PV inverters can provide reactive power while generating active power. An ongoing microgrid implementation at Duke Energy actively engages non-utility PVs to generate/absorb reactive power in support of ancillary services to increase microgrid resiliency during extreme events. PV systems are requested to provide reactive power support: 1) in response to grid voltage variation to better regulate the local voltage; or 2) in response to utility incentives, such as following Transactive Energy System (TES) incentives. However, providing ancillary services might shorten the lifetime expectation of PV inverter semiconductors. This paper summarizes the potential impacts on a PV inverter semiconductor's lifetime when providing ancillary services. The analysis presented in this research work shows that providing reactive power support will increase the mean junction temperature and the junction temperature variation of the inverter diodes. This increased junction temperature will eventually lead to shorter diode lifetime. The lifetime estimation of semiconductors is briefly reviewed. The power losses of PV inverter semiconductors are derived as a support analysis to the junction temperature calculation. In addition, the impact of the filtering inductor on the semiconductor current distribution is discussed. The theoretical analysis presented in this research work is supported by simulation results.

中文翻译：

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用于辅助服务的光伏逆变器半导体的老化效应分析

光伏逆变器可以在产生有功功率的同时提供无功功率。杜克能源公司正在实施的微电网正在积极参与非公用事业光伏发电，以产生/吸收无功功率，以支持辅助服务，从而在极端事件中提高微电网的弹性。要求光伏系统提供无功功率支持：1）响应电网电压变化以更好地调节局部电压；或2）响应公用事业激励措施，例如遵循无源能源系统（TES）激励措施。但是，提供辅助服务可能会缩短PV逆变器半导体的使用寿命。本文总结了提供辅助服务时对光伏逆变器半导体寿命的潜在影响。这项研究工作中进行的分析表明，提供无功功率支持将增加逆变器二极管的平均结温和结温变化。结温的升高最终将导致二极管寿命缩短。简要回顾了半导体的寿命估算。导出PV逆变器半导体的功率损耗，作为对结温计算的支持分析。此外，讨论了滤波电感对半导体电流分布的影响。仿真结果支持了本研究工作中提出的理论分析。简要回顾了半导体的寿命估算。导出PV逆变器半导体的功率损耗，作为对结温计算的支持分析。此外，讨论了滤波电感对半导体电流分布的影响。仿真结果支持了本研究工作中提出的理论分析。简要回顾了半导体的寿命估算。导出PV逆变器半导体的功率损耗，作为对结温计算的支持分析。此外，讨论了滤波电感对半导体电流分布的影响。仿真结果支持了本研究工作中提出的理论分析。