21 kA Solid State DC Breaker for Supergrid Institute’s High Power Test Facility

Abstract:
SuperGrid Institute commissionned its High Power Source (HPS) test platform on June 2022. This plat-form is a new tool for the industry to develop future high-voltage direct and alternating current equipment for the massive integration of renewable energy. The HPS can produce the real high voltage direct current that devices will encounter in the field. This capacity is made possible by the platform’s current rectifier, which converts the current generated by an alternator into a high-voltage direct current. With this platform, SuperGrid Institute can perform both DC (200 kV DC 40kA) and AC short circuit tests at various frequencies from 10 Hz to 60 Hz, and up to 80 kA, on circuit breakers, fault current limiters, etc. The short-circuit generator (SC Gen) is rated 3.45 GVA and is equipped with two different excitation systems: a “conventional excitation” system connected to the distribution grid, that supplies the SC Gen rotor through a 24-pulse controlled rectifier, and a so-called “super-excitation” system, that excites the SC Gen rotor with a current pulse generated from a supercapacitor bank and controlled by a solid-state DC breaker. For this specific switching function, a medium voltage 21 kA static DC current breaker has been developed. Based on sub-assemblies using press-pack IGBT and press-pack diodes that are connected in parallel and in series, this solid-state breaker has been manufactured, tested, installed, and commissioned for a nominal direct current of 21 kA and a nom. voltage of 2.85 kV DC. After a description of the SC Gen test facility with super excitation system, the technical requirements for solid-state breaker and the developed solutions are presented, including measurement results that were taken during breaker qualification testing and commissioning of the new HPS test platform.