Sensitivity-Based Local-Central Combined Voltage/Var Control of Photovoltaic Inverters Without Impedance Imformation

With the increasing energy demand in society, photovoltaic (PV) power generation has gained significant promotion. As distributed PV systems become increasingly integrated into low-voltage distribution networks, challenges regarding voltage limits emerge within these distribution grids. Traditional voltage/Var control (VVC), relying on system impedance parameters, utilizes the surplus capacity of PV inverters to regulate voltage. However, obtaining precise parameters of lines and loads within low-voltage distribution networks poses a significant challenge, thereby limiting its practical implementation. This paper introduces a novel PV inverter VVC method that circumvents the need for impedance information. By analyzing voltage and power information from monitorable nodes within the distribution network, the proposed method can estimate the sensitivity of reactive power injection to voltage magnitude. Building upon this analysis, an effective voltage/var controlling scheme is designed to mitigate the voltage violation.