Synchrophasor Technology – Devices (PMUs) and Applications · PDF fileSynchrophasor Technology – Devices (PMUs) and Applications Saugata S. Biswas PhD Candidate working with Prof

Synchrophasor Technology –Devices (PMUs) and Applications

Saugata S. BiswasPhD Candidate working with Prof. Anurag Srivastava

The School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA-99164, USA

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Outline

Motivation for Synchrophasor Technology

o Power System Operational Paradigm

o Motivation for Synchronized Measurements

Synchrophasor Fundamentals

o Synchrophasor Definition & Need

o Introduction to Phasor Measurement Unit (PMU)

o PMU Installations and Standards

Synchrophasor Device Testing

Synchrophasor Technology Applications

o Different Applications of Synchrophasor Technology

o One Typical Application: System Voltage Stability Analysis

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Outline












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SenseC

omm

unic

ate

Compute, Monitor and send Control Signals

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Power System Operational Paradigm

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Motivation for Synchronized Measurements:Instrumentation without PMU

Motivation for Synchronized Measurements:Current and Voltage Measurements

• Measurements from CT/ PT: 3 phase sinusoidal AC voltages and currents at a frequency of 60 Hz

• Phase ‘a’ quantities (voltages and currents) lead phase ‘b’ quantities by 120 degrees, which leads phase ‘c’ by 120 degrees (depending on phasor rotation practice)

phase ‘a’

phase ‘b’

phase ‘c’

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• Measured values sampled generally every 4-6 seconds are displayed on the Energy Management System (EMS) screens

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• System monitoring is more critical during disturbance and transients

• Faster synchronized data is needed to capture the dynamics

• Fast real time control is possible only with real time situational awareness

Motivation for Synchronized Measurements:Need for High Resolution Synchronized Data

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9At some substation in California At some substation in Washington

Providing Time Reference for Phasor Measurements

Motivation for Synchronized Measurements:Need for Wide Area Synchronized Phasors

• Time synchronized wide area measurements are not available from SCADA.

• Angle Measurements are not available from SCADA

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It’s like going from ‘still photography of sections of the power systemwith limited time synchronization’ to ‘video photography of the entirepower system in a time synchronized manner’.

Motivation for Synchronized Measurements:An Analogy for SCADA v/s Synchrophasor Technology

Outline












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• The concept of using phasors to describe power system operating quantities dates back to 1893 and Charles Proteus Steinmetz’s paper on mathematical techniques for analyzing AC networks.

• More recently, Steinmetz’s technique of phasor calculation has evolved into the calculation of real-time phasor measurements synchronized to an absolute time reference.

• Although phasors have been clearly understood for over 100 years, the detailed definition of a time-synchronized phasor has only recently been codified in the IEEE C37.118

• Synchronized measurements made possible by Global Positioning System (GPS) satellites

• Development of the first PMUs at Virginia Tech ~ 1982-1992 by Professor Arun Phadke, funded by AEP, DOE, BPA, and NYPA

• First commercially available PMUs made by Macrodyne (Model 1690, 16/32 channels) in the early 1990s, and installed at Western System, AEP, and NYPA.


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• Phasor: Rotating Vector. A sinusoidal signal can be represented by a cosine function with a magnitude A, frequency ω, and phase φ.

• A is the rms value of the voltage/current signal

Synchrophasor Definition

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• Polar coordinates:

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Two phasor representations

Both formats acceptable for synchrophasor data streaming

• Rectangular coordinates:

• From the synchronized measurement of the adjacent bus voltage phasors at the same time instants, the P,Q flow can be computed

• Note: The two voltage phasors have to be measured at exactly the same time

• Looking at angle separation between generator and load buses provide a reliable way to assess system stress conditions

Synchrophasor Need

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• A Phasor Measurement Unit (PMU) has been defined by the IEEE as “a device that produces Synchronized Phasor, Frequency, and Rate of Change of Frequency (ROCOF) estimates from voltage and/or current signals and a time synchronizing signal”.

• Phasor Measurement Unit (PMU) – A transducer that converts instantaneous three-phase analog signal of voltage or current into Synchrophasors.

• The synchrophasor and frequency values must meet the general definition and minimum accuracy required in the IEEE Synchrophasor Standard, C37.118-2011.

Introduction to Phasor Measurement Units (PMUs)

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Introduction to Phasor Measurement Units (PMUs): Instrumentation including a PMU

PMUs can measure the following:•Sequence voltages and currents•Phase voltages and currents•Frequency•Rate of change of frequency (ROCOF)•Circuit breaker switch status

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Introduction to Phasor Measurement Units (PMUs): Inside a PMU

• Correct operation of a PMU requires a common and accurate timing reference.

• GPS (Global Positioning System, 1973, originally 24 satellites) –32 satellites in medium Earth orbit: 2 micro-second accuracy provides accurate time signals to the GPS clock.

• IRIG-B pulses from the GPS clock is fed to the PMU for timing reference.

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Introduction to Phasor Measurement Units (PMUs): Timing Signal to a PMU

Sample the continuous voltage or current signal. The figure shows 12 points per cycle (the sampling rate is 12x60 = 720 Hz).

Use Discrete Fourier Series (DFS/DFT) method to compute the magnitude and phase of the signal (i.e., applying DFS formula).

Calculate magnitude and phase for each phase of the 3-phase quantity

Using one period of data reduces the effect of measurement noise

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Introduction to Phasor Measurement Units (PMUs): Data Sampling Inside a PMU for synchrophasor estimation

• SOC count starting at midnight 01 Jan-1970

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Introduction to Phasor Measurement Units (PMUs): Synchrophasor Data Packet Configuration

=ACCPassword: ?*****

Relay 2 Date: 06/09/2011 Time: 21:04:12.964Station A Serial Number: 1110670278Level 1

=>2ACPassword: ?****

Relay 2 Date: 06/09/2011 Time: 21:04:18.916Station A Serial Number: 1110670278Level 2

=>>SET G EPMUGlobalGlobal Enables

Synchronized Phasor Measurement (Y,N) EPMU := Y ?

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Introduction to Phasor Measurement Units (PMUs): Typical Settings of a PMU

Current and Voltage Source Selection (Y,N,1,2) ESS := Y ?

Line Current Source (IW,COMB) LINEI := IW ?Alternate Line Current Source (IX,NA) ALINEI := NA ?Breaker 1 Current Source (IW,IX,NA) BK1I := IW ?Polar. Current (IAX,IBX,ICX,NA) IPOL := NA ?Alternate Line Voltage Source (VZ,NA) ALINEV := NA ?

Synchronized Phasor Measurement Settings

Message Format (C37.118,FM) MFRMT := C37.118?Messages per Second (1,2,4,5,10,12,15,20,30,60) MRATE := 60 ?PMU Application (F = Fast Response, N = Narrow BW) PMAPP := N ?Freq. Based Phasor Compensation (Y,N) PHCOMP := Y ?Station Name (16 characters)PMSTN := "SEL421_1“

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Introduction to Phasor Measurement Units (PMUs): Typical Architecture of synchrophasor data to and from PMUs

• Ensuring accuracy of CTs and PTs, which are the source of

current and voltage signals for PMUs

• Ensuring proper GPS antenna input for timing signal to the PMU

(e.g. IRIG-B)

• Ensuring proper communications with devices within the substation

• Ensuring proper communication interface with the rest of the

system

• Ensuring proper filtering needs (“P” or “M” class PMUs) during

synchrophasor measurements, as determined by the application

requirements

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Introduction to Phasor Measurement Units (PMUs): Typical installation guidance for PMUs

• Whether there is technical value addition to system monitoring

and control with the integration of PMUs

• Whether effective physical and cyber-security arrangements can

be made at a reasonable cost

• Whether it is easy to implement and integrate PMUs of different

vendors into the communication and measurement systems (they

should be plug & play and remotely configurable)

• Whether deployment cost is going to be a minor issue for new

substations in future

• Whether there is assurance for consistent technical support with

O&M regarding communications links, and measurement data

quality once PMUs are already deployed26

Introduction to Phasor Measurement Units (PMUs): Factors determining installation of PMUs

Phasors will be deployed at the following locations by 2014:

• Major transmission interconnections and interfaces

• All 500kV and above substations and most 200 kV and above

substations

• Key generating plants (all > 500 MW) in generator switchyards, even on

some individual generators

• Major load centers

• Large wind generators, solar and storage locations

• Other locations to assure 100% observability in areas with sparse PMU

coverage

By 2019, remaining 200kV and above substations, in locations needed for

local control actions, and even on the distribution network.27

Introduction to Phasor Measurement Units (PMUs): PMU Installation Criteria (Source: NASPI)

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Introduction to Phasor Measurement Units (PMUs): Distribution of PMUs & PDCs in the US as of 2012

• IEEE C37.118.1 Covers measurements only Adds frequency & ROCOF, and dynamic operation

• IEEE C37.118.2 Preserves existing data exchange Adds needed current improvements (flags & configuration)

• IEC 61850-90-5 Joint IEEE-IEC project for synchrophasor data communication Uses standard 61850 models & processes Adds communication methods where needed

• IEEE C37.242-2013

Guidelines for installation Testing

• IEEE C37.244-2013

PDC Communication and requirements29

Introduction to Phasor Measurement Units (PMUs): Latest Synchrophasor Standards & Guidelines

Outline












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Frequency Estimation at New England by PMU & FDR

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PMU Testing:Quality of synchrophasor data of PMUs


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Frequency Estimation at Manitoba by PMU & FDR

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PMU Testing:Synchrophasor Standards for testing PMUs

• IEEE 1344-1995

• IEEE C37.118 – 2005 Measurement requirements Specified in terms of the result Error limits specified Data transmission Messaging requirements only Adapted to TCP/IP & UDP/IP

• Measurements Standard: IEEE C37.118 – 2005 Steady State Performance Compliance Criteria for “P” & “M”

type PMUs Dynamic Performance Compliance Criteria for “P” & “M” type

PMUs

• Communications Standard - IEEE C37.118.2-2011 & IEC 61850-90-5

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(1) Needs complex test bed setup

(2) Requires specially trained person

(3) Very laborious

(4) Highly time taking

(5) Very costly

The above factors do not encourage the PMU manufacturers and / orutilities to get all the PMUs tested before deployment!

There is need of an automated / semi-automated method for testingand analyzing PMUs to overcome the above mentioned shortcomings

PMU Testing:Shortcomings in the conventional method of PMU testing & analysis

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(1) Time aligns the synchrophasor data of the test PMU with the ideal PMU(2) Automatically tracks the changes in the test conditions and finds the

suitable data for test analysis(3) Analyzes performance of test PMUs under different steady state and

dynamic conditions as mentioned in the IEEE Standard forSynchrophasors C37.118.1

(4) Analyzes performance of test PMUs under different realistic conditions thatare not mentioned in the IEEE Standard

(5) Allows the user to choose required tests from the suite of testconfigurations

(6) Provides visualization of test conditions and corresponding results in theform of figures while carrying out the analysis

(7) Automatically generates a detailed printer-friendly test report for the PMUinstantly after the completion of test analysis

PMU Testing using PMU Performance Analyzer:An example of testing tool

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PMU Testing using PMU Performance Analyzer:PMU Test Suite

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PMU Testing using PMU Performance Analyzer:Testbed for PMU Testing & Analysis using PMU Performance Analyzer

Phasor Data Concentrator

(PDC)

RTDS

Test PMUAnalog Test Signals

C37.118.1 Data

C37.118.1 Data

.csv Data (Offline)

Automatically generated PMU test report

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PMU Testing using PMU Performance Analyzer:Demo of PMU Performance Analyzer

– Results & Analysis of testing a commercial PMU

Outline












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Different Applications of Synchrophasor Technology

Synchrophasor Applications

State Estimation

Real Time Stability

Monitoring

Model Validation

Adaptive Protection

Online Control

Power System

Restoration

Post-Disturbance

Analysis

Source: Novosel, 2008 41

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One Typical Application: System Voltage Stability Analysis

(1) Power systems can be pushed to their voltage stability limits due to –(a) Increasing Loads(b) Environmental limitations(c) Competition(d) Sudden Contingencies

(2) Beyond stability limit, power systems experience BLACKOUT!!(Blackouts lead to huge loss in terms of money and comfort of people!)

Voltage Stability in Power Systems:

(3) Classification of power system voltage stability analysis –(a) Based on information required:

(i) Static Analysis(ii) Dynamic Analysis

(b) Based on time & purpose of analysis:(i) Offline Analysis(ii) Online Analysis

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Research gaps identified in the different approaches for online voltagestability assessment –

(1) Shortcomings of ‘Multiple Power-flow’ based approaches –(a) Computationally burdensome

(b) Not fast enough for real time applications

(2) Shortcomings of ‘Measurement Window’ based approaches –(a) Not accurate when the system undergoes changes

(b) Following assumption may not valid during the windowing period –(i) Need the load side parameters to change, and (ii) System side to remain constant

Common Approaches for Online Static Analysis of Voltage Stability

Multiple Power-flow based Approach

Measurement Windowbased Approach

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Real Time Voltage Stability Monitoring Using RT-VSM Tool:An Example of Voltage Stability Monitoring Tool

(1) Offers 2 modes of voltage stability analysis – online & offline, andcomputes the following for the monitored system –→ “Easy-to-interpret” index for voltage stability status of the load buses.

VSAI near “0” indicates: Highly voltage stableVSAI near “1” indicates: On the verge of voltage collapse

→ Voltage angle separation of the all the connected load buses → Real and reactive power injections at all the buses

→ Real and reactive power flows in all the lines

(2) Provides a simple and yet comprehensive visualization of all key metrics inthe system to the system operators

(3) Provides multiple dynamic alarm setting features to the system operators

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Real Time Voltage Stability Monitoring Using RT-VSM Tool:Architectures for implementing the RT-VSM Tool in real power systems

Option-1

SCADA

Conventional State Estimator

RT-VSM Tool

@ Control Center

Option-2

SCADA & PMUs

Hybrid State Estimator

RT-VSM Tool

@ Control Center

Option-3

PMUs

Linear State Estimator

RT-VSM Tool

@ Control Center

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Real Time Voltage Stability Monitoring Using RT-VSM Tool:Demo of RT-VSM Tool

– Results & Analysis using RTDS, commercial PMUs and PDCs

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Questions

Documents

Synchrophasor Technology – Devices (PMUs) and Applications · PDF fileSynchrophasor Technology – Devices (PMUs) and Applications Saugata S. Biswas PhD Candidate working with Prof