天广直流工程换流阀冷却系统腐蚀与沉积

为了找到天广直流输电工程运行5年后换流阀冷却系统中存在较严重的腐蚀与沉积,形成的垢质阻塞冷却水路进而使元件散热不畅而烧毁直流输电系统故障的成因和解决方法,检验了阀冷系统相关元件材质与水质,依据沉积物成分分析结果并结合电化学反应理论初步给出了阀内冷水系统腐蚀与沉积现象发生的物质基础与过程机理。试验与分析表明,在为晶闸管散热的铝质冷却座中,金属铝在水中的的电化学反应是导致阀冷系统中腐蚀与沉积的根本原因。

Primary Analysis on Corrosion and Deposit in Valve Cooling System of Tian-Guang HVDC Project

From 2005 to 2006,several system shutdown due to valve cooling faults took place in succession in Tian-Guang HVDC power transmission system.A thorough investigation discovered that there was severe corrosion and scaling problem laying in the thyristor valve cooling system.On the one hand the deposit led to the block of cooling circuit and thus the relevant electrical elements burnt out due to the poor cooling effect,on the other hand,corrosion of O-ring in the tube connector depress the sealing characteristic,which lead leakage of inner water.A detail check and lab analysis to the relevant cooling elements material and water quality was called up for the reason and solution.On the base of lab analysis result and electrochemical theory,a preliminary conclusion of the mass foundation and process theory for valve cooling system corrosion and scaling is given out.The test and its result analysis shows that,main part of the deposit and corrosion material is aluminum compound.Consider that the heat sink is the only aluminum component in the valve cooling system,electrochemical reaction in water environment combining with aluminum,the mail material building up the heat sink of valve,is the fundamental reason led to the corrosion and scaling in the valve cooling system.Moreover,light deposit has also been found during the electrode check at Zhaoqing station-the inverter station of Gui-Guang HVDC system.The reason is considered to be similar with Tian-Guang HVDC system.The further study to this process is under taking.