A supervisory approach towards cyber-secure generator protection

Abstract

Modern microprocessor-based relays can be vulnerable to attacks from sophisticated cyber-adversaries. In the case of synchronous generators, specifically, out of step (OOS) protection, we show that a “hacked” relay can be made to respond exactly contrary to design, which can be disastrous to system operation. We propose a computational alternative - using the concept of Dynamic State Estimation (DSE) and inputs from Phasor Measurement Units to address this problem. Since DSE does not rely on the “settings” used in traditional relays, it can be used to independently supervise the operation of the traditional relay. The generator's dynamic states are continuously tracked and monitored using the DSE module during steady state conditions and the dynamics following a fault. We show that this approach can detect OOS conditions consistent with traditional schemes, thus supervising conventional protection and help detection of anomalous behavior from a compromised relay. Dynamic simulation results are presented on the IEEE 10 machine, 39-bus system to illustrate the proposed approach.