A Passive-Active Intrusion Detection Scheme for Multiterminal HVdc Grid Line Protection Attacks

Emerging multiterminal dc (MTdc) grids are envisioned to be highly reliant on information communication technology, making them vulnerable to cyber-security threats. In particular, digital substations that house dc-side line fault protection schemes can be compromised by manipulated measurement signals that resemble actual faults, resulting in outages of dc transmission lines. Therefore, it is imperative to defend against such cyber-attacks. To this end, this article proposes an intrusion detection scheme (IDS) for dc line protection schemes. The IDS comprises two stages, passive and active, that operate sequentially. In the first passive stage, the IDS analyzes voltage and current measurements to detect potential cyber-attacks. In the second active stage, the hybrid solid-state dc circuit breaker is actively controlled to identify attacks that evade the passive stage and achieve a moving target defense. The IDS i) conforms with the MTdc grid protection requirements, ii) only utilizes local measurements, and iii) is universal as different algorithms can be incorporated in this scheme while its hybrid passive and active structure stays intact. Off-line simulation and experimental performance evaluation results demonstrate that the IDS is able to detect a variety of cyber-attacks, including the fully-synchronized replay attack (one of the most sophisticated and stealthiest attacks).