Distribu}on System Coordina}on Using WindMil / Light Table

Jim Cross, PE Planning Engineer Homer Electric Associa(on, Inc. Kenai, AK Distribu(on System Coordina(on Using WindMil / Light Table Outline
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Define topic What can WindMil do? What can LightTable do? What can WindMil + LightTable do? Case Study Topic •  Designing or improving a scheme of over-­‐current devices to protect your power system from the majority of expected fault condi(ons. •  Available technology versus u(lity preferences versus economics. •  Realize there is as much “art” to this as science. •  There is no such thing as “perfect”, and there are likely to be mul(ple schemes that will work. System Coordina(on Guidelines •  Have a living document that outlines philosophy and goals of your distribu(on system protec(on. •  Make sure all affected departments (Engineering, Opera(ons, etc.) buy in on the guidelines. •  Remember the art versus science aspect. •  It’s a guideline … expect cases where you will have to make excep(ons. Outline • 
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Define topic What can WindMil do? What can LightTable do? What can WindMil + LightTable do? Case Study Terminology •  Device pair – two protec(ve devices that are in series with each other. The upstream device, or the one closer to the sub is o]en referred to as the protected device. The downstream device, or the one farther from the sub is o]en referred to as the protec(ng device. Terminology •  Coordina(on point – intersec(on of two TCC curves that determines the “limit of coordina(on” between two protec(ve devices. •  If you are using fuses from a single vendor & family, vendors can o]en provide. Limit of Coordina(on Chart PROTECTING DEVICE 65T 65T PROTEC
TED DEVICE 65E-­‐vs 40T 40E-­‐s 25T 25E-­‐std 10T 10E-­‐std * * 2273 1326 3400 1731 3823 2459 65E-­‐vs * * 1810 1150 3123 1572 3579 2281 1535 814 2352 1420 40T * * * * 40E-­‐s * * * * * * 1803 1076 25T * * * * * * 1334 789 25E-­‐std * * * * * * 703 437 * * * * * * * * 10E-­‐std * * * * * * * * 10T NOTES All fuses are S&C All values are available fault current in amps "75% Rule" states protected fuse minimum melt curve mul(plied by 0.75 (me factor WindMil Tools – Fault Current Calcula(ons •  Determine the levels of fault current that are available on various parts of your system. •  Model different fault types •  Maximum and minimum fault levels. •  One needs to set-­‐up informa(on in the SOURCE elements for this to work properly. •  Good Z data for lines, XFMRs, etc. •  Calculate faults for each element down-­‐line of the SOURCE element. Seqng Up a SOURCE element Obtain fault data from your transmission provider. Seqng Up a SOURCE element Since we have modeled the source at the transmission level, we can simply enter the fault data here. Seqng Up a SOURCE element In the case where you do not have the substa(on XFMR modeled, you can enter it here. This will shi] the fault reference data to the XFMR low side. Running Fault Current Analysis •  Turn on circuit(s) you want to analyze •  Select “Fault Current” and run. •  Radial analysis goes quickly, looped analysis can take a few minutes. Fault Current Seqngs This is the less controversial set of op(ons. What to include, voltage op(ons, etc. Fault Current Seqngs “Minimum fault current method” may be one of the most controversial discussed topics in our industry. Minimum Fault Methods Two generally accepted methods: •  Constant Ohm Z (a.k.a. the 40 Ohm Rule) •  Percent (some reasonable % of the bolted fault (max) current Which one do I use, and what numbers??? Minimum Fault Methods •  This ques(on alone merits having a company-­‐
accepted set of coordina(on standards. •  Don’t blindly follow 40 Ω Rule. •  Do what is best for your u(lity’s unique situa(on. Fault Current Calcula(ons – Bench-­‐marking With all of the new relays and meters that are capable of event / waveform capture, it’s very easy to bench-­‐mark model calcula(ons against real system faults.
A single fault on a quiet day is bever than trying to correlate events and loca(ons from a storm event. Obtain addi(onal info from Opera(ons / crews (loca(on, cause, etc.) Coordina(on Analysis •  This analysis will systema(cally go thru selected protec(ve devices and checks seqngs against a set of rules. There are some default industry standards built-­‐in, but most are user configurable. Coordina(on Analysis Seqngs •  Unbalanced or balanced voltage drop? •  Coordina(on points? (next slide) •  Recalculate coordina(on points for each itera(on of Coordina(on Analysis? •  Default is all device pairs. If using manually set coordina(on points, pick the lower op(on. Seqng Coordina(on Points Manually This is where one defines the upline (protected) devices for each device in your Equipment List. If using Light Table devices, this is done automa(cally. Coordina(on Analysis Results from voltage drop analysis are compared to the Con(nuous Current Seqngs for each protec(ve device. The Con(nuous Current Seqngs compare the current ra(ng of a device to the normal load current going through it. The mul(pliers are used to change the amount of load each device compares to. A lower mul(plier can be used to cushion for future load growth. Coordina(on Analysis The Maximum Fault Test will compare the calculated maximum fault current at each device loca(on to the manufacturer’s recommended maximum fault current ra(ng (as defined in LightTable) at that loca(on (mes a mul(plying factor. The Maximum Fault Test will fail if the calculated fault is greater than the fault ra(ng (mes the mul(plying factor. Coordina(on Analysis The Minimum Pickup Test, performed during Coordina(on Analysis, will compare the calculated minimum fault current down-­‐line from each device loca(on to the manufacturer’s recommended minimum pickup ra(ng of the device (defined in LightTable) (mes a mul(plying factor. The Minimum Pickup Test will fail if the calculated minimum fault is less than the ra(ng (mes the mul(plying factor. Coordina(on Analysis Seqngs The Coordina(on Test will check for correct coordina(on between each device and its upline device. The test method and required data are dependent on the type of device and the type of the protected (upline) device. Outline • 
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Define topic What can WindMil do? What can LightTable do? What can WindMil + LightTable do? Case Study Light Table •  A stand-­‐alone product that allows engineers to look at the (me-­‐current-­‐characteris(c curves (TCC) for protec(ve devices w.r.t. each other, along with faults and device damage curves. Light Table Overview This is the “new look” for Light Table. •  One-­‐line •  TCC curves •  Curve Controls •  Dialog box Light Table Overview This is where you set-­‐up your Light Table devices: •  Device Seqngs •  Curve Characteris(cs •  Appearance in LT Outline • 
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Define topic What can WindMil do? What can LightTable do? What can WindMil + LightTable do? Case Study WindMil + Light Table •  Ability to move data between Fault Calcula(on Analysis in WindMil and TCC data in Light Table. •  Tie LightTable device data directly to devices as shown in WindMil. WindMil + LightTable This is the dialog box for moving WindMil data into LightTable. Outline • 
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Define topic What can WindMil do? What can LightTable do? What can WindMil + LightTable do? Case Study Case Study -­‐ Considera(ons •  New technology / equipment •  Crew accessibility / (me to troubleshoot •  What types of faults does your system experience? Case Study •  Verify new substa(on feeder relay seqng with exis(ng fusing scheme •  Verify fuse selec(on for new UG tap Case Study Tasks • 
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Model the new feeder relay configura(on. Determine new fault currents Add new fuse for UG Modify exis(ng protec(ve devices? Test coordina(on to see if it works Other Helpful Tasks •  Run a LUA script that will save the exis(ng device equipment off to the user tag field. One can then create a custom report that shows exis(ng equipment and proposed equipment. •  Create a custom toolbar for the fuse links. •  Create a color by custom mode to delineate OH from UG. •  Create a user-­‐defined databox that shows available fault currents and the upstream or “protected” device. •  Record all changes into a project. New Feeder Relay For fast & slow, phase and ground curves Don’t forget to set up the general seqngs on the 1st tab – fault ra(ngs and reclose intervals Case Study -­‐ Overview LUA script run before any changes are made. Project to record changes. UG colored ORANGE, OH is BLACK. Toolbar allows user to easily change devices. Max and min faults are visible, along w/ the upstream or “protected” device. Coordina(on Analysis Report indicates some errors seqng up recloser & hi-­‐
side protec(on curves. Fuse – fuse coordina(on looks fine! LightTable Coordina(on Data exported from WindMil a]er running Fault Current Analysis. Summary •  Individually, WindMil and LightTable offer several features and analysis tools to aide protec(on engineers w/ coordina(on of overcurrent protec(ve devices on a power system. •  The combina(on of the two products can provide even more features that make the task easier and faster. References •  Cooper’s “Blue Book” is the source of several of the Milso] default seqngs. •  All sorts of texts out there. •  For an interes(ng read on 40Ω Rule: hvp://tdworld.com/substa(ons/im-­‐expec(ng-­‐resistance Ques(ons??? Jim Cross, PE Homer Electric Associa(on, Inc. (907) 283-­‐2366 jcross@homerelectric.com