Partial discharges (PD) are the ‘cancer’ of electrical insulation. Insulation design and mitigation of PD-induced degradation should be based on good knowledge of PD phenomena. In that regard, a significant body of knowledge has been built up from concerted research across the world in past decades and on various aspects of PD phenomena under various conditions. However, the work is far from being complete as new challenges arise. One such challenge is that electric power equipment insulation is becoming more exposed to non-power frequency voltages. Examples are the proliferation of invertor-based grid-tied renewable energy sources and other technologies such as high-frequency power electronic transformers. Questions that are driving continued research in this regard include the reasons for lack of consensus on the findings on how PD characteristics respond to variations in the voltage frequency. This paper presents results of how residual charge influences PD characteristics' response to voltage frequency changes from 1 to 200 Hz. The study approach is implementing the extended 3-capacitor PD model in MATLAB^® Simulink^® and validating the findings using the relevant experimental results that are available in literature. The PD type studied is that of an air cavity encapsulated in a polyethylene dielectric. Highlights of the findings are that the extent of the influence of residual charge on PD characteristics depends on the relative magnitude of the residual charge as well as the voltage frequency. The relationships however exhibit non-monotonous trends. Such results further confirm similar findings and conclusions by other researchers and could be signalling the establishment of a more solid knowledge base for design of insulations that operate at non-power frequencies.

中文翻译：

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残余电荷对局部放电对变化的亚kHz电压频率的响应的影响

局部放电 (PD) 是电气绝缘的“癌症”。绝缘设计和缓解局部放电引起的退化应基于对局部放电现象的充分了解。在这方面，过去几十年来，世界各地对各种条件下的局部放电现象的各个方面的协调一致的研究已经积累了大量的知识。然而，随着新挑战的出现，这项工作还远未完成。其中一项挑战是电力设备绝缘越来越容易受到非工频电压的影响。例如，基于逆变器的并网可再生能源和高频电力电子变压器等其他技术的激增。推动这方面持续研究的问题包括，对于局放特性如何响应电压频率变化的研究结果缺乏共识。本文介绍了残余电荷如何影响局部放电特性对 1 至 200 Hz 电压频率变化的响应的结果。研究方法是在 MATLAB 中实现扩展的 3 电容器 PD 模型^® Simulink ^®并使用文献中提供的相关实验结果验证研究结果。研究的局部放电类型是封装在聚乙烯电介质中的空气腔。研究结果的要点是，残余电荷对局部放电特性的影响程度取决于残余电荷的相对大小以及电压频率。然而，这些关系表现出非单调的趋势。这些结果进一步证实了其他研究人员的类似发现和结论，并可能标志着为非电源频率下工作的绝缘设计建立了更坚实的知识库。