Study On Mathematical Model And Performances Of Integrated Direct-Drive Permanent Magnt Wind Turbine Generator System

The direct-drive permanent magnet wind turbine generator system has been used extensively in wind farms due to its superior integration performances. The integration stability has become a vital factor of the operating safety of the integrated wind turbine generator system, in fact it has aroused high attention of the majority wind power researchers. The integration performances of the direct-drive permanent magnet wind turbine generator system are mainly influenced by sudden changes of the wind speed and grid failures, relating to a complex set of subjects including aerodynamics, structural dynamics, electromechanics, power electronics, automation and control. As a result, intense researches on the integration performances of the direct-drive permanent magnet wind turbine generator system have theoretical significance.So far, rarely has any mathematical model of the direct-drive permanent magnet wind turbine generator system been reported in the literature that has an overall consideration on the sudden changes of wind speed and grid failures including the wind speed, the direct-drive permanent magnet wind turbine generator system, the rectifier and the inverter; neither does researches on the spot performance tests of the wind turbine generator system. Filling the blank in these two areas is the aim of this dissertation. Innovative contents of this paper can be summarized as follows:In this dissertation the direct-drive permanent magnet wind turbine generator system was taken as the study object and its structural dynamics equations were established; the vortex theory was used to establish the dynamic mathematical model of the direct-drive permanent magnet wind turbine generator system. These were the foundations on which the basic equations describing the three-dimensional wind farm were established with the computational fluid dynamics theory, and then the computing space of the three-dimensional wind farm was built, the Delaunay method and gradient perpendicular method were used to achieve the non-structural mesh of the computing space and draw the three-dimensional terrain of the wind farm, respectively; the structural and aerodynamic performances of the three-dimensional wind turbine generator system were solved by establishing the three-dimensional simulation model of the wind turbine generator system completely, defining the boundary conditions and the dynamic wind speed and wind direction of the wind farm. The structural and aerodynamic performance curves were obtained and the results had shown the correctness of the theory.On the basis of the accomplished simulation on the aerodynamic performances of the wind turbine generator system, this paper had deduced the balance equations of the power and torque. The coordinate transformation of the converter between the three-phase coordinate system and two-phase coordinate system was achieved to build the mathematical models of the turbine-side rectifier and the grid-side inverter; finally the mathematical model of the direct-drive permanent magnet wind turbine generator system was accomplished by combining mathematical models of the wind dynamic, the wind turbine generator system and the converters; the bilateral power feed-forward control strategy was found based on the power balance theory of the direct-drive permanent magnet wind turbine generator system.On the foundations of the established mathematical models of the wind dynamic and direct-drive permanent magnet wind turbine generator system, the there-dimensional aerodynamic simulation environment of the latter was built in Structure and air power link solving environment, the mathematical model of the latter was built in Unit mathematical model environment and the control strategy and the grid voltage drop regulation was achieved in Power system solve the environment. Simulation researches on the operating control strategies of the integrated direct-drive permanent magnet wind turbine generator system under three modes including normal condition, sudden changes of wind speed on the wind wheel side and grid voltage drop faults were accomplished by the combination use of the three software, the influences of different disturbances on the current components, rotor speed, torque, power, voltage, DC voltage were studied. The simulation results had verified the mathematical models of the wind dynamic and the wind turbine generator system.Further experimental verifications on the established mathematical model and research results of the direct-drive permanent magnet wind turbine generator system had been achieved. Two modes including the single-phase fault and three-phase fault were used to verify the integration operation. The influences of grid faults on the current component and power of the wind turbine generator system were tested. Research results had shown the validity of the mathematical model of the direct-drive permanent magnet wind turbine generator system established as well as the satisfiability of the control strategy for the operation of the integrated wind turbine generator system in this paper.