Robust and Secure GPS-based Timing for Power Systems

Summary Statement

The GPS time-synchronized readings of Phasor Measurement Units (PMUs) provide assistance with real-time operations and off-line analysis to improve the reliability and efficiency of the bulk electric system. Unfortunately, the GPS signal is weak and vulnerable to jamming, meaconing and spoofing. As such, there is a concern that the GPS-based time synchronization of PMUs may be a potential point of entry for attacks on the power system. To address this concern, we propose a multi-layer scheme for the reliable, robust and secure GPS-based time transfer to PMUs. We investigate eight countermeasures in three layers: GPS raw signals layer; semi-processed layer; and fully processed layer. We also develop at GPS simulator/ receiver testbed capable of investigating spoofing attacks and mitigation schemes specific to the use-case of PMUs.

Energy Delivery System (EDS) Gap Analysis

The application of GPS/GNSS in the power sector can potentially have significant impact on the bulk electric system through its integration into synchronization devices, such as Phasor Measurement Units (PMUs). Given that PMU technology is expected to transition to control applications in the future and that the primary wide area time synchronization mechanism used by PMUs (today) is GPS, there is growing concern that a dependency on GPS will introduce a built-in vulnerability into the infrastructure. This activity addresses that vulnerability by investigating spoofing vectors that can adversely affect PMU accuracy, and devising mitigation schemes to counteract these attacks, thereby enabling the adoption of GPS/GNSS synchronized PMUs while advancing EDS resiliency.

Reference the research activity fact sheet (PDF) for an extended gap analysis and bibliography.

How does this research activity address the Roadmap to Achieve Energy Delivery Systems Cybersecurity?
Our research activity addresses the strategy framework representing “Develop and Implement New Protective Measures to Reduce Risk” of the Roadmap. Our work outlines new protective measures that are essential to improve the resilience of phasor measurement units (PMUs) against external GPS timing attacks. Implementation of our multi-layer scheme will provide synchronized phasor measurements up to an accuracy of 100ns, reduce the system risks against external timing attacks and ensure continued robust performance even in degraded scenarios. The results of the activity also enable WAMS to operate through jamming and spoofing attacks.

If successful, we believe that adoption of our results will elevate the maturity of WAMS, along the risk, threat, and dependencies domains as described in the Es-C2m2 [8], to maturity indicator level (MIL) between 2 and 3.

More Information

Research Posters:

• Robust and Secure GPS-based Timing for Power Systems (2020 Industry Workshop)
• GPS Multi-Receiver Joint Direct Time Estimation and Spoofer Localization (2018 Industry Workshop)
• Algorithm and Validation of GPS-based Direct Timing Estimation for PMUs (2017 Industry Workshop)
• GPS-Based Direct Timing Estimation for PMUs (2016 Industry Workshop)