Research On Reactive Voltage Control In Large-Scale Photovoltaic Power Plant Centralized Access Area

The development and utilization of large-scale photovoltaic power plants can effectively alleviate existing energy crises and reduce the cost of energy use.However,with the increase of photovoltaic grid-connected capacity,the impact of the stochastic fluctuation characteristics of photovoltaic power generation on the stable operation of the power grid cannot be ignored.Among them,the voltage stability problem is one of the most concerned issues,it is necessary to conduct an in-depth study on the reactive voltage control of grid-connected photovoltaic power plants.In-depth study of the basic working principle of inverters and photovoltaic cells can effectively solve the voltage fluctuations in the grid-connected points of photovoltaic power plants.Based on the establishment of mathematical models of inverter and photovoltaic cells,the overall photovoltaic power plant model is built to provide theoretical support for the research of reactive power voltage control of photovoltaic power plants.Aiming at the wide variety of reactive power sources included in photovoltaic power plants,the reactive power compensation devices in photovoltaic power plants and the reactive characteristics of inverters are studied separately,and the control model is established to verify the reactive power output characteristics of SVG and inverter.In the context of large-scale photovoltaic power plants,grid-connected inverters and reactive power compensation devices SVG are used as reactive sources.Firstly,according to the large-scale photovoltaic power station model,the influence of grid voltage static stability is studied.Secondly,relying on the voltage amplitude of the grid connection point to adjust the real-time reactive power difference of the photovoltaic power station,coordinate control of the reactive power compensation device and the photovoltaic power generation unit to ensure the stability of the voltage at the grid connection point.In order to reduce the power loss and reduce the reactive power transmission of the internal collector line,it is necessary to give priority to the reactive power compensation device.When the reactive power compensation device is full,the remaining reactive power is allocated to each photovoltaic power generation unit,and the reactive power distribution between the photovoltaic power generation units follows the voltage/reactive sensitivity analysis theory,and the reactive power is used to control the reactive power of the photovoltaic power generation unit.Output,thereby increasing the system's voltage regulation capability.This paper focuses on the impact of large-scale photovoltaic power generation system on grid voltage stability,and lays a theoretical foundation and decision support in improving the voltage stability of photovoltaic system and increasing the PV system permeability.