Detecting Synchrophasors Computed Over Fault/Switching Transients

Dr. Sarasij Das

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This Presentation is based on the paper

Sarasij Das, and Tarlochan Sidhu, "Detecting Synchrophasors

Computed Over Fault/Switching Transients", IET Generation,

Transmission & Distribution,

http://digital-library.theiet.org/content/journals/10.1049/iet-gtd.2013.0493

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Brief overview of Wide Area Measurement

Systems (WAMS)

Proposed algorithm

Conclusions

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Voltage/current waveforms sinusoid in nature

Phasor = representation of sinusoid in complex

plane

Phasors estimated by measuring

- magnitudes

- phase angles

Traditional SCADA monitoring slow

One complete SCADA polling may take 2-10 s

Measurements are not time synchronized

Phase angle measurement no possible

Not suitable for system dynamics monitoring

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WAMS = PMU based monitoring systems

Synchrophasor = phasor + GPS time tagging

Synchrophasor = magnitude & phase angles

Synchrophasors used in system dynamics

monitoring

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Control Center

Voltage, Current Synchrophasors

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IEEE standard C37.118.1-2011[2] specifies

accuracy requirements for synchrophasors

IEEE standard C37.118.2-2011[3] specifies

message formats for communication data packets

IEEE standard C37.244-2013 [4] describes functional requirements for PDCs

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Context Synchrophasor validations mostly happen in

PDCs

Validation often offline and time consuming

Lack of samples makes validation difficult in PDCs

Lack of algorithms to compute synchrophasor quality at PMU

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Motivation

Fault/switching transient synchrophasors

computed over pre and post fault/switching

samples

Unusable in applications

Not easy to detect from values

1( ) 89.998

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1.0045( 1) 90.1340

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X k

X k

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Motivation

No existing Algorithm

However, Algorithms [1][5] can be used

Existing Algorithms [1][5] make wrong detections in

presence of harmonics, decaying dc

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Proposed low complexity algorithm to detect

fault/switching transient synchrophasor

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Suggested to apply on current signals

Success Rate

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X=Xm [1+ksx u(t-ts)]cos(ωot +ksa u(t-ts))

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Performance

during

Oscillations

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Performance

in presence of

missing samples

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Proposed algorithm performs satisfactorily

- during nominal and off-nominal frequencies

- in presence of harmonics, decaying DC

- in presence of oscillations, ramping

- in presence of a number of missing samples

- for estimation windows 2.5 cycles or

greaterPlease see the paper for additional results

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Algorithm has been proposed to tag fault/switching

transient synchrophasors

Proposed algorithm performs satisfactorily in various

scenarios

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1. “Synchronized phasor measurements and their applications”, by Arun G. Phadke, John Samuel Thorp

2. “IEEE Standard for Synchrophasor Measurements for Power Systems”, IEEE C37.118.1-2011, (Revision of IEEE Std. C37.118-2005)

3. “IEEE Standard for Synchrophasor Data Transfer for Power Systems”, IEEE C37.118.2-2011

4. “IEEE Guide for Phasor Data Concentrator Requirements for Power System Protection, Control, and Monitoring”, IEEE Std C37.244-2013

5. Sodhi, Ranjana, S. C. Srivastava, and S. N. Singh. "A transient monitor to reflect the quality of synchrophasors." Power and Energy Society General Meeting, 2010 IEEE. IEEE, 2010.

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