Reactive power/voltage control in a distribution substation using dynamic programming

The reactive power/voltage control in a distribution substation is investigated. The purpose is to properly dispatch the shunt capacitors and onload tap changers at the distribution substation based on the forecast hourly loads of a main transformer and its primary bus voltage such that the reactive power flows through the main transformer, and the transformer secondary bus voltage deviations from the desired values can be minimised. Practical constraints on secondary bus voltage limits and the maximum allowable number of switching operations in a day for the onload tap changers are taken into account. An approach based on dynamic programming is presented to reach the desired dispatching schedule. To demonstrate the usefulness of the proposed approach, reactive power/voltage control in a distribution substation within the service area of Taipei City District Office of Taiwan Power Company is performed. It is found that a proper dispatching schedule for the shunt capacitors and onload tap changers can be reached by the proposed method.