Fault Current Limiters and Energyoffice Ofelectricitydelivery Reliability Operation Whichallows Foramore Stablesystem

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Fault Current Limiters and EnergyOffice ofElectricityDelivery Reliability operation whichallows foramore stablesystem. ers, FCLsoperatewithlittleto noimpedanceduringnormal ance transformers.However, incontrasttothesetransform levels increase the need for larger and often costly high imped overcome theseweaknesses. Additionally, risingfaultcurrent losses, are bulky, andcontributetogridvoltage drops. FCLs reactors are alsousedbuttheyhave constant highreactive and theyare only available forvoltages below 35 kV. Series but theyrequire calltoreplace thefuseafteritblows aservice explosive fault-limiting fusesare utilized tolimitfaultcurrent, are addedtoanalready overburdened system.Currently, generation andcleanenergysources, suchaswindandsolar, levels asenergy demandincreases andmore distributed The needforFCLsisdriven by risingsystemfaultcurrent W high-temperature superconducting andsolid-state. categories ofFCLtechnologiesexist: hold devices.Currently, twobroad limit damagingcurrents tohouse similar tothewaysurgeprotectors operation oftheelectricalsystem, for thecontinual,uninterrupted ing through thesystemandallows limits theamountofcurrent flow fuse. Afaultcurrent limiter(FCL) tripped circuit breaker orablown section ofthatsystemby causinga often resulting inafailure ofone flows through theelectricalsystem current—called faultcurrent— faults. During afault,excessive lines, orcrossed power linescause such aslightning,downed power electric circuit. Avariety offactors inan short-circuit, circuit, orpartial A faultisanunintentionalshort W T hy hat ypes Solid-state FCLsuse high-speedsolid-stateswitching High-temperature superconducting (HTS) FCLsuse into thecircuit tolimitthefaultcurrent. devices to rapidly insert an energy absorbing impedance impedance intothepathoffaultcurrent. currents by introducing alarger-than-normal superconducting-based materialandreduce fault

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need a ul s t ? FCL C urrent s ? Office of Electricity Delivery andEnergy Reliability, Delivery Office of Electricity OE-1 L FCLs are a supporting technology in the Smart Grid. technology intheSmart FCLs areasupporting Plugging AmericaIntotheFutureofPower imiters - - effect utilitytransmissionanddistributionequipment,preventingdamage. During a ground fault, an FCL safely mitigates the excess energy that would normally

- installing FCLs.Other benefitsinclude: Utilities canreduce oreliminatethesereplacement costsby breakers andotherexpensive T&D systemcomponents. currents. These largecurrents candamageordegradecircuit tain andprotect thegridfrom fault potentiallydestructive stance, utilitiesspendmillionsofdollarseachyear tomain FCLs offernumerous benefitstoelectricutilities. For in W hat resetting components added totheelectricgrid costly replacement electrical surgesthatdegradeequipmentandrequire downstream T&D systemequipmentfrom constant dooccur disruptions andincreasedlocalized disruptions, recovery timewhen power systems delivery Single tomultipleshot(fault)protection plusautomatic Reduced voltage dipscaused by highresistive system Elimination ofsplitbusesandopeningbus-tiebreakers Improved systemreliability whenrenewables andDGare Reduced maintenance costsby protecting expensive Reduced oreliminated wide-area blackouts,reduced Enhanced systemsafety, stability, andefficiencyofthe A Solid-state PowerEquipment re

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to U tilities Phone: 202-586-1411 ? - - AMSC’s Team Includes: FCL Projects • Southern California Edison The Office of Electricity Delivery and Energy Reliability is funding three HTS FCL projects carried SuperPower, • Nexans out by American Superconductor, Zenergy Power, Inc. • the University of Houston Inc., and SuperPower, Inc. It is also funding one SuperPower will design, • Los Alamos National Laboratory solid-state FCL project led by the Electric Power test, and demonstrate, on • Siemens AG Research Institute (EPRI). the American Electric Power grid, a 138-kilovolt resistive HTS Zenergy Power’s Team HTS Fault Current Limiters FCL that features a matrix design. Includes: The HTS fault current limiter projects currently This design consists of parallel 2G HTS • DOE’s Los Alamos National underway are either resistive or inductive. elements and conventional copper coils. By Laboratory In a resistive HTS FCL, the HTS material absorbs using a cold shunt coil, no external or ancillary • American Electric Power the fault current by quickly switching the HTS components or equipment are required; the device • Southern California Edison Inc. material from a superconducting state to a highly is self-contained. Operational feasibility is expected to • Zenergy Power GmbH resistive state, which then limits the fault current. be made possible by SuperPower’s 2G HTS material, • Zenergy Power Pty Ltd. This transition occurs automatically and triggers which has a very rapid response time (~0.5ms) and the current to transfer into a current limiting coil enables the device to recover to the superconducting or reactor. state while carrying load current from other (non- SuperPower’s Team Includes: In an inductive HTS FCL, the large fault faulted) lines. • Sumitomo Electric Industries Ltd. current desaturates the iron core of the series AC • Nissan Electric Co. Ltd. coils and the increased reactance limits the fault American Superconductor • DOE’s Los Alamos National current. American Superconductor (AMSC) is addressing Laboratory the development and in-grid testing of a three- • American Electric Power Solid-State Fault Current Limiters phase, high-voltage, 138-kilovolt resistive HTS • DOE’s Oak Ridge National This type of limiter switches power into an energy FCL called a SuperLimiter™, which uses second Laboratory absorber within a few microseconds of a fault current, generation (2G) wire. The SuperLimiter™ features preventing the onset of damaging current from reach- a proprietary Siemens-developed, low inductance EPRI’s Team Includes: ing utility assets, such as circuit breakers. coil technology that makes the FCL invisible to the grid until it switches to a resistive state. The design • Silicon Power Corporation Zenergy Power, Inc. uses high voltage components developed by Nexans and demonstrated on the DOE-funded LIPA cable Contact Information: Zenergy Power will design, test, and demonstrate project. AMSC is employing resistive FCLs because AMSC FCL: Walter Romanosky a 138- kilovolt transmission class inductive HTS they are expected to be simpler and more compact in (978) 842-3000 FCL. In this type of FCL, a high-temperature design. [email protected] superconductor is used with a direct current (DC) power supply to saturate an iron core series reactor EPRI SuperPower FCL: in-line with the current that is to be limited. In this Juan Carlos Llambes device, the AC line current of the power grid is always DOE awarded a contract to EPRI to develop a (518) 346-1414 carried by conventional copper conductors formed 69-kVclass solid-state current limiter (SSCL), slated [email protected] into AC coils. The HTS material is used only to form to be delivered in 2009. Working as a subcontractor, Silicon Power Corporation in Malvern, Pennsylvania, Zenergy FCL: Larry Masur a very strong electromagnet—the DC coil—that saturates an iron core inside the AC coils with a DC is developing the SSCL, which uses super gate turnoff (781) 738-8501 thyristor (SGTO) semiconductor switches to rapidly [email protected] magnetic flux. The Zenergy device is referred to as a “saturable reactor.” It is the large AC fault current that switch the SSCL from a low-impedance state to a higher EPRI: Ashok Sundaram drives the AC iron core out of saturation – increasing impedance state. The goal is to build and test several (650) 855-2304 the AC reactance and thereby limiting the current that smaller-scale devices, leading up to a 69- kilovolt, 1000- [email protected] flows in the power grid and acts as an “auto-reactor”. amp, single-phase SSCL, which will look much like a transformer and will be cooled internally by a circulated cooling fluid. DOE Program: Debbie Haught, DOE (202) 586-2211 [email protected]

Zenergy fault current limiter operating in Southern California Edison’s Avanti Circuit

Revision Date: 11/06/09