考虑基频/低频结温影响的光伏逆变器寿命评估方法

结温波动是光伏逆变器IGBT寿命评估精度的重要影响因素之一. 提出了考虑基频/低频结温影响的光伏逆变器寿命评估方法，首先，将结温剖面按不同时间尺度进行划分，对比分析了基频结温和低频结温的物理特性. 其次，扩大IGBT寿命评估过程中结温波动频率计算范围，建立了相应的光伏逆变器IGBT电热模型、寿命模型， 定量分析了基频结温、低频结温对光伏逆变器寿命评估的影响. 最后，以不同纬度地区为例，评估了不同任务剖面和不同采样周期下光伏逆变器的寿命损伤. 结果表明，综合考虑基频结温、低频结温对光伏逆变器寿命评估的影响，可有效提高光伏逆变器寿命评估的精度，有助于指导光伏逆变器的运行维护，降低非计划停机造成的经济损失.

Lifetime Evaluation Method of PV Inverter Considering the Influence of Fundamental Frequency/Low Frequency Junction Temperature

IGBT junction temperature fluctuation is one of the important factors affecting the accuracy of IGBT life evaluation of photovoltaic inverters. This paper proposes a lifetime evaluation method for photovoltaic inverters that considers the influence of fundamental frequency/low frequency junction temperature. Firstly, the junction temperature profile is divided into different time scales. The physical characteristics of the fundamental frequency junction temperature and the low frequency junction temperature were compared and analyzed. Secondly, the calculation range of the junction temperature fluctuation frequency in the IGBT lifetime evaluation process was expanded, and the corresponding photovoltaic inverter IGBT electro-thermal model and lifetime model were established to quantitatively analyze the influence of fundamental frequency/low frequency junction temperature on the lifetime evaluation of photovoltaic inverters. Finally, taking different latitude regions as examples, the life damage of photovoltaic inverters under different mission profiles and different sampling periods is evaluated. The results show that the method comprehensively considering the influence of fundamental frequency/low frequency junction temperature can effectively improve the accuracy of lifetime evaluation of photovoltaic inverters, which is helpful to guide the operation and maintenance of photovoltaic inverters, and reduce economic losses caused by unplanned shutdowns.