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Upgrading a commercially-available Fault Current Limiter to a more cost-effective device for enabling additional capacity and improving energy efficiency, by limiting destructive fault currents

Periodic Reporting for period 2 - FCL (Upgrading a commercially-available Fault Current Limiter to a more cost-effective device for enabling additional capacity and improving energy efficiency, by limiting destructive fault currents)

Reporting period: 2016-04-01 to 2017-05-31

Fault currents (or short circuit currents) in electrical networks are unavoidable. Short circuit current levels can be few times and up to many tens of times higher than the normal current levels in the network.
As the complexity of networks increases with growing demand, rapid addition of distributed generation sources and meshing of networks - fault currents increase significantly. If fault current levels increase beyond the capabilities of the network equipment - measures must be taken to reduce these levels.

Saturated core fault current limiters (FCL) are advanced network infrastructure devices used in electrical grids in order to reduce the level of current when a short circuit occurs. Saturated core FCLs are commercially available, reliable and proven devices. GridON's FCLs are particularly attractive to network operators, since they are built using standard transformer technology. Such devices have been operating for several years in Great-Britain with outstanding results both in normal operation and in fault events.

These devices are series connected to the network. They react instantly to fault currents and present high impedance to significantly reduce the fault current level during the entire fault duration. They recover immediately to normal operation once the fault is cleared.

Yet some applications can benefit from increased performance envelope and also from reduced size and mass. Such enhancements can increase the addressable space these devices can cater for, and increase their adoption rate in the market. Specifically - applications such as distributed generation connections and industrial grids - will benefit greatly from such improvements. Requests for distributed generation connection to distribution networks are continuously rising, and very often rejected due fault current headroom, particularly in dense urban areas. Availability of reduced size FCLs would allow such connections to be approved in increasing rates, and in turn contribute to lower electricity prices, improved power quality and network availability and capacity.

This project aims to achieve such enhancements by utilizing auxiliary subsystems that can enable designing saturated core FCLs that are up to 85% lighter than existing ones, while improving their performance envelope.

Such advances will enable offering customers significantly cost reduced devices - and speed up their adoption rate.
As a starting point, specifications were identified for a commercial case of an FCL. Specifications were then written for a scaled-down device as a basis for enhancements. Then specifications were written for devices that would benefit from the enhancements developed in this project. This showed the mass reduction potential of the enhancements.
Conceptual design and preliminary simulations were performed, further affirming the potential of the enhancements, showing the FCLs may be designed much more compact than the baseline technology, up to 85% lighter.
Based on the original project's scope - detailed design was completed, including two improvement directions described in the project proposal. Design reviews were prepared and submitted.
Prototypes have been manufactured and extensive testing was performed, both in GridON's lab and in the Israeli Electric Company short circuit test lab. The tests were successful and proved the directions identified in the project proposal achieved their technology improvement goals.
Following the successful tests, an up-scaled system for commercial applications was designed, as well as an enhanced fault detection system.
The extensive learning accumulated during this project, and in depth assessment of emerging switching-FCL technologies, allowed GridON to further validate its new technology, and assure its fit for use in multiple network configurations.
The progress made in this project has proven the ability to offer significant size and cost reduction of the existing saturated-core FCL technology, while improving its performance envelope.
These improvements can enable much faster adoption of these already well-established products, and allow for significant cost saving in electrical transmission and distribution, as well as in industrial applications, by allowing the continued utilization of fit-for-use equipment, rather than retiring it early.
The improvements developed in this project also enable further reduction of network losses and improved network availability and power quality, as well as inter-connectivity and meshing of grids.
The improved performance envelope allows numerous application to be tapped by this technology, thus enabling the economic design of future networks.
Saturated Core FCL installed in the UK by GridON Ltd.