A Two-Layer Volt-Var Control Method in Rural Distribution Networks Considering Utilization of Photovoltaic Power

With the large-scale integration of poverty alleviation photovoltaic(PV) into China's rural power grids, the randomness has caused large fluctuations in the voltage with relatively weak compensation of reactive power, and the problem of voltage violation has become particularly prominent. With this concern, a two-layer volt-var control method using the reactive power regulation of the PV inverter is proposed. Firstly, the framework of “distributed control among partitions and local control in partitions” is established. In the first distributed control, based on the collected operation information of PV and load on a minute scale, to minimize the overall network loss, the volt-var droop control rate is optimized in a distributed manner, which uses decomposition-coordination method and the auxiliary problems principle. In the second local control, set the key parameters of the droop control curve adaptively, and adjust the reactive power output in real-time to suppress the voltage violation and fluctuation based on the optimized volt-var droop curve in the timescale of seconds. Finally, simulation results of a practical power grid with poverty alleviation PV show that the method can effectively suppress the voltage overrun, reduce the voltage fluctuation and minimize the network loss.