Transmission switching to relieve voltage violations in low load period

With the development of modern power system, extra-high voltage (EHV) AC transmission lines are widely used. Because of large capacitive charging, long EHV AC lines may cause voltage violations in low load period. The leading-phase operation of synchronous generators and switching on shunt reactors are two common measures to relieve voltage violations in low load period. In this paper, we propose that opening some EHV lines in low load period, namely transmission switching is a more economic and efficient measure. The problem of finding an optimal topology to relieve voltage violations in low load period is formulated as a mixed integer non linear programming problem. After some simplifications, the model is converted to an easily solved mixed integer linear program. The modified IEEE 30-bus test system is used to evaluate the applicability and effectiveness of the proposed method.