Research On Single-loop Sliding Mode Variable Structure Control Strategy Of PMSG System Based On DC Grid Connectio

With the global energy transition acceleration,wind power generation technology is constantly innovating.Permanent magnet synchronous generator(PMSG)has the advantages of simple structure,low loss and high power generation efficiency,which has broad development prospects.Besides,DC grid-connected technology has the advantages of high efficiency,simple grid-connection and low transmission cost.Therefore,a single-loop SMC strategy for DC connected system is proposed to solve system slow response speed,internal parameter perturbation and external disturbance problems.The specific work of this paper is as follows:1)System modeling,simulation and experimental platform research.Firstly,PMSG system mathematical model is established,which includes wind turbine model,PMSG model and converter model.Secondly,DC grid-connected PMSG system simulation and experiment platform are built.Finally,traditional double-loop cascade PI control strategy is studied and verified by system simulation and experiment.2)Study on an inertia adaptive robust based single-loop SMC Strategy.Aiming at complex structure,poor dynamic response ability and system parameter perturbation problems of traditional double-loop cascade control strategy,an inertia adaptive robust based single-loop SMC control strategy is proposed in this paper.Firstly,based on system motion differential equation,second order system model between input voltage and rotor speed is established.Secondly,Lyapunov function among system state variablesω_m,i_d and uncertain parameterθis constructed,and system control law and inertia adaptive law are designed.Finally,effectiveness and feasibility of proposed control strategy are verified by system simulation and experiment.3)Study on single-loop SMC strategy with slow time-varying interference observer.Aiming at external disturbance problem in the second-order system model,a single-loop SMC control strategy with slow time-varying interference observer is proposed.Firstly,a Lyapunov function is constructed between slow time-varying interference signal estimation and rotor speed estimation,and slow time-varying interference observer is designed and verified.Secondly,based on the single-loop SMC strategy,a strategy combining observer and single-loop SMC controller is proposed to improve resist time-varying interference,reduce switching coefficient and chattering,and improve system transient and steady state performance.Finally,effectiveness and feasibility of proposed control strategy are verified by system simulation and experiment.4)Study on single-loop SMC Strategy with MRAC algorithm.Aiming at PMSG system parameter perturbation problem caused by magnetic field saturation,temperature change and skin effect,a single-loop SMC control strategy with MRAC algorithm is proposed in this paper.Firstly,PMSG system parameters are identified online according to MRAC algorithm.Secondly,based on single-loop SMC,a strategy combining parameter identification and single-loop sliding mode controller is proposed to improve system anti-parameter perturbation ability,reduce switching coefficient and chattering,and improve system transient performance.Finally,effectiveness and feasibility of proposed control strategy are verified by system simulation and experiment.