A transformer body composite vibration isolation support and a transformer body vibration isolation design method

Abstract

The present invention discloses a composite vibration isolation support for a transformer body and a vibration isolation design method for the transformer body. The composite vibration isolation support includes an annular lower pressing plate installed at the bottom of the transformer oil tank, and an annular upper pressing plate fixed above the annular lower pressing plate. The annular upper pressing plate is provided with a flange portion that is inserted downward into the inner hole of the annular lower pressing plate. An annular metal rubber elastic element is arranged between the flange portion and the bottom of the annular lower pressing plate. An annular laminated rubber vibration isolation element is placed on the annular metal rubber elastic element. The annular laminated rubber vibration isolation element is supported on the bottom beam of the transformer body support. A locking bolt passes through the inner holes of the annular metal rubber elastic element and the annular laminated rubber vibration isolation element and is connected to the bottom beam. The gaps between the annular metal rubber elastic element and the annular upper pressing plate and between the annular laminated rubber vibration isolation element are filled with a sealing filling material. The present invention can better adapt to the oil environment inside the oil tank where the transformer body is located, and has good vibration isolation and energy dissipation and vibration reduction effects.

Description

Technical Field

[0001] The present invention belongs to the technical field of transformers, and particularly relates to the technology of vibration reduction and noise reduction for transformers. Background Art

[0002] With the rapid progress of urbanization and the rapid development of power grid construction in China, the vibration and noise caused by equipment such as transformers and reactors in substations of various voltage levels have become prominent problems in power grid construction and operation. The noise of transformer equipment is generated by the vibration of its internal iron core and winding coils under the action of voltage and current, and is transmitted to the air through the box structure and propagated outward. Among them, the reason for the vibration of the winding coil is that after the equipment applies a load, the electromagnetic force generated by the current therein interacts at different parts of the annular coil, causing the coil itself to generate periodic expansion and contraction; the reason for the vibration of the iron core is the magnetostrictive vibration generated by itself in the electromagnetic field and the action exerted on it by the electromagnetic force. Since both the electromagnetic force and the magnetostrictive effect are closely related to the periodic change of the electromagnetic field, the vibration and noise characteristics of transformer equipment are directly related to the frequency of the applied alternating current.

[0003] Many feasible methods have been proposed abroad to reduce the vibration and noise of transformers. For example, by improving the iron core structure, reducing the magnetostriction of silicon steel sheets, and reducing the rated working magnetic density of the iron core, etc., good effects of vibration reduction and noise reduction have been achieved. In addition, noise reduction measures such as sound insulation, sound absorption, and noise elimination have also been adopted in European and American countries, and relatively remarkable effects have been obtained. China has achieved certain results in the treatment of substation noise. Transformer manufacturers, power grid companies, and related universities and research institutions have carried out a large number of research and applications on vibration and noise control technologies for transformer equipment, and there is little difference from foreign levels in the research of vibration and acoustics theory and the formulation of relevant standards. In particular, many scientific and technological achievements, practical technical measures and solutions with remarkable effects have been obtained in the acoustic vibration analysis, sound insulation, noise elimination, plane layout optimization and overall substation noise reduction technology of substation sound source equipment. Based on the noise control standards for power transmission and transformation projects promulgated by international organizations such as IEC and referring to the noise level control indicators of developed foreign countries, the GB / T 22075-2008 Audible Noise Control Standard for High Voltage DC Converter Stations has been compiled, forming reasonable equipment manufacturing standards and noise test and detection methods.

[0004] At present, methods such as reducing the noise of the transformer equipment body itself, taking noise reduction measures in the propagation path, optimizing the substation layout plan, and adopting auxiliary noise reduction measures have been taken at home and abroad for substation noise reduction. Vibration and noise reduction of the core body is the most direct and effective way to control the vibration and noise of the transformer. To reduce the noise of the transformer body, first, it is necessary to optimize the structure and manufacturing process of the core body and the fuel tank, etc., and select high-permeability high-quality silicon steel sheets; second, it is necessary to start from the propagation path of noise and vibration, and take measures to cut off the propagation path and consume or block the energy of vibration and noise. However, it is not cost-effective to control the vibration and noise of the transformer only from the selection of core and winding materials, manufacturing process, and structure optimization. It is necessary to start from the sound and vibration propagation path of the transformer, and auxiliary vibration and noise reduction measures such as core body vibration isolation can be adopted to reduce the transmission of core body vibration to the fuel tank wall, foundation, and adjacent structures.

[0005] The core body of the transformer often floats on the positioning pins at the bottom of the fuel tank through the clamping parts, or rubber gaskets are set at the bottom of the clamping parts. Most of the vibration energy of the transformer core body winding and core will be transmitted to the tank wall through the box body at the bottom of the fuel tank and radiate noise outward. As a new type of elastic material, metal rubber not only has good elasticity and damping characteristics, but also has remarkable characteristics such as convenient processing and forming, aging resistance, and strong adaptability. In recent years, the application of metal rubber components in the field of vibration isolation and damping in complex operating environments has become more and more extensive. However, in engineering, the compression deformation stiffness and damping of metal rubber are mostly used for vibration reduction. For equipment with a small mass, it is difficult to give full play to the mechanical and mechanical properties such as high damping and high elasticity of metal rubber by using compression deformation. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a composite vibration isolation support for the transformer core body installed inside the transformer fuel tank, which effectively solves the technical problems of the complex vibration characteristics and many main frequencies of the transformer core body.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions: A composite vibration isolation support for the transformer core body is installed below the transformer core body, including an annular lower pressing plate installed at the bottom of the transformer fuel tank, and an annular upper pressing plate fixed above the annular lower pressing plate. The annular upper pressing plate is provided with a flange portion that is inserted downward into the inner hole of the annular lower pressing plate. An annular metal rubber elastic element is arranged between the flange portion and the bottom of the annular lower pressing plate. An annular laminated rubber vibration isolation element is placed on the annular metal rubber elastic element. The annular laminated rubber vibration isolation element is supported on the bottom beam of the transformer core body support. A locking bolt passes through the inner holes of the annular metal rubber elastic element and the annular laminated rubber vibration isolation element and is connected to the bottom beam. The outer diameter of the annular laminated rubber vibration isolation element is smaller than the inner hole diameter of the annular upper pressing plate. The gaps between the annular metal rubber elastic element, the annular upper pressing plate, and the annular laminated rubber vibration isolation element are filled with sealing and filling materials.

[0008] Preferably, the annular upper pressing plate and the annular lower pressing plate are fixed into an integral body by connecting screws distributed at intervals in the circumferential direction.

[0009] Preferably, a rubber sealing ring is arranged between the annular cross sections where the annular upper pressing plate and the annular lower pressing plate are in contact.

[0010] Preferably, a sealing ring is arranged at the part where the locking bolt is connected to the bottom beam.

[0011] Preferably, the annular lower pressing plate is of a stepped structure, with a small bottom diameter and a large upper diameter. The bottom is installed in the positioning hole at the bottom of the transformer oil tank, and a stepped surface for positioning the annular metal rubber elastic element is arranged at the upper part of the inner hole of the annular lower pressing plate.

[0012] Preferably, thin steel sheets are arranged on the upper side or / and the lower side of the annular metal rubber elastic element.

[0013] Preferably, thin steel gaskets are arranged on the upper side or / and the lower side of the annular laminated rubber vibration isolation element.

[0014] The present invention also provides a vibration isolation design method for the transformer body.

[0015] First, according to the vibration isolation mechanical model of the transformer body, establish the parameter equation of the vibration isolation layer of the transformer body:

[0016] For the transformer body, the external load excitation F(t) is written in the following form:

[0017]

[0018] According to D'Alembert's principle, the motion equation of the single-degree-of-freedom vibration isolation system of the transformer body is obtained as:

[0019]

[0020] In the formula: M is the total mass of the body and the clamping parts, in kg, K eq , C eq are respectively the equivalent stiffness and equivalent damping of the vibration isolation layer;

[0021] The equivalent stiffness K eq and equivalent damping C eq of the series spring system composed of several different types of vibration isolation elements are respectively:

[0022]

[0023]

[0024] The force transmitted to the bottom plate of the oil tank is F d , and by solving the motion equation (1), the relationship between F d and F is obtained:

[0025]

[0026] Where: T is the response dynamic magnification factor or transmissibility; R is the corresponding vibration isolation efficiency; ω i is a specific frequency of the exciting force; ω eq is the equivalent natural frequency of the vibration isolation layer of the equipment body; λ is the ratio of the excitation frequency to the frequency of the vibration isolation layer of the equipment body; ξ is the equivalent damping ratio of the vibration isolation layer;

[0027] By solving formula (4), the relationship curve between the transmissibility T and the damping ratio ξ and the frequency ratio λ is obtained;

[0028] Then, determine the parameters of the vibration isolation layer of the transformer body:

[0029] On the premise that the target transmissibility T and the damping ratio ξ are both known, the target control excitation frequency ω i and the frequency ratio λ of the vibration isolation layer are obtained through formula (4), and the vertical design stiffness k of the vibration isolation layer is obtained from the mass M of the equipment body i , that is:

[0030]

[0031] It can be seen from formula (5) that when the target control excitation frequency ω i and λ are known, the vertical stiffness k of the vibration isolation layer i is proportional to the mass M of the equipment body; the stiffness k of the vibration isolation layer i is proportional to the square of the target control excitation frequency ω i , so when designing the vibration isolation of the transformer body, 100 Hz is used as the control frequency of the vibration isolation layer; in addition, the vertical stiffness k of the vibration isolation layer i is inversely proportional to the square of the frequency ratio λ. Therefore, theoretically, the larger the frequency ratio λ, the smaller the required vertical design stiffness of the vibration isolation layer. However, considering the weight of the equipment body and the long-term operation safety, the frequency ratio λ of the vibration isolation layer is taken as 6 - 8;

[0032] After obtaining the vertical design stiffness of the vibration isolation layer of the equipment body, determine the position and quantity of the vibration isolation supports according to the mass of the equipment body and the connection method between the clamping parts of the transformer body and the bottom of the lower oil tank.

[0033] The technical solution adopted by the present invention has the following beneficial effects:

[0034] The annular metal rubber elastic element and the annular laminated rubber vibration isolation element can be swapped according to the design of the control frequency; moreover, the annular metal rubber elastic element can be replaced with elements of different thicknesses, and the annular laminated rubber vibration isolation element can be replaced with elements of different diameters and heights. If the height of the replaced annular laminated rubber vibration isolation element decreases, annular thin steel gaskets with the same diameter can be set on the upper side or the lower side of the annular laminated rubber vibration isolation element.

[0035] Therefore, it can effectively solve the technical problems of the complex vibration characteristics and multiple main frequencies of the transformer body; it can give full play to the bending stiffness and high damping characteristics of the metal rubber elastic element, be applicable to the vibration isolation of the transformer and reactor bodies of different voltage levels, can better adapt to the oil environment inside the oil tank where the transformer body is located, and has good vibration isolation and energy dissipation and vibration reduction effects.

[0036] The specific technical solution and its beneficial effects of the present invention will be described in detail in the following specific embodiments in conjunction with the accompanying drawings. Description of the Drawings

[0037] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments:

[0038] Figure 1 It is a schematic structural diagram of a composite vibration isolation support for a transformer body installed inside a transformer oil tank according to the present invention;

[0039] Figure 2 It is a front view of a typical vibration isolation support layout scheme for a 110 kV power transformer body;

[0040] Figure 3 It is a top view of a typical vibration isolation support layout scheme for a 110 kV power transformer body;

[0041] In the figure: A - vibration isolation support; 1 - annular metal rubber elastic element; 2 - annular laminated rubber vibration isolation element; 3 - cavity; 4 - annular lower pressing plate; 5 - annular upper pressing plate; 6 - locking bolt; 7 - connecting screw; 8 - bottom beam; 9 - bottom of the transformer oil tank; 10 - sealing filler material; 11 - transformer body;

[0042] Figure 4 It is a schematic diagram of simplifying the vibration isolation mechanical model of the transformer body into a single - mass model;

[0043] Figure 5 It is a relationship curve between the transmissibility T, the damping ratio ξ, and the frequency ratio λ. Specific Embodiments

[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The description of at least one exemplary embodiment is actually only illustrative and in no way restrictive of the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0045] Those skilled in the art can understand that, without conflict, the features in the following embodiments and implementation manners can be combined with each other.

[0046] The transformer body refers to the iron core and winding assembled into one body inside the oil tank through clamping parts. The iron core is stacked by thousands of ultra-thin silicon steel sheets, and the winding is a coil wound around the iron core.

[0047] The silicon steel sheets and coils in the iron core and winding generate electromagnetic vibrations under no-load and load conditions, thus causing noise. Generally, when the transformer is under no-load, the noise signal caused by the winding vibration is very small, and the noise of the transformer is mainly caused by the magnetostriction of the iron core; when under load, since the magnetic flux in the iron core is very small and the vibration of the iron core can be ignored, the noise of the transformer is mainly caused by the vibration of the winding under the action of the magnetic field force. Under the normal operation state of the transformer, the vibration of the transformer body is composed of the superposition of the iron core vibration caused by the magnetostriction of the silicon steel sheets and the winding vibration caused by the magnetic field force. Under the action of the alternating magnetic field, the silicon steel sheets undergo magnetostriction, causing the iron core to vibrate periodically with the change of the excitation frequency. Since the change period of magnetostriction is 1 / 2 of the power frequency voltage, the iron core noise caused by magnetostriction has a fundamental frequency of 2 times the power frequency voltage. Due to the strong non-linear characteristics of the iron core magnetostriction and the different lengths of the magnetic flux paths along the inner and outer frames of the iron core, in addition to the fundamental frequency, the iron core vibration and noise also contain even multiples of the power frequency voltage frequency and other high-order resonance frequencies.

[0048] The current in the transformer body coil and the leakage magnetic field interact with each other, causing electromagnetic force to be generated on the winding wire. The leakage magnetic field and the current in the winding act on each other, causing axial and radial electrodynamic forces on the winding. Research shows that the winding of a large-capacity power transformer can generate an axial electrodynamic force of 1 kN to 20 kN under the action of the leakage magnetic field. The vibration causes the vibration of the transformer oil, which is transmitted to the iron core clamping parts through contact, causing metal impact and making the whole iron core vibrate. Since the leakage magnetic flux is alternating, according to electromagnetic theory, an alternating electromagnetic attraction force will be generated between the magnetic steel parts with air gaps. If the connections of these parts are unreliable, metal impact will occur, thus generating noise.

[0049] Since the electromagnetic forces on the transformer iron core and winding are mainly transmitted to the clamping parts that restrain the iron core and winding through insulating cardboard, the vibration of the transformer body and the clamping parts is transmitted to the oil tank through the insulating oil medium and the bottom or top fixing devices, causing the vibration of the tank wall. There are mainly two propagation paths for the vibration of the transformer body to be transmitted to the tank wall. The first propagation path is that the vibration of the transformer body is transmitted to the transformer insulating oil through solid-liquid coupling, causing the vibration of the insulating oil medium. When the vibration energy wave is transmitted to the tank wall, it is transmitted to the tank wall through the way of liquid-solid coupling, causing the vibration of the tank wall; the second propagation path is that the vibration of the transformer body is directly transmitted to the bottom plate and the top cover plate of the oil tank through the connecting devices between the clamping parts and the bottom or top of the tank, and then transmitted to the wall plate through the bottom plate and the top cover plate.

[0050] At present, in engineering, the compression deformation stiffness and damping of metal rubber are mostly used for vibration reduction. For equipment with a small mass, it is difficult to give full play to the mechanical properties such as high damping and high elasticity of metal rubber by using compression deformation. Therefore, aiming at the technical problems of complex vibration sources, wide frequency bands, multiple main frequencies, and complex operating environments during the operation of the transformer body, the present invention combines the structure and vibration characteristics of the transformer body and designs a high-damping laminated rubber bearing and a metal rubber composite vibration isolation bearing with adjustable elastic elements and designable stiffness and damping parameters.

[0051] Embodiment 1

[0052] Reference Figures 1 to 3 As shown, a composite vibration isolation bearing A for the transformer body is installed below the transformer body 11 and includes an annular lower pressing plate 4 installed at the bottom of the transformer oil tank and an annular upper pressing plate 5 fixed above the annular lower pressing plate. The annular upper pressing plate 4 is provided with a flange portion that is inserted downward into the inner hole of the annular lower pressing plate. An annular metal rubber elastic element 1 is arranged between the flange portion and the bottom of the annular lower pressing plate. An annular laminated rubber vibration isolation element 2 is placed on the annular metal rubber elastic element 1. The annular laminated rubber vibration isolation element 2 is supported on the bottom beam 8 of the transformer body support. A locking bolt 6 passes through the inner holes of the annular metal rubber elastic element 1 and the annular laminated rubber vibration isolation element 2 and is connected to the bottom beam 8.

[0053] In this embodiment, the annular lower pressing plate has a stepped structure with a small bottom diameter and a large upper diameter, and the bottom is installed in the positioning hole of the transformer oil tank bottom 9. It not only plays the role of bearing vertical loads but also has a limiting function to prevent the displacement of the vibration isolation bearing under loads such as vibration. Further, a stepped surface for positioning the annular metal rubber elastic element is provided in the upper part of the inner hole of the annular lower pressing plate, and a cavity 3 is formed in the lower part of the inner hole of the annular lower pressing plate.

[0054] Among them, the outer diameter of the annular laminated rubber vibration isolation element 2 is smaller than the inner hole diameter of the annular upper pressing plate. The gaps between the annular metal rubber elastic element 1, the annular upper pressing plate 5, and the annular laminated rubber vibration isolation element 2 are filled with a sealing filler 10. The sealing filler 10 plays a sealing role to prevent transformer oil from leaking into the cavity 3.

[0055] The thickness and diameter of the annular metal rubber elastic element 1 are determined by the main frequency of the transformer body to be controlled. The mechanical model of metal rubber can be equivalent to a bending beam model, and the bending stiffness of the metal rubber element can be fitted according to the test results for its calculation method. The stiffness and damping of the annular laminated rubber elastic element 2 are determined by the vibration source frequency to be controlled.

[0056] Among them, the annular upper pressing plate 5 and the annular lower pressing plate 4 are fixed into one body by connecting screws 7 distributed at intervals in the circumferential direction. The annular upper pressing plate 5 and the annular lower pressing plate 4 are provided with the same number of threaded holes corresponding to each other in the circumferential direction and are matched with the connecting screws.

[0057] Since the vibration isolation support is in the transformer oil tank environment for a long time, in order to prevent transformer oil from penetrating into the annular lower pressing plate through the connection part between the annular upper pressing plate and the annular lower pressing plate, a rubber sealing ring is arranged between the annular cross-sections where the annular upper pressing plate and the annular lower pressing plate are in contact. In order to prevent transformer oil from penetrating into the cavity 3 through the locking bolt, a sealing ring is arranged at the part where the locking bolt is connected to the bottom beam.

[0058] The above-mentioned annular metal rubber elastic element 1 and annular laminated rubber vibration isolation element 2 can be exchanged according to the design of the control frequency. The annular metal rubber elastic element 1 can be replaced with elements of different thicknesses, and the annular laminated rubber vibration isolation element 2 can be replaced with elements of different diameters and heights. It can effectively solve the technical problems of complex vibration characteristics and more main frequencies of the transformer body; it can give full play to the bending stiffness and high damping characteristics of the metal rubber elastic element, is suitable for vibration isolation of the transformer body and reactor body of different voltage levels, can better adapt to the oil environment inside the oil tank where the transformer body is located, and has good vibration isolation and energy dissipation and vibration reduction effects.

[0059] If the gap of the annular metal rubber elastic element 1 placed between the annular lower pressing plate 4 and the annular upper pressing plate 5 cannot be filled with the selected elastic element, thin steel sheets with the same inner and outer diameters can be set on the upper side or / and the lower side of the annular metal rubber elastic element to fill it.

[0060] If the height of the replaced annular laminated rubber vibration isolation element 2 decreases, annular perforated thin steel gaskets with the same inner and outer diameters can be set on the upper side or / and the lower side of the annular laminated rubber vibration isolation element.

[0061] Figure 2 and Figure 3 It is a typical layout scheme of the vibration isolation support for the transformer body of a 110 kV power transformer. The rated capacity of the transformer is 315000 kVA, the weight of the transformer body is 34000 kg, 6 vibration isolation supports are arranged at the bottom of the lower oil tank, the diameter of the vibration isolation element is 10 cm, and the surface pressure P A = 7.07 MPa. The vertical compression stiffness of the double-layer vibration isolation element is designed and selected according to the vibration frequencies of 100 Hz and 200 Hz of the transformer body, and the comprehensive isolation efficiency of the transformer body exceeds 96%.

[0062] Embodiment 2

[0063] The present invention also provides a transformer body vibration isolation design method using the above-mentioned transformer body composite vibration isolation support.

[0064] First, according to the vibration isolation mechanical model of the transformer body, establish the parameter equation of the vibration isolation layer of the transformer body.

[0065] The vibration isolation of the transformer body is composed of different types of vibration isolation devices between the bottom beam of the body support and the bottom plate of the fuel tank to form a vibration isolation layer. The vibration isolation mechanical model of the transformer body can be simplified as a single Figure 4 -mass model as shown. Assume that the combined excitation force of the transformer body is F. Since the excitation forces of the body and the winding can be simplified as a harmonic load composed of a 100 Hz and a series of resonance frequencies, that is, for the transformer body, the external load excitation F(t) can be written in the following form:

[0066]

[0067] According to D'Alembert's principle, we can obtain Figure 4 The motion equation of the single-degree-of-freedom vibration isolation system of the transformer body shown is:

[0068]

[0069] Where: M is the total mass of the body and clamping parts, kg, K eq , C eq are the equivalent stiffness and equivalent damping of the vibration isolation layer respectively.

[0070] Since the transformer body mainly has multiple vibration frequency spectrum curves with obvious line spectra such as 100 Hz, 200 Hz... during operation, the vibration isolation layer design can consider designing the vibration isolation layer and vibration isolation devices with 2 - 3 low-order frequencies as the target, and connecting elastic elements with different stiffnesses in series to form a vibration isolation device. The equivalent stiffness K eq and equivalent damping C eq of the series spring system composed of several different types of vibration isolation elements are respectively:

[0071]

[0072]

[0073] The force transmitted to the bottom plate of the fuel tank is F d , and by solving the motion equation (1), the relationship between F d and F can be obtained:

[0074]

[0075] Where: T is the response dynamic amplification factor or transmissibility; R is the corresponding vibration isolation efficiency; ω i is a specific frequency of the excitation force; ω eqis the equivalent natural frequency of the vibration isolation layer of the transformer body; λ is the ratio of the excitation frequency to the frequency of the vibration isolation layer of the transformer body; ξ is the equivalent damping ratio of the vibration isolation layer. By solving Equation (4), the relationship curve between the transmissibility T, the damping ratio ξ, and the frequency ratio λ can be obtained as shown in Figure 5 shown below.

[0076] Finally, determine the parameters of the vibration isolation layer of the transformer body.

[0077] From Figure 5 it can be seen that to achieve a good vibration isolation effect for the transformer body, the frequency ratio λ must be greater than In the vibration isolation region, the larger the frequency ratio λ, the better the vibration isolation effect. Therefore, the vibration isolation layer must have a lower natural frequency ω eq . To ensure the vibration isolation effect, the frequency ratio of the transformer body vibration isolation should ensure that λ ≥ 6. Near the resonance frequency, the damping ratio has a significant shock absorption effect. When the damping ratio doubles, the dynamic magnification factor will be nearly halved; far from the resonance frequency, the damping of the structural system still has a certain shock absorption effect, but it is not as obvious as that near the resonance frequency. Therefore, the damping of the vibration isolation layer is not the larger the better, and it is more appropriate to take 10-20%.

[0078] According to Figure 4 the single-mass vibration isolation theoretical model of the transformer body shown below, on the premise that the target transmissibility T and the damping ratio ξ are both known, the target control excitation frequency ω i and the frequency ratio λ of the vibration isolation layer can be obtained through Equation (4). From the mass M of the transformer body, the vertical design stiffness k of the vibration isolation layer can be obtained i , that is:[[]]

[0079]

[0080] From Equation (5), it can be seen that when the target control excitation frequency ω i and λ are known, the vertical stiffness k of the vibration isolation layer i is proportional to the mass M of the transformer body; the stiffness k of the vibration isolation layer i is proportional to the square of the target control excitation frequency ω i . Therefore, when designing the vibration isolation of the transformer body, 100 Hz can be used as the control frequency of the vibration isolation layer, and the designed stiffness of the vibration isolation layer has better vibration isolation efficiency for other higher-order resonance frequencies. In addition, the vertical stiffness k of the vibration isolation layer i is inversely proportional to the square of the frequency ratio λ. Therefore, theoretically, the larger the frequency ratio λ, the smaller the required vertical design stiffness of the vibration isolation layer. However, considering the weight of the transformer body and the long-term operation safety, it is appropriate to take the frequency ratio λ of the vibration isolation layer as 6-8, and the designed vibration isolation efficiency exceeds 96%, and the vibration isolation effect is significant.

[0081] After obtaining the vertical design stiffness of the body vibration isolation layer, the position and quantity of vibration isolation supports can be determined according to the body mass and the connection mode between the clamping parts of the transformer body and the bottom of the lower oil tank. According to the bearing capacity of the vibration isolation device, the design principle of the quantity of vibration isolators can be controlled by the surface pressure P of the effective bearing area A of the vibration isolator. Generally, it is more appropriate that P A ≤ 8 MPa. A As described above, it is only the specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes but is not limited to the content described in the above specific implementation mode. Any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

[0082] As described above, it is only the specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes but is not limited to the content described in the above specific implementation mode. Any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims

1. A transformer body composite vibration isolation support, which is installed under the transformer body, and is characterized in that: It includes an annular lower pressing plate installed at the bottom of the transformer oil tank and an annular upper pressing plate fixed above the annular lower pressing plate. The annular upper pressing plate is provided with a flange portion that is inserted downward into the inner hole of the annular lower pressing plate. An annular metal rubber elastic element is arranged between the flange portion and the bottom of the annular lower pressing plate. An annular laminated rubber vibration isolation element is placed on the annular metal rubber elastic element. The annular laminated rubber vibration isolation element is supported on the bottom beam of the transformer body support. A locking bolt passes through the inner holes of the annular metal rubber elastic element and the annular laminated rubber vibration isolation element and is connected to the bottom beam. The outer diameter of the annular laminated rubber vibration isolation element is smaller than the inner hole diameter of the annular upper pressing plate. The gaps between the annular metal rubber elastic element, the annular upper pressing plate, and the annular laminated rubber vibration isolation element are filled with a sealing filling material. The annular lower pressing plate is of a stepped structure with a small bottom diameter and a large upper diameter. The bottom is installed in the positioning hole at the bottom of the transformer oil tank. A stepped surface for positioning the annular metal rubber elastic element is provided at the upper part of the inner hole of the annular lower pressing plate. Thin steel sheets are arranged on the upper side or / and the lower side of the annular metal rubber elastic element.

2. The composite vibration isolation support for the transformer body according to claim 1, wherein: The annular upper pressing plate and the annular lower pressing plate are fixed together by connecting screws that are circumferentially spaced apart.

3. The composite vibration isolation support for the transformer body according to claim 1, characterized in that: A rubber sealing ring is arranged between the annular cross-sections where the annular upper pressing plate and the annular lower pressing plate are in contact.

4. The composite vibration isolation support for the transformer body according to claim 1, wherein: A sealing ring is arranged at the part where the locking bolt is connected to the bottom beam.

5. The composite vibration isolation support for the transformer body according to claim 1, wherein: Thin steel gaskets are arranged on the upper side or / and the lower side of the annular laminated rubber vibration isolation element.

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