Research On Control Strategy Of Dual PWM Converter Pumping Water System For Off Grid Direct Drive Wind Power Generation

With the implementation of the national "14th Five-Year plan",the wind power industry will usher in rapid development.In order to improve the utilization rate of grassland,it is necessary to irrigate grassland.Grassland is generally located in remote areas,and the cost of using power grid to provide water for irrigation is high.However,Inner Mongolia is rich in wind power resources.Therefore,the development of off grid wind power generation pumping water irrigation system to improve the utilization rate of grassland is not only in line with the national planning for the development of wind power industry,but also can reduce the cost of Grassland Irrigation.In this project,the pumping water system of off grid direct drive wind power generation is taken as the research object,and the mathematical model of the system is established.On this basis,the three parts of the system,including the side converter control,the load side converter control and the energy coordination control of the dual PWM pumping water system,are studied in detail.The main research work is as follows:1)Research on the control strategy of the side to side converter for the off grid direct drive permanent magnet wind power generation system: first of all,to meet the demand of off grid direct drive wind power,a control strategy using DC side converter to control DC side voltage stability is proposed;through the simplification of the system structure,the PI control parameters of the current loop and the voltage loop are designed,by analyzing the vector diagram of the permanent magnet synchronous motor,two kinds of vector control strategies,namely "motor output voltage control" and "new unit power factor control",are designed;finally,the SVPWM algorithm is used to verify the correctness and feasibility of the proposed control strategy in Simulink.2)Study on the control strategy of load side converter of off grid asynchronous induction motor pumping water system: First,the direct torque control strategy of the 24 sector asynchronous motor is designed by introducing the three position hysteresis controller of flux linkage,and the stator flux observer is improved;Secondly,by analyzing the characteristics of water pump and water pipeline,a direct torque control strategy of asynchronous induction motor is designed to control the shaft power of water pump;finally,the correctness of flux observer,24 sector direct torque control strategy and the feasibility of controlling pump shaft power are verified in Simulink.3)Research on energy coordinated control strategy of Dual PWM water pump system:by analyzing the energy flow model of Dual PWM water pump system,an energy coordinated control strategy composed of asynchronous motor power outer loop power setting,variable pitch control and system start-up control is designed to ensure the smooth start-up and stable operation of Dual PWM water pump system.The rationality and feasibility of the design are verified in Simulink.