Grid Fault Resistant Operation of a Grid Interactive PV-BES System with Power Quality Enhancement

This work presents a grid interactive photovoltaic (PV) array generation unit, with the PV array (PVA) supplying the power directly at the DC link. The PVA power is maximized by keeping the DC link voltage at the maximum power point of the PVA. The system considers light single phase loads, as well as three phase loads, used in the distribution network, to be the local loads. During grid fault, the control detects the anomaly on the grid side. The system is decoupled and isolated from the utility, and the local loads are energized in an islanded mode. In case PVA power is insufficient, the integrated battery energy system (BES) is utilized. Thus, optimum PVA power utilization and robust supply to the local loads, is realized. After fault clearing, the on-line resynchronization of the system takes place, without disturbance to the local loads. The effect of various dynamic scenarios on the system is minimized, by the fast and continuous estimation of the load current weights, and the rapid update of grid currents, in the event of changing PVA power. Moreover, the grid power quality enhancement is realized by the implemented control strategy.