Considerations for life extension of HVDC transmission systems

A number of HVDC transmission systems have been in commercial service since the 1960s. As these HVDC systems approach the design end-of-life, owners are reviewing factors that govern end of life and the steps that can be taken to extend operating life. The owner may also be looking for increased HVDC system performance or rating that exceeds original equipment capabilities. This paper looks at considerations that can affect the decision to replace or upgrade key HVDC equipment such as dc controls and valves. The work also examines possible roles of the owner and supplier in the replacement of equipment.