Due to the diversity of distributed generation sources, microgrid inverters work under complex and changeable conditions. The core device of inverters, an insulated gate bipolar transistor (IGBT), bears a large amount of thermal stress impact, so its reliability is related to the stable operation of the microgrid. The effect of the IGBT aging process cannot be considered adequately with the existing reliability evaluation methods, which have not yet reached the requirements of online evaluation. This paper proposes a fusion algorithm for online reliability evaluation of microgrid inverter IGBT, which combines condition monitoring and reliability evaluation. Firstly, based on the microgrid inverter topology and IGBT characteristics, an electrothermal coupling model is established to obtain junction temperature data. Secondly, the segmented long short-term memory (LSTM) algorithm is studied, which can accurately predict the aging process of the IGBT and judge the aging state via the limited monitoring data. Then, the parameters of the electrothermal coupling model are corrected according to the aging process. Besides, the fusion algorithm is applied to the practical case. Finally, the data comparison verifies the feasibility of the fusion algorithm, whose cumulative damage degree and estimated life error are 5.10% and 5.83%, respectively.

中文翻译：

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微电网逆变器IGBT在线可靠性评估的融合算法

由于分布式发电资源的多样性，微电网逆变器可在复杂多变的条件下工作。逆变器的核心器件绝缘栅双极型晶体管（IGBT）承受大量的热应力影响，因此其可靠性与微电网的稳定运行有关。现有的可靠性评估方法无法充分考虑IGBT老化过程的影响，而这些评估方法尚未达到在线评估的要求。提出一种融合状态监测和可靠性评估的微电网逆变器IGBT在线可靠性评估融合算法。首先，基于微电网逆变器拓扑和IGBT特性，建立电热耦合模型以获得结温数据。其次，研究了分段长短期记忆（LSTM）算法，该算法可以准确预测IGBT的老化过程，并通过有限的监测数据判断老化状态。然后，根据时效过程校正电热耦合模型的参数。此外，将融合算法应用于实际案例。最后，数据比较验证了融合算法的可行性，该融合算法的累积损伤度和估计寿命误差分别为5.10％和5.83％。