Utilities Speak For Themselves

US

Every utility is different, but many of them recognize the needs identified by P.M. Duggan on behalf of New York City’s utility, Consolidated Edison. In a presentation1 to the IEEE, Duggan wrote

      Con Edison believes that additional fault current sources will be added and that new more flexible solutions are needed. Fault currents could be increased in the future by:
      • an increase in market based transmission development,
      • increased penetration of distributed generators and/or
      • the addition of very low impedance superconducting cables.
      In addition, energy storage devices will be needed to take advantage of renewable energy sources that are wind or sunshine dependent and to improve asset utilization but they also can add to fault currents.
      For the above reasons alone fault current limiters (FCLs) are needed so that total rebuild of the existing system will not be required in addition to construction supporting new capacity.

    China

    Nor is this only a US need. A recent review2of the situation in China by staff from InnoPower and the Yunnan Power Grid Co. states that
        In 2009, State Grid Corporation of China (SGCC) put forward a plan to promote the development of a robust and efficient power grid. During the power grid modernization process, along with the enlargement of the scale, the connections of power grids become tighter and short-circuit current levels, higher. At places, short-circuit currents are near or over the breaking capacity of circuit breakers, making short-circuit current control increasingly important. Besides enhancing system optimization, effective fault current limiting hardware such as SFCL [Superconducting Fault Current Limiters] will also provide meaningful options for utilities and hence has great market potentials…
        Solutions to fault current include the following measures: increasing the current allowance capacity of switching devices and other equipment; breaking off operations and introducing higher voltage connection circuits; and adopting transformers with higher impedance and/or sequentially connecting inductive impedance devices. However, each of these measures creates its own problems. For example, breaking off operation reduces grid reliability, and higher impedance transformers increase energy loss, thus negatively impacting the quality of the grid's power supply.
        Compared with existing conventional limiting devices, SFCLs have many advantages: very low impedance during normal power transmission, resulting in an exceptionally low voltage drop on the device and very low transmission losses; adequate current limiting performance; rapid detection and initiation of limiting action; and fast recovery to normal operation after the clearing of a fault. When used in several interconnected systems, SFCLs can help form a stable power grid, ensuring that a system failure will not affect the normal operation of the entire grid, thus improving system reliability. This feature meets energy-saving, safe, robust and efficient grid needs. SFCLs can be applied to a wide range of power networks and can be designed specifically for different applications in order to achieve the best technical and economic impact.

    Korea

    Much more terse is The Korean Electric Power Research Institute (KEPRI), an arm of the Korean Electric Power Company (KEPCO). At the EUCAS 2011, KEPRI presented the following statement.

    United Kingdom

    While KEPRI is addressing a present problem, the UK’s Energy Technologies Institute LLP (the ETI) – a private organisation formed as an innovative Limited Liability Partnership between international industrial energy companies and the UK government – addressing the near future. The ETI states that its mission is to accelerate the development, demonstration and eventual commercial deployment of a focused portfolio of energy technologies, which will increase energy efficiency, reduce greenhouse gas emissions and help achieve energy and climate change goals. After reviewing off-the-shelf technologies for coping with the UK’s increasing fault currents, ETI wrote that
        These ‘passive’ techniques have the disadvantage of introducing considerable additional cost and can have a negative impact on operational complexity, power quality, power system stability, reliability and security of supply. A significant number of new DG projects do not proceed as a consequence, and fault current levels are becoming a major barrier to DG installation.

        New ‘active’ Fault Current Limiter (FCL) technologies, involving devices which normally have a low impedance but which can increase impedance when fault current flows, have the potential to provide a more flexible and lower cost solution to this issue. However, these require accelerated further technology development and demonstration before being suitable for UK applications.

        FCL technologies would also facilitate efficient network operation, reducing power losses by enabling more efficient interconnection, increasing flexibility in the configuration and operation of the network, and increasing capacity and security of supply.

        …The ETI’s highest priority for initial application of FCL technology is on the UK’s electricity distribution networks at 11kV, with the objective of expanding the technology capability thereafter to be applied also at 33kV.


    1P. M. Duggan, Senior Member, IEEE, Utility Perspective on Fault Current Limiters and Expected Synergies from Integrating Fault Current Limiters with Superconducting Cables, IEEE 2008
    2    Z.L. Chen, W.Z. Gong, A.L. Ren, M.R. Zi, Z.Q. Xiong, D.J. Si, and F. Ye, Prospective of Applications of Superconducting Fault Current Limiters in Chinese Power Grids, EUCAS 2011