Implementing a Terrestrial Timing Solution: Best Practices

Abstract

This document is an overview and guide on the concept of precision time and how an alternative terrestrial timing solution to the Global Positioning System (GPS) can be implemented. What follows is a set of recommendations and best practices, derived from research at Oak Ridge National Laboratory (ORNL), across industry, and within the U.S. government, to implement a system of precision timing synchronization to support resilient operations for the U.S. grid. Precision time is a fundamental necessity for operating the grid today, and it becomes even more important as the grid modernizes with clean energy sources, microgrids, and precision sensors placed throughout the grid system to ensure failureresistant operations. The Global Navigation Satellite System (GNSS), which includes (GPS), is currently the primary provider of precision timing today. A terrestrial-based system for time delivery and synchronization to augment GPS is outlined below and it would provide secure time, synchronized with Coordinated Universal Time (UTC), in the event of outages or other interruptions associated with time delivery.

Cyber Resilience in the Cast Timing System

“…Despite the importance of precise timing in the power grid and industrial control system (ICS) architecture, GPS/GNSS continues to be the sole source of timing which has been proven to be susceptible to spoofing and jamming attacks as well as some natural disasters such as solar flares. DarkNet/CAST is the DOE's approach to implementing an alternate source of timing for the electric grid and ICS applications [1]. This approach helps protect critical infrastructure from being completely reliant on GPS timing and leaves room for timing failover, in the event that GPS/GNSS timing is unavailable.…”

“…According to the CAST's Best Practices document, "The explicit purpose of this alternative terrestrial timing solution is to deliver a wide-area synchronization (WAS) capability with precise traceability to Coordinated Universal Time (UTC) to U.S. Power Marketing Administrations (PMAs), Defense Critical Electrical Infrastructure (DCEI), and industry for the support of critical infrastructure and grid reliability, resilience, and security" [1].…”

“…Figure 2: ORNL Timing and Synchronization Lab to Research Sites Map [1] Today, the mission of CAST is to provide the necessary mentoring and technical assistance to build these competencies in a local timing solution and assist federal partners with the evaluation, installation, and operational expertise to implement timing solutions. As a part of that mission, the CAST team established and documented a best practices report for terrestrial timing solutions for research sites and supporting utilities.…”