Coordinated control of on-load tap changer and energy storage systems for voltage support in distribution networks

The use of energy storage systems is widely recognized as a key tool to create a more resilient energy infrastructure. At the same time, new technologies such as soft-open points and on-load tap changers are deserving growing attention for their potential applications in smart grids. In this paper we consider the coordinated use of on-load tap changer and energy storage systems for voltage support in distribution networks. We first formulate the optimal control problem over a given time horizon as a multi-period optimal power flow. To cope with uncertainties such as inaccurate forecasts, the optimal control problem is then inserted into a receding horizon scheme. The proposed approach requires very limited information to predict possible voltage problems and counteract them in advance. The control algorithm is tested on real data from a low voltage network featuring over- and undervoltages in the absence of voltage control. The obtained results show that the coordinated use of on-load tap changer and storage devices allows one to dramatically reduce the size of the installed storage units required to alleviate voltage issues.