Research On Design And Control Of A 600kW Hydraulic Wind Turbine With An Energy Storage System

The rapid development of wind power industry plays an important role in alleviating the energy crisis,solving environmental pollution problems and promoting the economic development of the world.The traditional wind turbine with gear drive has the disadvantages of high failure rate of gearbox,high cost of converter and high maintenance cost.Compared with the gear transmission,the direct-driven units remove the gear box,but still need huge converters.The hydraulic wind turbine eliminates the gearbox and converter,and it presents unique advantages such as high power density,easy to realize stepless speed regulation and large system stiffness.Therefore,it has become the research hotspot of wind power.Because of the randomness,fluctuation and intermittence of wind energy,the integration of large-scale wind power into the power system will bring tremendous impact on the stable operation of the grid and reduce the power quality,which has become a bottleneck restricting the development of wind power.Therefore,this paper proposes to introduce the large-capacity hydraulic energy storage system into the hydraulic wind turbine to eliminate the adverse effects of wind energy fluctuation on the power grid and power quality,and to realize the efficient storage and utilization of wind energy and high-quality power output,which is of great significance to the development for the new generation wind power.According to the technical parameters and requirements of 600 kW hydraulic wind turbine with an energy storage system,we design the overall scheme and the hydraulic circuit of the unit.Based on the analysis of the structure and working process of the hydraulic wind turbine with an energy storage system,the whole hydraulic system is divided into three basic hydraulic circuits: wind-hydraulic energy storage,hydraulic energy storage generation,storage and generation of wind energy.The mathematical model of the main components of the unit is deduced.By analyzing the corresponding relationship between the mathematical model and the AMESim component library,the simulation models of three basic hydraulic circu its are established.Aiming at the speed control of wind-hydraulic energy storage,a double closed-loop control method of wind turbine speed is proposed,which combines the speed closed-loop of wind turbine with the speed closed loop of main hydraulic motor.This method solves the control problems of wind turbine speed,hydraulic pump speed and wind energy storage under the condition of wind speed fluctuation and accumulator pressure change.Moreover,we analyze and study the changing law of parameters such as the blade tip speed ratio,wind energy utilization coefficient,main hydraulic motor speed,and storage flow rate,etc under the step signal of wind speed and wind wheel speed.As for the control of the basic working circuit of the hydraulic energy sto rage generation,in order to realize the accurate control of motor speed,we study the influence of PID parameters on the anti-disturbance ability of motor speed control.In order to reduce the influence of time-varying nonlinearity of the hydraulic system on the control performance of the system,we present a neural network PID control algorithm for the speed control of the unit.Furthermore,taking the motor start-up process of the basic circuit of hydraulic energy storage generation as the research object,the single neuron PID control simulation is carried out by using the AMESim-MATLAB joint simulation model.The simulation results show that the single neuron PID control has strong robustness and self-adaptability.In order to realize the maximum wind energy absorption and utilization of 600 kW hydraulic wind turbine with an energy storage system,aiming at the realization principle of wind turbine speed control and the main factors affecting wind energy utilization coefficient of wind turbine,we propose a maximum power tracking control method based on the optimal blade tip speed.In addition,based on the automatic charging and discharging characteristics of the accumulator,we propose to decouple the absorbed power of the wind turbine and the output po wer of the generator by using the energy storage system,and realize the automatic compensation of the power difference between them.The simulation results verify the feasibility and effectiveness of the maximum power tracking control method and the autom atic power compensation of the storage system.The experiment platform of 600 kW hydraulic wind turbine with an energy storage system is built.The start-up method and start-up process of wind turbine are put forward.The field test of 100 kW class wind-hydraulic energy conversion is successfully completed.The rationality of the proposed control methods of wind turbine start-up,wind turbine speed and hydraulic motor speed is verified by experiments,which provide a theoretical basis and guidance for the d esign of hydraulic wind turbine with an energy storage system.