impact on power system components · i-pcgrid workshop 2015, sf, ca –march 25-27, 2015 page 5...

i-PCGRID Workshop 2015, SF, CA – March 25-27, 2015

Geomagnetic Disturbances:

Impact on Power System

Components

Sakis Meliopoulos

Georgia Power Distinguished

Professor

School of Electrical and

Computer Engineering

Georgia Institute of

Technology

Atlanta, Georgia


GIC Physics DC like currents in soil up to 10V/km

Corona Mass Ejection MagnetoSphere Interaction


Characteristics of Magnetic and Electric Field

From “Effects of Geomagnetic Disturbances on Electric Power Systems”, EPRI Report EL-7333, August 1991, by A. P. Sakis Meliopoulos et al.

Levels of magnetic field and rate of change of magnetic field makes the electric field appear as DC for the electric power system


Magnetic and Electric Field Exist Always and

Increase Drastically During Storms

1

1

2

2

3

3

4

4

5

5

6

6

7

7

A A

B B

C C

D D

E E

Advanced Grounding Concepts / WinSGM

August 11, 2004 Tooele Location

Step Voltage Measurement Setup

Scale (feet)

0' 45' 90' 135'

CR

3Y

2Y

1Y

3B

2B

1B

N

N39 24.344'0

W112 35.985'0

P1

P2

P3

P4P5

P6

P0SGM Location

219'

X

YGrid Spacing: 500.0 ft

Model A (Biquadratic)

Node Indexing DiscretizationExample earth surface voltage

measurements near Toole, UT

Indicates max voltages of about 2 V/mi

K-index not reported

-120.00

-100.00

-80.00

-60.00

-40.00

-20.00

0.00

20.00

1 2 3 4 5 6

Ste

p V

oltage (

mV

)

Probe Number

0 A (18:27)

100 A (18:45)

-100 A (19:04)

0 A (19:22)


Impact on Power System Components

Main Issues of Concern:

DC injection into Saturable Core Power Apparatus

Results into Current Distortion, Harmonics and Consequences

Vulnerable Power Equipment

Saturable Core Power Apparatus

• Generators: typically grounded via high impedance – secondary

concerns

• Solidly grounded transformers (two/three/four winding,

autotransformers)

• Solidly grounded saturable core reactors


Applicable Circuit for GIC – DC OnlyMagnetic Saturation Characteristics

DC Equivalent Circuit of Line Terminated to Transformers


Investigations Findings

Magnetic Saturation Characteristics

Typical Iron Core Magnetization Curve


Impact on DC Current Injection To TransformersMain Issues of Concern: Transformer/Reactor Saturation - Harmonics

Harmonic Currents on the 500 kV Side of a 360 MVA, 500/230 kV Transformer

with 75 A DC Injection

From “Mitigation of Geomagnetically Induced and DC Stray Currents”, EPRI Report EL-3295,

December 1983, by J. G. Kappenman, et al.


The Effects of the March

13, 1989 Storm Felt as

South as New Jersey

Magnetic Field: ~1500 nT/min

http://www.windows2universe.org/space_weather/sw_in_depth/images/transformer_damaged_big_jpg_image.html

http://www.windows2universe.org/space_weather/sw_in_depth/images/transformer_damaged_big_jpg_image.html


Vulnerabilities Studies / Model Requirements

Modeling Issues

The main mechanism of DC current entry into saturable

core electrical equipment is via the grounding system of

substations and transmission lines


Vulnerability Studies / Modeling RequirementsFrequency Dependence of Line Parameters

Line Model

G. J. Cokkinides and A. P. Meliopoulos, "Transmission Line Modeling with Explicit Grounding

Representation," Electric Power Systems Research, vol. 14, no. 2, pp. 109-119, April 1988.


Example Parametric Study

Magnetic Saturation Characteristics

Steady State Direct Current through Transformer Winding

From “Effects of Geomagnetic Disturbances on Electric Power Systems”, EPRI Report EL-7333, August 1991, by A. P. Sakis Meliopoulos et al.


Example Simulation Results / Vulnerability StudyMain Issues Concern: Transformer/Reactor Saturation – Simulations

G12

V

V

V A

A

A

1 2

G

V

V

V

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

BU

S230A

BU

S230B

BU

S230B

B

BU

S230M

ID

GIC

2

GIC

MID

SO

UR

CE

1

SO

UR

CE

2

XFM

R1

XFM

R2


Vulnerabilities Studies / Focus Systems

Vulnerable System

Non-Vulnerable System

Non-vulnerable/vulnerable system / Series Compensated Line


Impact on Generators

Main Issues Concern:

Generator –Simulations

G12

V

V

V A

A

A

1 2

G

V

V

V

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

BU

S230A

BU

S230B

BU

S230B

B

BU

S230M

ID

GIC

2

GIC

MID

SO

UR

CE

1

SO

UR

CE

2

XFM

R1

XFM

R2

Generator Grounded with 1000 ohm Resistor

DC Current in Transformer Neutral: 80A

Generator Neg Seq Current: 138 A peak

Generator current THD: 8.4%

-73.55 A

-86.62 A

Neutral_DC_Current (A)

133.0 A

-138.0 A

Current_Negative_Sequence (A)

26.93 mA

-28.10 mA

Current_Zero_Sequence (A)

8.510 %

8.155 %

Current_THD_Phase_A (%)

39.31 ms 0.226 s


Impact on Generators

Main Issues Concern:

Generator –Simulations

G12

V

V

V A

A

A

1 2

G

V

V

V

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

BU

S230A

BU

S230B

BU

S230B

B

BU

S230M

ID

GIC

2

GIC

MID

SO

UR

CE

1

SO

UR

CE

2

XFM

R1

XFM

R2

-73.49 A

-79.54 A

Neutral_DC_Current (A)

133.0 A

-138.1 A

Current_Negative_Sequence (A)

27.79 mA

-26.69 mA

Current_Zero_Sequence (A)

8.512 %

8.343 %

Current_THD_Phase_A (%)

38.36 ms 0.125 s

Generator Grounded with 10 ohm Resistor

DC Current in Transformer Neutral: 80A

Generator Neg Seq Current: 138 A peak

Generator current THD: 8.4%


Mitigation Methods / Effectiveness

• Early Warning Systems

• Monitoring / Alarming Systems

• DC Block Systems

• Resistance Grounding



Important function of SOHO: Geomagnetic Storm Strength Measurement

Transmits K - Index

The “K-Index” is a 3-hourly quasi-logarithmic local index of geomagnetic

activity relative to an assumed quiet-day curve for the recording site.

Range is 0 to 9

The K-Index measures the deviation of the most disturbed horizontal

component of the magnetic field.

Active: K=4, Minor Storm: K=5, Major Storm: K=6 or higher

Warning Systems


Mitigation Methods / EffectivenessMonitoring / Alarming Systems

I

Global Time

Reference

(GPS)

GPS

Receiver

Micro

processorA/D

Phasor data

(time stamped)Serial

Communication

Port

Filt

er

To Control Center

Harmonics Data

Concentrator

(Located in Atlanta)

PMU Block Diagram

V

GPS Antena

ADD Bulletin

Board System

GIC Data

Concentrator

Located at NYPP

PMU

Computer

PMU

Computer

PMU

Computer

Asymmetric Power System Model

New York Power Authority

NYPA Project Launched: 1993, Completed: 1998, Meliopoulos & Cokkinides

This System is Presently Operational

and Participates in the North American

SynchroPhasor Initiative (NASPI)

MACRODYNE

PMU, 1992First Device Capable of

Synchronized

Measurements with

accuracy of

microsecond

Macrodyne PMU Based Harmonic

Measurement System

B. Fardanesh, S. Zelingher, A. P. Sakis Meliopoulos, G. Cokkinides and Jim Ingleson, ‘Multifunctional Synchronized

Measurement Network’, IEEE Computer Applications in Power, Volume 11, Number 1, pp 26-30, January 1998.



Harmonic Monitoring

• Harmonic Signature Due to GIC

• Neutral DC Monitoring - Hall Effect CT

Macrodyne PMU Based Harmonic Measurement System Detects GIC by:

(a) harmonic signature and

(b) neutral direct current measurement

B. Fardanesh, S. Zelingher, A. P. Sakis Meliopoulos, G. Cokkinides and Jim Ingleson, ‘Multifunctional Synchronized Measurement Network’, IEEE Computer Applications in Power, Volume 11, Number 1, pp 26-30, January 1998.


Mitigation Methods / EffectivenessDC Blocking Devices


Mitigation Methods / EffectivenessResistance Grounding


Thank you for your Attention

Questions?

impact on power system components · i-pcgrid workshop 2015, sf, ca –march 25-27, 2015 page 5...

Documents