EEL / UFSC

The Brazilian Wide Area Measurement System – Experience and Applications

Daniel Dotta

email: dotta@ifsc.edu.br

EEL / UFSC

Objective Wide Area Measurement System Overview Phasor Measurement Process

– Research going on at RPI The MedFasee Project

– LVPMS and HVPMS prototypes Blackout in the Brazilian Interconnected Power

System Selected Applications Conclusions

Presentation Structure

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To present an overview of the Brazilian experience with Wide Area Measurement Systems

Objective

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Wide Area Measurement System - WAMS

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Wide Area Measurement SystemOverview

5

Simultaneous signals measurements at remote geographic locations using PMUs (Phasor Measurement Units).

GPS time synchronized measurements Data acquisition and handling in remote sites (PDC). Upgrade rate (scanning) >> SCADA. Allows dynamic monitoring and

control of electric systems. New paradigm for the system

operation.

EEL / UFSCPhasor Definition Complex number that represents a sine wave whose amplitude

(X) and angular frequency (ω) are time-invariant

The phasor module is equal to the rms signal value and the phase angle is the signal phase to t=0.

max 0

max

( ) cos( )

where 2

x t X tXX

X

6

EEL / UFSCSynchrophasors Phasor measurements that occur at same time are

called “synchrophasors”.

Task not trivial: Involves large distances and high time precision. 7

Necessity of only one time reference – Synchronization!

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Update rate: 30-60 phasors per second

Time synchronized data High-speed communication

links Allows the dynamic system

monitoring

Update rate: each 2-5 seconds

No time synchronization Regular communication links

Allows stead-steaty system monitoring

SCADA(Supervisory Control and Data

Acquisition)

WAMS(Wide-Area Measurement System)

SCADA X WAMS(Comparasion)

8

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By SCADA By WAMS

How can the power system be seen?

9

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Phasor Measurement Process

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Basic Phasor Measurement Process Idea

Sine WaveWindow Size (points)

sf NfSampling rate

For N=12

0.014 0.016 0.018 0.02 0.022 0.024 0.026 0.028 0.03 0.032-1.5

-1

-0.5

0

0.5

1

1.5

Time(s)

Mag

nitu

de (p

u)

Time-Domain Signal

1/fs

N=12

12N

Sampling period1

ss

Tf

Regular sampling period (Ts)

12 60 720sf Hz 0.0014sT s

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Basic Phasor Measurement Process Idea

Time Domain Frequency Domain

( )n nx x tSamples

, 0, , -1n st nT n N

( )mjmX X e

2 , 0, , -1m m m NN where

DFT

0.014 0.016 0.018 0.02 0.022 0.024 0.026 0.028 0.03 0.032-1.5

-1

-0.5

0

0.5

1

1.5

Time(s)

Mag

nitu

de (p

u)

Time-Domain Signal

1/fs

N=12

12N

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Definition of DFT

Discrete Fourier Transform is a simple widely used method for phasor estimation

– Other methods have been discussed » Kalman filters, weighted least squares and neural networks

– Currently used in the commercial PMUs

Phasor Estimation

21

0

2 N j nmN

m nn

X x eN

21

0

2 N j nN

nn

X x eN

Fundamental frequency component, set m=1

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Basic Phasor Measurement Architectures

Frequency Tracking Frequency Compensation

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Composed basically by– Analogic and digital filters– Phasor Estimation Methodology – Frequency Estimation Methodology

The most explored and applied is the frequency compensation architecture– Basically because use uniform sampling period

Basic Phasor Estimation Architecture

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Frequency Estimation is a key role in the both architectures– Changing the sampling window– Providing the frequency for phasor correction

Several methods are found in the literature– Zero Crossing– Least Error Squares– Kalman Filters– Demodulation– Phasor measurement angle changing

Frequency Estimation (Methodologies)

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Under off-nominal operation the phasor measured (Xmes) is different from the true value (Xtrue)– The effect of the off-nominal frequency can be expressed

by a P factor.

Pos-Processing(Off-nominal Frequency)

where

N - window sizew – actual frequencyw0 – nominal frequency

truemesX PX

00 ( )

( 1)2

0

( )sin2{ }( )sin2

tj N

N t

P etN

Phasor correction

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The P factor is directly influence by N and frequency value P behavior under frequency variation (N=48)

Pos-Processing(Off-nominal Frequency)

-5 -4 -3 -2 -1 0 1 2 3 4 50.985

0.99

0.995

1

1.005

-5 -4 -3 -2 -1 0 1 2 3 4 5-20

-10

0

10

20

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Frequency step (off-nominal operation)

Phasor Estimation (Discrete Fourier Transform)

0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4-20

-10

0

10

20Phase A - Signal Input

Mag

nitu

de (p

u)

0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.458.8

59

59.2

59.4

59.6

59.8

60

60.2

Time(s)

Freq

uenc

y (H

z)

Signal Frequency

EstimatedReal

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Sequence positive phasor estimation

Phasor Estimation (Discrete Fourier Transform)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 211.308

11.31

11.312

11.314

11.316

Mag

nitu

de (p

u)

Magnitude Positive Sequence

Without Calibration FactorWith Calibration Factor

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-200

-100

0

100

200

Time(s)

Deg

ress

Angle Positive Sequence

Before CorrectionAfter Correction

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MedFasee Project

EEL / UFSC

Brazilian Interconnected Power System - BIPS

Main Characteristics– Capacity of about 100 GW– Predominant hydroelectric

generation (about 71 %)– 90000 km of transmission

lines, with voltages ranging from 230 kV to 765 kV

– The largest powerplant, Itaipu, has 20 generators with a generation capacity of 14 GW, half in 60 Hz and half in 50 Hz

– Composed by 5 subsystems

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Project started in 2003 – The main goal was to develop the synchronized phasor

measurement technology in Brazil and study its applications

It resulted in two prototypes currently installed in Brazil:– LVPMS (Low Voltage Phasor Measurement System).

– HVPMS (High Voltage Phasor Measurement System).

The MedFasee R&D Project

EEL / UFSC

Medfasee Project(First Prototype)

Three PMUs were installed in laboratories of three universities in Southern Brazil

The PMUs measure the instantaneous three-phase distribution voltage

The PMUs have a network interface connected to the Internet to send the phasors to the PDC– 60 phasors/s

The PDC is located in the Electrical System Planning Research Laboratory (LabPlan) at UFSC

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PMU UTFPR

PMU PUC – RSPMU e PDC LabPlan – UFSC

MedFasee Project – Low VoltagePrototype Installation Details

25

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a) Frequency Evolution: b) Frequency Spectrum

System frequency oscillation mode ~ 0,02 Hz (period 50s).

Frequency Monitoring (12/01/2005) 15h00min00s e 15h29min59s)

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Firsts Disturbances Disturbance Southeast / Mid-West (14/03/2005 – 05h05min12s)

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MedFasee Low Voltage Phase II - National WAMS

Characteristics Develop, dissemination and educational use of

the WAMS technology Nine universities participate in the project Five geographical regions are covered Internet is used as commutation link

28

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Source: www.medfasee.ufsc.br/temporeal

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PMU UFSC – Florianópolis, SC– Installation Date: 30/11/2008

MedFasee LV - Installations

30

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PMU UFPA, Belém, PA– Installation Date: 06/11/2008

31

MedFasee LV - Installations

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COPPE/UFRJ, Rio de Janeiro, RJ– Installation Date: 18/12/2008

32

Phase II -> Conclusion

MedFasee LV - Installations

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Hardware:– DELL OptiPlex 755 – Core 2 Duo 3GHz, 2GB RAM,

2000 GB HD Software:

– Operation System - GNU/Linux + (RTAI)

– Oriented Object Modeling (C/C++)

– MySQL Database– Long-term historical database

Communication System:– Internet (VPN)

MedFasee LVPDC Installation - UFSC

33

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MedFasee LV– Phase IIINational Wide Area Measurement System

34

Characteristics Improve the national system coverage 14 universities involved West BIPS monitoring

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Source: www.medfasee.ufsc.br/temporeal

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HVPMS(High Voltage Phasor Measurement System)– The HVPMS resulted from a

partnership with Eletrosul, a transmission utility in Southern Brazil

– Four PMUs, installed at Ivaiporã, Areia, Campos Novos and Nova Santa Rita 525 kV substations

– Voltage and current phasors are sent to the PDC at a rate of 60 data frames per second

– It has been monitoring eight transmission line terminals with two transmission lines having PMUs in both terminals

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MedFasee Project EletrosulPMUs

Digital Fault Recorder with PMU functionality

2 RPV 304 + 2 RPV 310 Standard IEEE C37.118 Rate 60 phasor/second - 3Ф Link Ethernet and UDP/IP protocol Configurable to 10, 12, 15, 20, 30 e 60

phasors/s e positive sequence

RPV 304

RPV 31037

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Projeto MedFasee Eletrosul PDC

Characteristics: PC architecture GNU/Linux + (RTAI) operational system Object Oriented Modeling (C/C++) MySQL Database

Features: Receiving, handling and re-

synchronization of phasors Centralized data available and storage Support for off-line analysis 15 days historical database

Hardware:• Core 2 Duo 3GHz• 2 GB RAM• 250 GB HD

38

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An event, on March 21, 2009, is used to illustrate the correlation between the LVPMS and the HVPMS

Event Description– 525 kV transmission line Lajeado-Miracema tripped;

– 900 MW generator shedding at Lajeado hydroelectric power plant;

Data Correlation(LVPMS X HVPMS)

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LVPMS x HVPMS(Frequency Behavior)

LVPMS HVPMS

High correlation between the recorded data

0 50 100 150 200 250 30059.7

59.75

59.8

59.85

59.9

59.95

60

60.05

60.1

Freq

uenc

y (H

z)

Time (seconds) - Start: March 21, 2009 12:20:00 (local time)

UFPAUFCUnBUSP-SCUNIFEIUFRJUFSC

0 50 100 150 200 250 30059.7

59.75

59.8

59.85

59.9

59.95

60

60.05

60.1

Freq

uenc

y (H

z)

Time (seconds) - Start: March 21, 2009 12:20:00 (local time)

IvaiporãAreiaN.S.Rita

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LVPMS x HVPMS(Angle Difference and Power Flow)

80 85 90 95 100 105 11049.5

50

50.5

51

51.5

52

Ang

le D

iffer

ence

(Deg

rees

)

Time (seconds) - Start: March 21, 2009 12:20:00 (local time)

80 85 90 95 100 105 1101090

1095

1100

1105

1110

1115

1120

1125

1130

Pow

er F

low

(MW

)

Time (seconds) - Start: March 21, 2009 12:20:00 (local time)

0.2 0.4 0.6 0.8 1 1.2 1.4 1.60

0.02

0.04

0.06

0.08

0.1

0.12

0.14

Frequency (Hz)

Ang

le D

iffer

ence

Mag

nitu

de (D

egre

es)

0.37Hz

0.69Hz0.87Hz

0.2 0.4 0.6 0.8 1 1.2 1.4 1.60

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Frequency (Hz)P

ower

Flo

w M

agni

tude

(MW

)

0.87Hz0.69Hz

0.37Hz

Angular Difference

UFSC (South) – USPSC

(Southeast)

LVPMS

HVPMS

Power FlowTL Ivaiporã-

AreiaFrequency SpectrumIvaiporã is an Interconnection point between

Southern and Southeastern regions

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BIPS Blackout(November 10, 2009)

– At 10:13:06 (PM), local time, the three 765 kV (AC) transmission lines that connect ITAIPU power plant to the BIPS tripped

– The fault was caused by a sequence of three single-phase short-circuits in different phases, near Itaberá substation

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Itaipu real time operation

BIPS Blackout(November 10, 2009)

The Itaipu power plant was operating with 18 generators, with a 5560 MW power flow over the AC link and a 5329 MW power flow over the HVDC transmission system

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Sequence and consequences of the Blackout

BIPS Blackout(November 10, 2009)

Disconnection of the Itaipu AC transmission system Overloading and tripping of transmission lines interconnecting

the Southern and Southeastern subsystems After two seconds, a cascating outage of power plants and

transmission lines in the Southeastern region led to a voltage collapse and the tripping of the HVDC link

The disturbance spread to other parts of the BIPS The blackout resulted in the interruption of approximately 25

GW, 40% of BIPS total load

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Recorded by the LVPMS– Voltage dipping, following the outage of the Itaipu AC

transmission system and the South-Southeastern interconnections.

BIPS Blackout(November 10, 2009)

185.5 186 186.5 187 187.50.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

Vol

tage

(PU

)

Time (seconds) - Start: Nov. 10, 2009 22:10:00 (local time)

UFPAUNIFEIUnBCOPPEUSP-SCUTFPRUFSCPUC-RS

Voltage Collapse

Southeastern subsystemUSP-SC, COPPE and UNIFEI

The voltages recover in the South (PUCRS,

UFSC and UTFPR)

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BIPS Blackout(Recorded by the LVPMS)

180 200 220 240 260 280 300 32058

59

60

61

62

63

64

Freq

uenc

y (H

z)Time (seconds) - Start: Nov. 10, 2009 22:10:00 (local time)

UFPAUnBUTFPRUFSCPUC-RS

Electromechanical oscillations

180 200 220 240 260 280 300 3200.9

0.95

1

1.05

1.1

1.15

1.2

Vol

tage

(PU

)

Time (seconds) - Start: Nov. 10, 2009 22:10:00 (local time)

UFPAUnBUTFPRUFSCPUC-RS

Frequency excursions after the outage of the main South-Southeast interconnection

Voltage

HVPMS – Active Power Flow

180 200 220 240 260 280 300 320-1000

-500

0

500

1000

1500

2000

Pow

er F

low

(MW

)

Time (seconds) - Start: Nov. 10, 2009 22:10:00 (local time)

The 525 kV transmission line (Assis–Araraquara) keeps the Southern and Southeastern regions connected for 1min20s

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Asynchronous operation

BIPS Blackout(Recorded by the LVPMS )

LVPMS – Zoom in asynchronous operation

186 188 190 192 194 196 198 200 20258

59

60

61

62

63

64Fr

eque

ncy

(Hz)

Time (seconds) - Start: Nov. 10, 2009 22:10:00 (local time)

UFPAUnBUTFPRUFSCPUC-RS

63.6 Hz (Max)South

58.6 Hz (Min)North

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First South-Southeast reconnection– At 01:43:50 (AM), the first attempt to reclose de

interconnection

BIPS Blackout(Recorded by the LVPMS)

Frequency Frequency Spectrum –North-South Mode

215 220 225 230 235 240 245 250 255 260 26559.94

59.96

59.98

60

60.02

60.04

60.06

60.08

60.1

Freq

uenc

y (H

z)

Time (seconds) - Start: Nov. 11, 2009 01:40:00 (local time)

UFPAUNIFEIUnBUTFPRUFSCPUC-RS

0.2 0.4 0.6 0.8 1 1.2 1.4 1.60

1

2

3

4

5

6

7

8x 10

-3

Frequency (Hz)

Freq

uenc

y M

agni

tude

(Hz)

UFPAUNIFEIUnBUTFPRUFSCPUC-RS

0.25Hz

EEL / UFSC

The data captured by the both systems were very important to elucidate the Brazilian Blackout

Since than, the National System Operator have been use the Medfasee data to post-mortem disturbance analysis– Decrease the time spend in post-mortem analysis

BIPS Blackout(November 10, 2009)

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Selected Applications

Low-frequency oscillation mode detection Model Validation Transmission Line Parameters Calculation Small-signal control

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Model ValidationSelected Study

51

BIPS disturbance 04/07/2009

Registers: MedFasee LV MedFasee Eletrosul

Simulation Model: Anatem/CEPEL

Validation Analysis Qualitative Validation Quantitative Validation

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Qualitative ValidationFrequency Signal Assessment

52

Medição - BT

Simulação - BT

0 1 2 3 4 5 6 7 8 9 10

59

59.2

59.4

59.6

59.8

60

Frequência medida SPMS BT

Freq

uênc

ia (H

z)

Tempo(s) - 04/07/2009 - 18:36:37,15 (Local)

UnBUFC USP-SCPUC-RS

0 1 2 3 4 5 6 7 8 9 10

59

59.2

59.4

59.6

59.8

60

Tempo(s) - 04/07/2009 - 18:36:37,15 (Local)

Freq

uênc

ia (H

z)

Frequência simulada SPMS BT

UnB - (B.SUL)UFC - (Fortaleza)USP-SC - (São Carlos)PUC-RS - (Porto Alegre)

0 1 2 3 4 5 6 7 8 9 10

59

59.2

59.4

59.6

59.8

60

Frequência medida SPMS AT

Freq

uênc

ia (H

z)

Tempo(s) - 04/07/2009 - 18:36:37,15 (Local)

IvaiporãCampos NovosNova Santa Rita

0 1 2 3 4 5 6 7 8 9 10

59

59.2

59.4

59.6

59.8

60

Tempo(s) - 04/07/2009 - 18:36:37,15 (Local)

Freq

uênc

ia (H

z)

Frequência simulada SPMS AT

IvaiporãCampos NovosNova Santa Rita

Measured Simulated

LV

HV

EEL / UFSCReal Time Spectral Analysis

53

MDF Real-time applications Off-line applications

EEL / UFSCConclusions The MedFasee project involves the development of equipment,

installation, operation and performance analysis of Wide Area Measurement System (WAMS)

It is possible to get important information on the power system dynamic performance from the low-voltage WAMS.

The MedFasee project has been a rich experience and has contributed to the development and dissemination of WAMS technology in Brazil .

The WAMS represents a paradigm change in the power system monitoring

The WAMS measurement process must be simple and understandable for power system engineers

Improve the application of signal processing techniques in power system

EEL / UFSCThank you! Daniel Dotta

– Department of Electrical Engineering – EEL– Federal Institute of Santa Catarina – IFSC– E-mail: dotta@ifsc.edu.br– RPI contact– E-mail: dottad@rpi.edu– Linkedin– http://www.linkedin.com/pub/daniel-dotta/11/79a/85b