A comprehensive voltage control strategy with voltage flicker compensation for highly PV penetrated distribution networks

A three-level distributed voltage control strategy is proposed that keeps the voltage quality of a network within the defined standards, utilizing the control capabilities of the Photovoltaic (PV) inverters. It utilizes Flicker Control (FC), Local Voltage Control (LVC) and Co-ordinated Voltage Control (CVC), to stabilize the node voltages. FC removes the fast voltage fluctuations instantly, utilizing the PV power fluctuation and short-circuit impedance values as the controlling inputs, at the point of PV integration. LVC provides a robust response to the voltage violations outside the dead band while enhancing the voltage quality, utilizing local information in formulating inverter set points for reactive power support and real power curtailment strategies. Lastly, CVC is initiated whenever there is a voltage violation or PV curtailment at any of the network's nodes. CVC utilizes a multi-agent system to reduce curtailment and network losses, while utilizing the coordination among various droop controls, to fully utilize the inverter's Q-support capability. The effectiveness of the proposed voltage control architecture is demonstrated on a 33-bus medium-voltage distribution network, hosting 13 PV systems.