Patent Application
20210219383
The present disclosure relates to electrical powerlines in general and, more specifically, to a system and method for detecting hardware, mechanical, and electrical failures and precursors to failure in electrical transmission and distribution systems through real-time monitoring of movement changes over time.
Powerlines are a critical element of the electrical grid. The health of these powerlines can be impacted by many factors, including:
Conventional methods for detecting failures and precursors to failure involve physical inspection by humans and more recently advances in SCADA and Light Detection and Ranging (LiDAR) technologies. Due to time, resource constraints and accessibility challenges, physical inspection by humans tends only to be done on an intermittent basis; often lines are inspected less than twice a year. SCADA and LiDAR technologies, while relevant to electric system monitoring and helpful to accelerating human-led inspection, have serious shortcomings including a dependence on electrical signature for insights (SCADA), moment-in-time limitations (LiDAR), as well as a general inability to pinpoint fault/failure location with precision (SCADA). When coupled with the more extreme weather patterns resulting from climate change, this lack of real-time asset monitoring capability on the part of utility operators increases the risk that a line-level failure with an unknown location has costly and devastating ramifications either due to a wildfire outbreak or extensive storm damage.
The present disclosure describes a system and method that detects failures and precursors to failure in transmission and distribution powerlines. One indicator of asset health is a change in movement behavior of the powerline, which can be tracked via a suite of sensors including a 3-axis accelerometer, barometric pressure gauge, and line and ambient temperature gauges, installed between sets of distribution and transmission poles and towers. As will be described in greater detail, a series of sensors are positioned to monitor barometric pressure, ambient and line temperature, as well as movement and vibration on each powerline segment between poles or towers and also on some powerline poles and towers. A profile of those sensor readings is developed for each sensor, with GPS location measurements taken at install. More particularly, the sensors are all calibrated to a common standard (e.g., sea level) prior to installation. Thus, the height of the sensors relative to the poles and towers is fixed and known. By observing the fluctuation from the measurements in the sensors on the powerlines compared to other sensors on other lines in the same pole to pole segment we can determine changes in movement that indicate faults, failures or precursors to failure with location precision. Specifically, the process described herein relates to a novel technique to identify segments of the powerline that are in need of inspection and/or maintenance without requiring physical inspection. The following elements are used as part of the overall system.
Elements
Sensor Tags.
These tags comprise a collection of sensor elements that are installed on transmission and distribution lines between pole and tower segments. Those skilled in the art will appreciate that some conventional monitoring systems use electrical power induced from the powerlines and thus cannot operate when the powerlines are depowered, which in the age of utility-controlled public power shut-offs (due to wildfire) and widespread outages resulting from massive storm damage, is increasingly common. In contrast, the sensor tags described herein are powered by batteries that allow them to transmit and receive updates for over 15 years and also allow for data collection and transmission when powerlines are depowered, providing operators with readings to assess asset risk in real-time, during an emergency and throughout power restoration periods.
The sensor tags' inclusion of a 3 axis accelerometer and/or gyro sensor aids in the determination of precision changes in movement and permits the system to understand if the line is swinging or static or vibrating when the barometric pressure and temperature measurements are taken.
A transceiver provides a wireless link between the sensor tags and a backhaul communication node placed up to two miles away. In one embodiment, the transmitter is configured for operation in accordance with IEEE 802.15.4. However, other low power transceivers can be used satisfactorily with the system 100. The system 100 is not limited by the particular form of the wireless communication with the sensor tags. In yet another exemplary embodiment, the sensor tags can communicate directly with a satellite using a satellite link. This embodiment can eliminate the need for the backhaul communication node.
Over time a profile is developed based on the behavior of a particular line relative to similar lines in the system. A combination of factors including line location, line size, line current, line voltage, line tension, temperature, seasonality, wind speed and direction, and relative humidity contribute to the profile. Situational measurements are documented at or prior to install and risk thresholds are set relative to the installation specifications. That profile is sent to the individual sensor tags and is used to define the thresholds of normal movement. Once a profile is set, the sensor tags can monitor operation and report data only when an anomaly is detected. In addition, the sensor tags can report data periodically to confirm that the device is operational. Either way, the number of transmissions required by the sensor tags are greatly reduced and thus battery capacity is conserved.
Backhaul Communication Node.
The overall system includes a number of backhaul communication nodes. The backhaul communication nodes can be placed on poles or towers at intervals along the transmission and distribution pathways. The backhaul communication nodes collect information from a number of sensor tags over varied distances and transmit that data either via cellular or satellite to the cloud for monitoring by operators. These backhaul communication nodes are powered by solar panels and have a rechargeable battery. If the solar panel is damaged, the backhaul communication nodes can still receive signals from tags and transmit data for 2 weeks. The backhaul communication nodes can also report the damage to the solar panel.
Pole/Tower Tags.
These tags are sensors installed on poles or towers themselves, or on equipment sitting on the poles or towers (e.g. transformers), rather than the powerlines. The pole/tower Tags are powered by batteries that allow them to transmit updates for over 15 years and also allow for data collection and transmission when powerlines are depowered. As noted above, conventional systems that induce power from the powerlines cannot operate when the powerline is depowered. Each pole/tower Tag utilizes directional antennae to wirelessly transmit sensor data to the backhaul communication nodes placed up to two miles away, as described above with respect to sensor tags and backhaul communication nodes. The pole/tower Tags also have a 3 axis accelerometer. The accelerometer provides data necessary to understand with precision changes in movement needed to determine if the pole/tower is swinging or static or vibrating.
Patterns and Libraries.
As will be described in greater detail below, the Patterns and Libraries provide a historic operational profile used to define the normal/expected movement range and the patterns that define the changes in behavior that represent different types of anomalies.
Although
The backhaul communication node 112 collects sensor data from the sensor tags 110 that are up to two miles away via the wireless link 114. In turn, the backhaul communication node 112 relays the sensor data via various forms of wireless communication. As illustrated in
The satellite 126 relays the data to a satellite ground station 130 via a satellite ground station link 132. In turn, the satellite ground station 130 can send the collected data to a wide area network (WAN) 134, such as the Internet via a WAN link 136. Those skilled in the art will appreciate that the WAN link 136 may be implemented as a wireless link, hardwired link, optical link, or the like, or a combination thereof. The system 100 is not limited by the particular technology used to implement the WAN link 136.
Similarly, the cell tower 120 relays data from the backhaul communication node 112 to the WAN 134 via a cellular WAN link 124. As with the WAN link 136, the cellular WAN link 134 may be implemented by a combination of one or more known communications technologies. The system 100 is not limited by the specific form of the cellular WAN link 124. Although not illustrated in
The sensor tag 110 in
The sensor tag 110 of
Each sensor tag 110 is equipped with multiple sensors that provide desired sensor data. In one embodiment, the sensor tag 110 includes a barometer 152, one or more temperature sensors 154, a hygrometer 155, and an accelerometer 156. The barometer 152 for each sensor tag 110 may be calibrated at sea level so that each barometer has the same reading prior to installation on the transmissions lines 104 and distribution lines 139. Following installation, each barometer 152 will accurately measure the height above sea level. In an exemplary embodiment, the barometer 152 is a commercially available component that is accurate to within ±2 inches.
As will be described in greater detail below, the backhaul communication node 112 is also equipped with sensors, such as the barometer 152 and the temperature sensor 154 to provide reference measurements. For example, all barometers 152 are calibrated at sea level. The height of the backhaul communication node 112 is measured at the time of installation and thereby provides a reference pressure measurement. As each sensor tag 110 is installed, the pressure measurement provided by the barometer 154 in the sensor tag can be compared to the reference pressure measurement to determine the height of the sensor tag relative to the known height of the backhaul communication node 112.
One or more of the temperature sensors 154 can measure the temperature of the power transmission line 104 (see
The accelerometer 156 measures precise timing of movement of the sensor tag 110. In an exemplary embodiment, the accelerometer 156 is a 3-D accelerometer. The accelerometer 156 provides an indication of movement of the sensor tag 110 during height measurements. The danger of powerline movement is the potential for interference or asset fatigue-induced failures. For example, movement that results in greater sag could lead to phase-to-phase sparking activity; or a line could come into contact with vegetation causing an ignition; or a tree could fall into a line causing a powered line to hit the ground resulting in human electrocution. Changes in line position relative to adjacent line can be a significant problem and, when coupled with other data points, can be used by the system 100 to pinpoint fault/failure causation.
The sensor tag 110 also includes a battery 158, which has sufficient capacity to operate the sensor tag 110 for 15 years. The long battery life assures satisfactory operation without the difficult maintenance costs of frequent battery replacement.
The various components illustrated in
The pole/tower tags operate in a manner similar to the operation of the sensor tags 110 attached to powerlines. The pole/tower tags have many of the same components as the sensor tags 110, such as the CPU 140, memory 142, and transceiver 148. In addition, as noted above, the pole/tower tags also have the battery 158. The pole/tower tags also have some sensors, such as the accelerometer 156. However, the pole/tower tags may not require a full array of sensors. Those skilled in the art will appreciate that the particular sensors in the pole/tower tags are designed to elicit data regarding the performance or operational status of the pole/tower. The accelerometer 156 is used to detect movement of the pole/tower. For example, loose connections on the tower are detected by the accelerometer 156 and may indicate an imminent failure of the tower. Furthermore, in extremely high winds the accelerometer 156 may indicate that the tower is swaying in the wind. Similarly, a car could hit a distribution pole causing a live conductor to hit the ground and the accelerometer 156 would indicate immediate attention is needed.
The sensor tags 110 may also be used to monitor operating conditions in other parts of a power grid. With respect to the power transmission system illustrated in
Similarly, the sensor tags 110 may also be used to monitor operating conditions in the power distribution system illustrated in
The backhaul communication node 112 in
The backhaul communication node 112 of
The backhaul communication node 112 of
The transceiver 178 is illustrated as a generic transceiver. As illustrated in
The backhaul communication node 112 also includes a battery 182, which has sufficient capacity to operate the backhaul communication node for at least two weeks. The solar panel 113, shown in
The backhaul communication node 112 can include any or all of the sensors described above with respect to the sensor tags 110. This includes sensors, such as the barometer 152, the temperature sensor 154, hygrometer 155, and the accelerometer 156. For convenience,
The backhaul communication node 112 also includes a GPS receiver 184. The GPS receiver 184 can provide precise time and location data, including the height, of the backhaul communication node 112. However, those skilled in the art will appreciate that other satellite-based location determining technologies can be used in place of the GPS receiver 184.
The barometer 152 provides a reference pressure measurement that can be used to accurately determine the height of the sensor tags 110, at the time of installation, relative to the height of the backhaul communication node 112.
The barometer 152 and temperature sensor 154 may also provide reference data during operation of the system 100. For example, the barometer 152 on the sensor tag 110 will provide data related to changes in barometric pressure. However, the pressure changes may be due to changes in the height of the powerline, but may also be due, in part, to changes in ambient pressure as weather patterns change. The reference pressure measurement provided by the barometer 152 in the backhaul communication node 112 can be used to compensate for fluctuations in ambient pressure relative to the measurement provided by the sensor tag(s) 110.
Similarly, the temperature sensor 154 can provide a reference temperature measurement of ambient temperature away from any influence of the powerlines. As noted above, at least one temperature sensor 154 in the sensor tag 110 is configured to measure the temperature of the powerline itself. Other temperature sensors 154 in the sensor tag 110 may provide a measure of ambient temperature, but may be influenced by high temperatures in the powerline. Thus, the reference temperature measurement provided by the temperature sensor 154 in the backhaul communication node 112 can compensate for any influence of powerline temperature inadvertently measured by the ambient temperature sensor 154 in the sensor tag 110.
The various components illustrated in
A flow chart in
In decision 206, the sensor tag 110 determines whether there is profile data stored within the sensor tag. If there is no stored profile data, the result of decision 208 is NO and in step 212, the sensor tag 110 transmits the sensor data to the backhaul communication node 112 (see
In decision 210, the sensor tag 110 determines whether an anomaly is detected. This would typically be a sensor measurement that exceeds some predetermined threshold stored within the profile data. If no anomaly is detected, the result of decision 210 is NO and the process returns to step 204 to initiate another round of sensor measurements. If an anomaly is detected, the result of decision 210 is YES. In that event, the sensor tag 110 transmits the sensor data to the backhaul communication node 112 (see
Thus, the sensor tag 110 transmits all sensor data to the backhaul communication node 112 if the sensor tag does not yet have profile data. As sufficient amounts of data indicating normal operation are collected with respect to each sensor tag 110, a profile is established. Once the profile data is established, it may be transmitted, via the backhaul communication node 112 to each sensor tag and stored therein. Alternatively, the sensor tag 110 may be pre-loaded with profile data collected by the system 100 based on data generated by other sensor tags 110 under similar installation and environmental conditions. The development and use of profile data will be described in greater detail below. Once the sensor tag has profile data, it need only transmit sensor data in the event that the measurements indicate an anomaly. This approach saves battery power because it does not require transmission of data at the end of each cycle of sensor measurements.
Those skilled in the art will appreciate that variations can be readily implemented with respect to the flow chart of
In yet another alternative embodiment, the sensor tags 110 can be configured to periodically transmit data to the backhaul communication node 112. For example, the sensor tag 110 can transmit sensor data as a “heartbeat” signal every 30 minutes, or some other selected time interval, to demonstrate that the sensor tag 110 is still operational. If a particular sensor tag 110 fails to send data to the backhaul communication node 112 for a time period that exceeds the selected heartbeat time interval, the backhaul communication node can report the sensor tag 110 status as inoperative. The power company can initiate the process of replacing the faulty sensor tag 110.
In the event of a temporary outage of the wireless links 114, each of the sensor tags 110 can temporarily store all measurement data locally within the memory 142 (see
The system 100 also incorporates a degree of communication redundancy to compensate for a failure of a communication link. For example, if the backhaul communication node 112 has failed, it will not transmit the acknowledgement message to the sensor tag 110 in response to receiving sensor data. If the sensor tag 110 does not receive the acknowledgement message within a predetermined timeout period, it can be assumed that the communication link 114 between the sensor tag 110 and the backhaul communication node 112 is inoperative.
In the event of a failed communication link 114, the sensor tag 110 will transmit a link request to other nearby sensor tags 110 to establish a communication link therewith. The sensor data will be sent to one or more of the nearby sensor tags 110. In turn, the nearby sensor tags 110 will relay the sensor data to other nearby sensor tags in a form of mesh network until the sensor data is received by one of the sensor tags 110 that is in communication with one of the backhaul communication nodes 112. The system 100 is capable of relaying sensor data through multiple sensor tags 110 up and down power transmission lines 104 or power distribution lines 139 until it reaches a sensor tag that has a working communication link 114 with a backhaul communication node 112. When communications are restored with the failed backhaul communication node 112, communications can be restored to normal operation as discussed above.
Profile Data.
As described above, the Patterns and Libraries provide a historic operational profile used to define the normal/expected movement range and the patterns that define the changes in behavior that represent different types of anomalies.
Upon initial installation of the system 100 there may be no profile data in existence. Threshold data may be experientially developed based on basic knowledge of power transmission and distribution systems. Initial data thresholds can be established for temperature, barometric and accelerometer reading.
For example, a pressure change in the sensor tag 110, with respect to a reference pressure measurement in the backhaul communication node 112, indicating a height change of the powerline that exceeds one foot may be set as a threshold for reporting an abnormal condition. In addition to this pressure threshold, a selected pressure change over a selected period of time may also be selected as another pressure threshold for reporting an abnormal condition. For example, a pressure change of 0.5 millibars in a time interval of 60 seconds may be set as a threshold for reporting an abnormal condition irrespective of the ambient pressure. Thus, the system 100 can accommodate multiple different thresholds for reporting abnormal conditions. Those skilled in the art will appreciate that other pressure thresholds are also possible with the system 100.
Similarly, a powerline temperature increase of 5° F. above ambient temperature may be set as a threshold for reporting an abnormal condition. In addition to this temperature threshold, a selected temperature increase over a selected period of time may also be selected as another temperature threshold for reporting an abnormal condition. For example, a powerline temperature increase of 5° F. in a time interval of 60 seconds may be set as a threshold for reporting an abnormal condition irrespective of the ambient temperature. Thus, the system 100 can accommodate multiple different thresholds for reporting abnormal conditions. Those skilled in the art will appreciate that other temperature thresholds are also possible with the system 100.
In another example, initial thresholds for the accelerometer may be set at a force of 1G. That is, any detected force in any of the three dimensions that exceeds 1G will result in the reporting of an abnormal condition. As with the barometer 152 and temperature sensor 154, the accelerometers 156 may also have multiple thresholds.
Table 1 below provides examples of sensor measurements that correspond to abnormal powerline conditions or abnormal conditions in the transmission or distribution systems of an electrical power grid. The axis coordinate system is illustrated in
As the system 100 obtains more sensor data, it is possible to adjust the thresholds to thereby revise the operational profile in any of the sensor tags 110. In one embodiment, the system 100 uses machine learning to find normal operating ranges for the various sensors and develop new thresholds that can be individualized to each sensor tag 110. The machine learning is typically performed by the system controller 133 illustrated in
Other data generated by the sensor tags 110 may reflect normal operation. For example, it is known the powerlines always have a certain amount of sway due to the wind. The system 100 uses machine learning to determine, over time, what amount of sway is “normal” for a particular sensor tag 110. This knowledge can be used to adjust the thresholds for the barometer 152 and accelerometers 156. Similarly, the machine learning can track ambient temperature ranges as well as powerline temperature ranges over time to determine normal operational values for powerline temperature. This knowledge can be used to adjust the thresholds for the temperature sensors 154. Data from the accelerometers 156 is also analyzed as part of the machine learning process to determine powerline movements that are associated with normal activity and those that are related to abnormal operating conditions.
The machine learning uses sensor data from nearby sensor tags 110 as well as external factors (e.g., earthquakes), and environmental data (e.g., temperature, wind, precipitation, etc.) to determine whether the data from a particular sensor tag 110 is valid and whether thresholds should be adjusted up or down for any particular measurement parameter. For example, a particular sensor tag 110 may report changes in the powerline height. However, nearby sensor tags 110 may also be reporting similar movements thus indicating that wind may be causing all sensor tags to experience similar conditions that are not alarm conditions and do not require a change in thresholds. In addition, weather reports can indicate higher than normal winds that can account for the height changes.
As previously discussed, the system 100 is capable of adjusting thresholds to compensate for seasonal variations, such as hot summer vs. cold winter, rainy season vs. dry season, and the like, for any particular geographic location.
As a result of the machine learning, the system 100 can develop new threshold values to replace or supplement initial threshold values that may be programmed into the sensor tags 110 at install. As described above, the system 100 includes bidirectional communications between the backhaul communications node 112 and each of the sensor tags 110 with which it communicates. The system 100 also includes bidirectional communications between the system controller 133 and the backhaul communications node 112. As new threshold data is developed as a result of the machine learning, the system controller 133 can download the new profile data to each sensor tag 110 via the respective backhaul communications node 112.
The system 100 advantageously provides automated profile updates that are the result of machine learning. Those skilled in the art will appreciate that even sensor tags 110 that are in close geographical proximity to each other may have different profiles. For example, the sensor tags 110 on one powerline segment may be an area with dense vegetation or trees while the sensor tags 110 on the next powerline segment may be in a clear area. The same amount of movement of the powerlines may be no problem in the powerline segment in the clear area, but result in an abnormal condition in the powerline segment near vegetation or trees. The profiles developed by machine learning may be different for these different powerlines segments. Thus, the system 100 adapts to normal operating conditions throughout the power transmission and distribution systems to minimize false alarms, but detect any abnormal operating conditions.
The system 100 can store profiles for each sensor tag 110 in the system controller. These profiles can be used when a particular sensor tag 110 must be replaced. The replacement sensor tag 110 can be initially configured with the profile data from the sensor tag 110 that is being replaced. Similarly, new sensor tags 110 can be initially programmed with profile data based on similarities in the environmental conditions with existing sensor tags. For example, stored profile data can be categorized by a number of different parameters, such as installation type (transmission system vs. distribution system, line size, line tension, line temperature, operational voltage, current, and the like), region of the country (e.g., hot southern region vs. cool northern region), geologic conditions (e.g., mountains, forests, open desert, and the like), local conditions (e.g., trees, vegetation, building, and the like) and other factors known to those skilled in the art. This approach permits a new sensor tag 110 to be initially programmed with a profile whose thresholds more closely match expected operating conditions. With the machine learning process described above, the new sensor tag 110 will quickly reach a final set of threshold values individualized for that particular sensor tag.
The system controller 133 also tracks changes in the profile over time to develop a historic operational profile. Changes in the historic profile can be used to determine whether the changes are indicative of undesirable changes in the infrastructure. For example, an increase in powerline sag over a period of time may indicate weakened strength of the powerlines themselves.
The foregoing described embodiments depict different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected”, or “operably coupled”, to each other to achieve the desired functionality.
While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from this invention and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of this invention. Furthermore, it is to be understood that the invention is solely defined by the appended claims. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations).
Accordingly, the invention is not limited except as by the appended claims.
| Number | Date | Country | |
|---|---|---|---|
| 62960600 | Jan 2020 | US |
