Review of HVDC Circuit Breakers Topologies

Voltage Source Converter-High Voltage Direct Current (VSC-HVDC) is the most efficient and reliable method for electrical power transmission over long distances. The greatest challenge with VSC-HVDC system is that short-circuit faults damages the converter valves and the transmission network. The fault clearing time for the available DC breakers are not fast enough and reliable to provide adequate protection for DC faults on multi-terminal networks. Hence, the development of fast DC breakers has been ongoing for some time and significant contributions have been made especially on the DC breaker response time and provisions to force artificial current to cross the zero current point. Though with these improvements, the research on fast DC breaker continue to attract a lot of interest. In addition, the integration of large amount of wind power to a conventional power grid demands a fast DC breaker. The need to integrate large amount of wind power has necessitated the development of VSC-HVDC system with multi-terminal systems. This ensures that under the influence of severe short-circuit faults, only the affected converters will be switched off while normal supplies to other converters remain uninterrupted. Currently, there are various types of DC breakers at the market while others are at various stages of development. This paper review and compares the available DC breakers topologies, recent developments made, challenges encountered and recommendations for DC breakers improvement.