Reactive PowerControl of Grid-Connected Photovoltaic Power Generation

Abstract

In order to solve the problem of grid-connected point voltage exceeding the limit caused by large-scale photovoltaic power stations connected to the grid, and to increase the penetration rate of photovoltaics in the grid, photovoltaic power stations should have more flexible reactive voltage regulation capabilities to provide reactive power support to the grid. To this end, this paper establishes an equivalent aggregation model for large-scale photovoltaic power plants. Under the premise that the photovoltaic power station is not equipped with reactive power compensation devices and the inverter reactive power output is zero, it is analyzed that due to the existence of line and transformer impedance, photovoltaic access reduces the grid the problem of voltage stability. Based on the above reasons, this paper proposes a three-layer reactive power control strategy for photovoltaic power plants from the perspective of the cooperation between the reactive power compensation device and the grid-connected inverter. This strategy coordinates the reactive power output between the reactive power compensation device and the photovoltaic power generation unit and between the inverters of a single photovoltaic power generation unit. Under this control strategy, the photovoltaic power plant can regulate the grid voltage more effectively, and the active and reactive power losses of the grid are minimized on the premise that the grid voltage is maintained within the required range. Combined with the photovoltaic array power reduction operation strategy, the stable operation of the power grid is ensured under the premise of a certain reactive power output capacity of the photovoltaic power station. Finally, an example is used to verify the correctness and effectiveness of the strategy.