Study On Permanent Magnet Direct Drive Wind Turbine Generation Based On Power Coordinated Control

With the increasingly serious problem of global resource people begin to paymore attention on green renewable energy. As one kind of extensive resourcesand clean energy the wind power develops fast. Permanent magnet direct-drivewind power system capacity is still relatively small at this stage. But it has highconversion efficiency, high reliability and flexible ability to control and is verysuitable for our country that has a large number of low-speed wind farms.Therefore, research on permanent magnet direct drive wind power system has avery important significance. So this paper mainly focus on a study of the controlstrategy.First, this paper describes how to build a math mathematic model of thepermanent magnet direct-drive wind power system by studying the workingprinciple and operating characteristics of it. And this model includes five partsthat looks like permanent magnet synchronous generator and PWM (Pulse-WidthModulation) converters. For using the vector control strategy, focusing on themathematical model of PWM converter and permanent magnet synchronousmotors were analyzed by transforming the stationary coordinate system of abcto dq rotating coordinate system.Then the maximum wind tracking were analyzed. And the motor side chosethe method of the best tip speed ratio as the best ways. In order to achieve thespecific the PWM converter of motor side uses zero d-axis current vector controlstrategy while the speed feedback is the outer ring. In order to stabilize the gridside converter DC side and regulate the use of active and reactive power grid voltage oriented vector control and voltage loop control strategy are used. Butwhen the wind mutation happened the DC voltage will fluctuate because of theinertia effection of the capacitor. In order to eliminate this kind of situationpower coordinating control strategy is proposed. The upcoming pre-motor powerfed to the grid side converter and the rate of change of the motor side converterpower restrictions would be amended to eliminate the capacitive inertial effectsand stable DC voltage and the role of the grid of the output current.Finally PSCAD/EMTDC software is used as a platform to build a simulationmodel of1.5MW direct-drive permanent magnet wind power system. By usingthe model experiment verifies the correctness of the strategy of the motor sideand the grid side control method.