A New Fast-Acting Backup Protection Strategy for Embedded MVDC Links in Future Distribution Networks

This paper presents a new fast-acting backup protection strategy for future hybrid ac-dc distribution networks. By examining the impedance measured by distance relay measuring from “ac-side” of network, unique characteristic is established faults occurring on “dc-side” an embedded medium-voltage dc (MVDC) link, interconnecting two 33 kV network sections. Based identified characteristic, appropriate settings are developed and deployed verified software model commercially available relay. To remain stable ac-side faults, it found that tripping logic device must be altered to provide correct time grading between standard, ac, zones region, which can identify system within 40 ms. An additional confirmatory check also employed reduce likelihood mal-operation. Trials test derived actual employs protection, shown operation both dc-side pole-pole pole-pole-ground faults.