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Case studies: Energy distribution
To support the Energy Union strategy, the EU has set ambitious targets on the amount of energy to be produced from renewable sources. However, these forms of energy are more decentralised than conventional power plants leading to problems which can destabilise the network.
Using new technology designed to assess power flow, such as phasor measurement units (PMUs) and novel current and voltages sensors, ‘smart’ grids can monitor electricity status in real-time over larger distances, and automatically respond to problems. However, a major challenge is the lack of calibration standards to validate new instrumentation. Furthermore, as these new devices must be able to communicate over the internet, this could leave the system vulnerable to cyber-attacks.
For the foreseeable future nuclear energy generation is likely to continue but next generation plants will be considerably different from those operating today and new measurement methods will be needed for their safe and effective operation.
Protecting the power network from electrical faults
The removal of power loads in electricity grids, such as switching electricity to different routes, can cause electrical surges lasting billionths of a second. However, measurements to protect high voltage substations lacked traceability for over-voltages of this duration. In addition, on-site measurements to assess the insulation condition of high-voltage equipment lacked both traceability and procedures for ‘partial discharge’ events, potentially endangering power supplies.
Metrology to protect the high voltage grid
European electricity networks are upgrading to better integrate renewable energy and increase efficiency. To reduce electrical waste transmission system voltages are changing – but tests designed to protect connected grid instrumentation had not been assessed for these new levels. Without new metrology electrical problems could go undetected, resulting in component failure, compromising power supplies.
Ensuring the applicability of tests for high voltage networks
To reduce power loss during transmission electricity networks are transitioning from high voltage alternating current to more efficient high voltage direct current .However, existing international standards detailing methods to protect connected instrumentation were not intended for high voltage direct current. New methodology to update standards is required to prevent grid component failure, power losses and blackouts endangering future electricity supplies.
Improved nuclear incident data analysis
First responders dealing with radioactive emergencies and National Metrology Institutes (NMIs) investigating radioactivity measurement data experience the same problem: the inability to spot and understand small discrepancies that undermine result accuracy. Digitised radiation detectors enable the recording of raw data,
facilitating subsequent re-analysis utilising different settings or algorithms. However, the lack of data format standardisation hinders interoperability between hardware and software, reducing user uptake of digital technology.
Smart, stable grids for a greener Europe
The EMRP project Metrology for smart electrical grids developed calibration equipment, software and processes that enable phasor measurement units (PMUs) – the ‘life support monitors’ of smart grids – to be validated against traceable measurement standards for the first time in Europe. Tests of PMUs in operational grids in Greece and Sweden resulted in best practice guidelines for PMU use, which have been incorporated into a revision of the relevant IEEE standard used by the industry.
Fluke Corporation, a manufacturer of testing and calibration equipment, has introduced a PMU calibrator based partly on the methods developed in the project. The calibrator enables operators to demonstrate compliance with the revised IEEE standard, and confidently compare PMU measurements across the grid, safe in the knowledge that all devices produce consistent and robust measurements. Arbiter Systems, a manufacturer of precision timing and power measurement devices, is introducing an improved and cheaper combined PMU and power quality measurement instrument for smart grids following involvement in the project. Grid operators will be able to use Arbiter’s new device to demonstrate compliance with the revised IEEE standard, and make reliable grid stability measurements at an affordable price.
Increased access to cost-effective calibration services and devices, such as these, will help operators ensure the stability of smart grids and accelerate their adoption in Europe, supporting widespread renewable energy generation and a more stable, low-carbon energy future for Europe.
Supporting smart renewable energy
With support from South Dublin City Council, the International Energy Research Centre (IERV - National Tyndall Institute), Siemens, Intel and Microsoft, the Micro Electricity Generation Association (MEGA) is piloting a ‘smart energy cluster’ in the outskirts of Dublin, which links small-scale renewable energy generators with local consumers through a smart grid. MEGA’s smart cluster distributes locally-generated wind and biogas power using a power stabiliser incorporating a PMU, which links the cluster to the main grid system and allows inflow of power when renewable generation cannot meet local demand.
Through engagement with the EMRP project Metrology for smart electrical grids, MEGA received help evaluating the smart cluster’s PMU and best practice guidance to enable accurate grid stability monitoring. Support from the project will help to ensure a reliable power supply to users of MEGA’s smart cluster and the success of the pilot project. MEGA hopes to eventually interconnect local small-scale smart grids into a citywide system for Dublin. This will be an important step towards widespread renewable energy generation in Ireland and a more stable, low-carbon energy future for Europe.
New instruments for new power grids
Electricity from renewables is helping reduce the emissions that would otherwise be produced from fossil fuels, but network operators struggle in integrating these more distributed sources of energy. One solution is to use smart grids capable of monitoring and responding to network conditions in realtime, helping to increase stability and optimise efficiency. However, realising these grids requires the development of a new generation of measuring instruments.
A new calibration for current sensors
Lowering carbon dioxide emissions from fossil fuels requires an increased use of renewable sources for electricity generation. Integrating these nonconventional energy sources into the grid can cause problems with supply security and power quality. New current and voltage sensors are needed to monitor network performance, and these will require different calibration methods to ensure their accuracy and traceability to the SI.
New sensors for the high voltage grid
Conventional electricity grids are being replaced by smart grids which can rapidly respond to changes in electricity flow in real-time and better integrate energy from renewable sources. To monitor these grids a new generation of network sensors, termed ‘low-power instrument transformers’ are being introduced which must be compliant to international standards. However, the variety of primary sensors, and secondary converters, brings up new challenges for the calibration of such instruments.
Next-generation nuclear power
The EMRP project Metrology for new generation nuclear power plants developed, tested and patented a new temperature sensor, capable of operating at temperatures up to 1300 °C . Unlike previous instruments, these sensors can be used to ensure the safety and reliability of upcoming Generation IV nuclear reactors, which operate at higher temperatures to offer increased electricity production with reduced waste reprocessing requirements. The Idaho National Laboratory in the US recently held a comparative laboratory test campaign between several conventional thermocouples and a new one developed in the project at the University of Cambridge to select viable temperature sensors for its upcoming Very High Temperature Reactor fuel test validation. Following the lab test campaign Dr Michele Scervini from the University of Cambridge was awarded the opportunity to test the new sensor in Idaho’s prototype reactor, one of only a few facilities of its sort in the world.
Testing will assess the new sensor’s performance in the high radioactivity and temperature environment of Generation IV reactors. This will provide the validation needed to encourage the sensor’s adoption by the conservative nuclear industry, paving the way to next generation nuclear power plants and stable, low carbon energy for Europe.