WO2017002020A1

WO2017002020A1 - System and method for detecting a fault in an overhead power line

Info

Publication number: WO2017002020A1
Application number: PCT/IB2016/053863
Authority: WO
Inventors: Simi VALSAN; Satheesh HARIRAM; Anitha Varghese; Mallikarjun Kande
Original assignee: Abb Schweiz Ag
Priority date: 2015-06-29
Filing date: 2016-06-29
Publication date: 2017-01-05

Abstract

A system and method for detecting a fault in an overhead power line suspended by multiple power transmission towers is disclosed. The power line has a first conductor and a second conductor, a first sensor is positioned on the first conductor along a first axis perpendicular to the first conductor, a second sensor positioned on the second conductor along a second axis perpendicular to the second conductor, the first axis and the second axis are at different pre-determined distances from a first transmission line tower. The first sensor and the second sensor are configured for measuring one or more transmission line parameters of the overhead power line to obtain measured values of the one or more transmission line parameters, where measuring includes use of a compensation factor based on transmission line characteristics of the overhead power line and the pre-determined distances, the measured values are used for fault detection.

Description

SYSTEM AND METHOD FOR DETECTING A FAULT IN AN OVERHEAD POWER

LINE

FIELD OF THE INVENTION AND USE OF INVENTION

[0001] The invention generally relates to the field of fault detection in an overhead power line using spatially distributed sensors and communication systems to accurately detect location of faults in the overhead power line.

PRIOR ART AND PROBLEM TO BE SOLVED

[0002] The overhead power line, also referred herein as "power line" is used in electrical transmission and distribution systems to transmit electrical energy over long distances. The power line consists of one or more conductors that are mechanically supported using transmission towers or poles.

[0003] The faults in the overhead power line result in power outages at the user end of power supply. The user end may include several entities such as the electrical lighting network for a city, power supply to residential, commercial, government and industrial units in a particular area.

[0004] The new age fault detection systems deploy sensors that are able to track the health of the power line and report any fault occurrences. For example, some sensors deployed as fault current indicators are installed for the power lines and show a flag or light upon detecting a fault. Some sensors provide data representative of current/voltage phase and magnitude and have abilities to communicate with the control system managing power in the power lines. In these sensor based fault detection methods, the accuracy of fault detection depends on accuracy of the sensor signal that further determines accuracy in determining the fault location. Wrong detection of fault location may lead to the fault remaining unattended, and further disturbances may result in power transmission.

[0005] Prior art sensor based fault detection systems also suffer from additional infrastructure costs that is needed for sensor communication with the remote control centers. For example, a standalone fault indicator in prior art, indicate the presence or absence of faults by means of LED / flop indicators. Some prior art standalone sensors do not have communication ability to communicate fault status to ground units and it is important that fault / no fault information be made available to the control center, the standalone sensor units may not be equipped to achieve this. Further, inspecting these fault indicators is a time consuming and man power intensive activity. The remote fault indicator systems of prior art solve some of the issues of the standalone local fault indicators, but the requirement of a ground unit for each set of sensors (one set consists of three sensors, one for each phase) to receive fault status communication from the set of sensors makes it an expensive and complex system. For power lines fault detection and communication continues to be an area of research to mitigate the challenge of time-intensive and costly interventions to correct the faults.

OBJECTS OF THE INVENTION

[0006] There continues to be a need for greater improvement in quick and accurate detection of faults on the power line, so that the subsequent steps of taking the corrective action, and restoring normal power flow can be achieved efficiently.

[0007] The invention disclosed provides a system and method for the fault detection and communication which provides accuracy in fault detection and communicates the sensor data to control center using optimized communication configurations with reduced number of ground units. The proposed infrastructure reduces the requirement for complex and expensive infrastructure, while ensuring the availability of fault / no fault information at the control center.

SUMMARY OF THE INVENTION

[0008] In one aspect, a system for detecting a fault in an overhead power line having a first conductor and a second conductor is described herein. The overhead power line is suspended by transmission towers spaced along a length of the overhead power line. The system comprises a first sensor positioned on the first conductor along a first axis that is perpendicular to the first conductor, a second sensor positioned on the second conductor along a second axis that is perpendicular to the second conductor, wherein the first axis and the second axis are spaced apart i.e. the first axis and the second axis (and thereby the first sensor and the second sensors in their respective conductors) are at a different (but known) distances with reference to a transmission line tower supporting the power line conductors. [0009] The first sensor and the second sensor are configured for measuring one or more transmission line parameters of the overhead power line to obtain measured values of the one or more transmission line parameters, where measured values provide for compensation to account overhead transmission line characteristics (overhead power line characteristics) and sensor placement distances (spatial distribution of sensors in their respective conductors). Here, the measured values are used for detecting the fault in the overhead power line.

[0010] In another aspect, the system includes intelligent sensor configurations for efficient and optimized communication of sensor measured values to the fault detection unit or a remote control center.

[0011] In yet another aspect, a method for detecting a location of fault in an overhead power line having a first conductor and a second conductor, suspended from (supported with) a plurality of transmission towers along the length of the overhead power line is provided. The steps in the method comprises configuring the first sensor and the second sensor for measuring one or more transmission line parameters of the overhead power line to obtain measured values of the one or more transmission line parameters and also a step to compensate the measured values with a compensation factor, wherein the compensation factor is determined considering the overhead power line characteristics and placement of the sensors in their respective conductors (distance between the first axis and second axis); and using the measured and compensated values of the one or more transmission line parameters for detecting the fault on the overhead power line.

DRAWINGS

[0012] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like reference numerals represent corresponding parts throughout the drawings, wherein:

[0013] FIG. 1 is a diagrammatic representation of a typical overhead power line used in power transmission and distribution;

[0014] FIG. 2 is a schematic representation of an overhead power line with first and second conductors and respective sensors positioned in accordance with an aspect of the invention; [0015] FIG. 3 is another schematic representation of an overhead power line with three conductors and respective sensors positioned in accordance with an aspect of the invention;

[0016] FIG. 4 is a schematic representation of the overhead power line of FIG. 3 with one exemplary sensor communication configuration;

[0017] FIG. 5 is another schematic representation of the overhead power line of FIG. 3 with yet another exemplary sensor communication configuration;

[0018] FIG. 6 is another schematic representation of the overhead power line of FIG. 3 with yet another exemplary sensor communication configuration; and

[0019] FIG. 7 is a diagrammatic representation of a sensor in accordance with one aspect of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0020] As used herein and in the claims, the singular forms "a", "an", and "the" include the plural reference unless the context clearly indicates otherwise.

[0021] The present invention discloses a system for detecting a fault in an overhead power line. A representation of an exemplary overhead power line is shown in FIG. 1 and referenced generally as 10. Typically the power line comprises multiple conductors 12 that carry electric current from one substation (terminal station) to another substation. The electric conductors are suspended/supported by transmission towers 14 spaced along a length of the overhead power line as shown in FIG. 1. Some exemplary implementations are shown here with two conductors for simplicity and some other power lines are shown with three conductors to explain the invention.

[0022] FIG. 2 is the exemplary implementation of the power line 20 having two conductors, the two conductors are referred as a first conductor 28 and a second conductor 34 suspended from a first transmission tower 24. A first sensor 26 is positioned on the first conductor 28, the position in the conductor is defined as centered at a point in the conductor intersecting with a first axis 30, the first axis 30 being perpendicular to the first conductor 28. A second sensor 32 is positioned on the second conductor 34 at the junction of intersection of the second conductor with a second axis 36 that is perpendicular to the second conductor 34. The first sensor and the second sensors in their respective first and second conductors are placed at different distances from the first transmission tower 24 i.e. the first axis 30 and the second axis 36 are at a different distances for example "d" (first predetermined distance), and "2d" (second predetermined distance), also referred by reference numeral 38 and 40 respectively, from a pre-designated first transmission tower 24 from the pluralities of transmission towers that are used to suspend the power line. Here, as can be seen in the figure, the first sensor and the second sensor are placed at a first predetermined distance and a second predetermined distance respectively from the first transmission tower and the values of the first determined distance and the second predetermined distance are different.

[0023] The first sensor 26 and the second sensor 32 are configured for measuring one or more transmission line parameters (e.g. instantaneous electric potential or current values) of the overhead power line. It will be important to note here that measurement involves processing and computations performed by the sensors to arrive at the measured value. Also, the measured values can include compensation carried out by the sensors as a processing/computing step in any measurement. The compensation can be carried out using a processed or predetermined compensation factor. The compensation factor can be based on transmission line characteristics of the overhead power line and/or based on position of the sensors (relative distances from each other) in the transmission line. The inclusion of such compensation factor allows for accurate measurement and thereby accurate detection of the fault location.

[0024] The invention is explained in more detail in reference to a three conductor power line 50 as shown in FIG. 3, where three sensors are deployed, a third sensor 44 is placed on a third conductor 42 at the first transmission tower 24 (i.e. distance of the sensor from the first transmission tower is said to be zero), the first sensor 26 on the first conductor 28 is shown at a distance d from the first transmission tower 24, and the second sensor 32 on the second conductor is shown at a distance 2d from the first transmission tower. It may be appreciated here, that this embodiment is similar to the embodiment of FIG. 1, with the only difference of addition of one more conductor and associated sensor. Any such adaptations are possible within the scope of the invention, that retains the essence, that the conductor- sensor relationship is determinable in the transmission line. Such determination of position of sensor in the conductor-transmission tower system can be made with a sensor's position as a reference and with the position of other sensors placed in the neighboring conductors such that the distance of each sensor from the reference transmission tower is different when compared to any other sensor.

[0025] To summarize, the system and subsequent method of the invention uses the current and voltage sample from the sensors and if the location of the sensor is away from reference transmission tower, compensation is applied to obtain correct measurements. The sensors are configured to pack the data representing the measured values, and transmit the data as per the communication configuration, which is described subsequently in more detail. The compensation on the measurement can be applied by the sensors or by a processing unit associated with a ground unit receiving the measurements.

[0026] The invention also includes efficient communication between the sensors such that the sensor measured values are quickly transmitted to a fault detection unit that may be a ground unit placed near one or more of the transmission towers, or it may be a remote control center. Such configurations for three conductor power line are shown in FIGS. 4-6. This aspect of the invention includes multiple sensors positioned on the first conductor and the second conductor (or more). Each of the multiple sensors on the first conductor is configured as the first sensor, and each of the multiple sensors on the second conductor is configured as a second sensor. For three conductor configuration as shown in the drawings, the third conductor is to be construed as another conductor with another sensor having a different predetermined distance from the reference transmission tower, compared to the distances of first sensor and second sensor from the reference transmission tower. Referring here to FIG. 4 multiple sensors are sensors 54, 60, 66, 72 on conductor 52', sensors 56, 62, 68, 74 on conductor 52", and sensors 58, 64, 70 on conductor 52".

[0027] Further, each of the multiple sensors irrespective whether it is on first conductor or second conductor or third conductor, is configured to communicate with at least one other sensor on another conductor, shown by the connector arrow 80, and at least one sensor from the multiple sensors (again irrespective of whether it is on first conductor or second conductor) is designated as a master sensor to communicate with at least a select group of sensors in the multiple sensors (again, irrespective of whether each sensor in the group is on first conductor or second conductor), and to receive the measured values from the select group of sensors. In the drawing representation of FIG. 4, sensors 60, and 72 are designated as the master sensors. [0028] Different communication configurations are possible for communication between the sensors and the master sensor, for example sensors communicate with each other and the master sensor such that the measured values from each sensor reaches the master sensor in a hopping pattern from one sensor to an adjacent sensor, till the adjacent sensor is the master sensor, as shown in FIG. 4. A fault detection unit is configured as a ground unit 76 to communicate with a designated master sensor, for example the ground unit 76 communicates with the master sensor 60 to receive the measured values of each of the sensor communicating with the master sensor. These measured values are then used to detect a location of fault in the overhead power line using the compensation factor as described herein above. The fault detection unit (ground unit 76) may be further configured to communicate to a remote control center 78, wherein subsequent actions of fault correction and power management during fault scenario are done. In one implementation, the fault detection unit is assigned to a specific transmission tower, the identity of the fault detection unit is useful in quickly determining the fault site as well. Such a communication configuration puts less stringent requirements on the self-powering requirements of sensors by use of energy harvesting from the power line, and on the number of ground units required. Each ground unit gets data from six or more different sensors, in an exemplary implementation. The range of normal sensor transmission can now effectively be as less as l/3rd of what is otherwise expected.

[0029] Other pre-defined communication configuration between the sensors are also possible, and are shown in FIG. 5 and FIG. 6 described briefly herein. FIG. 5 shows an implementation 82 wherein a master sensor 90 is designated for a group of sensors 84, 86, 88, 92, 94, and each sensor in the group, transmits its own sensor data to an adjacent sensor in the group, the adjacent sensor aggregates its own sensor data with the sensor data that has been received and transmits aggregated data to another the adjacent sensor on another conductor. The master sensor transmits the aggregated measured values thus received from its group of sensors, to the fault detection unit i.e. the ground unit 96. All of these communications are short range which requires low power.

[0030] In FIG. 6 another communication configuration 100 is shown, where the master sensors 104 and 106 have their respective group of sensors (for master sensor 104- sensors 102a, 102b, 102c, 102d and 102e form a group, and for master sensor 106, sensors 102f, 102g, 102h, and 102i form a group) that transmit sensor data to them, as in previous embodiments. Additionally, that master sensors 104 and 106 communicate with each other, where master sensor 104 transmits its group's sensor data to 106, which then transmits the data received from the master sensor 104 and its own group's data to remote control sensor 108. Other such configurations are also possible, and are included within the scope of the invention.

[0031] Spatially distributed sensors as described in the embodiments of the invention, reduce the number of ground unit to sensor ratio, therefore less number of ground units for overall infrastructure, reducing the installation, commissioning and maintenance cost. In some implementations, the ground units can be completely avoided by enabling the aggregator sensor (master sensor) to have more computing power.

[0032] Further, the communication co-ordination schemes between the sensors facilitates synchronized message exchange between sensors and ground units. Still further the communication configuration enhance communication range to communicate from sensor to sensor and sensor to ground unit and therefore enable reduction in overall infrastructure.

[0033] The invention in another aspect includes a method for detecting a location of fault in an overhead power line having a first conductor and a second conductor, suspended from a plurality of transmission towers along a length of the overhead power line, the method comprises positioning a first sensor on the first conductor along a first axis perpendicular to the first conductor, and positioning a second sensor on the second conductor along a second axis perpendicular to the second conductor, wherein the first axis and the second axis are at different pre-determined distances from a first transmission line tower from the plurality of transmission towers.

[0034] The method then includes a step for configuring the first sensor and the second sensor for measuring one or more transmission line parameters of the overhead power line to obtain measured values of the one or more transmission line parameters by including a compensation factor, wherein the compensation factor is based on transmission line characteristics of the overhead power line and the pre-determined distances.

[0035] The method then includes a step for using the measured values of the one or more transmission line parameters for detecting the fault on the overhead power line. [0036] The method described herein above further includes a way to communicate the measured values from the sensors. This method is explained in reference to an exemplary implementation with a plurality of sensors on the first conductor and the second conductor, where each of the plurality of sensors on the first conductor is configured as the first sensor, and each of the plurality of sensors on the second conductor is configured as a second sensor.

[0037] The method includes configuring each sensor to communicate with at least one other sensor from the plurality of sensors, and designating at least one sensor as a master sensor to communicate with at least a select group of sensors from the plurality of sensors. The master sensor is configured to receive the measured values from the select group of sensors; and for communicating the measured values to a fault detection unit for detecting the location of fault in the transmission line.

[0038] In another aspect, the invention includes a sensor 110 as shown in FIG. 7 for measuring one or more transmission line parameters of an overhead power line, where the sensor is located on a conductor of the overhead power line, at a pre-determined distance from a first transmission tower carrying the overhead power line. The sensor comprises a sensor processing unit 112 to obtain measured values of the one or more transmission line parameters by including a compensation factor based on transmission line characteristics of the overhead power transmission line and the pre-determined distance; and a sensor communication interface 114 to transmit the measured values. It may be noted here that the sensors described herein may be self-powered by use of battery or by using known energy harvesting methods that allow energizing of sensors directly from the power line. Further the communication configuration is done by adjusting sensor antenna patterns to optimize its own power requirements, increase range of sensing and reducing packet loss. The sensors use wireless communication configurations to communicate with each other and with the fault detection unit or with the remote control center.

[0039] The described embodiments may be implemented as a system, method, apparatus or article of manufacture using standard programming and engineering techniques related to software, firmware, hardware, or any combination thereof. The described operations for sensor data processing may be implemented as code maintained in a "computer readable non- transitory medium", where a processor may read and execute the code from the computer readable medium. A computer readable medium may comprise media such as magnetic storage medium (e.g., hard disk drives, floppy disks, tape, etc.), optical storage (CD-ROMs, DVDs, optical disks, etc.), volatile and non-volatile memory devices (e.g., EEPROMs, ROMs, PROMs, RAMs, DRAMs, SRAMs, Flash Memory, firmware, programmable logic, etc.), etc. The code implementing the described operations may further be implemented in hardware logic (e.g. an integrated circuit chip, Programmable Gate Array (PGA), Application Specific Integrated Circuit (ASIC), etc.). An "article of manufacture" is a non-transitory "article of manufacture" that comprises computer readable medium, hardware logic, or transmission signals in which code may be implemented. A device in which the code implementing the described embodiments of operations is encoded may comprise a computer readable medium or hardware logic. Of course, those skilled in the art will recognize that many modifications may be made to this configuration without departing from the scope of the present invention, and that the article of manufacture may comprise suitable information bearing medium known in the art.

[0040] A computer program code for carrying out operations or functions or logic or algorithms on tangible non-transitory memory of a computing device may be written in any combination of one or more programming languages which are either already in use or may be developed in future,

[0041] The different modules referred herein may use a data storage unit or data storage device. A computer network may be used for allowing interaction between two or more electronic devices or modules, and includes any form of inter/intra enterprise environment such as the world wide web, Local Area Network (LAN), Wide Area Network (WAN), Storage Area Network (SAN) or any form of Intranet or any specific electrical automation environment.

[0042] While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

We Claim:

1. A system for detecting a fault in an overhead power line having a plurality of sensors on a first conductor and a second conductor, the overhead power line suspended by a plurality of transmission towers spaced along a length of the overhead power line, the system comprising: a first sensor from the plurality of sensors positioned on the first conductor, a second sensor from the plurality of sensors positioned on the second conductor, wherein the first sensor and the second sensor are at a first and second pre-determined distances respectively from a first transmission line tower, wherein the first sensor and the second sensor are configured for measuring one or more electrical parameters of the overhead power line, wherein measuring comprises compensating based on transmission line characteristics of the overhead power line and the pre-determined distances, wherein each of the plurality of the sensors is configured to communicate with at least one other sensor for communicating electrical parameters to a fault detection unit for detecting the fault in the overhead line

2. The system of claim 1 wherein at least one sensor is designated as a master sensor to communicate with at least a select group of sensors from the plurality of sensors, and to receive the measured values from the select group of sensors; and a fault detection unit configured to communicate with the master sensor to receive the measured values, wherein the measured values are used to detect a location of fault in the overhead power line.

3. The system of claim 2 wherein the plurality of sensors communicate with each other and the master sensor such that the measured values from each sensor reaches the master sensor in a hopping pattern from one sensor to an adjacent sensor, till the adjacent sensor is the master sensor.

4. The system of claim 2 wherein each sensor is configured to communicate in a predefined pattern with at least one other sensor.

5. The system of claim 2 wherein the master sensor is configured to aggregate the measured values from each sensor to generate aggregated measured values and is further configured to communicate the aggregated measured values to the fault detection unit.

6. The system of claim 2 wherein the fault detection unit is a ground unit assigned for the transmission tower.

7. The system of claim 1 wherein the fault detection unit is a remote control center assigned for the transmission tower.

8. A method for detecting a location of fault in an overhead power line having a first conductor and a second conductor, suspended from a plurality of transmission towers along a length of the overhead power line, the method comprising: positioning a first sensor on the first conductor along a first axis perpendicular to the first conductor, and positioning a second sensor on the second conductor along a second axis perpendicular to the second conductor, wherein the first axis and the second axis are at a first pre-determined distance and a second predetermined distance respectively from a first transmission line tower from the plurality of transmission towers; configuring the first sensor and the second sensor for measuring one or more transmission line parameters of the overhead power line to obtain measured values of the one or more transmission line parameters by including a compensation factor, wherein the compensation factor is based on transmission line characteristics of the overhead power line and the pre-determined distances; and using the measured values of the one or more transmission line parameters for detecting the fault on the overhead power line.

9. The method of claim 8 further comprising: positioning a plurality of sensors on the first conductor and the second conductor, wherein each of the plurality of sensors on the first conductor is configured as the first sensor, and each of the plurality of sensors on the second conductor is configured as a second sensor; configuring each sensor to communicate with at least one other sensor from the plurality of sensors, and designating at least one sensor as a master sensor to communicate with at least a select group of sensors from the plurality of sensors, and to receive the measured values from the select group of sensors; and communicating the measured values from the master sensor to a fault detection unit for detecting the location of fault in the transmission line.

10. A sensor for measuring one or more transmission line parameters of an overhead power line, wherein the sensor is located on a conductor of the overhead power line, at a predetermined distance from a first transmission tower carrying the overhead power line, the sensor comprising: a sensor processing unit to obtain measured values of the one or more transmission line parameters by including a compensation based on transmission line characteristics of the overhead power transmission line and the pre-determined distance; and a sensor communication interface to transmit the measured values.