Research On Power Smoothing Control Of Hydraulic Type Wind Turbine

Following the shortage of traditional fossil energy sources, energy supply and environmental protection were focused on by nations. As a clean and pollution-free and sustainable use of renewable energy, it is significant for wind power to adjust energy structure, save resources, protect the ecological environment and promote sustainable economic development. And it is very important for wind power to adjust the energy structure of nation.It is easy for hydraulic wind turbine to reduce cabin weight effectively, improve power quality and reduce the impact on the grid. And there are some merits for hydraulic wind turbine: small harmonics and strong LVRT(low voltage ride through) capability and adjustable power factor according to gird demand. Because the wind speed is fluctuant and the parameters of system will be changed according to different conditions, so smoothing power output of hydraulic wind turbine is required in different conditions to improve power quality.In this paper, hydraulic wind turbine is researched with theoretical analysis and experimental research method. Based on fix-displacement pumps – variable displacement motor closed system characteristics, hydraulic pitch angel with valve-controlled motor system characteristics, and hydraulic system power transmission characteristics, power tracking and smoothing control in low wind speed condition, power moothing control with pitch angel control in high wind speed condition, and power smoothing output with hydraulic power system characteristics are researched. The research has great theoretical significance and application valueMulti-objective control of tracking power and power smoothing output in low wind condition is studied. According to inverse system design principles of nonlinear system control, equation of state space is established; the multi-objective controller of power tracking and power smoothing is designed based on torque control, and the simulation is studied.Power smoothing output control in high wind speed condition is studied. The model of hydraulic valve-control motor pitch angel control system is established. A fuzzy PID pitch angle control method is proposed to achieve power smoothing control in high wind condition, and the simulation is studied.The power output influence of hydraulic wind turbine by hydraulic system charateristics is analyzed. The pipe line model of hydraulic wind turbine is setup, the power output fluctance influence by flow pulsation of the pump components and motor components is considered, and the power output fluctance influence by fluid density, kinematic viscosity of the oil, the oil bulk modulus of oil are considered, and the simulation is studed.The power smoothing control experiment platform of 30 k VA hydraulic wind turbine is setup, through experiment the multi-objective control method of power tracking and power smoothing control in low wind speed condition and the power smoothing control method of pitch angle control in high wind speed condition are verified. And power output influence by the pipe length characteristic is analysised.