Pollution flashover behavior of hydrophobic polymeric insulating interfaces at insulators under DC voltage stress and combined DC and AC voltage stress

由于电能是所有部门的关键资源，因此，为了实现限制全球变暖过程的目标以及由于实际战争而取代天然气和石油，对电能的需求正在增加。为了将电能从发电厂传输到用户，需要增加输电线路的容量。此外，电能需求显著增加的时间段（梯度）较短，另一方面，由于不同的原因，新的输电线路的架设从规划到调试将花费一定（通常较长）的时间段。回到20世纪70年代初，已经讨论了通过使用混合AC和DC电压来传输电能，其动机是增加最大可传输电功率。基于最大可转移负载，可升级约。85%的现有输电线路通过使用交流和直流输电的混合。绝缘子需要为混合交流和直流电压以及受污染的环境提供必要的绝缘。为了立即使用混合的AC和DC电压，不需要在传输线路绝缘子和塔处进行任何改变。陶瓷、玻璃和复合绝缘材料的设计是通过交流和直流的长期实践经验来理解和标准化的。对于交直流混合绝缘子的性能和设计，经验和研究有限。特别是，干带放电的行为以及污闪特性可能与电流的过零点丢失有关（前电弧将无法区分）。这种不同的行为将对具有亲水行为（玻璃和瓷绝缘子）以及疏水行为（复合绝缘子）的污染绝缘子的行为产生影响。本研究的主要目的是研究纯交流、直流和交直流混合应力下的污闪特性和示踪侵蚀行为的差异，提取过程，并根据结果调整现有模型。通过这些研究，为交直流混合电压输电线路的设计和使用提供了基础数据。

The demand of electrical energy is increasing to achieve the goals to limit the global warming process and to replace natural gas and oil due to the actual war, because the electrical energy is a key resource in all sectors. To transfer the electrical energy from the generation plants to the users an increasing capability of transmission lines are necessary. Additionally, the time period (gradient) of the significant increase in the electrical energy demand is short, on the other side the erection of new transmission power lines will take certain (usually a longer) time period from the planning till the commissioning due to different reasons. Back to the early 1970s, the transmission of electrical energy by using a mixed AC and DC voltage with the motivation of increasing the maximum transferable electrical power have been discussed. Based on the maximum transferable load can be upgraded by approx. 85 % at existing transmission lines by using a mixed of AC and DC transfer. The insulators need to provide the necessary insulation for the mixed AC and DC voltage in combination with the polluted surrounding. For the immediate usage of the mixed AC and DC voltage no change at the transmission line insulators and towers needs to be done. The design of porcelain, glass and composite insulates is understood and standardized by long-term practical experience for AC and DC. For the behavior and design of mixed insulators for combined AC and DC limited experience and investigations are available. Especially, the behavior of dry band discharges but also the pollution flashover characteristic may be different related to the missing zero crossing of the current (the pre-arcs will not distinguish). This different behavior will have effects to the behavior of polluted insulators with hydrophilic behavior (glass and porcelain insulators) as well also the hydrophobic behavior (composite insulators). The main goal of this research project is to investigate the differences between pure AC, DC and mixed AC and DC stress in the pollution flash over characteristic and the tracking erosion behavior, extract the processes and based on the result to adapt the available models. With these investigations, the fundamental data for the design and usage of transmission lines with a mixed AC and DC voltage are provided.