Distributed agents structure for current-only adaptive relaying scheme reinforced against failures and cyberattacks

This paper proposes a directional overcurrent protection scheme based on distributed agents. The method does not involve voltage measurement for the current direction function as in conventional relays. Also, the relay exchanges only five binary digit information with a companion agent or a few adjacent agents to check a fault. Hence, the associated communication system is simplified and economical. The current setting of the relay is updated automatically by a fuzzy rule-base mechanism to track the network conditions. The suggested design can promptly isolate the deceitful near-to-end line faults and faults on busbar. It delivers the fault category and works nicely over a wide range of fault impedances from zero to 150 Ω. To block cyberattacks, an agent has a customized unit to firmly discriminate fault from other possible states. Thus, false data injected by hackers are spotted. Furthermore, the scheme can switch to an alternative operation strategy on sensing a communication or hardware failure. The full model of the scheme is dynamically simulated. The scheme is applied to the IEEE 9-bus system and the IEEE 39-bus system. The scheme response to more than 60 test conditions is assessed and results are analyzed. The scheme is found 100 % accurate and can trip the fault within 20 ms.