基于垢层动态沉积模型的阀冷系统电极均压能力评估方法

Evaluation method of voltage-equalizing ability of electrodes in valve cooling system based on sediment dynamic deposition model

针对缺少对阀冷系统电极结垢后电极均压能力的评判方法,提出用电压纹波因子α和泄漏电流波纹因子β表征电极均压能力的评估方法。研究了阀冷系统腐蚀与结垢机理,基于腐蚀与电沉积反应建立了电-流-传质场耦合作用下阀段均压电极动态结垢模型,并采用拉格朗日-欧拉方法计算垢层动态沉积过程引起的几何边界变化;基于电路模型和实验结果验证了所提模型的准确性,结果表明垢层动态沉积模型下的结果与测量结果一致,能够有效表征垢层动态沉积特性;最后,提出利用综合考虑各支路电压和泄漏电流波动情况的纹波因子α和β评估阀冷系统电极均压能力,获得了不同结垢程度下的电极均压能力变化规律,确定了以αNM>1、βNM>0.7为阈值的均压电极定期更换/清洗策略。

To address the lack of evaluation methods for the electrode voltage-equalizing ability with sedi⁃ments on grading electrode of valve cooling system,an evaluation method using voltage ripple factorαand leakage current ripple factorβis proposed to analyze the voltage-equalizing ability of electrodes.The corro⁃sion and deposition mechanism of valve cooling system is studied.Then,based on corrosion and electrode⁃position reaction,the dynamic deposition model of valve section grading electrodes that considers the coupling action of electrical field,turbulence field and mass transfer field is established.In addition,the Arbi⁃trary Lagrangian-Eulerian approach is employed to calculate the geometric changes caused by sediment deposition.Based on the circuit model and experimental results,the accuracy of the proposed model is veri⁃fied.Test results show that the results under the dynamic deposition model of sediment are consistent with the measurement results,and can effectively characterize the dynamic deposition characteristics of sedi⁃ments.Finally,the ripple factorsαandβare employed to evaluate the voltage-equalizing ability of elec⁃trodes,which considers the voltage and leakage current fluctuation of each tributary waterway.The variation regularity of voltage-equalizing ability under different scaling degrees is investigated.The strategy of periodic replacement/cleaning of grading electrodes with the thresholds ofαNM>1 andβNM>0.7 is determined.