Research On Stable Output Control Method Of Hydraulic Wind Turbine

Wind power fluctuations have a significant impact on the quality of the power output from the wind turbine and the stability of the grid.Since wind energy is intermittent,volatility,etc.,and a hydraulic unit type parameter nonlinear time-varying its existence,will cause fluctuations in the output power.Therefore,this paper takes hydraulic wind turbines as the research object.Aiming at the output power fluctuation caused by disturbances inside and outside the system,the power smoothing control research is carried out on the models based on wind turbine energy storage and additional hydraulic energy storage respectively.This paper mainly introduces the working principle of hydraulic wind turbine and analyzes its operating characteristics.Firstly,a mathematical model of wind speed,a mathematical model of a wind turbine,and a mathematical model of the hydraulic main drive system are established.Then the state space model of hydraulic wind turbines before and after grid connection is established.The state space model after grid connection lays the foundation for subsequent control strategies based on wind turbine energy storage and hydraulic energy storage.This paper studies the power smoothing control of hydraulic wind turbines without additional energy storage devices.By controlling the storage and release of the kinetic energy of the rotor,the smooth power control of the hydraulic wind turbine is realized.Firstly,the power transmission characteristics of hydraulic wind turbines are analyzed.Aiming at the influence of internal and external disturbances such as wind speed changes,time-varying unit parameters and self-multiplying nonlinearity on the output power,the Active Disturbance Rejection Control Strategy(ADRC)is adopted,and the control parameters are tuned through the linear quadratic regulator(LQR)And the stability of the power closed-loop control system is analyzed.Finally,it is verified by simulation that the active and smooth control of unit output power can be achieved by adjusting the kinetic energy of the wind turbine.This paper focuses on the influence of time-varying internal parameters of hydraulic wind turbine power closed-loop control system on power output.The sensitivity analysis of the power closed-loop control system is carried out.The first-order trajectory sensitivity analysis method based on the system state space description is used to analyze the power control system.The parameters that may change during the operation of the system are selected,and the sensitivity equation of each parameter to the power closed-loop control system is established and solved.Through calculations,the quantitative effects of different parameters on the power output are quantitatively analyzed under different working conditions.The above research content lays the foundation for the subsequent optimization of system structural parameters and controller parameters.This paper studies the power smoothing control problem of the energy storage hydraulic type wind turbine with the hydraulic energy storage system.In order to improve the smoothness of power output unit,the hydraulic accumulator system is added to the unit,and the PID control algorithm is established by controlling the energy accumulator store realize smooth control of the power.And the principle of energy storage systems were introduced,then the mathematical model of the hydraulic energy storage system and the inherent characteristics of the hydraulic accumulator system is analyzed.Finally,the hydraulic energy storage system alone energy storage and the hydraulic energy storage system combined with wind turbine energy storage are simulated,and the simulation results are compared and analyzed.Finally,the 24 kW hydraulic wind turbine experimental platform was used to verify the speed control strategy before grid connection and the active power control strategy after grid connection.