A cyber-resilient adaptive impedance-based protection scheme for POTT-based distance protection

The growing need for fast and dependable protection has made communication-based protective schemes a key approach for enhancing both the protection and stability of power systems. In recent years, there has been growing use of digital-based communication-assisted distance relays (CADRs) for the protection of transmission lines. Among the most widely adopted approaches within CADRs is the permissive overreaching trip transfer (POTT) scheme, which relies on zone-2 element of the CADR for its operation. However, the dependency of CADRs on digital communication infrastructure introduces significant cyber-security vulnerabilities. This paper presents a detection framework designed to identify both false data injection (FDI) and denial-of-service (DoS) attacks targeting the POTT-based CADRs. In the proposed method, an adaptive multi-cycle supplementary impedance-based element works in parallel with the main POTT scheme. This backup layer becomes operational specifically under cyber-attack conditions that disable the primary protection functions. Since the cyber-attack detection algorithm relies on local measurements, it remains effective during communication channel disruptions. Moreover, as the method is fundamentally impedance-based, it is inherently compatible with the computational logic of CADRs. Simulation studies carried out on the 9-bus test system confirm the effectiveness of the proposed approach.