The Research On The The Direct Torque Control Of Direct-driven Wind Power Converter System

In the recent times of energy shortage and environmental pollution increasinglyserious, as a renewable green energy, the development and utilization of wind powerhas great significance. In the wind power generation system of high power especiallyMW level, permanent magnet synchronous wind power system compared with thetraditional double fed wind system omits the slip ring and carbon brush, without theneed for a rotor excitation, and saves the transmission gear box, thereby having goodlow-speed performance, maintenance simple control, high power generation efficiency,system reliability and other advantages. With the increasing capacity of wind turbines,improving the units’ operational efficiency， maximizing the use of wind energy andseeking a good control method has become an important part of the wind powertechnology research.With the operation and control of Permanent-magnet Direct-driven wind powerconverter as the research subject,studying the direct torque control method, this thesismade complete study by simulation and experiment.First, the article introduced the direct driving wind power converter system andthe PWM converter’s working principle, derived in detail the mathematical model ofthe permanent magnet synchronous motor in the three-phase stationary coordinatesystem, the two-phase stationary coordinate system and the two-phase synchronousrotating coordinate system, laid the foundation for subsequent research. Then, Thepaper describes the basic principle of direct torque control, applied the direct torquecontrol technology to the control of permanent magnet synchronous wind turbine,in-depth analysis of the theory of direct torque control for generator control principle,gave the voltage, flux and torque expression of the direct torque control system underthe stator flux orientation,solved the problems of the switching voltage vector tablestructure and the torque and flux given values based on different control objectivesand other issues. The thesis gave the machine side direct torque control scheme ofdirect drive wind power generation system, set up the control block diagram of thesystem, detailed description of the direct torque control of working process, andpointed out the advantages of using direct torque control were eliminating thecomplex coordinate transformation, calculation of complicated issues, and the torque,speed response faster and faster to achieve maximum wind energy capture, put forward corresponding improvement measures about the shortcomings of theconventional direct torque control. In order to improve the quality of power, thispaper applied the idea of fuzzy control to the direct torque control, designed a fuzzycontroller in place of flux and torque hysteresis comparator of the traditional directtorque control. Flux error, torque error, the stator flux angle were taken as inputvariables, the inverter switching state as output variables. This paper established thewind turbine model, space vector modulation model, the flux and the magnetic fluxangle calculation model, magnetic chain regulator and torque regulator model and soon according to the derivation of the mathematical model, in the Matlab/Simulink2009simulation software. The vector control, direct torque control and fuzzydirect torque control simulation of direct driving wind power systems machine sideconverter was carried out. The experimental results verified the feasibility andvalidity of the used method.