Active Disturbance Rejection Control Strategy For Microgrid Inverter

The development of renewable energy,especially clean energy,has become the focus of energy research,and countries are rapidly planning the large-scale development and utilization of renewable energy.The development of microgrid technology promotes the consumption of renewable energy,reduces energy transmission loss and improves power supply reliability.At the same time,distributed energy is connected to AC microgrid through power electronic equipment(microgrid inverter),which greatly increases the difficulty of microgrid control under complex conditions.Therefore,this paper takes the full power converter in the wind power microgrid system as the research object,and carries out the following work.Firstly,the meaning and development history of microgrid are described,and the control strategy of microgrid inverter is summarized in detail;The mathematical models of microgrid converter in three-phase static and two-phase rotating coordinate systems are constructed.Secondly,because the influence of bus voltage filter is not considered in the voltage outer loop of microgrid inverter based on Active Disturbance Rejection Control(ADRC),the amplitude and phase difference exists between the control feedback and the actual system output,resulting in the degradation of the steady-state and transient performance of the system.A novel linear extended state observer(LESO)is proposed to estimate and compensate the unfiltered bus voltage,so that the bus voltage ripple caused by the inertia link can be compensated.Thirdly,nonlinear active disturbance rejection control(NLADRC)is integrated with grid connected inverter control system.Because the nonlinear structure has "large error,small gain";The characteristics of "small error,large gain" can effectively improve the immunity and tracking performance of the whole microgrid,but NLADRC still has many problems,such as many parameters to be set,unclear physical meaning and so on.In this section,the anti-interference mechanism is analyzed,and the influence of system parameters on the transient response of the network is analyzed,and the adjustment methods of system parameters are summarized.Finally,Matlab/Simulink and wind power microgrid platform are used for simulation and experimental verification.The results show that the improved LESO and NLADRC control strategies can effectively improve the fault ride through performance of microgrid inverter under grid voltage and generator side fault conditions.