Offshore buoyancy and gravity composite energy storage method and device

Abstract

The invention discloses an offshore buoyancy and gravity composite energy storage method and device, and the method comprises the steps: building an ocean platform on the sea, installing a pulley block and a motor unit on the ocean platform, arranging a transmission cable in linkage with the motor unit in a penetrating manner on the pulley block, and fixing a first weight and a floating body at the two ends of the transmission cable respectively, a second weight with the same weight as the first weight is installed at the bottom of the floating body, the buoyancy of the floating body is slightly smaller than the gravity of the second weight, during energy storage, the electric drive motor unit lifts the first weight to the high position and fixes the first weight, the second weight drags the floating body to sink, energy is stored, and during energy release, the first weight is released, and the floating body sinks. The transmission cable is tensioned by the first weight and the second weight, the floating body ascends to return to the sea surface, the first weight sinks to return to the low position, in the ascending process of the floating body, the transmission cable drives the motor unit to generate electricity, and electric energy storage, pulleys, electrical equipment and the like which are combined through buoyancy and gravity are all built on the offshore platform through energy storage and energy release circulation, so that installation and maintenance are convenient.

Description

Technical Field

[0001] The invention relates to the technical field of energy storage, in particular to a method and a device for buoyancy-gravity composite energy storage for offshore use. Background Art

[0002] Mechanical energy storage (including solid gravity potential energy storage and pumped storage) technology is to transport solid heavy objects or water to high places to store potential energy, release the heavy objects or water when power generation is needed, convert them into mechanical energy through corresponding transmission devices, and finally convert them into electrical energy through generators.

[0003] Traditional mechanical energy storage projects rely on large height differences, and the best project location is to build the project according to the existing terrain environment (such as solid gravity potential energy storage projects are built in cliffs, deep pits, etc., and pumped storage uses high-altitude reservoirs to store and release water). However, these conditions are relatively special and cannot be used as a universal solution for large-scale energy storage. Therefore, the existing conventional method is to artificially build high platforms or dig deep wells, but no matter which method is used, it has a large amount of engineering. In addition, the use of solid heavy objects for energy storage may occupy valuable land resources or interfere with surrounding production and life.

[0004] Technically, during the discharge process of pumped storage projects, regulating valves, speed regulators, etc. can be used to accurately control the flow of water, thereby controlling the stability of power generation. However, for solid gravitational potential energy storage projects, solid heavy objects follow the law of free fall when falling and are in accelerated motion, while power generation requires uniform motion. Therefore, during the power generation process, a reverse force needs to be applied to slow down the acceleration and make it uniform to maintain the stability of power generation. Although the speed can be controlled by methods similar to the balancing iron block in the elevator shaft, this will also consume some electrical energy and increase the complexity of the control project and equipment. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a method and device for buoyancy-gravity composite energy storage for offshore use.

[0006] The technical solution adopted by the present invention to solve its technical problem is: A method of buoyancy-gravity composite energy storage for use at sea, the method comprising: establishing a mobile or fixed marine platform at sea, installing a pulley block and a motor unit on the marine platform, passing a transmission cable linked to the motor unit through the pulley block, fixing a first weight at one end of the transmission cable, fixing a floating body at the other end, and installing a second weight having the same weight as the first weight at the bottom of the floating body, when the floating body and the second weight are completely immersed in seawater, the buoyancy of the floating body is slightly less than the weight of the second weight, and the initial state is that the first weight sinks on the seabed or hangs in the seawater, and is located At the low point, the floating body floats on the sea surface. When storing energy, the electric power drives the motor unit to lift the first weight to the high point and fix it. The second weight drags the floating body to sink to store energy. When releasing energy, the first weight is released, and the transmission cable is tightened by the first weight and the second weight of equal weight, and the pulling forces on the transmission cable offset each other. The floating body rises back to the sea surface, and the first weight sinks back to the low point. During the rising process of the floating body, the transmission cable drives the motor unit to generate electricity, and the buoyancy-gravity composite power energy storage is achieved through the energy storage and release cycle.

[0007] A buoyancy-gravity composite energy storage device for use at sea, comprising a mobile or fixed marine platform established at sea, a pulley block and a motor unit installed on the marine platform, a transmission cable linked to the motor unit passing through the pulley block, a first weight fixed to one end of the transmission cable, a floating body fixed to the other end, and a second weight with the same weight as the first weight installed at the bottom of the floating body, when the floating body and the second weight are completely immersed in seawater, the buoyancy of the floating body is slightly less than the weight of the second weight.

[0008] The pulley group includes a first pulley, a second pulley, a third pulley, and a fourth pulley. The third pulley and the fourth pulley have the same installation height, and the second pulley has the lowest installation height. The transmission cable passes through the first pulley, the second pulley, the third pulley, and the fourth pulley in sequence, and the second pulley is connected to the motor unit in terms of transmission.

[0009] The motor unit comprises a generator motor unit and a drive motor unit, wherein the generator motor unit and the drive motor unit are connected to a first gear through a clutch transmission gear box, and the first gear rotates synchronously with the second pulley.

[0010] The marine platform is provided with a weight launching area and a floating body launching area corresponding to the first weight and the floating body, a movable load-bearing plate for placing the first weight is installed on the weight launching area, and an elastic edging is installed on the edge of the floating body launching area.

[0011] A groove similar to the lower end of the first weight is arranged in the middle of the load-bearing plate, the lower end of the first weight is placed on the groove, and an elastic buffer pad is placed between the first weight and the groove.

[0012] The upper and lower ends of the first weight and the upper end of the floating body are all streamlined structures.

[0013] The second weight is composed of a plurality of weight components, and the weight components are evenly distributed on the outer side of the lower end of the floating body.

[0014] The weight assembly comprises a support plate fixed on the bottom of the floating body, a mounting frame with an opening at the lower end is mounted on the lower end of the support plate, and a support leg reset by a spring is mounted on the mounting frame.

[0015] The beneficial effects of the present invention are: Pulleys, electrical equipment, etc. are all built on offshore platforms for easy installation and maintenance. They have little impact on the inland environment, will not occupy farmland or land, and will not affect the surrounding transportation and production and living environment. The vast sea area provides ample space and there is no need to worry about occupancy issues.

[0016] There is no need to build high towers or dig deep wells. The characteristics of the ocean's depth can easily solve the space problem of rising and lowering heavy objects, making it suitable for large-scale engineering construction.

[0017] Compared with the free fall of heavy objects, the speed of the rising motion of a floating body can be better controlled to achieve uniform motion, which is more suitable for power generation and can also more effectively utilize buoyancy potential energy for energy conversion. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0019] Figure 1 is a schematic diagram of the present invention in an energy storage state; Figure 2 is a schematic diagram of the present invention in a daily state (non-energy storage state); Figure 3 It is a schematic diagram of the transmission relationship between the motor unit, the clutch speed change gear box and the pulley block; Figure 4 This is a schematic diagram of the state when the second weight does not touch the seabed; Figure 5 This is a schematic diagram of the state when the second weight touches the seabed; Figure 6 It is a bottom view of the floating body; Figure 7 This is a schematic diagram of the load-bearing plate. DETAILED DESCRIPTION

[0020] To make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in combination with specific implementations and with reference to the accompanying drawings. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0021] It is to be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention.

[0022] Some embodiments of the present invention are described below in conjunction with the accompanying drawings.

[0023] Reference Figure 1-7 A method of buoyancy-gravity composite energy storage for use at sea, the method comprising: establishing a mobile or fixed marine platform at sea, installing a pulley block and a motor unit on the marine platform, passing a transmission cable linked to the motor unit through the pulley block, fixing a first weight at one end of the transmission cable, fixing a floating body at the other end, and fixing a second weight having the same weight as the first weight at the bottom of the floating body, when the floating body and the second weight are completely immersed in seawater, the buoyancy of the floating body is slightly less than the weight of the second weight, and the initial state is that the first weight sinks to the seabed or hangs in the seawater, and the first weight is located at a position lower than the first weight. At the low point, the floating body floats on the sea surface. When storing energy, the electric power drives the motor unit to lift the first weight to the high point and fix it. The second weight drags the floating body to sink and stores the energy. When releasing energy, the first weight is released, and the transmission cable is tightened by the first weight and the second weight of the same weight, and the pulling forces on the transmission cable offset each other. The floating body rises back to the sea surface, and the first weight sinks back to the low point. During the rising process of the floating body, the transmission cable drives the motor unit to generate electricity, and the buoyancy-gravity composite power energy storage is achieved through the energy storage and release cycle.

[0024] A buoyancy-gravity composite energy storage device for use at sea, comprising a mobile or fixed marine platform 1 ( Figure 1 , 2 A is a schematic diagram of the sea level), a pulley block and a motor unit are installed on the marine platform 1, a transmission cable 2 linked to the motor unit is passed through the pulley block, a first weight 3 is fixed to one end of the transmission cable 2, a floating body 4 is fixed to the other end, and a second weight 5 with the same weight as the first weight is installed at the bottom of the floating body 4. When the floating body 4 and the second weight 5 are completely immersed in seawater, the buoyancy of the floating body 4 is slightly smaller than the gravity of the second weight 5. When the floating body 4 and the second weight 5 are placed in the sea separately, the second weight 5 will drag the floating body 4 to sink.

[0025] The offshore platform 1 can be a fixed offshore platform, such as a booster cabin for offshore wind power, an oil drilling platform, etc., or a floating offshore body such as a large ship. Pulleys, electrical equipment (including motors, controllers, etc.), etc. are all built on the offshore platform for easy installation and maintenance; the impact on the inland environment is small, and it will not occupy farmland or land, nor will it affect the surrounding transportation and production and living environment. The vast sea area provides sufficient space and there is no need to worry about occupation issues; there is no need to build high towers or dig deep wells like energy storage projects such as solid gravity potential energy storage. The space problem of the rise and fall of heavy objects can be easily solved by utilizing the characteristics of the ocean depth, which is more suitable for large-scale engineering construction.

[0026] The pulley group includes a first pulley 6, a second pulley 7, a third pulley 8, and a fourth pulley 9. The third pulley 8 and the fourth pulley 9 have the same installation height, and the second pulley 7 has the lowest installation height. The transmission cable 2 passes through the first pulley 6, the second pulley 7, the third pulley 8, and the fourth pulley 9 in sequence, and the second pulley 7 is connected to the motor unit in terms of transmission.

[0027] refer to Figure 1 , 2 In this embodiment, the installation heights of the first pulley 6, the third pulley 8 and the fourth pulley 9 are consistent, the installation height of the second pulley 7 is lower than these three pulleys, and the two sides of the second pulley 7 are parallel to the tangent lines of the first pulley 6 and the third pulley 8. When the transmission cable 2 passes through each pulley, the central angle of the second pulley 7 covered by the transmission cable 2 reaches 180°, and the torque transmission to the shaft is more balanced. The arrangement here can improve the stability and safety of the system operation.

[0028] In addition, the present invention may also adopt different pulley block designs, as long as the same effect can be achieved.

[0029] The motor unit comprises a generator motor unit 10 and a drive motor unit 11 , wherein the generator motor unit 10 and the drive motor unit 11 are connected to a first gear 12 via a clutch transmission gearbox, and the first gear 12 rotates synchronously with the second pulley 7 .

[0030] refer to Figure 3The clutch speed change gearbox includes a clutch gear 22, a speed increasing gear set 23, and a speed reducing gear set 24. The clutch gear 22 is always meshed with the first gear 12. The output shaft of the generator motor unit 10 is connected to a second gear 26 through a coupling 25. The second gear 26 is meshed with the speed increasing gear set 23. The output shaft of the drive motor unit 11 is fixed with a third gear 27, and the third gear 27 is meshed with the speed reducing gear set 24. When the clutch gear 22 is turned to mesh with the speed reducing gear set 24, the drive motor unit 11 forms a transmission connection with the device. At this time, the drive motor unit 11 is driven to start, so that the first weight 3 can be lifted up, and due to the effect of the speed reducing gear set 24, the weight 3 can be lowered. The rotation speed of the first gear 12 increases its torque, providing sufficient guarantee for lifting the first weight 3; when the clutch gear 22 is turned to engage with the speed-increasing gear set 23, the generator motor unit 10 forms a transmission connection with the device, and the first weight 3 is released at this time, the first weight 3 sinks, and the float 4 and the second weight 5 rise, driving the generator motor unit 10 to rotate, thereby achieving the function of power generation. Due to the resistance of the seawater itself, the sinking speed of the first weight 3 and the rising speed of the float 4 and the second weight 5 are relatively slow. The speed-increasing gear set 23 is used to increase the rotation speed of the generator motor unit 10 to meet the speed requirement for power generation. In actual applications, gear sets with different tooth ratios can be configured according to the actual required power generation and power generation efficiency.

[0031] The marine platform 1 is provided with a weight launching area 13 and a floating body launching area 14 corresponding to the first weight 3 and the floating body 4. A movable load-bearing plate 15 for placing the first weight 3 is installed on the weight launching area 13, and an elastic edging 16 is installed on the edge of the floating body launching area 14.

[0032] The heavy object launching area 13 may also be rectangular, and the load-bearing plate 15 may be translated along the length direction on the heavy object launching area 13. When the first heavy object 3 needs to be placed, the load-bearing plate 15 may be moved directly below the first heavy object 3. When the first heavy object 3 needs to be launched into the water, the load-bearing plate 15 may be removed from the heavy object launching area 13. In addition, the load-bearing plate 15 may be composed of two suspension bridges. When the first heavy object 3 needs to be placed, the two suspension bridges are lowered, and the first heavy object 3 is placed on the suspension bridges. The structure is simple and suitable for the construction of large-scale projects. In addition, conventional methods such as a crane may be used to move the first heavy object 3 from above the heavy object launching area 13 to other positions of the offshore platform for placement.

[0033] In this embodiment, the floating body launching area 14 is a circular hole that can accommodate the floating body 4 to pass freely, and the elastic edging 16 is wrapped in the circular hole to protect the floating body 4 from being damaged by the equipment on the marine platform when passing up and down the marine platform.

[0034] A groove 17 having an arc shape similar to that of the lower end of the first weight 3 is provided in the middle of the load-bearing plate 15 . The lower end of the first weight 3 is placed on the groove 17 , and an elastic buffer pad 18 is placed between the first weight 3 and the groove 17 .

[0035] When the first weight 3 is placed in the groove 17, it is ensured that the first weight 3 will not slide, thereby further improving the stability and safety of the system operation. At this time, the first weight 3 has been fixed and placed, and the transmission cable 2 of the entire system is also stopped, thereby synchronously limiting the positions of the float 4 and the second weight 5. At this time, the float 4 and the second weight 5 are suspended in the sea through the transmission cable 2, or the float 4 and the second weight 5 sink to the bottom of the sea. Since the second weight 5 and the float 4 themselves have increased weight, the overall shape of the second weight 5 and the float 4 can adopt a streamlined structure, which further reduces the impact of external forces (such as forces caused by ocean currents or other marine environments), avoids the impact of excessive swings on the marine platform, and further improves the safety and stability of the entire system.

[0036] When the first weight 3, the floating body 4 and the second weight 5 rise or sink, the upper end of the floating body 4 is pulled by the transmission cable 2 during this process, and the lower end of the floating body 4 is hung by the second weight 5. The floating body 4 can move vertically and will move along the transmission cable 2, thereby effectively avoiding the possibility of the floating body 4 and the second weight 5 rising and colliding with the marine platform 1.

[0037] The upper and lower ends of the first weight 3 and the upper end of the float 4 are streamlined structures, such as a streamlined bullet shape, to ensure that the flow resistance can be minimized when it moves in the sea water, and it can enter the stage of uniform motion at a faster speed and generate electricity. When the float rises, it accelerates at the beginning, but as the flow resistance of the float increases, the buoyancy, its own gravity and flow resistance eventually reach a balance and turn into uniform motion, which is more suitable for power generation and can also more effectively utilize the buoyancy potential energy for energy conversion.

[0038] In this system, a flywheel energy storage system can be connected in series. When the rising speed of the floating body 4 fluctuates, the flywheel energy storage system can absorb or release energy to maintain a relatively stable speed of the entire system, thereby ensuring that the floating body 4 moves at a uniform speed, further improving the stability of power generation.

[0039] The middle section of the first weight 3 is cylindrical, and according to different weight balancing requirements, it can be achieved by increasing or decreasing the height of the cylindrical part.

[0040] The second weight 5 is composed of a plurality of weight components, and the weight components are evenly distributed on the outer side of the lower end of the floating body 4 .

[0041] The weight assembly includes a support plate 28 fixed to the bottom of the floating body 4, a mounting frame 19 with an opening at the lower end is installed at the lower end of the support plate 28 (welding or other connection methods), and the mounting frame 19 is installed with a support leg 21 reset by a spring 20. In the initial state, the support leg 21 is extended out of the mounting frame 19. Only when the second weight 5 contacts the seabed, the support leg 21 will be retracted into the mounting frame 19, and the spring 20 will be further compressed. When the second weight 5 leaves the seabed, the spring 20 will push the support leg 21 out again to reset. At this time, the total length of the mounting frame 19 and the support leg 21 is the longest (the length of the mounting frame 19 will not change, and the support leg 21 will be extended and retracted in the mounting frame 19, thereby changing the total length of the mounting frame 19 and the support leg 21). A limiting mechanism (belonging to the prior art) is provided between the support leg 21 and the mounting frame 19 to prevent the support leg 21 from completely detaching from the mounting frame 19.

[0042] When the floating body 4 sinks to the seabed, under the action of gravity, it can be pressed into different lengths according to the terrain. Finally, the support legs 21 can adapt to the seabed with complex terrain, and can keep the floating body 4 stable and fixed on the seabed to the greatest extent (such as Figure 5 As shown in the figure, B is a schematic diagram of a complex seabed), when the spring 20 is compressed to the limit, that is, when the support leg 21 and the mounting frame 19 are shortened to the shortest length, the end of the support leg 21 still exceeds the lower surface of the floating body 4, that is, the floating body 4 will not contact the reefs on the seabed, etc., avoiding collision with the floating body 4 and causing damage.

[0043] Elastic material is added to the end of the supporting leg 21 to increase friction when falling on the seabed, thereby further improving the stability and safety of the floating body 4 when sinking to the seabed.

[0044] The complete energy storage steps of the method of the present invention are: S1: The initial state is that the first weight is sunk on the seabed or hanging in the seawater and is located at a low point, the floating body floats on the sea surface, the clutch speed change gearbox is adjusted to become a reduction gearbox, and is connected to the drive motor unit 11 by transmission, and the drive motor unit 11 is driven by the power supply / network to pull the first weight 3 to a high point (this process is carried out when the electricity price is relatively cheap, so as to store energy at the lowest cost), the second weight 5 drags the floating body 4 down to a low point (also sunk on the seabed or hanging in the seawater), and is initially fixed (when the first weight 3 is pulled to a high point and in the initial state, the floating body 4 and the second weight 5 are located at a high point on the sea, which can be the same height or different heights, which is related to the actual engineering construction); S2: moving the load-bearing plate 15 to cover the weight launching area 13, and driving the driving motor unit 11 in reverse to slowly lower the first weight 3 until the first weight 3 is placed in the groove 17; The complete energy release steps of the method of the present invention are: A1: The driving motor unit 11 drives the first weight 3 to be lifted and completely removed from the groove 17 and initially fixed; A2: Remove the load-bearing plate 15 from the heavy object launching area 13; A3: Adjust the clutch speed change gearbox to make it an acceleration gearbox and connect it to the generator motor unit 10; A4: Release the first weight 3, and the transmission cable 2 is tightened by the first weight 3 and the second weight 5 of equal weight, and the pulling forces on the transmission cable 2 offset each other, the floating body 4 rises, and drives the clutch speed change gear box through the transmission cable 2, thereby driving the generator motor unit 10 to rotate and generate electricity.

[0045] In the present invention, during the energy storage process, the first weight 3 is pulled from the low point under the sea to the surface of the sea by electric energy. As the first weight 3 moves, the floating body 4 and the second weight 5 connected by the pulley block and the transmission cable 2 sink accordingly (in this process, the first weight 3 can sink at the same speed as the floating body 4 and the second weight 5, that is, the transmission cable 2 is tightened at this time, or the rising speed of the first weight 3 is greater than the sinking speed of the floating body 4 and the second weight 5, and the transmission cable 2 is relaxed at this time, until the first weight 3, the floating body 4 and the second weight 5 stop When moving, the transmission cable 2 is tightened); during the discharge process, the first weight 3 is released. The function of the first weight 3 and the second weight 5 is to always tighten the transmission cable 2 and achieve system balance through the transmission cable 2 and the pulley group. Under this balance (the movement of the first weight 3 and the second weight 5 will not cause negative work in theory. In fact, the rotation of the pulley group consumes a certain amount of energy, but it can be ignored compared with the energy stored in the entire system), the floating body 4 begins to rise, thereby driving the generator motor unit 10 to rotate and generate electricity, thereby realizing buoyancy work.

[0046] In the present system, the motor unit, pulley block, etc. are all installed on the marine platform 1, and only the first weight 3, floating body 4, second weight 5 and the corresponding transmission cable 2 will sink to the bottom of the sea, and the first weight 3, floating body 4 and second weight 5 only need to be suspended on the marine platform 1 through the transmission cable 2, without the need for additional fixation, which can greatly simplify the engineering workload. At the same time, compared with equipment such as motors and pulleys, structures such as weights and floating bodies can be better treated for corrosion resistance, and even if the weights and floating bodies are corroded and damaged within a certain range, they can still be used normally. If equipment such as motors and pulleys are in contact with seawater for a long time, they require high frequency of maintenance, and their service life will also be greatly reduced.

[0047] This system allows the floating body 4 to sink to any specified water depth, that is, when the floating body 4 sinks to the limit, it can be directly in contact with the seabed, or it can be out of contact with the seabed, or even far away from the seabed (for example, if the seabed depth is 200 meters, when the floating body 4 sinks to the limit, it is 150 meters away from the seabed).

[0048] When the float 4 breaks through the water surface, its own drainage volume gradually decreases, and then its buoyancy gradually decreases, until the float of the float 4 itself is balanced with its own gravity, and the entire system will reach a final equilibrium state, that is, the first weight 3 is balanced with the second weight 5, and the float of the float 4 itself is balanced with its own gravity. This is the daily stable state of the system, and at this time, the float 4 is located in the float launching area 14, and will not drift away from the ocean platform.

[0049] In addition, when the float 4 starts to break through the water surface and ends, the buoyancy of the float 4 gradually decreases, that is, the pulling force of the float 4 and the second weight 5 on the transmission cable 2 as a whole increases, and the pulling force transmitted to the first weight 3 through the transmission cable 2 increases, thereby dragging the first weight 3 to decelerate until it stops, that is, the float 4 plays a role of buffering and deceleration from the beginning to the end of breaking through the water surface, further improving the stability and safety of the system.

[0050] The working cycle of the entire system is based on the balancing effect between the first weight 3 and the second weight 5. On the one hand, this system can be understood as a buoyancy energy storage system, and the first weight 3 and the second weight 5 serve as counterweights to assist in tightening the transmission cable 2, and the release and storage of energy are achieved by the rise and fall of the float 4. On the other hand, this system can be understood as a gravity energy storage system, and the second weight 5 and the float 4 are almost balanced in buoyancy and gravity, that is, the second weight 5 and the float 4 as a whole can be regarded as a small-mass counterweight block, which assists in tightening the transmission cable 2, and the storage and release of energy are achieved by the rise and fall of the first weight 3. In view of the fact that this system can understand its energy storage process from the two perspectives of buoyancy and gravity, and both understandings are reasonable and scientific, we call this set of methods and devices a buoyancy-gravity composite energy storage method and device.

[0051] In the present invention, the first weight 3 and the second weight 5 are made of high-density materials such as lead, cement, concrete, iron, etc., which can achieve a larger counterweight with a smaller volume, making the project more convenient. For example, when a weight of 50 tons is required, the density of lead reaches 11.34 tons / m 3 , only 4.4m is needed 3 At the same time, since the buoyancy of the float 4 is slightly smaller than the gravity of the second weight 5, a float with a buoyancy of 45 tons can be configured.

[0052] Since the pressure of seawater on the floating body 4 is different at different depths, for example, at a depth of 200 meters under the sea, according to P=ρgh, it can be known that the pressure of 200 meters of seawater on the floating body is about 2MPa, that is, the outer shell material of the floating body needs to be able to withstand a pressure of 2MPa. In actual engineering, different materials need to be selected according to the actual environment to avoid excessive requirements (such as the maximum sinking depth of the floating body 4 reaches 50 meters, that is, it reaches the seabed, and a floating body that can be used at a depth of 200 meters in the ocean is used), which leads to increased engineering costs.

[0053] In addition, according to the above example, the selection requirements of the transmission cable 2 of this system are also very important. It must meet the requirements of wear resistance, corrosion resistance (especially seawater corrosion resistance), and be able to withstand the pulling of 50 tons of weight. In the existing technology, phosphate-coated steel wire ropes have excellent performance in wear resistance and corrosion resistance, especially manganese-based phosphate-coated steel wire ropes, which have greatly improved wear resistance and corrosion resistance. For a weight of 50 tons, we need to calculate the required rope diameter (that is, the diameter of the transmission cable 2), and a single steel wire rope needs to bear at least 50 tons.

[0054] The safety factor (SF) can be calculated using the following formula: SF = minimum breaking load / actual load.

[0055] In actual engineering, the safety factor needs to be greater than or equal to 6. Therefore, if a weight of 50 tons needs to be pulled up, the minimum breaking load of the rope should be 300 tons. In this case, 8×K41WS structural steel core wire rope is needed, with a nominal tensile strength of 1870MPa and a minimum breaking force of 314 tons. The rope weight based on this material is 2030kg / 100m, and a 200-meter-long rope is approximately 4.06 tons.

[0056] Due to the heavy weight of the rope, the actual number of pulleys may be much larger than the number shown in the figure. The figure is only for demonstration of the method.

[0057] In the present invention, the term "plurality" means two or more than two, unless otherwise clearly defined. The term "and / or" used herein includes any and all combinations of one or more of the related listed items. The terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "connect" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0058] It should be noted that when an element is referred to as being "assembled on", "installed on", "fixed on" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0059] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0060] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for buoyancy-gravity composite energy storage for offshore use, characterized in that The method is: establish a mobile or fixed marine platform at sea, install a pulley block and a motor unit on the marine platform, pass a transmission cable linked to the motor unit through the pulley block, fix a first weight at one end of the transmission cable, fix a floating body at the other end, and install a second weight with the same weight as the first weight at the bottom of the floating body. When the floating body and the second weight are completely immersed in seawater, the buoyancy of the floating body is slightly less than the weight of the second weight. In the initial state, the first weight sinks to the seabed or hangs in the seawater at a low point, and the floating body Floating on the sea surface, when storing energy, electricity drives the motor unit to lift the first weight to a high point and fix it, and the second weight drags the floating body to sink to store energy. When releasing energy, the first weight is released, and the transmission cable is tightened by the first weight and the second weight of equal weight, and the pulling forces on the transmission cable offset each other, the floating body rises back to the sea surface, and the first weight sinks back to a low point. During the rising process of the floating body, the transmission cable drives the motor unit to generate electricity, and the buoyancy-gravity composite power storage is realized through the energy storage and release cycle.

2. A buoyancy-gravity composite energy storage device for use at sea, characterized in that: The invention comprises a mobile or fixed marine platform (1) established at sea, a pulley block and a motor unit installed on the marine platform (1), a transmission cable (2) linked to the motor unit passing through the pulley block, a first weight (3) fixed at one end of the transmission cable (2), a floating body (4) fixed at the other end, and a second weight (5) having the same weight as the first weight installed at the bottom of the floating body (4), when the floating body (4) and the second weight (5) are completely immersed in seawater, the buoyancy of the floating body (4) is slightly smaller than the weight of the second weight (5).

3. The buoyancy-gravity composite energy storage device for use at sea according to claim 2 is characterized in that The pulley block comprises a first pulley (6), a second pulley (7), a third pulley (8), and a fourth pulley (9); the third pulley (8) and the fourth pulley (9) are installed at the same height, and the second pulley (7) has the lowest installation height; the transmission cable (2) passes through the first pulley (6), the second pulley (7), the third pulley (8), and the fourth pulley (9) in sequence; and the second pulley (7) is transmission-connected to the motor unit.

4. The buoyancy-gravity composite energy storage device for use at sea according to claim 3 is characterized in that The motor unit comprises a generator motor unit (10) and a drive motor unit (11); the generator motor unit (10) and the drive motor unit (11) are connected to a first gear (12) via a clutch transmission gearbox; the first gear (12) rotates synchronously with the second pulley (7).

5. The buoyancy-gravity composite energy storage device for use at sea according to claim 2, characterized in that The offshore platform (1) is provided with a weight launching area (13) and a floating body launching area (14) corresponding to the first weight (3) and the floating body (4); a movable load-bearing plate (15) for placing the first weight (3) is installed on the weight launching area (13); and an elastic edging (16) is installed on the edge of the floating body launching area (14).

6. The buoyancy-gravity composite energy storage device for use at sea according to claim 5, characterized in that A groove (17) similar to the lower end of the first weight (3) is provided in the middle of the load-bearing plate (15); the lower end of the first weight (3) is placed on the groove (17); and an elastic buffer pad (18) is placed between the first weight (3) and the groove (17).

7. The buoyancy-gravity composite energy storage device for use at sea according to claim 6, characterized in that The upper and lower ends of the first weight (3) and the upper end of the floating body (4) are both streamlined structures.

8. The buoyancy-gravity composite energy storage device for use at sea according to claim 2, characterized in that The second weight (5) is composed of a plurality of weight components, and the weight components are evenly distributed on the outer side of the lower end of the floating body (4).

9. The buoyancy-gravity composite energy storage device for use at sea according to claim 8, characterized in that The weight assembly comprises a support plate (28) fixed to the bottom of the floating body (4), a mounting frame (19) with an open lower end is mounted at the lower end of the support plate (28), and a support leg (21) reset by a spring (20) is mounted on the mounting frame (19).

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