Tap switch oil chamber oil flow velocity detection sensing system and working method thereof

Abstract

The invention relates to a tap switch oil chamber oil flow velocity detection sensing system and a working method thereof. The system comprises a cable, a distributed optical fiber vibration sensing system and a plurality of spindle-shaped structural bodies. The plurality of fusiform structural bodies are tightly and sequentially nested outside the cable, and the distance between the adjacent structural bodies meets the requirement of one or more spatial resolutions; when the flow velocity equipment works, the distributed optical fiber vibration sensing system demodulates and analyzes the phase of transmission light in the optical fiber at each nesting point, and realizes real-time monitoring of the oil flow velocity according to the corresponding relationship between the phase change and the flow velocity. The oil flow state data of the oil chamber can be collected for a long time when the tap switch is switched, the collected data is high in objectivity, the real-time flow speed can be truly obtained, and real-time monitoring of the state of the tap switch is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of state detection, and in particular to a sensor system for detecting oil flow velocity in an oil chamber of a tap changer and a working method thereof. Background Art

[0002] The converter transformer connects the AC power grid and the converter valve hall, and is the "hub" of DC power transmission. It realizes electrical isolation, power exchange, voltage matching and on-load regulation of AC and DC systems through electromagnetic induction. The on-load tap changer is located inside the converter transformer. It accurately adjusts the converter transformer voltage by switching the voltage regulating coil between different voltage terminals, thereby stably transmitting DC power. When the tap changer gear is switched, multiple mechanical actions of 6 to 8 actuators must be completed in sequence within 100 milliseconds. The operating conditions are complex, the electrical stress of the tap changer switching is severe, and long-term reliable switching is difficult. Due to the rapid increase in oil temperature during the switching process of the tap changer, the oil flow moves. If a part accidentally falls in and is driven by the oil flow, it may cause problems such as prototype burning accidents, which brings huge challenges to the operation and maintenance of DC power transmission. Therefore, it is necessary to closely monitor the oil flow velocity in the tap changer oil chamber.

[0003] However, the existing methods for measuring oil flow velocity, including rotor flowmeters and laser Doppler flowmeters, have many fatal problems. For example, the traditional rotor flowmeter has the disadvantages of high and unstable starting flow velocity, large size, inconvenient use and carrying, etc., and will destroy the natural flow state during flow measurement, thus affecting the measurement accuracy. The laser Doppler flowmeter is difficult to guarantee the measurement accuracy because the suspended matter in the oil will affect the propagation path of the laser. In addition, the laser Doppler flowmeter also has problems such as bulky equipment, high cost, and the need for skilled operators. Since distributed fiber optic sensing technology has the advantages of strong anti-electromagnetic interference ability, simple equipment, and high sensitivity, it is of great significance to use distributed fiber optic sensing technology to monitor the oil flow in the oil chamber of the tap changer in real time. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a tap switch oil chamber oil flow velocity detection sensor system, which can collect oil chamber oil flow status data for a long time when the tap switch is switched. The collected data is highly objective and can truly obtain the real-time flow velocity, which is conducive to real-time monitoring of the tap switch status.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a tap changer oil chamber oil flow velocity detection sensor system, comprising a cable, a distributed optical fiber vibration sensor system, and n spindle-shaped structures, where n is an even number greater than 2;

[0007] The cable consists of an outer sheath, armored steel wire, inner sheath, steel tube and strain-sensing optical fiber, and is used to establish a transmission link between underwater signals and above-water demodulation equipment;

[0008] Nesting n spindle-shaped structures in sequence outside the cable to ensure that the n spindle-shaped structures and the cable do not rotate relative to each other, and the distance L between the n adjacent spindle-shaped structures is set to meet one or more spatial resolution requirements; the n spindle-shaped structures are used to convert the flow velocity information of the oil flow into the torque information of the cable, and then into the phase change information of the optical fiber transmission light in the cable, so as to facilitate the transmission and processing of the signal;

[0009] The distributed optical fiber vibration sensing system is connected to the upper end of the cable and is used to receive and process the phase change information of the light transmitted in the optical fiber to determine the oil flow velocity at the oil level where the cable is currently located.

[0010] Furthermore, the spindle-shaped structure is made of polyolefin elastomer (POE), whose density is slightly lower than that of transformer oil. The equivalent density of the monitoring device can be adjusted by controlling the number of nested spindle-shaped structures and the spacing between adjacent structures, thereby measuring the oil flow velocity at different depths.

[0011] Furthermore, the n spindle-shaped structures are all tightly embedded in the cable with their thick ends being perpendicular to the cable and not rotating relative to the cable; in addition, the structures are arranged at equal intervals on the left and right, and the central symmetry axes of all the spindle-shaped structures are located in the same plane.

[0012] Furthermore, the parts of the spindle-shaped structure located on both sides of the cable have large differences in length and thickness, so that the extended area of ​​the longer and thinner end is twice the extended area of ​​the thicker and shorter end.

[0013] Furthermore, a heavy weight is placed inside the thick end of the spindle-shaped structure without affecting the electric field distribution, so that the center of gravity of the spindle-shaped structure is located at the port of the thick end, thereby ensuring that the central axis of the structure is always perpendicular to the oil plane in a calm state.

[0014] Furthermore, the system structure can convert the oil flow velocity information into the torque information of the cable, and further convert it into the phase change information of the light transmitted in the cable optical fiber. By demodulating these phase signals, the current oil flow velocity can be obtained.

[0015] In a second aspect, the present invention provides a working method of a tap changer oil chamber oil flow velocity detection sensor system, the working method comprising the following steps:

[0016] S1, measure the transformer oil depth at the cable working point and select the required depth to be measured.

[0017] S2, according to step S1, the number of spindle-shaped structures required to be nested on the cable and the calculation formula for the arrangement spacing are as follows:

[0018]

[0019] Wherein, n is the number of spindle-shaped structures, r is the test radius, and h is the accuracy coefficient.

[0020] S3, the upper end of the cable is connected to the distributed optical fiber vibration sensing system, in which the optical fiber is connected with a flange; the lower end of the cable is placed in the oil chamber, waiting for it to float to the depth to be measured until it is stable.

[0021] S4, real-time demodulation of the data sent back by the strain measuring optical fiber in the cable, and obtaining the oil flow velocity at the current measurement depth according to the relationship between the flow velocity and the phase change of the light transmitted in the optical fiber of the cable. The calculation formula is as follows:

[0022]

[0023] Among them, θ end is the terminal phase, θ is the initial phase, z is the propagation distance, ω is the frequency, and v is the fluid velocity.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] (1) The spindle-shaped structure embedded in the cable is made of POE elastomer, which has high elasticity, high strength physical and mechanical properties as well as excellent anti-aging and corrosion resistance. Compared with traditional flow rate detection devices, it has a longer service life and maintenance cycle in the long-term working environment of high corrosion and strong impact such as real-time monitoring of oil flow velocity in the oil chamber of the tap changer.

[0026] (2) The density of the cable used is greater than the density of the transformer oil, and the density of the spindle-shaped structure is slightly less than the density of the transformer oil. The monitoring device can adjust the overall equivalent density by controlling the number of nested spindle-shaped structures and the spacing between adjacent structures, thereby measuring the flow rate of oil flows of different qualities and depths, greatly improving the speed measurement range of the device.

[0027] (3) The thick ends of the n spindle-shaped structures embedded in the cable are connected to the cable, and the n spindle-shaped structures are arranged at equal intervals. The thin ends of the spindle-shaped structures are distributed on the left and right relative to the cable, and the central symmetry axes of all the structures are located on the same plane, thereby ensuring the balance of weight on both sides of the cable and thus not causing additional deformation to the cable itself. In addition, the periodic structure strengthens the force of the oil flow on the cable, which is beneficial to the later demodulation of the phase change information of the light transmitted in the optical fiber in the cable.

[0028] (4) Compared with the existing oil flow velocity detection method, the oil flow velocity detection sensor technology system of the tap changer oil chamber of the present invention uses optical fiber as the signal transmission medium, which has good anti-electromagnetic interference capability; the entire system consists of only two major parts: cables and signal demodulation and processing equipment, and the device is simple and easy to operate; in addition, after the cable is successfully laid, long-term real-time monitoring of the oil flow velocity can be achieved without repeated operations by personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the use status of the oil flow velocity detection sensor system in the oil chamber of the tap changer.

[0030] Figure 2 is a cross-sectional view of a cable used in an embodiment of the present invention.

[0031] Figure 3 Schematic diagram of a spindle-shaped structure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The present invention will now be described in further detail with reference to the accompanying drawings.

[0033] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back", etc. cited in the invention are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments in their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0034] Example 1: See Figure 1 , Figure 1 It is a schematic diagram of the structure of the oil flow velocity detection sensor technology of the tap switch oil chamber of the embodiment of the present invention. The oil flow velocity detection sensor system of the tap switch oil chamber includes a cable 20, a distributed optical fiber vibration sensor system and n spindle-shaped structures 30, n is an even number greater than 2, and n=8 in Example 1; the n spindle-shaped structures are closely nested outside the cable in sequence to ensure that there is no relative rotation with the cable, and the distance L between adjacent structures meets one or more spatial resolution requirements; the distributed optical fiber vibration sensor system is connected to the upper end of the cable, and is used to receive and process and analyze the phase change information of the transmitted light in the optical fiber, so as to determine the oil flow velocity at the oil level of the transformer where the current cable is located, and the signal demodulation processing module can be placed outside the tap switch oil chamber, which is convenient for the operation and maintenance of the operation and maintenance personnel and the real-time monitoring of the oil flow velocity.

[0035] Figure 2It is a cross-sectional view of the cable used in the present invention. The cable includes an outer sheath 21, an armored steel wire 23, an inner sheath 25, a steel pipe 27 and a strain measuring optical fiber 29. The outer sheath 21 is located outside the inner sheath 25. The gap between the concentric circles formed by the outer sheath 21 and the inner sheath 25 is uniformly filled with a number of armored steel wires 23. The strain measuring optical fiber 29 is inserted into a steel pipe 27 made of stainless steel, and the gap is filled with fiber paste 22. The filled steel pipe 27 is set in the inner sheath 25, and the gap is filled with fillers and then twisted into a cable. The cable is used to protect the optical fiber structure and to establish a transmission link between underwater signals and surface demodulation equipment. The upper end is connected to a signal demodulation processing module, and the lower end is used to receive oil flow velocity information.

[0036] Figure 3 Schematic diagram of a spindle-shaped structure. As a preferred example, the spindle-shaped structure is made of POE material with a density of 0.9 g / cm 3 , with high elasticity, high strength physical and mechanical properties and excellent anti-aging and corrosion resistance under the premise of low density. For example, a single spindle-shaped structure weighs 400g under the condition of internal counterweight, with an axial height of 40cm, a transverse length of 10cm at the thick end, and a thickness of 6cm at the center. The hole for nesting is located 4cm from the thick end at the axial center. Since the outer diameter of the cable used in the oil flow velocity detection sensor system of the tap changer oil chamber is 3cm, the size of the hole for nesting is slightly larger than 3cm, and 3.1-3.2cm is the best. After nesting to the corresponding position, a waterproof adhesive should be used to fix it so that it fits tightly to the outside of the cable to ensure that there is no relative rotation between the cable and the cable, so as to avoid the weakening of the oil flow impact effect and reduce the measurement accuracy of the system.

[0037] In order to obtain different pressures on both sides of the cable so as to achieve the purpose of converting the oil flow velocity information into the torque information of the cable, the parts of the spindle-shaped structure located on both sides of the cable have large differences in length and thickness, so that the extension area S1 of the long and thin end is twice the extension area S2 of the thick and short end. Since the oil flow pressure within the axial height of 30cm of the spindle-shaped structure can be approximately regarded as isobaric, and S1 and S2 are located in the same plane and S1=2*S2, according to the pressure formula P=F / S, it can be known that the pressure F1 on the extension surface of the long and thin end is twice the pressure F2 on the extension surface of the thick and short end. Due to the pressure difference between the upper and lower sides of the cable, the cable will twist at the position of each nested spindle-shaped structure, generating a certain torque, causing the optical fiber in the cable to deform, thereby changing the phase of the transmitted light in the optical fiber. When the oil flow velocity changes, the pressure P changes. When the force-bearing areas on both sides remain unchanged, the pressure p and the pressure F are linearly related. Therefore, there is a certain linear mapping relationship between the oil flow velocity and the phase of the light transmitted in the optical fiber. The current oil flow velocity is obtained by demodulating the phase signal.

[0038] As one preferred example, a metal weight of 150g is placed inside the spindle-shaped structure. The metal used is Hastelloy, which is resistant to acid corrosion, to avoid the imbalance of the mass of each structure due to oil penetration corrosion. In addition, the metal weights are placed at the same position of the thick end of each spindle-shaped structure, so that the overall center of gravity of the spindle-shaped structure is located at the port of the thick end, thereby ensuring that the oil flow impact is always perpendicular to the extension surface of the spindle-shaped structure in a calm state, defining the reference point for the measurement of different oil flow velocities, and improving the measurement accuracy of the oil flow velocity detection sensor system of the tap changer oil chamber.

[0039] As a preferred example, the thin ends of n spindle-shaped structures are arranged at equal intervals on both sides of the cable, one on the left and one on the right, and the central symmetry axes of all spindle-shaped structures are located in the same plane, so as to ensure the balance of weight on both sides of the cable and that the cable itself does not produce additional strain when impacted by oil flow, thereby eliminating the influence of cable bending deformation on measurement accuracy. In addition, the periodic structure strengthens the force of the oil flow on the cable, which is conducive to enhancing the phase change of the transmitted light in the optical fiber in the cable, and is convenient for subsequent demodulation processing.

[0040] Embodiment 2: A working method of a tap changer oil chamber oil flow velocity detection sensing technology, using the tap changer oil chamber oil flow velocity detection sensing system defined in Embodiment 1, the working method comprising the following steps:

[0041] S1, measure the oil depth at the cable working point and select the required depth to be measured, taking the oil flow rate in the oil chamber when a certain type of tap changer produced by Shanghai Huaming is switched as an example.

[0042] S2, according to step S1, calculate the number and arrangement spacing of the spindle-shaped structures required to be nested on the cable; the oil-water density at 0.5m below the oil field can be measured in advance to be about 1.05g / cm 3 For example, choose a length of 1m and a cross-sectional area of ​​28.27cm 2 The equivalent density of a cable of a certain type with a mass of 2kg / m is 0.87g / cm for the POE material used in the spindle-shaped structure and the internal metal weight. 3 , the volume of a single structure is about 2000cm 3 , it can be deduced that the equivalent density of the entire velocity measuring device when 10 spindle-shaped structures are nested is 1.052 g / cm 3 Therefore, it is only necessary to nest 10 spindle-shaped structures at an interval of 0.08m on the cable to achieve stable positioning of the speed measuring device at a depth of 0.5 under the oil.

[0043] S3, the upper end of the cable is connected to the distributed fiber optic vibration sensing system, in which the optical fiber is connected with a flange; the lower end of the cable is placed in oil and water, waiting for it to float to the depth to be measured until it is stable; for example, the distributed fiber optic vibration sensing system can use the φ-OTDR system, the wavelength of the laser used is 1550nm, the pulse width is 30ns, the pump current is 450mA, and the spatial resolution is 0.01m.

[0044] S4, real-time demodulation of the data sent back by the strain measuring optical fiber in the cable, and acquisition of the oil flow velocity at the current measurement depth based on the relationship between the flow velocity and the phase change of the light transmitted in the optical fiber of the cable. The measured flow velocity is 0.05 m / s.

[0045] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A tap changer oil chamber oil flow velocity detection sensor system, characterized in that: It includes a cable, a distributed optical fiber vibration sensing system, and n spindle-shaped structures, where n is an even number greater than 2; The cable is used to establish a transmission link between underwater signals and above-water demodulation equipment; Nesting n spindle-shaped structures in sequence outside the cable to ensure that the n spindle-shaped structures and the cable do not rotate relative to each other, and the distance L between the n adjacent spindle-shaped structures is set to meet one or more spatial resolution requirements; the n spindle-shaped structures are used to convert the flow velocity information of the oil flow into the torque information of the cable, and then into the phase change information of the optical fiber transmission light in the cable; The distributed optical fiber vibration sensing system is connected to the upper end of the cable and is used to receive, process and analyze the phase change information of the light transmitted in the optical fiber to determine the oil flow velocity at the oil layer where the cable is currently located.

2. A tap changer oil chamber oil flow velocity detection sensor system according to claim 1, characterized in that: The spindle-shaped structure is made of polyolefin elastomer POE, and its density is slightly lower than that of transformer oil.

3. The oil flow velocity detection sensor system for the tap changer oil chamber according to claim 1 is characterized in that: The n spindle-shaped structures have their thick ends tightly nested in the cable, perpendicular to the cable and without relative rotation, and the thin ends of the spindle-shaped structures are arranged at equal intervals on the left and right relative to the cable, and the central symmetry axes of all the spindle-shaped structures are located in the same plane.

4. The oil flow velocity detection sensor system for the oil chamber of a tap changer according to claim 1, characterized in that: The parts of the spindle-shaped structure located on both sides of the cable have differences in length and thickness, so that the extension area of ​​the long and thin end is twice the extension area of ​​the thick and short end.

5. The oil flow velocity detection sensor system for the oil chamber of a tap changer according to claim 1, characterized in that: A heavy weight is placed inside the thick end of the spindle-shaped structure without affecting the electric field distribution, so that the center of gravity of the spindle-shaped structure is located at the port of the thick end, thereby ensuring that the central axis of the structure is always perpendicular to the oil plane in a calm state.

6. A working method of the oil flow velocity detection sensor system of the tap changer oil chamber according to any one of claims 1 to 5, characterized in that: The working method The following steps are involved: S1, measure the transformer oil depth at the cable working place and select the required depth to be measured; S2, according to step S1, calculate the number and arrangement spacing of the spindle-shaped structures required to be nested on the cable, and the calculation formula is as follows: Wherein, n is the number of spindle-shaped structures, r is the test radius, and h is the accuracy coefficient. S3, the upper end of the cable is connected to the distributed optical fiber vibration sensing system, where the optical fiber is connected with a flange; the lower end of the cable is placed in the oil chamber and waits for it to float to the depth to be measured until it is stable; S4, real-time demodulation of the data sent back by the strain measuring optical fiber in the cable, and obtaining the oil flow velocity at the current measurement depth according to the relationship between the flow velocity and the phase change of the light transmitted in the optical fiber of the cable. The calculation formula is as follows: Among them, θ end is the terminal phase, θ is the initial phase, z is the propagation distance, ω is the frequency, and v is the fluid velocity.

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