均压电极垢层电沉积模型分析与应用

Analysis and Application of Grading Electrodes Deposition Model

换流阀是高压直流输电系统中的核心设备,阀冷系统用于阀体组件的散热,而阀冷系统散热器腐蚀和均压电极结垢将导致换流阀运行故障,因此研究阀冷系统的腐蚀和结垢特性,对保障换流站安全可靠运行尤其重要。基于散热器腐蚀和垢层的沉积机理,应用有限元方法,建立了考虑电极表面沉积反应、物质传递过程的均压电极垢层沉积模型,所建模型能够模拟垢层生长过程、分析电极表面附近电场以及腐蚀离子浓度分布。基于该模型分析了电极表面垢层的沉积行为特性、电极表面的垢层分布,讨论了不同电压等级对垢层厚度的影响,得到垢层主要分布在高电位电极、电极尖端垢层量远大于电极平行位置以及电压等级升高,垢层厚度明显增大的仿真结果。结合实际换流站阀冷系统的运行数据和电极结垢形貌,验证了垢层沉积模型的有效性。

The converter valve is one of the core equipment in high voltage direct current(HVDC)system,and the water cooling system is often used for heat dissipation.However,the corrosion of radiator in the cooling system and the sediment on the grading electrode will lead to fault of converter valve.It's therefore essential to study the characteristics of corrosion and deposition in the water cooling system.Based on the mechanism of radiator corrosion and sediment deposition,this paper uses the finite element method to establish a grading electrodes deposition model considering the electrode surface deposition reaction and material transfer process.The built model can investigate the growth process of the sediment,and analyze the electric field near the surface of electrodes and the distribution of the corrosion ion concentration.The deposition behavior of sediment and the distribution of sediment on grading electrodes is studied based on the proposed model,and the effect of voltage level on the thickness of sediment is discussed.The results indicated that the thickness of sediments is proportional to the voltage level,the sediment is mainly concentrated on the high-potential electrode,and the amount of sediment on the electrode tip is much larger than that on the parallel position of the electrode.In addition,the proposed model is verified by the measurement results of actual converter valve's cooling system and the sediment on the electrode.