Fundamental Investigations on the Aging of Insulating Materials under Harmonic Distorted Voltages

越来越多的可再生能源纳入电力系统导致越来越多的使用电力电子。由于其高开关频率，现代电力电子系统节省空间，高效，并允许灵活的发电操作。以固态变压器为例，由于其结构紧凑，通常应用于中压电网、交通运输和海上电站。然而，电力电子器件的高开关频率会产生谐波，其频率高于电网频率（50hz / 60hz），导致电压叠加，从而引起电压畸变。电压畸变会影响电气设备中应用的绝缘材料的老化，如环氧树脂和硅树脂。除了由于介质损耗增加而引起额外的散热量外，电压畸变还会影响电气和局部放电老化过程。本项目的目的是研究在非标准化扭曲电压下，绝缘材料的电气和局部放电老化过程。畸变电压对耐压性能的影响有待确定。测量是在固体绝缘材料上进行的，如环氧树脂和硅树脂，这些材料除其他外，用于电力电子元件和电力电子控制设备中。所研究的电压波形包括典型的电网电压畸变以及功率变换器中可能出现的高频叠加电压。在此基础上，提出了一种包含畸变电压引起的附加应力的先进的现象老化模型。Zittau应用科学大学/Görlitz和德累斯顿工业大学之间的合作可以结合各自在扭曲电压以及电气和局部放电老化方面的专业知识。这些研究有助于更好地理解固体绝缘材料的老化过程。具体来说，先进的老化模型也考虑了电压畸变引起的额外应力，将使最先进和未来的电气设备在可靠性方面得到改进。

The increasing incorporation of renewable energy sources into the electric power systems results in an increasing usage of power electronics. Due to their high switching frequencies, modern power electronics systems are space-saving, efficient and allow flexible operation in energy generation. An example is the solid state transformer, which is generally applied in medium voltage electric grids, transportation and offshore plants due to its compactness. However, the high switching frequencies of power electronics can induce harmonics, which possess frequencies higher than the grid frequency (50 Hz/60 Hz), resulting in a superimposed voltage and thus cause voltage distortion. Voltage distortion can affect the aging of insulation materials applied in electrical equipment, such as epoxy resin and silicone. Other than provoking additional dissipated heat due to increased dielectric loss, voltage distortion can also influence aging processes in terms of electrical and partial discharge aging. The aim of this project is to investigate the electrical and partial discharge aging processes of the insulation materials when stressed with a non-standardised distorted voltage. The influence of the distorted voltage on the voltage endurance behaviour are to be determined. The measurements are conducted on solid insulation materials such as epoxy resin and silicone, which are, amongst others, used in power electronics components and found in power electronics controlled equipment. The investigated voltage waveforms include typical grid voltage distortion as well as superimposed voltages with higher frequencies, which can occur in power converters. Based on the measured results, an advanced phenomenological aging model incorporating the additional stress caused by distorted voltages will be developed. The cooperation between University of Applied Sciences Zittau/Görlitz and TU Dresden allows the combination of the respective expertise regarding distorted voltages as well as electrical and partial discharge aging. The investigations contribute to a better understanding of aging processes in solid insulation materials. Specifically, the advanced aging model, which also takes the additional stress due to distorted voltages into account, will enable the improvement of state-of-the-art and future electrical equipment with to regard the reliability.