Two-stage Voltage Coordinated Control Strategy of Photovoltaic Inverter Based on Dynamic Adjustable Droop Control Curve
In the active distribution networks penetrated by a proliferation of distributed photovoltaic(PV),traditional central and local voltage control can't solve the voltage fluctuation problem economically and effectively.Therefore,this paper proposes a two-stage voltage control strategy for PV inverters.The local control curve adopts flexible and adjustable improved volt-var(Q-V)droop control curve.The central control stage takes the weighted sum of voltage control cost and the conditional value at risk(CVaR)of voltage violations as the objective function,uses the distributionally robust optimization algorithm and the model predictive control algorithm to consider PV prediction uncertainty,and performs minute-level global collaborative optimization of each PV inverter's curtailed active power reference and adjustable nodes of the proposed Q-V droop control curve.The local control stage dynamically adjusts the reactive power output based on the Q-V droop control curve and the real-time measured local voltage.Simulation results of the modified IEEE 37 bus distribution system show that the proposed control strategy can not only centrally optimize the coordination of the curtailed active power and reactive power output of each PV inverter to avoid voltage violations but also utilize the centrally optimized Q-V droop curve in the local control stage to reduce voltage fluctuations by 40.56%,meeting different economy and robustness requirements of the distribution network operators for voltage control.
active distribution networkvoltage out-of-limithigh-proportion photovoltaicsdistributionally robust optimizationuncertaintyvolt-var droop control curve