Evaluation and Improvement of Total Transfer Capability in an Interconnected Power System

With deregulation, the total transfer capability (TTC) calculation, which is the basis for evaluating available transfer capability (ATC), has become very significant. Total transfer capability (TTC) is an important index in power markets with large volume of interarea power exchanges and wheeling transactions taking place on hourly basis. Its computation helps to achieve a viable technical and commercial transmission operation. The aim of the paper is to evaluate TTC in the interconnections and also to improve it using reactive optimization technique and unified power flow controller (UPFC) device. TTC computation is carried out considering normal and contingency conditions such as single line, tie line and generator outages. Base and optimized results are presented, and the results show how reactive optimization and UPFC help to improve the system conditions and tie flows. Repeated power flow method is used for transfer capability computation due to its ease of implementation. A case study is carried out on a 72-bus equivalent system, which is a real-life system, a part of Indian Southern grid. The developed procedure is successfully applied to the three-area 72-bus system. Parameters like voltage magnitude, L-index, minimum singular value and MW losses are computed to analyze the system performance.