| With the rapid development of renewable energy sources,distributed photovoltaic power generation systems have attracted widespread attention.As the core power conversion component,the grid-connected inverter topology and corresponding control strategy have a significant impact on the reliability and efficiency of the entire distributed power generation system’s stable operation.In view of the advantages of non-isolated inverters,such as simple structure,high efficiency and low cost,this paper designed a single-phase two-stage photovoltaic power generation system based on H6 non-isolated grid-connected inverters.And the following research was carried out for the purpose of improving the system’s stable operation efficiency and grid-tied power quality.First,the working principle of the H6 inverter is introduced,the advantages of choosing the H6 topology is clearly defined,a comprehensive control framework for the single-phase photovoltaic grid-connected power generation system with pre-stage boost and post-stage inverter are built.And the parameter design of Boost and LC filter circuits were completed as well.Then,aiming to solve the challanges of the traditional maximum power point tracking technology,such as low conversion efficiency,a particle swarm optimization-based beast search algorithm was proposed,which the the global search idea of particle swarm was used to optimize the position and moving direction of the beetle individuals.After building a photovoltaic cell Simulink simulation model,analyzing its output characteristics,explaining the principles of the maximum power point tracking algorithm and setting the algorithm parameters,the simulation module was successfully established.Simulation results show that the proposed control strategy can quickly find the maximum power point and effectively reduce the output oscillation amplitude regardless of sudden changes in the external environment.In addition,in view of the problems of high computational cost and difficult design of the proportional multiple quasi-resonant control strategy,a proportional repetitive control is proposed for H6 inverters.In this control scheme,the repetitive controller runs in parallel with the proportional controller.The repetitive controller with less design parameters and simpler structure is used to replace the multi-resonance controller to improve the system’s steady-state harmonic compensation capability.The proportional controller is mainly responsible for improving the transient performance of the system.The detailed theoretical stability analysis and parameter design of the proposed control scheme is carried out.Combined with the generalized second-order integrator phase-locking technology,the Simulink comparison simulation of the post-current inner-loop control was completed,which verified the excellent harmonic suppression ability and the robustness against grid disturbance.Finally,the pre-stage boost and post-stage inverter modules are connected by the voltage outer loop control,the overall Simulink simulation model of a single-phase two-stage grid-connected H6 inverter was successfully built.The simulation results further verified the feasibility of the proposed scheme. |
