Coordinated Control of a DG and Voltage Control Devices Using a Dynamic Programming Algorithm

This paper presents a new control method, in which a distributed generator (DG) actively participates in steady-state voltage control, together with an under-load tap changer (ULTC) and shunt capacitors (Sh.Cs). In the conventional DG control method, the integration of DGs into a distribution power system increases the number of switching operations of the ULTC and the Sh.Cs. To solve this problem, this paper proposes that the DG output voltage be dispatched cooperatively with the operation of the ULTC and the Sh.Cs, based on load forecasts for one day in advance. The objective of the proposed method is to decrease the number of switching device operations, as well as to reduce the power loss in the distribution lines, while maintaining the grid voltage within the allowed range. The proposed method is designed and implemented with Matlab, using two different dynamic programming algorithms for a dispatchable and a nondispatchable DG, respectively. Simulation studies demonstrate that the objective can be achieved under various grid conditions, determined by factors such as the DG output power characteristics, the location of the DG-connected bus on the feeder, and the load profile of the feeder containing the DG.