A cable fixing structure for acceptance testing of photovoltaic power station box-type transformer

Abstract

This utility model provides a cable fixing structure for the handover test of a photovoltaic power station transformer substation, belonging to the technical field of cable fixing structures. The cable fixing structure includes: a wedge-shaped metal ring assembly divided into at least three circumferential segments, each segment having a spiral groove on its outer surface; a high-friction flexible pad tightly fitted to the inner circumferential surface of each segment; and an integral elastic steel ring surrounding the outer side of the metal ring assembly, the inner circumferential surface of which has a protruding ridge that engages with the spiral groove. When the elastic steel ring rotates relative to the metal ring assembly, the protruding ridge slides along the spiral groove, driving each wedge-shaped metal ring segment to synchronously contract radially and synchronously generate axial displacement, thus forming a self-tensioning clamp. This solves the problem of loose cable joints and uneven stress during the handover test caused by the inability of traditional fixing structures to adaptively clamp according to changes in cable tension.

Description

Technical Field

[0001] This utility model belongs to the technical field of cable fixing structure. Specifically, it relates to a cable fixing structure for the handover test of a photovoltaic power station transformer box. Background Technology

[0002] The commissioning test of the transformer substation in a photovoltaic power station is a crucial step in verifying the safe grid connection of the step-up transformer, inverter, and supporting cable system. During the test, a large number of high-voltage power cables need to be led from the test equipment to the low-voltage or high-voltage side bushings of the transformer substation, and a series of operations, including wiring, voltage boosting, measurement, voltage reduction, and disconnection, must be completed within a short period. Due to the confined space inside the transformer substation, the significant weight of the cables, and the often drastic temperature differences, wind, sand, and vibrations in the outdoor environment, the cables must be securely fixed to ensure that the joints are not subjected to additional tension, to prevent insulation wear, and to ensure the accuracy of test data and personnel safety. Therefore, the industry commonly uses metal clamps, plastic cable ties, bolt plates, or cable tray suspension to temporarily fix the cables to the transformer substation casing or temporary supports.

[0003] However, these traditional fixing structures revealed many drawbacks at the handover test site. First, bolt clamps need to be tightened one by one with tools such as wrenches, which is labor-intensive and prone to being too loose or too tight due to uneven manual force application; if too loose, the cable will gradually move downwards under its own weight, resulting in uneven stress on the joint, while if too tight, it may damage the cable sheath. Second, once the metal clamps and plastic cable ties are locked, their clamping force cannot be adjusted with changes in cable tension. When the temperature drops suddenly, the material shrinks, causing "over-clamping," and when the temperature rises, "loosening and rebound" occurs, requiring repeated inspections and secondary tightening. Third, most fixing components require pre-drilling holes or welding brackets into the transformer substation casing, which not only damages the anti-corrosion coating and increases the risk of later corrosion, but also makes on-site restoration work cumbersome. Utility Model Content

[0004] In view of this, the present invention provides a cable fixing structure for the handover test of a photovoltaic power station transformer box, which solves the problem that the traditional fixing structure cannot adaptively clamp according to the change of cable tension, resulting in loose cable joints and uneven force during the handover test.

[0005] This utility model is implemented as follows: This utility model provides a cable fixing structure for the handover test of a photovoltaic power station transformer box, comprising: A wedge-shaped metal ring assembly divided into at least three lobes along the circumference, with spiral grooves on the outer surface of each lobe; High-friction flexible pads are placed close to the inner circumferential surface of each petal; An integral elastic steel ring surrounds the outside of the metal ring assembly, and the inner circumferential surface of the elastic steel ring is provided with a protruding ridge that engages with the spiral groove. When the elastic steel ring rotates relative to the metal ring assembly, the convex ridge slides along the spiral groove, driving each wedge-shaped metal ring to synchronously contract radially and synchronously generate axial displacement, so as to form a self-tensioning clamp.

[0006] The technical advantages of the cable fixing structure for the handover test of photovoltaic power station box transformer provided by this utility model are as follows: This clamp organically combines the wedge-shaped metal ring assembly, the high-friction flexible pad and the elastic steel ring, so that the rotating elastic steel ring can simultaneously achieve radial contraction and axial displacement. By utilizing the wedge force amplification principle, the cable's own weight is converted into a continuously increasing clamping force, so that reliable fixing can be maintained without additional fasteners such as bolts and nuts throughout the handover test. This significantly simplifies on-site operation and avoids the risk of loosening caused by uneven tightening.

[0007] Based on the above technical solution, the cable fixing structure for the handover test of the photovoltaic power station transformer box of this utility model can be further improved as follows: The metal ring assembly has its segments evenly spaced in the circumferential direction, with a variable radial gap between adjacent segments. The size of the gap increases or decreases with the rotation direction of the elastic steel ring.

[0008] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the wedge-shaped lobes with equal circumferential intervals and the variable gap design make each lobe of the clamp uniformly stressed and deformed synchronously when it contracts, which not only prevents local stress concentration from damaging the cable sheath, but also ensures that round clamping can be achieved on cables of different diameters, thereby improving versatility and long-term reliability.

[0009] Furthermore, the spiral groove extends continuously from one end of the metal ring assembly to the other end, and its groove depth gradually becomes shallower along the extension direction, so that the convex edge gradually increases the radial clamping force of each wedge-shaped metal ring during the sliding process.

[0010] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the continuous and gradual structure of the spiral groove converts the rotational input into a steadily increasing radial clamping force. The operator only needs to lightly rotate the elastic steel ring to feel the force feedback of "the more you rotate, the tighter it gets", which reduces labor intensity and avoids excessive clamping that could cause cable deformation, thus achieving stepless adjustment of the force value that can be perceived.

[0011] Furthermore, the radial inner surface of the high-friction flexible pad is provided with wavy or sawtooth friction-enhancing textures extending along the axial direction. These textures undergo elastic deformation when compressed radially to increase the contact area with the cable sheath.

[0012] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the wavy or serrated friction-enhancing texture is elastically embedded into the surface of the cable sheath after being compressed, forming multi-line contact rather than loop cutting, which not only significantly improves the longitudinal anti-slip ability, but also disperses local pressure, prevents sheath damage, and allows the clamp to maintain a low creep and highly stable clamping state under vibration or temperature difference conditions.

[0013] Furthermore, the elastic steel ring has outwardly folded edges at both axial ends. When subjected to axial tension, the folded edges tend to tighten radially to further shrink in coordination with the metal ring assembly.

[0014] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the rolled edges at both ends of the elastic steel ring generate an additional radial tightening effect when the cable is under tension, which, combined with the wedging effect of the wedge ring, forms a double self-locking mechanism. Even if there is a sudden impact tension, it can respond instantly, avoid the attenuation of clamping force, and ensure the continuity and accuracy of the handover test data.

[0015] Furthermore, each lobe of the metal ring assembly has an annular limiting shoulder on its outer peripheral surface near both axial ends. The limiting shoulder abuts against the corresponding end face of the elastic steel ring to restrict the axial movement of the elastic steel ring.

[0016] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the abutment structure between the limiting shoulder and the end face of the elastic steel ring not only prevents the axial movement of the steel ring, but also acts as a mechanical stop for the rotation stroke, preventing excessive rotation from causing the parts to separate, improving the integrity and repeatable service life of the device, and reducing the risk of on-site misoperation.

[0017] Furthermore, the outer peripheral surface of the high-friction flexible pad is provided with positioning ribs, and the inner peripheral surface of each lobe of the metal ring assembly is provided with positioning grooves that are complementary in shape to the positioning ribs, so as to prevent the pad from being misaligned during circumferential rotation.

[0018] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the interlocking fit between the positioning rib and the groove ensures that the high friction pad is always circumferentially synchronized with the wedge-shaped petals, eliminating clamping eccentricity or local wear caused by pad slippage, ensuring that the design friction coefficient can still be maintained after long-term operation, and reducing maintenance frequency and spare parts costs.

[0019] Furthermore, the outer circumferential surface of the elastic steel ring is provided with anti-slip knurling or radial ribs arranged at intervals along the circumference to provide gripping friction during rotational operation.

[0020] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the knurling or ribs on the outer surface of the elastic steel ring can provide reliable gripping force in wet, oily or gloved environments, allowing a single person to complete the installation or disassembly by hand without additional tools, which greatly improves the mobility and efficiency of on-site handover testing of photovoltaic power stations.

[0021] Furthermore, the axial end face of the metal ring assembly is provided with a chamfer or rounded transition to guide and protect the cable sheath when the cable is inserted.

[0022] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the chamfer or rounded corner of the end face of the wedge-shaped metal ring plays a guiding role when the cable is inserted, avoiding sharp edges from scratching the sheath, while reducing insertion resistance and realizing a quick assembly experience of "one-click insertion", which is particularly suitable for operation inside the box-type substation with limited space.

[0023] Furthermore, the radial thickness of each wedge-shaped metal ring gradually increases from one end of the axial direction to the other, so as to form a progressive wedge tightening effect towards the cable when the radial contraction occurs, thereby achieving a self-locking effect where the greater the tension, the tighter the clamping.

[0024] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the gradually thickened wedge profile causes the inner surface of the clamp to generate a continuously increasing radial pressure distribution when the cable is under tension, forming a "self-reinforcing" clamping force curve opposite to the direction of tension. Thus, even under long-term operation or extreme conditions such as sudden gusts of wind or earthquakes, it can still maintain the self-locking characteristic of clamping tighter as the tension increases, ensuring the long-term safety and stability of the cable under handover test.

[0025] Compared with existing technologies, the beneficial effects of the cable fixing structure for photovoltaic power station transformer box-type handover tests provided by this utility model are as follows: The self-tensioning wedge-shaped segmented clamp proposed in this utility model, through the synergistic design of the wedge-shaped metal ring assembly, high-friction flexible pad, and elastic steel ring, transforms the traditional "fixed clamping" into "tension-adaptive clamping." When the cable experiences tension due to its own weight or external forces, this tension is transformed by the wedge structure into a continuously increasing radial clamping force, achieving a "tighter and tighter" self-locking, thereby maintaining a constant cable position throughout the entire handover test cycle and avoiding uneven joint stress and insulation damage caused by loosening. Since installation and disassembly can be achieved solely by rotating the elastic steel ring, no bolts, nuts, washers, or other loose parts are required, allowing on-site operators to complete the task by hand, significantly reducing labor intensity and shortening test preparation and completion time. The uniform circumferential arrangement of the wedge-shaped ring segments ensures that the clamping force is evenly distributed along the cable circumference. Combined with the elastic deformation of the high-friction flexible pad, this increases the effective contact area and disperses local compressive stress, preventing sheath indentation and creep damage. The rolled edge at the end of the elastic steel ring generates additional radial tightening under tension, forming a double self-locking mechanism with the wedge-shaped force amplification. This ensures rapid response and stable clamping even under sudden impact loads. Details such as the limiting shoulder, positioning ribs, and chamfered guide further enhance the integration of components and assembly tolerance, preventing component scattering and operational errors. The overall structure is compact and reusable, requiring no openings or welding in the transformer housing, causing zero damage to the anti-corrosion coating. After testing, it can be directly disassembled, restoring the original site condition, thus balancing economy and environmental protection. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is an example diagram of a cable fixing structure used for handover testing of a photovoltaic power station transformer substation. Figure 2 A perspective view of a cable fixing structure used for handover testing of a photovoltaic power station transformer substation; Figure 3 An example diagram of an elastic steel ring for a cable fixing structure used in the handover test of a photovoltaic power station transformer box; The attached diagram lists the components represented by each number as follows: 10. Metal ring assembly; 11. Spiral groove; 12. Limiting shoulder; 20. Elastic steel ring; 21. Raised rib; 22. Rolled edge. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0029] like Figures 1-3 The diagram shown is an example of a cable fixing structure for acceptance testing of a photovoltaic power station transformer substation provided by this utility model, including: A wedge-shaped metal ring assembly 10 is divided into at least three lobes along the circumference, and each lobe has a spiral groove 11 on its outer surface; High-friction flexible pads are placed close to the inner circumferential surface of each petal; An integral elastic steel ring 20 surrounds the outer side of the metal ring assembly 10, and the inner circumferential surface of the elastic steel ring 20 is provided with a protruding rib 21 that engages with the spiral groove 11. When the elastic steel ring 20 rotates relative to the metal ring assembly 10, the protruding rib 21 slides along the spiral groove 11, driving each wedge-shaped metal ring to synchronously contract radially and synchronously generate axial displacement, so as to form a self-tensioning clamp.

[0030] In the above technical solution, the petals of the metal ring assembly 10 are equally spaced in the circumferential direction, and a variable radial gap is formed between adjacent petals. The size of the gap increases or decreases with the rotation direction of the elastic steel ring 20.

[0031] Furthermore, in the above technical solution, the spiral groove 11 extends continuously from one end of the metal ring assembly 10 to the other end, and its groove depth gradually becomes shallower along the extension direction, so that the convex rib 21 gradually increases the radial clamping force of each wedge-shaped metal ring during the sliding process.

[0032] Furthermore, in the above technical solution, the radial inner surface of the high-friction flexible pad is provided with wavy or sawtooth friction-enhancing textures extending along the axial direction. The textures generate elastic deformation when compressed radially to increase the contact area with the cable sheath.

[0033] Furthermore, in the above technical solution, the elastic steel ring 20 has outwardly folded edges 22 at both axial ends. When subjected to axial tension, the edges 22 tend to tighten radially to further shrink in coordination with the metal ring assembly 10.

[0034] Furthermore, in the above technical solution, each of the outer peripheral surfaces of the metal ring assembly 10 is provided with annular limiting shoulders 12 near the two ends of the axial direction. The limiting shoulders 12 abut against the corresponding end faces of the elastic steel ring 20 to restrict the axial movement of the elastic steel ring 20.

[0035] Furthermore, in the above technical solution, the outer peripheral surface of the high-friction flexible pad is provided with positioning ribs, and the inner peripheral surface of each lobe of the metal ring assembly 10 is provided with positioning grooves that are complementary to the shape of the positioning ribs, so as to prevent the pad from being misaligned during circumferential rotation.

[0036] Furthermore, in the above technical solution, the outer circumferential surface of the elastic steel ring 20 is provided with anti-slip knurling or radial ribs arranged at intervals along the circumference to provide gripping friction during rotational operation.

[0037] Furthermore, in the above technical solution, the axial end face of the metal ring assembly 10 is provided with a chamfer or rounded transition to guide and protect the cable sheath when the cable is inserted.

[0038] Furthermore, in the above technical solution, the radial thickness of each wedge-shaped metal ring gradually increases from one end of the axial direction to the other, so as to form a progressive wedge tightening effect towards the cable when the radial contraction occurs, thereby achieving a self-locking effect where the greater the tension, the tighter the clamping.

[0039] First embodiment: The handover test of the transformer substation for a coastal tidal flat photovoltaic power station. The tidal flat foundation is soft and the sea wind is strong. The transformer substation is located on a concrete pile foundation platform. During the test, the high-voltage cable needs to be led from the submarine cable junction box to the low-voltage side of the transformer substation. The entire process involves a large suspended span and significant lateral wind sway, which places extremely high demands on the cable fixation's self-adaptive ability and vibration resistance.

[0040] The clamp is forged from salt spray resistant stainless steel. The wedge-shaped metal ring assembly is divided into three circumferential segments, each with a continuous spiral groove machined on its outer surface. The groove is a single-ended rectangular thread. The high-friction flexible gasket is made of oil-resistant EPDM rubber, with a thickness that gradually changes from the middle to both ends. It fits the inner side of each segment and is vulcanized for fixation. The elastic steel ring is made of integral spring steel, with the rolled edges at both ends turned outward to form a limiting ring. The inner circumferential surface is directly stamped with trapezoidal protrusions that mesh with the spiral grooves, eliminating the need for additional inserts. During installation, first pass the cable through the clamp, then hold the rolled edge of the steel ring with a glove and rotate it clockwise about two turns. The protrusions drive the wedge-shaped segments to contract radially and advance axially until a noticeable increase in resistance is felt, at which point you can stop. To disassemble, simply rotate in the opposite direction to loosen it.

[0041] Sea breezes cause the cable to oscillate periodically, resulting in a wide range of tensile stress variations. The self-tensioning structure converts dynamic load into instantaneously increased radial pressure, always keeping the cable and bushing coaxial; the wedge-shaped lobes are evenly distributed, ensuring uniform circumferential distribution of clamping force and preventing indentations on the sheath; both stainless steel and rubber are salt spray resistant, requiring no maintenance during the test period. No wrenches or bolts are needed on-site, and installation can be completed by a single person on a narrow, high-altitude platform, significantly shortening the test time during tidal windows.

[0042] Second embodiment: The transformer substation underwent handover testing at a photovoltaic power station in a high-altitude desert region. The diurnal temperature range could reach tens of degrees Celsius, the sandy foundation was soft, and the substation was placed on a movable skid-mounted base. The test cables needed to be repeatedly disassembled and reassembled as the skid moved, requiring the clamps to have the ability to quickly and repeatedly tighten and loosen without damaging the cable sheath.

[0043] The wedge-shaped metal ring assembly has been replaced with a six-lobed aluminum alloy extrusion molding, with high-temperature resistant fluororubber strips filling the gaps between the lobes to prevent sand and dust from entering; the spiral groove has been replaced with a double-ended trapezoidal thread, increasing the lead and reducing the rotation angle; the high-friction flexible gasket is made of glass fiber reinforced silicone rubber, with a diamond-shaped grid molded on the surface, the apex of the grid being slightly lower than the root, so that the grid maintains line contact even when shrinking at low temperatures; the elastic steel ring is now made of high-strength beryllium copper strip, with the rolled edges at both ends tapering inwards, and the internal ridges are enhanced with wear resistance through laser cladding of hard particles. During installation, the included simple handle is inserted into the rolled edge hole of the steel ring and rotated about one and a half turns to lock it in place, and rotated half a turn in the opposite direction to loosen it.

[0044] The diurnal temperature variation causes significant daily changes in cable length. The six-lobed wedge structure maintains a rounded and tight fit during thermal expansion and contraction, without any local loosening. The double-ended thread shortens the operating stroke and reduces operating time in high-altitude, windy, and sandy environments. The fluororubber dustproof strip prevents sand particles from entering the meshing surface, avoiding jamming. The high resilience of the beryllium copper steel ring maintains stable torque after repeated disassembly and assembly, meeting the repeated clamping requirements of multiple tests on the same cable and reducing spare parts consumption.

[0045] Specifically, the principle of this invention is as follows: Based on the combined principle of wedge-shaped force amplification and helical transmission, this invention converts axial tension into radial clamping force and achieves self-locking through shape coupling. The clamp body is composed of several wedge-shaped metal rings, each with a continuous helical groove on its outer surface. The helix angle geometrically forms an inclined plane mechanism. After the convex ridge on the inner side of the elastic steel ring is embedded in the groove, the rotational motion of the steel ring relative to the ring is immediately converted into the radial displacement of the ring along the helical surface. Due to the mechanical amplification characteristic of the wedge-shaped inclined plane, which allows for "small displacement input and large force output," only moderate rotation is needed to form radial pressure on the inner side of the ring that is sufficient to overcome the cable's own weight. As the tension on the cable increases, this tension is transmitted to the ring through the static friction between the cable sheath and the high-friction pad, forcing the ring to slide further along the helical inclined plane. The radial pressure increases accordingly, forming a self-reinforcing clamping force proportional to the tension, thus achieving self-locking. The high-friction flexible gasket not only provides a sufficient coefficient of friction but also utilizes its own elasticity to fill the surface irregularities of the cable at a microscopic level, increasing the actual contact area and reducing local stress peaks. The elastic steel ring, while providing rotational drive, can absorb some energy under vibration conditions through its overall elastic energy storage, reducing dynamic slippage between the ring and the cable. Structures such as the rolled edge, limiting shoulder, and positioning ribs eliminate redundant degrees of freedom between parts through geometric constraints, ensuring that the force transmission path always follows the design axis, avoiding off-center loading and wear. Throughout the entire process, there are no other moving parts besides the rotating steel ring; the structure is simple, the force flow is direct, and the energy loss is extremely low, thus enabling it to maintain high-reliability clamping for extended periods without external power or electronic control.

Claims

1. A cable fixing structure for handover testing of a photovoltaic power station transformer substation, characterized in that, include: A wedge-shaped metal ring assembly divided into at least three lobes along the circumference, with spiral grooves on the outer surface of each lobe; High-friction flexible pads are placed close to the inner circumferential surface of each petal; An integral elastic steel ring surrounds the outside of the metal ring assembly, and the inner circumferential surface of the elastic steel ring is provided with a protruding ridge that engages with the spiral groove. When the elastic steel ring rotates relative to the metal ring assembly, the convex ridge slides along the spiral groove, driving each wedge-shaped metal ring to synchronously contract radially and synchronously generate axial displacement, so as to form a self-tensioning clamp.

2. The cable fixing structure for the handover test of a photovoltaic power station transformer according to claim 1, characterized in that, The metal ring assembly has its segments equally spaced in the circumferential direction, and a variable radial gap is formed between adjacent segments. The size of the gap increases or decreases with the rotation direction of the elastic steel ring.

3. The cable fixing structure for the handover test of a photovoltaic power station transformer according to claim 2, characterized in that, The spiral groove extends continuously from one end of the metal ring assembly to the other end, and its groove depth gradually becomes shallower along the extension direction, so that the convex edge gradually increases the radial clamping force of each wedge-shaped metal ring during the sliding process.

4. The cable fixing structure for the handover test of a photovoltaic power station transformer according to claim 3, characterized in that, The high-friction flexible pad has a radially inner surface with a wavy or sawtooth friction-enhancing texture extending along the axial direction. The texture generates elastic deformation when compressed radially to increase the contact area with the cable sheath.

5. The cable fixing structure for the handover test of a photovoltaic power station transformer substation according to claim 4, characterized in that, The elastic steel ring has outwardly folded edges at both axial ends. When subjected to axial tension, the folded edges tend to tighten radially to further shrink in coordination with the metal ring assembly.

6. The cable fixing structure for the handover test of a photovoltaic power station transformer substation according to claim 5, characterized in that, Each lobe of the metal ring assembly has an annular limiting shoulder on its outer peripheral surface near both ends of the axial direction. The limiting shoulder abuts against the corresponding end face of the elastic steel ring to restrict the axial movement of the elastic steel ring.

7. The cable fixing structure for the handover test of a photovoltaic power station transformer substation according to claim 6, characterized in that, The outer circumferential surface of the high-friction flexible pad is provided with positioning ribs, and the inner circumferential surface of each lobe of the metal ring assembly is provided with positioning grooves that are complementary in shape to the positioning ribs, so as to prevent the pad from being misaligned during circumferential rotation.

8. The cable fixing structure for the handover test of a photovoltaic power station transformer according to claim 7, characterized in that, The outer circumferential surface of the elastic steel ring is provided with anti-slip knurling or radial ribs arranged at intervals along the circumference to provide grip friction during rotation.

9. A cable fixing structure for handover testing of a photovoltaic power station transformer according to claim 8, characterized in that, The axial end face of the metal ring assembly is provided with a chamfer or rounded transition to guide and protect the cable sheath when the cable is inserted.

10. A cable fixing structure for handover testing of a photovoltaic power station transformer according to claim 9, characterized in that, The radial thickness of each wedge-shaped metal ring gradually increases from one end of the axial direction to the other, so as to form a progressive wedging effect towards the cable when the radial contraction occurs, thereby achieving a self-locking effect where the greater the tension, the tighter the clamping.

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