Current-induced corrosion of aluminium heat sinks in water-cooling systems for high-voltage direct-current converters

ABSTRACT

The effects of leakage electric currents in water on the corrosion of heat sinks in high-voltage (±500 kV) direct-current converter cooling systems are presented. An experimental water-cooling setup was established, and simulated operating experiments were conducted. Electrolytic corrosion experiments with aluminium sheets were carried out. Results of the simulated operating experiments reveal that the micro leakage currents which are mostly distributed within a 4-mm-long region inside the heat sinks result in significant corrosion of aluminium under high-voltage operating conditions. Through quantitative and morphological analysis of the electrolytic corrosion experiments, the anodic or cathodic leakage currents through heat sinks are inferred to induce stray-current corrosion or alkaline corrosion, respectively. Additionally, the effects of leakage currents on increasing the alkaline condition are verified. The obtained results indicate the long-neglected impact of leakage currents in HV converter cooling systems and lay the groundwork for evaluation and prevention of corrosion in metal heat sinks.

KEYWORDS:

• Corrosion
• leakage electric currents
• water-cooling circuit
• aluminium
• HVDC converter valves

Disclosure statement

No potential conflict of interest was reported by the authors.