大容量风电变流器的设计寿命决定了其可靠性,非常关键,而变流器中功率半导体器件的结温将随着风速变化,即随变流器运行功率的变化而波动,这将增加器件的失效率,从而影响到变流器的可靠性.针对这个问题,提出了一种基于无功环流的风电变流器热负荷优化控制策略,首先以双馈风电机组作为研究对象,对其变流器转子侧和网侧的无功环流运行边界范围进行了计算,然后分析了无功环流对变流器中各个功率器件的电流和热负荷分布的影响,从而设计了将额外的无功功率注入以在风速变化时保持功率器件热稳定的优化控制方法.最后,基于Matlab/Plecs的仿真平台建立了风电机组仿真模型并进行了对比计算.结果表明,风速变化时新控制方法使变流器的功率器件最大结温波动较传统方法减小了4℃,从而验证了其有效性.%The design service life of the large capacity of wind power converter determines its reliability which is very important. The junction temperature of the power semiconductor devices in converters will fluctuate when the power point of the converter transforms with the change of the wind speed ,and this will increase the failure rate of the device,which affects the reliability of the converter. To solve it,a thermal behavior optimal control strategy for wind power converter with reactive power circulation was proposed. At first ,aiming at the doubly fed induction generators wind turbines,the reactive power circulation operation boundary ranges at both the rotor side and grid side of the converter were calculated ,then the influences of the current and the thermal stresses in power semiconductor devices by reactive power circulation were analyzed. Therefore ,the optimal controller which add extra reactive power inject to the converter to maintain the power device thermal stability when wind speed changed was designed. Finally ,the simulation model which was based on Matlab/Pecs platform was established ,and some calculations were done to compare the new method and the conventional one. The results show that the new control method makes the maximum junction temperature fluctuation of the power device in converter is 4 degrees lower than the traditional method with the same change of the wind speed ,and the effectiveness of the new controller is verified.
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