Hardware in the loop verification of a fast backup protection scheme for embedded MVDC links within distribution networks

With increasing interest in the deployment of dc technologies in ac distribution networks, there is a need to ensure compatibility with existing protection systems. This paper presents findings from hardware in the loop investigations which verify a novel approach to providing backup protection to an embedded dc link. This approach reconfigures existing digital distance protection devices to provide fast acting backup protection to embedded dc links whilst still being sensitive to conventional ac side zone faults. A brief overview of medium voltage dc trial projects in Great Britain is also provided.