Repetitive Control Of Inverter In Distributed Power Generation System Based On Disturbance Active Compensation

Renewable energy distributed generation system is an important way to alleviate energy crisis and improve environmental pollution.As the interface device between the distributed generation system and the user and the power grid,the inverter can not only supply energy to the local load off-grid,but also transmit power to the grid connected to the grid.It is the core component of the distributed power generation system.The control performance of the inverter directly affects the quality of the output power of the distributed power generation system,and in the actual inverter system,there are inevitably system parameter uncertainty,switch conduction voltage drop,dead time,load sudden change and power grid.Impedance and other disturbances.The existence of these disturbances will lead to a decrease in the output power quality of the inverter system,resulting in a lower conversion efficiency of renewable energy.Therefore,in order to improve the control performance and robustness of the inverter system and ensure the quality of the output power,it is of great theoretical significance and application value to propose an efficient robust control design method for the inverter system.In this paper,single-phase and three-phase inverter systems are taken as the research objects.According to their different working modes in distributed generation systems,the idea of active disturbance suppression is introduced,and a repetitive control design method for inverter systems based on disturbance estimation and compensation is proposed.Improve the disturbance suppression and tracking control performance of the inverter system,and ensure that the inverter system outputs stable and reliable high-quality power in complex environments.This paper focuses on the following three aspects of research work:(1)Repetitive-control design of single-phase LC off-grid inverter system based on reduced-order extended state observerA method of designing a repetitive-control system based on reduced-order extended state observer(ROESO)is presented for a single-phase full-bridge LC-type inverter subject to parameter perturbation and load disturbances.First,the mathematical model of the inverter is derived from circuit theorem.An ROESO is constructed by making use of the measurable output voltage of the system to estimate the total disturbance including the parameter uncertainty and external load disturbance in real-time fashion.Next,a plug-in modified repetitive controller is inserted into the closed-loop system,and based on the disturbance estimate,a composite control law is constituted,which effectively attenuates the influence of the total disturbance on the output of the system and ensures the high-accuracy tracking of periodic reference input.Then,the global stability condition of the closed-loop system is established using small gain theorem.Both the parameter regulation method and design procedure of the system are given.Finally,simulation results demonstrate the validity and superiorities of the method.(2)Parameter optimization design of repetitive control for single-phase LCL grid-connected inverter system based on equivalent input disturbances compensationAiming at the single-phase LCL grid-connected inverter with disturbances such as harmonics and impedance in weak power grids,a parameter optimization design method of repetitive control system based on equivalent input disturbance compensation is proposed.First,the mathematical model of the inverter is deduced according to Kirchhoff’s law,and a full-order state observer is designed for the model,and an equivalent input disturbance estimator is established by using its estimation error to eliminate the influence of disturbance on the system output in real time.Secondly,an improved repetitive controller is embedded to construct a compound repetitive control law to achieve high-precision tracking of periodic reference inputs.Then,the global stability condition of the system is deduced by using the small gain theorem,the objective optimization function including the system tracking performance and convergence speed is constructed,and the particle swarm optimization algorithm is used to realize the optimization of all parameters in the repetitive control system based on equivalent input disturbance compensation.Synchronization optimization.Finally,the effectiveness and superiority of the proposed method are verified by simulation.(3)Parameter optimization design of repetitive control for three-phase LCL grid-connected inverter system based on disturbances observerAiming at the three-phase LCL grid-connected inverter with disturbances such as parameter perturbation and grid harmonics,a parameter optimization design method of compound repetitive control system based on disturbance observer is proposed.Firstly,the mathematical model of the system is deduced according to Kirchhoff’s law,and the disturbance observer is designed by using the information of the system model to estimate the aperiodic disturbance of the system.Secondly,an improved repetitive controller is embedded to construct a compound repetitive control law to eliminate the influence of periodic and aperiodic disturbances on the system output,and to achieve high-precision tracking of the reference input.Then,the system stability condition is deduced by using the small gain theorem,and the objective optimization function including the system tracking performance and convergence speed is constructed,and the particle swarm optimization algorithm is used to realize the synchronous optimization of all parameters in the disturbance observer-based repetitive control system.Finally,the effectiveness and superiority of the proposed method are verified by simulation.