Evaluation of the vulnerability of phasor measurement units to GPS spoofing attacks

Results from Global Positioning System (GPS) spoofing tests against Phasor Measurement Units (PMUs) are presented, demonstrating that PMUs are vulnerable to spoofing attacks. A GPS spoofer can manipulate PMU time stamps by injecting a counterfeit ensemble of GPS signals into the antenna of the PMU’s time reference receiver. A spoofer-induced timing error of only a few tens of microseconds causes a PMU to violate the maximum phase error allowed by the applicable standard. These and larger errors can give automated or human power grid controllers a false perception of the state of the grid, leading to unnecessary, and possibly destabilizing, remedial control actions. To emphasize this threat, it is shown that a particular PMU-based automatic control scheme currently implemented in Mexico, and whose control architecture and setpoints have been published in the open literature, could be induced by a GPS spoofing attack to trip a primary generator.