Real-Time Monitoring and Assessment of Circuit Breaker Operations For Diagnostics and Control Applications
Real-Time Monitoring and Assessment of Circuit Breaker Operations For Diagnostics and Control Applications
Real-Time Monitoring and Assessment of Circuit Breaker Operations For Diagnostics and Control Applications
Article Received: 24 February 2017 Article Accepted: 09 March 2017 Article Published: 11 March 2017
ABSTRACT
Circuit breakers (CBs) are very important elements in the power system. They are used to switch other equipment in and out of service. Circuit
breakers need to be reliable since their incorrect operation can cause major issues with power system protection and control. Today’s practice in
monitoring circuit breaker operation and status in real time is reduced to the use of Remote Terminal Units (RTUs) of Supervisory Control and Data
Acquisition (SCADA) system to assess CB status. More detailed information about the control circuit performance may be obtained by CB test
equipment typically used for maintenance diagnostics. This paper addresses two important issues: a) how improved CB monitoring may be
implemented in real-time, and b) what would be the benefits of such an implementation. The results reported in this paper are coming from two
research projects, conducted using funding from Center Point Energy and DOE-CERTS aimed at development of software for automated analysis of
CB data and the other covering development of the CB data acquisition unit respectively. The paper is devoted to description of a prototype
implementation of a real-time CB monitoring system. The system consists of a new CB monitoring data acquisition IED that is located at circuit
breaker and captures detailed information about its operation in real-time. The CB files are transferred to the concentrator PC where the application
software performs automated analysis and makes an assessment about the operational status of the breaker. The software is based on signal
processing and expert system processing. Application example using actual field data is discussed the paper ends with some conclusions,
acknowledgments and a list of references.
Close Trip
Initiate Initiate
Control
52X/a DC +
52a
52Y/b 52 Y
52Y/b
TC
CC 52 X 52a 52Y/a
Control
Fig.1.CBMA system architecture DC _
Fig.1. Control circuit of Circuit Breaker
When breaker operates, recorded files are wirelessly
transmitted to the concentrator PC. The client application From the circuit breaker control circuit shown in Figure 1.
automatically performs the analysis of recorded signals from The signals are generated during either tripping or closing of
the circuit breaker control circuit. For more efficient data the breaker. Of these 15 signals, 11 are analog and 4 are status
manipulation, IEEE file naming convention is used for signals. The monitored signals are listed in Table 1.
naming the recordings files 0. The signal-processing module
of the analysis software extracts various parameters from Table 1. Signals of Circuit Breaker Control Circuit monitored
recorded signal samples and expert system evaluates them by CBMA
against empirically obtained values and tolerances selected
for specific type of circuit breaker. Group Signal name
Trip Initiate
The resulting report describes detected abnormalities and Close Initiate
possible causes of the problem. If discovered problem Digital signals
X Coil signal
presents serious threat to the reliability of future circuit
Y Coil signal
breaker operation, programmable notification is sent to the
server located in the central office. The notification is then “A” Contact
Contacts
processed and a warning is sent via email or pager to the “B” Contact
maintenance and protection personal. Reporting is provided Control DC Voltage
for both local and geographically dislocated users through DC Voltages Yard DC Voltage
implementation of local database and web server supporting Light Wire
information exchange through dynamic HTML pages. Trip Coil (TC) Current 1
Coil Currents Trip Coil (TC) Current 2
Recorded files and reports can be downloaded to the server Closing Coil (CC) Current
via Ethernet network relying on standard, fast and reliable Phase Current A
TCP/IP protocol. In the central office or control center, the Phase Currents Phase Current B
server part of CBMA consisting of the analysis module, a Phase Current C
central database and master web server is running. The central
database allows for easy archiving and retrieving of the The most important signals are Trip Initiate and Close
records and analysis reports from all system substations. Initiate. These signals, initiated by the relay or the operator,
Master web application allows remote users to search for the cause generation of some other signals, as a result of the
records and/or analysis reports from anywhere on the circuit breaker tripping or closing. All of the monitored
corporate network (intranet). signals are voltage signals. The signals representing currents
are taken from shunts, thus converting them to appropriate
2.1 Description of CBMA Hardware voltage signals. In the worst-case scenario time between the
The system hardware in substation consists of circuit breaker fault occurrence and the breaker lockout is about 1 (one)
monitors located on each breaker in the switchyard and a minute. The monitoring device is designed to record and store
concentrator PC, used for gathering data, placed in the control recorded data for this duration.
room.
2.3 Concentrator
The concentrator device consists of a high capacity wireless
receiver connected to a PC which stores and processes data.
The concentrator can be set in one of the two modes using the
Fig.5. Waveforms of signals from CB control circuit for open
software.
and close operations respectively
Continuous monitoring: In this mode the concentrator
The signal processing consists of several steps, performed
continuously receives recorded data from each IED
using advanced signal processing techniques. Fourier analysis
simultaneously. The transmission bandwidth required for this
is used for obtaining the information on frequency spectrum
application is quite high, n x 1.4 Mbps, where n is the number
of the signal.
of circuit breaker monitors in the system.
For elimination of measurement noise, removal and
Event monitoring: In this mode the concentrator
extraction of unnecessary signal components of the frequency
continuously polls the IEDs for their status and if any trip or
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Asian Journal of Applied Science and Technology (AJAST) Page | 106
Volume 1, Issue 2, Pages 103-107, March 2017
spectrum, digital filtering is being used. Wavelet composition information given in the facts. The rules were designed to
and reconstruction algorithm is used for de-noising and enable the inference engine to perform two layers of analysis
separation of signal features. on the given data.
Only one phase current is shown because one abnormal phase REFERENCES
is sufficient to detect and classify the problem. The other [1] M. Kezunovic, Z. Ren, G. Latisko, D. R. Sevcik, S. Lucey,
phase currents may be normal or abnormal. W.E. Cook, E.A. Koch, “Automated Monitoring and Analysis
of Circuit Breaker Operation”, IEEE Transactions on Power
Delivery, [accepted for press].