Current Derivative Assisted Protection Coordination System for Faster Fault Isolation in A Radial DC Microgrid

In this work, a current derivative assisted protection coordination system between the fast protection devices in a power electronic converter dominated radial DC microgrid is proposed. A circuit based model of a grid connected radial DC microgrid with energy storage unit is developed in PLECS that includes solid-state circuit breaker model as protection device. Microgrid fault dynamics have been analyzed theoretically to modify the standard time graded breaker coordination curve for faster fault isolation. We demonstrate that faster response is achieved by adding a corrective term for breaker coordination based on the derivative of the sensed current and coordinated operation between upstream and downstream protection devices without any active communication. The performance of the proposed approach is compared in simulation with regular time graded breaker operation for validation. In addition, experimental results are provided to demonstrate the effectiveness of the proposed method for faster fault isolation in a 380V DC system.