Research on Optimal Management and Flexible Control Method of Reactive Power Voltage for Distributed PV Users in Distribution Station Area

With the large-scale grid-connection of distributed PV, the distributed PV users at the end of the low-voltage distribution station area have the problem of voltage exceeding the limit, and even the situation of burning the photovoltaic inverter and the distribution transformer, which seriously affects the operation safety of the distribution network. Aiming at the problems such as high cost and difficult implementation of existing control methods, a reactive power and voltage optimal management and flexible control method and system of distributed photovoltaic inverters based on distribution transformer supervisory terminal unit (TTU) of the station are proposed. Based on the EC-IoT technology architecture, the method and system make full use of the residual reactive power capacity of photovoltaic inverters and combine with the reactive power compensation equipment in the station area to propose a unified and coordinated control strategy for voltage control in the station area. Finally, the actual output and load data of distributed PV users in a distribution area of China are used for simulation analysis, field tests and applications. The application results show that the distributed resource coordination control APP embedded in TTU proposed in this paper can realize real-time and accurate adjustment of the reactive power output of photovoltaic inverters, without transforming the distribution network lines or restricting the distributed photovoltaic active power output, effectively improve the voltage quality of the station area, and avoid the problems such as frequent start and stop of the inverter caused by grid-connected overvoltage of photovoltaic users, and voltage fluctuations or even oscillations caused by the self-regulation of multiple inverters and other problems. The method proposed in this paper provides a good reference case for solving the problem of end-user voltage over-limit caused by large-scale distributed PV grid-connection.