IEEE Power Engineering Society Toronto Chapter Ontario Wind Turbines – Testing of Electrical Safety Kinectrics Seminar May, 2007 Eugene Peter Dick IEEE Senior Member 49 Lynngrove Ave Toronto, Ontario

1.5 MW GE Wind Turbine

Foundation - Elevation

Tower Height: 65 to 80+ m Base Flange: 5 m , circa 200 bolts (ext, interior) Sections: 3 joined by interior flanges, platforms Access: ladder with fall restraint Bus type: rigid or locomotive flexible cable Section: 500+ mm 2 ( mcm) Erection: 500 tonne crane

Bolt Ring – Duplicated Inside

500 Tonne Crane

Nacelle

Rotor Blades Diameter: 71 m Speed: 12 – 22 rpm Gearbox: 3-step planetary spur gear, ratio 72 Power vs wind speed:kWk/hr cut out90

Generator Rating: 1.5 MW, 1.72 MVA, 575 V, stator A Type: double fed, 3 , (induction?) synchronous Rotor via PWM drive rated 300 kW Poles: 6, - / + 20 % speed (864 to rpm) H (inertial const): 6.55 s (gen alone 0.8 s) Xd” (subtransient reactance): 0.27 pu Protection: V over / under / unbal, f over / under Control: pf or current compensated V

Typical Interconnect Requirements < 88 % V trip in 2 s, < 50 % V trip in 0.16 s > 110 % V trip in 1 s, > 120 % V trip in 0.16 s < 59.8 Hz trip in 300 s, < 57 Hz trip in 0.16 s  V on synch: < 5 %, flicker IEEE Std 519, 1453 dc: < 0.5 % on I harmonics: < 4, 2, 1.5, 0.6 % (h<11, 17, 23, 35) islanding with load: trip in less than 2 s no impact on utility feeder protection

Stepup Transformer

Transformer / Collection System Xmer: 575 / 34.5 kV, Yg / , Z = j 5.70 % 35-kV, 67 mm 2 (AWG 2/0) concentric Neu cable several units daisy-chained to riser pole may run Neu / bond back to main substation overhead line may be 3 or 4-wire typically 4 collection lines to main station, CB each collection line may have gnding Xmer main Xmer: 34.5 / 230 kV, 100 MVA

Stepup Transformer Cabinet

Cable Run to Riser Pole

Collection Line to Main Substation

Main Substation

Grounding Transformers

230-kV System Tie

Erie Shores Setting

Erie Shores Layout

Erie Shores Ground Electrode

Sault Ste Marie (Prince) Wilderness

Prince Layout

Prince in Autumn

Prince in Late Autumn

Prince Ground Electrode

Prince 1 Collection Cable

Grounding - Objectives limit V between touchable objects provide low Z path so protection sees fault I direct fault I, lightning away from equipment minimize interference

Grounding - Definitions Remote earth: soil not rising in potential on faults Bonding: to connect two objects with low Z path Grounding: to provide bonding to remote earth G System: all conductors that facilitate grounding G Current: fault current that enters a G system G Electrode: conductors that dissipate I into soil G Potential Rise: V between G system, remote soil Step Potential: foot-to-foot V during system fault Touch Potential: hand-to-foot V on system fault

Grounding – Tested Quantities GPR: general hazard indicator, telco pairs Step V: coord to safe body withstand (180, V) Touch V: coord to safe body withstand (168, 663 V) Touch types: structure, mesh, fence, gate, exterior Current splits: on external connections: Neu, Ohg Soil resistivity: model all of above Surface stone resistivity: check for deterioration Conductor integrity:  measured and modelled

GPR = Rg Ig Ig - Vg + Telco

Measure Rg with Fall of Potential C1 P1 C2 P2 x c

Locate Probe P at 62 % of Probe C

When Soil Has Two Layers C1 P1 C2 P2 x c h 11 22

Adjust Location for P to C Ratio

Interconnections Affect P to C Ratio C1 P1 C2 P2 x c

Soil Anomalies Affect P to C Ratio low  C1 P1 C2 P2 x c high 

Proximity Correction: Arbitrary P, C low  C1 P1 C2 P2 x c high 

Running Out Leads in Fair Weather

Testing When Snow Flies

Reading the AC Milliohm Meter

Six Towers Left Before Nightfall

Network Analyzer for Current Splits low  C1 Split- Core CT c high  C2 Network Analyzer

Rogawski Coil for Current Splits

Counterpoise Current Split

Network Analyzer, Scope, Megger

Network Analyzer for Impedance low  C1 P1 P2 x c high  C2 Network Analyzer

Equiv Cct for Proximity Corrections XcgXgp Xcp Ic - Ic Rcg +  Ic +  Ic Rgp - Ic Rcp + + Vp - Zd Rg

Proximity Correction Method Zg= Zm +  Rgp +  Rcg – Rcp  = Zd / ( Zd + Rg )  =b + Rcg / ( Rcg + Zd ) measure Zm and  read Zm at several locations for P find Zg for each, average these estimates calculate standard deviation as quality check

Measuring Step Potential

Measuring Touch Potential

Summary When sandy soil or rock raise Rg, tests useful Fall of Pot bad with soil anomalies, interconnections Proximity Correction method has P and C opposite Multiple estimates of Zg averaged for less noise Standard deviation of Zg checked for quality Measuring current splits good with interconnections