VIsIOn FAuLT FInDER Automatic location of faults

vision fault finder
Automatic location of faults
in MV cable networks
Vision Fault Finder is an application that identifies the fault location using the measured voltages and currents wave forms
of a fault. The application can pin point two and three phase
faults within 100 meters. Single phase faults in earthed networks can be located with an accuracy of 500 meters.
Introduction
Most of the outage time for power
systems is caused by faults in the MV
network. The usual way of manually finding the fault location by checking short
circuit indicators is time consuming.
Utilities want to improve the network
performance and one of their goals is to
decrease the time to locate the faults.
Together with grid operator Alliander
Phase to Phase developed a fault location system.
Fault analysis
The developed fault location system
uses the sinusoidal measurement of
currents and voltages during the fault
that is provided by the substation digital
vision power range / vision fault finder
Charles Augustin de Coulomb
(1736-1806)
protection system. Then the measured
signals are processed.
In the second stage short circuit calculations are performed on a model of the
network. The results of these calculations are compared with the results of
the first stage, in order to find a location
giving the same fault impedance.
‘Artist impression’ in Vision Grid Navigator
of a fault in MV cable network
phase to phase
vision fault finder
From raw data in substation
to fault location in control centre in 4 steps
Step 1 Communication
Following an interruption in an MV cable
network, all recorded voltage and current measurements are uploaded to the
control centre from the substation. This
recording also includes pre- and postfault data.
The Vision Fault Finder application, installed at the control centre, is triggered
and starts processing the received data.
1
Measured currents and voltages
during a fault
Step 2 Signal processing and Analysis
A Fourier transform (FFT) and symmetrical components transform are carried
out to determine the absolute voltages
and currents as functions of time. The
signals are analysed and it is decided
whether this is a real fault or other event.
In case of a real fault the calculation moment for the impedance is chosen such
that most of the transients have disappeared.
The expert system applies fuzzy logic
rules to identify the type of fault involved
and the fault impedance.
The results are automatically passed to
the Vision Network Analysis application.
2
vision power range / vision fault finder
FFT transformation and determined
calculation moment
Step 3 Simulation
Vision Network Analysis selects the
correct network model and performs a
number of short circuit analyses corresponding to the found fault type. The
pre-fault values for the load and switches
are used to adjust the network model.
For all short circuit calculations the
simulated reactances, as ‘seen’ from
the substation into the direction of the
feeder, are calculated.
After this it should be possible to match
the measured reactance with the simulated reactances.
3
Simulated short circuit impedances
in a cable section
phase to phase
Step 4 Visualisation
Once the location has been calculated,
the results will be presented to the
operator graphically. The location will
be visible in both the schematic and
geographic network view. Also a report
with all the details of the fault is sent to
the printer.
With all this information the short circuits will be located efficiently. Finally the
supply can be restored by rerouting the
distribution feeders.
4
Schematic visualisation in
Vision Network Analysis
vision power range / vision fault finder
Geographic visualisation in
Vision Grid Navigator
phase to phase
vision fault finder
Overview
• Accuracy: two and three
phase faults within 100
meters. Single phase faults
in earthed networks 500
meters.
• Processing time less than
20 seconds.
• Compatible with Comtrade
format.
• Read Digital Fault Recorder
(DFR) files directly from a
SASensor™ webserver.
• Fast Fourier algorithm
implementation for signal
processing.
• Fuzzy Logic expert rules to
determine the fault type.
• The algorithm is able to
distinguish between a real
fault and other events.
• Automatic archiving on hard
disk of fault analysis results.
• Automatic generation and
printing of a report after a
fault analysis.
• User configurable colors of
charts.
• Configuration of substation
locations with DFR.
• Zooming and panning of
charts.
• Export results to ASCII or
Microsoft Excel files.
Vision Fault Finder application
Phase to Phase
The fulfilment of this vision is supported by the
Phase to Phase BV
Phase to Phase focuses on software development
growing sense of cost in planning, development
Utrechtseweg 310, 6812 ar Arnhem
for transmission and distribution network analy-
and management of the electrical infrastructure.
Postbus 100, 6800 ac Arnhem,
sis. The vision is to introduce and enhance the
The products are used by electricity companies,
The Netherlands
network analysis for a broad range of engineers
industry and consultants for network develop-
t: +31(0)26 352 37 00
by means of innovative products.
ment and analysis.
info@phasetophase.nl
vision power range / vision fault finder
www.phasetophase.nl
phase to phase