换流阀内冷却系统均压电极结垢分布规律

Distributing Characteristics of Deposition on Grading Electrodes in Inner Cooling System of Converter Valve

高压直流输电换流阀内冷却系统的冷却结构具有多种类型,但均不能规避针形均压电极的表面结垢问题。现场测量和统计了四重阀塔螺旋型主水路、二重阀塔S型主水路、并联型阀组件内水路等典型结构阀内冷水路中的均压电极结垢厚度分布,统计分析了电场和流体场等环境因素对电极结垢分布情况的影响,计算了内冷水路不同位置均压电极的电流大小及其表面电场分布情况,仿真分析验证了电极电压极性和电流对结垢分布情况的影响。结果表明,均压电极的相对电压极性是影响其结垢程度的主要因素,阀塔和阀组件中高电位处正极电极表面更易形成结垢,结垢厚度与电极表面阳极方向电流直流分量的大小呈正相关,电极表面结垢形态与电极电流的分布情况具有明显的一致性。

A variety of structures are used in the design of the inner cooling systems for HV converter valves,while the problem of deposition on the pin-type grading electrodes is still frequently observed.In this paper,the deposition status in the cooling water ways of the quadruple valve towers,the double valve towers and water ways inside the valve modules are measured and counted on site.The effects of environmental factors including electric field parameters and fluid field parameters are analyzed.The distribution of electric field and electric current on the pin-type grading electrodes is numerically calculated.By means of simulating calculation,the effects of electric polarity and electric current on the deposition distribution are verified.The results show that the relative electric polarity of the grading electrodes is the dominant factor affecting the deposition degree.The deposition tends to occur on the grading electrodes located at the high electric potentials.A positive correlation between the electric current and the deposition thickness on the grading electrode is obtained.The morphology of the deposition is in significant consistence with the distribution of electric current on the pin-type grading electrode.