New 25kV Combined Optical Current Transformer Sensitive Unit

Abstract

A novel 25 kV combined optical current transformer sensing unit, comprising: a 25 kV optical fiber composite bushing, the 25 kV optical fiber composite bushing including an embedded electrode and a core body; an optical fiber wound around the outer side of the core body in an S-shaped spiral; an upper flange disposed at one end of the 25 kV optical fiber composite bushing, and a current optical fiber sensing ring disposed in the upper flange; a lower flange disposed at the other end of the 25 kV optical fiber composite bushing, and a voltage optical sensing unit fixedly disposed relative to the lower flange. The present invention can simultaneously install a current optical fiber sensing ring and a voltage optical sensing unit, and the whole transformer is of a combined structure with high integration; an optical fiber is spirally wound around the core body, and both ends of the optical fiber pass through the upper and lower flanges and are provided with sealing rings for sealing treatment, and the sealing effect is good; the core body is integrally cast with epoxy resin, and the optical fiber is spirally wound around the outer surface of the core body, so that it is not easy to have a high-voltage breakdown and has excellent insulation performance, solving the insulation problem that it is difficult to combine optical current and voltage transformers.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and more specifically, to a novel 25 kV combined optical transformer sensing unit. Background Art

[0002] Transformers are necessary devices provided for power systems for metering, control, and relay protection.

[0003] Currently, in the fields of medium and low voltage power transmission and distribution, high-speed railways, and traction substations, most of the transformers used are of the electromagnetic induction application type. Such electromagnetic induction transformers have problems such as large volume, heavy weight, potential hidden dangers in external insulation, and difficulties in installation and maintenance. Summary of the Invention

[0004] In summary, how to solve the problems of large volume and difficult installation and maintenance existing in transformers in the prior art, especially electromagnetic induction transformers, has become an urgent problem to be solved by those skilled in the art.

[0005] The technical problem to be solved by the present invention is: overcoming the deficiencies of the prior art, providing a novel 25 kV combined optical transformer sensing unit. This sensing unit has a small volume, light weight, simple and reliable insulation, and good protection performance, and solves the insulation problem that is difficult to combine for optical current and voltage transformers. It realizes the high integration of the sensing unit and provides a new solution for the application of optical transformers in power systems, high-speed railways and other fields.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A novel 25 kV combined optical transformer sensing unit, which includes:

[0008] A 25 kV fiber composite bushing, the 25 kV fiber composite bushing includes an embedded electrode that is isopotentially connected to the high-voltage conductor with current to be measured, and a core body disposed around the embedded electrode. The core body is an insulating structure, and the tail end of the embedded electrode is located within the core body;

[0009] Optical fibers wound around the outside of the core body in an S-shaped spiral along the axial direction of the embedded electrode;

[0010] An upper flange disposed at one end of the 25 kV fiber composite bushing. One end of the optical fiber is led out from the upper flange, and a current fiber sensing ring is provided in the upper flange;

[0011] A lower flange disposed at the other end of the 25 kV fiber composite bushing. The other end of the optical fiber is led out from the lower flange, and a voltage optical sensing unit is fixedly disposed relative to the lower flange.

[0012] Preferably, in the novel 25 kV combined optical current transformer sensing unit provided by the present invention, a spiral core groove structure is arranged on the outer side surface of the core along the axial direction of the embedded electrode, and the optical fiber is arranged in the core groove structure.

[0013] Preferably, in the novel 25 kV combined optical current transformer sensing unit provided by the present invention, a silicone rubber umbrella group is arranged on the outer side of the 25 kV optical fiber composite bushing, and the optical fiber is arranged between the core and the silicone rubber umbrella group.

[0014] Preferably, in the novel 25 kV combined optical current transformer sensing unit provided by the present invention, a top flange clamping groove is arranged on the bottom surface of the top flange for clamping and fixing with the core, a top flange assembly hole is arranged through the bottom of the top flange clamping groove for equipotential connection between the high-voltage conductor to be measured and the embedded electrode, and a current-carrying end cover is arranged on the upper side surface of the top flange.

[0015] Preferably, in the novel 25 kV combined optical current transformer sensing unit provided by the present invention, the top flange clamping groove is in interference fit with the core; an isolation insulating ring is arranged between the top flange and the current-carrying end cover; a circular groove coaxial with the top flange assembly hole is arranged on the upper side surface of the top flange, the circular groove is located within the isolation insulating ring, and the current optical fiber sensing ring is arranged in the circular groove.

[0016] Preferably, in the novel 25 kV combined optical current transformer sensing unit provided by the present invention, a bottom flange clamping groove is arranged on the upper side surface of the bottom flange for clamping and fixing with the core, and the optical fiber passes through and is led out from the bottom flange; a basin body is arranged on the bottom surface of the bottom flange, the basin body has a mounting table arranged at the tail end facing the embedded electrode, and a voltage optical sensing unit is arranged on the mounting table, the voltage optical sensing unit is arranged at the tail end facing the embedded electrode; the optical fiber is arranged in a coiled manner on the lower side of the mounting table after passing through the bottom flange; a bottom cover is fixedly connected to the bottom surface of the basin body.

[0017] Preferably, in the novel 25 kV combined optical current transformer sensing unit provided by the present invention, the mounting table is of a frustum structure and is coaxial with the embedded electrode; a circular basin groove is arranged on the bottom surface of the basin body, the circular basin groove is coaxial with the embedded electrode, and the optical fiber coiling coil is arranged in the circular basin groove.

[0018] Preferably, in the novel 25 kV combined optical current transformer sensing unit provided by the present invention, a sealing ring is provided between the isolation insulating ring, the current-carrying end cover and the upper flange; a sealing ring is provided between the lower bottom cover and the basin body; a sealing ring is provided between the basin body and the lower flange; a terminal block is provided on the upper flange and / or the current-carrying end cover.

[0019] Preferably, in the novel 25 kV combined optical current transformer sensing unit provided by the present invention, the silicone rubber umbrella skirt includes an umbrella skirt main body in a cylindrical structure, and an annular silicone rubber umbrella is provided on the outer side surface of the umbrella skirt main body, and the silicone rubber umbrellas are arranged at intervals along the axial direction of the embedded electrode.

[0020] Preferably, in the novel 25 kV combined optical current transformer sensing unit provided by the present invention, the core is an epoxy resin core, the core is a cylindrical structure coaxially arranged with the embedded electrode, and the core is cast on the outside of the embedded electrode.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The present invention provides a novel 25 kV combined optical current transformer sensing unit, which includes: an embedded electrode that is isopotentially connected to a to-be-measured current-carrying high-voltage conductor, the embedded electrode is in a columnar structure, the head end of the embedded electrode is used for isopotential connection with the to-be-measured current-carrying high-voltage conductor, and an electric field can be generated around the embedded electrode; a core arranged on the periphery of the embedded electrode, the core is an insulating structure, and the tail end of the embedded electrode is located inside the core; an optical fiber arranged on the outside of the core in a spiral winding manner along the axial direction of the embedded electrode, polarized light is transmitted by the optical fiber, one end of the optical fiber is an input end connected to a current optical fiber sensing ring, the other end of the optical fiber is an output end connected to a demodulation unit, the input end and the output end are led outwards relative to the core, and after the optical fiber is arranged on the core, installation positions can be formed at both ends in the axial direction of the core, and the installation positions are used for installing auxiliary measuring elements. For example, a current optical fiber sensing ring is arranged near the head end of the embedded electrode; a voltage optical sensor unit is arranged near the tail end of the embedded electrode, wherein the current optical fiber sensing ring and the voltage optical sensor unit are both auxiliary measuring elements.

[0023] It should be noted that: The focus of the present invention is to provide an optical current transformer with a bushing structure, that is, the above-mentioned core combination structure provided with an embedded electrode and an optical fiber wound around the outside, and based on the transformer with this bushing structure, the present invention can also install auxiliary measurement elements at both ends of the core, such as a current optical fiber sensing ring and a voltage optical sensor unit, so that the present invention forms a new type of 25 kV combined optical current transformer sensing unit.

[0024] Through the above structural design, compared with the prior art, the advantages of the present invention are as follows:

[0025] 1. The current optical fiber sensing ring and the voltage optical sensing unit can be installed simultaneously, and the whole transformer is of a combined structure with high integration;

[0026] 2. The optical fiber is spirally wound around the core, and both ends of the optical fiber pass through the upper and lower end flanges and are provided with sealing rings for sealing treatment, with good sealing effect;

[0027] 3. The core is integrally cast with epoxy resin, and the optical fiber is spirally wound around the outer surface of the core, so it is not easy to have high-voltage breakdown and has excellent insulation performance;

[0028] 4. The present invention realizes a closed and non-contact method (the closed type means that the optical fiber sensing ring, the voltage sensing unit and the optical fiber are all in a closed space, with excellent dust-proof, waterproof and anti-corrosion performance and strong environmental adaptability. The non-contact type means that there is no contact between the optical fiber sensing ring and the current-carrying conductor, and there is no contact between the voltage sensing unit and the high-voltage end, and the current and voltage signals can be measured by a non-contact method), reducing the interference of the external environment, reducing the insulation hidden danger and improving the measurement accuracy;

[0029] 5. Both the current-carrying end cover and the upper end flange are provided with terminal blocks. The current passes through the inside of the current optical fiber sensing ring from the contact surface between the current-carrying end cover and the upper end flange and flows out (the current flows in from the terminal of the current-carrying end cover, passes through the optical fiber sensing ring through the middle part of the current-carrying end cover and then flows out from the terminal of the upper end flange). The current optical fiber sensing ring is arranged in a lying manner, reducing the overall height;

[0030] 6. After the embedded electrode and the epoxy resin core are integrally formed, a silicone rubber umbrella skirt (silicone rubber umbrella skirt) is cast, which not only ensures the internal insulation (the internal insulation refers to the insulation method adopted to prevent the high-voltage part from conducting and breaking down between the internal dielectric and the grounding end, for example, the embedded electrode is wrapped with epoxy resin), but also ensures the external insulation (the external insulation refers to the insulation method adopted to prevent the high-voltage part from conducting and breaking down between the external surface of the dielectric and the grounding end, for example, the silicone rubber umbrella skirt), improving the overall structural strength and insulation strength of the present invention;

[0031] 7. The present invention is small in volume, light in weight, has simple and reliable insulation, high integration, and good protection, solving the insulation problem that is difficult to combine for optical current and voltage transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. Among them:

[0033] Figure 1 is a schematic structural diagram after the embedded electrode and the core are assembled on the sensitive unit of the novel 25 kV combined optical transformer in the embodiment of the present invention;

[0034] Figure 2 is a schematic overall structural diagram of the sensitive unit of the novel 25 kV combined optical transformer in the embodiment of the present invention;

[0035] Figure 3 is a schematic structural diagram of the upper flange in the embodiment of the present invention;

[0036] Figure 4 is a top view of the upper flange in the embodiment of the present invention;

[0037] Figure 5 is a schematic structural diagram of the current-carrying end cover in the embodiment of the present invention;

[0038] Figure 6 is a top view of the current-carrying end cover in the embodiment of the present invention.

[0039] In Figures 1 to 6 the correspondence between the component names and the reference numerals of the drawings is as follows:

[0040] Current-carrying end cover 1, isolation insulation ring 2, current optical fiber sensitive ring 3, 25 kV optical fiber composite bushing 4, inner sealing ring 5 provided between the lower flange and the basin body, bolt 6 for connecting the lower flange and the basin body, outer sealing ring 7 provided between the lower flange and the basin body, basin body 8, bottom cover 9, voltage optical sensing unit 10, sealing ring 11 provided between the upper flange and the current-carrying end cover, insulating particle 12, bolt 13 for connecting the upper flange and the current-carrying end cover, nut 14, upper flange 15, silicone rubber umbrella group 16, core 17, embedded electrode 18, lower flange 19, optical fiber 20. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. Each example is provided by way of explanation of the present invention rather than a limitation thereof. In fact, those skilled in the art will appreciate that modifications and variations can be made to the present invention without departing from the scope or spirit thereof. For example, features shown or described as part of one embodiment can be used in another embodiment to yield yet another embodiment. Accordingly, it is intended that the present invention encompass such modifications and variations as fall within the scope of the appended claims and their equivalents.

[0042] In the description of the present invention, the orientation or positional relationships indicated by the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention rather than requiring the present invention to be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention. The terms "connected" and "coupled" used in the present invention should be understood in a broad sense. For example, they can be fixedly connected or detachably connected; they can be directly connected or indirectly connected through an intermediate member. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0043] Please refer to Figures 1 to 6 , wherein Figure 1 is a schematic structural diagram of the assembled inner-embedded electrode and core body of the novel 25 kV combined optical current transformer sensing unit in an embodiment of the present invention; Figure 2 is a schematic overall structural diagram of the novel 25 kV combined optical current transformer sensing unit in an embodiment of the present invention; Figure 3 is a schematic structural diagram of the upper flange in an embodiment of the present invention; Figure 4 is a top view of the upper flange in an embodiment of the present invention; Figure 5 is a schematic structural diagram of the current-carrying end cover in an embodiment of the present invention; Figure 6 is a top view of the current-carrying end cover in an embodiment of the present invention.

[0044] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a novel 25 kV combined optical current transformer sensing unit sensitive component, which should have the advantages of small volume, light weight, simple and reliable insulation, good protection, etc. At the same time, the optical current and voltage transformer sensitive component should also be able to solve the insulation problem that is difficult to combine for optical current and voltage transformers.

[0045] The present invention provides a novel 25 kV combined optical current transformer sensing unit, which can realize optical measurement (optical measurement) of current and voltage.

[0046] In the present invention, the novel 25 kV combined optical current transformer sensing unit has the following composition structure:

[0047] 1. Embedded electrode.

[0048] The embedded electrode is a metal conductor structure that can be isopotentially connected to the high-voltage conductor carrying current to be measured. This invention is applied to high-voltage circuit systems (25 kV and above), which are AC systems. After the embedded electrode is isopotentially connected to the high-voltage conductor carrying current to be measured, it can generate an electric field, thereby realizing the optical measurement of the voltage and current of the high-voltage conductor carrying current to be measured.

[0049] In an embodiment of the present invention, the main body of the embedded electrode is a round bar structure. A terminal post coaxial with it is provided at the head end of the embedded electrode, and a nut is provided on the terminal post. A ball head structure is provided at the tail end of the embedded electrode. And corresponding to this structure (a ball head structure is provided at the tail end of the embedded electrode), the present invention provides a concave spherical groove structure (arc groove) (specifically, concave upward) at the bottom of the core body. The arc groove opened on the core body is for the purpose of controlling the thickness of the epoxy resin and air gap between the ball head structure end of the embedded electrode and the boss (mounting table) where the voltage sensing unit is located, so that the thickness ratio of the two is appropriate, thereby making the electric field intensity distribution more conducive to the sensing unit for measurement.

[0050] Furthermore, the embedded electrode is an integral structure.

[0051] In the present invention, the embedded electrode is made of a metal material with good electrical conductivity, such as pure copper. In an embodiment of the present invention, the main body part of the embedded electrode is a cylinder structure (round bar structure), and the outer side surface of the embedded electrode is a rough matte surface structure (facilitating high-strength bonding with the core body). And the tail end of the embedded electrode adopts a ball head type structure (in this way, the occurrence of partial discharge caused by excessive local charge accumulation in the embedded electrode can be avoided. If there is a sharp structure locally in the embedded electrode, then too much charge will accumulate at the sharp structure, resulting in a discharge situation). In addition, the embedded electrode is provided with a ball head structure, and another function is: adopting the classical model "sphere-plate" model in the calculation of electric field intensity, the spherical structure can make the electric field distribution more uniform, which is beneficial to electrical insulation, and at the same time can also enhance the local electric field intensity at the boss of the basin body, which is beneficial to electric field measurement.

[0052] A terminal post is provided at the head end of the embedded electrode. The terminal post is a round bar structure (the diameter of the terminal post is smaller than the diameter of the embedded electrode). It should be noted that: the terminal post is mainly for making the embedded electrode in isopotential contact with the upper flange. The terminal post and the embedded electrode can be coaxially arranged or non-coaxially arranged. In addition, since the terminal post is shielded in the isopotential conductor and no charge accumulation will occur, the terminal post can also not be rounded.

[0053] The embedded electrode is in a cylindrical structure. The head end of the embedded electrode is used for isopotential connection with the high-voltage conductor with current to be measured. After the isopotential connection (equal-potential connection) with the high-voltage conductor with current to be measured, it has a high voltage potential, and an electric field is generated around the embedded electrode.

[0054] In the present invention, a core body is arranged outside the embedded electrode. The lower end of the core body wraps the spherical head structure at the bottom end of the embedded electrode. The embedded electrode is charged with 25 kV voltage. There are strong electric fields both between the embedded electrode and the tip of the lower flange and between the embedded electrode and the mounting table of the basin body. This electric field can break down the air and cause discharge damage. However, the electric strength resistance of epoxy resin (the manufacturing material of the core body) is much greater than that of air. Therefore, using epoxy resin as the core body to wrap the bottom end of the embedded electrode can wrap the easily discharged parts such as the embedded electrode and the tip of the basin body, eliminating the discharge phenomenon and improving the overall insulation performance.

[0055] 2. Core body.

[0056] The core body is an insulator arranged around the embedded electrode. The core body is an insulating structure made of insulating materials, and the tail end of the embedded electrode is located inside the core body.

[0057] In a preferred embodiment of the present invention, the main body part of the embedded electrode is entirely located inside the core body. The head end of the embedded electrode can be flush with one end face of the core body, or the main body part of the embedded electrode is entirely arranged inside the core body and only the terminal post passes through the core body. The core body should have a certain structural strength and excellent insulation at the same time. Therefore, the present invention preferably uses epoxy resin as the manufacturing material of the core body to manufacture an epoxy resin core body. As described above, the main body part of the embedded electrode adopts a cylindrical (round bar) structure. In the present invention, the core body adopts a cylindrical structure coaxially arranged with the embedded electrode, and moreover, the core body is cast and formed on the outside of the embedded electrode. This can not only improve the structural tightness between the embedded electrode and the core body, but also the core body is not restricted by the structural form of the embedded electrode on the embedded electrode, improving the flexibility of the structural form design of the embedded electrode.

[0058] In the present invention, the main body of the embedded electrode is in a round bar structure. The head end of the embedded electrode is provided with a terminal post coaxially arranged with it. External threads are provided on the outer side surface of the terminal post, and nuts are provided on the connecting post, so that the isopotential connection wire can be fixed by the nuts.

[0059] The present invention arranges a core body outside the embedded electrode. The core body is preferably cast with epoxy resin on the outside of the embedded electrode. The structure formed by the core body and the embedded electrode has a relatively high structural strength, and at the same time, the core body can also play a role in protecting and insulating the embedded electrode. Since the structural strength of the core body is relatively high, other structures such as an upper flange and a lower flange can be arranged on the core body in the present invention.

[0060] 3. Optical fiber.

[0061] The present invention uses a magneto-optical material as the manufacturing material of the optical fiber. At the same time, the optical fiber also has a certain toughness and structural strength (which can enable the optical fiber to be wound around the core). Polarized light can not only propagate in the optical fiber, but also be deflected under the action of a periodically changing electric field during the propagation in the optical fiber.

[0062] Specifically, the optical fiber is arranged on the outer surface of the core in a spiral winding manner along the axial direction of the embedded electrode. In the present invention, the optical fiber arranged outside the core is used to transmit the optical signal deflected by the current in the current fiber sensing ring. Polarized light is propagated by the optical fiber. One end of the optical fiber is the input end connected to the current fiber sensing ring, and the other end of the optical fiber is the output end connected to the demodulation unit. The input end and the output end are led out relative to the core. The optical fiber is arranged on the outer side surface of the core in a bolt winding manner, and the embedded electrode is arranged inside the core in a rod structure. After the embedded electrode is energized, an electric field can be generated.

[0063] In the present invention, the upper end of the embedded electrode is connected to the same potential as the high-voltage conductor to be measured for current. The upper flange, the embedded electrode, and the current-carrying end cover are all high-voltage ends, and the lower flange and the basin body are grounding ends. The high-voltage insulation characteristics such as the insulation distance and the creepage distance need to be satisfied between the high-voltage end and the grounding end. The optical fiber is arranged on the outside of the core in an S-shaped spiral winding manner, which can increase the creepage distance, that is, the path through which the high-voltage side passes through the optical fiber and the grounding end increases if breakdown occurs (if it is arranged in a straight line, the path is the shortest and it is most likely to be broken down). Therefore, the S-shaped spiral winding structure of the optical fiber can improve the insulation strength and prevent the bushing from being broken down.

[0064] The optical fiber is arranged on the outer surface of the core and in a spiral winding manner. In order to improve the firmness of the optical fiber arranged on the core, the present invention is provided with a spiral core groove structure on the outer side surface of the core and along the axial direction of the embedded electrode. The groove width of the core groove structure is equal to the diameter of the optical fiber, and the groove depth of the core groove structure is equal to the radius of the optical fiber. The optical fiber is arranged in the core groove structure, and half of the structure of the optical fiber is located in the outer surface of the core. After a silicone rubber umbrella group is arranged on the outside of the core, the exposed part (the part located outside the outer surface of the core) of the optical fiber can be pressed and fixed by the silicone rubber umbrella group, so that the firmness of the optical fiber arranged on the outer surface of the core can be maximally improved.

[0065] 4. Current fiber sensing ring.

[0066] The current fiber sensing ring is an optical current transformer element that can detect the magnitude of current. The current fiber sensing ring is arranged at a position close to the head end of the embedded electrode and can detect the magnitude of the current flowing into the fiber sensing ring from the current-carrying end cover.

[0067] 5. Voltage optical sensor unit.

[0068] The voltage optical sensor unit is an optical transformer component capable of detecting the magnitude of voltage. The voltage optical sensor unit is arranged at a position close to the tail end of the embedded electrode and can detect the magnitude of the voltage of the embedded electrode.

[0069] The current optical fiber sensitive ring is of a ring structure, and a sensing optical fiber is wound inside the ring. The sensing optical fiber measures the current through the Faraday magneto - optical effect. Specifically, a periodically changing electric field is generated around the current, and the periodically changing electric field will cause a change in the deflection direction of the optical signal in the optical fiber. The magnitude of this deflection direction is proportional to the magnitude of the current.

[0070] The voltage optical sensing unit is of a strip - shaped crystal structure. The optical signal enters from one end of the crystal and returns from the other end. According to the Pockels effect, the optical signal in the crystal is affected by the electric field generated by the embedded electrode and generates an additional phase. This additional phase is proportional to the electric field strength, and the electric field strength is proportional to the voltage, thereby measuring the voltage value.

[0071] 6. Silicone rubber umbrella group.

[0072] The silicone rubber umbrella group is an insulating structure. The silicone rubber umbrella group is arranged on the outer side of the core body, and the optical fiber is clamped between the core body and the silicone rubber umbrella group. The silicone rubber umbrella group can not only improve the insulation performance of the core body but also play a protective role for the optical fiber.

[0073] Furthermore, the silicone rubber umbrella group includes an umbrella group main body of a cylindrical structure, and an annular silicone rubber umbrella is arranged on the outer side surface of the umbrella group main body. The silicone rubber umbrellas are arranged at intervals along the axial direction of the embedded electrode.

[0074] 7. Upper flange.

[0075] In the present invention, an upper flange is arranged on the core body and close to the head end side of the embedded electrode. The upper flange is made of an aluminum alloy conductor material with a certain structural strength. Furthermore, the upper flange is of an integral structure.

[0076] Such as Figure 2 , an upper flange slot is arranged on the bottom surface (lower side surface) of the upper flange. Preferably, the upper flange slot is an annular slot, and the structural dimensions of the upper flange slot are designed according to the shape and dimensions of the end of the core body so as to be able to be inserted into the end of the core body and have an interference fit with the end of the core body.

[0077] The upper flange is used for clamping and fixing with the core body and also has the functions of passing through the optical fiber lead (fixing the optical fiber) and installing the current optical fiber sensitive ring.

[0078] The main body part of the upper flange is of a disc-shaped structure. An upper flange clamping groove is provided on the lower side surface of the main body part of the upper flange, and an annular groove is provided on the upper side surface of the main body part of the upper flange. This annular groove is used for fixedly installing the current optical fiber sensitive ring.

[0079] The upper flange is installed at the end of the core body to seal the end of the core body and at the same time the terminal post should pass through and be connected to the current-carrying high-voltage conductor to be measured. Therefore, an upper flange assembly hole is provided through the bottom of the upper flange clamping groove. The upper flange assembly hole is a round hole and is used for the equipotential connection between the current-carrying high-voltage conductor to be measured and the embedded electrode.

[0080] In the present invention, an upper flange is provided, and the optical fiber passes through and is led out from the upper flange. A current-carrying end cover is provided on the upper side surface of the upper flange. The current-carrying end cover is made of an aluminum conductive material and current can pass through it.

[0081] Specifically, the current-carrying end cover is of a round cover structure. An isolation insulating ring (made of insulating materials such as epoxy resin, bakelite board, etc.) is provided between the upper flange and the current-carrying end cover. Further, in the present invention, an annular groove is provided at the position of the upper flange for contacting the isolation insulating ring. At the same time, in the present invention, an annular groove is provided at the position of the current-carrying terminal for contacting the isolation insulating ring, and a sealing ring is provided in the annular groove, so as to realize the sealed contact between the current-carrying end cover and the isolation insulating ring and the sealed contact between the upper flange and the isolation insulating ring. Still further, the current-carrying end cover and the upper flange are fixedly connected by bolts, and insulating grains are provided on the bolts, so as to realize the insulated contact between the bolts and the current-carrying end cover.

[0082] In the present invention, a terminal block is provided on the upper flange and / or the current-carrying end cover, which is convenient for the connection between the embedded electrode and the current-carrying high-voltage conductor to be measured.

[0083] 8. Lower flange.

[0084] The lower flange is provided on the tail end side of the core body close to the embedded electrode. The lower flange is made of an aluminum alloy conductor material with a certain structural strength. Further, the lower flange is of an integral structure.

[0085] Such as Figure 2 , an upper flange clamping groove is provided on the top surface (upper side surface) of the lower flange. Preferably, the upper flange clamping groove is an annular groove, and the structural dimensions of the upper flange clamping groove are designed according to the shape and dimensions of the end of the core body, so as to be able to be clamped into the end of the core body and have an interference fit with the end of the core body. The optical fiber passes through and is led out from the lower flange, and the lower flange can fix the optical fiber.

[0086] The central part of the lower flange is of a hole structure, and the inner edge of the hole structure extends towards the center position, but does not cover the arc-shaped groove at the bottom of the core body. This structure can improve the casting strength between the core body and the flange.

[0087] A basin body is provided on the bottom surface of the lower flange. The basin body is an independent structure, and the basin body and the lower flange are fixedly connected by bolts. The bottom surface of the lower flange is a planar structure, and an annular groove is provided at the part of the bottom surface of the lower flange for contacting the basin body. A sealing ring is provided in the annular groove, so as to realize the sealed connection between the lower flange and the basin body.

[0088] The basin body has a mounting table provided at the end facing the embedded electrode. The voltage optical sensor unit is fixedly arranged on the mounting table and is arranged opposite to the end of the embedded electrode along the axial direction of the embedded electrode. The optical fiber passes through the lower flange and is coiled under the mounting table to form an optical fiber coiling coil. A boss structure (mounting table) is provided at the upper part of the center of the basin body, which can improve and optimize the electric field strength of the mounting table, and is beneficial to the voltage sensing unit to sensitively measure the electric field.

[0089] Specifically, the mounting table is a frustum structure, and the mounting table is coaxially arranged with the embedded electrode. At the same time, in the present invention, a basin body circular groove is provided on the bottom surface of the basin body, and the basin body circular groove is coaxially arranged with the embedded electrode, and the optical fiber coiling coil is arranged in the basin body circular groove.

[0090] A lower bottom cover is fixedly connected to the basin body below the optical fiber coiling coil in the present invention. A sealing ring is provided between the lower bottom cover and the basin body, and the lower bottom cover is an insulating cover structure.

[0091] In a specific embodiment of the present invention, the novel 25 kV combined optical current transformer sensing unit provided by the present invention is a novel 25 kV combined optical current transformer sensing component. The novel 25 kV combined optical current transformer sensing unit includes the following structures: a current-carrying end cover, an isolation insulating ring, a current optical fiber sensing ring, a 25 kV optical fiber composite bushing (composed of an embedded electrode and a core), a basin body, a bottom cover, a voltage optical sensing unit, insulating grains, nuts, an upper flange, a silicone rubber umbrella group (silicone rubber umbrella group), a lower flange, optical fibers, a plurality of sealing rings, and a plurality of bolt assemblies. The embedded electrode and the core (epoxy resin) are integrally cast. The two ends of the core are installed with an interference fit on the upper flange and the lower flange. The optical fiber is embedded in a groove on the outer surface of the core in an S shape. The two ends of the optical fiber pass through the openings of the upper flange and the lower flange. On the basis of the above-assembled structure, silicone rubber is cast to manufacture the silicone rubber umbrella group. The upper flange is provided with an annular groove structure, and the current optical fiber sensing ring is installed in the annular groove structure. An isolation insulating ring is provided between the upper flange and the current-carrying end cover. The current-carrying end cover and the isolation insulating ring are installed on the upper flange through bolts. The bolts are insulated from the current-carrying end cover through insulating grains. Both the upper and lower surfaces of the isolation insulating ring are sealed through sealing rings. The embedded electrode is provided with a terminal post, and the terminal post extends out of the upper flange and is fastened through a nut for equipotential connection. The lower flange is installed with a basin body through bolts. The contact surface between the lower flange and the basin body is sealed through at least two layers of sealing rings (the diameters of the two layers of sealing rings are different, so the two layers of sealing rings are sleeved together). The optical fiber passes through the opening at the basin body and reaches the cavity (circular groove of the basin body) at the bottom of the basin body. The upper cavity boss of the basin body is an installation platform, and the voltage optical sensing unit is installed on the installation platform. The bottom end face of the basin body is installed with a bottom cover and sealed with a sealing ring.

[0092] The present invention provides a hole structure on the basin body (on the side wall of the basin body), and the optical fiber passes through this hole structure and is connected to the signal demodulation unit. The demodulation unit emits optical signals to the optical fiber sensing ring and the sensing unit through a light source, and demodulates and calculates the returned optical signals to obtain the current and voltage signals sensed in the optical signals, so as to finally obtain the current and voltage values.

[0093] Specifically, in the present invention, the optical fiber is divided into two parts. One part of the optical fiber is wound outside the epoxy resin core, specifically, it is arranged at the interface between the silicone rubber umbrella group and the core, wound around the core in an S shape, and wound from the bottom end to the top end of the core. There are optical fiber outlets at both the top end and the bottom end (on the top flange and the bottom basin body). The optical fiber at the top end is connected to the optical fiber sensing ring and is responsible for sensing the current signal. The optical fiber at the bottom end passes through the outlet of the basin body and is connected to the signal demodulation unit. The other part of the optical fiber is connected to the voltage optical sensing unit and is responsible for sensing the voltage signal, and then passes through the basin body to the signal demodulation unit. This part of the optical fiber is only in the basin body and has no contact with the core.

[0094] Based on the above structural design, the novel 25 kV combined optical current transformer sensing unit provided by the present invention can simultaneously install a current fiber optic sensing loop and a voltage optical sensing unit, thereby forming a combined structure.

[0095] In addition, the present invention is provided with terminal blocks on both the current-carrying end cover and the upper flange. The current passes through the inside of the current fiber optic sensing loop from the contact surface between the current-carrying end cover and the upper flange and then flows out. The outer rings of the current-carrying end cover and the upper flange are insulated from each other by an isolating insulating ring. The basin has two cavity structures, an upper cavity for installing the voltage optical sensing unit and a bottom cavity for coiling the optical fiber.

[0096] The present invention can give full play to the advantages of the optical current transformer itself. It is a combined current transformer with a more compact overall structure, flexible, safe, and convenient usage, and high integration.

[0097] The optical mutual inductance detection method shows advantages over traditional current transformers in many aspects. For example, the optical current transformer uses a non-invasive sensing and measurement method, achieving complete optoelectronic isolation, and having advantages such as a wide frequency response, a large dynamic range, no magnetic saturation, and being light and easy to install. The present invention realizes the high integration of the current transformer and provides a new solution for the application of optical current transformers in the fields of power systems and high-speed railways.

[0098] The present invention provides a novel 25 kV combined optical current transformer sensing unit, which includes: an embedded electrode that is connected to the same potential as the high-voltage conductor carrying the current to be measured. The embedded electrode is in a columnar structure, and the head end of the embedded electrode is used to be connected to the same potential as the high-voltage conductor carrying the current to be measured, and an electric field can be generated around the embedded electrode; a core body arranged outside the embedded electrode, the core body is an insulating structure, and the tail end of the embedded electrode is located inside the core body; an optical fiber arranged outside the core body along the axial direction of the embedded electrode in a spiral winding manner, and polarized light is propagated by the optical fiber. One end of the optical fiber is an input end connected to the current fiber optic sensing loop, and the other end of the optical fiber is an output end connected to the demodulation unit. The input end and the output end are led outwards relative to the core body. After the optical fiber is arranged on the core body, installation positions can be formed at both ends in the axial direction of the core body, and the installation positions are used to install auxiliary measuring elements. For example, a current fiber optic sensing loop is arranged near the head end of the embedded electrode; a voltage optical sensor unit is arranged near the tail end of the embedded electrode, where the current fiber optic sensing loop and the voltage optical sensor unit are both auxiliary measuring elements.

[0099] In the prior art, it is difficult to combine optical current and voltage transformers due to insulation problems. In the present invention, key technologies such as coiling the optical fiber and the casting method are adopted to solve the insulation problem between the high voltage and the grounding end, and at the same time, the optical signal is led from the high voltage end to the grounding end to realize signal transmission. In addition, the present invention also uses epoxy resin as the manufacturing material of the core body. The core body wraps and embeds the electrode to realize the insulation problem between the high voltage end and the basin body. The optical fiber is wound around the outer surface of the epoxy resin core body to solve the insulation problem of the optical fiber. The silicone rubber umbrella skirt is cast integrally with the epoxy resin core body to solve the external insulation problem. These three parts are the core contents for solving the insulation problem.

[0100] Through the above structural design, compared with the prior art, the advantages of the present invention are as follows:

[0101] 1. The current optical fiber sensitive ring and the voltage optical sensing unit can be installed simultaneously. The whole transformer is of a combined structure with high integration.

[0102] 2. The optical fiber is helically wound around the core body. Both ends of the optical fiber pass through the upper and lower end flanges and are provided with sealing rings for sealing treatment, and the sealing effect is good.

[0103] 3. The core body is integrally cast with epoxy resin, and the optical fiber is helically wound around the outer surface of the core body, so it is not easy to have high voltage breakdown and has excellent insulation performance.

[0104] 4. The present invention realizes a closed and non-contact method (the closed type means that the optical fiber sensitive ring, the voltage sensing unit and the optical fiber are all in a closed space, having excellent dust-proof, waterproof and anti-corrosion performance and strong environmental adaptability. The non-contact type means that there is no contact between the optical fiber sensitive ring and the current-carrying conductor, and there is no contact between the voltage sensing unit and the high voltage end. The current and voltage signals can be measured through a non-contact method), reducing the interference of the external environment, reducing the insulation hidden danger and improving the measurement accuracy.

[0105] 5. Both the current-carrying end cover and the upper end flange are provided with terminal blocks. The current passes through the inside of the current optical fiber sensitive ring from the contact surface between the current-carrying end cover and the upper end flange and flows out (the current flows in from the terminal of the current-carrying end cover, passes through the middle part of the current-carrying end cover through the optical fiber sensitive ring and then flows out from the terminal of the upper end flange). The current optical fiber sensitive ring is arranged in a lying position, reducing the overall height.

[0106] 6. After the embedded electrode and the epoxy resin core are integrally formed, the silicone rubber umbrella group (silicone rubber umbrella group) is cast, which not only ensures the internal insulation (internal insulation refers to the insulation method adopted to prevent the high-voltage part from conducting and breaking down through the internal dielectric and the grounding end. For example, the embedded electrode is wrapped with epoxy resin), but also ensures the external insulation (external insulation refers to the insulation method adopted to prevent the high-voltage part from conducting and breaking down through the external surface of the dielectric and the grounding end. For example, the silicone rubber umbrella group), improving the overall structural strength and insulation strength of the present invention;

[0107] 7. The present invention is small in volume, light in weight, simple and reliable in insulation, high in integration, and good in protection, solving the difficult-to-combine insulation problem of optical current and voltage transformers.

[0108] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A novel 25kV combined optical current transformer sensing unit, characterized in that, it includes: A 25KV optical fiber composite bushing, the 25KV optical fiber composite bushing includes an embedded electrode that is isopotentially connected to the high-voltage conductor with current to be measured, and a core body disposed around the embedded electrode. The core body is an insulating structure, and the tail end of the embedded electrode is located within the core body; Optical fibers wound around the outer side of the core body in an S-shaped helix along the axial direction of the embedded electrode; An upper flange disposed at one end of the 25KV optical fiber composite bushing. One end of the optical fiber is led out from the upper flange, and a current optical fiber sensitive ring is disposed in the upper flange; A lower flange disposed at the other end of the 25KV optical fiber composite bushing. The other end of the optical fiber is led out from the lower flange, and a voltage optical sensing unit is fixedly disposed relative to the lower flange; A ball head structure is provided at the tail end of the embedded electrode. Corresponding to the ball head structure, a concave spherical groove structure is provided at the bottom of the core body to control the thickness of the epoxy resin and air gap between the ball head structure end of the embedded electrode and the boss where the voltage optical sensing unit is located, so that the thickness ratio of the two is appropriate, thereby making the electric field strength distribution more conducive to the measurement of the sensing unit.

2. The novel 25kV combined optical current transformer sensing unit according to claim 1, characterized in that, A spiral core body groove structure is provided on the outer side surface of the core body along the axial direction of the embedded electrode, and the optical fiber is disposed within the core body groove structure.

3. The novel 25kV combined optical current transformer sensing unit according to claim 1, characterized in that, A silicone rubber umbrella skirt is provided on the outer side of the 25KV optical fiber composite bushing, and the optical fiber is disposed between the core body and the silicone rubber umbrella skirt.

4. The novel 25kV combined optical current transformer sensing unit according to claim 1, characterized in that, The bottom surface of the upper flange is provided with an upper flange clamping groove for clamping and fixing with the core body. An upper flange assembly hole is provided through the bottom of the upper flange clamping groove for the isopotential connection between the high-voltage conductor with current to be measured and the embedded electrode. A current-carrying end cover is provided on the upper side surface of the upper flange.

5. The novel 25kV combined optical current transformer sensing unit according to claim 4, characterized in that, The upper flange clamping groove and the core body are in interference fit; An isolation insulating ring is provided between the upper flange and the current-carrying end cover; An annular groove coaxial with the upper flange assembly hole is provided on the upper side surface of the upper flange. The annular groove is located within the isolation insulating ring, and the current optical fiber sensitive ring is disposed within the annular groove.

6. The novel 25kV combined optical current transformer sensing unit according to claim 5, characterized in that, The upper side surface of the lower flange is provided with a lower flange clamping groove for clamping and fixing with the core body, and the optical fiber passes through the lower flange and is led out; A basin body is provided on the bottom surface of the lower end flange. The basin body has a mounting table arranged towards the tail end of the embedded electrode, and the voltage optical sensing unit is arranged on the mounting table, and the voltage optical sensing unit is arranged towards the tail end of the embedded electrode; The optical fiber passes through the lower end flange and is coiled and arranged on the lower side of the mounting table; A lower bottom cover is fixedly connected to the bottom surface of the basin body.

7. The novel 25kV combined optical current transformer sensing unit according to claim 6, characterized in that, The mounting table is of a frustum structure, and the mounting table is coaxially arranged with the embedded electrode; A basin body circular groove is provided on the bottom surface of the basin body, the basin body circular groove is coaxially arranged with the embedded electrode, and the optical fiber coiling coil is arranged in the basin body circular groove.

8. The novel 25kV combined optical current transformer sensing unit according to claim 7, characterized in that, A sealing ring is arranged between the isolation insulating ring, the current-carrying end cover and the upper end flange; A sealing ring is arranged between the lower bottom cover and the basin body; A sealing ring is arranged between the basin body and the lower end flange; A wiring terminal row is arranged on the upper end flange and / or the current-carrying end cover.

9. The novel 25kV combined optical current transformer sensing unit according to claim 3, characterized in that, The silicone rubber umbrella group includes an umbrella group main body in a cylindrical structure, and an annular silicone rubber umbrella is arranged on the outer side surface of the umbrella group main body, and the silicone rubber umbrellas are arranged at intervals along the axial direction of the embedded electrode.

10. The novel 25kV combined optical current transformer sensing unit according to claim 1, characterized in that, The core body is an epoxy resin core body, the core body is a cylindrical structure coaxially arranged with the embedded electrode, and the core body is cast and formed on the outer side of the embedded electrode.

Images