to representative REI approach.