Geomagnetic Disturbance Power System Study in Maine Maine IEEE Joint Chapter PES/IAS Technical Meeting 7/22/2015 Presenter: Justin Michlig, PE
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Overview NERC/FERC updates State of Maine Legislative updates Geomagnetic Disturbance (GMD) Theory GMD Power Flow data requirements Results of CMP GMD analysis Future Steps
NERC Standard TPL-007-1 Applicability: Planning Coordinator Transmission Planner Transmission Owner Generator Owner Scope of facilities: Facilities operated or connected at 200+ kv Specifically transformers with a 200+ kv grounded winding are included
NERC Standard TPL-007-1 High Level Summary: R1: Maintain Models for analysis R2: Run GMD Assessments every 5 years on peak and Off-Peak models Including reactive power device and other transmission facility contingences R3: If performance not acceptable, create Corrective Action Plan(s) R4: Must have criteria for acceptable steady state voltage R5: Coordinate responsibilities between PC and TP R6: Distribute assessment to neighbors R7: TO&GO to assess thermal impact to transformers R8: TO&GO to provide thermal assessment to PC and TP
NERC/FERC Updates FERC/NERC GMD Rulemaking activity: FERC Order 779: May 16, 2013 Directs NERC to develop GMD standards for Operations and Planning FERC Process started with Oct. 18, 2012 Notice of Proposed Rulemaking (NOPR) NERC GMD Taskforce scope started in 2010 FERC Order 797: June 19, 2014 Approves EOP-010-1 Enforceable Date April 1, 2015 May 14, 2015 NOPR to approve TPL-007-1 In addition send it back to NERC for edits Increase field strength to be tested Shorten implementation time if possible Enforceable date: TBD
Maine GMD Progress MPUC Docket: 2013-00415 Started with LD 131 via resolve Report delivered to PUC & passed onto Legislature Jan 20, 2014 This report gathered pertinent documentation on past GMD and EMP events highlighting potential mitigation technologies. No tools available to quantify system impacts Continued in 2014 after PUC request to acquire software and perform analysis Results delivered to PUC end of 2014 and passed to Legislature 2014 Maine GMD/EMP Impacts Assessment LD 1363 Efforts to require installation of mitigation technologies and liability transferred to utilities Did not pass
GMD Planning Study Model the Transmission system Calculate the Geomagnetic Storm s Geoelectric intensity to be modeled Run a Geomagnetic Induced Current (GIC) DC power flow calculation Incorporate the DC results into an AC power flow simulation Apply contingencies and review for system deficiencies
DC GIC Theory - Voltages induced on the power system are calculated by geographic location and field intensity. - DC Resistance form lines, transformers, shunts, and other devices are utilized to construct the impedance network Figure 1 from K. Patil, Modeling and Evaluation of Geomagnetic Storms in the Electric Power System, DIGRE 2014. Used with Permission.
DC GIC Theory - GMD event casts a Geoelectric Field over the power system creating a DC current flow in the AC transmission system - Greatest impact while the Geoelectric Field is parallel to transmission line N Sub 1 Sub 2 DC Induced Voltage 1 0.8 0.6 0.4 0.2 0-40 -0.2 60 160 260 360-0.4-0.6-0.8-1 270 DC Induced Voltage 1 0.75 0.5 0.25 0 0 180 90
GIC Specific Data Data required in addition to traditional Steady State model: Geolocation (ex. 44.3125690,-69.8173740) Ground Grid Impedance Transformer * DC Resistance K Factor [4] Winding Connections Transformer core type NERC Benchmark Geoelectric Field intensity calculation* Other devices with low DC resistance Path *Additional detail on following slide
Transformer DC Data Auto Transformer Data Sheet Examples High Side Winding tested to ground in mω. Chose a phase or average value in Ω. Model value =.276 Ω. 1.031 Old Test reports are not easy to read and may be reported in total resistance. Divide total impedance by 3. Model value =.344 Ω
Transformer K Factor The K Factor Relates Effective GIC through the transformer to var consumption/additional losses K-Factor @ 500 kv K-Factor @ 345 kv Three Phase Shell form 0.33 0.228 Single Phase (Separate Cores) 1.18 0.814 Three Phase Three Legs 0.29 0.2 Three Phase Five Legs 0.66 0.455 Example 345 kv Grounded Auto Mvar Loss Calculation K factor Effective GIC Mvar.2 100 A 20 Three Phase Seven Legs 0.66 0.455
NERC Reference GMD peak = 8 (V/km) peak = FERC NOPR directs NERC to update value Benchmark geoelectric field magnitude at System location Factor adjustment for geomagnetic latitude Factor adjustment for regional earth conductivity model
Lookup β Condensed Geoelectric Field Scaling Factors USGS Earth Model (β) AK1A 0.56 AK1B 0.56 AP2 0.82 FL1 0.74 NE1 0.81 PT1 1.17 SL1 0.53 BOU 0.28 FBK 0.56 PRU 0.21 Physiographic Regions of the Continental United States Figure 6 from NERC GIC Application Guide 2013
Calculation of α.001 e 0.115 L L Geomagnetic North Latitude 47 28 N 56.95 N.6979 Geophysical Geomagnetic α 42 58 N 52.46 N.4169
Example Benchmark Field Calculation peak = 8 (V/km) FERC NOPR directs NERC to update value.001 e 0.115 L L Geomagnetic North Latitude 0.81 2015 Geomagnetic conversion Latitude α Benchmark Field in Maine Northern ME 56.95N.6979 4.53 V/km Southern ME 52.46N.4169 2.7 V/km What does this calculation give me again? Electric Field to use in GIC power flow calculation Conservative value used in Maine 2014 study
Maine GMD Study Specifics Scope: Includes a GIC model within the Maine transmission system (a few buses into NB and NH) Focuses on 200+ kv Analyze Geoelectric fields from 4.53 V/km to 29 V/km in Maine Discuss system improvements and cost: Possible replacement of electromechanical relays Possible upgrades to capacitor banks to improve 5 min recovery time
2014 CMP GMD Analysis Review the transmission system per NERC GMD Planning Guide Establish the worst orientation of the Geoelectric Field Report the Effective GIC flows in transformers Report system impact to voltages
GMD Field Orientation 0.996 PU Voltage vs. Geoelectric Field Orientation Shunt Switching_Chester Offline w/ Step-up out 0.994 0.992 PU Voltage 0.99 0.988 0.986 Entire Study Area State of Maine 0.984 0.982 0 50 100 150 200 250 300 350 Degrees
GMD Field Orientation PU Voltage vs. Geoelectric Field Orientation Shunt Switching_Chester Offline w/ Step-up out 321 325329 337341345349353357 1 0.996 333 0.994 0.992 0.99 309 313317 305 0.988 301 0.986 297 293 0.984 289 0.982 285 281 0.98 277 0.978 273 0.976 269 265 261 257 253 249 245 241 237 233 229 225 221 217 213 209 205 201197 193189185 181 5 9 13 17 21 25 29 3337 41 4549 53 57 61 65 69 73 77 81 85 89 93 97 101 105 109 113 117 121 125 129 133 137 141 145 149 153 157 161 165 177173169 Entire Study Area State of maine
Results from GMD field orientation effects match the orientation of the transmission in Maine. 23
CMP Results Mvar 90 80 70 60 50 40 30 20 10 Transformer Mvar Consumption vs. Geoelectric Field Strength @ 88 Chester SVC 18/345 kv Yarmouth GSU 22/345 kv #4 Keene Road GSU 115/345 kv Orrington 345/115 kv #1 Orrington 345/115 kv #2 South Gorham 345/115 kv #1 South Gorham 345/115 kv #2 Mason 345/115 kv #1 Macguire Road 345/115 #1 Keene Road 345/115 kv #1 Coopers Mill 345/115 kv #3 Surowiec 345/115 kv #1 0 0 5 10 15 20 25 30 35 V/km Geoelectric Field Albion Road 345/115 #1 Larrabe Rd 345/115 #1
CMP Results 1.04 Maine 345 kv Transmission Voltage vs Geoelectic Field Strength @ 88 1.035 V PU 1.03 1.025 1.02 1.015 1.01 1.005 CHESTER SVC ORRINGTON COOPERS MILL RAVEN FARM MAINE YANKEE SUROWIEC YARMOUTH SOUTH GORHAM BUXTON MASON ALBION ROAD LARRABEE RD MAGUIRE ROAD KEENE ROAD 1 0 5 10 15 20 25 30 35 V/km Geoelectric Field
CMP Results Reactive Reserves vs. Geoelectric Field 1800 1600 1400 1200 1000 Mvar 800 Online Capacitive Reactive Devices 600 400 Total Installed Capacitive Reactive Devices 200 0 0 5 10 15 20 25 30 35 V/km *Excludes Generator Reactive Capability, which is a significant source of reactive power
GMD Field Orientation Effective GIC A/phase for Maine transformers Degree Amp Max 4.53 V/km 14 V/km 20 V/km 23.5 V/km 29 V/km NERC 1 in 100 year Benchmark Study team assumed 1 in 50 year event Study team assumed 1 in 100 year event Study team assumed 1 in 200 year event Study team assumed 1 in 500 year event 2 winding delta - wye Chester SVC 18/345 kv 162 76 235 336 395 487 Yarmouth GSU 22/345 kv #4 144 49 152 217 255 315 2 winding Auto Xfmrs Keene Road GSU 115/345 kv 160 32 98 140 165 204 Orrington 345/115 kv #1 64 4 14 20 23 29 Orrington 345/115 kv #2 64 4 12 17 20 25 South Gorham 345/115 kv #1[1] 60 1 3 5 6 7 South Gorham 345/115 kv #2 60 12 36 51 60 74 Mason 345/115 kv #1 111 6 20 28 33 41 Macguire Road 345/115 #1 30 27 83 120 139 172 Keene Road 345/115 kv #1 160 6 18 26 31 38 Coopers Mill 345/115 kv #3 30 35 109 155 182 225 3 winding Auto xfmrs Surowiec 345/115 kv #1 38 17 52 75 88 108 Albion Road 345/115 #1 30 60 186 266 313 386 Larrabee Rd 345/115 #1 135 48 149 213 250 308
CMP Results Transformer Effective GIC using Each transformers most Impactful Geoelectric Field Angle 600 500 Chester SVC 18/345 kv Yarmouth GSU 22/345 kv #4 Keene Road GSU 115/345 kv Orrington 345/115 kv #1 Effective GIC A/Phase 400 300 200 Orrington 345/115 kv #2 South Gorham 345/115 kv #1 South Gorham 345/115 kv #2 Mason 345/115 kv #1 Macguire Road 345/115 #1 Keene Road 345/115 kv #1 Coopers Mill 345/115 kv #3 100 Surowiec 345/115 kv #1 0 0 5 10 15 20 25 30 35 Geoelectric Field Magnitude V/km Albion Road 345/115 #1 Larrabe Rd 345/115 #1
CMP Assumptions Change Results PU Voltage vs. Geoelectric Field Orientation @ 15V/km 353357 1.01 337 341345349 325 329333 1.005 313 317321 309 1 305 301 0.995 297 293 289 0.99 285 281 0.985 277 273 0.98 269 265 261 257 253 249 245 241 237 233 229 225 221 217 213 209 205 201 197 193 189185 1 181 5 9 13 17 21 25 29 33 37 41 4549 53 57 61 65 69 73 77 81 85 89 93 97 101 105 109 113 117 121 125 129 133 137 141 145 149 153 157 161 177173169 165 Entire Study Area State of maine
CMP Assumptions Change Results PU Voltage vs. Geoelectric Field Orientation @ 15V/km_No Shunt Switching_Chester Offline w/ Step-up in-service 321 325329 353357 0.995 333 337341345349 0.99 0.985 309 313317 305 0.98 301 297 0.975 293 289 0.97 285 281 0.965 277 273 0.96 269 265 261 257 253 249 245 241 237 233 229 225 221 217 213 209 205 201197 193189 185 1 181 5 9 13 17 21 25 29 3337 41 4549 53 57 61 65 69 73 77 81 85 89 93 97 101 105 109 113 117 121 125 129 133 137 141 145 149 153 157 161 165 169 173 177 Entire Study Area State of maine
Maine Analysis Results Voltage performance of the Maine transmission system was very good Worst GMD storm angle ~88 degrees Each transformer had different angles which excited them the most Only Chester above 75 A/phase GIC recommended for thermal screening a 8 V/km benchmark event At 29 V/km field tested 8 transformers above thermal screening threshold
Not Covered But Important Harmonic Analysis May cause unintended tripping, but newer relays can filter No great method found to analyze GMD Harmonic effects
Maine Analysis Prospective Monitoring Chester Neutral current since 1991 GIC has been present and the power system has had voltage changes due to it Peak GIC neutral flow of 98 A (~33A/phase) Simulations of 75 A/phase during benchmark event @ 8 V/km Capacitors, SVC Filters, and potential UPS functionality issue during events No customer outages No associated customer equipment damage reported
Maine Analysis Next Steps Reassemble previous study team Perform recommended thermal assessments of transformers Scope GMD monitoring for installation
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References [1] NERC GMD Project Page TPL-007-1 GMD Task Force Planning Guide Benchmark Geomagnetic Disturbance Event Description Thermal Screening Criterion White Paper Transformer Thermal Impact Assessment White Paper Application Guide [2] Geomagnetic Location Calculator - http://wdc.kugi.kyoto-u.ac.jp/igrf/gggm/ [3] R. Horton, D. Boteler, T.J. Overbye, R. Pirjola, and R.C. Dugan, A Test Case for the Calculation of Geomagnetically Induced Currents, IEEE Transactions on Power Delivery, Vol. 27, No. 4, October 2012, pages 2368-2373. [4] X. Dong, Y. Liu, J. G. Kappenman, Comparative Analysis of Exciting Current Harmonics and Reactive Power Consumption from GIC Saturated Transformers, Proceedings IEEE, 2001, pages 318-322. [5] K. Patil, Modeling and Evaluation of Geomagnetic Storms in the Electric Power System, C4-306, CIGRE, 2014