Bus 2DFW

Bus 4SA

Bus 5VAL

Bus 6COAL

Bus 7WIND

300 km

250 km

150 km300 km

400 km

500 km400 km

Bus 3UT

Bus 1HOU

Positive-sequence line constants for each 345kV circuit:

• R = 0.06 Ω/km per conductor

• L = 1 µH/m

• C = 12 pF/m

• Rating = 800 A per conductor

• From the L, XL (500 km) = 188.5 Ω

• For 345 kV, 100 MVA base, Zbase = 1190 Ω

• For each 500 km circuit, XL = 0.158 pu

• Thus, four parallel circuits have XL = 0.040pu, and six parallel circuits have XL = 0.026 pu

Relatively small phase angle variation in central ERCOT

McDonald Observatory

PMU

UT Austin PMU

Bus 2DFWBus 2DFW

Bus 4SA

Bus 4SA

Bus 5VAL

Bus 5VAL

Bus 6COALBus 6COAL

Bus 7WINDBus 7WIND

300 km

250 km

150 km300 km

400 km

500 km400 km

Bus 3UT

Bus 3UT

Bus 1HOUBus 1HOU

Positive-sequence line constants for each 345kV circuit:

• R = 0.06 Ω/km per conductor

• L = 1 µH/m

• C = 12 pF/m

• Rating = 800 A per conductor

• From the L, XL (500 km) = 188.5 Ω

• For 345 kV, 100 MVA base, Zbase = 1190 Ω

• For each 500 km circuit, XL = 0.158 pu

• Thus, four parallel circuits have XL = 0.040pu, and six parallel circuits have XL = 0.026 pu

Relatively small phase angle variation in central ERCOT

McDonald Observatory

PMU

UT Austin PMU

U.T. Pan AmPMU

Synchrophasor Homework Network for ERCOT

U.T. McDonald ObservatoryPMU

Oscilloscope View. If UT Austin = 0º ref, then McD leads by 60º, and Pan Am lags by 30º

360º

+60º −30º

Small oscillations in the relative phase angles give an indication grid stability. Essentially, these oscillations provide an “EKG” for large power grids.

Angle Ringdown at McD

1 Minute Window Angle Ringdown at PanAm

1 Minute Window

Frequency, 3 Minutes Beginning April 24, 2011,19:54 CDT

59.98

59.99

60.00

60.01

60.02

60.03

60.04

60.05

0 1 2 3

Minutes

Hz Harris 69

PanAm

Frequency, 3 Minutes Beginning April 24, 2011,19:54 CDT

59.98

59.99

60.00

60.01

60.02

60.03

60.04

60.05

0 1 2 3

Hz Harris 69

McD

Voltage Phase Angle, 3 Minutes Beginning April 24, 2011,19:54 CDT

-1

0

1

2

3

0 1 2 3

Deg

rees

McD

Voltage Phase Angle, 3 Minutes Beginning April 24, 2011,19:54 CDT

18

19

20

21

22

0 1 2 3

Minutes

Deg

rees

PanAm

Unit Trip,

April 24, 2011,

21:15 CDT

Unit Trip,

April 24, 2011,

21:15 CDT

PanAm

McD

Unit Trip, April 24, 2011, 21:15 CDT

Start Sec Stop Sec A t1 B Tau1 t2 C Tau2 Wdamp24.5 28.9 13.31 24.88 13.98 0.14 25.14 0.88 2.97 3.68

Fdamp Zeta0.585 0.092

Unit Trip April 24, 2011, 21:15:25 CDT. McDonald Angle Relative to U.T. Austin

13

14

15

23 24 25 26 27 28 29 30 31 32 33

Seconds

Deg

rees

Measured

Curve Fit

Damped Resonant Frequency, Hz Normalized

Damping Coefficient

Ring Magnitude, degrees

Steady-State Change = 13.98 – 13.31 = 0.7 degrees

McDonald

Start Sec Stop Sec A t1 B Tau1 t2 C Tau2 Wdamp24.5 28.9 17.68 24.62 14.40 0.23 24.93 -2.23 1.58 3.71

Fdamp Zeta0.591 0.170

Unit Trip April 24, 2011, 21:15:25 CDT. Pan Am Angle Relative to U.T. Austin

12

13

14

15

16

17

18

23 24 25 26 27 28 29 30 31 32 33

Seconds

Deg

rees

Measured

Curve Fit

Damped Resonant Frequency, Hz Normalized

Damping Coefficient

Ring Magnitude, degrees

Steady-State Change = 14.40 – 17.68 = -3.3 degrees

Pan Am

Damped Oscillation Frequencies, Magnitudes, and Normalized Damping Ratios for the Hour 21:00 – 22:00 CDT, April 24, 2011

McD Voltage Angle Relative to UT Austin UT Pan Am Voltage Angle Relative to UT Austin

Voltage Phase Angle Relative to UT Austin1-Minute Averages, Tuesday, April 26, 2011, Beginning 09:00 CDT

-50

-40

-30

-20

-10

0

10

20

30

40

50

57 58 59 60 61 62 63 64 65 66 67

Hour of the Week, CDT

De

gre

es

McD

PanAm

West Texas Voltage Phase Angle Advances 80+ Degrees in 6 Hours

UT Pan Am Voltage Phase Angle wrt Central ERCOT

-20

-15

-10

-5

0 1 2 3 4 5

Minute Beginning 07:26 CDT on April 27, 2011

UT Pan Am Voltage Phase Angle wrt Central ERCOT

-15

-10

-5

68 69 70 71 72 73 74 75

Second Beginning 07:26:00 CDT on April 27, 2011

UT Pan Am Voltage Phase Angle wrt Central ERCOT

-20

-15

-10

106 107 108 109 110 111 112 113

Second Beginning 07:26:00 CDT on April 27, 2011

UT Pan Am Voltage Phase Angle wrt Central ERCOT

-20

-15

-10

226 227 228 229 230 231 232 233

Second Beginning 07:26:00 CDT on April 27, 2011

Frequency at Harris 69kV Substation (by UT Austin Campus)

59.80

59.85

59.90

59.95

60.00

60.05

60.10

0 1 2 3 4 5

Minute Beginning 04:51 CDT on April 27, 2011

Frequency at Harris 69kV Substation (by UT Austin Campus)

59.80

59.85

59.90

59.95

60.00

60.05

0 1

Minute Beginning 04:51 CDT on April 27, 2011