中文摘要：

风电变流器的可靠运行是风能转换系统中的重要关注对象。然而现有文献评估器件结温对变流器可靠性的影响时，却没有重视结温波动的影响，以致往往高估了风电变流器的可靠性。该文基于永磁同步风力发电机工作的恶劣环境，分别从切入运行风速、额定风速、切除停机风速、开关频率及功率因数的变化，造成变流器中器件结温幅值及其波动差别的角度出发，利用Coffin．Manson器件可靠性评估模型，评估网侧变流器可靠性的差异。以1Mw风机结合实际风速数据为例进行分析论证，结果验证了理论分析的正确性。统计数据结果表明，额定风速及开关频率的变化对变流器可靠性的影响比较大。为了实现变流器的高可靠运行，风机宜在低风速切入运行，尽可能高的风速切除停机。

英文摘要：

The reliability of converters is significant for wind energy conversion systems. However, the effect of junction temperature fluctuation is not valued by present papers when evaluating reliability of converters in wind turbines based on junction temperature of devices. As a result, it is often overestimated. Based on bad operating environments of permanent magnetism synchronous generators （PMSGs）, the change of the cutting in wind speed, the rated wind speed, the cutting out wind speed, the switching frequency and the power factor, leading to the difference of junction temperature and its＇ fluctuation of devices, was considered in the paper, and the Coffin-Manson reliability evaluation model was used to evaluate the difference of reliability of converters in the grid side. Then, consideried the actual wind speed, a 1 MW wind turbine was illustrated. The test results verified the correctness of the theoretical analysis. The result indicates that the change of rated wind speed and switching frequency has a significant effect on converters＇ reliability. To get high reliability of converters, it is suggested that the wind turbine would better cut in with a low wind speed and cut out with a high wind speed possible.