Open Fle Overview Public

1 © 2012 Grid Protection Alliance.

Open Fault Location Engine - BETA July 19, 2012

www.GridProtectionAlliance.org

http://www.gridprotectionalliance.org/


Development Overview

For an input file “1234.pqd”


openFLE Computational Approach

• As an extensible platform, openFLE has

two major layers:

• Get event data:

– openFLE frees developers from the chore of

reliably parsing and positioning event data for

analysis

• Perform the calculations:

– openFLE can be extended with new

algorithms


openFLE Computational Approach


Completed Items for Fully Automated System

• Data Layer

– Discover when files are dropped in a folder

– Parse COMTRADE or PQDIF files (including COMTRADE ’96)

– Reliably and predictably convert time domain data to frequency

domain for each cycle of data available

• Calculate true RMS voltage and current magnitudes

• Curve fit data to determine phase angles

• Computational Layer – A working Example Implementation

– Identify the cycles where a fault is present

– Determine fault type

– Calculate fault impedance based on the fault type

– Calculate fault distance

– Output calculations and logs

– Move input files from drop folder to results folder.


RMS Calculation and Curve Fitting Required

since Fault Data Isn’t Purely Sinusoidal


30 Values Computed for Each Cycle

• Phase VoltageN – Magnitude and Angle

• Peak Phase VoltageN

• Sequence Voltages – Pos, Neg, Zero, Magnitude

and Angle

• Phase Currents – Magnitude and Angle

• Peak Phase Current

• Sequence Currents – Pos, Neg, Zero, Magnitude

and Angle

Magnitude based on RMS calculation from individual measurements.

Angle based on phase difference to sinusoid fitted to data.


Detecting a Fault

• Assume the first cycle represents pre-fault

condition

• A fault is detected in any cycle where the RMS

current (cycle value) exceeds pre-fault current

by a factor of 5 AND exceeds 500 amps

Improvement: Use line ratings as part of the

basis for fault detection.

• Other simple methods to implement ?


Determining the Fault Type

• For each phase, the fault test was applied

• The representative best fault cycle is

selected as the one with the largest sum of

all RMS currents

• The number of currents which pass the

fault test determine the fault type.

• Other simple methods to implement?


Determining the Fault Location

• Calculated Fault Impedance using the Absolute Value

Method (Reactance method was tested and found to be less accurate.)

• 3 Phase

Select phase with “purest” sine wave

ZF = RMS (cycle data) |VN| / |I|

Distance is ratio ZF/Z1

• Line to Ground

– ZF = RMS (cycle data) |VN| / |I|

– Distance is ratio ZF/ZS (where ZS is loop impedance)

• Line to Line

– ZF = RMS (cycle data) |VL-L| / (|IP1 - IP2| )

– Distance is ratio ZF/Z1


The Test Event Files

• Event 1 – Line-to-Ground (A), DFR, 14.9 miles

• Event 2 – Line-to-Ground (A), DFR, 30.9 miles

• Event 3 – Line-to-Line (AB), DFR, 18.6 miles

• Event 4 – 3 Phase, DFR, 2.3 miles

• Event 5 – 3 Phase, DFR, 5.9 miles

• Event 6 – Line-to-Line (AB), PQM, 29.5 miles

• Event 7 – Line-to-Line (BC), DFR, 7.5 miles

• Event 8 – 3 Phase (C), DRF & PQM 36.4 miles


Data Anomalies

• Bad GPA developed configuration file –

successfully resolved through COMTRADE

configuration information

• One file with bad channel index – openFLE

gracefully ignores file.

• Sign seemed inverted on one set of data.


Seemingly out-of-phase

Measurements

A-phase Voltage

A-phase Current


Two Fault Location Methods Tested

TVA Provided Data Yielded 20 Test Cases

(All values in miles)

Absolute calculation method selected based on

better alignment with actual fault distances.

RESULTS


TVA Calculation vs. Actual Location

Actual Distance (Miles)

RESULTS

TV

A C

alc

ula

ted

Dis

tan

ce

(M

iles)


openFLE Calculation vs. Actual Location

Actual Distance (Miles)

RESULTS

op

en

FL

E C

alc

ula

ted

Dis

tan

ce

(M

iles)


Calculated Location –openFLE vs. TVA

TVA Calculated Distance (Miles)

RESULTS

op

en

FL

E C

alc

ula

ted

Dis

tan

ce

(M

iles)


CodePlex Template Established

http://openFLE.codeplex.com


openFLE Manager

Documents

Open Fle Overview Public