Armien EdwardsChief EngineerEskom - SO&PSouth Africa

Eskom Wide Area Monitoring System

2

Enabling Technologies

•GPS technology

•IP Based Telecommunications networks

•Highly accurate IEDs in substations–Phasor Measurement Units

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GISIntelligentSwitchgear

ITV（（（（ ））））

【【【【 】】】】

WAN

IED

3

Synchronised Phasor Measurements

4

PMU vs SCADA

ATTRIBUTE SCADA SYNCHONISED PHASOR

Resolution2-4 samples per sec

Up to 50/60 samples per sec

Observability Steady State Dynamic/Transient

Monitoring Local Wide-Area

Phase Angle Measurement

No Yes

Measured Quantity

Magnitude –

(RMS) – MW,

MVAR

Magnitude (RMS) and

phase offset from common

reference – MW, MVAR,and

Angle Difference

frequency

5

PMU vs SCADA

Pegasus Busbar Voltage (PMU vs SCADA Data)

360000

370000

380000

390000

400000

410000

06:3

0:00

.000

06:3

0:07

.720

06:3

0:15

.440

06:3

0:23

.160

06:3

0:30

.880

06:3

0:38

.600

06:3

0:46

.320

06:3

0:54

.040

06:3

1:01

.760

06:3

1:09

.480

06:3

1:17

.200

06:3

1:24

.920

06:3

1:32

.640

06:3

1:40

.360

06:3

1:48

.080

06:3

1:55

.800

06:3

2:03

.520

06:3

2:11

.240

06:3

2:18

.960

06:3

2:26

.680

06:3

2:34

.400

06:3

2:42

.120

06:3

2:49

.840

06:3

2:57

.560

06:3

3:05

.280

06:3

3:13

.000

06:3

3:20

.720

06:3

3:28

.440

06:3

3:36

.160

06:3

3:43

.880

06:3

3:51

.600

06:3

3:59

.320

06:3

4:07

.040

06:3

4:14

.760

06:3

4:22

.480

06:3

4:30

.200

06:3

4:37

.920

06:3

4:45

.640

06:3

4:53

.360

Time

Vo

ltag

e (V

)

PMU Data

SCADA Data

6

System Overview for WAMS

Wide Area Ethernet in the Substation

PMUData

Storage

EIA232 or 485

PMUEthernet

PC37.118

PhasorData Conc.

EthernetPC37.118

EthernetC37.118 Local

Operation

NationalOperations

Other Utilities

Substation IP Access

Security Issues

DedicatedIP Network

DedicatedIP Network

Internetor

VPN

7

Wide Area Monitoring Applications for the Control Centre

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Situational Awareness

Global display-an alarm overview display

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Model Validation

Frequency

MW

MW

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Power system oscillations

Power swings of up to 100MW

11

Dynamic Data Visualisation

Overview display for modal analysis

12

Small Signal Stability Analysis

13

Small Signal Stability Analysis

Poor damping of the 0.93Hz mode

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Offline model validation

2.0000-0.4000-2.8000-5.2000-7.6000-10.000 Neg. Damping [1/s]

7.6932

6.1546

4.6159

3.0773

1.5387

Damped Frequency [Hz]

Stable EigenvaluesUnstable Eigenvalues

DIg

SIL

EN

T

15

Eskom WAMS Project

16

User Requirements

Short Term (Phase 1)1-3 years

Medium Term3-5 years

Long Term> 5 years

Situational Awareness –Angle/Frequency Monitoring/Damping

Situational Awareness –Advanced Visualization Tools

State Measurement (Linear)

Post Event Analysis Model Benchmarking; Parameter Estimation

Real-Time Control

State Estimation (Improve) State Estimation (hybrid system)

Adaptive Protection

Model Benchmarking; Parameter Estimation

Advanced stability monitoring applications

WA Stabilization (WA-PSS)

Power System Restoration Planned Power-System Separation – Special Protection Systems

Small signal Stability monitoring applications

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PMU Locations• Feeders key to the interconnection between grid regions

• Nodes that exhibit large shifts in power anglebased on a loss of generation, load and change in topology

• Areas of interest from a load modellingperspective

• Areas of the grid with known dynamic stabilityissues

• Areas that can form frequency islands

• Areas of the grid prone to voltage collapse

• Nodes beneficial for the current state estimator improvement and a future linear state estimator

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PMU Locations

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System Architecture

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Conclusions• Synchronised phasor technology is an essential component of a ‘smart’ transmission grid

• Application benefits can be realised with immediate effect

• New visualisation and analysis tools provides the ability to operate the power system confidently under stressed conditions

• Although an independent system today, it will eventually migrate into the standard substation SCADA architecture