Hydropower station combined mechanical gravity energy storage system and design method

Abstract

The invention relates to a hydropower station combined mechanical gravity energy storage system and a design method.The hydropower station combined mechanical gravity energy storage system comprises a pumped storage power station and a mechanical gravity energy storage system, and the pumped storage power station comprises an upper reservoir, a lower reservoir and an underground powerhouse; the upper reservoir and the lower reservoir are located on the upstream side and the downstream side of the dam body respectively, a preset height difference exists between the upper reservoir and the lower reservoir, the upper reservoir and the lower reservoir communicate with the underground powerhouse through the diversion tunnel, and the underground powerhouse is located in the dam body; the mechanical gravity energy storage system comprises rotary lifting equipment, a feeding bin, a discharging bin and a gravity block, the rotary lifting equipment is arranged at the top of the dam body, the feeding bin and the discharging bin are arranged on the dam body, and a preset height difference exists between the feeding bin and the discharging bin; and the rotary hoisting equipment can convey the gravity block to the upper material bin and the lower material bin back and forth.

Description

Technical Field

[0001] The present application relates to the technical field of pumped storage power stations, and in particular to a hydropower station combined mechanical gravity energy storage system and a design method. Background Art

[0002] With the proposal of the goal of "carbon peak and carbon neutrality", in order to protect the ecological environment and cope with the increasing depletion of non-renewable resources such as oil, new energy sources such as wind power generation, photovoltaic power generation, solar power generation and wave power generation are widely used. However, the power generation of these new energy sources is random and intermittent, which brings certain difficulties to the power balance, stability and peak regulation of the power grid. In order to ensure the stable and safe operation of the power grid, energy storage systems such as pumped storage power stations and mechanical gravity energy storage are the most effective and convenient measures. Pumped storage power stations are mainly composed of upper reservoirs and lower reservoirs, which have a high height difference; gravity energy storage is a new domestic energy storage technology. One of the difficulties in its construction is that it needs to utilize a very high height difference, but there is no engineering case of a hydropower station combined with a mechanical gravity energy storage system in China. Summary of the invention

[0003] The first aspect of the present application provides a hydropower station combined with a mechanical gravity energy storage system, which combines a pumped-storage power station with a mechanical gravity energy storage system, can greatly reduce the construction cost of the mechanical gravity energy storage system, and serve as a backup power source for the power station to increase the total peak power generation capacity.

[0004] The hydropower station combined mechanical gravity energy storage system provided in the first aspect of the present application includes a pumped-storage power station and a mechanical gravity energy storage system, the pumped-storage power station includes an upper reservoir, a lower reservoir and an underground plant, the upper reservoir and the lower reservoir are respectively located on the upstream side and the downstream side of the dam body, and there is a preset height difference between the upper reservoir and the lower reservoir, the upper reservoir and the lower reservoir are respectively connected to the underground plant through a water diversion tunnel, and the underground plant is located inside the dam body; the mechanical gravity energy storage system includes a rotary lifting device, an upper silo, a lower silo and a gravity block, the rotary lifting device is arranged on the top of the dam body, the upper silo and the lower silo are arranged on the dam body, and there is a preset height difference between the upper silo and the lower silo, and the rotary lifting device can transport the gravity block back and forth between the upper silo and the lower silo.

[0005] In addition, the hydropower station combined mechanical gravity energy storage system provided in this application may also have the following additional technical features:

[0006] In an optional solution, the pumped storage power station and the mechanical gravity energy storage system share underground cables, and the underground cables are electrically connected to the power transmission and utilization substation and transmission lines arranged on the dam body.

[0007] In an optional scheme, the rotating lifting equipment includes a first lifting arm, a second lifting arm, a luffing trolley, a hook, a generator set, a rotating device and a standard section; the standard section is fixedly set on the dam body through a foundation pedestal, the first lifting arm and the second lifting arm are set on the upper part of the standard section through the rotating device, the generator set is set on the standard section, the luffing trolley is slidably set on the tracks of the first lifting arm and the second lifting arm respectively, and the luffing trolley is connected to the hook through a pulley block and a wire rope.

[0008] In an optional solution, the rotating lifting equipment also includes an intelligent cab, which is arranged at the upper part of the standard section. An intelligent driving system is installed in the intelligent cab, and the intelligent driving system includes an automatic positioning module, an automatic take-off and landing module, a remote control module and a fault diagnosis module.

[0009] In an optional scheme, the upper silo and the lower silo are storage-type silos, slide rails are provided inside the storage-type silos, a skylight that can be opened and closed is provided on the top of the storage-type silo, and drainage holes are provided on the lower side wall of the storage-type silo; the gravity block is placed inside the storage-type silo.

[0010] In an optional solution, the gravity block is a concrete block or a block made of corrosion-resistant and environmentally friendly materials, and a positioning chip is arranged inside the gravity block.

[0011] In an optional solution, the hydropower station combined with the mechanical gravity energy storage system has an energy storage stage and an energy release stage during operation. During the energy storage stage, the pumped storage power station uses excess electric energy to pump water from the lower reservoir to the upper reservoir, and the mechanical gravity energy storage system uses excess electric energy to drive the rotary lifting device, and the rotary lifting device transports the gravity block in the lower silo to the upper silo;

[0012] During the energy release phase, the water storage power station converts the gravitational potential energy of water into electrical energy, and the mechanical gravity energy storage system converts the gravitational potential energy of the gravity block into electrical energy.

[0013] The second aspect of the present application provides a design method for a hydropower station combined mechanical gravity energy storage system, the design method is used to design the hydropower station combined mechanical gravity energy storage system provided in the first aspect, the design method comprises the following steps:

[0014] According to the scale of the pumped storage power station, the mass energy storage density is taken into consideration. The greater the mass energy storage density, the smaller the volume and mass of the mechanical gravity energy storage system required to store the same amount of electrical energy. Combined with the elevation of the main body of the dam, the lifting height of the rotating lifting equipment on the top of the main body of the dam, the location of the loading and unloading yards, and the size and number of gravity blocks are planned;

[0015] An efficiency model is established to determine the configuration and parameter combination of the mechanical gravity energy storage system.

[0016] In an alternative approach, the efficiency model is developed by including:

[0017] The mechanical gravity energy storage system converts electrical energy into gravitational potential energy for storage during the energy storage phase, and converts gravitational potential energy into electrical energy by rotating the generator set of the lifting equipment during the energy release phase. The efficiency of the entire system is expressed as:

[0018] η=η EG ×η ES ;

[0019] For gravity energy storage, the mass energy storage density is expressed as: U m =mgx; volume energy storage density is: Among them, m is the mass of a single gravity block, x is the displacement of the gravity block, and V is the volume of the gravity block. From the above formula, it can be seen that the energy storage density is related to the displacement during mechanical gravity energy storage. The high altitude of the pumped storage power station has a natural advantage. The energy storage density can be used to measure the mass of the mechanical gravity energy storage device and the size of the space it occupies;

[0020] The main sources of loss of the mechanical gravity energy storage system in the process of lifting the gravity block and transporting it to the loading or unloading yard are two aspects. On the one hand, the drag coefficient caused by air resistance when the gravity block is lifted / lowered, and on the other hand, the friction loss caused by friction; wherein the drag loss is expressed as:

[0021]

[0022] Where A is the windward area of ​​the gravity block, ρ is the air density, and C w is the air resistance coefficient, v(t) represents the rising / falling speed, and t represents the time;

[0023] The friction loss includes the friction between the variable-length trolley and the track during the translation of the gravity block, the rotational friction of the rotating device, and the friction of the conveying tracks of the loading and unloading yards. The magnitude of the friction force in the friction loss is positively correlated with the mass of the gravity block, so the total friction loss is expressed as:

[0024] E f =E f1 +E f2 +Ef3 ;

[0025] E f3 =μ2mgx;

[0026] Where γ, μ and μ2 represent the coefficients of correlation between friction and the mass of the gravity block, which are relevant to actual engineering projects; v′(t) represents the moving speed of the variable-length trolley; ω(t) is the angular velocity of rotation; r is the rotation radius; and x is the distance that the object is transported by the transport track.

[0027] In an optional solution, the calculation of energy storage efficiency and power generation efficiency is also included when establishing the efficiency model;

[0028] In the energy storage stage, the mechanical gravity energy storage system drives the gravity block to rise, and the gravity block overcomes air resistance to do work. The gravity block needs to overcome friction to do work when it reaches the corresponding position of the loading yard. Considering the motor loss and the bidirectional substation loss, the energy storage efficiency is expressed as:

[0029]

[0030] In the formula, E q represents the energy consumed by the gravity block to rise, η G is the efficiency of the electric generator, η inv represents the bidirectional substation efficiency;

[0031] During the energy release stage, the mechanical gravity energy storage system uses the gravity block's own gravity as a power source, overcomes wind resistance and performs work during the descent process, and the luffing trolley overcomes friction to translate the gravity block from the loading yard to above the unloading yard. During the descent process, the gravity potential energy is converted into kinetic energy, most of which is converted into electrical energy through the generator set and supplied to users through the bidirectional substation and transmission line. The power generation efficiency is:

[0032]

[0033] In the formula, E q ′ represents the energy released when the gravity block descends.

[0034] The beneficial effects of this application are:

[0035] The hydropower station combined with the mechanical gravity energy storage system in this application utilizes the characteristics of the pumped-storage power station with high-elevation geographical conditions, and builds the mechanical gravity energy storage system on the main body of the dam, thereby reducing the construction cost of the mechanical gravity energy storage system; during the low-peak period of electricity consumption, the mechanical gravity energy storage system can effectively store electricity together with the pumped-storage power station. In addition, the mechanical gravity energy storage system can transport workers or large construction materials when there is a special need, and provide assistance for the construction and maintenance of the power station; it can also be used as a backup power source for pumped-storage hydropower stations, which is cleaner than the traditional use of diesel engines as a backup power source. This system can help pumped-storage power stations increase their total peak power generation and increase the economy of the power station. The mechanical gravity energy storage system can generate electricity during the energy storage and release stages, which can make up for the energy loss caused by the operation of the energy storage system.

[0036] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic structural diagram of a hydropower station combined with mechanical gravity energy storage in a specific embodiment of the present application;

[0038] Figure 2 A schematic diagram of the structure of the rotary lifting device provided in the present application in a specific embodiment;

[0039] Figure 3 A schematic diagram of the structure of a storage-type silo in a specific embodiment provided in this application.

[0040] Figure numerals: upper reservoir 11, lower reservoir 12, underground powerhouse 13, diversion tunnel 14, upper silo 15, lower silo 16, gravity block 17, dam body 2, rotating lifting equipment 3, first lifting arm 31, second lifting arm 32, luffing trolley 33, hook 34, generator set 35, rotating device 36, standard section 37, foundation pedestal 38, intelligent cab 39, underground cable 4, power transmission and utilization substation 5, transmission line 6, storage silo 7, slide rail 71, skylight 72, drainage hole 73.

[0041] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application. DETAILED DESCRIPTION

[0042] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0043] It should be clear that the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other technical solutions obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0044] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0045] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0046] It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described at the angles shown in the accompanying drawings and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0047] like Figure 1-3 As shown, the first aspect of an embodiment of the present application provides a hydropower station combined with a mechanical gravity energy storage system, which includes a pumped-storage power station and a mechanical gravity energy storage system. The mechanical gravity energy storage system is installed in the upper reservoir of the pumped-storage power station as a backup power source for the power station. It is cleaner than traditional diesel engines and assists the power station in peak load regulation and frequency regulation.

[0048] Specifically, the pumped-storage power station includes an upper reservoir 11, a lower reservoir 12 and an underground plant 13. The upper reservoir 11 and the lower reservoir 12 are respectively located on the upstream and downstream sides of the dam body 2, and there is a preset height difference between the upper reservoir 11 and the lower reservoir 12. The upper reservoir 11 and the lower reservoir 12 are respectively connected to the underground plant 13 through a water diversion tunnel 14, and the underground plant 13 is located inside the dam body 2; the mechanical gravity energy storage system includes a rotating lifting device 3, an upper silo 15, a lower silo 16 and a gravity block 17. The rotating lifting device 3 is arranged on the top of the dam body 2, the upper silo 15 and the lower silo 16 are arranged on the dam body 2, and there is a preset height difference between the upper silo 15 and the lower silo 16, and the rotating lifting device 3 can transport the gravity block 17 back and forth between the upper silo 15 and the lower silo 16.

[0049] The upper reservoir 11 of the pumped-storage power station is an upper reservoir 11 of a power station developed by utilizing natural landforms, newly excavated and constructed, or an upper reservoir 12 of a pumped-storage power station developed by utilizing natural landforms, newly excavated and constructed, or an upper reservoir 12 of a pumped-storage power station developed by utilizing natural landforms, newly excavated and constructed, and the water in the upper reservoir is led into the underground plant 13 through a water diversion tunnel 14, and the hydro-turbine generator set in the underground plant 13 generates electricity.

[0050] The hydropower station combined with the mechanical gravity energy storage system in this embodiment utilizes the characteristics of the pumped-storage power station with high-elevation geographical conditions, and builds the mechanical gravity energy storage system in the dam body 2, thereby reducing the construction cost of the mechanical gravity energy storage system; during the low-peak period of electricity consumption, the mechanical gravity energy storage system can effectively store electricity together with the pumped-storage power station. In addition, the mechanical gravity energy storage system can transport workers or large construction materials when there is a special need, and provide assistance for the construction and maintenance of the power station; in addition, it can also be used as a backup power source for the pumped-storage hydropower station, which is cleaner than the traditional use of diesel engines as a backup power source. This system can help the pumped-storage power station increase the total peak power generation and increase the economy of the power station. The mechanical gravity energy storage system can generate electricity in both the storage and release stages, which can make up for the power loss caused by the operation of the energy storage system.

[0051] like Figure 1 As shown, in a specific embodiment, the pumped storage power station and the mechanical gravity energy storage system share an underground cable 4, and the underground cable 4 is electrically connected to a power transmission and utilization substation 5 and a transmission line 6 arranged on the dam body 2.

[0052] like Figure 1-2As shown, in a specific embodiment, the rotary hoisting device 3 includes a first lifting arm 31, a second lifting arm 32, a luffing trolley 33, a hook 34, a generator set 35, a rotating device 36 and a standard section 37; the standard section 37 is fixedly arranged on the dam body 2 through a foundation pedestal 38, the first lifting arm 31 and the second lifting arm 32 are arranged on the upper part of the standard section 37 through a rotating device 36, the generator set 35 is arranged on the standard section 37, the luffing trolley 33 is slidably arranged on the tracks of the first lifting arm 31 and the second lifting arm 32, and the luffing trolley 33 is connected to the hook 34 through a pulley block and a wire rope. The luffing trolley 33 can realize the translation of the heavy object, and the intelligent cab 39 automatically adjusts the position of the luffing trolley 33 according to the force condition to ensure the balance of the device.

[0053] In addition, the rotary lifting device 3 also includes an intelligent cab 39, which is arranged on the upper part of the standard section 37. An intelligent driving system is arranged in the intelligent cab 39. The intelligent driving system can monitor the operation safety data of the rotary lifting device 3 and perform fault diagnosis through the monitoring data, including PLC data such as the force, vibration, noise, etc. of the boom or other sensor data, and can realize remote control, automatic positioning of the gravity block 17, and automatic lifting and lowering of the gravity block 17 according to real-time requirements. The intelligent driving system includes an automatic positioning module, an automatic lifting and lowering module, a remote control module, and a fault diagnosis module.

[0054] The rotating lifting device 3 in this embodiment can be a double-boom tower crane. It should be noted that although a double-boom tower crane is used as the main lifting device of the mechanical gravity energy storage system, other lifting devices such as traditional tower cranes or tower cranes with more boom designs are not excluded as main equipment, and this article does not make specific limitations on this.

[0055] like Figure 3 As shown, in a specific embodiment, the upper bin 15 and the lower bin 16 are storage bins 7, a slide rail 71 is provided inside the storage bin 7, a skylight 72 that can be opened and closed is provided on the top of the storage bin 7, and a drainage hole 73 is provided on the lower side wall of the storage bin 7; the gravity block 17 is placed in a vertical array inside the storage bin 7. The drainage hole 73 can effectively prevent water from accumulating in the storage bin 7 during the rainy season, and the upper bin 15 and the lower bin 16 can also serve as temporary warehouses for stacking construction materials or necessary living materials. In addition, the gravity block 17 is made of concrete blocks or environmentally friendly materials that have good corrosion resistance and can be recycled in a humid environment. A positioning chip is pre-embedded in the gravity block 17, which is convenient for the intelligent cab 39 to locate the position of the gravity block 17 and perform operations such as picking up, transporting and placing. If there is a special need, the gravity block 17 can be replaced by staff or construction materials to provide assistance for power station construction and maintenance.

[0056] The hydropower station combined with the mechanical gravity energy storage system has an energy storage stage and an energy release stage during operation. During the energy storage stage, the pumped storage power station uses excess electric energy to pump water from the lower reservoir 12 to the upper reservoir 11, and the mechanical gravity energy storage system uses excess electric energy to drive the rotating lifting device 3, and the rotating lifting device 3 transports the gravity block 17 in the lower bin 16 to the upper bin 15; during the energy release stage, the water storage power station converts the gravitational potential energy of water into electrical energy, and the mechanical gravity energy storage system converts the gravitational potential energy of the gravity block 17 into electrical energy.

[0057] Specifically, the energy storage process is as follows: at night, which is a period of low electricity demand, the pumped storage power station uses excess electricity to pump water from the lower reservoir 12 to the upper reservoir 11, and at this time the electricity is converted into the gravitational potential energy of water for storage. The mechanical gravity energy storage system is also driven by excess electric energy. The slide rail 71 of the lower bin 16 moves the gravity block 17 to the position of the skylight 72. The automatic driving room automatically positions the gravity block 17, operates the second crane arm 32 to lower the hook 34 to lift the gravity block 17, and the variable-length trolley 33 simultaneously performs the operation of balancing the translation of the gravity block 17. The rotating device 36 rotates the second crane arm 32 to the upper bin 15 while the first crane arm 31 rotates to the lower bin 16, lifts the gravity block 17 and translates the gravity block 17 position through the variable-length trolley 33 to balance the device. At this time, the variable-length trolley 33 of the second crane arm 32 moves the gravity block 17 to the top of the upper bin 15, and relies on the gravity of the gravity block 17 to be lowered into the bin, completing the conversion of excess electric energy into gravitational potential energy storage. Among them, the gravity blocks 17 in the upper and lower bins 16 are placed in a vertical array. When a certain height is reached, the slide rail 71 transports the gravity blocks 17 into the bin for storage. During the descent of the gravity block 17 , the generator set 35 is driven to convert a small part of the gravitational potential energy into electrical energy, thereby compensating for part of the electrical energy loss.

[0058] Energy release process: When the power demand reaches the peak period, the pumped storage power station will open the gate of the upper reservoir 11 to release water, and the gravitational potential energy of the water will be converted into electrical energy; the slide rail 71 of the upper bin 15 of the mechanical gravity energy storage system will move the gravity block 17 to the position of the skylight 72, the automatic driving room will automatically position the gravity block 17 and control the first crane arm 31 to lift, the variable-length trolley 33 will synchronously operate the translation of the gravity block 17 balance device, and the rotating device 36 will rotate the gravity block 17 lifted by the first crane arm 31 to the top of the skylight 72 of the lower bin 16 and place it, realizing the conversion of gravitational potential energy into electrical energy. The operation mode of the energy release process is opposite to that of the energy storage process. The electricity generated by both is transmitted to the substation and the transmission line 6 through the underground cable 4 for users to use. At this time, the mechanical gravity energy storage device also plays a role in peak regulation and frequency regulation.

[0059] A second aspect of the embodiments of the present application provides a design method for a hydropower station combined with a mechanical gravity energy storage system. The design method is used to design the hydropower station combined with a mechanical gravity energy storage system in the embodiment of the first aspect. The design method comprises the following steps:

[0060] According to the scale of the pumped storage power station, consider the mass energy storage density, that is, the amount of energy stored per unit volume or weight. The greater the mass energy storage density, the smaller the volume and mass of the mechanical gravity energy storage system required to store the same amount of electrical energy. Combined with the elevation of the dam body, plan the lifting height of the rotating lifting equipment on the top of the dam body, the location of the loading and unloading yards, and the size and number of gravity blocks;

[0061] Establish an efficiency model to determine the optimal configuration and parameter combination of the mechanical gravity energy storage system:

[0062] The mechanical gravity energy storage system converts electrical energy into gravitational potential energy for storage during the energy storage stage, and converts gravitational potential energy into electrical energy through the generator set of the rotating lifting equipment during the energy release stage. The efficiency of the entire system is expressed as:

[0063] η=η EG ×η ES ;

[0064] For gravity energy storage, the mass energy storage density is expressed as: U m =mgx; volume energy storage density is: Among them, m is the mass of a single gravity block, x is the displacement of the gravity block, and V is the volume of the gravity block. It can be seen from the above formula that the energy storage density is related to the displacement during mechanical gravity energy storage. The high altitude of the pumped storage power station has a natural advantage. The energy storage density can be used to measure the mass of the mechanical gravity energy storage device and the size of the space it occupies. Reasonable consideration can save costs and facilitate installation.

[0065] In addition, the main sources of loss in the mechanical gravity energy storage system during the process of lifting the gravity block and transporting it to the loading or unloading yard are two aspects. On the one hand, the wind resistance coefficient caused by air resistance when the gravity block is lifted / lowered, and on the other hand, the friction loss caused by friction; among them, the wind resistance loss is expressed as:

[0066]

[0067] Where A is the windward area of ​​the gravity block, ρ is the air density, and C w is the air resistance coefficient, v(t) represents the rising / falling speed, and t represents the time;

[0068] The friction loss includes the friction between the variable-length trolley and the track during the translation of the gravity block, the rotational friction of the rotating device, and the friction of the conveying tracks of the loading and unloading yards. The magnitude of the friction force in the friction loss is positively correlated with the mass of the gravity block, so the total friction loss is expressed as:

[0069] E f =E f1 +E f2 +E f3 ;

[0070] E f3 =μ2mgx;

[0071] Where γ, μ and μ2 represent the coefficients of correlation between friction and the mass of the gravity block, which are relevant to actual engineering projects; v′(t) represents the moving speed of the variable-length trolley; ω(t) is the angular velocity of rotation; r is the rotation radius; and x is the distance that the object is transported by the transport track.

[0072] In the energy storage stage, the mechanical gravity energy storage system drives the gravity block to rise. The gravity block overcomes the air resistance to do work. The gravity block needs to overcome the friction to do work when it reaches the corresponding position of the loading field. Considering the motor loss and the bidirectional substation loss, the energy storage efficiency is expressed as:

[0073]

[0074] In the formula, E q represents the energy consumed by the gravity block to rise, η G is the efficiency of the electric generator, η inv represents the bidirectional substation efficiency;

[0075] In the energy release stage, the mechanical gravity energy storage system relies on the gravity of the gravity block as the power source. During the descent, it overcomes wind resistance and does work. The luffing trolley overcomes friction and moves the gravity block from the loading yard to the top of the unloading yard. During the descent, the gravitational potential energy is converted into kinetic energy. Most of the energy is converted into electrical energy through the generator set and supplied to users through bidirectional substations and transmission lines. The power generation efficiency is:

[0076]

[0077] In the formula, E q ′ represents the energy released when the gravity block descends.

[0078] In each embodiment of the present application, a pumped-storage power station is constructed in combination with a mechanical gravity energy storage system. The mechanical gravity energy storage system can utilize the unique geographical conditions of the hydropower station to reduce construction costs; store excess electricity; assist the hydropower station in peak regulation, frequency regulation and standby; and improve the total peak power generation efficiency of the power station. When the design is completed and construction is carried out, the rotary lifting equipment of the mechanical gravity energy storage system utilizes the existing 100-meter elevation scale of the main dam of the pumped-storage power station to reduce its construction height and controllable construction costs; in addition, the foundation pedestal can be considered in the early stages of the design and construction of the pumped-storage power station, and parts can be embedded in advance to share the construction costs, reduce the difficulty of secondary development in the later stage, and have good economic efficiency.

[0079] Pumped-storage power stations use water as the energy storage medium. During the period of low electricity, the water in the lower reservoir is pumped to the upper reservoir to realize the conversion of electrical energy into water gravitational potential energy storage. It has good peak-shaving, frequency regulation, energy storage, standby and other functions. At the same time, the upper and lower reservoirs have a significant height difference; the mechanical gravity energy storage device uses concrete blocks or environmentally friendly materials that are not easily corroded in a humid environment as the energy storage medium. The pumped-storage power station can provide very favorable natural height conditions for the mechanical gravity energy storage device to effectively reduce the construction height of the device itself. At the same time, the mechanical gravity energy storage system can be embedded in advance at the beginning of the dam construction to create a solid foundation and share the construction cost, which has good economic efficiency. The excess electric energy of the pumped-storage power station is supplied to the mechanical gravity energy storage device for energy storage. The mechanical gravity energy storage device can also assist the power station in peak-shaving and frequency regulation, increase the total peak power generation power, and serve as a backup power source for the hydropower station. It is cleaner than the traditional diesel generator as a backup power source.

[0080] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A hydropower station combined mechanical gravity energy storage system, characterized in that: It includes a pumped storage power station and a mechanical gravity energy storage system, wherein the pumped storage power station includes an upper reservoir, a lower reservoir and an underground powerhouse, wherein the upper reservoir and the lower reservoir are respectively located at the upstream side and the downstream side of the dam body, and there is a preset height difference between the upper reservoir and the lower reservoir, wherein the upper reservoir and the lower reservoir are respectively connected to the underground powerhouse through a diversion tunnel, and the underground powerhouse is located inside the dam body; The mechanical gravity energy storage system includes a rotating lifting device, an upper bin, a lower bin and a gravity block. The rotating lifting device is arranged on the top of the dam body. The upper bin and the lower bin are arranged on the dam body, and there is a preset height difference between the upper bin and the lower bin. The rotating lifting device can transport the gravity block back and forth between the upper bin and the lower bin.

2. The hydropower station combined mechanical gravity energy storage system according to claim 1 is characterized in that: The pumped storage power station and the mechanical gravity energy storage system share underground cables, and the underground cables are electrically connected to the power transmission and utilization substation and the transmission line arranged on the dam body.

3. The hydropower station combined mechanical gravity energy storage system according to claim 1 or 2, characterized in that: The rotating lifting equipment includes a first lifting arm, a second lifting arm, a luffing trolley, a hook, a generator set, a rotating device and a standard section; the standard section is fixedly arranged on the dam body through a foundation bearing platform, the first lifting arm and the second lifting arm are arranged on the upper part of the standard section through the rotating device, the generator set is arranged on the standard section, the luffing trolley is slidably arranged on the tracks of the first lifting arm and the second lifting arm respectively, and the luffing trolley is connected to the hook through a pulley block and a wire rope.

4. The hydropower station combined mechanical gravity energy storage system according to claim 3 is characterized in that: The rotary lifting equipment also includes an intelligent cab, which is arranged on the upper part of the standard section. An intelligent driving system is arranged in the intelligent cab, and the intelligent driving system includes an automatic positioning module, an automatic take-off and landing module, a remote control module and a fault diagnosis module.

5. The hydropower station combined mechanical gravity energy storage system according to claim 3 is characterized in that: The upper silo and the lower silo are storage-type silos, wherein slide rails are arranged inside the storage-type silos, a skylight which can be opened and closed is arranged on the top of the storage-type silo, and drainage holes are arranged on the lower side wall of the storage-type silo; the gravity block is placed inside the storage-type silo.

6. The hydropower station combined mechanical gravity energy storage system according to claim 5 is characterized in that: The gravity block is a concrete block or a block made of corrosion-resistant environmentally friendly materials, and a positioning chip is arranged inside the gravity block.

7. The hydropower station combined mechanical gravity energy storage system according to any one of claims 1-2 or 4-6, characterized in that: The hydropower station combined with the mechanical gravity energy storage system has an energy storage stage and an energy release stage during operation. During the energy storage stage, the pumped storage power station uses excess electric energy to pump water from the lower reservoir to the upper reservoir, and the mechanical gravity energy storage system uses excess electric energy to drive the rotating lifting equipment, and the rotating lifting equipment transports the gravity block in the lower silo to the upper silo; during the energy release stage, the water storage power station converts the gravitational potential energy of water into electrical energy, and the mechanical gravity energy storage system converts the gravitational potential energy of the gravity block into electrical energy.

8. A method for designing a hydropower station combined mechanical gravity energy storage system, used for designing a hydropower station combined mechanical gravity energy storage system according to any one of claims 1 to 7, characterized in that: The design method comprises the following steps: According to the scale of the pumped storage power station, the mass energy storage density is taken into consideration. The greater the mass energy storage density, the smaller the volume and mass of the mechanical gravity energy storage system required to store the same amount of electrical energy. Combined with the elevation of the main body of the dam, the lifting height of the rotating lifting equipment on the top of the main body of the dam, the location of the loading and unloading yards, and the size and number of gravity blocks are planned; An efficiency model is established to determine the configuration and parameter combination of the mechanical gravity energy storage system.

9. The design method of the hydropower station combined mechanical gravity energy storage system according to claim 8 is characterized in that: When building an efficiency model, include: The mechanical gravity energy storage system converts electrical energy into gravitational potential energy for storage during the energy storage phase, and converts gravitational potential energy into electrical energy by rotating the generator set of the lifting equipment during the energy release phase. The efficiency of the entire system is expressed as: the=the EG ×h ES ; For gravity energy storage, the mass energy storage density is expressed as: U m =mgx; volume energy storage density is: Among them, m is the mass of a single gravity block, x is the displacement of the gravity block, and V is the volume of the gravity block. From the above formula, it can be seen that the energy storage density is related to the displacement during mechanical gravity energy storage. The high altitude of the pumped storage power station has a natural advantage. The energy storage density can be used to measure the mass of the mechanical gravity energy storage device and the size of the space it occupies; The main sources of loss of the mechanical gravity energy storage system in the process of lifting the gravity block and transporting it to the loading or unloading yard are two aspects. On the one hand, the drag coefficient caused by air resistance when the gravity block is lifted / lowered, and on the other hand, the friction loss caused by friction; wherein the drag loss is expressed as: Where A is the windward area of ​​the gravity block, ρ is the air density, and C w is the air resistance coefficient, v(t) represents the rising / falling speed, and t represents the time; The friction loss includes the friction between the variable-length trolley and the track during the translation of the gravity block, the rotational friction of the rotating device, and the friction of the conveying tracks of the loading and unloading yards. The magnitude of the friction force in the friction loss is positively correlated with the mass of the gravity block, so the total friction loss is expressed as: AND f =And f1 +E f2 +E f3 ; Where γ, μ and μ2 represent the coefficients of correlation between friction and the mass of the gravity block, which are relevant to actual engineering projects; v′(t) represents the moving speed of the variable-length trolley; ω(t) is the angular velocity of rotation; r is the rotation radius; and x is the distance that the object is transported by the transport track.

10. The design method of the hydropower station combined mechanical gravity energy storage system according to claim 9, characterized in that: When establishing the efficiency model, the calculation of energy storage efficiency and power generation efficiency is also included; In the energy storage stage, the mechanical gravity energy storage system drives the gravity block to rise, and the gravity block overcomes air resistance to do work. The gravity block needs to overcome friction to do work when it reaches the corresponding position of the loading yard. Considering the motor loss and the bidirectional substation loss, the energy storage efficiency is expressed as: In the formula, E q represents the energy consumed by the gravity block to rise, η G is the efficiency of the electric generator, η inv represents the bidirectional substation efficiency; During the energy release stage, the mechanical gravity energy storage system uses the gravity block's own gravity as a power source, overcomes wind resistance and performs work during the descent process, and the luffing trolley overcomes friction to translate the gravity block from the loading yard to above the unloading yard. During the descent process, the gravity potential energy is converted into kinetic energy, most of which is converted into electrical energy through the generator set and supplied to users through the bidirectional substation and transmission line. The power generation efficiency is: In the formula, E q ′ represents the energy released when the gravity block descends.

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