PMU Error Impact on Measurement-Based Applications

Yilu Liu, ORNL/UTK

Jose Gracia, ORNL

Paul Ewing, ORNL

Jiecheng Zhao, UTK

Jin Tan, UTK

Ling Wu, UTK

Lingwei Zhan, UTK

DOE/OE Transmission Reliability Program

June 10, 2015, Washington, DC

Presenter: Yilu Liu

liu@utk.edu

Project Team

2

Objective and Accomplishments

• Overall Project Objective Assess the impact of the measurement errors on synchrophasor based applications

• Looking Back (July 2014 - June 2015) – Completed error impact study for four (4) applications

– Three (3) Related Best Papers at 2015 PES General Meeting

J. Zhao, L. Zhan, Y. Liu, H. Qi, J. R. Garcia, and P. D. Ewing, “Measurement

accuracy limitation analysis on synchrophasors”, IEEE PESGM 2015. (This

study performed in 2014)

L. Zhan, J. Zhao, S. Gao, J. Culliss, Y. Liu, and Y. Liu, “Universal grid

analyzer design and development”, IEEE PESGM 2015 (related work).

H. Lu, L. Zhan, Y. Liu, and W. Gao, “A GPS-free power grid monitoring

system over mobile platforms”, IEEE PESGM 2015 (related work).

3

FY15 Accomplishments and Deliverables

• Effect of renewable sources on measurement accuracy

– Study impact of wind turbine blade shadow effect (Mar 2015)

– Study impact of harmonics from PV inventers (July 2015)

• GPS loss statistics and impacts

– GPS loss rate from historical PMU and FDR data (Aug 2015)

– Impact of GPS loss on time drift and measurement error (Aug 2015)

– GPS loss distribution in relation to time and location (Oct 2015)

4

Risks and Thoughts for Future

• Risks or uncertainties - No known risks or uncertainties

• Early thoughts on follow-on work

– Impact of communication delay (FY16)

– Impact of data loss (FY16)

– Evaluate the benefit of increased data reporting rate (FY17)

– Re-visit the distribution level measurement accuracy limits (FY17)

5

Selected Applications

• PMU applications for this study

Event

Location

Oscillation

Detection

Islanding

Detection

Dynamic

Line Rating

6

Error Sources Used in the Study

• PMU Error

− IEEE Std C37.118.1-2011, C37.118.1a-2014

− Phase angle: 0.57° ( 0.6°) based on 1% TVE

− Frequency error: 0.005 Hz

• Instrument Channel Error

− PT, CT, CCVT, Cable

combined error

− -0.2 to -1.0 for most cases*

*A. P. Meliopoulos, et al. , Synchrophasor Measurement Accuracy Characterization, NASPI Performance & Standards Task Team, 2007, pp. 43-58.

7

Methodology

• Assumption

o Frequency error: ±0.005 Hz (most PMUs are better)

o Angle error

− PMU part : ±0.6 (most units are better)

− Instrumentation channels -1.0 (maximum) This number varies with installation situation and impacts only applications using absolute angles.

• Approach o Assume the maximum error

o Find the worst case

8

Angle-Based Event Location

0 1 2 3 4 5 6 7 8 9 10 11 120

10

20

30

40

50

60

70

Time (s)

An

gle

(d

eg

re

e)

2010/01/03 13:03:43(UTC) Generation Trip

CaMbWinnipeg665

UsCtDanbury666

UsFlUfl663

UsIlChicago620

UsMaBoston684

UsMaNeiso682

UsMiCalvin679

UsMiWayneState621

UsMoKansasCity616

UsMoMst624

UsMsMissi662

UsNjNerc678

UsNyLeroy667

UsOhChillicothe670

UsOhColumbus687

UsTxTexasTech683

UsVaAri661

UsVaBlacksburg656

UsVaNewportNews668

UsVaRichmond601

UsVaRvcs686

UsWiMadison649

UsWvCharleston688 : first responding FDR

: event location range

: possible power plants

9

How Error Impact the detection order

• An Example

Time (s)

An

gle

(d

eg

ree

)

2010/03/12 09:02:35(UTC) Generation Trip

5 5.5 62.2

2.4

2.6

2.8

3

3.2

3.4

3.6

3.8

4

4.2

UsWvCharleston688

UsVaBlacksburg656

UsVaRvcs686

UsVaRichmond601

UsOhColumbus687

UsOhChillicothe670

Time (s)

An

gle

(d

eg

ree

)

2010/03/12 09:02:35(UTC) Generation Trip

5.5 62.2

2.4

2.6

2.8

3

3.2

3.4

3.6

3.8

4

4.2

UsWvCharleston688

UsVaBlacksburg656

UsVaRvcs686

UsVaRichmond601

UsOhColumbus687

UsOhChillicothe670

±0.6° error

10

Most Scenarios Unaffected

11

Oscillation Detection: Approach

• Phase angle based two-threshold method

Th1

|A(max)-A(min)|>Th2

5 S

12

Islanding Detection: Frequency Based

5 10

59.3

59.4

59.5

59.6

59.7

59.8

59.9

60

Time(min)

Fre

qu

en

cy

(Hz)

Islanding Unit

On Grid Unit 1

On Grid Unit 2

On Grid Unit 3

On Grid Unit 4

Islanding

Taking

Place

Islanding Generation Trip

Error may affect accuracy if < 1 second detection time is required at 30p/s rate. Time delay is required for false event rejection.

13

PMUPMU DLR

Is Ir

VrVs

Z

jB jB

Vr, IrVs,Is

Bus i Bus j

Dynamic Line Rating

• PMUs provide V and I phasors on both ends

• Consider only angle error in V and I

• Algorithm shown in references below

1. IEEE, “IEEE Standard for Calculating the Current-Temperature Relationship of Bare Overhead Conductors”, IEEE Std 738-1993

2. Sveinn Rúnar Júlíusson, “Using PMU Measurements to Assess Dynamic Line Rating of Transmission Lines”, Aalborg University, 2013

3. J. Zhao, J. Tan, L. Wu, L. Zhan, et al., “Impact of Measurement Error on Synchrophasors Applications”, Oak Ridge National Laboratory, 2015

14

Influence of Different Factors

Wind Speed Ambient Temperature

Solar Heat

15

Error Impact

Summer

Errmax:45.87%

Te

mp

era

ture

(°C

)

-10

0

20

30

40

50

10 Win

d S

pe

ed

(m

/s)

0

2

8

10

14

16

6

4

12

So

lar

He

at

(W/m

)

0

5

20

25

35

40

15

10

30

Temperature

Solar Heat

Wind Speed

Dynamic Line Rating

Time of the Day

Dynamic Line Rating

Time of the Day

Error Band

16

Conclusion

Application Effect Significance

Event location

A small number of cases show impact

Minor impact

Oscillation detection

Problem only for small magnitude cases

Threshold dependent

Islanding detection

Safe for detection time > 1 second

Detection time dependent

Dynamic line rating

Potential to introduce large errors

Very sensitive

17

Additional Information

18

Event Location: A Brief Introduction

• Angle-Based Event Location

: first responding FDR

: event location range

: possible power plants

19

Impact of Error Depends on Thresholds

• False detection

Time

An

gle

Time Window

Time A

ngle

Time Window

Th2

No Error With Error

20

Impact of Error Depends on Thresholds

• Failed detection

No Error

Time

An

gle

Time Window

Th2

Time A

ngle

Time Window

With Error

21

Error Impact

Winter

Errmax:22.87%

Tem

per

atu

re (

°C)

-10

0

20

30

40

50

10 Win

d S

pee

d (

m/s

)

0

2

8

10

14

16

6

4

12

Sola

r H

eat

(W

/m)

0

5

20

25

35

40

15

10

30

TemperatureSolar Heat

Wind Speed

Dynamic Line Rating

Time of the Day

Dynamic Line Rating

Time of the Day

Error Band