System and method for operating an overhead power line

Abstract

A method and system for operating an overhead electric line, the system comprising one or more distributed sensors associated with the overhead electric cable and one or more non-distributed sensors associated with the overhead electric cable, the non-distributed sensors being able to corroborate line condition values ​​obtained from the distributed sensors and also being able to calibrate values ​​obtained from the non-distributed sensors.

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure relates to the field of overhead electric power lines, and more particularly to systems and methods for operating overhead electric power lines. [Background technology]

[0002] Electric lines, e.g., overhead transmission lines and overhead distribution lines, transport electricity from point to point within the electrical grid. For example, high voltage transmission lines are used to transport electricity from generating stations to substations, and transformers reduce the voltage so that the electricity can be safely delivered to end users, e.g., using subtransmission or distribution lines that transport electricity at a lower voltage than the transmission lines.

[0003] Operators of the electric grid, including overhead transmission and distribution lines, desire to operate the electric grid as efficiently as possible, for example, by reducing transmission losses and operating the electric grid in a manner that minimizes damage to the electric lines that may occur due to, for example, overheating (which may cause the lines to sag to dangerous levels). It has been proposed to utilize distributed sensors associated with the electric lines to determine the temperature and / or stress state of the lines, allowing operators to alter the voltage and / or routing of electricity within the grid. While offering many advantages, these distributed sensors may require calibration and adjustment in order to provide accurate data to the electric line operators. Summary of the Invention

[0004] The present invention is directed to a method and system that allows for the calibration and / or validation of distributed sensors on an electrical line using non-distributed sensors. In one embodiment, a method for operating an overhead electric line operably mounted on a support tower is disclosed. The overhead electric line includes a first overhead electric cable having strength members and a conductor surrounding the strength members. The method includes a first distributed condition data acquisition step of acquiring first distributed condition data at a first time from first distributed sensing elements extending along a length of the first overhead electric cable, the first distributed condition data including one or more of first distributed cable temperature data and first distributed cable strain data, and a first location data acquisition step of acquiring first location data associated with the first distributed condition data, the first location data identifying a first linear section of the first distributed sensing elements, the first distributed condition data acquisition step and the first location data acquisition step comprising interrogating the first distributed sensing elements using interrogation devices operably attached to the first distributed sensing elements. determining a first distributed state value from the first distributed state data; acquiring first non-distributed state data from a first non-distributed sensor located proximate to a first linear section of the first distributed sensing element, the first non-distributed state data comprising data selected from the group consisting of first non-distributed cable temperature data and first non-distributed cable strain data; determining the non-distributed state value from at least the first non-distributed state data; and adjusting the interrogation device to reduce a difference between the first distributed state value and the first non-distributed state value.

[0005] The foregoing embodiments are subject to many refinements and characterizations. In certain characterizations, the strength members are fiber reinforced composite strength members. The fiber reinforced strength members may include reinforcing fibers in a polymer matrix. The fiber reinforced strength members may include reinforcing fibers in a thermoplastic matrix. The fiber reinforced strength members may include reinforcing fibers in a thermoset matrix. The fiber reinforced strength members may include reinforcing fibers in a metal matrix. The strength members may include a single composite strength element, or the strength members may include multiple composite strength elements.

[0006] The first distributed sensing element may extend along substantially the entire length of the overhead electrical cable. The first distributed sensing element may include a first optical fiber. The first optical fiber may be attached to a surface of the strength member. The first optical fiber may be embedded in the strength member. The first optical fiber may be a glass optical fiber.

[0007] The overhead electrical cable may have a length of about 100 meters or more. The overhead electrical cable may have a length of about 500 meters or more. The first straight section may have a length of about 10 meters or less.

[0008] In some characterizations, the first distributed state data may include first cable temperature data, and the first distributed state value is a temperature value. The first non-distributed sensor may be a thermocouple. The method may include applying heat to a portion of the first overhead electrical cable including the first non-distributed sensor during the step of acquiring the first distributed state data and the first non-distributed state data from the portion of the first overhead electrical cable. The interrogation device adjustment step may be performed if a difference between the first distributed state value and the first non-distributed state value is greater than a predetermined tolerance value. The predetermined tolerance value may be approximately 10°C or less in absolute value.

[0009] In another characterization, the first distributed state data may include first cable strain data, and the first distributed state value is a strain value. The first non-distributed sensor may be a strain gauge. The strain gauge may be operably attached to a strength member. The first non-distributed sensor may be a fiber Bragg grating ("FBG"). The overhead electric line may include a dead-end assembly that secures the first overhead electric cable to a support tower, and the first non-distributed sensor may be disposed within the dead-end assembly. In another characterization, the first non-distributed sensor may include a load cell attached to the first overhead electric cable. The interrogation device adjustment step may be performed if the difference between the first distributed state value and the first non-distributed state value is greater than a predetermined tolerance value. The predetermined tolerance value may be a strain value of approximately 0.001% or less in absolute value.

[0010] The interrogation device may include an OTDR device operably connected to the first optical fiber. The OTDR device may be a BOTDR device. The interrogation device adjustment step may include changing at least a first calibration factor of the OTDR device. The first non-dispersive sensor may be operably attached to the overhead electrical cable to obtain the first non-dispersive state data directly from the electrical cable. The first non-dispersive sensor may be located within the first linear section.

[0011] The method may also include acquiring second non-distributed condition data from a second non-distributed sensor located proximate the first linear section of the first distributed sensing element, the second non-distributed condition data including data selected from the group consisting of second non-distributed cable temperature data and second non-distributed strain data. The non-distributed condition value may be obtained from the first non-distributed condition data and the second non-distributed condition data. The method may also include acquiring third non-distributed condition data from a third non-distributed sensor, the third non-distributed condition data including data selected from the group consisting of third non-distributed cable temperature data and third non-distributed strain data.

[0012] In another embodiment, a system for operating an overhead electric line is disclosed. The system includes: an overhead electric line operably mounted on a support tower, the overhead electric line including a first overhead electric cable including a strength member and a conductor surrounding the strength member; a first distributed sensing element extending along a length of the first overhead electric cable, the first distributed sensing element including an optical fiber; an interrogation device operably attached to the optical fiber; and at least a first non-distributed sensor located proximate to the first overhead electric cable. The first non-distributed sensor can be selected from the group consisting of a temperature sensor and a strain sensor, and the first non-distributed sensor can be configured to measure one or more of a temperature value or a strain value of the overhead electric cable.

[0013] The above-described embodiments of the system for operating an overhead electric power line may be subject to many characterizations and refinements. In one characterization, the strength members are fiber reinforced composite strength members. The fiber reinforced strength members may include reinforcing fibers in a polymer matrix. The fiber reinforced strength members may include reinforcing fibers in a thermoplastic matrix. The fiber reinforced strength members may include reinforcing fibers in a thermoset matrix. The fiber reinforced strength members may include reinforcing fibers in a metal matrix. The strength members may include a single composite strength element, or the strength members may include multiple composite strength elements.

[0014] The first distributed sensing element may extend along substantially the entire length of the overhead electrical cable. The first distributed sensing element may include a first optical fiber. The first optical fiber may be attached to a surface of the strength member. The first optical fiber may be embedded in the strength member. The first optical fiber may be a glass optical fiber.

[0015] The overhead electrical cable may have a length of about 100 meters or more. The overhead electrical cable may have a length of about 500 meters or more. The first straight section may have a length of about 10 meters or less.

[0016] The first non-distributed sensor may include a thermocouple. The first non-distributed sensor may include an infrared camera. The first non-distributed sensor may include a strain gauge operably coupled to the strength member. The overhead electric line may include a dead-end assembly that secures the first overhead electric cable to a support tower, and the strain gauge is disposed within the dead-end assembly. The interrogation device may include an OTDR device operably attached to the optical fiber, such as a BOTDR device. [Brief explanation of the drawings]

[0017] [Figure 1] A diagram showing a portion of an overhead power line. [Figure 2] FIG. 1 is a cross-sectional view of an assembled dead end termination fixture. [Figure 3]FIG. 1 is a perspective view of an assembled and crimped dead end termination device. [Figure 4] Cross-sectional view of a splice useful for connecting two electrical cable segments. [Figure 5A] 1 is a perspective view of an overhead electrical cable including a fiber-reinforced composite strength member; [Figure 5B] 1 is a perspective view of an overhead electrical cable including a fiber-reinforced composite strength member; [Figure 6A] 1 is a cross-sectional view of a fiber reinforced composite strength member incorporating optical fibers embedded within the fiber reinforced composite material. [Figure 6B] 1 is a cross-sectional view of a fiber reinforced composite strength member incorporating optical fibers embedded within the fiber reinforced composite material. [Figure 7] FIG. 1 is a perspective view of an overhead electrical cable incorporating optical fibers on the surface of the strength members. [Figure 8] 1 is a perspective view of a portion of a power transmission line incorporating several non-distributed sensors. [Figure 9] FIG. 1 is a cross-sectional view of a non-distributed sensor placed in a dead-end fixture. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present disclosure relates to systems and methods for operating overhead electric power lines. As used herein, the term overhead electric power line encompasses both overhead transmission lines and overhead distribution lines. A transmission line is an electric power line configured to carry relatively high voltage (e.g., 60 kV or higher) electricity over long distances, such as from a power generation source to a substation, and a transformer is used to reduce the voltage from the transmission line and provide the lower voltage electricity to one or more distribution lines. A distribution line is an overhead electric power line configured to distribute lower voltage (e.g., less than 60 kV) electricity to a more localized area, such as from a substation to a surrounding area (e.g., a residential neighborhood or commercial complex). In either case, an overhead electric power line includes a long electrically conductive cable supported above ground by a series of support towers, sometimes called pylons. As described below, an overhead electric power line also includes other important components, such as hardware for attaching the electric cable to the support towers and insulators to prevent current leakage from the electric cable to the ground below.

[0019] 1 illustrates such an overhead power line 10, specifically an overhead transmission line. While the following description is primarily directed to systems and methods for operating transmission lines, it should be understood that the systems and methods may be employed with distribution lines as well, either separately or in combination with transmission lines. Power transmission line 10 includes an electrical cable, e.g., electrical cable 11, that conducts electricity and is supported above ground level by two or more support towers, such as support towers 12a / 12b / 12c. The electrical cable may have a length of about 20 meters or more, e.g., about 250 meters or more, about 500 meters or more, or about 1 kilometer or more.

[0020] Nevertheless, power transmission lines can span many kilometers, requiring very long lengths of spliced ​​electrical cable. As a result, an electrical line is typically composed of two or more electrical cable segments that are mechanically and electrically spliced ​​to form a continuous electrical path along the transmission line. Furthermore, a power transmission line includes multiple spaced-apart electrical cables, typically organized in groups of three, to support the transmission of three-phase alternating current (AC). While this disclosure primarily refers to AC transmission, the systems and methods disclosed herein are also useful for operating direct current (DC) power lines.

[0021] As mentioned above, one of the functions of a support tower is to safely elevate an electric cable above ground level. In this regard, the electric cable is attached to the support tower using various types of hardware. Some support towers are called dead-end towers or anchor towers, such as dead-end tower 12a. Such towers are located at termination points, such as substations or locations where the electric line enters underground. Dead-end towers such as dead-end tower 12a may also be needed when the electric line changes direction (e.g., bends), crosses roads or other structures that pose a high risk of damage or injury in the event of a cable failure, or is installed at regular intervals along a long, straight path. In such cases, two electric cable segments are mechanically attached to the dead-end tower under high tension and electrically connected to form a continuous electrical path. As shown in FIG. 1, electric cable segment 11a is secured (e.g., anchored) to dead-end tower 12a using dead-end termination equipment 13 (e.g., tension clamp) and electrically connected to adjacent electric cable segment 11b via electrical jumper 14. The electrical cable segments 11 a / 11 b are insulated from the dead-end tower 12 a by an insulator string 15 .

[0022] Another hardware component that may be used in power transmission lines is called a splice. While a single overhead cable segment may be thousands of meters long, power transmission lines may need to transmit power over hundreds of kilometers. To span such distances, linemen often must splice two cable segments. In this case, one or more splices may be utilized to join two electrical cable segments, for example, between two dead-end towers. The splice functions as both a mechanical joint, holding the two ends of the electrical cable segments together, and an electrical joint, allowing current to flow through the splice. As shown in FIG. 1, splice 16 operably connects electrical cable segment 17c to electrical cable segment 17d, forming both a mechanical joint and a continuous electrical pathway.

[0023] Figure 2 shows a cross section of an assembled termination device (e.g., dead end) such as dead end 13 shown in Figure 1. The dead end 20 shown in Figure 2 is similar to that shown and described in Bryant, International Publication No. WO 2005 / 041358, and Bryant et al., U.S. Patent No. 8,022,301, each of which is incorporated by reference herein in its entirety.

[0024] Broadly characterized, dead end 20 includes a gripping assembly 21 and a connector 22 for anchoring dead end 20 to, for example, a tower such as that shown in FIG. 1, using a fastener 23 disposed at a proximal end of dead end 20. At a distal end of dead end 20 opposite fastener 23, dead end 20 is operatively connected to overhead electrical cable segment 11, which includes conductors 24 surrounding and supported by strength member 25 (e.g., a fiber-reinforced composite strength member, sometimes referred to as a core).

[0025] Grip assembly 21 securely grips strength member 25 to secure overhead electrical cable segment 11 to dead end 20. As shown in FIG. 2 , grip assembly 21 includes a compression-type fitting (e.g., a wedge-type fitting), specifically, collet 26 having a collet lumen 27 (e.g., a bore) that surrounds and grips strength member 25. Collet 26 is disposed within collet housing 28, and when electrical cable segment 11 is under tension (e.g., pulled toward a support tower), friction develops between strength member 25 and collet 26 as the collet is pulled further into collet housing 28. The outer conical shape of collet 26 and the mating inner funnel shape of collet housing 28 increase compression of strength member 25, thereby ensuring that the strength member does not slip out of collet 26, thus securing overhead electrical cable segment 11 to dead end 20.

[0026] Connector 22 includes fastener 23 (e.g., an eyebolt) and gripping assembly mating threads 34 disposed on gripping assembly end 36 of connector body 35. To facilitate movement of connector 22 relative to collet 26, gripping assembly mating threads 34 are configured to operably mate with connector mating threads 37 on the interior surface of collet housing 28, such that when mating threads 34 and 37 engage and connector 22 is rotated relative to collet housing 28, collet 26 is forced into collet housing 28. This increases the compressive grip of collet 26 on strength member 25, further securing overhead electrical cable 11 to dead end 20. Fastener 23 is configured to attach to a dead end tower, as shown in FIG. 1, to secure dead end 20 and, thereby, electrical cable 11 to the dead end tower.

[0027] As shown in FIG. 2 , an outer sleeve 29 is positioned over the grip assembly 21 and the end of the electrical cable segment 11. The outer sleeve 29 includes a conductive body 30 for facilitating a continuous electrical path between the conductor 24 and a jumper plate 31. An inner sleeve 32 (e.g., a conductive inner sleeve) can be positioned between the conductor 24 and the conductive body 30 to facilitate an electrical connection between the conductor and the conductive body. The conductive body 30 may be fabricated from aluminum, and the jumper plate 31 may be integrally formed with or welded to the conductive body. The jumper plate 31 is configured to be attached to a connector plate 33 to facilitate forming an electrical path between the electrical cable segment 11 and another electrical cable segment (not shown), for example, via a jumper cable as shown in FIG. 1 .

[0028] FIG. 3 shows a perspective view of dead end 13 crimped (e.g., compressed) onto overhead electrical cable segment 11. Dead end 13 includes a connector having fasteners 23 extending outward from a proximal end of outer sleeve 29. Jumper plate 31 is integrally formed with outer conductive sleeve body 30 for electrical connection with a connection plate, as shown in FIG. 2. As shown in FIG. 3, outer sleeve conductive body 30 is crimped over (e.g., crimped onto) two regions of the underlying structure: crimp sleeve body region 30a and crimp sleeve body region 30b. Crimp sleeve body region 30b is generally positioned to cover a middle portion of the underlying connector, and crimp sleeve region 30a is generally positioned to cover a portion of electrical cable segment 11 (see, e.g., FIG. 2). The compressive force applied to the outer sleeve body 29 during the crimping operation is transmitted to the underlying components, i.e., the connector underlying crimp area 30b and the portion of the electrical cable segment 11 underlying crimp area 30a, permanently securing the conductive body 30 to the electrical cable segment 11 and the underlying connector.

[0029] The dead ends generally described with respect to Figures 2 and 3 can be utilized in a variety of overhead electrical cable configurations. The dead ends shown in Figures 2 and 3 are particularly useful for overhead electrical cables having fiber-reinforced composite strength members. For example, a compression wedge grip element having a collet disposed within a collet housing (e.g., Figure 2) allows fiber-reinforced composite strength members to be gripped under high compressive forces without significant risk of fracture of the composite material. However, those skilled in the art will recognize that other configurations of such dead ends are disclosed in the art, and that the foregoing illustration is merely an example of one configuration that may be used to secure an overhead electrical cable segment to a structure such as a support tower.

[0030] FIG. 4 shows a cross-sectional view of a splice 16 (e.g., a splice as shown in FIG. 1). As shown in FIG. 1, the splice is configured to mechanically and electrically connect the ends of two aerial cable segments to form a continuous electrical pathway between the two cable segments. As shown in FIG. 4, splice 16 connects two electrical cable segments 11 a and 11 b. Splice 16 includes gripping assemblies 21 a, 21 b that operably grip electrical cable segments 11 a, 11 b, respectively. The gripping assemblies may include, for example, a collet and housing configuration as shown in FIG. 2. To mechanically join the two electrical cable segments, gripping assemblies 21 a / 21 b are connected (e.g., threaded) to a single connector 22. To form a continuous electrical path between electrical cables 11a / 11b (e.g., between two conductors 24a / 24b), a conductive outer sleeve 29 is placed over the underlying structure and crimped onto at least the ends of connector body 22 and electrical cables 24a, 24b. Conductive inner sleeves 32a / 32b are inserted between conductors 24a / 24b and outer sleeve 29 to facilitate a robust electrical connection therebetween. As with the dead ends shown in Figures 2 and 3, those skilled in the art will recognize that other splice configurations are disclosed in the art and that the foregoing illustrations are merely examples that may be utilized to electrically and mechanically connect two electrical cable segments.

[0031] The systems and methods disclosed herein can be implemented in electric lines incorporating overhead electrical cables having a variety of configurations. One conventional configuration is called an aluminum conductor steel reinforced cable (ACSR) cable, in which an outer aluminum conductor strand is supported by a strength member having multiple steel wires twisted (e.g., stranded) to form the strength member. Other configurations implementing strength members formed from multiple twisted metal wires include aluminum core steel supported (ACSS) cable. These and similar configurations are known to those skilled in the art.

[0032] While the systems and methods disclosed herein can be implemented with electric lines incorporating these types of overhead electric cables, in certain embodiments, the systems and methods are particularly useful when the electric line incorporates one or more electric cable segments utilizing fiber-reinforced composite strength members. As used herein, a fiber-reinforced composite strength member is a strength member that includes elongated structural elements that include reinforcing fibers within a bonding matrix. Such composite materials offer many advantages, including light weight and advantageous mechanical properties such as high tensile strength and a low coefficient of thermal expansion (CTE), compared to metallic strength elements such as steel wire. Such strength members may include a single (i.e., not more than one) fiber-reinforced strength element (e.g., an integral fiber-reinforced composite strength member) or may be composed of several fiber-reinforced composite strength elements combined (e.g., twisted, stranded, or otherwise bundled) to form a strength member. As such, the present disclosure may use the terms strength member and strength element interchangeably, particularly when the strength member includes a single strength element.

[0033] The systems and methods disclosed herein can be utilized in electrical lines having one or more electrical cable segments incorporating strength members and one or more distributed sensing elements. The distributed sensing element is a long wire or strand that allows for location-specific data acquisition along the length of the distributed sensing element. In one particular characterization, the distributed sensing element includes one or more optical fibers. As used herein, the term optical fiber refers to a long, continuous fiber configured to transmit incident light along the length of the fiber. Typically, a glass optical fiber includes a transparent core and a cladding layer surrounding the core made of a different material (e.g., having a different refractive index) to reduce loss of light leaking from the transparent core to the exterior of the optical fiber. The optical fiber can be a single-mode optical fiber or a multimode optical fiber. A single-mode optical fiber has a small diameter transparent core (e.g., approximately 9 μm in diameter) surrounded by a cladding with a diameter of approximately 125 μm. A single-mode fiber is configured to allow only one mode of light to propagate. Multimode optical fibers have a larger transparent core (e.g., a diameter of about 50 μm or greater) that allows multiple modes of light to propagate. Optical fibers can be fabricated entirely from one or more polymers. However, polymer optical fibers may not have sufficient optical attenuation and suitable heat resistance to withstand the manufacture and / or use of strength members incorporating the optical fiber. In this regard, glass optical fibers are generally preferred due to, for example, their low attenuation.

[0034] Although the present disclosure contemplates the use of other types of distributed sensing elements, the present disclosure generally refers to the use of optical fibers. However, it should be understood that the present disclosure is not strictly limited to the use of optical fibers as distributed sensing elements, and that other distributed sensing elements may also be used.

[0035] As noted above, overhead electrical cables typically include a central strength member and conductors that are arranged around and supported by the strength members. While strength members have traditionally been fabricated from steel, such steel strength members are increasingly being replaced by strength members fabricated from composite materials (particularly fiber-reinforced composite materials), which offer a number of important advantages. Such fiber-reinforced composite strength members may include a single fiber-reinforced composite strength element, as shown in FIG. 5A. Alternatively, a composite strength member may be composed of multiple individual fiber-reinforced composite strength elements (e.g., individual rods) operably combined (e.g., twisted or stranded) to form a strength member, as shown in FIG. 5B.

[0036] Referring to FIG. 5A, overhead electrical cable 11A includes conductor 24A including a first layer of conductive strands 40a helically wrapped around fiber-reinforced composite strength member 25A, which includes a single fiber-reinforced composite strength element. A second layer of conductive strands 40b is helically wrapped around first conductive strand 40a to increase the volume of conductor 24A. Conductive strands 40a / 40b can be made from a conductive metal such as copper or aluminum, and for use in bare overhead electrical cables, are typically made from aluminum, e.g., hardened aluminum, annealed aluminum, and / or aluminum alloys. Conductive materials, such as aluminum, do not have sufficient mechanical properties (e.g., sufficient tensile strength) to be self-supporting when installed between support towers, thus necessitating the use of strength member 25A. 5A, the fiber-reinforced composite strength member 25A includes a single strength element having a high tensile strength section 41a (e.g., comprising carbon fiber) surrounded by a galvanic layer 42a that prevents adverse reactions between the carbon in the high tensile strength section 41a and the aluminum strands 40a. The galvanic layer 42a includes glass fibers that are also disposed in a bonding matrix and is integrally formed (e.g., pultruded) with the high tensile strength section 41a. Alternatively, the galvanic layer may be formed around the high tensile strength section by wrapping tape or placing a polymer around the high tensile strength portion.

[0037] FIG. 5B illustrates an embodiment of overhead electrical cable 11B similar to the electrical cable illustrated in FIG. 5A, where strength member 25B includes a plurality of individual fiber-reinforced strength elements (e.g., strength element 43B) stranded together to form strength member 25B. While illustrated in FIG. 5B as including seven individual strength elements, the multi-element strength member may include any number of strength elements suitable for a particular application. The individual strength elements may be formed of carbon fiber, and each element may include a galvanic layer, as illustrated in FIG. 5A. Alternatively or additionally, the strength element bundle may be generally surrounded by galvanic layer 42a, such as by wrapping insulating tape around the strength element bundle. Examples of such multi-element composite strength members include, but are not limited to, the multi-element aluminum matrix composite strength member shown in U.S. Patent No. 6,245,425 to McCullough et al., the multi-element carbon fiber strength member shown in U.S. Patent No. 6,015,953 to Tosaka et al., and the multi-element strength member shown in U.S. Patent No. 9,685,257 to Daniel et al., each of which is incorporated herein by reference in its entirety. Other configurations of fiber reinforced composite strength members may also be utilized in electrical cables.

[0038] As discussed above, the fiber-reinforced composite material from which the strength members are fabricated includes reinforcing fibers operatively disposed within a bonding matrix. The reinforcing fibers can be substantially continuous reinforcing fibers extending along the length of the fiber-reinforced composite material and / or can include short reinforcing fibers (e.g., fiber whiskers or chopped fibers) dispersed throughout the bonding matrix. The reinforcing fibers can be selected from a wide range of materials, including, but not limited to, carbon, glass, boron, metal oxides, metal carbides, high-strength polymers such as aramid fibers or fluoropolymer fibers, basalt fibers, and the like. Carbon fibers are particularly advantageous in many applications due to their very high tensile strength and / or their relatively low coefficient of thermal expansion (CTE).

[0039] The bonding matrix can include a plastic (e.g., a polymer), such as, for example, a thermoplastic or a thermosetting polymer. The bonding matrix can also be a metal matrix, such as an aluminum matrix. An example of an aluminum matrix fiber-reinforced composite is shown in U.S. Pat. No. 6,245,425 to McCullough et al., which is incorporated herein by reference in its entirety.

[0040] One particularly advantageous composite strength member configuration for overhead electrical cables is the aforementioned ACCC® composite configuration, available from CTC Global Corporation, Irvine, CA, and shown in U.S. Pat. No. 7,368,162 to Hiel et al. In commercial embodiments of the ACCC® electrical cable, the strength member is a single-element strength member of generally circular cross-section that includes an inner core of substantially continuous reinforcing carbon fibers disposed within a polymer matrix. The carbon fiber core is surrounded by a strong insulating layer of glass fibers, also disposed within the polymer matrix and selected to insulate the carbon fibers from the surrounding conductive aluminum strands. See FIG. 5A. Additionally, glass fibers have a higher modulus of elasticity than carbon fibers, providing flexibility that allows the strength member and electrical cable to be wound onto spools for storage and transportation.

[0041] While the foregoing properties of the fiber-reinforced strength members are disclosed as being desirable for use in overhead electrical cables, similar properties may be desirable when using the strength members disclosed herein in other structures, such as bridge cables or messenger cables.

[0042] In certain, but not limiting, embodiments, systems and methods for operating overhead electric power lines rely on the implementation of one or more distributed sensors. As used herein, a distributed sensor is a sensor capable of acquiring (e.g., measuring) data along a substantially continuous sensor length. For example, a distributed sensor may include an optical fiber extending along the length of an electric cable to detect temperature or strain along the entire length of the electric cable. In this manner, data collected and analyzed from the distributed sensor may also include identification of the location of the measurement along the distributed sensor. The distributed sensor may be associated with the electric cable by being disposed within the electric cable. For example, the distributed sensor may be disposed within conductive strands along the length of the electric cable. In some characterizations, optical fiber is associated with strength members of one or more electric cable segments. Operatively associating the optical fiber with the strength member may enable determining certain important characteristics of the strength member, such as strain in the strength member at a particular location.

[0043] In this regard, one or more elongated, continuous optical fibers can be operatively associated with the fiber-reinforced composite strength members. In some configurations, the optical fibers can be embedded within the fiber-reinforced composite material (e.g., within a bonding matrix). The optical fibers can extend from a first end of the strength member to a second end of the strength member, such that the entire length of the optical fiber, and substantially the entire length of the overhead electrical cable, can be interrogated using the optical fibers. Through appropriate optical fiber selection and optical fiber placement, the strength members and electrical cable segments can be interrogated to assess the condition of the strength members. While a single optical fiber can be utilized for the overhead electrical cable, the effectiveness of the systems and methods disclosed herein can be improved by including multiple optical fibers, one or more of which are associated with the strength members.

[0044] Referring to Figures 6A and 6B, cross-sectional views of a single-element fiber-reinforced composite strength member are shown. The configuration of the fiber-reinforced strength member is similar to the strength element shown in Figure 5A, including an inner section of high tensile strength fiber surrounded by an outer layer of insulating material, e.g., an inner section including carbon fiber surrounded by an outer galvanic layer including glass fiber. As shown in Figure 6A, fiber-reinforced composite strength member 25A includes a single optical fiber 44a that is centrally disposed within strength member 25A, i.e., centrally disposed within high strength section 41A. In other words, optical fiber 44a is disposed approximately along the central axis of strength member 25A. In the configuration shown in Figure 6B, the strength member is configured similarly to the configuration shown in Figure 6A. As shown in Figure 6B, strength member 25B includes a second optical fiber 44b in addition to optical fiber 44a. Optical fiber 44b is offset from optical fiber 44a, i.e., offset from the central axis of strength member 25B. In either case, the placement of one or more optical fibers along the central axis of the strength member can advantageously reduce or eliminate the effects of bending modes on the optical fiber. Examples of different configurations of optical fibers embedded within fiber-reinforced composite strength members are shown in Dong et al., U.S. Patent Application Publication No. 2021 / 0048469, which is incorporated herein by reference in its entirety.

[0045] It will be understood that Figures 6A and 6B are merely illustrative of possible configurations in which optical fibers may be operatively associated with fiber-reinforced composite strength members. For example, a fiber-reinforced strength member may incorporate more than one or two optical fibers (e.g., three, four, or more optical fibers). Such additional optical fibers may be used for improved measurement sensitivity, for redundancy, or for other reasons. In either case, certain advantages may be realized by incorporating the optical fiber within the fiber-reinforced composite strength member, e.g., within a bonding matrix. For example, the optical fiber is fully protected (e.g., shielded) from the external environment by the bonding matrix, ensuring that natural or man-made environmental factors (e.g., impact stress) do not significantly impair the performance of the sensing optical fiber. Furthermore, because the optical fiber is physically and intimately bonded to the matrix within the fiber-reinforced composite material, forces (e.g., tensile strain) acting on the fiber-reinforced composite strength member are fully and consistently transmitted to the optical fiber along the entire length of the strength member, ensuring accurate dispersion measurements.

[0046] Distributed sensing elements (e.g., optical fibers) can also be associated with fiber-reinforced strength members, and thus electrical cables that include strength members, by alternative means. For example, one or more optical fibers can be attached to the outer surface of the strength members along their lengths. FIG. 7 shows a perspective view of an exemplary embodiment of an overhead electrical cable 711 and a cross-sectional view of a strength member assembly 725 according to this construction. The electrical cable 711 includes a strength member assembly 725, which includes a strength member 725a having a high tensile strength fiber-reinforced composite core 725b including carbon fiber and a galvanic layer 725c of glass fiber in a bonding matrix. A conductor 724 surrounds the strength member assembly 725. In the embodiment shown in FIG. 7, the strength member assembly 725 includes an optical fiber 744 linearly arranged along the outer surface of the strength member 725a. A tape layer 725d is wrapped around the strength member 725a and the optical fiber 744 to couple the optical fiber to the strength member and form the strength member assembly 725. Specifically, tape layer 725d includes a strip of tape helically wrapped around strength member 725a in such a way that the tape overlaps itself along the seam, such that tape layer 725d covers the entire strength member (e.g., substantially without gaps) and optical fiber 744, with tape layer 725d positioned between optical fiber 744 and conductor 724 along its length. It will be understood that the structure shown in FIG. 7 is merely exemplary, and that optical fibers can be associated with electrical cables using other structures. Examples of such other structures are disclosed in WO 2021 / 222663 to Webb et al., which is incorporated herein by reference in its entirety.

[0047] The fiber-reinforced strength elements described above can be fabricated by means known to those skilled in the art. In one example, a fiber-reinforced composite strength member is formed by a pultrusion process, in which bundles of continuous reinforcing fibers (e.g., carbon and glass fibers) are drawn through a bonding matrix material (e.g., through a bath of epoxy resin) and then cured to bond the fibers and form the fiber-reinforced composite. Optical fibers are provided by manufacturers in continuous lengths (e.g., thousands of meters) on spools in a manner similar to fiber bundles (e.g., carbon fiber bundles, glass fiber bundles). Thus, optical fibers can be incorporated into the pultrusion process along with the reinforcing fibers.

[0048] The optical fiber may be operably coupled to an interrogation device that includes, for example, a coherent light source (e.g., a pump laser light source) that can pass (e.g., pulse) light through the optical fiber in a controlled manner. The light source may be configured to send a signal (e.g., pulses) along the optical fiber, and interrogation (e.g., measurement) of conditions within the optical fiber is performed by analyzing light backscattered by the optical fiber. In this regard, the interrogation device may include a signal detector (e.g., an interferometer) configured to detect the backscattered light signal.

[0049] For example, the components of backscattered light can be classified as Rayleigh, Brillouin, and Raman components. The backscattered Rayleigh component has the same frequency (i.e., same wavelength) as the primary light source and has a relatively high intensity. The backscattered Rayleigh component can be analyzed to determine the length of the optical fiber by using an optical time domain reflectometer (OTDR). Therefore, the backscattered Rayleigh component can be used to detect breaks in the optical fiber, which indicates possible damage to fiber-reinforced composite strength members. However, the backscattered Rayleigh component cannot provide additional significant information about the condition of the optical fiber.

[0050] In one characterization, the interrogation device performs OTDR analysis of one or more of the Raman backscattered light components (e.g., Raman distributed sensor) and the Brillouin backscattered light components (e.g., Brillouin distributed sensor). Both Raman and Brillouin distributed sensor systems utilize the nonlinear interaction between the primary optical signal and the optical fiber. When a primary optical signal of known wavelength is launched into the optical fiber, a small amount of the optical signal is scattered back (e.g., the backscattered optical signal) at every point along the optical fiber. The backscattered light contains shifted components at wavelengths different from the primary optical signal. The light components shifted to longer wavelengths (i.e., lower energy) are called Stokes components, and the light components shifted to shorter wavelengths (i.e., higher energy) are called anti-Stokes components. These shifted backscattered light components can be detected and analyzed to ascertain information about the local condition of the optical fiber, such as its strain and temperature, at various points along its length.

[0051] In one configuration, one or more of the optical fibers is utilized as a Raman dispersive temperature sensor. In a Raman dispersive temperature sensor, the interaction of a primary optical signal (e.g., a pump laser signal) with optical phonons in the optical fiber material (e.g., silica) produces two backscattered light components in the backscattered light spectrum: Raman Stokes and Raman anti-Stokes. The Raman anti-Stokes component is temperature dependent; that is, the intensity of the Raman anti-Stokes component increases as the temperature of the sensing optical fiber increases. As a result, the relative intensities of the Raman Stokes and Raman anti-Stokes backscattered light components can be measured and used to determine the temperature of the sensing optical fiber. The Raman Stokes and Raman anti-Stokes backscattered light components can be detected by a signal detector, such as an interferometer or a dispersive spectrometer, which may be a component of an interrogation device.

[0052] The Raman backscattered light components can also be used to determine the position of temperature readings along the length of the optical fiber. If a pulsed light signal is used to interrogate the optical fiber, the backscattered intensities of the Raman-Stokes and Raman anti-Stokes backscattered light components can be recorded as a function of time (e.g., "round trip" time), thereby allowing the temperature profile to be captured along the length of the optical fiber, i.e., along the length of the fiber-reinforced composite strength member.

[0053] In one example, the optical fiber operatively associated with the fiber-reinforced composite strength member includes a Raman distributed temperature sensor having a multimode sensing optical fiber. A multimode sensing optical fiber with a high numerical aperture can increase the intensity of the backscattered light, which can be important because the magnitude of the Raman backscattered light signal is relatively small.

[0054] In another configuration, the interrogation device incorporates Brillouin distributed sensing to interrogate the optical fiber. Brillouin distributed sensors utilize Brillouin backscattering, which is the result of the interaction of a primary optical signal with time-dependent optical density fluctuations (i.e., acoustic phonons) within the optical fiber. The acoustic phonons cause a periodic modulation of the refractive index (e.g., optical density) of the sensing optical fiber material. Brillouin scattering occurs when the propagating primary optical signal is diffracted by this moving "diffraction grating," resulting in frequency- and wavelength-shifted components in the backscattered optical signal.

[0055] As the temperature of the optical fiber increases, the wavelength of the Brillouin backscattered component shifts further from the dominant wavelength. This wavelength shift can be used to determine the temperature of the optical fiber. Similar to Raman distributed temperature sensors, the time-of-flight information in the backscattered optical signal can be used to determine the location of temperature readings along the length of the optical fiber.

[0056] However, unlike Raman dispersive sensors, Brillouin dispersive sensors can also be used to detect strain (e.g., tensile strain) in optical fibers. That is, changes in strain in the sensing optical fiber also cause wavelength shifts in the Brillouin backscattered light components due to changes in the optical density of the sensing optical fiber. As a result, the strain in the sensing optical fiber at any point along its length can be determined, and therefore the strain in fiber-reinforced composite strength members.

[0057] Brillouin distributed sensors can be configured to perform techniques based on spontaneous Brillouin, i.e., Brillouin optical time-domain reflectometry (BOTDR), or stimulated Brillouin, i.e., Brillouin optical time-domain analysis (BOTDA). One advantage of the BOTDR configuration is that it can utilize a single coherent pump light source, i.e., at one end of the sensing optical fiber. In certain systems, BOTDR also offers the ability to simultaneously measure temperature and strain in a single optical fiber. However, the detected backscattered optical signal is typically very weak, requiring signal processing and long integration times.

[0058] In another configuration, the Brillouin distributed interrogation device implements the BOTDA technique. BOTDA uses counter-propagating input optical signals (sometimes called "probe" or "counter wave" signals) with a wavelength difference equal to the Brillouin shift. This probe signal increases the density of phonons in the sensing optical fiber, resulting in a high signal-to-noise ratio. When the primary (pump) optical signal is a short pulse and its reflected intensity is analyzed in terms of time-of-flight and wavelength shift, it is possible to obtain a profile of the Brillouin shift along the length of the sensing optical fiber. The BOTDA technique generally requires that the wavelengths of the two counter-propagating optical signals are very stable (e.g., synchronized laser sources). Advantageously, temperature resolutions of less than 1.0°C or even less than 0.5°C can be achieved. Furthermore, very small strain shifts in the sensing optical fiber can be detected.

[0059] Thus, interrogation devices implementing Brillouin distributed sensing are useful for temperature monitoring and particularly well-suited for measuring strain. In this regard, calculating absolute temperature at any point along an optical fiber typically requires knowledge of the wavelength shift of the optical fiber at a reference temperature. Also, enabling absolute strain measurements typically requires knowledge of the wavelength shift of the unstrained fiber. In addition to temperature and strain, distributed sensing optical fibers can be used to detect vibrations and detect breaks in fiber-reinforced composite strength members.

[0060] In accordance with the present disclosure, characteristics of one or more overhead electrical cable segments can be interrogated (e.g., monitored) in real time during operation of the electrical line, e.g., during operation of an electrical grid, thereby enabling the systems and methods disclosed herein to actively monitor and operate the electrical line in real time. Such systems and methods may include, for example, continuously or semi-continuously interrogating the overhead electrical cable to detect the temperature state, strain state, mechanical load, and / or elongation of the overhead electrical cable, and acting in response to specific identified states. From the determination of these states, other conditions and / or states can be determined, such as the sag of a particular electrical cable segment or the current carried by the electrical cable segment.

[0061] One characteristic of such interrogation devices (e.g., OTDR interrogation devices) is that they must be calibrated to ensure that information received by the interrogation device is accurately converted into line condition values ​​(e.g., temperature values, strain values, etc.) during operation of the power line. In this regard, one or more calibration factors must be determined and implemented to accurately convert the raw data into the desired line condition values. Determination of such calibration factors may be determined prior to energizing the power line or at any time during operation of the power line as needed or desired. Furthermore, power line operators may desire to ensure that the line condition values ​​determined by the interrogation device are accurate by corroborating them with independently determined values.

[0062] In one embodiment of the present disclosure, a method for operating an overhead power line is disclosed in which measurements are made by distributed sensing elements associated with the overhead power line and the measurements are corroborated (e.g., verified) using one or more non-distributed sensors.

[0063] Thus, in some embodiments, one or more non-distributed sensors are utilized in conjunction with distributed sensors. Non-distributed sensors are sensors that are discretely (e.g., separated) placed at intervals along the line, for example, in proximity to the electrical cable. Examples of non-distributed sensors that may be useful for obtaining the temperature of the electrical cable include, but are not limited to, thermocouples and infrared cameras. Additionally, environmental sensors such as wind stations, humidity sensors, and the like may also be incorporated to collect data, for example, to further refine measurements.

[0064] FIG. 8 illustrates a portion of an overhead power line incorporating several non-distributed sensors. The power line 810 includes a segment of overhead electrical cable 811 located between two support towers 812a, 812b. A first non-distributed sensor 882 is directly attached to the electrical cable 811. The non-distributed sensor 882 can be characterized as a multi-function sensor, e.g., a sensor capable of detecting multiple characteristics of the electrical cable 811. An example of such a multi-function sensor is the TLM Transmission Line Monitor available from Lindsey Manufacturing Co. of Azusa, CA, as described in U.S. Patent Application Publication No. 2020 / 0209283 to Mohr et al., which is incorporated herein by reference in its entirety. Such a multi-function sensor may be capable of detecting cable clearance above ground, cable sag (e.g., using a tilt sensor), current, and temperature. These units are self-powered (eg, draw power from an electrical cable) and typically include an antenna for transmitting data, for example, using satellite or wireless communication techniques.

[0065] In some characterizations, the non-distributed sensors are not directly attached to the overhead electrical cable. For example, FIG. 8 also shows camera 886 mounted on support tower 821b in a manner that allows the camera to image overhead electrical cable 811. Camera 886 may include infrared capabilities to enable the camera to detect the temperature of electrical cable 811. Camera 886 may also include visible imaging capabilities, for example, so that image analysis can indicate sagging of electrical cable 811. Like multi-function sensor 882, camera 886 may include an antenna or similar device for wireless communication of data.

[0066] It will also be appreciated that non-distributed sensors may be utilized to collect data not directly available from the overhead electrical cable. For example, FIG. 8 illustrates a weather station 884 operably mounted on a support tower. Such weather station 884 may be capable of detecting ambient conditions such as wind speed, wind direction, solar radiation, humidity, and the like. Because these ambient conditions may affect the condition of the electrical cable, knowledge of these conditions may be useful in assessing the properties of the electrical cable, for example, using distributed sensors.

[0067] Other non-distributed sensors can be attached to an electrical cable in a manner that protects the sensor from the external environment and / or enables the sensor to detect specific conditions of the electrical cable. FIG. 9 illustrates one embodiment of such a non-distributed sensor. As shown in FIG. 9, a dead-end fixture 920 secures an overhead electrical cable 911, for example, in a manner similar to the dead-end fixture shown in FIG. 2. A gripping assembly 921 is secured to a strength member 925, for example, a strength member segment where the conductor 924 has been stripped to expose the strength member. A sensor 982 is attached directly to the exposed portion of the strength member 925, for example, using epoxy or other attachment means. In one characterization, the sensor 982 is a strain sensor that can measure strain in the strength member when coupled to the strength member. Because the sensor 982 is located between the gripping assembly 921 and the conductor 924, strain beneath the sensor indicates strain throughout the electrical cable 911. It is also advantageous to protect the sensor 982 from the environment when the dead-end fixture is installed, for example, by an outer sleeve 929. In this regard, access to the sensor 982 may be provided, for example, by leads 983a / 983b ported through the outer sleeve 929 as shown, or may be ported back through the grip assembly 921 and connector 922 for access through port 984.

[0068] As disclosed above, an overhead electric line is operably mounted on a support tower and includes at least a first overhead electric cable, as shown in FIG. 1 . The overhead electric cable includes strength members and conductors surrounding the strength members. The strength members can be fabricated from a metal, such as steel or aluminum, for example, in an ACSR configuration. In certain configurations, the electric cable includes a fiber-reinforced composite strength member. The fiber-reinforced composite strength member can include a matrix and reinforcing fibers disposed within the matrix. For example, the matrix can be a polymer matrix, such as a thermoplastic matrix or a thermoset matrix. Alternatively, the matrix can be formed from a metal, such as aluminum. The reinforcing fibers can include various types of fibrous materials, such as carbon fiber, glass fiber, aluminum oxide fiber, and the like. Furthermore, the strength member can include a single composite strength element, as shown in FIG. 5A , for example, or multiple strength elements, as shown in FIG. 5B .

[0069] The overhead electrical cable includes at least a first sensing element and may include two or more sensing elements. In some configurations, the transmitting element extends along substantially the entire length of the overhead electrical cable, for example, from a first end of the electrical cable to a second end of the electrical cable. In some structures, the distributed sensing element includes an optical fiber. The optical fiber may be attached to a surface of a strength member, for example, as shown in FIG. 7 above, or embedded within the strength member, for example, as shown in FIGS. 6A and 6B above. Alternatively or additionally, one or more optical fibers may be disposed within a conductor layer of the overhead electrical cable. In either case, the one or more optical fibers may be glass optical fibers, for example, multimode or single-mode glass optical fibers.

[0070] Overhead electrical cables may have relatively short lengths, e.g., lengths of about 10 meters or more and about 30 meters or less, for example, when utilized as a drop line to a substation or when the electrical cable passes over critical infrastructure. More commonly, overhead electrical cables have lengths of about 50 meters or more, e.g., about 100 meters or more, about 250 meters or more, or about 500 meters or more. Typically, overhead electrical cables have lengths not exceeding about 10 kilometers, such as not exceeding about 5 kilometers. The length of an overhead electrical cable is determined by the number of times strength members must be secured to dead ends or splices along the length of the electrical line, which can be several hundred kilometers.

[0071] The method for corroborating includes acquiring distributed condition data from distributed sensing elements (e.g., optical fibers). The distributed condition data may include distributed cable temperature data and / or distributed cable strain data. Both the distributed temperature data and the distributed strain data can be acquired from the distributed sensing elements (e.g., optical fibers) using an interrogation device such as an OTDR device (e.g., a BOTDR device), as disclosed above. The distributed condition data is collected by the interrogation device from the distributed sensing elements, at which time the distributed condition data is recorded and associated with the collected data. Additionally, first location data is collected and associated with the distributed condition data, and a linear position along the electrical cable is associated with the distributed condition data. The linear accuracy of the location data varies depending on many factors, including the time over which the distributed data is collected. Typically, the longer the time over which the distributed data is collected, the higher the measurement accuracy of the linear position of the data. Thus, the location data can identify a linear section along the overhead electrical cable, as opposed to a precise point. In other words, when condition data, such as temperature data, is collected, the condition data may be characterized as occurring within a length of the electrical cable between two points, e.g., within a straight section of the electrical cable, In one characterization, the straight section has a length of about 25 meters or less, e.g., about 20 meters or less, about 15 meters or less, about 10 meters or less, about 5 meters or less, or about 3 meters or less.

[0072] After collecting the dispersion state data, a first dispersion state value is determined (e.g., calculated) from the first dispersion state data. Stated another way, an interrogation device, such as an OTDR device, is configured to collect data from the sensing element, e.g., regarding the wavelength, frequency, and time-of-flight of the returning optical pulses, and calculate a state, e.g., a temperature or amount of strain, from that data. Typically, an OTDR device must be programmed with one or more calibration coefficients to accurately calculate the state based on the collected data. Such calibration coefficients can be entered into the interrogation device prior to installation of the overhead electrical cable.

[0073] While distribution condition data is very useful in assessing the condition of an overhead electrical cable along its length, the collected data is subject to changes in the overhead electrical cable, such as the effects of the overhead electrical cable's environmental and operating conditions over time. Thus, the collected data values ​​may deviate from the actual line condition over time to such an extent that the condition of the electrical cable makes the calculation of distribution condition from the collected data unreliable.

[0074] According to the method, non-distributed state data is collected from a non-distributed sensor located proximate to the overhead electrical cable, e.g., proximate to or within a linear section of the distributed sensing element from which the distributed data is collected. For example, the collected non-distributed state data may include data selected from temperature data and / or strain data. A non-distributed state value may be determined from the collected data. In one characterization, the non-distributed state value is used as a reference state value for that condition. In other words, if the non-distributed state value is temperature and the temperature from the non-distributed sensor is calculated to be 100°C, the reference state value is set to 100°C.

[0075] In one implementation, a state value deviation is calculated from the first distributed state value and the reference state value. For example, if the first distributed state value is 120° C. and the reference state value is 100° C., the state value deviation is about 20° C., or about +20%. As a result of this deviation, the first interrogation device can be adjusted, for example, with a new calibration factor, to reduce the state deviation value so that both the distributed and non-distributed sensors produce approximately the same value.

[0076] In another refinement, a second non-distributed sensor can be utilized to determine a baseline state value. The second non-distributed sensor can be co-located with the first non-distributed sensor, e.g., located proximate to, e.g., adjacent to, the first non-distributed sensor. If both the first and second non-distributed sensors agree on a state value, the state value can be set as a baseline value. If the non-distributed sensors disagree, e.g., if the measured temperature deviates by more than a few percent, the value of the non-distributed sensor can be taken into account. If the distributed sensing element and one of the non-distributed sensors agree, the state value can be taken as a baseline value and as an indication that adjustment of the interrogation device is not required. In this case, it may be desirable to investigate the second non-distributed sensor for repair or replacement.

[0077] If the line condition being determined is cable temperature, the non-distributed sensor may include a thermocouple. Thermocouples are utilized to calculate temperature based on the voltage generated at the junction of two dissimilar metals. Thermocouples are considered reliable due to their accurate temperature measurements over a wide temperature range. In one embodiment, heat may be applied to a portion of the first overhead electrical cable including the first non-distributed sensor while acquiring first distributed condition data and first non-distributed condition data from the portion of the first overhead electrical cable. This technique artificially heats the cable at this location to obtain more accurate readings from the distributed sensor, for example, by performing calibration and / or validation based on readings from the non-distributed sensor.

[0078] If the condition being interrogated is cable temperature, the acceptable deviation that triggers adjustment of the interrogation device may be predetermined. For example, the acceptable deviation may be about 20° C. or less in absolute value, e.g., within ±20° C. In another characterization, the acceptable deviation is about 15° C. or less in absolute value, e.g., about 10° C. or less in absolute value, or about 5° C. or less in absolute value.

[0079] In certain implementations, strain in an overhead cable, e.g., strain in a strength member, can be determined using a non-distributed sensing element. In this regard, the non-distributed sensor may include a strain gauge, e.g., a strain gauge operably attached to a strength member such that strain in the strength member is transmitted to the strain gauge. See, e.g., FIG. 9. As an alternative to or in addition to a strain gauge, the non-distributed sensor may include a fiber Bragg grating (“FBG”). Furthermore, the non-distributed sensor may include a load cell attached to the first overhead electrical cable to calculate strain in the strength member.

[0080] As discussed above, adjustment of the distributed sensors to reduce the condition deviation value can be performed when the condition deviation value is greater than a predetermined tolerance value. In one implementation where the condition is strain, the tolerance value is a strain value of about 0.01% or less in absolute value (e.g., within ±0.01%), e.g., about 0.005% or less in absolute value, about 0.001% or less in absolute value.

[0081] In one particular characterization, an overhead electric line includes a dead-end assembly that secures a first overhead electric cable to a support tower, and a non-distributed sensor, e.g., a strain gauge, is disposed within the dead-end assembly, as shown in FIG. 9. In this manner, the strain gauge can be disposed in a strength member section where the conductor has been stripped from the strength member. Furthermore, the strain gauge can be accessed through a fitting, e.g., through the dead end, by threading a wire from the strain gauge through the fitting to provide access.

[0082] In either case, the non-distributed sensors can collect data from the overhead electrical cable remotely, e.g., without direct contact with the electrical cable. For example, the temperature of the overhead electrical cable can be determined using an infrared camera focused on the electrical cable. In some characterizations, the non-distributed sensors are operably attached to the overhead electrical cable to obtain non-distributed condition data directly from the electrical cable. For example, thermocouples or strain gauges can be operably attached to the electrical cable, such as by attaching to a conductive layer or by attaching to a strength member. In this regard, the non-distributed sensors can be located within a first linear section. In this regard, the temperature or strain can be measured by the non-distributed sensors within a linear section known to contain non-distributed sensors. The non-distributed sensors can transmit data using known methods, such as satellite transmission and / or cellular radio transmission. The sensors can be powered directly by the overhead electrical cable, e.g., by inductive power. See FIG. 8.

[0083] Another characterization approach can utilize non-distributed sensors that incorporate multiple functions. For example, non-distributed sensors can measure not only cable temperature but also other parameters such as current, vibration, line sag, and / or ground clearance. See, for example, the TLM Transmission Line Conductor Monitor available from Lindsey Manufacturing Company of Azusa, CA, and U.S. Patent Application Publication No. 2020 / 0209283 to Mohr et al., which is incorporated herein by reference in its entirety. Collection of additional condition data, such as current, line sag, and the like, can be used to supplement temperature and strain calculations and provide a more comprehensive assessment of the line. See FIG. 8.

[0084] In another embodiment, a system configured to operate an overhead electric line is disclosed. For example, the system may include an overhead electric line operably mounted on a support tower, the overhead electric line including a first overhead electric cable including a strength member and a conductor surrounding the strength member. A first distributed sensing element extends along the length of the first overhead electric cable, for example, the first distributed sensing element includes an optical fiber. An interrogation device, such as an OTDR, is operably attached to the optical fiber. At least a first non-distributed sensor is located proximate to the first overhead electric cable, for example, to detect a condition of the electric cable. For example, the first non-distributed sensor can be selected from a temperature sensor and a strain sensor, for example, the first non-distributed sensor is configured to measure one or more of a temperature value or a strain value of the overhead electric cable. Thus, the system enables implementation of the aforementioned method, for example, calibration of the interrogation device and / or corroboration of the distributed sensor value with the non-distributed sensor value.

[0085] In another embodiment of the present disclosure, a non-distributed sensor (e.g., a non-distributed temperature sensor) can be utilized to extrapolate values ​​determined by a distributed sensing element (e.g., a distributed temperature value) to other portions of the electrical cable. For example, if a distributed sensing element, such as an optical fiber, is embedded within a fiber-reinforced composite strength member, the temperature measured by the distributed sensing element within the strength member may not be an accurate measurement of the temperature of the conductive strands surrounding the strength member. A non-distributed sensor placed on or near the conductive strand and accurately measuring the temperature of the conductive strand can be used as a reference point to allow the temperature of the strength member determined using the distributed sensing element to be extrapolated to provide the temperature of the conductive strand. Other data, such as wind or solar data collected from a weather station, can also be utilized to extrapolate temperature values ​​determined using the distributed sensing element.

[0086] While various embodiments of methods for operating an electrical line by corroborating dispersion measurements have been described in detail, modifications and adaptations of those embodiments will occur to those skilled in the art, and it is expressly understood that such modifications and adaptations are within the spirit and scope of the present disclosure.

Claims

1. 1. A method for operating an overhead electric line operably mounted on a support tower, the overhead electric line comprising: a first overhead electric cable comprising a strength member and a conductor surrounding the strength member; acquiring first distributed condition data at a first time from first distributed sensing elements extending along a length of the first overhead electrical cable, the first distributed condition data including one or more of first distributed cable temperature data and first distributed cable strain data; a first location data acquiring step of acquiring first location data associated with the first distributed state data, the first location data identifying a first linear section of the first distributed sensing element, the first distributed state data acquiring step and the first location data acquiring step including interrogating the first distributed sensing element using an interrogation device operably attached to the first distributed sensing element; determining a first dispersion state value from the first dispersion state data; acquiring first non-distributed condition data from a first non-distributed sensor located proximate to the first linear section of the first distributed sensing element, the first non-distributed condition data comprising data selected from the group consisting of first non-distributed cable temperature data and first non-distributed cable strain data; determining a non-dispersed state value from at least the first non-dispersed state data; and adjusting the interrogation device to reduce a difference between the first distributed state value and the first non-distributed state value.

2. The method of claim 1 , wherein the strength members are fiber reinforced composite strength members.

3. The method of claim 2 , wherein the fiber reinforced strength members comprise reinforcing fibers in a polymer matrix.

4. The method of claim 3 , wherein the fiber reinforced strength members comprise reinforcing fibers in a thermoplastic matrix.

5. The method of claim 3 , wherein the fiber reinforced strength members comprise reinforcing fibers in a thermosetting matrix.

6. The method of claim 2 , wherein the fiber reinforced strength members comprise reinforcing fibers in a metal matrix.

7. The method of any one of claims 1 to 6, wherein the strength member comprises a single composite strength element.

8. The method of any one of claims 1 to 6, wherein the strength member comprises a plurality of composite strength elements.

9. The method of any one of claims 1 to 8, wherein the first distributed sensing element extends along substantially the entire length of the overhead electrical cable.

10. The method of any one of claims 1 to 9, wherein the first distributed sensing element comprises a first optical fiber.

11. The method of claim 10 , wherein the first optical fiber is attached to a surface of the strength member.

12. The method of claim 10 , wherein the first optical fiber is embedded in the strength member.

13. The method according to any one of claims 10 to 12, wherein the first optical fiber is a glass optical fiber.

14. The method according to any one of claims 1 to 13, wherein the overhead electrical cable has a length of about 100 metres or more.

15. 15. The method of claim 14, wherein the overhead electrical cable has a length of about 500 meters or more.

16. The method of any one of claims 1 to 15, wherein the first straight section has a length of about 10 meters or less.

17. The method of any one of claims 1 to 16, wherein the first distribution condition data comprises first cable temperature data, and the first distribution condition value is a temperature value.

18. The method of claim 17 , wherein the first non-dispersive sensor comprises a thermocouple.

19. 19. The method of claim 17 or 18, further comprising applying heat to the portion of the first overhead electrical cable including the first non-distributed sensor during the step of acquiring the first distributed state data and the first non-distributed state data from the portion of the first overhead electrical cable.

20. 20. The method of claim 17, wherein the interrogation device adjustment step is performed if the difference between the first distributed state value and the first non-distributed state value is greater than a predetermined allowable deviation value.

21. 21. The method of claim 20, wherein the predetermined tolerance is no greater than about 10°C in absolute value.

22. The method of any preceding claim, wherein the first distribution state data comprises first cable strain data, and the first distribution state value is a strain value.

23. The method of claim 22 , wherein at least the first non-distributed sensor comprises a strain gauge.

24. 24. The method of claim 23, wherein the strain gauge is operably attached to the strength member.

25. 23. The method of claim 22, wherein at least the first non-dispersive sensor comprises a fiber Bragg grating ("FBG").

26. the overhead electric line includes a dead end assembly that secures the first overhead electric cable to a support tower; The method of any one of claims 23 to 25, wherein the first non-distributed sensor is disposed within the dead end assembly.

27. 23. The method of claim 22, wherein the first non-distributed sensor comprises a load cell affixed to the first overhead electrical cable.

28. 28. The method of any one of claims 22 to 27, wherein the interrogation device adjustment step is performed if the difference between the first distributed state value and the first non-distributed state value is greater than a predetermined allowable deviation value.

29. 30. The method of claim 28, wherein the predetermined tolerance is a distortion value of about 0.001% or less in absolute value.

30. A method according to any one of claims 10 to 29, wherein the interrogation device comprises an OTDR device operatively connected to the first optical fibre.

31. The method of claim 30, wherein the OTDR device is a BOTDR device.

32. 32. The method of claim 30 or 31, wherein the interrogation device adjustment step comprises changing at least a first calibration factor of the OTDR device.

33. 33. The method of any one of claims 1 to 32, wherein at least the first non-distributed sensor is operatively attached to the overhead electrical cable to acquire the first non-distributed condition data directly from the electrical cable.

34. The method of any one of claims 1 to 33, wherein the first non-dispersive sensor is located within the first linear section.

35. 35. The method of any one of claims 1 to 34, further comprising acquiring second non-distributed condition data from a second non-distributed sensor located proximate the first linear section of the first distributed sensing element, wherein the second non-distributed condition data comprises data selected from the group consisting of second non-distributed cable temperature data and second non-distributed strain data.

36. 36. The method of claim 35, wherein the non-distributed state value is obtained from the first non-distributed state data and the second non-distributed state data.

37. 37. The method of any one of claims 1 to 36, further comprising the step of acquiring third non-distributed condition data from a third non-distributed sensor, the third non-distributed condition data comprising data selected from the group consisting of third non-distributed cable temperature data and third non-distributed strain data.

38. 1. A system for operating an overhead power line, comprising: an overhead electric line operably mounted on a support tower, the overhead electric line comprising a first overhead electric cable comprising a strength member and a conductor surrounding the strength member; a first distributed sensing element extending along a length of the first overhead electrical cable, the first distributed sensing element comprising an optical fiber; an interrogation device operably attached to the optical fiber; at least a first non-distributed sensor located proximate to the first overhead electrical cable; the first non-dispersive sensor is selected from the group consisting of a temperature sensor and a strain sensor; The system, wherein the first non-distributed sensor is configured to measure one or more of a temperature value or a strain value of the overhead electrical cable.

39. 39. The system of claim 38, wherein the strength members are fiber reinforced composite strength members.

40. 40. The system of claim 39, wherein the fiber reinforced strength members comprise reinforcing fibers in a polymer matrix.

41. 41. The system of claim 40, wherein the fiber reinforced strength members comprise reinforcing fibers in a thermoplastic matrix.

42. 41. The system of claim 40, wherein the fiber reinforced strength members comprise reinforcing fibers in a thermosetting matrix.

43. 40. The system of claim 39, wherein the fiber reinforced strength members comprise reinforcing fibers in a metal matrix.

44. A system according to any one of claims 38 to 43, wherein the strength member comprises a single composite strength element.

45. A system according to any one of claims 38 to 43, wherein the strength member comprises a plurality of composite strength elements.

46. A system according to any one of claims 38 to 45, wherein the first distributed sensing element extends along substantially the entire length of the overhead electrical cable.

47. The system of any one of claims 38 to 46, wherein the first distributed sensing element comprises a first optical fiber.

48. 48. The system of claim 47, wherein the first optical fiber is attached to a surface of the strength member.

49. 48. The system of claim 47, wherein the first optical fiber is embedded in the strength member.

50. 50. The system of any one of claims 47 to 49, wherein the first optical fiber is a glass optical fiber.

51. A system according to any one of claims 38 to 50, wherein the overhead electrical cable has a length of about 100 metres or more.

52. 52. The system of claim 51, wherein the overhead electrical cable has a length of about 500 meters or more.

53. The system of any one of claims 38 to 52, wherein the first non-dispersive sensor includes a thermocouple.

54. The system of any one of claims 38 to 52, wherein the first non-distributed sensor includes an infrared camera.

55. 53. The system of any one of claims 38 to 52, wherein the first non-distributed sensor comprises a strain gauge operably coupled to the strength member.

56. 56. The system of claim 55, wherein the overhead electrical line includes a dead-end assembly that secures the first overhead electrical cable to a support tower, and the strain gauge is disposed within the dead-end assembly.

57. A system according to any one of claims 38 to 56, wherein the interrogation device comprises an OTDR device operably attached to the optical fibre.

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