Improvement of LC resonance characteristics through superconducting elements of DC circuit breaker

To achieve carbon neutrality, the world is researching MMC-based HVDC system. To expand MMC-HVDC, a transient state analysis considering DC characteristics must be established. For this, the implementation of a DC circuit breaker must be preceded. In this paper, LC resonant DC circuit breaker is studied. When the DC circuit breaker is applied to MMC-HVDC, the magnitude of the fault current varies depending on the location. In Zhangbei, where MMC-HVDC is actually built, there is a difference of about 5 kA depending on the location of the DC circuit breaker. A change in the fault current causes a change in the resonant frequency. The values of inductance and capacitance must be changed for LC resonant. To improve this, superconducting fault current limiter modules with different critical currents were connected in parallel. The Zhangbei system was modeled with PSCAD/EMTDC and the superconducting LC resonant DC circuit breaker was applied. As a result, it was confirmed that the interrupting was successful even when the inductance and capacitance were fixed.