Research On Resonance Suppression Of Long Pipeline Of Hydraulic Ground Wind Turbine

As an important part of clean energy,wind energy is receiving more and more attention from all over the world.Wind power generation technology is developing towards multipower level,wide application fields and diversified models.As a new type of wind turbine,hydraulic wind turbine has become an important research direction because of its small size,light weight and high power-to-weight ratio.Different from the conventional configuration,the hydraulic ground-based wind turbine puts the quantitative pump in the cabin,sets the variable motor,generator and its corresponding control system at the tower base,realizes the hydraulic transmission between the quantitative pump and the variable motor through long pipeline,which can greatly reduce the installed weight and reduce the difficulty of Engineering installation.However,the long hydraulic pipeline will make the resonance effect more obvious.Under the excitation of random wind,resonance may occur in a wide frequency range,endangering the stability of the structure and affecting the quality of power generation.In this paper,the pressure resonance in the long pipeline of the hydraulic wind turbine is studied.The impedance model of the main transmission system of the long pipeline is established by using the electro-liquid similarity theory.Based on the distributed parameter model of the long pipeline,the pressure transfer function at both ends of the long pipeline is established.The implicit function conditional equation of pressure resonance frequency is obtained by using the pressure transfer function of derivative method.The expression is theoretically analyzed from the angle of pressure wave propagation,and then the expression of resonance peak value is obtained.Based on the conditional equation of resonance frequency,the influence of parameters on pressure resonance frequency is analyzed.Firstly,the sensitivity of parameters to pressure resonance frequency is analyzed for different power levels of wind turbines,and the influence degree of each parameter on resonance frequency is obtained.Secondly,the influence of controllable variable motor displacement and throttle impedance on resonance frequency is analyzed emphatically,and the numerical conditions for the displacement of motor displacement and throttle impedance to offset resonance frequency are obtained.Finally,the sensitivity of the peak value of pressure resonance is analyzed,and the influence of the displacement of variable motor and the impedance of throttle valve on the resonance frequency is studied.According to the above conclusions,an active control method of pressure resonance using motor displacement and throttle valve as control input is proposed.On the one hand,the resonance frequency of pressure resonance deviates from the excitation frequency,on the other hand,the peak value of pressure resonance is reduced.Adjusting the motor displacement and throttle impedance will result in energy loss of the system.Therefore,multi-objective genetic algorithm is used to optimize the motor displacement and throttle impedance by taking pressure fluctuation attenuation and unit energy loss as optimization objective functions,so as to realize the attenuation of pressure fluctuation amplitude in different degrees.Experiments were carried out on the experimental platform of 30 kVA hydraulic wind turbine.The excitation signals were generated in the long pipeline by applying sinusoidal or sweeping frequency signals by variable pump/motor.The amplitude characteristic curve of pressure transfer function was obtained by spectrum analysis of the signals.The correctness was verified by comparison with the theoretical analysis results.