Multiperiod Coordination of Local Voltage Controllers and Energy Storage for Voltage Regulation in Distribution Feeder-Connected Renewable Energy Sources

Connection of renewables to the distribution system is growing very rapidly. The inherent uncertainty of renewable energy sources, however, can potentially introduce operational conflicts, disrupting the typical operation pattern of local voltage regulation devices and causing system voltage rise beyond the acceptable limits. This paper describes a joint platform to maintain voltage regulation in a distribution network incorporating a large share of PV energy sources. With an objective to improve the voltage profile and minimize feeder losses, the operation of local voltage controllers and energy storage is coordinated. An optimization approach, based on the genetic algorithm, is developed to find out the optimal settings of the load tap-changing transformers and switched shunt capacitors, as well as the optimal dispatch of energy storage. The proposed method is applied to the IEEE 123 test feeder, using time series analysis over a daily, 24 h, simulation period. Test results clearly exhibit that the close coordination between the voltage control devices and energy storage scales back system energy losses, minimizes the interaction among local voltage controllers and prevents reverse power flow. It consequently upholds the voltage at the customer terminals within the statutory limits, under high penetration levels of solar-fueled generation.