| With the increasing global energy demand,energy crisis is becoming more and more serious and more and more scholars turn their attention to new energy sources.As an important branch of new energy,wind power generation is one of the effective ways to improve the energy structure.Compared with the horizontal axis wind turbine,vertical axis wind turbine(VAWT)has obvious advantages in urban wind power and remote area wind power system,and has developed rapidly in recent years.Therefore,it is of great practical significance to study the small wind power generation system based on vertical axis wind turbine.The analysis of the working principle of vertical axis wind turbine is the basis for the study of wind power generation.In this paper,the force analysis of the blade of H fan in the four quadrant is carried out,and the principle of doing work under the action of lift is obtained;Then,the permanent magnet synchronous generator,which matches the lOkW vertical axis fan,is chosen as the energy conversion device,and the simulation model of PMSM is established.The main circuit of this paper adopts two stage topology.The front stage is a Boost circuit,and the latter is a single-phase LCL-type grid connected inverter.The Boost circuit serves as the goal of maximum power tracking(MPPT).Maximum power tracking is achieved by controlling the Boost inductor current.For this reason,a small signal model of inductance current of Boost circuit to duty ratio is established,and controller parameters are designed.The control strategy and controller parameters of the grid connected inverter directly determine the grid connected performance of the wind power generation system.In this paper,the topology of single phase grid connected inverter with LCL filter is selected.LCL filter has resonance problem.The resonance peak appears at the crossing frequency so that the system can not be stabilized.Therefore,it is necessary to introduce damping control for the resonant peak.Without considering the control delay,the stability of active damping control system is analyzed and the controller parameters are designed.In the grid connected inverter simulation model,the designed control system is verified.Considering the existence of digital control delay in the actual system,for the fast grid connected current loop,the tiny delay can affect the dynamic and steady-state performance of the system.Therefore,a grid connected inverter model with control delay is established in the discrete domain,and the stability of the active damping control system is analyzed.Through the analysis of open-loop Bode diagram with the delay,it is found that the resonance frequency of the system is no longer coincident with the through frequency after the introduction of the delay,and the conclusion that the resonance peak makes the system unstable is no longer established.Therefore,this paper proposes a undamped control strategy,and using Bode stability criterion approach can be adopted without a sufficient and necessary condition of damping control strategy is deduced,further design steps of controller parameters and simulation results are given.An experimental platform for lOkW wind power generation system is set up in this paper.The different power levels experiments are doing in the experimental platform,through the experiments verify the effectiveness and feasibility of the damping control strategy of controller parameter design method proposed in this paper,the theoretical analysis and practical verification of organic unity,to provide reference for the single-phase LCL inverter control system design and control parameters. |
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