Research On Photovoltaic System Participating In Grid Active Power Support Technology Based On Unitized Reconstructio

In recent years,the photovoltaic power generation industry has been booming,which is of great significance for solving the global energy crisis,curbing global warming trend and implementing the carbon peaking and neutrality strategy.However,with the increasing photovoltaic penetration of the power grid,the issues of photovoltaic about difficult to predict,weak controllability,strong volatility,have brought more uncontrollable risks to the grid flow stability,power balance and other aspects.The State Grid Corporation has issued relevant standards,requiring that photovoltaic power stations should have the function of regulating active power and response to active power dispatching command.Therefore,for the sake of active power regulation of photovoltaic plant and the response to active power dispatching,this paper carries out the research of grid active power support technology of photovoltaic system.In field applications,large-scale photovoltaic arrays are often affected by partial shading condition caused by cloud shadows,surrounding buildings or plants,dust,etc.,and thus reducing the output power.Photovoltaic systems can increase the active power output under partial shadows via array reconfiguration.Therefore,under partial shading conditions,the photovoltaic system can regulate the active power output in real time via array reconfiguration to respond the active power dispatching command issued by the power dispatching center.Based on this,this paper proposes the grid active power support technology of photovoltaic system based on unitary reconfiguration.Above all,this paper studies the influence of irradiance and temperature on the output characteristics of photovoltaic array,and finds that the photovoltaic array active power decreases with the decrease of irradiance and the increase of operating temperature.Secondly,in view of the high complexity of large-scale photovoltaic array reconfiguration and the slow algorithm convergence,this paper establishes a photovoltaic array unitary reconfiguration model to improve the reconfiguration efficiency.Also,it proposes an improved switching matrix and selfrectify strategy,which effectively reduced the number of switches by more than 50% and the number of invalid switch actions by up to 65%,thus reducing the array reconfiguration time,improving the response speed of active power dispatching and prolong the service life of switch matrix.Then,a multi-population information exchange strategy is designed.Based on this strategy,an improved prairie dog optimizer is developed and applied to the study of grid active power support technology of photovoltaic system based on unitary reconfiguration.In order to verify the active power support effect of the proposed technology,two case studies of constant and time-varying active power dispatching order are designed in this paper.Simulation tests are carried out in five partial shadow modes,namely long-narrow,long-wide,short-narrow,shortwide and random shadow,respectively.Four evaluation indexes are proposed to evaluate the response accuracy of the proposed algorithm quantitatively.The results show that compared with the other six heuristic algorithms,the proposed algorithm has better optimization ability.Moreover,the power response deviation is about 0.20% ～ 0.39% and 0.72%～1.03% in response to constant and time-varying active power dispatching,which effectively verifies that the proposed technique has the ability to the active power support to the grid.