Research On Finite Control Set Model Predictive Control Of Three-phase Grid-connected Inverter

In new energy power generation,the performance of the three-phase grid-connected inverter directly affects the utilization efficiency of new energy and the grid-connected power quality.For many years,high-performance control methods have been the focus of scholars’ research.Model predictive control is a control algorithm that originated from industrial production process control.This algorithm has many advantages such as low requirements for system modeling accuracy,strong steady-state and dynamic performance,no need for complex parameter calculations,and flexibility of cost functions.Model Predictive Control Finite Control Set(FCS-MPC)has attracted wide attention from many scholars.First,the basic concepts and characteristics of FCS-MPC are introduced.Based on the current research status of finite control set model predictive control,the main problems to be solved in this paper are drawn: the effect of action delay and the large amount of system calculation.The control principle of FCS-MPC is described in detail,and its basic principle and cost function are described respectively.At the same time,mathematical models of three-phase two-level gridconnected inverters in different coordinate systems are established.By analyzing the influence of the action delay of the traditional FCS-MPC,in order to solve the problem of the action delay of the FCS-MPC,an improved FCS-MPC-"two-step prediction" method is used to predict the current.The predictive control is compensated for delay by increasing the number of predictions,and the future reference value in the cost function is estimated by the vector angle compensation method to obtain better step response performance.Combined with simulation,the effectiveness of the improved control strategy algorithm is further verified,and the quality of the inverter output current waveform is improved.Secondly,in view of the large amount of system calculation of the FCS-MPC control strategy,based on the improvement of the FCS-MPC control strategy,an event-triggered limited control set model predictive control(Event Triggered-FCS-MPC,ET-FCS-MPC)method,this method only triggers the FCS-MPC scheme when the grid-connected inverter status error exceeds the preset threshold,otherwise,the FCS-MPC scheme will be suspended,and the control signal and switching behavior will be the same as the previous moment the same.Therefore,compared with the traditional method,this method has the advantages of less calculation and less switching actions.In addition,the additional benefit of reducing the switching loss of the power switch tube is brought,and the system efficiency is improved.Finally,a three-phase inverter simulation model was established in MATLAB/Simulink,combined with simulation to further verify the effectiveness and feasibility of the control strategy algorithm used in this article,the simulation results show that the control strategy algorithm can achieve the expected goal,and verify The correctness of the theoretical analysis.