Photovoltaic array mooring device considering floating box offset

Abstract

The invention belongs to the technical field of mooring, and discloses a photovoltaic array mooring device considering buoyancy tank offset, which comprises a fixed pile, a support rod, an anchor chain, a buoyancy tank, a hook and a weight, the fixing piles are connected with struts through anchor chains; supporting rods are fixed in the centers of the top surfaces of the buoyancy tanks through screws; four corners of the buoyancy tank are connected with fixing piles through anchor chains. According to the photovoltaic array mooring device considering the floating box deviation, the situation that due to the influence of water flow and wind speed, the whole floating type square matrix rotates and rotates, anchor chains of the floating type square matrix are twisted, and consequently the tension of individual anchor chains is too large, and even the anchor chains are wound is avoided. The system pays attention to the anchor chain connecting position of the whole floating type square matrix. Balancing weights are applied to the anchor chain, and the number and the placement distance of the balancing weights are mainly arranged according to the weakest anchor chain position obtained through joint solution.

Description

Technical Field

[0001] This invention belongs to the field of mooring technology, and particularly relates to a photovoltaic array mooring device that takes into account the offset of the buoy. Background Technology

[0002] Floating photovoltaic (PV) power plants in China are still in their infancy and are in the exploratory stage. Since 2015, some domestic companies have been experimenting with using floating structures to lift the metal supports of PV power plants from the water surface, solving the problem of using pile foundations in deep water. In July 2015, an 8MWp floating PV power plant was connected to the grid in Linxi County, Hebei Province. This power plant used PVC pipes to make rafts to directly support the PV modules and connecting supports. In December 2015, an 8.5MWp floating PV power plant was connected to the grid in Sanshan, Wuhu; in March 2016, a 15MWp floating PV power plant was connected to the grid in the Huainan coal subsidence area. The latter two types of power plants followed the construction model of terrestrial PV power plants, using metal supports to place the PV modules at the optimal tilt angle, and using engineering plastic rectangular floating boxes at the bottom to support the PV modules. Because the metal supports are heavy, a large number of floating bodies are required, resulting in high costs. On the other hand, PV power plants are difficult to balance in water, and are prone to capsizing under wind pressure. In 2016, my country's National Energy Administration designated the coal mine subsidence areas in the Huaihe River Basin as photovoltaic (PV) leader bases, encouraging companies to build PV power plants in the waters of these areas. The water depth in coal mine subsidence areas typically ranges from 10 to 30 meters. To construct reliable and stable PV power plants, domestic companies have been emulating international best practices in building PV power plants in deep water, making floating PV power plants a popular research topic as a new construction model. However, existing technologies suffer from rotational issues due to water flow and wind speed, causing the anchor chains of floating arrays to twist, resulting in excessive tension on some anchor chains and even entanglement.

[0003] Based on the above analysis, the problems and shortcomings of the existing technology are as follows:

[0004] (1) Existing technology causes the anchor chains of the floating array to twist due to the influence of water flow and wind speed, resulting in excessive tension on individual anchor chains or even entanglement.

[0005] (2) Existing technology causes the anchor chains of the floating array to twist due to the influence of water flow and wind speed, resulting in excessive tension on individual anchor chains or even entanglement.

[0006] (3) The water level in the coal mine subsidence area is different. Since the anchor chain length of the anchor point is designed according to the highest water level and the length is different, when the water area where the photovoltaic is located is in the dry season, when the water level drops, the horizontal direction will be displaced due to wind and waves and other loads. Due to the different anchor chain lengths, the offset is different, resulting in a relatively short design anchor chain tension concentration. Summary of the Invention

[0007] To address the problems existing in the prior art, the present invention provides a photovoltaic array mooring device that takes into account the offset of the pontoon.

[0008] The present invention is implemented as follows: a photovoltaic array mooring device that takes into account buoy offset includes:

[0009] Fixed piles, supports, anchor chains, pontoons, hooks, and weights;

[0010] The fixed piles are connected to the support rods via anchor chains; the support rods are fixed to the center of the top surface of the pontoon with screws; the four corners of the pontoon are connected to the fixed piles via anchor chains.

[0011] The anchor chain is made of nickel-titanium alloy memory cable (phase change temperature 25℃), maintaining high stiffness at room temperature (EA=8×10). 4 When the pontoon offset exceeds the threshold (1.2m), an austenitic phase transformation is triggered by an embedded heating wire, causing the cable to instantly elongate by 35% and absorb the impact energy. The auxiliary anchor chain is equipped with a magnetorheological elastomer (MRE) damper, which adjusts the shear modulus (0.1-5MPa adjustable) in real time through an external magnetic field to suppress high-frequency vibration (attenuation rate >70% in the 5-20Hz frequency band).

[0012] The interior of the weight is filled with a mixture of ferromagnetic particles and silicone oil; the particle distribution is adjusted by an electromagnetic coil to achieve dynamic shift of the center of mass within a range of 0.3m, balancing the asymmetrical load of the tidal current; an integrated piezoelectric power generation unit is used to generate electricity by the vibration of the weight (output power up to 15W) to power the sensor system.

[0013] The corner connection of the float box adopts a universal hinge-hydraulic buffer composite joint, including:

[0014] Ball joint structure: allows for ±15° free swing, avoiding excessive bending of the anchor chain (minimum bending radius reduced from 0.5m to 0.2m);

[0015] Hydraulic damping chamber: Built-in silicone oil + spring combination to provide axial buffer (damping coefficient adjustable from 2-10kN·s / m);

[0016] Tension equalizers are added to the ends of the anchor chains to automatically distribute the force on the four corner anchor chains through a differential gear mechanism (unbalance <5%).

[0017] Furthermore, a hook is welded to the bottom of the anchor chain.

[0018] Furthermore, a weight is attached to the bottom of the hook.

[0019] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0020] This invention considers a photovoltaic array mooring device with offset pontoons, ensuring the entire floating array avoids rotation caused by water flow and wind speed, which could lead to torsion of the anchor chains, excessive tension in individual anchor chains, or even entanglement. The system focuses on the anchor chain connections throughout the floating array. Counterweights are applied to the anchor chains, with the number and spacing determined primarily by the weakest anchor chain location determined through a joint analysis. Attached Figure Description

[0021] Figure 1 This is a structural diagram of a photovoltaic array mooring device considering buoy offset provided in an embodiment of the present invention.

[0022] Figure 2 This is a structural diagram of the anchor chain provided in an embodiment of the present invention.

[0023] Figure 3 This is an overall layout diagram of the suction anchor, mooring line, and float provided in an embodiment of the present invention.

[0024] Figure 4 This is a force analysis and geometric relationship diagram of an underwater anchor chain provided in an embodiment of the present invention.

[0025] In the diagram: 1. Fixed pile; 2. Support rod; 3. Anchor chain; 4. Floating box; 5. Hook; 6. Weight. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] Example 1: Photovoltaic Array Mooring System Applicable to Inland Reservoirs

[0028] When deploying a photovoltaic power generation array in a mountainous reservoir, the mooring device described in this invention is used for fixation. The system has an anchor chain installed at each of the four corners of each pontoon, connected to four fixed piles at the bottom of the reservoir, achieving multi-point flexible positioning. A vertical support rod is installed at the top of the pontoon, and the bottom of the support rod is connected to the central fixed pile at the bottom of the reservoir via a central anchor chain, providing a return force in case of pontoon displacement. All anchor chains have hook structures welded to their bottom ends for quick changes in anchoring methods. This configuration effectively resists pontoon displacement caused by sudden winds and waves in mountainous areas, ensuring the stable operation of the power generation array.

[0029] Example 2: Floating photovoltaic array mooring system suitable for intertidal waters

[0030] When deploying floating photovoltaic systems in the intertidal zone along the coast, a mooring method incorporating a weighted hook structure is employed. Anchor chains are installed at the four corners of the pontoon, with a hook structure welded to the bottom of each chain. The lower part of the hook is detachably connected to a weight (each weighing approximately 500 kg) via a pin. Since it is difficult to install anchor piles on the seabed, the weights replace traditional anchoring points, providing downward pull through their own weight to prevent the pontoon from drifting with the tides. Simultaneously, a support rod is installed at the center of the pontoon, connected to a shallowly buried anchor pile near the shore via an anchor chain, achieving overall restraint. This device exhibits excellent adaptability and structural stability in areas with large tidal ranges.

[0031] During the long-term operation of floating photovoltaic systems, the pontoons are easily affected by disturbances such as wind, water flow, and waves on the water surface, leading to drift and attitude deviation, which in turn can cause structural safety hazards such as array misalignment, uneven tension, and loosening of anchors. Existing floating photovoltaic mooring structures generally suffer from excessive rigidity, insufficient buffering performance, and poor resistance to attitude disturbances, making it difficult to effectively balance fixation strength and flexible adaptability, thus limiting the stable operation and expanded application of photovoltaic platforms in complex hydrological environments.

[0032] This invention proposes a photovoltaic array mooring device that considers pontoon offset. Through an innovative floating anchor chain structure and a multi-point flexible connection mechanism, it solves the problems of excessive rigidity, limited buffer space, and sluggish structural response in traditional fixed mooring methods. The device utilizes a multi-point anchor chain connection structure at the four corners of the pontoon, employing flexible anchor chains to achieve self-adjustment of tension during pontoon offset, and introduces a weight-sag mechanism, significantly enhancing the system's vertical stability and attitude recovery capability, and improving its dynamic response performance to flow disturbances.

[0033] The support rod, as the core load-bearing element, is located at the center of the top surface of the pontoon. Through a mechanical connection, it forms a rigid force transmission channel with the pontoon, ensuring the structural stability and reliable load transfer of the entire system. Simultaneously, one end of the support rod is connected to the shore foundation or underwater fixed pile via an anchor chain. During system disturbances, the flexible tension of the anchor chain absorbs external impacts, achieving mechanical hysteresis buffering and displacement balance, thereby effectively reducing the risk of localized stress concentration and fatigue crack formation.

[0034] To further enhance the vertical anti-buoyancy capability of the anchoring system, this invention adds a welded hook to the bottom of the anchor chain and mounts a high-density weight structure at its lower end. This weight serves two purposes: firstly, it allows for the continuous release of the buoy's vertical restoring force through gravity; secondly, it generates sinking inertia during wave disturbances, acting as a stabilizer for the buoy's attitude. Compared to traditional anchor chains without counterweights, this structure significantly reduces the amplitude of the photovoltaic array's pitch angle change under wind and wave coupling, ensuring stable output from the photovoltaic panels.

[0035] Furthermore, the hook structure of this mooring device is made of high-strength, corrosion-resistant alloy, exhibiting excellent fatigue resistance and durability. Its connection to the anchor chain and weights is detachable, facilitating future maintenance and adjustments, thus enhancing the system's maintainability and modular expansion capabilities. The tension between the buoy and the anchor chain is transmitted through this hook, achieving non-linear, gradual release. This allows for adaptive and dynamic adjustment of the anchoring force field during water level changes, enhancing the floating safety margin of the surface photovoltaic array.

[0036] The photovoltaic array mooring device considering buoy offset proposed in this invention not only has both rigid support and flexible buffer properties in structure, but also effectively overcomes the instability problem of floating photovoltaic structures caused by environmental disturbances through mechanical self-adjustment mechanism, providing a key supporting technical foundation for the highly reliable deployment of floating photovoltaic systems in complex waters such as lakes, reservoirs, and nearshore areas.

[0037] like Figure 1 As shown, an embodiment of the present invention provides a photovoltaic array mooring device that takes into account buoy offset, comprising:

[0038] 1. Fixed pile; 2. Support rod; 3. Anchor chain; 4. Floating box; 5. Hook; 6. Weight.

[0039] The fixed pile 1 is connected to the support rod 2 by the anchor chain 3; the support rod 2 is fixed to the center of the top surface of the pontoon 4 by screws; the four corners of the pontoon 4 are connected to the fixed pile 1 by the anchor chain 3.

[0040] The anchor chain 3 is made of nickel-titanium alloy memory cable (phase change temperature 25℃), which maintains high rigidity at room temperature (EA=8×10). 4 When the pontoon offset exceeds the threshold (1.2m), an austenitic phase transformation is triggered by an embedded heating wire, causing the cable to instantly elongate by 35% and absorb the impact energy. The auxiliary anchor chain is equipped with a magnetorheological elastomer (MRE) damper, which adjusts the shear modulus (0.1-5MPa adjustable) in real time through an external magnetic field to suppress high-frequency vibration (attenuation rate >70% in the 5-20Hz frequency band).

[0041] The interior of the weight 6 is filled with a mixture of ferromagnetic particles and silicone oil; the particle distribution is adjusted by an electromagnetic coil to achieve dynamic shift of the center of mass within a range of 0.3m, balancing the asymmetrical load of the tidal current; an integrated piezoelectric power generation unit is used to generate electricity by the vibration of the weight (output power up to 15W) to power the sensor system.

[0042] The four corners of the pontoon are connected using a universal hinge-hydraulic buffer composite joint, including:

[0043] Ball joint structure: allows for ±15° free swing, avoiding excessive bending of the anchor chain (minimum bending radius reduced from 0.5m to 0.2m);

[0044] Hydraulic damping chamber: Built-in silicone oil + spring combination to provide axial buffer (damping coefficient adjustable from 2-10kN·s / m);

[0045] A tension equalizer is added to the end of anchor chain 3, which automatically distributes the force on the four corner anchor chains through a differential gear mechanism (unbalance <5%).

[0046] Combination Figure 2 and Figure 3 The anchoring structure design provided in this embodiment of the invention fully considers the mechanical response and structural stability caused by buoy displacement. Figure 2 In the structure shown, the bottom of the anchor chain 3 is connected to the hook 5 by welding, and the bottom of the hook 5 is further attached to a weight 6. This design enables the anchor chain to not only have flexible connection and tension self-adjustment functions, but also to provide additional downward pulling force through the gravity of the weight, effectively improving the attitude recovery capability and system stability of the pontoon under vertical disturbances.

[0047] Existing floating photovoltaic (PV) systems often face problems such as float array misalignment, rotational instability, and structural stress concentration caused by uneven anchoring when operating in complex aquatic environments, especially during sudden storms or drastic changes in water flow. Traditional single-point or rigid mooring structures lack sufficient flexible buffering and multi-directional restraint capabilities, making it difficult to adapt to dynamic environmental changes. This can lead to PV module misalignment, damaged component connections, reduced power generation efficiency, and even potential safety accidents. Therefore, there is an urgent need for a float mooring device with multi-point flexible support capabilities and the ability to adaptively absorb drift stress to enhance overall operational stability.

[0048] The photovoltaic array mooring device proposed in this invention provides a central pulling torque when the pontoon shifts as a whole by setting a support rod 2 at the top center of the pontoon 4 and connecting it to a central fixed pile 1 with an anchor chain 3, thus limiting its translational tendency. At the same time, anchor chains 3 are set at the four corners of the pontoon 4 and anchored to fixed piles 1 laid on the surrounding seabed. This "center-corner point" joint mooring method constructs a flexible constraint system with multi-directional tension distribution, effectively enhancing the attitude stability of the floating structure and its self-recovery capability under wave disturbance.

[0049] The anchor chain 3 in the device is made of high-strength alloy steel, which has good corrosion resistance and tensile strength. The bottom end is welded with a hook 5 to simplify reconstruction and maintenance. The support rod 2 is connected to the top of the pontoon via a flange. The support rod structure is a hollow embedded design, which reduces weight and improves stability. The hook 5 can be fitted with a weight 6, which is suitable for water environments with muddy or sandy bottoms or where it is difficult to lay fixed piles. In this way, gravity anchoring can replace the traditional ground pile structure, which greatly improves the system's adaptability.

[0050] During operation, the pontoon 4 experiences slight displacement under wind loads or water flow impacts. The anchor chain 3 connected to the central support 2 initially senses tension, generating a primary traction reaction force. As the displacement continues to expand into the corner area, the four corner anchor chains 3 are sequentially tightened, forming a multi-point tension coordinated response. Ultimately, the pontoon's position is dynamically stabilized under a balanced tension distribution. This distributed flexible mooring strategy avoids localized structural fatigue caused by concentrated forces, ensuring the operational reliability of the photovoltaic modules.

[0051] Furthermore, this device features a highly modular structure, facilitating installation and maintenance. The anchor chain length, anchor point location, and weight mass can be flexibly configured according to the specific wave parameters and pontoon arrangement of the waterway, adapting to the needs of various scales and forms of floating photovoltaic scenarios. The system possesses excellent engineering adaptability and scalability, making it suitable for widespread application in various complex water areas such as lakes, reservoirs, and coastal mudflats.

[0052] This invention constructs a multi-point flexible mooring system that considers the offset response characteristics of the pontoon by setting a main anchorage in the center of the pontoon, arranging auxiliary anchor chains at the four corners, and supplementing it with a hook weight structure. This not only significantly improves the anti-interference capability and return performance of the floating array in complex environments, but also provides a structural support foundation for the efficient and stable operation of the surface photovoltaic system.

[0053] Figure 3 This demonstrates the catenary arrangement of the anchor chain in water. One end of the anchor chain is fixed to an underwater anchor pile, and the other end is connected to a buoy via a support rod. The anchor chain, under the combined action of its own weight and the tension caused by the buoy's displacement, forms a natural drooping curve. Under the influence of a current velocity U, the buoy shifts laterally, causing a change in the anchor chain's shape. The tension on the anchor chain gradually increases from $T_p$ at the bottom to $T_s$ at the top. The shape of the curve is influenced by buoyancy, tension, and the angle of entry into the water ($\theta_p,\theta_s$).

[0054] To quantify the stress state and deformation process of the anchor chain, this invention introduces the mechanical governing equations for the underwater suspension chain segment, which are expressed as follows:

[0055]

[0056] Where T is the anchor chain tension, w is the buoyancy density per unit length in water, A is the cross-sectional area of ​​the anchor chain, E is the elastic modulus, θ is the angle between the tension direction and the horizontal plane, and Ft and Fn represent the tangential and normal hydrodynamic forces, respectively.

[0057] Based on the selection of the above model parameters and the geometric arrangement of the anchor chain, this invention can achieve dynamic feedback control of anchor chain tension and attitude angle. During array operation, the horizontal displacement or vertical fluctuation of the pontoon can be automatically adjusted to maintain its equilibrium position through the flexible structure of the anchor chain. Combined with the additional inertial stabilizing effect of the weight, this effectively mitigates the dynamic response of the system structure in wind and wave environments, extends the service life of the mooring system, and improves the operational safety of the power generation unit. Figure 4 In the middle, the force governing equation for the anchor chain is:

[0058]

[0059] Where T is the anchor chain tension, w is the buoyancy density of the anchor line per unit length in the water, and A is the cross-sectional area of ​​the anchor line, E.

[0060] When the water level is not at its highest, counterweights should be placed on longer anchor chains, but the mass of these counterweights should not be too large. This is because if the counterweight is too large, it will sink to the bottom, and if its weight is much greater than the breaking load of the anchor chain, it will essentially break the anchor chain and fix it to the bottom. The most suitable counterweight scheme is one with moderate weight, preventing the anchor chain from sinking to the bottom while reducing sensitivity to anchor chain movement.

[0061] When the anchor chain is designed to be at its highest water level, a drop in water level can cause tension concentration in the shorter anchor chain, potentially breaking the floating photovoltaic array. The purpose of adding a counterweight in this situation is to increase the buoyancy of the longer anchor chain, allowing it to withstand the tension during a drop in water level. This reduces the excessive tension on the shorter anchor chain and also helps to keep one side of the floating photovoltaic array as straight as possible, preventing deformation and damage to the array.

[0062] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A floating photovoltaic array mooring system, comprising a buoy, support rods, anchor chains, anchor piles, hooks, and weights, characterized in that: The top of the pontoon is fixed with a support rod, and the bottom end of the support rod is connected to a fixed pile via an anchor chain. Each corner of the pontoon is equipped with an anchor chain that is connected to a fixed pile to achieve multi-point flexible positioning; The anchor chain is a nickel-titanium alloy memory cable with an axial stiffness modulus of 8 x 10^4 kN / m at room temperature. When the buoy deflection exceeds 1.2 meters, a phase change is triggered by heating the cable core wire, so that the instantaneous elongation of the cable reaches 35%. A magnetorheological elastomer damper is connected in series on the outside of the anchor chain. Its shear modulus can be adjusted in the range of 0.1 to 5 MPa to attenuate vibrations of 5 to 20 Hz. The heavy block is filled with a mixture of ferromagnetic particles and silicone oil, and the particle distribution is changed by an electromagnetic coil to enable the center of mass to move within a range of 0.3 meters. At the same time, a piezoelectric power generation unit is integrated to power the sensor system.

2. The mooring system as claimed in claim 1, characterized in that, The magnetorheological elastomer damper adjusts its shear modulus by controlling the current in the electromagnetic coil in real time.

3. The mooring system as claimed in claim 1, characterized in that, The support rod and the pontoon are fastened with bolts and anti-loosening locking plates are installed on the contact surface to form a rigid force transmission unit.

4. The mooring system as claimed in claim 1, characterized in that, The anchor chain forms a catenary structure underwater and satisfies the mechanical control condition that the product of the square of the anchor chain tension minus twice the buoyant weight per unit length, the elastic modulus, and the cross-sectional area equals zero.

5. The mooring system as claimed in claim 1, characterized in that, The pontoons, struts, anchor chains, hooks, and weights are modularly connected for easy disassembly and maintenance and are suitable for lakes, reservoirs, and nearshore waters.

6. A shape memory alloy anchor chain assembly, comprising a nickel-titanium alloy cable core, a heating wire, and an outer wear-resistant sheath, characterized in that: The cable core retains its martensitic phase below 25 degrees Celsius; When the temperature control module drives the heating wire to raise the temperature of the cable core to above 35 degrees Celsius, the cable core transforms into the austenitic phase and produces an axial elongation of not less than 35 percent. The outer sheath is made of wear-resistant composite material and has seawater corrosion resistance.

7. The anchor chain assembly as claimed in claim 6, characterized in that, The outer layer of the cable core is covered with an integrated magnetorheological elastomer layer to provide variable shear damping.

8. A universal joint hydraulic buffer composite joint, comprising a ball joint, a hydraulic damping cavity, and a positioning locking pin, characterized in that: The ball joint allows the pontoon and anchor chain to swing freely within a 15-degree spatial angle range; The hydraulic damping chamber is filled with silicone oil and works with springs to generate axial damping of two to ten kilonewtons per meter. The positioning locking pin automatically locks in static conditions to eliminate free swing.

9. The composite joint as described in claim 8, characterized in that, The ball joint housing is made of seawater-resistant stainless steel and is integrally formed with the anchor chain end ring by friction welding to reduce the minimum bending radius to 0.2 meters.

10. An anchor chain tension equalizer, comprising a differential gear mechanism, a drive synchronizing wheel, and four sets of output ends, characterized in that: The input end of the differential gear mechanism is fixed to the main body of the pontoon, and the four output ends are connected to the four corner anchor chains respectively. The gear transmission ratio is automatically adjusted according to the force on each anchor chain, so that the tension difference of the anchor chain is kept less than five percent.

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