Study on Corrosion Characteristics of the Contact Strips of the Valve-side Bushing of the UHV Converter Transformer

The valve-side bushing of the UHV converter transformer is one of the key pieces of equipment in the DC transmission projects, which has been bearing the high voltage and large current of the system during long-term operation. As the most commonly used electrical contact element in the valve-side bushing of the UHV converter, the contact strips are prone to deterioration and failure in the harsh operating environment. In this paper, taking the actual fault of the contact strips at the valve-side bushing of a transformer in a UHV converter station in 2021 as an example, the corrosion characteristics of the contact strips in the valve-side bushings were investigated by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), and the microscopic changes of corrosion products during the corrosion deterioration of the contact strips were observed, and the element distribution and main components of the corrosion layer were determined. Through the contact resistance comparison experiment of the contact strips with and without the corrosion layer, the influence of corrosion on the contact performance of the contact strip was studied.