Development of a generic physical model for breakdown and withstand voltages of air-gap insulated configurations in dependence of the atmospheric conditions

在供电系统中，设备的绝缘受到雷击和开关的冲击。适当的绝缘配合和尺寸确定需要知道正确的击穿电压，以避免介质击穿造成的损害。特别是对于气隙绝缘设备，绝缘强度在很大程度上取决于大气环境条件。而主要的环境参数温度、空气湿度、空气压力和空气电导率--以及击穿电压--取决于装置的地理位置。目前对长气隙配置中的击穿电压和耐压的大气校正方法在用于校正不寻常或非典型大气条件(即高于2000 ma.s.l的高度)时，与测量数据相比显示出偏差。相应的标准IEC 60060和IEC 60071显示出不一致，尽管这两个标准都是基于相同的测量和经验模型。世界范围内对这一不足的讨论导致设立了几个工作组，但到目前为止还没有找到解决办法(IEC JWG 42/22；CIGRE WG D1.50)。因此，在上述工作组的支持下，这项研究项目的目的是为深入解决问题奠定必要的基础。主要目标是建立一个普遍有效的击穿过程物理模型，该模型依赖于大气参数，并与不同的结构和电压形式有关。拟议的研究基于最近的知识，即气隙绝缘中的任何击穿过程都包括子过程流光和引线。虽然它们的物理特性似乎与配置和电压形式无关，但它们的比例和比例不同，这反过来又定义了击穿电压的值。作为一个统一的扩展，将根据大气条件对整个分解过程进行分过程区分的、基于测量的评估。根据这项参数研究的电学和光学测量结果，将确定大气对不同击穿子过程物理特性的影响。根据调查结果，将建立关于其子过程拖缆和引导器的击穿过程的物理模型，并依赖于大气条件。对于所检查的任何大气参数，该模型应为任何击穿和耐压提供可靠和一致的大气校正方法。对于绝缘配合下的耐压大气修正，应利用该模型推导出与海拔高度相关的修正方法。

In power supply systems, the insulation of the equipment is stressed by impacts of lightning and switching. An adequate insulation co-ordination and dimensioning requires the knowledge of the correct breakdown voltage in order to avoid damage as a result of dielectric breakdown.Especially for air-gap insulated equipment, the dielectric strength depends heavily on the atmospheric ambient conditions. In turn, the main ambient parameters temperature, air humidity, air pressure and air conductivity – and thereby the breakdown voltage – are dependent on the geographical location of the installation.Current atmospheric correction methods for breakdown and withstand voltages in long air-gap configurations show deviations in comparison to measurement data when applied to correct for unusual or atypical atmospheric conditions (i.e. altitudes above 2000 m a.s.l.). The corresponding standards IEC 60060 and IEC 60071 show inconsistencies, although both are being based upon the same measurements and empirical models. A world-wide discussion of this inadequacy caused the establishment of several working groups, yet so far, a solution could not have been found (IEC JWG 42/22; CIGRE WG D1.50).Therefore, and with the support of the working groups mentioned above, the purpose of this research project is to lay the necessary groundwork for a profound solution. The main goal is to develop a generally valid, physical model of the breakdown process in dependence of the atmospheric parameters and in relation to distinct configurations and voltage forms.The proposed research is based upon the recent knowledge, that any breakdown process in air-gap insulation consists of the sub-processes streamer and leader. While their physical characteristics seem to be independent of configuration and voltage form, their ratio and proportion varies, which in turn defines the value of breakdown voltage. As a unified extension, a sub-process-differentiated, measurement-based evaluation of the entire breakdown process in dependence of the atmospheric conditions will be conducted. Based on the electrical and optical measurement results of this parameter study, the atmospheric influences on the physical characteristics of the different breakdown sub-processes will be determined.Upon the findings of the investigation, a physical model of the breakdown process with respect to its sub-processes streamer and leader and in dependence of the atmospheric conditions will be developed. In relation to any of the examined atmospheric parameters, the model shall provide a reliable and consistent atmospheric correction method for any breakdown and withstand voltage. Regarding the atmospheric correction of withstand voltages in accordance with insulation co-ordination, the model shall be used to derive a correction method in dependence of altitude.