Method for repairing offshore photovoltaic upper supporting structure

Abstract

The invention provides a method for repairing an offshore photovoltaic upper supporting structure, and relates to the field of offshore photovoltaic technologies. The method comprises the steps that a self-elevating operation platform is positioned to the position under a to-be-repaired net rack unit, and the self-elevating operation platform is provided with a synchronous jacking system and a pile leg leveling system; a pile leg of the operation platform extends into the seabed, the pile leg is fixed to the seabed, meanwhile, the pile leg lifts the operation platform to be separated from the sea level, and the operation platform is leveled through a pile leg leveling system; under the control of the synchronous jacking system, the net rack units are lifted stage by stage, so that the net rack units are separated from the pile foundation structure; damaged parts of the net rack units are replaced in the critical unloading state; and a pressure-displacement double-closed-loop control strategy is adopted for carrying out graded unloading on the net rack unit, so that the repaired net rack unit falls back to the pile foundation structure. According to the method, the damaged net rack unit can be reliably repaired, and the situation that the net rack unit cannot be used due to irreversible deformation in the repairing process is avoided.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of offshore photovoltaic technology, in particular to a method for repairing an offshore photovoltaic upper support structure. BACKGROUND

[0002] Photovoltaic is a power generation system that converts solar radiation energy into electrical energy by using the photovoltaic effect of semiconductor materials. Photovoltaic is a clean, safe and renewable energy source, and therefore has good application prospects.

[0003] At present, most photovoltaic power generation systems are arranged on land. However, due to the limited space on land and the influence of buildings or plants, the arrangement space of photovoltaic is limited. Therefore, considering the efficiency of receiving solar energy and the arrangement space of photovoltaic, the sea surface becomes a better choice for photovoltaic arrangement. For offshore photovoltaic projects, the construction location belongs to a typical marine atmospheric corrosion environment. The upper support structure is easily damaged in the marine environment due to high humidity. The overall replacement method for repairing the upper support structure has a large economic cost and maintenance cost. Therefore, the local repair method for the upper support structure is the preferred method.

[0004] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present disclosure, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0005] Therefore, a method for repairing an offshore photovoltaic upper support structure is provided. The method can effectively repair the grid unit and avoid damaging the original structure of the grid unit, and avoid irreversible deformation of the grid unit during the repair process.

[0006] Other characteristics and advantages of the present disclosure will become apparent from the following detailed description, or will be learned by practice of the present disclosure.

[0007] According to one aspect of the present disclosure, a method for repairing an offshore photovoltaic upper support structure is provided. The upper support structure includes connected grid units and a pile foundation structure for supporting the grid units, and the grid units are used to support photovoltaic modules. The method comprises the following steps:

[0008] Step S1, positioning a self-elevating work platform directly below the grid unit to be repaired, wherein the self-elevating work platform is equipped with a synchronous jacking system and a pile leg leveling system;

[0009] Step S2, the pile legs of the work platform are extended to the seabed, the pile legs are fixed to the seabed, and the pile legs lift the work platform out of the sea level, and the work platform is leveled by the pile leg leveling system;

[0010] Step S3, the net rack unit is lifted in stages under the control of the synchronous jacking system, so that the net rack unit is separated from the pile foundation structure;

[0011] Step S4, replacing the damaged components of the net rack unit in a critical unloading state;

[0012] Step S5, using a pressure-displacement double closed-loop control strategy to stage unload the net rack unit, so that the repaired net rack unit falls back to the pile foundation structure.

[0013] In an exemplary embodiment of the present disclosure, in step S4, replacing the damaged components of the net rack unit in a critical unloading state comprises:

[0014] When the net rack unit is separated from the pile foundation structure to a preset distance, the jacking of the net rack unit is paused;

[0015] The damaged part of the net rack unit is installed with a pre-tensioned replacement component.

[0016] In an exemplary embodiment of the present disclosure, the damaged part of the net rack unit is installed with a pre-tensioned replacement component, comprising:

[0017] The damaged component at the damaged part of the net rack unit is removed, and the damaged component is lowered to the work platform by a sling;

[0018] A new component of the same specification is installed, the new component is a pre-tensioned replacement component, one end of the new component is fixed to a bolt ball, and the other end of the new component is suspended by a sling;

[0019] The net rack unit is jacked up again to move the net rack unit to an installation position;

[0020] The end of the new component suspended is connected to the bolt ball.

[0021] In an exemplary embodiment of the present disclosure, the critical unloading state comprises:

[0022] The axial force of the target rod member decreases to 15% to 30% of the initial value, the displacement difference between adjacent bolt balls is ≥1.5mm and ≤3m, the torque attenuation of the bolt ball connected to the target rod member is ≥40%, and the target rod member is a damaged component to be replaced.

[0023] In an exemplary embodiment of the present disclosure, the method further comprises:

[0024] The local rigidity compensation device is started in a critical unloading state to form temporary support for the damaged part of the space truss unit;

[0025] The local rigidity compensation device comprises an inflatable carbon fiber reinforced elastomer pad, and the pad is filled with a magneto-rheological fluid in the inside, and the compression modulus of the pad can be adjusted in real time by changing the magnetic field intensity.

[0026] In an exemplary embodiment of the present disclosure, in step S5, a pressure-displacement double closed loop control strategy is adopted to perform staged unloading on the space truss unit, including:

[0027] The space truss unit is subjected to pressure unloading by starting a pressure ring through a hydraulic jack, and the oil pressure fluctuation of the hydraulic jack is maintained to be ≤±2%;

[0028] The space truss unit is subjected to position adjustment by starting a displacement ring through a variable gain PID controller, wherein the gain coefficient of the controller is Wherein, ΔS is the displacement difference of adjacent jacking points, and α = 0.8-1.2.

[0029] In an exemplary embodiment of the present disclosure, the synchronous jacking system comprises:

[0030] The jacking support has an adjustable height range of 10m-25m;

[0031] The hydraulic jacking jack has a stroke ≥500mm;

[0032] The jacking link rod has a universal joint structure; the distributed hydraulic pump station; the PLC control console with a variable gain PID controller;

[0033] The PLC control console is used to adjust the hydraulic pressure provided by the distributed hydraulic pump station in real time according to the jacking state of the space truss unit, so as to control the jacking distance and jacking force of the space truss unit by the hydraulic jacking jack.

[0034] In an exemplary embodiment of the present disclosure, before the space truss unit is jacked, it further comprises:

[0035] The laser-induced breakdown spectroscopy detection is performed on the damaged component, including:

[0036] The surface of the damaged component is ablated using a pulse laser;

[0037] The Fe / Cr element intensity ratio in the plasma emission spectrum is analyzed;

[0038] Determine the damage degree of the damaged component according to the proportion of each element, wherein when Cr / Fe≤0.18, it is determined as serious damage.

[0039] In an exemplary embodiment of the present disclosure, after replacing the damaged component of the grid unit in the critical unloading state, further comprising: performing dynamic frequency matching debugging;

[0040] Performing dynamic frequency matching debugging, comprising:

[0041] Excite the repaired grid unit and collect vibration signals;

[0042] Extract the first three order natural frequencies f1, f2 and f3 of the vibration signals;

[0043] Adjust the pre-tightening force of the new component until ∣(f n -f) / f∣≤0.5% is satisfied; wherein n=1, 2, 3, fn is the natural frequency of the new component, and f is the natural frequency of the original component before replacement.

[0044] In an exemplary embodiment of the present disclosure, before step S3, further comprising:

[0045] Analyze and calculate the layout of the jacking points distributed in the grid unit to make the stress distribution of the grid unit uniform.

[0046] In an exemplary embodiment of the present disclosure, analyzing and calculating the layout of the jacking points distributed in the grid unit, comprising:

[0047] Using finite element analysis to analyze the layout of the jacking points of the grid unit; wherein the finite element analysis parameters at least include sea wave load spectrum, wind speed distribution, and fatigue curve of the grid unit.

[0048] In an exemplary embodiment of the present disclosure, the pile leg leveling system comprises a seabed negative pressure adsorption module, which is installed at the bottom of each pile leg; wherein the adsorption force of the seabed negative pressure adsorption module is ≥200kN / m2.

[0049] The offshore photovoltaic upper support structure repairing method provided by the present disclosure can be used for repairing the local damage of the offshore grid unit, and the grid unit does not need to be replaced as a whole, thereby reducing the maintenance cost; the method controls the staged lifting of the grid unit through the synchronous jacking system, so that the grid unit is separated from the pile foundation structure, and the irreversible deformation of the grid unit during the lifting process can be ensured, and the service life and support reliability of the grid structure after the repairing can be ensured; the pressure-displacement double closed loop control strategy is used to stage unload the grid unit after the repairing of the grid unit, so that the secondary damage of the grid unit during the falling process can be avoided, and the reliability of the repairing is improved; in addition, the method uses the self-elevating work platform, the platform can improve the support stability during the repairing process, and the tilting or instability of the grid unit during the repairing process is avoided, so that the reliability of the repairing process of the grid unit is improved.

[0050] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and are not limiting to the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0051] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and serve to explain the principles of the present disclosure. It is readily apparent to one of ordinary skill in the art that the accompanying drawings are merely illustrative of some embodiments of the present disclosure and that additional embodiments of the present disclosure can be obtained from these drawings without paying creative labor.

[0052] Figure 1 A flow chart of the offshore photovoltaic upper support structure repairing method in an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0053] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations may, however, be implemented in many different forms and should not be construed as limited to the implementations set forth herein; rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example implementations to those skilled in the art. Like reference numerals refer to like elements throughout the description. Moreover, the figures can not be to scale and some features can be exaggerated to illustrate aspects of the implementations.

[0054] Although relative terms are used in this specification, such as "upper", "lower", to describe one component's relationship to another component of the icon, these terms are used herein solely for convenience and are not to be construed as limiting the icon's device to a particular orientation. It is to be understood that if the icon's device were to be turned over such that the "upper" component would then be a "lower" component, the described orientation would still apply. When a structure is "on" another structure, it can mean that the structure is formed integrally with the other structure, or that the structure is "directly" on the other structure, or that the structure is "indirectly" on the other structure by being on one or more other structures.

[0055] The terms "a", "an", "the", "said", and "at least one" are used to refer to one or more elements / components / etc.; the terms "comprise", "comprising", and "having" are used to mean that other elements / components / etc. can be included in addition to the listed elements / components / etc.; the terms "first", "second", and "third", etc. are used only as labels, and do not limit the number of objects to which the terms refer.

[0056] In the related art, the offshore photovoltaic system can include a photovoltaic assembly and an upper support structure, wherein the upper support structure includes a grid unit and a pile foundation structure, and the photovoltaic assembly can be arranged on the grid unit. For the special geographical environment of the sea, it has many adverse environmental factors such as waves, ocean currents, sea ice, sea wind, snow load, high corrosion, etc., and the upper support structure is easy to be damaged by the marine environment, especially for the grid unit, which is relatively large in size, and after damage occurs in some parts, it is easy to have an adverse effect on the overall support strength.

[0057] Due to the complex structure of the grid unit, the damaged grid unit is replaced by the whole replacement method, which has high economic cost and large workload, and the local repair method faces the influence of the complex marine environment and needs to consider the overall deformation and structure layout of the grid unit, and the conventional land grid unit maintenance method cannot be applied to the offshore photovoltaic system.

[0058] Based on this, the disclosure embodiment provides a repairing method for an offshore photovoltaic upper support structure, as shown in the figure, the method comprises steps S1-S5. Figure 1 As shown in the figure, the method comprises steps S1-S5.

[0059] In step S1, the jack-up work platform is positioned directly below the grid unit to be repaired, and the jack-up work platform is equipped with a synchronous jacking system and a pile leg leveling system;

[0060] In step S2, the pile leg of the work platform is inserted into the seabed, the pile leg is fixed to the seabed, and the pile leg lifts the work platform out of the sea level, and the work platform is leveled by the pile leg leveling system;

[0061] Step S3, lifting the net rack unit in stages under the control of a synchronous jacking system to make the net rack unit separate from the pile foundation structure;

[0062] Step S4, replacing the damaged components of the net rack unit under a critical unloading state;

[0063] Step S5, using a pressure-displacement double closed-loop control strategy to unload the net rack unit in stages to make the repaired net rack unit fall back to the pile foundation structure.

[0064] The repairing method of the offshore photovoltaic upper support structure provided by the present disclosure can be used for repairing the local damage of the net rack unit on the sea, without the need to replace the net rack unit as a whole, thereby reducing the maintenance cost. The method can lift the net rack unit in stages under the control of a synchronous jacking system to make the net rack unit separate from the pile foundation structure, so that irreversible deformation of the net rack unit can be avoided during the lifting process, and the service life and support reliability of the net rack structure after repair can be ensured. The method can unload the net rack unit in stages using a pressure-displacement double closed-loop control strategy after repairing the net rack unit, so that secondary damage of the net rack unit can be avoided during the falling back process, thereby improving the reliability of the repair. In addition, the method uses a self-elevating work platform, which can improve the support stability during the repair process and avoid tilting or instability of the net rack unit during the repair process, thereby improving the reliability of the repair process of the net rack unit.

[0065] In the present disclosure, the upper support structure includes a connected net rack unit and a pile foundation structure, the pile foundation structure is used to support the net rack unit, and the net rack unit is used to support photovoltaic components. The net rack unit can have oppositely arranged first and second surfaces, the first surface being located between the second surface and the sea level, and the first surface of the net rack unit can be connected to one end of the pile foundation structure, and the other end of the pile foundation structure is fixed to the seabed, so that the pile foundation structure supports the net rack unit. The net rack unit can be composed of a plurality of single-bay trusses, and the plurality of single-bay trusses can be connected by a plurality of web members, diagonal members, etc., and the adjacent members can be connected by bolt balls. The shape of the net rack unit can be a cuboid or a similar cuboid, and the surface far from the sea level is a support surface for providing support force for the photovoltaic components.

[0066] In the present disclosure, the first face and the second face in the grid unit can be parallel or substantially parallel to each other, and the first face is located between the sea level and the second face. Since the photovoltaic module needs to be suitable for the direction of the sea sun to improve the solar energy absorption rate and utilization rate, the grid unit usually has a certain angle with the sea level, and the angle between the grid unit and the sea level provided by the present disclosure can be a preset angle a, which can be 10°-20°, for example, the preset angle a can be 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19° or 20°, etc. Further, in order to improve the solar energy absorption rate, while taking into account the support strength and stability of the grid unit to the photovoltaic module, the angle between the grid unit and the sea level can be 15°.

[0067] The steps of the repairing method of the offshore photovoltaic upper support structure provided by the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings:

[0068] In the embodiments provided by the present disclosure, in step S1, the self-elevating work platform is positioned directly below the grid unit to be repaired, and the self-elevating work platform is equipped with a synchronous jacking system and a pile leg leveling system.

[0069] The damage of the grid unit can include the breakage of the connecting taper head between the rod and the bolt ball, or the corrosion breakage of the rod, or the pulling out of the rod from the bolt ball, etc. The repairing method provided by the present disclosure is applicable to any of the above damage states. It should be noted that the repairing method provided by the present disclosure can include a method of reconnecting the damaged parts and their connecting parts in addition to replacing the damaged parts, for example, welding the replaced parts and the bolt ball, etc., which can be understood as within the protection scope of the present disclosure.

[0070] The self-elevating work platform is positioned directly below the grid unit to be repaired, which can be achieved by loading the work platform on the work ship and driving it through the channel between adjacent grid units to the position directly below the grid unit to be repaired. After the work platform is positioned directly below the grid unit to be repaired, the work ship can be removed.

[0071] The self-elevating work platform includes a plurality of pile legs, which can support and fix the work platform on the seabed.

[0072] The self-elevating working platform is equipped with a synchronous jacking system, which can include a jacking support, a hydraulic jacking jack, a jacking connecting rod, a distributed hydraulic pump station, and a PLC control console. The jacking connecting rod has a universal joint structure, which can adjust the angle and displacement of the jacking support to ensure the effective relative position relationship between the jacking support and the grid unit. The PLC control console has a variable gain PID controller, which is used to adjust the hydraulic pressure provided by the distributed hydraulic pump station in real time according to the jacking state of the grid unit, to control the jacking distance and jacking force of the hydraulic jacking jack for the grid unit, and to improve the reliability of the synchronous jacking system for jacking the grid unit.

[0073] The jacking support needs to be verified for load before jacking the grid unit, to ensure that the load of the jacking support can meet the support needs of the grid unit. In addition, sensors can be arranged in each component in the synchronous jacking system to measure and feed back the system in real time, and the system is adjusted in real time according to the feedback structure to ensure that the jacking stress or jacking displacement and other parameters meet the jacking needs, so as to avoid irreversible deformation of the grid unit caused by jacking.

[0074] In some embodiments, the self-elevating working platform is also equipped with a six-degree-of-freedom parallel posture adjusting mechanism, which can be arranged on the top of the platform. When the working platform jacks the grid unit, the angle and position of the working platform can be adjusted in real time through the six-degree-of-freedom parallel posture adjusting mechanism, to further improve the reliability of the working platform for jacking the grid unit. The displacement resolution of the six-degree-of-freedom parallel posture adjusting mechanism can be 0.1mm, and the maximum compensation speed can be 1m / s.

[0075] The self-elevating working platform is equipped with a pile leg leveling system, which includes a seabed negative pressure adsorption module installed at the bottom of each pile leg. One seabed negative pressure adsorption module can be arranged on each pile leg to ensure the effective fixation of each pile leg on the seabed and avoid displacement of the working platform during operation, which can cause failure of the grid unit repair; or one seabed negative pressure adsorption module can be arranged on multiple pile legs to provide adsorption force for multiple pile legs through one seabed negative pressure adsorption module, to improve the fixation balance of the pile legs.

[0076] In some embodiments, in order to improve the fixation stability of the pile legs, the adsorption force of the seabed negative pressure adsorption module is ≥200kN / m 2 .

[0077] In the embodiments provided in the present disclosure, in step S2, the pile legs of the working platform are inserted into the seabed, the pile legs are fixed to the seabed, and the pile legs lift the working platform to separate from the sea level, and the working platform is leveled by the pile leg leveling system.

[0078] In order to avoid the influence of marine environment on the work platform during the work, and to reduce the work accuracy and reliability, after the pile legs of the work platform are fixed on the seabed, the pile legs can push the work platform to be separated from the sea level, on the one hand, the work personnel can operate on the platform, on the other hand, the marine environment can be prevented from affecting the work accuracy of the work platform, and the work reliability and stability are further improved.

[0079] In some embodiments, in order to ensure the stability of the work platform, the distance between the work platform and the sea level can be 3m-10m.

[0080] In order to facilitate the transportation of the work platform, the components in the synchronous lifting system can be transported with the work ship and the work platform separated, and after the work platform is fixed, the components in the synchronous lifting system can be assembled on the work platform.

[0081] In the embodiments provided in the present disclosure, in step S3, the net rack unit is lifted step by step under the control of the synchronous lifting system, so that the net rack unit is separated from the pile foundation structure.

[0082] Before lifting the net rack unit, the method further comprises: performing laser-induced breakdown spectroscopy detection on the damaged components of the net rack unit. By performing laser-induced breakdown spectroscopy detection on the damaged components, the damage degree or damage position of the damaged components can be judged in advance, so as to provide reference for subsequent repair, and data support for subsequent analysis of the damage cause of the damaged components can be provided.

[0083] Specifically, the laser-induced breakdown spectroscopy detection comprises: ablation of the surface of the damaged component using a pulsed laser; analyzing the intensity ratio of Fe (iron) / Cr (chromium) elements in the plasma emission spectrum; and determining the damage degree of the damaged component according to the ratio of each element. Of course, the intensity ratio between other elements in the component and the Fe element can also be used to determine the damage degree of the damaged component, for example, the other element can be Ni (nickel), and the present disclosure does not make specific limitation on the type of other elements. For the net rack unit made of different materials, the determination elements in the damage degree can be adaptively adjusted.

[0084] In some embodiments, when Cr / Fe≤0.18, it can be determined that the damage is serious.

[0085] Before the net rack unit is jacked up, the method further comprises: analyzing and calculating the distribution of the jacking points of the net rack unit to make the stress distribution of the net rack unit uniform. Since the net rack unit is in a marine environment, and the stress distribution of the net rack unit will change after the net rack unit is damaged, in order to improve the reliability of the subsequent operation platform for jacking up the net rack unit, it is necessary to analyze the jacking point distribution of the net rack unit before the net rack unit is jacked up. Specifically, analyzing the distribution of the jacking points of the net rack unit can include: using finite element analysis to analyze the distribution of the jacking points of the net rack unit. The finite element analysis parameters at least include the sea wave load spectrum, the wind speed distribution, and the fatigue curve of the net rack unit. By analyzing the distribution of the jacking points of the net rack unit, the reliability of the subsequent operation platform for jacking up the net rack unit can be improved, and irreversible deformation of the net rack unit during jacking up of the net rack unit can be avoided, so that the net rack unit fails.

[0086] After determining the damage degree of the damaged component and determining the jacking point distribution of the net rack unit, the net rack unit is lifted in stages under the control of the synchronous jacking system, so that the net rack unit is separated from the pile foundation structure, that is, at least the damaged component is separated from the pile foundation structure, and there is a certain gap between the damaged component and the pile foundation structure, so that the net rack unit can be replaced or repaired.

[0087] In some embodiments, since the deformation of the net rack unit in the area where the rod is broken is large, in order to ensure the safety of the net rack unit structure, the synchronous jacking system can be used to restore the deflection of the net rack unit with large vertical deformation. The maximum stress ratio of the net rack unit after deflection restoration is within 1, which can be understood as that the net rack unit has reached the expected deflection requirement.

[0088] In some specific embodiments, after the net rack unit is jacked up to restore the vertical displacement, the maximum stress ratio of the net rack unit is 0.76; the deformed rod in the net rack unit is jacked up to restore the deformation value of the peripheral rod to differ by 1mm-3mm, which is basically consistent with the original structure deformation of the net rack unit. The original structure of the net rack unit refers to the net rack unit without rod breakage or damage.

[0089] In the embodiments provided in the present disclosure, in step S4, the damaged component of the net rack unit is replaced in a critical unloading state.

[0090] In some embodiments, the net rack unit needs to replace the damaged component in a critical unloading state to ensure the reliability of the repair, wherein the critical unloading state includes: the axial force of the target rod decreases to 15%-30% of the initial value; the displacement difference between adjacent bolt balls is ≥1.5mm and ≤3m; the torque attenuation amount of the bolt ball connected to the target rod is ≥40%; wherein the target rod is the damaged component to be replaced.

[0091] The method for replacing damaged components of the space truss unit in the critical unloading state comprises: when the space truss unit is separated from the pile foundation structure to a preset interval, the jacking of the space truss unit is paused; and a pre-tensioned replacement component is installed on the damaged part of the space truss unit. The preset interval can be 0.5 m to 3 m. Under the premise that the preset interval is sufficient to replace the damaged part, the jacking distance of the space truss unit is reduced, and the stress deformation of the space truss unit is reduced. On the other hand, sufficient space is reserved for the subsequent secondary jacking of the space truss unit.

[0092] The method for replacing damaged components of the space truss unit in the critical unloading state comprises: when the space truss unit is separated from the pile foundation structure to a preset interval, the jacking of the space truss unit is paused; and a pre-tensioned replacement component is installed on the damaged part of the space truss unit. The preset interval can be 0.5 m to 3 m. Under the premise that the preset interval is sufficient to replace the damaged part, the jacking distance of the space truss unit is reduced, and the stress deformation of the space truss unit is reduced. On the other hand, sufficient space is reserved for the subsequent secondary jacking of the space truss unit.

[0093] In some embodiments, in order to further improve the reliability and stability of the repair process and facilitate the repair work, the method further comprises: starting the local rigidity compensation device in the critical unloading state to form temporary support for the damaged part of the space truss unit.

[0094] The local rigidity compensation device comprises an inflatable carbon fiber reinforced elastomer pad, and the inside of the pad is injected with a magneto-rheological fluid. By changing the magnetic field strength, the compression modulus of the pad can be adjusted in real time to change the support force of the pad on the damaged part of the space truss unit in real time to meet the temporary support requirement. After the space truss unit is repaired, the local rigidity compensation device can be removed. Of course, in the present disclosure, the local rigidity compensation device can form temporary support for the damaged part of the space truss unit, or the use of the local rigidity compensation device and the support of the local rigidity compensation device can be determined according to the jacking state of the space truss unit by the work platform, for example, when the jacking of the space truss unit by the work platform is not sufficient to form effective support for the local space truss unit, the space truss unit can be jacked by the local rigidity compensation device.

[0095] After replacing the damaged components of the space truss unit in the critical unloading state, the method further comprises: performing dynamic frequency matching debugging. The reliability of the replacement component and the overall matching of the replacement component and the space truss unit are verified, so as to improve the structural strength and service life of the overall space truss unit.

[0096] Wherein, the dynamic frequency matching debugging includes: exciting the repaired grid unit, and collecting vibration signals; extracting the first three order inherent frequencies f1, f2 and f3 of the vibration signals; adjusting the pre-tightening force of the new component until the condition of |(f n f) / f|≤0.5%; wherein, n=1, 2, 3, f n is the inherent frequency of the new component, and f is the inherent frequency of the original component before replacement.

[0097] In the embodiments provided in the present disclosure, in step S5, a pressure-displacement double closed loop control strategy is adopted to stage unload the grid unit, so that the repaired grid unit falls back to the pile foundation structure.

[0098] Wherein, the pressure-displacement double closed loop control strategy adopted to stage unload the grid unit includes: starting the pressure ring to unload the grid unit by the hydraulic jack, and maintaining the oil pressure fluctuation of the hydraulic jack≤±2%; starting the displacement ring to adjust the position of the grid unit by the variable gain PID controller, wherein the gain coefficient of the controller is Wherein, ΔS is the displacement difference of adjacent jacking points, and α=0.8-1.2.

[0099] The pressure-displacement double closed loop control strategy is adopted to stage unload the grid unit, which avoids that the grid unit is deformed by a large stress due to too fast load unloading of the work platform, and improves the repair reliability and stability.

[0100] The repair method provided in the present disclosure is described in detail below with specific embodiments:

[0101] Embodiment one: 400MW photovoltaic array rod replacement.

[0102] Ocean environment parameters: wave height 1.8m, period 6s, salinity 28‰.

[0103] Repair process:

[0104] Step S1, the self-elevating work platform ship drives through the channel in the photovoltaic array to the position below the rod to be repaired;

[0105] Step S2, the pile leg of the work platform is inserted into the seabed, the pile leg is fixed to the seabed, and the pile leg lifts the work platform to separate from the sea level, and the work platform is leveled and fixed by the pile leg leveling system;

[0106] Step S3, the grid unit is lifted in stages under the control of the synchronous jacking system, so that the grid unit is separated from the pile foundation structure, wherein the displacement difference in the synchronous jacking is less than or equal to 0.38mm, and the stress fluctuation is less than 8Mpa.

[0107] Step S4, replacing the damaged components of the truss unit in the critical unloading state; when replacing the damaged components, the local stiffness compensation device can be used to compensate the local stiffness of the truss unit, the magnetic field strength of the local stiffness compensation device is 1.2T, and the node amplitude of the truss unit can be reduced by 73% through the local stiffness compensation; after replacing the damaged components of the truss unit, the pre-tightening force of the new components can be adjusted to satisfy that the absolute value of the change of the frequency is 0.27%, so that the fatigue life of the repaired truss unit is increased to 118%.

[0108] Step S5, using a pressure-displacement double closed loop control strategy to perform staged unloading on the truss unit, so that the repaired truss unit falls back to the pile foundation structure.

[0109] Embodiment two: under the same conditions as in embodiment one, in step S2, the pile leg leveling system comprises a seabed negative pressure adsorption module, and the anti-sea wave performance of the seabed negative pressure adsorption module is shown in Table One:

[0110] Table One

[0111] Sea state Conventional platform displacement amplitude Platform displacement amplitude of the present disclosure 4 35 mm 8 mm 5 Failure 21 mm 6 Failure 50 mm

[0112] As can be seen from Table One, the seabed negative pressure adsorption module provided by the present disclosure can achieve good control effect on the position of the operation platform, and improve the operation stability and operation reliability of the operation platform.

[0113] Through experiments, it is found that, in terms of repair efficiency, under the same marine environment parameter conditions, the replacement time of a single rod provided by the present disclosure is shortened from 4.5 hours to 1.8 hours, the efficiency is improved by 60%, and the repair cost is reduced to 57% of the traditional method; in terms of structural safety of the truss unit, compared with the traditional repair method, the plastic deformation of the node is reduced by at least 23% by the repair method provided by the present disclosure; in terms of the proportion of secondary cracks, the method provided by the present disclosure is reduced by at least 31.2% compared with the traditional method, the repair method provided by the present disclosure can greatly improve the structural strength and structural reliability of the repaired truss unit, and prolong the service life of the truss unit, thereby prolonging the overall service life of the offshore photovoltaic system.

[0114] It should be noted that although the steps of the repair method of the offshore photovoltaic upper support structure in the present disclosure are described in a specific order in the drawings, this does not require or imply that the steps must be performed in this specific order, or that all the steps shown must be performed to achieve the desired results. In addition or alternatively, some steps can be omitted, a plurality of steps can be combined into one step, and / or one step can be divided into a plurality of steps, etc.

[0115] Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the features disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

Claims

1. A method for repairing the superstructure of an offshore photovoltaic system, the superstructure comprising connected grid units and pile foundation structures, the pile foundation structures supporting the grid units, the grid units supporting photovoltaic modules, characterized in that... include: Step S1: Position the self-elevating work platform directly below the space frame unit to be repaired. The self-elevating work platform is equipped with a synchronous jacking system and a pile leg leveling system. Step S2: The legs of the working platform extend into the seabed and are fixed to the seabed. At the same time, the legs lift the working platform off the sea surface and the working platform is leveled by the leg leveling system. Step S3: Under the control of the synchronous jacking system, the space frame unit is lifted in stages to detach the space frame unit from the pile foundation structure; Step S4: Replace the damaged parts of the space frame unit under critical unloading conditions; Step S5: Use a pressure-displacement dual closed-loop control strategy to unload the space frame unit in stages, so that the repaired space frame unit falls back to the pile foundation structure.

2. The repair method for the upper support structure of offshore photovoltaic systems according to claim 1, characterized in that, In step S4, replacing the damaged components of the space frame unit under critical unloading conditions includes: When the space frame unit detaches from the pile foundation structure to a preset distance, the jacking of the space frame unit is suspended; Pre-tensioned replacement parts are installed on the damaged parts of the space frame unit.

3. The repair method for the upper support structure of offshore photovoltaic systems according to claim 2, characterized in that, Install pre-tensioned replacement parts on the damaged parts of the space frame unit, including: Remove the damaged parts at the damaged part of the space frame unit, and use a hoisting rope to lower the damaged parts to the working platform; Install a new component of the same specification. The new component is a pre-tensioned replacement component. One end of the new component is fixed to a bolt ball, and the other end of the new component is suspended by a rope. The space frame unit is then lifted a second time to move it to the installation position. Connect one end of the new component that is suspended to the bolt ball.

4. The repair method for the upper support structure of offshore photovoltaic systems according to claim 2, characterized in that, The critical unloading state includes: The axial force of the target member decreases to 15% to 30% of its initial value; the displacement difference between adjacent bolt balls is ≥1.5mm and ≤3m; the torque attenuation of the bolt balls connected to the target member is ≥40%; wherein, the target member is a pre-replaced damaged component.

5. The repair method for the upper support structure of offshore photovoltaic systems according to claim 1, characterized in that, The method further includes: The local stiffness compensation device is activated under critical unloading conditions to provide temporary support for the damaged parts of the space frame unit. The local stiffness compensation device includes an inflatable carbon fiber reinforced elastomer pad, the inside of which is injected with magnetorheological fluid. The compressive modulus of the pad can be adjusted in real time by changing the magnetic field strength.

6. The repair method for the upper support structure of offshore photovoltaic systems according to claim 1, characterized in that, In step S5, a pressure-displacement dual closed-loop control strategy is used to perform graded unloading of the space frame unit, including: The pressure ring is activated by a hydraulic jack to unload the pressure of the grid unit, and the oil pressure fluctuation of the hydraulic jack is maintained at ≤±2%. The position of the space frame unit is adjusted by starting a displacement loop using a variable gain PID controller, wherein the gain coefficient of the controller is... Where ΔS is the displacement difference between adjacent jacking points, and α = 0.8 - 1.

2.

7. The repair method for the upper support structure of offshore photovoltaic systems according to claim 6, characterized in that, The synchronous lifting system includes: A lifting support, the height of which is adjustable from 10m to 25m; A hydraulic jack, wherein the stroke of the hydraulic jack is ≥500mm; Lifting linkage rod with universal joint structure; distributed hydraulic pump station; PLC control console with variable gain PID controller; The PLC control console is used to adjust the hydraulic pressure provided by the distributed hydraulic pump station in real time according to the lifting status of the grid unit, so as to control the distance and lifting force of the hydraulic lifting jacks in lifting the grid unit.

8. The repair method for the upper support structure of offshore photovoltaic systems according to claim 1, characterized in that, Before lifting the space frame unit, the following steps are also included: Performing laser-induced breakdown spectroscopy detection on the damaged component includes: The surface of the damaged component was ablated using a pulsed laser. Analyze the Fe / Cr elemental intensity ratio in the plasma emission spectrum; The degree of damage to the damaged component is determined based on the proportion of each element, wherein when Cr / Fe ≤ 0.18, it is considered severely damaged.

9. The repair method for the upper support structure of a marine photovoltaic system according to claim 1, characterized in that, After replacing the damaged components of the space frame unit under critical unloading conditions, the process also includes: performing dynamic frequency matching debugging; Perform dynamic frequency matching debugging, including: The repaired space frame unit is excited, and vibration signals are collected; Extract the first three natural frequencies f1, f2, and f3 of the vibration signal; Adjust the preload of the new component until it meets |(f) n -f) / f∣≤0.5%; where n=1,2,3, fn is the natural frequency of the new component, and f is the natural frequency of the original component before replacement.

10. The repair method for the upper support structure of a marine photovoltaic system according to claim 1, characterized in that, Before step S3, the following is also included: The layout of the lifting points distributed in the space frame unit is analyzed and calculated to make the stress distribution of the space frame unit more uniform.

11. The repair method for the upper support structure of a marine photovoltaic system according to claim 10, characterized in that, The layout of the lifting points distributed in the space frame units is analyzed and calculated, including: The jacking point layout of the space frame unit is analyzed using finite element analysis; wherein the finite element analysis parameters include at least the wave load spectrum, wind speed distribution, and fatigue curve of the space frame unit.

12. The repair method for the upper support structure of a marine photovoltaic system according to claim 1, characterized in that, The pile leg leveling system includes a seabed negative pressure adsorption module, which is installed at the bottom of each pile leg; wherein the adsorption force of the seabed negative pressure adsorption module is ≥200kN / m. 2 .

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