兆瓦级并联型风电变流器热负荷平滑控制研究

风电变流器采用并联型结构能增加容量至兆瓦级,因而在风电机组中得到了广泛应用。由于变流器的运行功率随着风速变化,功率半导体器件的工作电流和驱动功率也随着变化,导致其结温波动显著,这将影响器件的寿命,并降低变流器的可靠性,而可靠性是兆瓦级风电变流器的关键性能之一。针对这个问题,本文提出了一种兆瓦级并联型风电变流器的热负荷平滑控制策略以提高变流器的热稳定性。在热负荷平滑控制中,额外的无功功率引入到变流器输出中,然后增加的无功电流能够使得当风速变小时,功率器件的热负荷保持平稳,从而使得其结温趋于更加稳定,生命周期延长,变流器的可靠性提高。最后,搭建了基于Matlab/PLECS的仿真平台,以3 MW并联型风电变流器为算例进行了仿真计算,计算结果表明,在热负荷平滑控制下,当变流器的热负荷变化时,IGBT的结温波动从原来的34℃下降到12℃,验证了该控制方法的有效性。

Thermal Smooth Control Analysis for Megawatt Parallel Wind Power Converter

The wind power converter with parallel structure can increase the capacity to the megawatt level,so it is widely used in the wind turbine. Because of the wind power fluctuation,the current of the power semiconductor device with its drive power is fluctuating largely and rapidly,which will cause a large junction temperature variation,affecting the lifetime of power semiconductors and the reliability of the converter,but the reliability is the key issue for the wind power converter. Aiming at it,the thermal smo-oth control for megawatt parallel wind power converter has been proposed in this paper to improve the converter’s thermal reliability. With the proposed thermal smooth control method,extra reactive power is introduced to the converter,and the reactive current smooth the thermal stresses of power semiconductor devices when the wind speed slow down. So the junction temperature variation become smaller,and the lif-etime power semiconductor devices become longer,and the wind power converter’s reliability improved. Finally,a simulation platform based on MATLAB/PLECS is built,and some calculations have been done with the 3MW parallel wind power converter. The simulation results show that when the load of the converter changes,the temperature fluctuation of IGBT is changed from 34℃to 12℃.