Coordinated Voltage Control of Distributed Photovoltaic-Energy-Storage Systems Based on a Dynamic Consensus Algorithm

Building a novel green grid with a high power generation capacity has become the main guide for achieving the "dual-carbon goal", and new energy power generation using photovoltaics(PVs)is also in a stage of rapid development. The large-scale integration of distributed PVs has changed the unidirectional power-flow model of the traditional low-voltage distribution network, making power-flow prediction more difficult and easily causing the voltage of the PV grid-connected points to exceed the limit. Addressing the voltage overrun problem caused by the unconventional power-flow model, this paper proposes a coordinated voltage-control strategy for the distributed PV energy storage systems(ESSs), based on a dynamic consensus algorithm. Firstly, the voltage overrun of a low-voltage distribution network containing distributed PVs is analyzed. Secondly, the power-regulation characteristics of the PV inverter and ESS are considered, and a PV energy storage distributed control model is established. Then, the reactive power-utilization rate for the PV inverter and change in the energy storage state of charge(SOC) were selected as the consistency variables. Subsequently, coordinated control of the PV inverter reactive and active powers of the ESS was realized through the dynamic consistency algorithm. Finally, an 8-node 220V low-voltage power distribution network with distributed PVs was passed, followed by the verification of the energy storage by calculation examples. The results show that the proposed strategy avoids the voltage limitation problem caused by the single-link control. Compared with the traditional centralized voltage-control method, the proposed strategy performs the reactive and active powers required for voltage control among different users in proportion to the capacity. The burden of voltage stabilization of the low-voltage distribution network is evenly distributed among the users, which meets the interests of the network user group. At the same time, in different weather conditions, the highest and lowest average voltages after the proposed strategy are 1.068 and 0.911, respectively, thus, suppressing the voltage overrun problem effectively. © 2021, Editorial Board of Journal of Tianjin University(Science and Technology). All right reserved.