GPS Spoofer Localization for PMUs using Multi-Receiver Direct Time Estimation

Bhamidipati, S. and Gao, G.

Proceedings of the 30th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2017), Portland, Oregon, September 2017, pp. 2780-2784.

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The modern power grid depends on synchronized phasor values obtained from distributed Phasor Measurement Units (PMUs). When the current power system is transferred to an automated smart grid in the future, these PMU measurements are crucial for high-resolution grid state estimation and early-stage detection of destabilizing conditions. Per the IEEE C37.118 standard PMU specifications, the maximum tolerable clock synchronization error between different PMUs should not exceed 26.5 microseconds (for a 60Hz system). The operation of PMU relies on accurate time keeping sources, such as GPS to obtain precise timestamps.

GPS has advantages of providing beyond microsecond level timing accuracy and is freely available to all users. In addition, the GPS constellation has global coverage, which enables network-wide stability monitoring of power grid. However, given the unencrypted nature and low signal power, GPS signals are vulnerable to external timing attacks. The susceptibility of GPS signals to jamming and spoofing leads to potential threats in the power system. Compared to jamming, spoofing is more sophisticated and can be used to manipulate the PMU with wrong time.

The objective of our research is GPS spoofer detection and localization using Multi-Receiver Direct Time Estimation (MRDTE) for PMUs. In this paper, we propose a multi-receiver architecture that simultaneously estimates the spoofer location (if present) and GPS timing (given as input to the PMUs). The underlying algorithm of our approach is based on a novel signal processing technique known as Direct Time Estimation (DTE) that has been proposed and validated in our earlier work using both single and multiple receivers [1]. DTE performs correlations of the incoming signal with the cumulative satellite signal replica for pre-generated set of clock candidates, and then evaluates the maximum likely clock bias and clock drift for the given instant based on the maximal correlation. It works directly in the navigation solution domain without calculating intermediate pseudorange measurements.

Received Best Presentation of the Session Award. 

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