Research On Photovoltaic Grid-Connected Control Strategy Based On Capacitor Voltage Feedback

As an important part of solving the energy crisis and environmental problems,new energy power generation has developed rapidly with its various advantages,but the background harmonics contained in weak power grids will seriously affect the quality of the grid-connected current input to the inverter grid.Therefore,it is of great significance to eliminate the adverse effects of this background harmonic and maintain the stable work of the grid-connected inverter in accordance with the requirements.At present,it is common to use the grid voltage ratio feedforward scheme to solve this problem,but the scheme collects the grid voltage information in real time,increases the cost,and only shows good results when the number of background harmonics is not high.On this basis,this paper proposes a control strategy based on capacitive voltage feedback to optimize the traditional scheme and realize the effective control of the grid-connected inverter.Through the literature survey method,a large number of literature and books on photovoltaic power generation,MPPT,LCL type filters and grid-connected control strategies have been studied and studied,and the knowledge system has been established and improved.Simulating the output characteristics of photovoltaic cells,studying and improving the traditional conductivity increment method,it is required to maximize the use of light energy for power generation while providing constant voltage power to the back-stage grid-connected inverter system.Then,according to the requirements of this paper on the performance of LCL type filter,the parameter design and optimization,using the passive damping method as the starting point to derive the active damping method of the feedback capacitor current to suppress the resonance of the filter.A differential tracker(TD)is used to optimize PI control to improve the responsiveness of DC link voltage control and reduce overshoot.The Sparrow Search algorithm is used to optimize the parameters of the PI control so that the current control loop better tracks the reference signal.Finally,based on the capacitor current feedback control(suppression of LCL resonance peaks)and the full feed-forward of the grid voltage(suppression of grid voltage disturbances),a control strategy that can complete the two requirements can be derived from the feedback capacitor voltage alone.This control method reduces the use of sensors and reduces control costs.Relying on the MATLAB platform,the control strategy proposed in this paper is simulated under the ideal power grid,and the simulation results verify that the optimized current loop of Sparrow search algorithm has better rapidity and smaller overregulation,and also verifies the good stability and anti-interference ability of the control strategy in this paper.Then,the simulation is carried out under the condition that the grid voltage contains background harmonics,and the simulation results verify the suppression effect of the control strategy on the background harmonics in this paper,and ensure the stable work of the grid-connected inverter and the entire grid-connected system.Figure 68 Table 5 Reference 80...