Research On Improving Reliability Of Twelve Phase Permanent Magnet Wind Turbine

Due to the abundant offshore wind resources,the Chinese government is paying more and more attention to the development of offshore wind power.Since the 13 th Five-Year Plan,my country's offshore wind power has developed rapidly and the scale of installed capacity has continued to increase.However,due to the harsh offshore climate environment,there are problems such as high equipment cost,maintenance difficulties,and low reliability,which severely restrict the development of offshore wind power.This article focuses on the reliability of 12-phase permanent magnet wind turbines in offshore wind power generation systems.The research content is as follows:First of all,to address the problem of increased coupling between the stators of the twelve-phase permanent magnet wind turbine due to the increase in the number of phases,under the condition of non-zero mutual coupling between the four stators of the twelve-phase permanent magnet wind turbine,the generator electrical Phase distribution diagram,detailed generator mathematical model is derived,combined with Park transformation,the complete voltage equation of twelve-phase wind generator is obtained,classical vector control design is adopted,q and d variables are decoupled to obtain the Laplace domain Using the internal model control(IMC)design method to design the stator controller,design the current regulator based on the open-loop and closed-loop frequency response of the generator of the multivariable system,build the MATLAB/Simulink simulation model and verify it by experiment The designed current regulator can track the current set point and reduce the coupling effect between the stators.Secondly,in order to improve the fault tolerance performance of the twelve-phase permanent magnet wind turbine,the twelve-phase permanent magnet wind turbine is combined with a modular multilevel converter(Modular Multilevel Converter,MMC)to establish a combined topology and deduced The mathematical model in the dq rotating coordinate system obtains the equivalent circuits of generator-side and grid-side converters,and proposes fault-tolerant control strategies for power module redundancy switching and common-mode voltage segmented injection for generator-side and grid-side faults.In order to solve the problem that the modular multilevel converter is difficult to detect and locate the fault accurately and quickly,a fault diagnosis method based on the improved sliding mode observer(SMO)was proposed.Through MATLAB/Simulink The simulation verifies the effectiveness of the above method.Finally,in order to solve the problem of terminal overvoltage caused by PWM converter pulse waves of permanent magnet wind turbines transmitted through long cables,a long cable transmission equivalent circuit model was established,the mechanism of overvoltage generation was analyzed,the transfer function was introduced,and the filter parameters were optimized.The parameters of the new filter are designed.Based on the common mode current attenuation method,a new RLC-plus-C passive filter and its design method are proposed.On this basis,a complete calculation method is designed in Matlab for the value of inductance.Through MATLAB/Simulink simulation analysis,the new filter further suppresses the overvoltage at the terminal,while significantly reducing the bearing current and improving the reliability of the permanent magnet wind turbine.