换流阀内冷却系统均压电极结垢的计算

换流阀内冷却系统中的均压电极结垢现象威胁着直流输电工程的安全可靠运行。建立了单、双和三电极3种典型结构电极系统的计算模型,提出了带电粒子由向电极聚集直至在电极表面沉积的两阶段分析方法,采用有限元法计算了不同流速冷却水及电极电流下均压电极周围带电粒子的分布特性,运用电泳沉积仿真原理计算了带电粒子在各电极体系表面沉积的过程,结果表明循环流动冷却水中电极对带电粒子的捕获存在电流阈值,工程实际条件下单、双和三电极的捕获率分别约为12.6%、33.3%和33.9%,运用电泳沉积仿真原理计算得到的结垢在形态和生长特征上与工程实际具有极高的一致性。

Computation of Deposition on Grading Electrodes in Inner Cooling System of Converter Valves

The safe and reliable operation of high voltage direct current transmission project is threatened by the problem of deposition on grading electrodes in the inner valve cooling water system.In this paper,the calculation models of single,double and triple grading electrode systems are established in order to analyze the aggregation stage and deposition stage of the discharged particles in inner cooling water.By means of finite element method,the distributing characteristics of the charged particles around the grading electrodes are calculated.Furthermore,the deposition process on the surface of grading electrodes is revealed through simulation calculation according to the electrophoretic deposition principle.The results show that a threshold value of electric current exists on the grading electrodes when capturing the charged particles.In the engineering condition,the capturing rate of the charged particles by single,double triple electrode system is 12.6%,33.3%and 33.9%,respectively.The morphology and growth characteristics of the deposition by simulation of electrophoretic deposition are in high consistency with the deposition in the engineering practice.