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1Abstract--The development and testing of an innovative andcompact saturating-reactor High Temperature SuperconductorFault...
2increases proportionally. Figure 2 also shows a representativemagnetic operating point for the HTS FCL during faultcondit...
3IV. THE SECOND FULL-SCALE FCL – THE CEC HTS FCLThe test results from the first HTS FCL encouraged ZEN tobuild a second fu...
4Figure 6 – Measured versus Predicted Voltage Drop (Insertion Impedance)Testing of the CEC HTS FCLFigure 7 – Design Perfor...
5Table 3 shows all four of the Compact HTS FCL prototypesthat were built and tested. These prototypes had the samenominal ...
6Figures 14-16 portray a comparison between calculated andmeasured fault current waveforms for one of the compactprototype...
7Figure 18 – The Simplified 154 KV Transmission Line PSCAD ModelA summary of a possible design of the modeled HTS FCLis pr...
8VII. CONCLUSIONSDesign, testing and application issues of a saturable coreHTS Fault Current Limiter are described. The fi...
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An innovative compact saturable-core HTS Fault Current Limiter - development, testing and application to transmission class networks

The development and testing of an innovative and compact saturating-reactor High Temperature Superconductor Fault Current Limiter (HTS FCL) is described. The development includes an initial dry-type magnetic core design with iron cores partially encircled by an HTS DC coil and a recently completed oil-immersed design with magnetic cores enclosed in a metallic tank placed inside the warm bore of a rectangular HTS DC magnet. The first 15 kV HTS FCL was installed in Southern California Edison’s grid in 2009 and the first transmission-class 138 kV Compact HTS FCL is planned to be in operation in American Electric Power’s grid in 2011.

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An innovative compact saturable-core HTS Fault Current Limiter - development, testing and application to transmission class networks

  1. 1. 1Abstract--The development and testing of an innovative andcompact saturating-reactor High Temperature SuperconductorFault Current Limiter (HTS FCL) is described. Thedevelopment includes an initial dry-type magnetic core designwith iron cores partially encircled by an HTS DC coil and arecently completed oil-immersed design with magnetic coresenclosed in a metallic tank placed inside the warm bore of arectangular HTS DC magnet. The first 15 kV HTS FCL wasinstalled in Southern California Edison’s grid in 2009 and thefirst transmission-class 138 kV Compact HTS FCL is planned tobe in operation in American Electric Power’s grid in 2011.Index Terms--HTS FCL, Fault Current Limiter,Superconducting Coil, Prospective Fault Current, Limited FaultCurrent, Distribution Class FCL, Transmission Class FCL,Saturating Reactor, Saturated-Core FCL.I. INTRODUCTIONSince 2006, Zenergy Power, Inc. (ZEN) has beendeveloping a type of high-temperature superconductor (HTS)fault current limiter (FCL) for electric power grid applications.The HTS FCL employs a magnetically saturating reactorconcept which acts as a variable inductor in an electric circuit.The inductance of the HTS FCL changes instantly in real-timein response to the current in the electrical circuit beingprotected and varies from a low steady-state value ofinductance during normal operating conditions to a high valueof inductance during a fault condition that is sufficient to limitthe fault current to the desired maximum value. HTS faultcurrent limiting concepts have been extensively reported todate [1-5].II. BACKGROUNDFigure 1 is a simplified schematic that shows the basicarrangement of a single-phase ZEN HTS FCL. Referring toFigure 1, one can see that there are two rectangular iron coresarranged side-by-side. The iron cores are surrounded by asingle HTS coil that encircles the adjacent inner limbs of theiron cores in the middle. A small DC power supply energizesthe HTS coil with a DC bias current to create a very strong DCmagnetic field that magnetically biases and saturates the ironcores. Because the DC bias coil is superconducting, very littleenergy is used to magnetically saturate the iron cores.Conventional copper AC coils are wound on the outer limbs ofthe iron cores. The AC coils are connected in series to theelectrical circuit that is to be protected. These AC coils areThis work was supported in part by the California Energy Commission andthe U.S. Department of Energy.F. Moriconi, F. de la Rosa, A. Singh, B. Chen, M. Levitskaya, and A. Nelsonare with Zenergy Power, Inc., South San Francisco, CA, USA.wound in opposite magnetic “sense,” so that during anyparticular one-half cycle of the AC line current, the AC amp-turns from one of the coils are additive to the DC magneticbias field (boost the DC magnetic bias field), while the ACamp-turns from the other coil are opposing the DC magneticbias field (buck the DC magnetic bias field). Using thisarrangement, a single-phase device can be made in which eachof the rectangular iron cores acts independently during eachpositive and negative half-cycle of the AC line current.Figure 1 – The Basic Saturating Reactor HTS FCL Concept DiagramFigure 2 shows a typical B-H curve for the material used inthe iron cores (typically the iron cores are laminated from M-6grain-oriented silicon magnetic steel using overlappingmitered-joint construction techniques common intransformers). Under typical operating conditions, when theDC bias current is on and no AC line current is flowing, theiron cores are magnetically saturated and very strongly biasedinto the upper right-hand quadrant of the B-H curve. Whenthe AC circuit is energized and the AC line current is flowingat normal values, the magnetic operating state of the HTS FCLoscillates over a small range in the extreme upper right-handquadrant of the B-H curve. The AC magnetic flux from theindividual half-phase AC coils alternately “boosts” and“bucks” the DC magnetic bias flux during each positive andnegative half-cycle of the AC line current, but the magneticflux variation and associated losses are very small. Figure 2also shows a representative normal steady-state magneticoperating point for the HTS FCL. Because the slope of the B-H curve is very flat in this extremely magnetically biasedcondition and the oscillations are very small, the impedance ofthe AC coils is a very low value of inductance andapproximates that of an air-core reactor with only a few ACturns (the nominal steady-state AC voltage drop of the HTSFCL is typically 1% or less on a per unit basis).When an AC fault occurs, the AC amp-turns generated bythe AC coils increase linearly with the fault current, and therange of oscillation of the HTS FCL magnetic operating stateFranco Moriconi, Francisco De La Rosa, Senior Member, IEEE, Amandeep Singh, Member, IEEE,Bill Chen, Marina Levitskaya, Albert Nelson, Member, IEEEAn Innovative Compact Saturable-Core HTSFault Current Limiter - Development, Testingand Application to Transmission Class Networks
  2. 2. 2increases proportionally. Figure 2 also shows a representativemagnetic operating point for the HTS FCL during faultconditions in which the magnetic state of the HTS FCL isfluctuating from extreme saturation in the flat, upper right-hand quadrant of the B-H curve down into the steep, nearlyvertical portion of the B-H curve and into lower left-handquadrant of the B-H curve. In this condition the iron cores arealternately magnetically unsaturated by the large excursions inAC magnetic flux, and because the slope of the B-H curve isvery steep and the oscillations in the HTS FCL magneticoperating state are very large, the impedance of the AC coils isa large value of inductance and approximates that of an ironcore reactor.Figure 2– Transition of HTS FCL Magnetic Core States During FaultConditionsFrom the simple schematic in Figure 1, it is easy to envisiona three-phase HTS FCL using a single HTS DC bias coil.Figure 3 shows an arrangement in which three single-phasedevices are arranged radially with their corresponding innercore limbs inside a single cryostat (silver cylinder) containingthe HTS DC bias magnet. The copper AC coils (redcylinders) are located on the outer limbs of the iron cores andspaced equidistantly. This arrangement constituted the basicdesign for the ZEN HTS FCL and was used to construct thefirst two full-scale test devices.Figure 3 – A Three-Phase Saturating Reactor HTS FCL with a Single HTSDC Bias CoilThe essential “technology” of the ZEN HTS FCL is creatingan integrated design that optimizes the performance of the ironcores, the DC HTS magnetic coils and the AC copper coils sothat over the range of expected AC steady-state line currentsthe iron cores remain magnetically saturated and the AC lineimpedance is low, but over the range of expected potential ACfault currents, the iron cores become partially or completelymagnetically unsaturated and the AC line impedance issufficiently high. Since 2006, ZEN has devoted extensiveresources to modeling, simulation, design, manufacture,testing and experimental verification of the predictedperformance of the HTS FCL in order to be able to reliablyand accurately design a magnetically saturating reactor HTSFCL for a specific AC circuit application. As a result of theextensive modeling, simulation and testing (both full-scale andsub-scale) that has been performed over the last three years,ZEN is confident that its HTS FCL technology has beenproven and is ready for commercial deployment.III. THE FIRST FULL-SCALE ZEN HTS FCLThis device was built and tested to verify the basicoperating principles and concepts of the ZEN HTS FCL. Itconsisted of six rectangular iron cores arranged with a singlecryostat in the middle, the six AC coils arranged peripherallyaround the structure, along with the supporting structure andAC electrical bus-work. This device was nominally rated at15 kV and 1,250 amperes RMS (root-mean-square), and wasdesigned to limit an AC fault current by about 15%-20%. TheHTS FCL was manufactured using conventional dry-type (air-insulated) transformer construction techniques for a 110 kVBIL (basic insulation level) rating. The cryostat was an open-loop system using liquid nitrogen, which was replenished asnecessary to compensate for boil-off, and the HTS coil wasconstructed on a G-10 glass reinforced composite structureusing 800 turns of 4-ply BSSCO 1G wire which was suppliedby American Superconductor.The HTS FCL was subjected to full-scale testing first atPacific Gas and Electric’s High-Voltage Test Facility in SanRamon, California in October 2007 and later at BritishColumbia Hydro’s Powertech Laboratories in Surrey, BritishColumbia, Canada in December 2007. The HTS FCL wassubjected to a full-range of testing to determine dielectricperformance, steady-state AC voltage drop (insertionimpedance) under normal operating conditions, and faultlimiting performance, as well as to characterize steady-stateheat loads on the HTS DC coil and in the cryostat, couplingduring steady-state and fault conditions between the AC coilsand the DC coil, and the effects of faults on the HTS coil andthe DC power supplies.Figure 4 shows the typical performance of the first HTSFCL during a fault. During testing of the first FCL atPowertech Laboratories, a total of 54 tests were performed,including 12 AC fault tests.Figure 4 – Typical 16 kA Symmetrical, 37 kA First Peak Fault Test for theFirst Full-Scale HTS FCL. Red is Prospective, Black is Limited Fault Current.100 200 300 400 500 600ms-30-20-10010203040kALineCurrent[kA]-s033ias036ia
  3. 3. 3IV. THE SECOND FULL-SCALE FCL – THE CEC HTS FCLThe test results from the first HTS FCL encouraged ZEN tobuild a second full-scale HTS FCL with the support of theCalifornia Energy Commission (CEC) and the U.S.Department of Energy (DOE). This device, known as theCEC HTS FCL, became the first HTS FCL in commercialservice in the United States on March 6, 2009 when it wasplaced in the Avanti Circuit (otherwise known as the “Circuitof the Future”) in the Southern California Edison (SCE)Company’s Shandin substation in San Bernardino, California.The “Circuit of the Future” is an actual commercial 12.47 kVdistribution circuit with real residential, commercial and light-industrial customers that has been established by SCE, CECand DOE to demonstrate innovative technologies of potentialvalue in the modern electric grid.Figure 5 is a graphic representation of the CEC HTS FCL.The same central HTS DC magnet and radial AC coil generalarrangement was used in the CEC HTS FCL as in the firstfull-scale HTS FCL. There were major differences, however,between the first HTS FCL and the CEC HTS FCL. Amongother things, the CEC HTS FCL employed cast-epoxy ACcoils instead of built-up wound copper coils. The CEC HTSFCL also employed a closed-loop cryogenic cooling systemthat used sub-cooled liquid nitrogen at approximately 68K toincrease the IC and the working current of the DC HTS biasmagnet coil to increase the available DC amp-turns and therange of DC magnetic bias flux. The cryogenic coolingsystem employs two Cryomech® AL300-CP970cryorefrigerators with cold heads located at the top of drip-tubes connected to the liquid nitrogen space of the cryostat.Nitrogen vapor from the liquid nitrogen condenses on thecold-heads, is sub-cooled, and drips back into the liquidnitrogen volume. This recycles the liquid nitrogen andeliminates the need to periodically resupply the CEC HTSFCL with cryogen. The basic design parameters of the CECHTS FCL are shown in Table 1. Because the Avanti Circuit isa newly constructed distribution circuit with a low duty-cycleand no expected fault issues, the CEC HTS FCL was designedfor only modest fault current limiting capabilities and wasintended to limit a 23 kA RMS potential steady-state faultcurrent by about 20%. Instead of fault limiting performance,emphasis was placed on accurately modeling and predictingthe performance of the HTS FCL and its associated electricalwaveforms.Figure 5 – The CEC HTS FCL Graphic RepresentationTable 1 – The CEC FCL Basic Design ParametersThe CEC HTS FCL underwent extensive testing atPowertech Laboratories in October 2008. In the absence of anindustry standard for HTS FCL testing, a comprehensive testplan that incorporated IEEE standards [6-8] for series reactorsand transformers was prepared with input from SCE and theNational Electric Energy Testing, Research and ApplicationsCenter (NEETRAC), a member-financed, non-profit researchlaboratory of the Georgia Technical University (Georgia Tech)in Atlanta, Georgia. Special emphasis was placed oncomparing the performance of the CEC HTS FCL predictedby ZEN’s design protocol with the measured performance ofthe CEC HTS FCL, including AC steady-state current voltagedrop (insertion impedance), steady-state AC currenttemperature rise, AC fault current limiting, and AC coil andDC HTS electromagnetic coupling. The dielectricperformance of the CEC HTS FCL was also tested includingBIL, DC withstand voltage, lightning impulse and chopped-wave testing as required by the applicable IEEE standards [6-8]. Dielectric testing was performed before fault testing, andthen repeated upon the conclusion of fault testing by SCE attheir Westminster, California test facility before installation inthe Avanti Circuit.In all more than 65 separate test events were performed onthe CEC HTS FCL, including 32 fault tests. A typical faulttest sequence involved the application of full-load steady-statecurrent and voltage (1,250 amperes RMS at 13.1 kV), theapplication of 30-cycles or more of fault current up to nearly60 kA first-peak, and returning to the full-load conditionsupon clearance of the fault. The CEC HTS FCL performedextremely well and exceeded expectations by withstandingmore than an expected lifetime of actual faults during a weekof testing. Figure 6 shows a typical insertion impedance testfor the CEC HTS FCL. Notice the excellent match betweenthe predicted and the measured voltage drop as a function ofAC steady-state current. Figure 7 shows a typical faultsequence test in which the AC fault current is limited byapproximately the targeted 20% reduction level. Figure 8 isan endurance test of the CEC HTS FCL in which it wassubjected to an 82-cycle fault, and Figure 9 is a double-faultsequence test, which was performed to measure the CEC HTSFCL performance under an automatic re-closer scenario.Figure 10 shows the CEC HTS FCL in the Avanti Circuit atSCE’s Shandin substation, where it remained as of November2009.
  4. 4. 4Figure 6 – Measured versus Predicted Voltage Drop (Insertion Impedance)Testing of the CEC HTS FCLFigure 7 – Design Performance Verification Test for the CEC FCLFigure 8 – 82-Cycle Endurance Fault Test of the CEC FCLFigure 9 – A Double-Fault Sequence Simulating Re-Closer Operation on theCEC FCLFigure 10 – The CEC FCL Installed at the SCE Shandin Substation in SanBernardino, CaliforniaV. THE INNOVATIVE COMPACT HTS FCLIn the course of building and testing the CEC HTS FCL,ZEN conceived a new concept for saturating reactor HTS FLCdesign that had the potential to considerably reduce the sizeand weight of the device, while allowing the dielectric ratingof the HTS FCL to be increased to transmission voltages of100 kV and higher. This concept became known as the“Compact HTS FCL,” and in order to test the concept andevaluate alternative methods for implementing it, ZEN, withfinancial support from the U.S. Dept. of Energy, built andtested four full-scale prototypes using different internaldesigns.All of the Compact HTS FCL prototypes were built usingstandard “oil-filled” liquid dielectric transformer constructiontechniques. This allowed the minimum required dielectricoffset distances within the HTS FCL to be minimized, greatlyreducing the HTS FCL prototypes’ size and weight forequivalent performance. Table 2 shows a comparison betweena “dry-type” HTS FCL using the original radial AC coildesign and an “oil-filled” Compact HTS FCL of equivalentdesigned performance. Both of the HTS FCLs are 26 kV, 2kA steady-state current devices designed to limit a prospective30 kA symmetrical fault with a 1.6 asymmetry factor by 50%.The Compact HTS FCL requires only 28.4% of the volumeand has only 26.6% of the iron core mass of the originaldesign. Another important design innovation was the use of“dry-type” cryogenics to conductively cool the HTS coilwithout the use of liquid cryogens. This allowed the operatingtemperature of the HTS coils to be reduced below the freezingtemperature of liquid nitrogen, enabling further increases inthe IC and working current of the 1G HTS wire used in the DCbias magnet system and correspondingly higher DC amp-turnsto magnetically saturate the iron cores. The use of conductioncooling also removes potential utility concerns about havinglarge volumes of liquid cryogens in confined spaces andpotential pressure vessel over-pressurization, rupture andventing concerns.Parameter Old Design New DesignIron Core Weight(lbs)252K 67KCost of Iron@ $3/lb$ 756K $ 201KFCL Size (core iron +AC coils19 x 19 10 x 7Table 2 – Comparison of Radial AC Coil (Old Design) and Compact (NewDesign) HTS FCLs0.5 1 1.5 2-50-40-30-20-1001020304050TEST 77 - 1.25s - 80 cycles FAULT - 20kA X/R=22, FCL INTime [sec]LineCurrent[kA]Phase APhase BPhase C0.5 1 1.5 2 2.5 3 3.5 4-50-40-30-20-1001020304050TEST 77 - DOUBLE FAULT SEQUENCE - 20kA X/R=22, FCL INTime [sec]LineCurrent[kA]Phase APhase BPhase C
  5. 5. 5Table 3 shows all four of the Compact HTS FCL prototypesthat were built and tested. These prototypes had the samenominal 15 kV design voltage and 110 BIL rating, but differedin their steady-state AC current ratings and targeted ACsteady-state current insertion impedance and AC fault currentlimiting performance. The designed AC steady-state currentlevels ranged from 1,250 amperes RMS to 2,500 amperesRMS, and the targeted AC fault current reduction levelsranged from about 30% up to more than 50% of a 25 kA RMSpotential steady-state fault current with an asymmetry factoryielding a first-peak fault current approaching 50 kA.The Compact HTS FCL prototypes underwent full-powerload and fault testing at Powertech Laboratories in July 2009using essentially the same comprehensive test plan that wasemployed for the CEC HTS FCL. In all 118 separate testswere performed on the four Compact HTS FCL prototypes,including 55 calibration tests, 12 load current only tests, and51 fault tests. In many cases, the measured performanceexceeded expectations, and the test program completelyvalidated both the performance potential of the Compact HTSFCL design and the efficacy of ZEN’s design protocol. Figure11 shows an illustration of one of the compact HTS FCLprototypes.Figure 12 shows the results of a typical AC load currentvoltage drop or insertion impedance test which displays goodagreement between the predicted and the measuredperformance. Figure 13 shows a fault current test in which theCompact HTS FCL prototype reduced a prospective 25 kARMS fault current with a 1.6 asymmetry factor by about 46%.Parameter Units FCL #1FCL #2FCL #3FCL #4Line-to-Line Voltage kV 12.47 12.47 12.47 13.8Number of Phases # 3 3 1 1Line Frequency Hz 60 60 60 60Prospective FaultCurrentkA 35 46 80 25Limited Peak Fault kA 27 30 40 18Prospective FaultCurrent RMSSymmetricalkA 20 20 40 11Limited SymmetricFault CurrentkA 15 11.5 18 6.5Load Current Steady-State RMSkA 1.25 1.25 1.25 2.5 –4.0Voltage Drop Steady-State Maximum% 1 1 1 2Line-to-GroundVoltagekV 6.9 6.9 6.9 8.0Asymmetry Factor # 1.2 1.6 1.4 1.6Source FaultImpedanceOhms 0.346 0.346 0.173 0.724Fault Reduction % 25 43 55 41Table 3 – The Four Full-Scale Compact HTS FCL Devices Tested atPowertech Laboratories July 2009Figure 11 – Compact ZEN 12 kV HTS FCL undergoing testing at PowertechHigh Power LaboratoryFigure 12 – Typical AC Steady-State Load Current Voltage Drop (InsertionImpedance) MeasurementsFigure 13 – Compact FCL Fault Test at Powertech Laboratories July 2009.The black curve is the prospective fault current, the red curve is the limitedfault current, and the blue curve is the voltage measured at the FCL terminals
  6. 6. 6Figures 14-16 portray a comparison between calculated andmeasured fault current waveforms for one of the compactprototypes under a 15kA symmetric fault to ground condition.Figure 14 - Measured vs. Calculated 15kA Prospective and Limited FaultCurrentFigure 15 - Measured vs. Calculated Back EMF for 15kA Fault LevelFigure 16 - Measured vs. Calculated Voltage Drop for 1.1kA Load CurrentA particularly important result from the Compact HTS FCLtesting program was the fact that the AC coils and the DCHTS Coil exhibited very little electromagnetic coupling.Figure 17 shows that the DC current in the HTS bias coilvaried only about 5% as the Compact HTS FCL was subjectedto up to a 30 kA peak fault current. These results were verytypical for all of the Compact HTS FCL devices during faultcurrent testing. The steady-state voltage drop (insertionimpedance) of the Compact HTS FCL typically remained lowwith increasing AC currents and also exhibited very “clean”AC power characteristics with Total Harmonic Distortionlevels well within the requirements of IEEE 519-1992 [9].Figure 17 – AC Coil and DC HTS Coil Electromagnetic Coupling during ACFault Current TestingVI. A COMPACT HTS FCL DESIGN FOR TRANSMISSION CLASSAPPLICATIONSAs a result of the successful testing of the Compact HTSFCL prototype, ZEN has initiated the commercial sale of theCompact HTS FCL for medium-voltage applications. Also,ZEN has entered into an agreement with American ElectricPower (AEP), Columbus, Ohio, to partner for thedemonstration of a 138 kV three-phase Compact HTS FCL asa part of ZEN’s ongoing DOE-sponsored HTS FCLdevelopment program. A single-phase 138 kV Compact HTSFCL prototype will be built and tested in 2010, and a three-phase Compact HTS FCL demonstration unit will be built,tested and installed in AEP’s Tidd substation located nearSteubenville, Ohio in 2011.ZEN has considered a potential application for a “typical”154 kV transmission application in an Asian electric powergrid. The design approach taken was for a device with arelatively modest level of fault current reduction and a lowvalue of steady-state voltage drop (insertion impedance).Figure 18 shows the simplified transmission line one-linediagram PSCAD model that ZEN created to represent a“typical” 154 kV transmission line. The voltage sourceparameters with the corresponding line impedances are shownon the left-hand side of the diagram, and a single lumped loadis shown on the right-hand side of the diagram along with the“Timed Fault Logic.” The FCL is located in the middle of thediagram, and the graphical representation of the HTS FCLmodel that is inserted into the circuit is shown in Figure 19.Figure 20 shows the prospective fault current with the FCLbypassed and a 2,000 amp load current bypassing the FCL. Inthis scenario, the prospective first peak asymmetric faultcurrent is 103 kA and the prospective symmetrical faultcurrent is 40 kA. Figure 21 shows the resulting limited faultcurrent under the same scenario as Figure 18, but with theHTS FCL in the circuit instead of being bypassed. In thisscenario, the limited first peak of the fault current is 75 kA (a28% reduction) and the limited symmetrical fault current is24.8 kA (a 38% reduction), and the normal steady-statevoltage drop (insertion impedance) with a 2,000 amp loadcurrent through the HTS FCL is 1.0% or about 890 volts (thisvoltage drop is proportional to the load current and is lessunder lighter loads).0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75-20-15-10-5051015202530Test 97 - ZENERGYPOWER Compact FCL - 15kA Prospective Fault - 120A DC BiasTime [sec]LineCurrent[kA]MEASURED LIMITEDMEASURED PROSPECTIVEMODEL LIMITED0.53 0.54 0.55 0.56 0.57 0.58 0.59 0.6 0.61 0.62-5-4-3-2-1012345Test 97 - ZENERGYPOWER Compact FCL - 15kA Prospective Fault - 120A DC BiasTime [sec]FCLBACKEMF[kV]MEASUREDMODEL0.18 0.2 0.22 0.24 0.26 0.28 0.3 0.32-0.15-0.1-0.0500.050.10.15Test 97 - ZENERGYPOWER Compact FCL - 15kA Prospective Fault - 120A DC BiasTime [sec]FCLBACKEMF[kV]MEASUREDMODEL
  7. 7. 7Figure 18 – The Simplified 154 KV Transmission Line PSCAD ModelA summary of a possible design of the modeled HTS FCLis presented in Table 4. Each phase of the three-phase HTSFCL would be about 1.5 meters in diameter and about 7meters long. Using a horizontal orientation, it would fit in afootprint about 5 m x 7 m x 4 m.Figure 19– The 154 kV HTS FCL Model for PSCAD AnalysisFigure 20 – The Prospective Fault Current in the 154 kV Circuit without theHTS FCLFigure 21– The Fault Currents in the 154 kV Circuit with the HTS FCLAgain, it is important to understand that while this is anHTS FCL design that could be manufactured today and whichZEN is confident would work as modeled, it is not the onlypossible design and other potential HTS FCL devices ofdifferent sizes, orientations and performance can also bedesigned and manufactured. For example, an HTS FCL with alower steady-state voltage drop could be built, if a longerdevice were acceptable. If desired, the fault limitingperformance of the HTS FCL could also be increased byincreasing the diameter and length of the device.154 kV Single-Phase FCL Parameters Units ValueLine-to Line Voltage kV 154Line Frequency Hz 60Rated Current Amperes 2,000Asymmetry Factor # 2Base Power MVA 100Maximum Allowable Voltage Drop Percent ofLine Voltage% 2Line-to-Ground Voltage kV 89FCL Fault Impedance Ohms 2Steady-State FCL Allowable Inductance µH 1,698Maximum Induced EMF for Desired Fault CurrentLimitingkV 44Maximum De-Saturation Flux Change Tesla 4Steady-State FCL Maximum Allowable Impedance Ohms 1Coil Height Meters 5Core Height Meters 7Core Weight Kg 48,912HTS Wire Length Meters 37,762NI HTS Coil Amp-Turns730,000Overall FCL Width Oriented Horizontally (three,single-phases in array)Meters 5Overall FCL Length Oriented Horizontally (three,single-phases in array)Meters 7Overall FCL Height Oriented Horizontally (three,single-phases in array)Meters 4Table 4 – The 154 kV HTS FCL Basic Design ParametersR=0Line LoadFCL0.12485 [ohm]5.8868e-3 [H]BRK1293.6 [MVAR]485.4 [MW]154 kV ACSource453 [MW] 281 [MVAR]EaABC->GTimedFaultLogic
  8. 8. 8VII. CONCLUSIONSDesign, testing and application issues of a saturable coreHTS Fault Current Limiter are described. The first in its class15 kV FCL prototype sponsored by the California EnergyCommission and the US Department of Energy has alreadybeen put in operation at Southern California Edison. Four 15kV compact design prototypes have been successfully tested.Based on this, design and testing of commercial HTS FCLdevices has been initiated, including a single phase 138 kVcompact design prototype and a compact three-phasedemonstration unit will be installed in an American ElectricPower substation in Ohio in 2011.VIII. REFERENCES[1] Schmitt, H., Amon, J. Braun,D., Damstra, G., Hartung, K-H, Jager, J.,Kida, J, Kunde, K., Le, Q., Martini, L., Steurer, M., Umbricht, Ch,Waymel, X, and Neumann, C., “Fault Current Limiters – Applications,Principles and Experience”, CIGRE WG A3.16, CIGRE SC A3&B3Joint Colloquium in Tokyo, 2005[2] CIGRE Working Group, “Guideline of the impacts of Fault CurrentLimiting Devices on Protection Systems”. CIGRE publishing, VolA3.16, February 2008. Standard FCL and Cigre[3] CIGRE Working Group, “Fault Current Limiters in Electrical mediumand high voltage systems”. GIGRE publishing, Vol A3.10, December2003.[4] Noe. M, Eckroad. S, Adapa. R, “Progress on the R&D of Fault CurrentLimiters for Utility Applications,” in Conf. Rec. 2008 IEEE Int. ConfPower and Energy Society General Meeting pp.1-2.[5] Orpe, S. and Nirmal-Kummar, C.Nair, “State of Art of Fault CurrentLimiters and their Impact on Overcurrent Protection”, EEA ApexNorthern Summit 08, November 2008, Power Systems Research Group,The University of Auckland[6] IEEE Std C57.16-1996; IEEE Standard Requirements, Terminology,and Test Code for Dry-Type Air-core Series-Connected Reactors.[7] IEEE Std C57-12.01-2005: IEEE Standard General Requirements forDry-Type Distribution and Power Transformers, Including Those withSolid-Cast and/or Resin Encapsulated Windings[8] IEEE Standard Test Code for Liquid-Immersed Distribution, Power andRegulating Transformers”, IIEEE Std. C57.12.90-1999.[9] ANSI/IEEE 519-1992, “Recommended Practices and Requirements forHarmonic Control In Electric Power Systems”, ANSI/IEEE StandardsIX. BIOGRAPHIESFranco Moriconi leads Zenergy Power’sEngineering effort in the development of acommercial Superconducting Fault Current Limiter.Under his technical leadership Zenergy Powerinstalled and energized a first-ever HTS FCL in theUS electric grid. In 1992, he joined ABB CorporateResearch to lead R&D work in the areas of numericaland Finite Elements methods, short-circuit strengthand noise reduction of power transformers, GasInsulated Switchgear technology, and high-speedelectrical motors and generators. He also participated in two IEC workinggroups, and was the Convener of the IEC Scientific Committee 17C onseismic qualification of GIS. Currently, he is an active member of the IEEETask Force on FCL Testing. Franco Moriconi earned a Bachelor of Sciencedegree and a Master of Science degree in Mechanical Engineering from UCBerkeley. He is the co-author of six patents in the field of HV and MVelectrical machines.Amandeep Singh has led the in-depthunderstanding of FCL action in Zenergy Power sincejoining in January 2008 and has been instrumental inthe modeling of the first-ever HTS FCL installed inUS grid. He holds a Bachelor of Electronics &Telecommunications degree from GNDEC,Ludhiana (Punjab). He has worked as SeniorExecutive Engineer for ten years in utility generation(plant control systems), transmission (sub-stationO&M) and distribution (planning, augmentation,metering and revenue) sectors. He has an EIT in the State of California and ispursuing a professional engineer’s registration. He is a member of IEEE.Francisco De La Rosa joined Zenergy Power Inc. inApril 2008 as Director of Electrical Engineering.Before joining Zenergy Power, Inc., Francisco hadheld various positions in R&D, consultancy andtraining in the electric power industry for around 30years. Francisco holds a PhD degree in ElectricalEngineering from Uppsala University, Sweden. He isa Collective Member of CIGRE and a Senior Memberof IEEE PES where he contributes in several WG’sincluding the TF on FCL Testing. . .His maininterests include the assessment and integration of new technologies in theelectric power system.Bill Chen joined Zenergy Power Inc. in August of2009, but has worked as a consultant since Februaryof 2007. While still adapting to the power industry,Bill has been involved in the development andautomation of HTS FCL prototype along with theautomation of the data acquisition equipment. Hehas enjoyed using his skill set across multipleapplications, from data acquisition, PACPLCprogramming, data storage and trending, userinterface development, and project management.Bill holds a bachelors degree in computer sciencefrom the University of Texas, along with certifications in variousprogramming languages.Marina Levitskaya joined Zenergy Power, Inc. inSeptember 2008 and has been instrumental in themechanical design of the first HTS FCL unit thatwas successfully tested and installed in US grid. Sheearned a Bachelor of Civil Engineering degree fromVSUACE, Volgograd, Russia. Her workingexperience combines six years of the successfulHVAC design for commercial projects in Russia andfour years of various mechanical designs in the US.Albert Nelson has been COO of Zenergy Power,Inc. since its founding in 2006. Prior to joiningZenergy Power, Inc., he was a cofounder of DirectDrive Systems, Inc., a manufacturer of high-speedmotors and generators, and Cheng Power Systems,Inc., a developer of technologies and systems toimprove the efficiency, increase the power outputand reduce the emissions of combustion turbines.From 1991 to 1999, he was Director of ProjectFinance for Raytheon Engineers and Constructors,Inc. and Manager of Special Projects and Technology Development forRaytheon Systems Nevada, Inc. at the U.S. Department of Energy NevadaTest Site. Mr. Nelson retired from the U.S. Navy Submarine Service as aCommander

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