Tutorial 2 PMU Application and Testing

2012 Doble Engineering Company. All Rights Reserved

PMU Application and Testing

Doble Engineering Company

Jay GosaliaNestor Casilla

Presentation Topics

What is SynchroPhasor

SynchroPhasor Purpose

PMU Applications

Testing PMU

Conclusion

10th India Doble Power Forum Conference 39

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Phasor Measurement Unit

Definition : Phasor Phasor is a vector which has magnitude and angle Corresponds to a sinusoidal waveform

Waveforms + Filter = Phasor

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Fourier filter to waveforms provides Phasor


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Definition of Synchro Phasor

IEEE C37.118 definition : A Phasor calculated from data samples using

standard time signal as a reference for the measurement

Common timing reference can be local or global May be Broadcast or direct connection Referenced to Coordinated Universal Time : UTC

Global Positioning System (GPS) satellite signal is very commonly used

Phasor and Synchro Phasor

Time aligned Phasor : Synchro Phasor GPS satellites provides time stamp Time aligning helps to analyze system events

G GZs

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IEEE C37.118 and 118-1, 118-2

IEEE PSRC working group H7 worked on Synchro Phasor standard paper in 1994

1995 : IEEE 1344 Synchro Phasor standard introduced

2005 : IEEE C37.118 replaced IEEE 1344 2011 : IEEE C37.118 split in to two standards

IEEE C37.118-1 : Measurements requirements Frequency response and dynamic response

IEEE C37.188-2 : Communication requirements New configuration messages and minor changes

Total Vector Error

Actual Phasor

Expected Phasor

Error

Ref

1% TVE .573 degrees (.01 * 360 / 2) 26.5 s (at 60 Hz)


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Protection Applications : PMU

Promising Technology for Protection PMU provides power frequency Phasors

Basis for all protections No standard : Accuracy limit for wave forms with

fault transients Different response for different PMUs Fast protection functions with 100 mSec response time

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Back up applications

Power system stability Two ended fault location algorithm System diagnostics Distributed Busbar protection Load shedding Line reclosing selectivity Wide area frequency monitoring


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Power Swing Detection

Protections settings done with known max and/or min operating conditions of power system events

Actual operation of power system events may not be optimal for the setting of the protection

PMU provides Phasors in real time Better decision can be made on load shedding

and system stability Real time Phasor value helps to fine tune State

estimation

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PMU : Power Swing

Calculate the angle difference due to disturbance Apply equal area criteria Make stability decision

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G GZs

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PMU : Power Swing

Angle between will vary due to disturbance Algorithm determines if diverging or settling Blocking or tripping decision to be made

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G GZs

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Load Shedding scheme

Special Integrity Protection Schemes (SIPS), Remedial Action Schemes (RAS), Special Protection Scheme (SPS)

Load rejection, generation control, system reconfiguration

Based on pre determined sequence of actions Wide Area Stability and Voltage Control (WACS)

uses PMU data through out the system to make decisions based on power system disturbance based on algorithm

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Distance to Fault

Single ended fault location algorithm inaccuracy Fault resistance, load flow & non homogenous system

PMU enables double ended fault location PMU data from both end of the line provides very

accurate fault location Reclose decision can be made for mixed overhead and

cable transmission line Improved line patrolling :Better productivity & Reliability Fault location algorithm is based on positive sequence

system parameters

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System Analysis : NZ System

G1 thermal power station with 400 MW generation G2 small hydro generation station 2x220 kV double circuit line PMU installed at both end Removed 200 MW power to see the response

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G1 G2

SP SP


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System Analysis : NZ System

Identical frequency response at both stations Generator control compensated frequency back to

normal Good and quick understanding of system behavior

PMU provides Time aligned data No data manipulation required : quick response

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G1 G2

SP SP

CFE Network

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Automatic Generation Shedding

CFE implemented AGSS scheme CFE has generation in southeast part of the

country while the large load is in the center If the angle between generation & load bus

exceeds certain value, generation can be tripped Loss of 400kV transmission capacity can cause

system out of step condition One line out of service : 70 Phase shift Both line out of service : 140 Phase shift

CFE chose 100 to be setting for load shedding

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CFE Network

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Local Phasor

Remote Phasor

Threshold

+-

PU Cyc

0

Trip SelectedGenerators


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Communication Channel Analysis

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Comm. Channel Analysis

Both ends Current diff. with PMU measurements Initial charging current higher then expected

Almost reached tripping threshold Load current will retract away from tripping threshold

Load increased but diff current increased towards tripping threshold

Angle difference was almost 60 Degrees Communication asymmetry higher then expected Or Phasing error

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Comm. Channel Analysis

Meter command at both end of the protection Shows same measured values Meter command uses VA source as reference

VA = 345kV 00

VB = 345kV -1200

Vc = 345kV 1200

Meter command is not sufficient If VA is connected to VB& VB is connected Vc & Vc is

connected to VA results will be same PMU solves the problem

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PMU Measurements

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PMU Measurements

PMU measurements eliminated rolled Phasor Communication asymmetry the cause for high diff Subsequent tests on comm channel indicated

high degree of asymmetry

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PMU Testing

PMU Testing Concepts Setting up a test Running a test Understanding the results


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PMU Concepts

What does a PMU report (see IEEE C37.118.2)?A stream of data messages at a given sample rate(in the range 10-60 per second)

Each message includes: One or more Phasor vectors (magnitude and angle) Frequency Deviation from nominal (Hz)

ROCOF (Hz/sec)

Phasor vectors

PMUs can report vectors for: Currents and voltages Individual phases (A, B, C) Positive sequence

All of the above Vectors can be reported as polar or Cartesian,

and as floating point or scaled integer.


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PMU Testing Concepts

Goal: under various conditions, make sure that the reported each PMU data message matches the expected values for each Phasor Vector, Frequency Deviation and ROCOF.

PMU Testing Standard

Defined in IEEE C37.118.1 Specifies quantities to vary, ranges to vary over,

and required accuracies under different conditions.

Includes steady state tests, dynamic tests, and transient tests


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IEEE C37.118.1 Requirements Steady state tests

Frequency Voltage Current Phase (discrete or continuous) Harmonic Distortion Out of band interference

Dynamic tests Phase and Amplitude Modulation Phase Modulation Linear Frequency Ramp

Transient tests (NYI in Protection Suite) Magnitude step Phase step

Setting up a test - Hardware

(PC, F6150 and PMU each have IP addresses)

Protection Suite F6150 : Waveform definitions, start timeProtection Suite PMU : Request config, start transmissionF6150 PMU : Generated waveformsPMU Protection Suite : Config response, phasor data stream


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Setting up a test - Software

Select PMU capability in Device Parameters Enter nominal voltage, current and frequency Enter VT and CT ratios Enter response time Add all IEEE C37.118 tests to the Test Plan Adjust test parameters as desired

Definitions

Pretest Time: period of time at the beginning of each test during which nominal amplitude, phase and frequency are generated

Test Time: length of each test point in the generated waveform

Response Time: initial period during each test point during which Phasor results are discarded before analysis


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Running a test

Ensure connectivity from Protection Suite to both F6150 and PMU

Test clock synchronization by calibrating Adjust Phasor order if necessary Autorun!

Understanding the Results

For each test point, maximum error over all PMU samples, excluding Response Time: TVE (Maximum error over all Phasors) Frequency error ROCOF

Pass/Fail indicator relative to tolerance Export of raw details is available


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Detailed Results

Results for individual Phasors (rather than the maximum error over all Phasors)

Average and RMS TVE% (in addition to the maximum)

Angle error (useful for troubleshooting clock issues)

Complete trace of all PMU data messages

Detailed Results Complete Trace


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Summary

With Protection Suite 2, all IEEE C37.118 tests can be set up in minutes and autorun in less than half an hour.

The final two transient tests are scheduled for implementation in release 2.1, within a few months.


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Documents

Tutorial 2 PMU Application and Testing