Reliability and Availability of HVDC Systems

Abstract

Operational performance characteristics including frequency and duration of forced and scheduled outages of the main components within HVDC power transmission systems are of significant interest to the electric utility industry CIGRE Advisory Group B4.04, of CIGRE Study Committee B4 (HVDC and Power Electronics Equipment), has collected data annually on the reliability performance of HVDC systems in operation throughout the world since 1968. The reliability survey began with mercury-arc Line Commutated Converter (LCC) systems and progressed to thyristor valve LCC systems and now includes transistor valve Voltage Source Converter (VSC) systems. The reliability data are voluntarily prepared by utilities that operate the HVDC systems and are submitted to Advisory Group B4.04. In 2018, 66 utilities provided reliability data. This reliability information is analyzed and published biennially at the CIGRE International Conference held in Paris. The data represent performance of systems with varying age, which means that technology evolutions are likely to affect the performance data. Furthermore, the data also represent systems made by several suppliers, which also makes it impossible to obtain statistically valid inferences from the data. Furthermore, very long duration outages contained in the data base caused by some equipment failures for which no spares were available and some large fires will skew the system availability data downwards. This Chapter summarizes the basis for the survey and provides a summary of data from 412 performance reports received from 66 HVDC systems over the 10 year period from 2009 through to 2018. The forced outage statistics by component types (AC and Auxiliary Equipment, Valves, Control and Protection, Primary DC Equipment and Other) are also presented. The reliability of DC transmission lines and converter transformers are also addressed.