An adaptive p-Q management technique for grid voltage regulation using PV inverter

Network operators are currently exploring how embedded solar generation can assist with voltage regulation in the distribution network, usually by leveraging the inverter's reactive power capability. In highly resistive networks, reactive power alone may not be sufficient, which has motivated researchers to explore how simultaneous adjustment of active (P) and reactive (Q) power can result in better voltage regulation. However, the relevant published methods usually require unavailable network data as inputs and disregard the non-monotonic relation between P/Q power and voltage in resistive networks. This paper explores theoretically this relation and shows that there is always one optimal P/Q ratio that achieves maximum voltage for that particular loading condition. Surpassing this ratio results in voltage deterioration rather than improvement, which poses a risk for the relevant methods in the literature. To fill this gap, this paper introduces a new adaptive P/Q closed-loop voltage regulation scheme for PV systems and other inverter-based resources, which autonomously tracks this optimal ratio without any external inputs. This method guarantees that the resulting voltage would meet the target setpoint if feasible, or will be the maximum possible otherwise. This is the first technique to do this without any prior knowledge about the network. The proposed scheme is validated and assessed over other conventional voltage regulation methods in MATLAB/Simulink.