Nath Debasish, Yang Qichen, Montanari Giancarlo, Yin Weijun, Xiong Han, Younsi Karim
CAPS, Florida State University, Tallahassee, FL 32310, USA.
GE Research, Niskayuna, NY 12309, USA.
Materials (Basel). 2023 Jan 20;16(3):989. doi: 10.3390/ma16030989.
In the design of MV AC and DC spacers, the predominant factors are surface and interface conditions. Design is generally carried out on specifications and standards which are based on long-term experience and lab testing. However, the diffusion of power electronics with a trend to increase electric field, switching frequency, and rise time to achieve higher power density calls for an innovative, global approach to optimized insulation system design. A new methodology, based on field simulation, discharge modeling, and partial discharge inception measurements, called the three-leg approach, can form the basis to optimize insulation design for any type of supply voltage waveform. This paper focuses on the influence of the type of electrode on the inception and phenomenology of surface discharges and, as a consequence, on the interpretation of the results used for application of the three-leg approach. It is demonstrated that a typical electrode system used for insulating material testing can generate both gas and surface discharges at the triple point, when the electrodes have a smooth profile that is used to avoid corona or flashover. Hence, testing partial discharge may not provide a straightforward indication of the surface discharge inception and, thus, be partially misleading for insulation design. Another takeover is that such analysis must benefit from PD testing tools endowed with analytics able to provide automatic identification of the type of defect generating PD, i.e., internal, surface, and corona, since design and remedy actions can be taken, and adequate insulating materials developed, only knowing the type of source generating PD. Hence, testing partial discharge may not provide a straightforward indication of surface discharge inception and, thus, be partially misleading for insulation design. In addition to the importance of the three-leg approach to favor reliable and optimized design of insulation systems, there is a clear need to have a PD testing tool endowed with analytics. It should preferably be able to provide automatic identification of the type of defect generating PD, i.e., internal, surface, and corona.
在中压交流和直流间隔物的设计中，主要因素是表面和界面条件。设计通常依据基于长期经验和实验室测试的规范和标准来进行。然而，随着电力电子技术的发展，为了实现更高的功率密度，电场、开关频率和上升时间有增加的趋势，这就需要一种创新的、全面的方法来优化绝缘系统设计。一种基于场模拟、放电建模和局部放电起始测量的新方法，即三支柱方法，可以为优化任何类型电源电压波形的绝缘设计奠定基础。本文重点关注电极类型对表面放电起始和现象学的影响，进而关注用于三支柱方法应用的结果解释。结果表明，用于绝缘材料测试的典型电极系统在三相点处既能产生气体放电也能产生表面放电，此时电极具有用于避免电晕或闪络的光滑外形。因此，测试局部放电可能无法直接表明表面放电的起始，从而在绝缘设计方面会产生部分误导。另一个要点是，这种分析必须借助具备能够自动识别产生局部放电的缺陷类型（即内部、表面和电晕）的分析功能的局部放电测试工具，因为只有知道产生局部放电的源的类型，才能采取设计和补救措施，并开发出合适的绝缘材料。因此，测试局部放电可能无法直接表明表面放电的起始，从而在绝缘设计方面会产生部分误导。除了三支柱方法对支持可靠且优化的绝缘系统设计的重要性之外，显然还需要一种具备分析功能的局部放电测试工具。它最好能够自动识别产生局部放电的缺陷类型，即内部、表面和电晕。
