Beijing, China, October 20th, 2016 – A group of 20 leading HVDC experts gathered in GEIRI’s Power System Power Electronics Laboratory on August 20^th to witness the type test of the 200kV DC circuit breaker designed for Zhoushan multi-terminal system. With a boom from the heavy current interruption test, the DC breaker successfully interrupted a short circuit current up to 15.6KA, which has set a new world record in terms of the breaking capability. 

The fact that VSC-HVDC systems cannot realise rapid clearance of the DC faults has hampered the development of VSC-based overhead line transmission system, multi-terminal HVDC system and DC grid. That’s why GEIRI has devoted itself to the development of DC breaker over the past 4 years. 

With years of intensive research on both topology and equipment, a 200kV prototype came out in early 2015. An advanced concept was adopted by combining mechanical switching based on ultrahigh-speed disconnect switch and power electronics switching based on high-power IGBT full-bridge cascade assembly, which not only avoids the high losses associated with a solid-sate breaker, but also overcomes the limit of switching speed of a mechanical breaker. As the first of its kind in the world, this 200kV DC circuit breaker can interrupt 15kA fault current within 3 milliseconds, 100 times faster than the blink of a human eye.  

In terms of testing methodology, GEIRI has deeply studied the equivalent test mechanism and proposed detailed methods for heavy-current operation test, high-voltage withstand test, short-circuit interruption test and closing test. In terms of testing capacity, a set of full working condition testing facilities was built, which allows assessment of the overall performance of dc breaker in real operation.