# GNSS timing for power grids Power grids depend on GNSS timing because phasor measurement units across the network must synchronise their measurements of voltage, current and frequency, with accuracy measured in microseconds. GNSS receivers are comparatively low-cost, reliable and precise sources of that time. Because the power system is so important, the timing signal must also be resilient against interference. ## Why grids need a common clock Phasor measurement units (PMUs) measure the electrical conditions in a power system in real time: voltage, current, power and frequency. Grid operators use them to monitor and control the stability and reliability of the grid [1]. PMUs are deployed at nodes across the network, including remote locations, and they rely on accurate time synchronisation of their measurements [1]. - **PMU shipments in 2025:** just over 8,000 - **PMU shipments forecast for 2034:** around 11,500 - **Measurements per second:** up to dozens - **Time source of many PMUs:** GPS These figures come from the EU Space Market Report 2026, which expects annual PMU shipments to keep growing as utilities expand wide-area monitoring, protection and control schemes [1]. ## How GNSS timing works in the grid Besides position, satellite navigation delivers precise time. GNSS receivers are comparatively low-cost, reliable and high-precision timing sources that can be installed in large numbers across an intelligent grid [3]. Our page on [what GNSS is](https://leto.space/knowledge/gnss/) explains the technology. PMUs typically rely on GPS or another GNSS to synchronise their measurements [1]. The accuracy required is measured in microseconds, because protection and control applications need accurate timestamps and timely delivery of the data. State-of-the-art GNSS receivers meet these requirements [2]. **Figure:** Phasor measurement units (PMUs) typically take their time from GNSS, in many installations from GPS; Galileo could serve as an alternative or backup. The common time lets operators compare data from hundreds of PMUs in real time. Schematic drawing. ## What it enables The digitisation of substations, which supports the spread of PMUs, has improved protection and control applications such as the following, and the quality of data synchronisation is key to them [2]: - real-time modelling of the grid - fault analysis and fault localisation - wide-area monitoring across the network Looking ahead, EUSPA expects GNSS timing receivers to enable real-time automatic control of intelligent grids, in which all energy market participants communicate with each other [3]. ## Resilience Because the power system is important to our lives and economies, GNSS timing in the grid must be resilient against interference [3]. For PMUs, EUSPA names two options: **A second constellation.** Galileo could provide an alternative or backup to GPS in PMUs [1]. **A backup time source.** Precision Time Protocol (PTP) concepts are being explored as a backup, although some of them also rely on GNSS receivers [2]. Detecting jamming and spoofing, including with authenticated Galileo signals, applies to every GNSS-dependent operation and is covered under [protecting GNSS-dependent operations](https://leto.space/use-cases/gnss-resilience/). ## Limits **Limits** - **One system dominates:** Many PMUs are legacy installations or receive GPS only, and Galileo adoption in existing PMU infrastructure is still emerging rather than widespread \[1]. - **Signals can be disrupted:** GNSS signals can suffer interference \[3]. A timing design needs a plan for what the devices do when the signal is lost or manipulated. - **Backups are not always independent:** Some backup concepts based on the Precision Time Protocol also rely on GNSS receivers \[2]. A backup only helps if it does not share the weakness of the primary source. ## How we help We help you find out where your grid depends on satellite time, specify accuracy, resilience and backup in [requirements and procurement](https://leto.space/consulting/procurement/), and introduce the new set-up step by step. [More on implementation](https://leto.space/consulting/implementation/) To see who offers space-enabled solutions, use [Spacegraph](https://leto.space/spacegraph/), our discovery platform. ## Related use cases - [Protecting against jamming and spoofing](https://leto.space/use-cases/gnss-resilience/): How to protect operations that depend on GNSS. - [Forecasting renewable power generation](https://leto.space/use-cases/renewable-forecasting/): How satellite data improve solar forecasts and support wind power. - [Machine guidance and surveying with GNSS](https://leto.space/use-cases/gnss-machine-guidance/): Satellite positioning on construction sites. - [Energy and utilities](https://leto.space/industries/energy-and-utilities/): All use cases for energy companies and utilities. ## Frequently asked questions ### Can Galileo replace GPS for grid timing? Many PMUs still rely on GPS, and Galileo adoption in existing PMU infrastructure is still emerging. Galileo has, however, moved from a supplementary system towards a stronger alternative, and grid operators are beginning to invest in redundant timing such as multi-GNSS receivers [1]. ### What happens if the GNSS signal is jammed or spoofed? GNSS signals can suffer interference, which is why timing for the power system must be resilient against it [3]. For PMUs, Galileo as a second constellation is gaining ground, and grid operators are beginning to invest in redundant timing solutions such as multi-GNSS receivers, terrestrial backup systems and network-based time distribution [1]. Detection, authenticated signals and backups for all GNSS-dependent operations are covered in our use case on [jamming and spoofing](https://leto.space/use-cases/gnss-resilience/). ### How do we start? Start with an inventory: which devices in your substations and control systems take their time from GNSS, which receivers they use, and what happens when the signal is lost. From there we define requirements for accuracy, resilience and backup. Our [consulting overview](https://leto.space/consulting/) shows the path from the problem to operation. ## Sources 1. [EU Space Market Report 2026, Issue 1, EU Agency for the Space Programme (EUSPA), 2026-05-26](https://www.euspa.europa.eu/sites/default/files/documents/EU_Space_Market_Report_2026.pdf) 2. [EUSPA EO and GNSS Market Report, Issue 2, 2024, EU Agency for the Space Programme (EUSPA), 2024](https://www.euspa.europa.eu/sites/default/files/external/publications/euspa_market_report_2024.pdf) 3. [Timing is everything: GNSS and the energy grids of the future, EU Agency for the Space Programme (EUSPA), 2020-12-15](https://www.euspa.europa.eu/newsroom-events/news-archive/timing-everything-gnss-and-energy-grids-future) Page: