Coherency-based electromechanical equivalents for use in power system stability studies

This paper presents improved techniques for identifying coherent generators and consequent power system reduction for use in power systems transient stability studies. The power system equivalent model can represent effectively the dynamic and steady state states of the original power system supplying loads represented by its static characteristics. The coherency identification procedure is valid for complex and large-scale power systems on PC environments, as it require low memory and run time. The proposed identification and reduction techniques is applied to 39 bus, 10 generator NPCC system and transient stability evaluation of the proposed technique show excellent agreement between the responses of the actual system and its equivalent. The principal aim of this work is to clarify and improve the principle of coherency based power system equivalents, also it facilities the practical application of electromechanical equivalent process.