High impedance fault detection

17 Pages·2013·1.29 MB·English

US 20050171647A1
(19) United States
(12) Patent Application Publication (10) Pub. No.: US 2005/0171647 A1
Kunsman et al. (43) Pub. Date: Aug. 4, 2005
(54) HIGH IMPEDANCE FAULT DETECTION (52) US. Cl. ............................................................ .. 700/293
(75) Inventors: Steven A. Kunsman, Allentown, PA
(57) ABSTRACT
(US); Ismail I. Jouny, Easton, PA
(US); Stephen Kaprielian, Worcester,
An apparatus, system, and method for detecting high imped
MA (US)
ance faults in electrical poWer lines using a composite high
impedance fault detection system having a voter logic that
Correspondence Address:
samples the logical outputs from a plurality of independent
ABB Inc.
high impedance detection systems and determines a high
Legal Department - 4U6
impedance fault if any tWo of the plurality of independent
29801 Euclid Avenue
high impedance detection systems indicates a high imped
Wickli?'e, OH 44092-2530 (US)
ance fault. Preferably, the plurality of high impedance
detection systems include a Wavelet based high impedance
(73) Assignee: ABB Inc.
fault detection system having a ?rst logical output, a higher
(21) Appl. No.: 10/770,270 order statistics based high impedance fault detection system
having a second logical output, and a neural net based high
(22) Filed: Feb. 2, 2004 impedance fault detection system having a third logical
output. Preferably, each of the plurality of high impedance
Publication Classi?cation fault detection systems includes an independent high imped
ance fault detection application that independently detects a
(51) Int. Cl.7 ................................................... .. G01R 31/08 high impedance fault on the electrical poWer line.
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Relay with high impedance
Detection svstem
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Patent Application Publication Aug. 4, 2005 Sheet 1 0f 7 US 2005/0171647 A1
. ./‘O——|——l—
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/ Relay with high impedance
Detection svstem
Figure #1: Electrical power distribution network having a composite high impedance fault detection system
Patent Application Publication Aug. 4, 2005 Sheet 2 0f 7 US 2005/0171647 A1
/29
Acquisition
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Data Filtering '
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Figure #2: Block diagram of a composite high impedance fault detection system
Patent Application Publication Aug. 4, 2005 Sheet 3 0f 7 US 2005/0171647 A1
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Patent Application Publication Aug. 4, 2005 Sheet 4 0f 7 US 2005/0171647 A1
Patent Application Publication Aug. 4, 2005 Sheet 5 0f 7 US 2005/0171647 A1
Data Acquisition -~ 5 O
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Data Filtering 1"
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Wavelet /—
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Calculation
Comparison (_ 6 Q
with Threshold
Detection decision
Figure #4: Flowchart showing a wavelet based high impedance fault detection system
Patent Application Publication Aug. 4, 2005 Sheet 6 0f 7 US 2005/0171647 A1
Data Acquisition "'50
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Data Filtering
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Energy r60
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Detection decision
Figure # 5: Flowchart showing a 2"‘ order statistic based high impedance fault detection system
Patent Application Publication Aug. 4, 2005 Sheet 7 of 7 US 2005/0171647 A1
Data Acquisition ” 5 O
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Figure #6: Flowchart showing a neural network based high impedance fault detection system
US 2005/0171647 A1 Aug. 4, 2005
HIGH IMPEDANCE FAULT DETECTION on PoWer Delivery, Vol. 3, No. 4, pp. 1493-1500, October
1988. This conventional arcing fault detection technique
1. FIELD OF THE INVENTION examined loW frequency currents, namely 180 and 210 HZ,
to determine Whether an arcing fault had occurred. A hier
[0001] The present invention relates in general to fault
archical detection scheme Was developed that is based on
detection in electrical power systems, and particularly, to
signature energy and using a dynamic threshold. Although
high impedance fault detection in electrical poWer distribu
the algorithm Was ?eld tested, its performance limited its
tion lines.
practical applicability.
2. DESCRIPTION OF THE PRIOR ART [0008] US. Pat. No. 4,466,071 entitled “High Impedance
Fault Detection Apparatus and Method” describes a conven
[0002] High impedance faults are characterized by a high
tional high impedance fault detection technique that moni
impedance at the point of fault. Accordingly, a high imped
tors and evaluates the high frequency components of each
ance fault typically produces a small fault current level.
cycle of an alternating current. The occurrence of a high
High impedance faults can, therefore, be generally de?ned
impedance fault is determined based on a signi?cant
as those faults that do not draW suf?cient fault current to be
increase in magnitude of the high frequency components for
recogniZed and cleared by conventional overcurrent devices,
a prescribed period of time and of a prescribed pattern.
such as protective relays.
HoWever, this patent only considers a very speci?c feature
[0003] High impedance faults result When an energiZed of high impedance fault currents and does not consider high
primary conductor comes in contact With a quasi-insulating impedance fault currents in a multi-resolution frameWork.
object, such as a tree, a structure or equipment, a pole US. Pat. No. 5,512,832 entitled “Energy Analysis Fault
crossarm, or falls to the ground. Typically, a high impedance Detection System” describes a conventional detection tech
fault exhibits arcing and ?ashing at the point of contact. The nique that compares energy values of load currents to preset
signi?cance of these hard to detect faults is that they thresholds in order to detect an arcing fault on a poWer line.
represent a serious public safety haZard as Well as a risk of HoWever, this patent is very basic in its nature and does not
arcing ignition of ?res. As such, high impedance fault consider or use other features of load currents to detect a
detection has been a major concern of protective relaying for fault.
a long time.
[0009] Another HIF detection scheme devised a neural
[0004] Protective relays are usually designed to protect netWork detection system that is trained to identify HIF
equipment (line, transformer, etc.) from damage by isolating
faults and is described in S. Ebron, D. Lubkeman, an M.
the equipment during high current conditions. High imped White, “A neural netWork approach to the detection of
ance faults, are typically found on distribution circuits, incipient faults on poWer distribution feeders”, IEEE Trans
results in very little, if any, current. High impedance faults actions on PoWer Delivery, Vol. 5, No. 2, pp. 905-914, April
do not pose a threat to equipment and by their nature they 1990. Although this study Was conducted in the early days
can not be detected With conventional overcurrent devices. of neural netWork development it did highlight the potential
Nonetheless, the dangers of a doWned conductor are obvious of adaptive learning systems in HIF detection. That pilot
to all. Possibility of ?re, property damage, and someone study did not involve any experimentally generated data but
coming into contact With the live conductor are some of the Was developed and tested using simulated HIF data gener
major concerns. ated using electromagnetic transients program (EMTP) soft
[0005] Also, legal issues in promising a comprehensive Ware. Furthermore, the neural netWork used in that study had
solution may be very costly for manufacturers (e.g., liability a relatively simple architecture.
issues). For example, tripping the breaker folloWing high
[0010] US. Pat. No. 5,537,327 entitled “Method and
impedance fault detection is not a clear cut choice. While the Apparatus For Detecting High-Impedance Faults In Electri
high impedance fault is a danger, tripping the feeder unnec
cal PoWer Systems” describes a conventional high imped
essarily Will create neW haZards by de-energiZing homes,
ance fault detection technique that uses a neural netWork to
traf?c signals, of?ces, etc. The effects of incorrectly deter
detect high impedance faults. HoWever, the features used by
mining a high impedance fault Will have economic and legal
US. Pat. No. 5,537,327, rely on derivatives of the maxima
rami?cations.
and minima of the load current. Also, Zero crossings are used
[0006] The utility must alWays have the safety of the to detect a fault. The results of long term HIF detection tests
public as a top priority. HoWever, high impedance fault conducted With the collaboration of ?ve utilities and includ
detection has not been possible in the past and realistic ing staged faults, naturally occurring faults, and normal
detection algorithms are not anticipated that can detect system operation Were published by B. Russell and C.
100% of all doWned conductors, While having 100% secu Benner, in “Arcing fault detection for distribution feeders:
rity against misoperation. The utilities need an economic security assessment in long term ?eld trials”, IEEE Trans
solution and a system that can reliably detect high imped actions on PoWer Delivery, Vol. 10, No. 2, pp. 676-683,
ance faults and are also secure in that they do not falsely April 1995. That study described in great detail some of the
detect a HIF. practical aspects of HIF detection, but it does shoW that a
75% HIF detection Was the best achievable performance
[0007] Some of the earliest HIF detection schemes using their randomness based algorithm.
involved arcing fault detection techniques that used loW
frequency current components and are described in B. [0011] British Columbia Hydro and PoWertech Labs Inc.
Russell, K. Mehta, R. Chinchali, “An arcing fault detection tested three HIF detection systems including that of Russell
technique using loW frequency current components perfor et al. described directly above (see, V. BucholZ, M. Nagpol,
mance evaluation using recorded data”, IEEE Transactions J. Nielson, B. Parsi, and W. Zarecki, “High impedance fault
US 2005/0171647 A1 Aug. 4, 2005
detection device tester”, IEEE transactions on Power Deliv the Rural Electr. PoWer Committee of the IEEE Ind.
ery, Vol. 11, No. 1, pp. 184-190, January 1996). The most Applications Soc. IEEE, a publication of a paper
signi?cant result Was that the higher frequencies of HIF given at the Rural Electric PoWer Conference held on
signatures played an important role in HIF detection and in 28-30 Apr. 1996 in Forth Worth, TeX. Which focuses
distinguishing HIF from other types of faults or normal on having multiple detection algorithms to success
arcing operations. fully balance fault detection With fault discrimina
tion. The paper does describe the Energy and Ran
[0012] In another HIF detection study, the results of years
domness algorithms of the DFM, as Well as the Arc
of experience With HIF detection and testing are summa
Con?dence Level Generator and EXpert Load Pat
riZed and the formal evaluation of the performance of a
tern AnalyZer, but does not go into great detail
randomness based HIF detection algorithm are disclosed.
regarding this implementation. The paper basically
(see, C. Benner and B. Russell, “Practical high impedance
states that having multiple algorithms (as With the
fault detection on distribution feeders”, IEEE Transactions
DFM) enhance detection of these types of faults. The
on PoWer Delivery, Vol. 33, No. 3, pp. 635-640, May/June
paper goes on to say that commercial development
1997). Despite its simplicity, and its ad hoc nature, this
has occurred With GE. Even though this paper does
algorithm does deliver relatively reliable HIF detection. This
support multiple algorithm detection it does not
technique Was implemented in a relay sold by General
challenge any of the speci?c algorithms used in the
Electric knoWn as the Digital Feeder Monitor (DFM) and
present invention.
uses nine algorithms based mainly on energy, randomness,
interharmonics, etc. in layers as shoWn in FIG. 4 on page 8 [0017] d. LaZkano, A.; RuiZ, J .; Aramendi, E.; Letu
by R. Patterson, W. Tyska, B. Don Russell and B. Michael riondo, L. A., Proceedings of Ninth International
Aucoin, “A Microprocessor-Based Digital Feeder Monitor Conference on Harmonics and Quality of PoWer,
With High-Impedance Fault Detection”, presented to the Vol. 3, pp. 1005-1010, 2000, “A NeW Approach to
Forty-Seventh Annual Conference for Protective Relay High Impedance Fault Detection Using Wavelet
Engineers, TeXas A&M University, College Station, TeX., Packet Analysis”, a publication of the paper given at
Mar. 21-23, 1994. In contrast the technique of the present the conference Which Was held in Orlando, Fla.
invention as described in the preferred embodiment uses Which presents an HIF detection technique related to
only three algorithms based on neural netWorks, statistics Wavelet packet analysis. It seems to be similar to the
and Wavelets and has a voting scheme that determines the Wavelet algorithm implemented in the present inven
detection of the HIF fault based on each of the algorithms tion as it uses the Daubechiesi4 mother Wavelet
independently detecting a HIF condition. With 4-level decomposition of the arc current signal.
HoWever, it analyZes only the 2nd harmonic value of
[0013] Other publications that describe HIF fault detection
the current. The Wavelet algorithm of the present
studies and techniques are:
invention analyZes current components in the 320
[0014] a. Snider, L. A.; Yuen, Y. S., International 400 HZ region. Thus, the theory and implementations
Conference on PoWer Systems Transients 1999, PP.
are different and the paper only describes theoretical
235-40, a publication of a paper given at the con
results.
ference held 20-24 Jun. 1999 in Budapest, Hungary,
Which presents an arti?cial neural netWork (ANN) [0018] e. Al-Dabbagh, M.; Al-Dabbagh, L.,
based relay algorithm that uses Fourier analysis to IJCNN’99. International Joint Conference on Neural
determine loW order harmonic vectors Which Were NetWorks. Proceedings, Vol. 5, pp. 3386-90, 2000,
then fed to a perceptron or feed-forWard neural “Neural NetWorks Based Algorithm for Detecting
netWork. The netWorks Were trained by feeding them High Impedance Faults on PoWer Distribution
With input vectors consisting of magnitudes or phase Lines”, a publication of the paper given at the
angles of loW order harmonics. The present inven conference Which Was held Jul. 10-16, 1999 in
tion uses a neural netWork algorithm Which is dif Washington, DC. Which describes a neural netWork
ferent as it is a multiple-layer perceptron that uses detection algorithm that is very similar to the neural
the Waveform samples as an input, not the discrete netWork detection algorithm of the present invention.
Fourier transform (DFT) or fast Fourier transform HoWever, there is a signi?cant difference betWeen
(FFT) of the loW order harmonics. the tWo algorithms. The algorithm in this paper is
also a multi-layer netWork With back-propagation,
[0015] b. Don Russell, B.; Benner, Carl L., Electric
but this algorithm uses the DFT of the current and
PoWer Systems Research v 31 n 2 November 1994.
voltage signals as inputs, instead of the individual
p 71-77, Which presents an intelligent analysis sys
tem that processes the outputs from several algo samples themselves. This paper does not indicate the
number of inputs, outputs, and hidden layers asso
rithms to determine the con?dence that a fault eXists.
This is basically What is implemented in the GE ciated With the netWork, and tests the algorithm
using EMTP/ATP simulations.
Digital Feeder Monitor (DFM). This system pro
cesses the odd, even, and non-harmonics, and uses [0019] As can be appreciated, conventional means for
the Energy and Randomness algorithms for the arc detecting high impedance faults in electrical poWer lines are
detection analysis. The system uses the Arc Con? typically not alWays conclusive and/or reliable and can be
dence Level Generator to generate the con?dence eXpensive. Therefore, a need eXists for a neW reliable and
level and the Expert Load Pattern AnalyZer for economic solution for detecting high impedance faults in
arcing persistence.
electrical poWer lines Which addresses the engineering and
[0016] c. Benner, C. L.; Russell, D., Rural Electric legal rami?cations of detecting and determining What to do
PoWer Conference 1996 PP. B2/38-43 sponsored by once a high impedance fault is detected.