A novel controllable capacitor commutation based superconducting hybrid direct current breaker.

Area of Science:

• Electrical Engineering
• Power Systems

Background:

• Voltage source converter medium voltage direct current (VSC-MVDC) systems are crucial for grid-tied renewable energy.
• High operational safety necessitates circuit breakers that balance response speed and installation cost for fault isolation.

Purpose of the Study:

• To propose a controllable current commutation based superconducting DC circuit breaker (CCCB-SDCCB).
• To enhance DC fault isolation by integrating resistive type superconducting fault current limiters (R-SFCL) with integrated-gate-commutated-thyristor (IGCT) based hybrid DC circuit breakers.

Main Methods:

• Integration of R-SFCL with IGCT-based hybrid DC circuit breakers.
• Implementation of a novel current injection circuit branch using an H-bridge structure for capacitor voltage recycling.
• Utilizing simulation to validate the CCCB-SDCCB's performance.

Main Results:

• The proposed CCCB-SDCCB greatly enlarges current interrupting capacity at low cost and high speed.
• Fault current was successfully suppressed from 24.2 kA to 2.1 kA.
• Complete fault current interruption was achieved within 4.11 ms.

Conclusions:

• The CCCB-SDCCB offers a cost-effective and fast solution for suppressing large fault currents in MVDC systems.
• The novel current injection circuit eliminates the need for capacitor pre-charging, improving operational efficiency.