Voltage control strategies of low voltage distribution grids using photovoltaic systems

In this investigation, some strategies are presented for the optimized provision of reactive power by photovoltaic (PV) systems to perform voltage regulation in a low voltage distribution grid. The optimization is based on an optimal power flow algorithm that determines the minimum amount of reactive power needed for voltage regulation, also resulting in the minimization of losses in the network. In addition to solving overvoltage problems caused by high penetration of PV systems, reactive power exchange with the superimposed medium voltage grid is also minimized. This is accomplished by performing reactive power balance with respect to a power factor set-point at the interface of medium (MV) and low voltage (LV) grids. In one strategy, the benefits of voltage support provided by battery-based energy storage system (BESS) in parallel to PV systems are also presented.