基于雨水混合物模型的平抗直流套管的雨闪故障分析

Rain Flashover Analysis of HVDC Reactor Bushing Using Rainwater-Air Mixture Model

雨闪故障一直是电力系统外绝缘研究领域的热点。结合有限元方法,进行500 k V直流系统平波电抗器出线套管的雨闪故障分析。通过引入雨水在空气中所占体积比的方法,将水滴和空气等效成单一的混合物介质。通过流体场-电场的耦合分析实现了下雨条件下套管电场的求解。计算表明,下雨时套管上端更易受到雨水的碰撞、集聚,致使局部电场强度增大,此时套管上端表面电场强度相比于干燥环境下更高,更易形成闪络。通过与雨闪故障现场图片对比,仿真结果与实际事故中发生闪络的位置一致,验证了考虑雨水混合物模型在雨闪故障分析中的准确性。

Rain flashover analysis has always been a hotspot in the high voltage insulation research. By using finite-element method,a rain flashover fault in the HVDC bushing of 500 k V reactor has been analyzed. In order to simulate the electric field of the HVDC bushing in the rain,the rainwater and air are assumed as one mixture with equivalent material properties,which are determined by their proportion respectively. Hence,by using the equivalent material properties in the mixture model, the coupling of fluid flow-electric field can be implemented. Simulation results indicate that the rain flashover is more likely to occur on the upper end of the bushing. Owing to the collision and aggregation in the rainwater-air mixture,the electric field intensity in the rain on the upper end of the bushing increases significantly compared to that in the dry environment. Compared with the scene photographs,the actual position where rain flash occurred agrees well with simulations and the veracity is validated.