Research On Efficiency And Stability Of Distributed Photovoltaic Inverter

Today,energy depletion and environmental pollution are becoming increasingly serious.Photovoltaic utilization has become a hotspot for the development of countries around the world,and improving photovoltaic power generation efficiency and enhancing the stability of photovoltaic grid-connected inverters have become key factors restricting photovoltaic power generation technology.This article takes single-phase photovoltaic grid-connected inverters as the research object,and conducts theoretical and experimental research on photovoltaic grid-connected inverter power generation efficiency and grid-connected inverter stability.First of all,this paper analyzes the topology and principle of photovoltaic grid-connected inverters in detail.Second,this paper addresses the shortcomings of MPPT algorithm: the perturbation observation method is easy to oscillate at the MPP point during steady state and cannot be adjusted after the step is fixed.An optimization and improvement of the algorithm is proposed.The fuzzy controller is introduced into the algorithm.Simulation analysis shows that compared with the traditional disturbance observation method,the improved disturbance observation method has better stability and tracking rate when the external temperature and light intensity change.Improved,can better track the maximum photovoltaic power.In addition,LCL-type filters have the advantages of small size and good filtering performance,so they are widely used in photovoltaic grid-connected inverters.However,since the LCL filter has a resonance spike at the resonance point,it will affect the stability of the grid-connected inverter.Aiming at the stability of the LCL grid-connected inverter,this paper proposes an active damping scheme based on the loop feedback of the filter capacitor voltage to suppress the resonance spike of the LCL filter.Under weak grid conditions,due to the presence of grid impedance,the resonance frequency of the LCLfilter will move to the low frequency direction,resulting in a decrease in the stability margin of the grid-connected inverter and poor stability.In view of this situation,this paper proposes a control strategy based on virtual grid resistance to increase system damping and improve the robustness of grid-connected inverters under weak grid conditions.Aiming at the control of grid-connected current loop,this paper proposes a PIR control strategy.Compared with traditional PI control and PR control,PIR control exhibits better robustness in both dynamic performance and steady-state performance.Finally,on the established experimental platform,the improved scheme proposed in this paper is verified by experiments,which proves the correctness of the proposed theory.