1. 1 Distribution Networks For Large Cities: EPRI Research on Modelling and Analysis Roger DUGAN Sr. Technical Executive Electric Power Research Inst. US

2. Frankfurt (Germany), 6-9 June 2011 2 Areas of Research in Network Analysis  Power flow studies Annual simulations of large networks  State estimation Identifying open secondary cables AMI penetration required for accurate  Power delivery efficiency

3. Frankfurt (Germany), 6-9 June 2011 3 Typical Network Topology

4. Frankfurt (Germany), 6-9 June 2011 4 Example Substation Source Model with Controllers Regulators CT prim2300 PT120 Vreg111 (13.32 kV) Vband3 R2 X3 Delay [s]60 Capacitor Controls ModeQ On:13MVAR Off:-12MVAR Delay 15s Delay 210s Delay 315s Delay 420s

5. Frankfurt (Germany), 6-9 June 2011 5 Network A Solution in OpenDSS  2,118 Buses  1,046 Primary Cables  1,552 Secondary Cables  235 Transformers  311 Secondary Load Points  2 Controlled Cap Banks  7 Tap Changer Controls Max pu. voltage = 1.0288 Min pu. voltage = 0.97399 Total Active Power: 150.547 MW Total Reactive Power: 90.1549 Mvar Active Losses: 3.60457 MW, (2.394 %) Reactive Losses: 39.0243 Mvar current-weighted point-to-point plot using bus XY coordinates only

6. Frankfurt (Germany), 6-9 June 2011 6 Network B Solution in OpenDSS  10,132 Buses  17,818 Line Segments  552 Transformers  2,272 Load Points + 10 other  4 Controlled Cap Banks  8 Tap Changer Controls Max pu. voltage = 1.0617 Min pu. voltage = 0.94585 Total Active Power: 290.822 MW Total Reactive Power: 142.377 Mvar Total Active Losses: 12.7533 MW, (4.39 %) Total Reactive Losses: 56.323 Mvar current-weighted point-to-point plot using bus XY coordinates only

7. Frankfurt (Germany), 6-9 June 2011 7 Network Protector Modelling Found Only on Secondary Networks Incorporates interrupter, communications, PTs, and CTs Open Control – Reverse Power Flow Close Control – Differential Voltage and Phasing

8. Frankfurt (Germany), 6-9 June 2011 8 State Estimation Example Can we identify secondary cable outages with AMI? –Interval demand measurements of real-time loads –Need voltage measurement to 1 decimal –Hard to distinguish parallel cables, or within a set SNL BC_5005 USN 1467 (6 in ║) USN 1468 (8 in ║) S=635.56 + j393.88 kVA Cables InLoad Voltage Both119.42 1467 only117.19 1468 only116.13 For the same load, a high residual in the estimated voltage may show: Some of the feeding cables are out Not enough change if just 1 of 14 out Can’t distinguish which of the 14 are out

9. Frankfurt (Germany), 6-9 June 2011 9 Annual Losses vs. Vreg, CVR 0.6/2.1 Loads

10. Frankfurt (Germany), 6-9 June 2011 10 Summary  Work is continuing on research into analysis and modelling of large, multi- phase urban networks State estimation/fault location Efficiency  One of the models we are studying will be converted to an IEEE Test Feeder in 2011