Impact of signal delay attack on voltage control for electrified railways

Cybernated traction power system can be an attractive leverage for attackers who aim to cause catastrophic safety incidents in electrified railways. This paper studies the cybersecurity risks of the traction power voltage control system that regulates the voltages of railway feeder substations. We derive the stability condition of the control system when it is under a signal delay attack, i.e., the timing information of voltage measurements is maliciously corrupted so that the system wrongly uses old measurements to make control decisions. Our analysis and simulations show a fundamental trade-off between the voltage convergence speed when trains´ reactive power draw varies and the tolerable malicious time delay in terms of system stability.