Resonant Network-Based MVDC Circuit Breaker Topologies With Fast Current Breaking Capability

Abstract

This paper presents two improved circuit breaker (CB) topologies based on resonant networks for medium voltage DC (MVDC) applications, such as shipboard power distribution and subsea oil and gas production. The topologies feature simple LC resonant networks that efficiently suppress fault current in just a few tens of microseconds, making them suitable for integration with existing solid-state or hybrid DC CB. Moreover, they also help to minimize the CB energy and reduce (if not eliminate) the requirement for protection devices like surge arresters during fault events. The proposed topologies are first tested using Typhoon Hardware-in-the-Loop (HiL) simulations at 1.2 MW (6 kV, 200 A) power levels and thyristor-based solid-state circuit breakers (SSCB). Then, scaled-down laboratory prototypes, also based on thyristor-based SSCB, are experimentally validated. The results show that both topologies quickly bring the current of the CB's main switch to 0 A. The main circuit pathway requires only a small inductor and switch, resulting in a steady-state efficiency of >99.9%. The resonant network-based design allows for a fast response time of less than 50 µs using a simple and low-cost auxiliary circuit, eliminating the need for complex charging circuitry and protection devices typically used to suppress voltage surges during faults.

An Overview and Minimum Fault Ramp Rate Analysis of Impedance Based Circuit Breaker Topologies

“…Added resistor and diode across the short path capacitor enhances charging the capacitor, and the additional switch S2 acts as a manual switch to turn off the CB. Improved to the previous circuit, in [68], a bidirectional coupled inductor CB is proposed, and it is tested using simulation tools for a Ring DC bus microgrid system. For the designed ring bus microgrid, different control schemes to control multiple CB's is tested and analysed.…”