Robust GPS-Based Timing for PMUs Based on Multi-Receiver Position-Information-Aided Vector Tracking

Reliable and precise electrical wave measurements are essential to the stability and efficiency of a power system. Phasor Measurement Units (PMUs), also known as synchrophasors, are devices that provide precise synchronized voltage magnitude and phase measurements at a high sampling frequency. Widely regarded as one of the most vital devices in monitoring and control for the future of power systems, PMUs rely on the Global Positioning System (GPS) to provide the absolute time reference necessary to synchronize phasor measurements. The dependence of PMUs on GPS introduces new vulnerabilities to a power system utilizing PMUs. The unencrypted nature and low received signal-to-noise ratio (SNR) of civil GPS signals opens risks for malicious parties to broadcast falsified civil GPS signals with the intentions of altering the position or time solutions generated by the GPS receivers [1]. Our goals are to provide robust GPS time transfer for PMUs and to rapidly detect malicious spoofing attacks. Given that the GPS receivers used by PMUs are static, we employ position-information-aided (PIA) vector tracking loops which have been shown to improve the accuracy of the time solutions, robustness against noise and jamming, as well as the ability to detect meaconing attacks [2]. In this paper we extend the single-receiver PIA vector tracking to the multi-receiver case by connecting each of the receivers to the same stable atomic clock and processing the data in a multi-receiver PIA vector tracking loop. Our tests show that this countermeasure can successfully detect meaconing and data-level spoofing. Our approach also significantly improves robustness against jamming and accidental receiver errors.