GIC Calculations Using PSS E. Live Demonstration February 16, 2017

Transcription

1 GIC Calculations Using PSS E Live Demonstration February 16, 2017 usa.siemens.com/digitalgrid

2 NERC TPL GMD Vulnerability Assessment Process Source: NERC GMD Task Force Documents Page 2

3 How to run GIC analysis in PSS E? Page 3

4 PSS E GIC analysis GUI Page 4

5 Development of DC system model Power flow network data reduced to just resistance network with these modifications: Transmission lines modeled as resistor in series with induced voltage Line reactors / charging ignored Grounded two- and three-winding transformers modeled with their winding resistance to ground Grounded auto-transformers are modeled with their common and series winding resistance Grounded Bus shunts are modeled Equivalent station grounding resistance is modeled Transformer GIC blocking devices are modeled Page 5

6 GIC flow in various transformer configurations The effective GIC (I eff ) flow in a transformer due to GICs flowing in one or more of its winding is dependent upon transformer type. Refer PSS E Program Application Guide, Volume 1 Page 6

7 Effective GIC Two-winding transformer Page 7

8 Effective GIC Two-winding auto transformer Page 8

9 Mvar/Ampere Scaling Factor (K factor ) One of the effects of the GICs flowing in transformer windings is that the transformer is subjected to half-cycle saturation resulting in increased reactive power (Mvar) losses in these equipment. Using GIC to Mvar scaling factors transformer reactive power losses are calculated. When a specific K factor value is provided for a transformer: Q = I eff K factor Using generic scaling factor value based on the transformer type: VH Q = Ieff K factor 500 where V H is Transformer Windings highest voltage in kv. Page 9

10 Generic Scaling Factors (a) K factor determined based on transformer cores Core Design Cores K factor Three-phase, shell form Single-phase (three separate cores) Three-phase, 3-legged, core form Three-phase, 5-legged, core form Three-phase, 7-legged, core form (b) K factor determined based on base kv of transformer windings Windings Highest Voltage K factor Unknown core, <= 200 kv 0.6 Unknown core, > 200 kv and <= 400 kv 0.6 Unknown core, > 400 kv 1.1 Source: 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 Page 10

11 GMD events modeled in PSS E Uniform Geoelectric Field E(t) Ignores effects of local earth conductivity and local geomagnetic latitude Benchmark GMD Event E(t) E = 8 V/km Considers α, the scaling factor to account for local geomagnetic latitude, and β, the scaling factor to account for the local earth conductivity structure Non-uniform Geoelectric Field E(t) Considers 1-D local earth conductivity models Calculates E(t) using Complex Image Method Page 11

12 GIC Data File usa.siemens.com/digitalgrid

13 GIC Data File The data required to run GIC analysis which does not exist in PSS E power flow case is provided using this file. The accuracy of GIC calculations will depend on the data provided in this file. GIC data file Text file Default extension:.gic Page 13

14 GIC Data File Identification and substation data Page 14

15 GIC Data File Transformer data Page 15

16 GIC Data File Fixed shunt and branch data Page 16

17 GIC Data File User Earth model data Page 17

18 GIC Data File Branch Data Notes GMD induced electric field can be specified in branch data record in terms of INDVP and INDVQ. PSS E determines branch GMD induced efield as below. 1. When INDVP and INDVQ are specified in GIC data file, the total branch GMD induced electric field is then determined as: Page 18 Induced Efield = INDVP + j INDVQ volts 2. When INDVP and INDVQ are not specified (blank) in GIC data file, branch induced efields are calculated as per selected GMD event and branch geographical location. 3. When INDVP=0 and INDVQ=0 are specified in GIC data file, the branch is treated as underground cable. It is part of dc network, GICs can flow in this branch, but does not have induced efields. For uniform and benchmark GMD events, Induced efield is real value, but for non-uniform field modeling this will be complex value. Induced electric field will have positive polarity at branch To Bus (J bus).

19 GIC Data File User Earth model notes TPL defined Earth Conductivity Models for US and Canada are modeled as standard earth models (just use its name in GIC data file). If any other Earth Model is required, use this data record to define such an earth model. A total of up to 50 user earth models are allowed. Each earth model may have up to 25 layers. Use as many records needed to specify the data. The thickness of the last layer is infinity. This is specified as any value less than 0.0 (= for example). The thickness value less than 0.0 is also used as end of earth model data. Page 19

20 GIC Data File Example Create from Python Script (A) Generate GIC data Microsoft Excel template import psse34 import psspy, gicdata psspy.psseinit() savfile="nerc_gic_app_guide_exam_v33.sav" excelfile="template_2.xlsx" excelfile=gicdata.template_excel(savfile,excelfile, showexcel=true) (B) Edit template as required (C) Create GIC data file from template import psse34 import gicdata excelfile="template_2.xlsx" gicfile="template_2.gic" gicdata.excel2gicfile(excelfile, gicfile) Page 20

21 GIC Analysis usa.siemens.com/digitalgrid

22 PSS E GIC Calculations GMD Storm Scenario PSS E GIC Module PSS E GIC Data PSS E Power Flow Network GICs, Transformer Q Losses PSS E Power Flow Network with GIC Losses AC Power flow studies Contingency analysis PV/QV analysis Dynamic analysis Page 22

23 Run GIC Analysis from PSS E GUI Page 23

24 Run GIC Analysis from Python Script (A) Run GIC activity (gic_3) using psspy module This runs GIC activity and produces GIC analysis results in PSS E Text reports. (B) Run GIC analysis and retrieve results in Python objects using arrbox.gic OR pssarrays modules This runs GIC activity and returns GIC analysis results in Python objects. Page 24

25 arrbox.gic.gic OR pssarrays.gic objects This provides pythonic interface to GIC activity and also retrieves results into Python objects. import arrbox.gic gicobj = arrbox.gic.gic(savfile, gicfile, efield_mag, efield_deg, tielevels=0, study_year=0, thermal_ana_optn=0, substation_r=0.1, branch_xbyr=30.0, transformer_xbyr=30.0, efield_mag_local=0.0, efield_deg_local=0.0, efield_type='uniform', efield_unit='v/km', addfile_optn='rdch', gic2mvar_optn='kfactors', earth_model_name='', scan_storm_event='', power_flow_optn='', ejet_million_amps=0.0, ejet_halfwidth_km=0.0, ejet_period_min=0.0, ejet_height_km=0.0, ejet_center_deg=0.0, addfile='', purgfile='', rnwkfile='', pygicfile='nooutput', basekv=[], areas=[], buses=[], owners=[], zones=[], basekv_local=[], areas_local=[], buses_local=[], owners_local=[], zones_local=[], pf_itmxn=_i, pf_toln=_f, pf_tap=_i, pf_area=_i, pf_phshft=_i, pf_dctap=_i, pf_swsh=_i, pf_flat=_i, pf_varlmt=_i, pf_nondiv=_i) OR import pssarrays gicobj = pssarrays.gic(savfile,...) Page 25

26 Example IEEE GIC Test Case Network R. Horton, et.al., A Test Case for the Calculation of Geomagnetically Induced Currents, IEEE Transactions on Power Delivery, Vol. 27, No. 4, October 2012, pages Page 26

27 IEEE GIC Test Case Calculations with Activity GIC Refer files in folder..\pti\pssexx\example ieee_gic_test_case.sav ieee_gic_test_case.gic ieee_gic_test_case.sld Page 27

28 GIC Calculations Report Page 28

29 GIC Calculations Report (continued) Page 29

30 GIC Calculations Report (continued) Page 30

31 GIC Calculations Report (continued) Page 31

32 GIC Calculations Report (continued) Page 32

33 GIC Results on Network Maps Python Module arrbox.gicmaps.gicmaps OR pssarrays.gicmaps Use arrbox.gicmaps python module to display GIC calculation results on network map. pygicfile file produced by activity GIC or arrbox.gic.gic used as input to GICMAPS. Need open source python modules: numpy, matplotlib, basemap Get details as >>> import arrbox.gicmaps >>> help(arrbox.gicmaps) Page 33

34 GIC Results on Network Maps (continued) Page 34

35 GIC Results on Network Maps (continued) Page 35

36 GIC Results on Network Maps (continued) Page 36

37 GIC Results on Slider Diagrams Open sample.sav and sample.sld files in PSSExx. Run GIC analysis using: sample.gic GMD event as: Benchmark, scan degrees Show GIC results on slider diagram: Select slider tab Menu Diagram >Results to show >GIC results Press Title Tool Button to show title on slider diagram Page 37

38 GIC Results on Slider Diagrams (continued) Page 38

39 scan_d_m option scan results Page 39

40 Conclusion usa.siemens.com/digitalgrid

41 TPL Requirements and PSS E Conclusion Page 41 TPL Requirements R1 Identify individual or entity Company policy R2 R3 Maintain System models and GIC System (DC) models Have acceptable voltage criteria during the benchmark GMD event How to meet? PSS E Case and GIC data files Company policy R4 GMD Vulnerability Assessment studies PSS E GIC Module and other PSS E activities R5 1) Provide GIC flow information for worst case geoelectric field orientation 2) Effective GIC time series, GIC(t) R6 Conduct a thermal impact assessment with I eff /phase > 75 Amps 1) PSS E GIC module output 2) Implemented, will be available in next PSS E release Need transformer thermal response capability data R7 Develop corrective action plan a) company policy: based on grid knowledge develop this b) implement in PSS E Case and GIC data files

42 PSS E GIC Module Conclusion Fully integrated in PSS E Uses standard PSS E networks (.sav or.raw files) No Sequence data required Additional data required for GIC calculations supplied through external GIC data file GIC data files can be prepared using interactive tools, GIC Python module and Microsoft Excel or a text editor Activity GIC creates comprehensive and customizable text report Python scripts can be used to run GIC calculations, create custom reports and show GIC results on Network maps GIC calculations automatically run orientation scans to find worst orientation and magnitude scans to find maximum possible storm strength that system can withstand Page 42

43 Contact Krishnat Patil Senior Staff Software Engineer Siemens PTI Phone: Jyothirmai Chittyreddy Staff Consultant Siemens PTI Phone: usa.siemens.com/digitalgrid Page 43