A Hierarchical Microgrid Protection Scheme using Hybrid Breakers

Compared with the traditional power grid, the Microgrid with high penetration of converter-based renewable energy faces different protection challenges, e.g., different short-circuit levels in different operating modes, bidirectional fault coordination, ride-through capability, etc. Thus, the traditional mechanical circuit breaker with a relatively slow response time, requirements to operate at high fault currents and the single directional characteristic based protection system cannot satisfy the modern Microgrid demand. Accordingly, a new protection system to solve the new problems in Microgrid is essential. Fortunately, with the development of power electronics, circuit breakers (solid-state circuit breaker, hybrid circuit breaker) with fast response time and bidirectional characteristics gradually emerge. With these new breaker options, this paper proposes a novel hierarchical protection scheme based on the different response times among the solid-state circuit breaker, the hybrid circuit breaker, and the traditional mechanical breaker to better protect a campus Microgrid. The campus Microgrid is studied to verify the effectiveness of the proposed hierarchical Microgrid protection scheme.