Voltage control method by SVC in consideration of cooperative control with LRT and determination method for rated capacity and control parameters of SVC

In recent years, the number of connection of distributed generators (DGs) such as the photovoltaic generation (PV) and wind power generation is increasing, and there is in danger of changing the voltages in a distribution system by the precipitous output variation of DGs. In this study, the authors propose one voltage control method of a distribution system by the static var compensator (SVC) in consideration of cooperation with the load ratio control transformer (LRT) of laggard control response installed beforehand in the distribution system. The proposed method may be able to make the rated capacity of SVC small and may be able to reduce the aggravation of power factor of the distribution system, by setting up the dead band of voltage control appropriately. And the authors propose one determination method of the necessary minimum rated capacity and optimum control parameters of SVC in view of the cost of equipment and high-speed controllability. In order to verify the validity of the proposed method, the numerical calculations are carried out by using a distribution system model.