World-first fault current technology for London
25 July 2017
ABB is partnering with UK Power Networks (UKPN) in the NIC-funded PowerFul-CB (Power Electronic Fault Limiting Circuit Breaker) project that will alleviate London’s congested electrical distribution networks in readiness for the connection of more distributed generation (DG), including combined heat and power (CHP) schemes.
The PowerFul-CB project, which is funded by the Network Innovation Competition (NIC), administered by UK regulator Ofgem, addresses the growing fault current challenge being faced by London’s power distribution networks as they connect an increasing number of distributed generation (DG) resources.
Currently, most of London’s power is generated outside the city in power stations where large quantities of heat are lost to the atmosphere. One of the aims of the London Plan is for onequarter of London’s heat and power to be generated in the capital by 2025, which could reduce carbon dioxide emissions by more than 2.5 million tonnes annually.
This is likely to lead to significant growth in CHP schemes, which are highly efficient in generating heat and power simultaneously and so consume less energy than conventional energy systems in meeting the same energy demand.
Many large offices and housing developments in London already have their own CHP units, which capture the heat created as a by-product of electricity generation and circulate it around the buildings instead of using separate boilers. CHP units are up to 30 percent more efficient than having separate electricity generators and boilers, potentially leading to significant cost savings for consumers, as well as cutting emissions.
Fault level constraints
Achieving these aims, however, is challenging given the fault level constraints that a rapid introduction of CHP schemes would place on the distribution network without prohibitively expensive infrastructure upgrades, or advances in technology. In London, the already limited headroom in substations would soon be exhausted. In one scenario, with the capital seeing a greater than six-fold increase in connecting CHP by 2031, some 73 percent of substations in the capital would require faultlevel reinforcement.
Fault current occurs when there is a fault on the network (normal current is a steady flow of electricity through the network) and is characterized by an instantaneous surge of electrical energy, which flows towards the point of the fault.
Fault level is the potential maximum amount of fault current that will flow when a fault occurs. Additional demand and generation – including CHP schemes – connecting to the network increase fault level. Fault level fluctuates throughout the day depending on the network configuration and customers’ load or generation. The ability to actively manage and mitigate fault level is a valuable tool for Distribution Network Operators (DNOs).
Fault current technology breakthrough
UK Power Networks established the PowerFul-CB project to evaluate innovative fault current limiting technology on 11 kV distribution networks. The company estimates that by 2050, this new technology could save UK customers around £400 million in reinforcement costs (in net present value terms). These savings would be associated with around 460MW of additional DG connections nationwide. Moreover, the increase in distribution connected CHP has the potential to deliver up to 3,800 kilotonnes of cumulative reduction in carbon dioxide emissions by 2050 – equivalent to the annual improvement of taking around 800,000 vehicles off the road.
The PowerFul-CB project is funded by the NIC, which is open to applications from UK mainland distribution and transmission networks, including independent network companies, offshore transmission owners and the national system operator. Network companies submit and deliver projects in partnership with the wider energy industry, such as energy suppliers, universities or technology providers.
PowerFul-CB will see ABB deploy the world’s first fault current limiting solution based on compact power electronics. This innovative device will respond to a fault current within 0.35 milliseconds – 300 times faster than a Formula 1 driver – with the added benefit that it can be reset as soon as the fault current is cleared to ensure security of supply.
In the first two years of the project, which started in January 2017, ABB will use its existing 2,000 A power electronic fault current limiter technology to build a full prototype for a trial installation at a primary substation. The aim is to demonstrate its suitability as a smart, cost-effective long term solution for multiple DG connections.
Commenting on the project, Peter Jones, ABB Technology Strategy Manager, said: “Fault currents are a major barrier to the connection of DG. But while a number of smart solutions are already available, they do not meet London’s unique physical and operational constraints in terms of lack of space for new substation equipment and the need to ensure total security of supply. This project will enable us to demonstrate an innovative approach that offers a compact option to achieve a quicker and more cost-effective connection to fault levelconstrained networks.
For more information, please contact:
ABB Power Grids Division UK
Tel: +44 (0)1785 825050
Fax: +44 (0)1785 819019