Research And Design Of The Grid Converter In The Direct-drive Wind Power System

Nowadays, the stock of fossil energy is less and less in human society. Findingrenewable energy which can stead of the fossil energy is the most important thing forthe survival and development of mankind. Many countries consider to use the windpower because of its renewable.At the same time, the wind power is a clean energysource which plays a significant role on the protection of the worldenvironment.Therefore, it is very important to the researchf the converter of the windelectricity generation system.This article which takes the three-phase voltage PWM rectifier as the researchobject of grid converter, establishes of the mathematics model of the three phase VSRthrough analysising the circuit of three-phase VSR in the three phase stationarycoordinate and then changes the mathematical model to the one in the synchronouslyrotating coordinate through the three-phase to two-phase transformation and thetwo-phase stationary rotation transformation. This paper also analyses the controlstrategies and the design method of the controller based on voltage oriented, directpower control and the virtual flux. This paper focuses on the direct power control andget the mathematical model of direct power control by combining the mathematicalmodel of the three-phase VSR in dq coordinates with the instantaneous reactive powertheory and then designs the hysteresis controller. In order to solve the shortcomingthat the switching frequency of direct power control is not fixed,this paper designsthe control strategy with fixed switching frequency by combining the direct powercontrol with the voltage space vector modulation.the power ring is improved,thispaper uses control strategy combining the fuzzy control with the discrete space vectormodulation(DSVM) which can give more choices when the voltage vector iscomposed.As a result, the system get the better dynamic performance and can followthe given faster than before. The simulation results show that the direct power controlof the three phase VSR can make the output well follow the given and the system canwork as a rectifier or inverter by using the hysteresis controller and fixed switchingfrequency controller while a better robustness of the system with sliding modecontroller and a better dynamic performance with the controller based onDSVM.Finally, this article designs the three-phase VSR system which uses theTMS320F2812product by Texas Instruments in America as the main controller.Then this paper analyzes parameters of the main circuit devices of the system. andresearches the design principles of the AC inductance and DC capacitor.At the sametime,the article designs the control circuit of the the three-phase VSR system, map thePCB circuit diagram and write the control software program in the CCS3.3environment.