Current Feed Forward Control Algorithm For Voltage Source Inverter

Wind power,solar power and other new energy generation presents volatility and randomness.Power electronics technology has become a key technology to buffer the contradiction between random energy and grid stable energy.Among them,voltage source inverter is an important power conversion device.For the response speed,control accuracy,tracking performance,anti-interference performance and stability of the inverter,the control technology plays a key role under the condition of a certain circuit topology.In this paper,single-phase voltage source inverter and three-phase voltage source inverter are taken as the research objects,and the load current feedforward control method is studied(1)A current feedforward control algorithm with single voltage loop is proposed.Firstly,the source of current feed-forward control algorithm for inverter system is given,and the feed-forward control law of intermediate variables for MIMO(multiple input multiple output)nonlinear system is discussed.Secondly,the feed-forward control law of intermediate variable is applied to the current feed-forward control of single-phase voltage source inverter.The mathematical model of current feed-forward control of single-phase voltage source inverter is established.After substituting the control algorithm into the transfer function of closed-loop system,the following performance and anti-interference performance are analyzed.The stability of the algorithm is analyzed by Lyapunov second discriminant method.Finally,the rationality and effectiveness of the algorithm are verified by simulation and experiment.(2)Compared with single-phase voltage source inverter,three-phase voltage source inverter is a coupled MIMO system,which is more widely used in industry.Therefore,load current feedforward control method is extended to three-phase voltage source inverter.Firstly,the mathematical model of three-phase voltage source inverter is established by using switching period averaging operator,and the d-q model of three-phase voltage source inverter is obtained by using d-q transformation.The feed-forward control law of MIMO nonlinear system with intermediate variable is applied to three-phase voltage source inverter system.The mathematical model of current feed-forward control is established,and the following,anti-interference and stability of closed-loop control are discussed.Finally,the rationality and effectiveness of the algorithm are verified by simulation and experiment.(3)The optimal design of inverter filter parameters under wide load condition is discussed.The transfer function of LC filter is analyzed,and the selection basis of cut-off frequency is obtained from the baud diagram of second-order oscillation.On this basis,the mathematical model is established from the perspective of reactive power,and the functions of reactive power of band resistive inductive load and resistive capacitive load are obtained,and the inductance value of the lowest reactive power is obtained by deriving this function.According to the relationship between cut-off frequency and inductance,the corresponding capacitance value is obtained.The rationality of this method is verified by simulation and experiment.