Bidirectional Series-Type DC Hybrid Circuit Breaker With Self-Restart Capability and Energy Regeneration

The series hybrid circuit breaker (SHCB) is a promising solution for fault current breaking in medium and low-voltage dc distribution networks, offering fast fault breaking and low conduction losses. However, the additional circuits or devices required for charging the energy storage (ES) capacitors complicate the restart operation of the SHCB, and the dissipation of large amounts of residual magnetizing current in the transformer results in energy wastage. To address these issues, this article proposes a bidirectional energy-regeneration SHCB (ER-SHCB), which recycles the transformer's residual magnetizing current to charge the ES capacitor, enabling self-restart. This approach simplifies and accelerates the restart operation while achieving ER. In addition, the voltage injection unit can generate a controllable-polarity counter voltage, allowing for bidirectional fault current breaking. To validate the effectiveness of the ER-SHCB, 10 kV/100 A simulations and scale-down experiments were conducted. Results show that the proposed ER-SHCB, featuring self-restart capability and ER, can quickly break the operating and fault currents.