POWER CABLE INTEGRATING AN AUTONOMOUS COMMUNICATING MEASUREMENT SYSTEM

Abstract

This power cable comprises at least one conductive element and further comprises: at least one means (36) for measuring at least one physical quantity; at least one electronic circuit (32), connected to the measurement means (36) and suitable for receiving from the at least one measurement means (36) at least one signal representative of the at least one physical quantity; and at least one energy harvesting system (30) disposed inside the cable, suitable for supplying the at least one electronic circuit (32) with electrical energy from the electrical energy available in the at least one conductive element.

Claims

1. A power cable comprising: at least one conductive element, and further having: at least one means for measuring at least one physical quantity; at least one electronic circuit, connected to said measurement means and suitable for receiving from said at least one measurement means at least one signal representative of said at least one physical quantity; and at least one energy harvesting system disposed inside said cable, suitable for supplying electrical energy to said at least one electronic circuit from the electrical energy available in said at least one conductive element.

2. The power cable as claimed in claim 1, wherein said electronic circuit is disposed inside the cable.

3. The power cable as claimed in claim 1, wherein said energy harvesting system comprises a plurality of coils mounted in series and/or in parallel, each coil of said plurality of coils having a magnetic core and a predetermined number of turns.

4. The power cable as claimed in claim 1, comprising at least two conductive elements, wherein said energy harvesting system is disposed in at least one gap between said at least two conductive elements, at a minimal distance from said at least two conductive elements, such that the flux density of the magnetic field generated by the electrical current circulating in said at least two conductive elements is maximal.

5. The power cable as claimed in claim 1, wherein said at least one measurement means is disposed inside said cable.

6. The power cable as claimed in claim 1, wherein said at least one measurement means is disposed on said cable.

7. The power cable as claimed in claim 1, wherein said cable comprises three or four conductive elements.

8. The power cable as claimed in claim 1, wherein said cable further comprises at least one radiofrequency device, suitable for transmitting to the outside of said cable data representative of said at least one signal representative of said at least one physical quantity.

9. The power cable as claimed in claim 1, wherein said cable further comprises an electrical energy storage means, suitable for storing the electrical energy harvested by said energy harvesting system.

10. The power cable as claimed in claim 1, wherein said at least one measurement means comprises a current-carrying capacity sensor suitable for measuring the maximum intensity admissible by said cable and/or a temperature sensor suitable for measuring the temperature in a predetermined region of said cable and/or a pressure sensor suitable for measuring the pressure in a predetermined region of said cable and/or an intensity sensor suitable for measuring the intensity of the electrical current flowing through said cable and/or an electrical voltage sensor suitable for measuring the electrical voltage at the terminals of a portion of said at least one conductive element and/or an electrical power sensor suitable for measuring the electrical power available in said cable and/or a mechanical tension sensor suitable for measuring the mechanical tension undergone by said cable and/or a location sensor suitable for determining the geographical location of a predetermined region of said cable and/or a vibration sensor suitable for measuring the vibrations in a predetermined region of said cable and/or a moisture sensor, suitable for determining the degree of moisture in a predetermined region of said cable and/or a gas flow rate sensor, suitable for determining the flow rate of a gas present in the environment of said cable and/or a gyroscopic sensor, suitable for determining the inclination of said cable.

11. The power cable as claimed in claim 1, wherein said cable further comprises at least one tube inside which is housed said at least one electronic circuit and/or said at least one energy harvesting system and/or said at least one measurement means.

12. The power cable as claimed in claim 10, wherein said at least one tube is cylindrical and has an outer diameter less than or equal to 25 mm.

13. A wind turbine tower, wherein said wind turbine tower comprises at least one cable as claimed in claim 1.

14. An electrical energy harvesting system for harvesting electrical energy via a magnetic field induced by a circulation of current, wherein said electrical energy harvesting system comprises a plurality of coils mounted in series, each coil of said plurality of coils having a magnetic core and a predetermined number of turns.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Other aspects and advantages of the invention will become apparent on reading the following detailed description of particular embodiments, given as nonlimiting examples, with reference to the attached drawings, in which:

[0051] FIG. 1 is a schematic representation of a cross section of a cable according to the present invention, in a particular embodiment;

[0052] FIG. 2 is an enlarged schematic representation of a coil with magnetic core included in a particular embodiment of a cable according to the present invention;

[0053] FIG. 3 is a functional schematic representation of elements relating to the cable according to the present invention, in a particular embodiment;

[0054] FIG. 4 is an enlarged schematic representation of a magnetic core of a coil included in a particular embodiment of a cable according to the present invention; and

[0055] FIG. 5 is a schematic representation of a three-phase cable according to the present invention, in a particular embodiment.

DESCRIPTION OF EMBODIMENT(S)

[0056] The cable according to the present invention is an electrical power cable intended for example to transport energy and/or to transmit data. As a nonlimiting example, it can be a cable used to supply a wind turbine tower.

[0057] FIG. 1 shows a cross-sectional view of a cable 10 according to the present invention, in a particular embodiment.

[0058] The cable 10 comprises at least one conductive element 12. In the particular embodiment illustrated, the cable is three-phase and therefore comprises three conductive elements 12.

[0059] The cable represented on the drawing comprises conductive elements 12 with a cross-section of circular form. Nevertheless, this form is given as a nonlimiting example. Other forms are possible, such as a substantially flat cross-section for example.

[0060] Around each conductive element 12, it is possible to provide one or more layers of insulating material, which are themselves possibly, but not necessarily, covered with a mechanical barrier, for example of braid or tape type.

[0061] Optionally, the cable 10 can also comprise an inner sheath 13 and an outer sheath 15, this exemplary embodiment not however being limiting.

[0062] According to the invention, as the functional diagram of FIG. 3 illustrates, the cable 10 further comprises at least one means 36 for measuring at least one physical quantity relating to the state of the cable and/or to a system of which the cable forms part and/or to the environment outside the cable. This measurement means 36 can be disposed either inside the cable 10, or on or close to it, such that the measurement means 36 is adjacent to the cable 10 or in its near environment. Optionally, it is possible to envisage interrogating the measurement means 36 by radiofrequency communication, via a radiofrequency device 38 of the type described hereinbelow, present in the cable 10.

[0063] Possible measurement means 36 that can be cited in particular, as nonlimiting examples, the following list moreover not being exhaustive, include: a current-carrying capacity sensor suitable for measuring the maximum intensity admissible by the cable 10, a temperature sensor suitable for measuring the temperature in a predetermined region of the cable 10, a pressure sensor suitable for measuring the pressure in a predetermined region of the cable 10, an intensity sensor suitable for measuring the intensity of the electrical current flowing through the cable 10, an electrical voltage sensor suitable for measuring the electrical voltage at the terminals of a portion of the at least one conductive element, an electrical power sensor suitable for measuring the electrical power available in the cable 10, a mechanical tension sensor suitable for measuring the mechanical tension undergone by the cable 10, a location sensor suitable for determining the geographic location of a predetermined region of the cable 10, a vibration sensor suitable for measuring the vibrations in a predetermined region of the cable 10, a moisture sensor, suitable for determining the degree of moisture in a predetermined region of the cable 10, a gas flow rate sensor, suitable for determining the flow rate of a gas present in the environment of the cable 10, a gyroscopic sensor, suitable for determining the inclination of the cable 10, etc.

[0064] One or more measurement means 36, suitable for measuring a same physical quantity or physical quantities of different natures, can be embedded in the cable 10.

[0065] The one or more measurement means 36 can also be suitable for measuring one or more parameters relating to the environment outside the cable 10, such as, for example, the presence of gas using the abovementioned gas flow rate sensor, or the presence of people, these examples not being limiting.

[0066] According to the invention, the cable 10 also comprises at least one electronic circuit 32, connected to the at least one measurement means 36 and suitable for receiving, from the at least one measurement means 36, at least one signal representative of the at least one physical quantity.

[0067] Optionally, the electronic circuit 32 can also be disposed inside the cable 10.

[0068] The function of the electronic circuit 32 is to condition the signal transporting the electrical energy collected by an energy harvesting system 30 described later, namely to rectify and store this signal, for example via one or more capacitors or accumulators, in order to stabilize the signal to make it available to the one or more measurement means 36.

[0069] To this end, the electronic circuit 32 can, as a nonlimiting example, comprise a rectifier bridge and a DC-DC converter of step-up type, also called “boost” or “buck” converter or series chopper.

[0070] According to the invention, the cable 10 further comprises at least one energy harvesting system 30, possibly, but not necessarily, disposed inside the cable 10 and suitable for supplying electrical energy to the at least one electronic circuit 32 from the electrical energy available in the at least one conductive element 12.

[0071] The electrical energy originating from the electrical current circulating in the conductive element or elements 12 is in fact collected by one or more energy harvesting systems 30, which use the magnetic flux induced by this circulation of current to harvest the energy therefrom and, optionally, store it in an electrical energy storage means 34 such as a miniature battery, this electrical energy storage means 34 being also able, but not necessarily, to be arranged inside the cable 10, for example in the form of one or more capacitors or accumulators, for example forming part of the electronic circuit 32 described above.

[0072] An energy harvesting system 30 of the type contained in the cable according to the invention can for example, but not necessarily, be of the type described hereinbelow.

[0073] The energy harvesting system 30 can comprise a single coil 16 of the type represented in FIG. 2, or a plurality of coils 16, which can be mounted in series, in parallel or both, so as to obtain sufficient voltage and power levels. The number of coils 16 depends on the application targeted and on the space available in the cable 10. The power harvested is proportional to the number of coils 16.

[0074] Each coil 16 has a magnetic core 160 and a predetermined number of turns 162.

[0075] The magnetic core 160 is produced, for example, in a soft ferromagnetic material, such as an alloy of iron and nickel, for example with at least 36% nickel, or else an alloy of iron and silicon, or else a ferrite, or a nanocrystalline alloy or an amorphous material.

[0076] The turns 162 constitute a coil of insulated wire. When the coil is placed in a magnetic field, the latter induces the circulation of a magnetic flux in the core, which in turn induces a voltage at the terminals of the coil that is proportional to the amplitude of this flux, to the section of the core and to the number of turns of the coil. In the cable 10, the coil 16 or the coils 16 mounted in series are advantageously placed close to the conductive element or elements 12 according to an arrangement that makes it possible to have a maximum flux density induced in the core 160 by the abovementioned magnetic field.

[0077] The best possible trade-off between the length and the magnetic section of the cores is chosen. For example, in order to increase the length/magnetic section dimensional ratio, by increasing the length of the bar that can constitute the core 160 without increasing its height and without reducing the magnetic section, provision can be made for the core 160 of the coil 16 to comprise an assembly of at least two plates, for example cut from a single block, for example three plates, including a central plate 1600 inclined with respect to the direction of the magnetic field and two end plates 1601 and 1602 on either side of the central plate and parallel to one another, as illustrated in FIG. 4.

[0078] Many variant embodiments of the core 160 can be envisaged: the core 160 can comprise only the central plate 1600, inclined or not with respect to the direction of the magnetic field, the core 160 can be made of a single piece or in several parts, possibly but not necessarily assembled together, etc.

[0079] In a particular embodiment in which the cable 10 is a three-phase cable, the coils 16 and their cores 160 can then be positioned, for example, as illustrated in FIG. 5.

[0080] For example, in a particular embodiment in which the cable 10 comprises at least two conductive elements 12, the energy harvesting system or systems 30 are disposed in at least one gap between these conductive elements 12, at a minimal distance therefrom, such that the flux density of the magnetic field generated by the electrical current circulating in the conductive elements 12 is maximal.

[0081] The cable 10 can comprise a variable number of conductive elements 12.

[0082] In a particular embodiment, the cable 10 comprises four conductive elements 12, including a neutral.

[0083] In the particular embodiment of FIG. 1, in which the cable 10 is a three-phase cable, that is to say comprises three conductive elements 12, a predetermined number of coils 16 mounted in series are disposed in the gap between each pair of adjacent conductive elements 12.

[0084] More generally, any embodiment of the energy harvesting system 30, possibly other than the coils 16, is disposed such that the preferred axis of operation of the energy harvesting system 30 is parallel to the field lines of the induced magnetic field. In a three-phase cable, for example, in which the currents in each conductive element 12 are phase-shifted by 120°, the radial component of the resultant field is maximal between two phases. The energy harvesting system 30 is therefore disposed between two phases and positioned such that its preferred axis of operation is parallel to the field lines.

[0085] Furthermore, in the particular embodiment of FIG. 1, the cable comprises three tubes 14 in which the coils 16 are housed.

[0086] More generally, the cable 10 can comprise at least one tube 14 inside which are housed, either one, or some, or all of the following elements: electronic circuit(s) 32, energy harvesting system(s) 30, one or more measurement means 36.

[0087] The tube or tubes 14 can be cylindrical or possibly of flattened form. Their cross-section is not necessarily circular or elliptical. It can be triangular, rectangular or take any other form deemed appropriate in the application concerned.

[0088] As a nonlimiting example, if the tube or tubes 14 are cylindrical, they can have an outer diameter less than or equal to approximately 20 to 25 mm, preferably less than or equal to approximately 15 mm, preferably less than or equal to approximately 8 mm. The value of this diameter best suited to the dimension of the cross-section of the cable 10 considered will be chosen.

[0089] Moreover, the tube or tubes 14 can have a length of several tens of cm and can contain, at predetermined distance intervals, several sets each composed of at least the following elements: an energy harvesting system 30, an electronic circuit 32 and a measurement means 36 and, optionally, an electrical energy storage device 34 and a radiofrequency device 38.

[0090] Nevertheless, the presence of one or more tubes 14 is optional: the cable 10 according to the present invention may not include any tube 14.

[0091] As a nonlimiting example, for a three-phase cable 10, with coils 16 each having a number of turns of the order of 500, a length of approximately 70 to 80 mm and a height of approximately 5 to 10 mm, a copper section of between approximately 0.005 mm.sup.2 and approximately 0.3 mm.sup.2 and a magnetic core having a section of between 1 mm.sup.2 and 3 mm.sup.2, when the average intensity of the current flowing through the cable 10 is approximately 100 A, an average voltage of between 60 mV and 70 mV with a maximum voltage exceeding 100 mV can be obtained.

[0092] In a particular embodiment, the cable 10 further comprises, optionally, one or more radiofrequency devices 38 (for example of RFID, “radiofrequency identification” type, or of WiFi type), suitable for transmitting out of the cable 10 data representative of the at least one signal representative of the at least one physical quantity.

[0093] The radiofrequency device or devices 38 can be incorporated in the electronic circuit 32. The one or more measurement means 36 can also be incorporated in the electronic circuit 32.

[0094] The energy harvesting system 30 contained in the cable 10 supplies electrical current by electromagnetism to the electronic circuit 32 and therefore to the at least one measurement means 36 which is connected to the electronic circuit 32. This supply is delivered for example at regular time intervals, this time interval for example being able to depend on the energy storage capacity of the electrical energy storage means 34.

[0095] The energy harvesting system 30 can further supply electrical current to any other element present in or on the cable 10. As a nonlimiting example, the energy harvesting system 30 can supply one or more light-emitting diodes arranged in or on the cable 10, which thus becomes a self-lit cable, also called lighting cable.

[0096] The present invention provides a large measuring modularity, a wide variety of physical quantities reflecting the state of the cable being able to be measured through the adaptation of the electronic circuit or circuits 32 and a possible modification of the number of energy harvesting systems 30 and/or, in a particular embodiment, a possible modification of the number of coils 16 that they contain as necessary, depending on the consumption requirements of the various measurement means 36 involved.

[0097] The present invention makes it possible to incorporate all of the functions described previously in an existing cable without increasing the dimensions thereof, by virtue of the miniaturization of the various components of this assembly. Nor does the invention require the cable manufacturing process to be modified.