Research On Electrochemical Corrosion And Deposition Analysis Model And Influencing Factors Of Converter Valve Cooling Systems

DC transmission system requires cooling water to cool its converter valve system. The corrosion and deposition in cooling water system bring about great risks. DC transmission projects, which has been running for many years, malfunction many times due to the corrosion and deposition, even it may lead to system outages. Few domestic research involve converter valve corrosion and deposition analysis model and influencing factors, which this article undertaking an analysis of corrosion and deposition valve cooling system problems from. Because this study belong to multidisciplinary fields, and related research literature is relatively scarce, so this brings to great difficulties.This paper summarizes the mechanism leading to the cooling system converter valve electrochemical corrosion and deposition based on existing maintenance test results and related research literatures. The study on converter valve corrosion and deposition in cooling water by experimental means of conventional electrochemical measurements is time-consuming and inefficient. Therefore, this article uses a combination method of finite element physical simulation and equivalent circuit modeling.The electrode reaction mainly is deposition reaction. Considering finite element method and electrode kinetics boundary conditions, the current distribution of actual physical model is analyzed. Without considering the electric double layer capacitor, it analyzes the various influencing factors, i.e. applied voltage, temperature, electrolyte conductivity impact on the electrode reaction.Equivalent parameters are extracted from the actual physical model and the equivalent circuit analysis model is established. Comparisons between the physical simulation model of linear electrode-electrolyte boundary conditions and the circuit simulation of linear resistors and capacitors are made in this paper. We analysis the effects of different types of additional excitations for electrode reaction based on the nonlinear equivalent circuit, which considers the nonlinear capacitors and resistors. The proportional relationship between the reaction current and leakage current is obtained under different conditions. The half-wave rectified waveform is selected as excitor, which is similar to the actual project waveform for the study, and the relation ratio of reaction current to leakage current of about 63.75% is obtained, regardless of the magnitude of excitation amplitude. Considered amplitude-frequency analysis of the half-wave rectified voltage excitation waveform, it shows that the main factor affecting the electrode reaction current is the DC component of applied voltage excitation. It has beneficial to further study on the deposition and corrosion of converter valve system.