System for visual monitoring of operational indicators in an electric power system

A visual monitoring system for an electric power substation includes at least one camera for obtaining the image of various operational indicators in the substation, either within the control house, outdoors or both. The indicators could be the status of various gauges, including current, voltage and temperature gauges, or other structural elements, such as the position of various switches, the level of oil in a transformer sight glass, or whether a transformer fan is running, among others. The image is then enhanced to accentuate the desired features, and the desired data is then image detected. The resulting information is then compared against a standard to determine whether or not the operational status of the indicator is abnormal.

TECHNICAL FIELD 
This invention relates generally to monitoring apparatus used in electric 
power systems, and more specifically concerns image monitoring and 
analysis of operational indicators present in an electric power substation 
or similar control apparatus for electric power. 
BACKGROUND OF THE INVENTION 
When the electric power industry was first established and initial power 
distribution systems developed, human operators monitored the various 
meters and gauges used in the system. In the event of an overload or fault 
within the system, as indicated by such meters and/or gauges, the operator 
would manually trip a circuit breaker, interrupting the flow of power 
until the particular problem causing the overload and/or fault was 
corrected. 
As power systems grew and expanded, human operators were gradually replaced 
by automatic protection systems of varying sophistication. Later, 
automatic control systems were developed to control and integrate the 
operation of the automatic protection systems. 
In automatic protection systems, an apparatus generally referred to as a 
relay was developed to compare actual line voltages and currents against 
preselected standard or normal values. If the measured values were not 
within the established tolerances, the appropriate circuit breakers were 
tripped by an electrical signal. For a long time, relays were structurally 
electromechanical and, while somewhat effective, were quite 
function-specific and limited in their capability and coverage. A large 
number of such relays was necessary to provide adequate coverage and 
protection. These electromechanical relays did, however, eliminate the 
need for human operators for the specific function covered by the relay. 
This eventually led to the "unmanned" substation. However, such relays 
still included so-called "targets", i.e. visual indicators, which were 
intended for operator viewing, so that an out-of-circuit condition 
determined by the relay could be recognized by the operator by an 
inspection of the front panel of the relay, where the target lights were 
located. 
Digital relays have been a recent development in power system protection. 
Digital relays use computer (microprocessor) techniques to detect 
out-of-tolerance system conditions, and they are replacing the existing 
electromechanical relays. These microprocessor-based relays provide a 
substantial increase in coverage, flexibility and information concerning 
the particular overload or fault condition detected. In addition, 
sophisticated control systems have been developed to link such relays 
together to a central facility. 
While digital relays still retain "target" visual indicators, such visual 
information is now typically of little direct use, since the relay 
provides a large volume of printed data concerning the power system 
conditions and any overload/fault existing on the line associated with the 
relay. 
However, even the most sophisticated digital relay still uses measured 
voltage and currents from the power system line and converts those values 
to levels suitable for processing within the relay. Further, hard wire 
connections are still necessary from the relay outputs to follow-on 
devices such as switches, circuit breakers and other equipment. 
In addition, there are many system indicators present at a power system 
substation which represent the status of various devices at the substation 
and/or particular aspects of the power system which are expensive, 
inconvenient and/or difficult to communicate electrically to a relay for 
processing. These indicators include, for example, temperature and 
pressure gauge data, and the actual physical condition of various 
equipment such as transformers, circuit breakers, capacitor banks, fans, 
etc. Even for conventional current and voltage measurements, the high 
voltages and/or isolation requirements of the measuring devices add 
significantly to the expense of those devices. 
Hence, current monitoring systems using digital relays with measurement of 
actual voltage and currents on the power line actually use only a small 
number of the possible monitoring opportunities present in the typical 
substation. Even so, the trend in substation monitoring is toward faster 
and more sophisticated processing of measured voltages and currents, 
rather than making use of other system condition indicators present in the 
substation, both in the control house and outdoors. 
In the present invention, however, monitoring of the operation of a 
substation includes information obtained from a substantially wider array 
of various existing system indicators at the substation, at the same time 
taking advantage of digital processing technology. 
DISCLOSURE OF THE INVENTION 
Accordingly, the present invention is a system for visually monitoring the 
state of various operational indicators present in an electric power 
control or monitoring environment, comprising: means for obtaining an 
image of the status of a plurality of operational indicators in said 
electric power environment; means for processing that obtained image to 
enhance recognition of the status of the indicators; and means for 
comparing the processed image to a preselected standard to determine the 
state of the indicator.

BEST MODE FOR CARRYING OUT THE INVENTION 
FIG. 1 shows a very simplified, schematic view of the various major 
elements of a representative electric power substation arrangement or 
layout, which will be used for the explanation of the invention. It should 
be understood that electric power substations can vary significantly in 
their arrangements, depending upon the geographical area in which they are 
located, the parameters of the particular power system of which they are a 
part, and whether they are a "local" distribution substation or a high 
voltage transmission substation. 
Generally, however, the example substation shown at 10 will include 
three-phase high voltage lines 12 (2.4-765 kilovolts) coming into the 
substation and three-phase outgoing feeder lines at 14 (2.4-765 kilovolts) 
to the particular portion of the overall power distribution system the 
substation 10 is intended to serve. Substation 10 may include a plurality 
of voltage transformers 16--16 in the substation yard (outdoor) which will 
produce a reduction in the voltage level from the incoming high voltage 
line. Feeder line regulators 17 may also be present, along with feeder 
line circuit breakers. Further, in some applications, the yard will 
include large capacitor banks (not shown), each of which may include 100 
or more individual capacitors. Such large capacitor banks are a part of 
high voltage transmission substations. Further, the substation will 
include various switch gear, including disconnect switches 21. 
Still further, the substation may include an enclosed control center 20 
(control house) which includes a number of protective relays and a variety 
of other indicators for determining substation operation. 
In general, a substation includes sophisticated and expensive systems for 
monitoring, reducing and switching a high incoming voltage on one or more 
power lines (three phases each), as well as sophisticated monitoring and 
relay apparatus for indicating the operational status of the system, 
including specifically the monitoring of voltage and current levels on the 
feeder lines which proceed from the substation ultimately to the 
customers. 
While, as indicated above, the present invention is explained in the 
context of the substation of FIG. 1, it should be understood that the 
actual configuration and arrangement of a substation for which the present 
invention is useful may vary widely. Further, it should be understood that 
the present invention is useful in a variety of electric power generating 
situations, including power transmission and distribution systems, and 
electric power facilities such as substations, switch yards and other 
similar control facilities. 
In the present invention, various operating elements and indicators present 
in a typical substation environment (or other electric power control 
situation) are monitored by an image-capturing means, such as a camera. 
This can be done both inside of the substation control house 20 or outside 
in the substation yard. A plurality of cameras will typically be used, 
both indoor and outdoor, although it is possible that the system could 
include only a single camera, to monitor a select few indicators. The 
captured image could be in the form of a series of still photographs, or a 
slow-scan television video, or a full-speed video at 30 or more frames per 
second. The camera can be fixedly mounted or it can be mounted so as to 
scan or pan over a selected area, i.e. between selected indicators. 
While the primary embodiment described herein includes a camera which 
acquires visual images of various indicators, it should be understood that 
other sensing devices could be used, either alone or to supplement the 
visual camera images. This could include microphones to capture sound, as 
well as infrared or RF sensors to acquire infrared or RF information from 
various elements or devices. The visual information, however, is likely to 
be the most important sensing information in the system. 
Inside the control house 20, there are a number of indicators typically 
present which can be the subject of visual monitoring. As indicated above, 
all such control houses include a variety of protective relays, both 
electromechanical and digital. Only one relay is shown for illustration in 
FIG. 2; however, it should be understood that a typical control house 
might include a total of 20-100 relays, both electromechanical and 
digital, mounted in panels. These relays typically have visual operation 
indicators, in either the form of small lights or mechanical targets 
released into a viewing window by relay operations. These illuminated 
targets can be the subject of visual monitoring. In addition, there are 
various meters and gauges which are connected to appropriate elements or 
devices in the control house for readout of current, voltage, power, 
temperature and pressure values, among others. Switch positions can be 
ascertained and clocks can be monitored. In addition, the status of indoor 
circuit breakers, lamps and controls for outdoor circuit breakers can be 
monitored. 
FIG. 2 shows a few representative control house, i.e. indoor, indicators 
along with camera 40 for illustration. In a portion of one particular 
panel switchboard 46, for instance, could be located a protective relay 49 
having one or more visual indicators 51. Meter 47 could be a gauge for 
current, voltage, power, temperature or other information. Elements 48 and 
50 are indicating lamps (open, monitor, close positions) and a 
control/operating handle for an outdoor circuit breaker, respectively. The 
camera will capture the position of the handle as well as the status of 
the indicator lights. In addition to the lamp being illuminated/not 
illuminated, the lamps may have different colors when lit, which produces 
additional discrimination capability. 
The visual monitoring system of the present invention can thus take 
advantage of color changes in selected operating elements as well in 
determining status of various indicators. Element 52 in FIG. 3 is an 
indoor circuit breaker, with a handle 54 and a target light 56. The indoor 
circuit breaker 52 may also have setting plugs 58 for convenient setting 
of operational parameters. 
The above explanation relative to possible indicators which may be found in 
a substation control house 20 is intended to be representative only of the 
various indicators which could be present in the control house. Further, 
as indicated above, in addition to obtaining visual images, the present 
invention can utilize other types of sensors, including microphones. For 
instance, a microphone can be used to capture alarm signals and/or the 
particular sounds circuit breakers or other components make during 
operation. Further, IR (infrared) and RF information from various devices 
can be compared at intervals, with significant changes being an indication 
of a change in operation of a particular device. 
With respect to outdoor indicators, these could also include a variety of 
operating elements, including switches, circuit breakers, transformers and 
capacitor banks, among others. With respect to circuit breakers, the 
status of the breaker itself and its operation can be observed, as well as 
breaker contact-state indicators, operation counters and the status of the 
breaker motors. With respect to transformers, pressure, temperature and 
oil gauges could be viewed, as well as operation of particular components 
such as the transformer fans, to ensure actual operation. Tap changer 
switches can be viewed, as well as the indicators of tap position. With 
respect to capacitor banks, blown fuses can be detected as well as bulging 
capacitor cans. Mechanical deflection of bus bars in the yard can also be 
observed. 
FIG. 3 shows the use of two cameras 60 and 62 used to view an outdoor 
transformer 64. Instead of two cameras, a single camera can be used with 
mirrors in order to properly view the complete transformer. With respect 
to the transformer itself, the image monitoring system can look at the 
operation of cooling fans 66 as well as the oil levels in the sight 
glasses 68 on the individual transformer bushings 69. A drop in the oil 
level can be seen directly by the system of the present invention. At the 
present time, there is no easy way for detecting the status of the oil 
level in the sight gauges on the transformer bushings There may be other 
gauges or indicators on the transformers as well. 
Outdoor capacitor banks (not shown) can also be looked at, to determine the 
status of the capacitor fuses, as well as the physical condition of the 
capacitor cans themselves, for bulges or even ruptures. The detection of a 
single bad capacitor or one blown fuse is difficult with current systems, 
but even one bad capacitor can have a significant negative impact on the 
operation of the capacitor bank as a whole. 
FIG. 4 shows another aspect of outdoor power system substation apparatus 
which can be monitored by the present invention. High voltage switch gear 
is shown generally at 70. The scene is viewed by a camera 71. Element 72 
is a circuit switcher apparatus. The position of switch arm 74 of the 
circuit switcher can be readily determined by the visual image means of 
the present invention. Cabinet 76 contains the controls for the circuit 
switcher. Various visual elements associated with the cabinet can be 
monitored, including the position of the control handle and the presence 
or absence of security tags or locks on the cabinet. 
In addition, FIG. 4 shows a grounding switch 78 and a surge counter 80, 
which are located on a lightning arrester apparatus 82. The monitoring 
system of the present invention can read the number of surges which are 
indicated on the counter 80. 
Hence, the status of the outdoor switchgear, including the specific 
position of switch arms as well as the status of various other indicators, 
can be conveniently monitored by the system of the present invention. 
In addition to the above-described existing monitoring aspects of control 
house and outdoor (yard) indicators, other sensing devices become 
practical for use in a substation. FIG. 5 shows one such sensor, as an 
example. Referring to FIG. 5, element 86 is one contact of a disconnect 
switch, while element 88 is an LCD temperature-detecting strip 
(thermometer). The monitoring system of the present invention is capable 
of reading the temperature of the switch contact, as detected by the 
thermometer. Element 90 is a fault indicator, with a target. The 
monitoring system is also capable of reading the fault-indicating target. 
Such so-called "observational" sensors/transducers (such as temperature 
indicators) provide significant information, and are relatively 
inexpensive when observed directly, compared with transducers which 
convert temperature information into electrical signals. 
Particular sensors and/or various indicators could also be designed so that 
the visual aspects of their operation are enhanced. For instance, marks 
and/or scales can be used on switch gear or other devices to more readily 
measure deviations from a nominal position. This could be done, for 
instance, with switches to determine to what extent the switch is open or 
closed. Further, contrast detail could be added to particular parts of 
various indicators to increase their visual distinctiveness, including the 
use of distinctive colors. 
Other devices which measure a selected physical property in terms of visual 
information, such as the LCD thermometer described above, which changes 
color at different temperature points, depending upon the temperature 
exposed to the LCD, can be conveniently used with the present invention. 
Such a device could be applied to transformer banks, bus bars and other 
conductors where temperature sensing is desirable. 
Still further, bar codes or other kinds of labeling could be used to more 
specifically identify certain apparatus or indicators so as to simplify 
the connection between each indicator and its function in the overall 
protective/monitoring system. 
FIG. 6 is a block diagram showing the processing steps which take place in 
the monitoring system of the present invention. The camera 94 first 
acquires the indicator image, which is then digitized by a conventional 
digitizer 96. This digital information may be temporarily stored for 
processing or may be saved in long-term storage at 98. These initial image 
acquisition and digitizing steps are shown collectively at block 100. 
Once the image has been acquired and digitized, it is then enhanced, as 
shown at block 102. In this process, noise on the image is reduced, any 
edges in the image are sharpened, and the image contrast is enhanced. This 
enhancement process is accomplished by filtering the basic data. Various 
filters which could be used include a median filter, a contrast 
enhancement filter, or a histogram stretching or histogram equalization 
filter. 
In the next step, shown at block 108, the particular desired features in 
the enhanced image are detected, as shown at block 104. These include 
edge, corner and circle detection. A Robert operator, Sobel operator, 
Cross operator or Diamond operator (all well-known edge enhancement 
techniques) can be used for detecting edges oriented in any direction, 
while horizontal, vertical, left diagonal and right diagonal operators 
detect edges in the specified direction. A Hough transform is used for 
detecting a circle. Following this step, the features of the various 
objects in the image will have been clearly defined. 
In the next step, actual data will be extracted from the information in the 
image to identify the positions of various control elements, such as arms 
and switches. The extraction of data includes a determination of whether 
particular target lights are on or off, the position of switches and 
actual gauge and meter values. 
In the next step, shown at block 112, calculations are performed on the 
extracted data against specified thresholds. A decisional result from this 
step, providing information in a logical data coded format, concerns the 
condition of the switches, lights, etc. in the image relative to the 
standard or threshold value. In essence, this step makes an automatic 
determination as to whether any corrective action is required. 
Next, in block 114, the resulting data, in the form of messages, may be 
transmitted to a system control unit or other similar apparatus through a 
communication interface 116. Further, the data can be applied to control 
outputs, as appropriate, at 118, such as output contacts, which are then 
used in conventional fashion to open a circuit breaker or accomplish other 
selected action. The resulting data can be recorded using any one of 
various storage media. 
Further with respect to any corrective action, the control contacts can be 
used to control a robot-like apparatus at the substation which can 
accomplish certain selected corrective action, such as with circuit 
breakers, switches, or other kind of action. 
All of the above results in a more detailed, comprehensive monitoring of 
substation activity, without the need of a human operator. Any activity 
concerning particular equipment which is visual in nature can be observed. 
This can include the possibility of flashovers or arcing of components 
during switching, or the possible start of a fire due to a component, 
and/or the speed of operation of items like switches, in addition to their 
final position. With direct visual information, the use of expensive 
transducers can be eliminated and/or substantially reduced, thus reducing 
overall cost. 
Still further, when visual monitoring (including the ability to scan) is 
combined with aural monitoring and possibly RF and infrared monitoring as 
well, an effect similar to virtual reality can be accomplished for a 
particular substation for personnel at a remote site. 
Hence, a system has been described which results in comprehensive 
monitoring of an electric power substation through direct visual imaging 
of a plurality of different indicators in the substation which are 
representative of substation operation. 
Although a preferred embodiment of the invention has been disclosed herein 
for illustration, it should be understood that various changes, 
modifications and substitutions may be incorporated in such embodiment 
without departing from the spirit of the invention, which is defined by 
the claims which follow.