Consolidated Edison s Experience with On-line Monitoring and Mitigation of Geomagnetic Disturbances

Transcription

1 Consolidated Edison s Experience with On-line Monitoring and Mitigation of Geomagnetic Disturbances Gary R. Hoffman, Advanced Power Technologies Sam Sambasivan, Consolidated Edison Vincenzo Panuccio, Consolidated Edison Mypsicon, November

2 Agenda Overview of GIC Activities at Con Edison Selecting the vulnerable transformers GIC Monitoring according to IEEE Std. C GIC Modeling of 345 kv Autotransformers Results of Analysis Conclusion 2

3 Selection of Vulnerable Transformers According to IEEE Std C Total susceptibility to effects of GIC is determined by: Transformer Design Based Susceptibility GIC Level Based Susceptibility Design Based Susceptibility Category A: Transformers not susceptible to effects of GIC Category B: Transformers least susceptible to core saturation Category C: Transformers susceptible to core saturation and structural parts overheating Category D: Transformers susceptible to both core saturation as well as possible damaging windings and / or Structural parts overheating GIC Level susceptibility divides transformers into 3 categories: Three ranges of GIC levels (High, Medium, and Low) 3

4 Selection of Vulnerable Transformers at Con Edison Which Transformers to Monitor Conducted review of 2012 EPRI Sunburst data Commissioned a CEATI study to rank transformers based on GIC susceptibility Conducted comparison of highest observed GIC levels at Con Edison and results given by GIC calculation study conducted by CEATI Selected transformers based on these results 4

5 Selection of Vulnerable Transformers at Con Edison GIC Susceptible Transformers Location Core Design CEATI Relative Ranking(GIC) Transformer 1 Shell Form 1 Transformer 2 Shell Form 2 Transformer 3 Shell Form 2 Transformer 4 Shell Form 3 Transformer 5 Shell Form 3 Transformer 6 Shell Form 4 Transformer 7 Shell Form 4 Transformer 8 Shell Form 5 Transformer 9 Shell Form 6 Transformer 10 Shell Form 5 Transformer 11 Shell Form 5 Transformer 12 Shell Form Not modeled in CEATI study 5

6 GIC Monitoring Why Monitor? Provides the ability to see real time what is happening when GIC events occur Continuous monitoring and operation response procedure is an effective and less costly alternative to both passive and active blocking schemes. Provides the gathering of data for post event analysis to help us better understanding system strengths and weaknesses during a GMD event 6

7 GIC Monitoring Monitoring According to IEEE Std. C Measure GIC of neutral current Measure harmonics on bushing CTs Deploy GIC or part-cycle core saturation detection Place fiber optic temperature sensors at strategic locations on new and re-built transformers Perform DGA of transformers when there is evidence of part-cycle core saturation at elevated levels of GIC 7

8 GIC Monitoring GIC & Harmonics According to IEEE Std. C GIC is quasi-dc that requires ultra low frequency measurement of GIC from X0, H0, Y0, or X0H0 bushing Hall effect current sensors desensitized at power system frequency is recommended Monitor current harmonics in three-phase transformers on the outer pahases The magnitude of even current harmonics due to partcycle core saturation dominate odd current harmonics 1 1 US Patent 9,018,962 and Foreign Patents Pending 8

9 GIC Monitoring Typical GIC Waveform GIC, AmpsADC IEEE Std C Reprinted with permission from IEEE. Copyright IEEE All rights reserved. Any comments or interpretations of the Material are the Author s and do not represent the views of IEEE, its members or affiliates.

10 GIC Monitoring Typical GIC Waveform 10 IEEE Std C Reprinted with permission from IEEE. Copyright IEEE All rights reserved. Any comments or interpretations of the Material are the Author s and do not represent the views of IEEE, its members or affiliates.

11 GIC Monitoring Current Harmonic Order of Part-Cycle Core Saturation 11 IEEE Std C Reprinted with permission from IEEE. Copyright IEEE All rights reserved. Any comments or interpretations of the Material are the Author s and do not represent the views of IEEE, its members or affiliates.

12 GIC Monitoring Part-Cycle Core Saturation Detection on Three-phase Auto 12

13 GIC Monitoring How we Monitor? Comprehensive GIC monitoring device installed at all vulnerable transformers Device monitors: Temperature Load Current Harmonics DC Neutral Current GIC Monitor Device collects data and generates alarms that operations uses to determine system status and take action during GIC events 13

14 GIC Monitoring Operation Response Procedure Level 1 Alarm- Measured neutral GIC current exceeds a threshold after a preset time delay Operator action -Notify Substation operator, monitor GIC currents and temperatures at all monitored transformer locations Report findings to Engineering. EMS Level 2 Alarm (OOE Category 2) Level 1 Alarm plus high level of harmonics- this indicates core saturation Operator action - De-load the transformer, monitor temperatures Report findings to Engineering. Level 3 Alarm (OOE Category 1) - Level 2 Alarm plus transformer temperature exceeding temperature guideline Operator action Remove the transformer from service Report findings to Engineering. Monitored Metrics Neutral Current and Temperature are analog values. Harmonics point is a digital point. If total harmonic distortion goes above threshold, the point will switch from Normal to Alarm Up. Alarms Alarms are digital points. If thresholds are exceeded the point will switch from Normal to Alarm Up. 14

15 GEO-MAGNETIC DISTURBANCE DISPLAY LOCATION NEUTRAL CURRENT TEMPERATURE HARMONICS ALARMS Minor Major Critical Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL Transformer 8 20 A DEG C NORMAL ALARM UP NORMAL NORMAL Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL Transformer A 2.01 DEG C NORMAL NORMAL NORMAL NORMAL

16 GIC Modeling High voltage transmission system Substation Model: Longitude & latitude & ground grid resistance Transmission line DC resistance GIC Flows, Power Flow, Thermal Analysis of Transformers Transformer, shunt reactor and phase angle regulator winding DC resistances 16

17 GIC Modeling Software Validation GIC analysis & load flow software IEEE Benchmark test case (GIC Flow) DC Model of High Voltage Transmission System (GIC Network Model) Model Validation Rotate E-Field from 0 o to 180 o Compare simulated neutral currents to measurements 17

18 GIC Modeling Study Database NYISO planning model, load flow base case modified for Con Edison peak load Geographic Long.=74W, Geographic Lat.=41N (Mag. Lat=48) corresponds to Piedmont (PT-1) region from US Geological Survey (USGS) Conductivity High for PT-1 Region Geo-electric fields (E-field) since 1985 less than 2V/km (USGS) Max E-field by year for various regions (mv/km) PT-1 max E-field estimated by year 18

19 GIC Modeling Transmission Perf. During GMD Draft TPL standard: Epeak =8 α β (V/km) Epeak = V/km= 2.28 V/km 8 V/km is a reference peak geoelectric field amplitude derived from statistical analysis of historical magnetometer data α scaling factors to account for local geomagnetic latitude β scaling factors to account for local earth conductivity 19

20 Results of Analysis GIC Flows Analysis Simulation done at 1 V/m electric field Transformer Neutral GIC Flows in Ampere for Different Electric Field Orientation 0 o 15 o 30 o 45 o 60 o 75 o TR TR TR TR TR TR TR TR *No peak losses observed between 90 o and 135 o, thus was not reported in table 20

21 Results of Analysis Measured GICs For Some 345 kv Transformers Example neutral current readings for July 14, 2013 disturbance K5 reported by NOAA 21

22 Results of Analysis Measured GICs For Some 345 kv Transformers Neutral current readings Transformer Transformers neutral current readings July 14, :50PM Approx. K5 July 14, :03AM Approx. K5 TR TR TR TR TR TR TR TR TR TR TR TR TR TR

23 Results of Analysis Simulated vs. Measured GICs For Some 345 kv Transformers Stronger correlation for E-field pointing Eastward (around 90 o ) 23

24 Results of Analysis US Geological Survey (USGS) E-field estimations USGS E-field estimations show no prevalent direction Ey (North) in mv/km Ex (East) in mv/km E-Field Direction at Each Minute from July 14, 2013 Event 24

25 Results of Analysis Simulated vs. Measured GICs For Some 345 kv Transformers USGS E-field estimations show no prevalent direction (provided direction may be VERY off, but consistently off according to USGS) 18 E-Field Orientations Ey (North) in mv/km July 14, 2013 at 9:03PM July 14, 2013 at 8:50PM Ex (East) in mv/km 25

26 Conclusion Completed transformer vulnerability assessments Completed GIC capability evaluations Completed installation of GIC part-cycle core saturation detection monitors at 14 locations Implemented system operation response to GIC Completed GIC network model and flows for the 345 kv transmission system including autotransformers, PARs and shunt reactors Further work needs to be done with gathering more detailed event data and correlating it to model results. 26

27 Thank you!