GPS protects power networks against failure

Our pioneering global positioning system (GPS) based method for preventing electricity blackouts has been included in international grid management standards and also features in technical guidelines on best practice. National Grid expects to save £0.5 million each year as it implements the system across the UK.

GPS protects power networks against failure, School of Electrical and Electronic Engineering

For an individual, a power cut probably means no hot drinks, perhaps no heating and an excuse to light candles, stop work or go to bed early. However, the costs of power failures are immense. In 2003, a blackout in the USA caused 11 deaths and cost the country’s economy $6 billion. A recent blackout in India affected 700 million people.

As demand for electricity continues to rise in the UK, the national power transmission and distribution networks are under increasing stress. Our researchers have helped to address the problem by developing new ways of controlling and protecting the power network from potential failure.

Value

The value of the global market for GPS synchronised differential protection.

Savings

The annual saving from GPS synchronisation in the UK.

The cost of a single large HV transformer

Cost

The cost of the 2003 blackout to the US economy.

Our pioneering method makes use of the time signals from global positioning system (GPS) satellites. GPS allows the power grid to synchronise its entire infrastructure – a critical step when it comes to controlling equipment switching or programming generation to go on or offline.

Grid protection is set to change in many countries as a result of our work. The International Council on Large Electrical Systems (CIGRE) has published a technical brochure that includes some of our methodologies and findings; this will influence network protection strategies around the globe.

The international standard for digital electrical substations (IEC61850) has also been updated recently to include time synchronisation across power networks. For the first time, the standard now covers methods for protection and control of substations.

Grid management and protection is set to change in many countries as a result of our work.

In the UK, on the basis of our work, National Grid has changed its national strategy on the integration of control and protection functions within a substation. Our work has also informed National Grid’s policy “Architecture for Substation Secondary Systems” which defines the functional architecture for all new protection and control systems in the UK’s power transmission network.

Six researchers joined Alstom and National Grid to turn our research and prototypes into commercial products. Alstom Grid now offers a commercial differential protection device using centralised GPS-synchronised time servers.

National Grid is implementing GPS synchronisation as part of its low carbon network; it expects to save £0.5 million per year once the technology is rolled out to all refurbished and new-build substations. Globally, the potential savings from using GPS-synchronised differential protection could be worth around £10 million.

Research background

Researchers, led by Professor Peter Crossley, have developed algorithms, prototype devices, concepts and operating strategies to enhance the reliability of protection systems used in electrical transmission networks. Their work focused on network synchronisation using time signals from global positioning system (GPS) satellites.

Key research outputs:

  • Use of GPS time signals to synchronise feeder differential protection.
  • Quantitative methodology for calculating the reliability of integrated control and protection.
  • Strategy for wide area synchronised differential protection to avoid the poor reliability and selectivity of conventional ‘back up’ protection.
  • Quantifiable method to assess system integrity protection schemes (SiPS).
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