WO2025180018A1 - Gravity energy storage apparatus based on disused oil, gas and water well group, and power generation system - Google Patents

Abstract

Disclosed are a gravity energy storage apparatus based on a disused oil, gas and water well group, and a power generation system. The gravity energy storage apparatus comprises a secondary control system and a plurality of energy storage working units connected to the secondary control system, and each energy storage working unit comprises a disused oil, gas and water well and a gravity energy storage device. The power generation system comprises a main control system and at least one wind or photovoltaic power generation field for supplying power to a main power grid by means of the gravity energy storage apparatus.

Description

A gravity energy storage device and power generation system based on abandoned oil, gas and water wells

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese patent application No. 202410205992.5 filed in China on February 26, 2024, the entire contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates to the technical fields of wind power generation and kinetic energy storage, and in particular to a gravity energy storage device and a power generation system based on a group of abandoned oil, gas and water wells.

Background Art

Wind and solar energy are both renewable energy sources. Because they originate from nature, they are inexhaustible. This makes wind and photovoltaic power generation a promising option for sustainable electricity supply. Compared to fossil fuel power generation, wind and photovoltaic power generation can significantly reduce carbon dioxide and other greenhouse gas emissions, helping to mitigate the impact of global warming. However, due to both natural and technological factors, wind and photovoltaic power generation is intermittent, random, and has poor dispatchability, which can lead to a series of power quality issues. First, when wind and photovoltaic power generation fluctuate in output power due to weather, this can cause voltage fluctuations on the wind farm's transmission lines, which in turn cause grid voltage fluctuations. Flicker can also occur when the wind power system's output power is high. Second, because wind and photovoltaic power generation have a certain degree of randomness in their unit output, as the proportion of these two renewable energy sources in the total power generation of the grid continues to increase, frequency fluctuations in the grid are likely to occur. These grid frequency issues can negatively impact the power system and its users. Furthermore, because both wind and photovoltaic power generation utilize a large amount of power electronic equipment, they generate significant harmonics and DC components. When harmonics are injected into the power system, they cause voltage distortion in the grid, affecting the power quality of the entire system. When these two renewable energy sources contribute a small portion of their generation, modern power electronics technology can keep these defects within acceptable limits. However, when these two renewable energy sources are integrated into the grid on a large scale, they can significantly impact the power system. The grid must manage the capacity of these two renewable energy sources within a manageable range to minimize any adverse impacts. This not only significantly limits the scale and speed of their deployment, but also leads to the continued dominance of coal-fired power plants, which are known for their significant environmental damage and carbon emissions. To ensure stable grid operation, some of the generation capacity of these two renewable energy sources is often wasted, preventing the renewable energy generation system from achieving the expected economic benefits. To this end, efforts are underway to develop and promote new energy storage technologies and deploy new energy storage power stations to reduce energy waste, improve the efficiency of renewable energy utilization, and ultimately achieve energy conservation and environmental protection. Furthermore, new energy storage technologies can improve energy reliability and stability. Due to the significant capital investment required to build energy storage plants using new energy storage technologies, they currently serve three primary functions: first, balancing electricity supply and demand. Energy storage plants can store energy during peak demand periods to balance power supply and ensure grid stability, helping to reduce the risk of blackouts and improve power system reliability. Second, they integrate renewable energy sources: Renewable energy sources such as wind and solar are volatile, and energy storage plants can capture and store excess power to provide power during volatile periods. Third, they provide frequency regulation and backup power. Energy storage plants can serve as frequency regulators for the power system, rapidly responding to fluctuations in electricity demand. However, this does not completely eliminate the aforementioned adverse effects of these two renewable energy sources on the power grid. To ensure overall grid stability and high power quality, renewable energy sources must account for only a small share of the power supply. Traditional coal-fired power generation, due to its fully controllable generation process and excellent power quality, remains the primary means of power generation. This contradicts the original intention of vigorously developing renewable energy.

Gravity energy storage devices use electric motors to lift heavy objects to a height when there's excess electricity, converting the electrical energy into gravitational potential energy. When the grid needs electricity, the heavy objects generate work, driving a generator to rotate, converting the gravitational potential energy into electricity. Gravity energy storage devices offer advantages such as safety, fast response, large energy storage capacity, and a long lifespan. To ensure long-term external power generation, a common approach involves constructing high-rise energy storage towers or metal structures (typically around 120 meters) on the ground. These stored heavy objects are then lowered sequentially, using the gravity of the objects to drive the generator, generating electricity and converting the gravitational potential energy into electricity. This method requires constant loading and releasing of heavy objects, requiring high precision and introducing a certain degree of uncertainty. After the heavy objects are released to higher or lower levels, they must be strategically arranged and positioned to accommodate more heavy objects and maximize energy storage or release. This places extremely high demands on computer and software operation. Furthermore, the construction of these towers and metal structures is labor-intensive, time-consuming, and costly.

In order to achieve resource reuse, gravity energy storage devices have been constructed using abandoned oil and gas wells, water towers or mines. However, these devices have low energy density and cannot absorb all the electricity generated by local renewable energy, or even store excess electricity from renewable energy. As a result, such gravity energy storage devices are not widely used.

Summary of the Invention

The present disclosure aims to solve one of the technical problems in the related art at least to a certain extent.

To this end, the disclosed embodiment provides a gravity energy storage device and a power generation system based on a group of abandoned oil, gas and water wells, and a power generation system having the gravity energy storage device. The disclosed embodiment adopts a well group composed of a plurality of abandoned oil, gas and water wells, and constructs a gravity energy storage device by adding energy storage equipment, so as to achieve large-capacity and multiple modes of energy storage and release. The disclosed embodiment connects the above-mentioned gravity energy storage device between the existing wind power or photovoltaic power generation system and the power grid, so that the electric energy generated by the above-mentioned two new energy sources is not directly input into the main power grid, but is stored by the above-mentioned gravity energy storage device; when the main power grid needs electric energy, the above-mentioned gravity energy storage device releases energy, and the energy release process of the above-mentioned gravity energy storage device is fully controllable, which completely eliminates the technical problems caused by the instability of power generation of the two new energy sources. At the same time, a power supply pattern based on new energy is established for some areas, and the possibility of gradually withdrawing coal-fired power plants from the power system is explored.

In order to achieve the above objectives, the present disclosure adopts the following technical solutions:

A gravity energy storage device based on an abandoned oil, gas and water well group provided in an embodiment of the first aspect of the present disclosure includes a sub-control system and a plurality of energy storage working units, each energy storage working unit is connected to the sub-control system via a control cable;

The energy storage working unit includes an abandoned oil, gas and water well and a gravity energy storage device, wherein the gravity energy storage device includes a weight, a suspension mechanism, a first transmission and a generator motor connected in sequence, wherein the generator motor is connected to the power cable of the wind or photovoltaic power generation system through a power cable, and the height of the weight in the abandoned oil, gas and water well is changed by the suspension mechanism to achieve energy storage and release;

The sub-control system is used to open or close a corresponding number of the energy storage working units according to the energy storage or release capacity requirements of the overall control system of the wind or photovoltaic power generation system, control and monitor the equipment status in each energy storage working unit, transmit the status and parameters of the gravity energy storage device to the overall control system, and re-regulate the gravity energy storage device according to the instructions issued by the overall control system.

In some embodiments, the abandoned oil, gas and water wells are wells that have been abandoned after the exploitation of underground gases and liquids including oil, natural gas and groundwater, and are more than 200 meters deep.

In some embodiments, the weight is made of a material with a mass of more than 5,000 kg and an average density of more than 3,000 kg/m3, and a safety distance should be reserved between the lowest and highest positions of the weight in the well and the bottom and wellhead respectively.

In some embodiments, the suspension mechanism includes a wire rope, a fixed pulley, a drum and a drum brake, one end of the wire rope is fixedly connected to the top of the weight, and the other end is passed around the fixed pulley located above the wellhead and wound around the drum located on one side of the wellhead, the drum is sleeved on the drum shaft, one end of the drum shaft is connected to the low-speed shaft of the first transmission, the high-speed shaft of the first transmission is connected to the generator motor, a switch is provided on the power cable, and the drum brake, switch and generator motor are connected to the sub-control system through the control cable.

In some embodiments, a load stabilizer is provided at the other end of the drum shaft, and the load stabilizer eliminates the influence of the gravity change of the wire rope in the well on the torque of the drum and the generator motor by absorbing and releasing elastic potential energy.

In some embodiments, the load stabilizer includes an elastic element and a second transmission. The other end of the reel shaft is connected to the high-speed shaft of the second transmission, and is transmitted to the elastic element after being decelerated by the second transmission. The elastic element gradually changes the torque on the reel and the generator motor in a linear manner, so that the torque acting on the reel and the generator motor remains constant.

In some embodiments, the elastic element is a coil spring with linear characteristics, and the second transmission is a planetary transmission.

In some embodiments, the sub-control system includes a first operation controller and a depth sensor, a first grid-connected control unit, a first safety protection unit, a first monitoring unit, a first communication interface circuit and a first user interface connected thereto; the depth sensor is used to detect the depth of the heavy object in the well; the first grid-connected control unit is used to connect the electric energy generated by the gravity energy storage device to the main power grid; the first safety protection unit is used to deal with emergencies, and when the parameters exceed the preset working range, the problematic energy storage working unit or even the entire gravity energy storage device is shut down in time; the first monitoring unit is used to monitor the working status of the energy storage working unit in real time and transmit the data to the first operation control unit, the first safety protection unit and the first user interface; the first communication interface circuit is used to realize data communication; the first user interface is used to input user instructions, change parameters, and display the operating status, data and fault conditions of the gravity energy storage device; the first operation controller is used for operation monitoring of the gravity energy storage device, including start and stop control, control of various electronic components and grid monitoring.

In some embodiments, the sub-control system controls the working mode of each energy storage working unit according to the energy storage and release instructions of the overall control system of the wind or photovoltaic power generation system: when the wind farm or photovoltaic power generation site generates less power, the overall control system instructs the sub-control system of the gravity energy storage device to start a single or multiple energy storage working units to participate in energy storage; when the power generation of the wind farm or photovoltaic power generation site is close to full load, the overall control system instructs the sub-control system to start all energy storage working units to participate in energy storage at the same time; when the power generation of the wind farm or photovoltaic power generation site gradually increases, the overall control system instructs the sub-control system to start a single or multiple energy storage working units to participate in energy storage in succession.

In some embodiments, the operation process of the gravity energy storage device includes:

During energy storage operation: the sub-control system opens the gravity energy storage equipment of the corresponding number of energy storage working units according to the energy storage capacity requirements of the overall control system. In the gravity energy storage equipment of the opened energy storage working units, the sub-control system first starts the suspension mechanism, and then connects the power cable to start the generator motor, and uses the suspension mechanism to lift the heavy object that is at the lower predetermined depth of the well or has not yet reached the upper predetermined depth of the well; when the heavy object reaches the upper predetermined depth of the adjacent well, the sub-control system first disconnects the power cable, brakes the generator motor to reduce its rotation speed, and then controls the suspension mechanism to reduce the lifting speed of the heavy object; when the heavy object reaches the upper predetermined depth of the well, the sub-control system controls the suspension mechanism to keep the height of the heavy object unchanged, thereby realizing the conversion of excess electrical energy into heavy objects. gravitational potential energy and stores it; if there is still surplus electrical energy to be stored, the sub-control system will continue to open the gravity energy storage equipment of the remaining energy storage working units until the entire gravity energy storage device lifts the weights in all energy storage working units to the upper predetermined depth of the well, achieving full-load energy storage and the energy storage operation is completed; when a single or part of the energy storage workstations are in the energy storage process and there is an unexpected lack of energy storage capacity, the sub-control system will disconnect the power cable, brake the generator motor to reduce its speed, and then control the suspension mechanism to make the weight in the well hover at the current position, and the energy storage operation will be suspended. If there is subsequent energy storage requirement, the energy storage working unit whose energy storage operation has been suspended will continue the energy storage operation until the weight reaches the upper predetermined depth of the well, achieving full-load energy storage of the energy storage working unit, and finally achieving full-load energy storage of the gravity energy storage device;

During the energy release operation: the sub-control system opens the gravity energy storage devices of the corresponding number of energy storage working units according to the required energy release capacity. In the gravity energy storage devices of the opened energy storage working units, the sub-control system first connects the power cable to start the generator motor, and then controls the suspension mechanism to continuously lower the weight in the well by releasing the wire rope; when the weight reaches the lower predetermined depth of the well, the sub-control system disconnects the power cable, brakes the generator motor to reduce its rotation speed, and then controls the suspension mechanism to reduce the descent speed of the weight; when the weight reaches the lower predetermined depth of the well, the sub-control system controls the suspension mechanism to keep the height of the weight unchanged, thereby realizing the conversion of the gravitational potential energy of the weight into electrical energy; if the gravity storage If the energy storage device still has energy release requirements, the control system will open the gravity energy storage equipment of the remaining corresponding number of energy storage working units until the entire gravity energy storage device lowers the weights in all energy storage working units to the lower predetermined depth of the well to achieve full-load energy release; when a single or part of the energy storage working units are in the process of releasing energy and an unexpected situation occurs where energy release is not required, the sub-control system will first disconnect the power cable and brake the generator motor to reduce its speed, and then control the suspension structure to make the weight in the well hover at the current position, and the energy release operation will be suspended. If there is a subsequent energy release requirement, the energy storage working unit whose energy release operation has been suspended will continue the energy release operation until the weight reaches the lower predetermined depth of the well, thereby achieving full-load energy release of the energy storage working unit and finally achieving full-load energy release of the gravity energy storage device.

A second aspect of the present disclosure provides a power generation system, which is a wind or photovoltaic power generation system, comprising a master control system and at least one wind or photovoltaic power plant that supplies power to a main power grid through a gravity energy storage device, wherein the gravity energy storage device adopts the gravity energy storage device according to any embodiment of the first aspect of the present disclosure, and a boost control device is further connected between the gravity energy storage device and the main power grid; each wind or photovoltaic power plant is configured with at least three gravity energy storage devices, and the maximum rated power generation power of the wind or photovoltaic power plant is equal to the energy storage power of one gravity energy storage device. When the wind or photovoltaic power plant generates electricity, one gravity energy storage device performs energy storage operation, one gravity energy storage device performs energy release operation, and at least one gravity energy storage device is in a full-load energy storage state; the sub-control systems in the wind or photovoltaic power plant and each gravity energy storage device are connected to the master control system through control cables, and power is transmitted between the wind or photovoltaic power plant, the gravity energy storage device and the main power grid through power cables;

The overall control system is used to open and close the corresponding gravity energy storage device to store energy and output electrical energy to the main power grid according to the power generation and operating conditions of the wind or photovoltaic power plant, and to monitor the operating conditions of the power generation system.

In some embodiments, the overall control system includes a second operation controller and a second grid-connected control unit, a second safety protection unit, a second monitoring unit, a second communication interface circuit and a second user interface connected thereto; the second grid-connected control unit is used to connect the electric energy generated by the gravity energy storage device to the main power grid; the second safety protection unit is used to deal with emergencies, and when the parameters exceed the preset working range, the problematic energy storage working unit or even the entire gravity energy storage device is shut down in time; the second monitoring unit is used to monitor the working status of the energy storage working unit in real time and transmit the data to the second operation control unit, the second safety protection unit and the second user interface; the second communication interface circuit is used to realize data communication; the second user interface is used to input user instructions, change parameters, and display the operating status, data and fault conditions of the gravity energy storage device; the second operation controller is used for operation monitoring of the power generation system, including start and stop control, control of various electronic devices and grid monitoring.

In some embodiments, the operation process of the power generation system includes:

During energy storage operation: the control system of the wind power or photovoltaic power plant sends the value of the wind power or photovoltaic power generation power that can be achieved and the power generation power scale in the future to the general control system in real time, and the general control system sends an energy storage operation instruction to a gravity energy storage device that is not in full load energy storage, and the sub-control system of the gravity energy storage device starts the corresponding number of energy storage working units in the gravity energy storage device. At the same time, the general control system sends an instruction to the control system of the wind power or photovoltaic power plant, connects the power cable between the wind power or photovoltaic power plant and the gravity energy storage device, and the gravity energy storage device that receives the energy storage operation instruction starts energy storage. During the energy storage operation, the general control system obtains various data of the gravity energy storage device and the wind power or photovoltaic power plant in real time and sends control instructions. When the gravity energy storage device that performs the energy storage operation When the energy storage device reaches full load energy storage, the main control system sends an instruction to the sub-control system to end the current energy storage operation of the gravity energy storage device, and sends an energy storage operation instruction again to a gravity energy storage device that has completed energy release. The gravity energy storage device that receives the energy storage operation instruction starts the corresponding number of energy storage working units in the gravity energy storage device through the sub-control system; when the power generation value of the wind power or photovoltaic power plant cannot meet the starting power of any energy storage working unit in the gravity energy storage device, the main control system sends an instruction to the control system of the wind power or photovoltaic power plant to cut off the power cable between the wind power or photovoltaic power plant and the gravity energy storage device, and at the same time, the main control system sends an instruction to the sub-control system of the gravity energy storage device that is performing energy storage operation to shut down the energy storage working unit that is performing energy storage operation;

During energy release operation: the general control system preferentially sends the energy release demand instruction of the main power grid to a gravity energy storage device that has fully stored energy. The gravity energy storage device starts the energy release operation, and its sub-control system activates the corresponding energy storage working unit to start the energy release operation. During the energy release operation, the general control system obtains various data of the gravity energy storage device and the wind or photovoltaic power plant in real time and issues control instructions. When the gravity energy storage device finishes releasing energy, the general control system sends the current energy release demand instruction of the main power grid to another gravity energy storage device that has fully stored energy. The power generation system continues to generate electricity until all gravity energy storage devices in the power generation system can no longer meet the power supply demand of the main power grid. The general control system controls the boost control device to disconnect the power cable between the gravity energy storage device and the main power grid.

The embodiments of the present disclosure have the following features and beneficial effects:

The disclosed embodiment adopts a well group consisting of multiple abandoned oil, gas and water wells, and constructs a gravity energy storage device by adding energy storage equipment. Multiple gravity energy storage devices correspond to one wind or photovoltaic power plant, which can achieve large-capacity and multi-mode energy storage and release. Specifically, the energy storage capacity of each gravity energy storage device can store the electric energy generated by the corresponding wind farm or photovoltaic power plant at full load within a certain period of time. During the period when the output of the wind farm or photovoltaic power plant decreases or there is no output at all due to natural reasons, multiple gravity energy storage devices will continue to generate electricity. In each gravity energy storage device, a single well or multiple wells can participate in energy storage or release at the same time, all wells can participate in energy storage or release at the same time, a single well can participate in energy storage or release successively, and some well groups can participate in energy storage or release as a whole. This not only ensures that the wind farm can generate electricity steadily under the conditions of light breeze and constantly changing wind speed, or the photovoltaic power farm can generate electricity steadily under the conditions of low-intensity light or constantly changing light intensity, but also meets the main power grid's requirements for the gravity energy storage device to release electricity in a constantly changing manner. More importantly, wind farms or photovoltaic power plants do not directly supply electricity to the main power grid. Instead, they generate electricity and are connected to the grid through gravity energy storage devices. The electricity generated by the gravity energy storage devices remains constant, thereby eliminating the adverse effects of wind or solar power generation on the main power grid and creating conditions for increasing the proportion of the above two types of renewable energy power generation in the regional power grid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the layout of a gravity energy storage device based on an abandoned oil, gas and water well group provided by an embodiment of the first aspect of the present disclosure;

FIG2 is a side view of a single energy storage working unit in the gravity energy storage device shown in FIG1 ;

FIG3 is a top view of a single energy storage working unit in the gravity energy storage device shown in FIG1 ;

FIG4 is a schematic diagram of a weight in a single energy storage working unit of the gravity energy storage device shown in FIG1 reaching an upper predetermined depth and a lower predetermined depth in a well;

FIG5 is a schematic structural diagram of a sub-control system or a total control system in the gravity energy storage device shown in FIG1 ;

FIG6 is a schematic side view of the internal structure of the load stabilizer in the gravity energy storage unit shown in FIG2;

FIG7 is a schematic top view of the internal structure of the load stabilizer in the gravity energy storage unit shown in FIG2 ;

FIG8 is a schematic structural diagram of a power generation system having the gravity energy storage device according to an embodiment of the second aspect of the present disclosure.

Reference numerals:
100-Energy storage working unit, 110-Abandoned oil, gas and water wells, 120-Gravity energy storage equipment, 121-Heavy objects, 122-Suspension mechanism, 1221-
Steel wire rope, 1222-fixed pulley, 1223-drum, 1224-drum brake, 123-generator motor, 124-first transmission, 125-load stabilizer, 1251-elastic element, 1252-second transmission, 126-power cable, 127-switch;
200-control cable;
300-sub-control system, 310-depth sensor, 320-operation controller, 330-grid connection control unit, 340-safety protection unit, 350-monitoring unit, 360-communication interface circuit, 370-user interface;
400-Power generation system, 410-Wind farm, 411-Wind turbine generator set, 412-Wind farm power collection system, 413-Wind farm control system, 420-Gravity energy storage device, 430-Master control system, 440-Power cable, 450-Boost control device;
500-Main grid.

DETAILED DESCRIPTION

In order to make the purpose, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure and are not intended to limit the present disclosure.

Rather, the present disclosure encompasses any alternatives, modifications, equivalents, and solutions that are within the spirit and scope of the present disclosure as defined by the claims. Furthermore, to facilitate a better understanding of the present disclosure, certain specific details are described in detail below in the detailed description of the present disclosure. A person skilled in the art will be able to fully understand the present disclosure without these details.

In the description of the present disclosure, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the basis or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present disclosure. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present disclosure, "multiple" means two or more, unless otherwise clearly and specifically defined.

In the description of this disclosure, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this disclosure based on specific circumstances.

In the present disclosure, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

1 to 4 , a gravity energy storage device based on an abandoned oil, gas and water well group is provided in accordance with an embodiment of the first aspect of the present disclosure, comprising: a plurality of energy storage working units 100 and a sub-control system 300 , wherein each energy storage working unit 100 is connected to the sub-control system 300 via a control cable 200 ;

The energy storage working unit 100 includes an abandoned oil, gas, and water well 110 and a gravity energy storage device 120. The gravity energy storage device 120 includes a weight 121, a suspension mechanism 122, a first transmission 124, and a generator motor 123 connected in sequence. The generator motor 123 is connected to the power cable of the wind or photovoltaic power generation system through a power cable 126. The suspension mechanism 122 is used to change the height of the weight 121 in the abandoned oil, gas, and water well 110 to achieve energy storage and release.

The sub-control system 300 is used to open or close a corresponding number of the energy storage working units according to the energy storage or release capacity requirements of the overall control system of the wind power or photovoltaic power generation system, control and monitor the equipment status in each energy storage working unit, transmit the status and parameters of the gravity energy storage device to the overall control system, and further regulate the gravity energy storage device according to the instructions issued by the overall control system.

In some embodiments, the sub-control system 300 controls the working mode of each energy storage working unit 100 according to the energy storage and release instructions of the overall control system of the wind power or photovoltaic power generation system: when the wind power plant or photovoltaic power generation site generates less power, the overall control system of the power generation system instructs the sub-control system 300 of the gravity energy storage device to start a single or multiple energy storage working units 100 to participate in energy storage; when the power generation of the wind power plant or photovoltaic power generation site is close to full load, the overall control system 430 instructs the sub-control system 300 to start all energy storage working units 100 to participate in energy storage at the same time; when the power generation of the wind power plant or photovoltaic power generation site gradually increases, the overall control system instructs the sub-control system 300 to start a single or multiple energy storage working units 100 to participate in energy storage in succession.

In some embodiments, the number of energy storage working units 100 can be 2 or more, or even hundreds, to achieve the reuse of abandoned well groups and greatly save construction costs.

In some embodiments, each energy storage unit 100 has the same structure and includes an abandoned oil, gas, and water well 110 and a gravity energy storage device 120. The abandoned oil, gas, and water well 110 refers to a well with a depth of more than 200 meters that has been abandoned after the extraction of underground gases and liquids such as oil, natural gas, and groundwater. The gravity energy storage device 120 includes a weight 121, a suspension mechanism 122, and a generator motor 123 connected in sequence. The weight 121 is suspended in the abandoned oil, gas, and water well 110 by the suspension mechanism 122. The weight 121 can be made of a material with a mass of more than 5,000 kilograms and an average density of more than 3,000 kilograms per cubic meter. A safe distance should be reserved between the lowest and highest positions of the weight 121 in the well and the bottom and wellhead, respectively, to prevent the weight 121 from damaging the bottom of the well when it descends to the lowest position and to prevent the weight 121 from damaging the facilities outside the well when it is lifted to the highest position. The suspension mechanism 122 includes a wire rope 1221, a fixed pulley 1222, a drum 1223, and a drum brake 1224. One end of the wire rope 1221 is fixedly connected to the top of the weight 121, and the other end passes over the fixed pulley 1222 located above the wellhead and is wound around the drum 1223 located on one side of the wellhead. The support shaft of the fixed pulley 1222 is connected to the foundation, and the drum 1223 is mounted on the drum shaft. One end of the drum shaft is connected to the low-speed shaft of the first transmission 124, and the high-speed shaft of the first transmission 124 is connected to the generator motor 123. The generator motor 123 is connected to the power cables of the power generation system via a power cable 126 equipped with a switch 127. The sub-control system 300 controls the opening and closing of the switch 127 on the power cable 126, and controls the current and voltage of the excitation winding in the generator motor 123 and the activation and deactivation of the electromagnetic brake. The first transmission 124 can be a planetary transmission or other type of transmission.

In some embodiments, as shown in Figures 4 and 5, the sub-control system 300 includes a depth sensor 310, an operation controller 320, a grid connection control unit 330, a safety protection unit 340, a monitoring unit 350, a communication interface circuit 360, and a user interface 370. The depth sensor 310 is positioned near the abandoned oil, gas, and water well 110, such as at the wellhead of the abandoned oil, gas, and water well 110, to detect the depth of the weight 121 within the well. A laser rangefinder can be used to measure the depth of the weight 121 using the principle of laser ranging. The grid connection control unit 330 is used to connect the power generated by the gravity energy storage device to the main power grid 500. The safety protection unit 340 is used to handle emergencies. When parameters exceed the preset operating range, it promptly shuts down the problematic energy storage unit 100, or even the entire gravity energy storage device. The monitoring unit 350 is used to monitor the operating status of the gravity energy storage device 120 and the energy storage unit 100 in real time and transmit the data to the operation control unit 320, the safety protection unit 340, and the user interface 370. The communication interface circuit 360 is used for data communication between the sub-control system 300 and the overall control system 430. The user interface 370 is used to input user commands, change parameters, and display the operating status, data, and fault conditions of the gravity energy storage device. The human-computer interaction and display functions of the user interface 370 are implemented through the computer user display system and real-time tracing system. The operation controller 320, as the core of the sub-control system 300, is connected to the depth sensor 310, the grid-connected control unit 330, the safety protection unit 340, the monitoring unit 350, the communication interface circuit 360, and the user interface 370. It performs operation monitoring, including system startup and shutdown, control of other functional modules, and grid monitoring. The operation control system 320 mainly implements these functions through a programmable controller. In addition, the operation control system 320 of the sub-control system 300 is connected to the sensors that need to be controlled in the energy storage working unit 100, such as the depth sensor 310 for detecting the depth of heavy objects, through the control cable 200, and is also connected to the drum brake 1224, the generator motor 123 and the switch 127 to realize the control of the working mode of the energy storage working unit 100 and the monitoring of the working status.

In some embodiments, considering that when the weight 121 descends and the wire rope 1221 in the well gradually becomes longer, the gravity of the wire rope 1221 gradually increases, and the torque on the drum 1223 gradually increases, and the torque effect on the generator motor 123 also increases continuously, therefore, a load stabilizer 125 is provided at the other end of the reel coaxially. The load stabilizer 125 eliminates the influence of the gravity change of the wire rope 1221 in the well on the torque of the generator motor 123 by absorbing and releasing elastic potential energy. Specifically, referring to Figures 6 and 7, the load stabilizer 125 includes an elastic element 1251 and a second transmission 1252. The other end of the shaft of the reel 1223 is connected to the high-speed shaft of the second transmission 1252. The second transmission 1252 decelerates the shaft and transmits the torque to the elastic element 1251. The elastic element 1251 gradually reduces the torque on the reel 1223 in a linear manner, thereby keeping the torque acting on the reel 1223 constant and also keeping the torque acting on the generator motor 123 constant. Similarly, when the weight 121 rises, As wire rope 1221 within the well gradually shortens, the weight of wire rope 1221 gradually decreases, resulting in a decreasing torque on drum 1223. The other end of the drum 1223 shaft is connected to the high-speed shaft of second transmission 1252. After being decelerated by second transmission 1252, the torque is transmitted to elastic element 1251. Elastic element 1251 gradually increases the torque on drum 1223 in a linear manner, thereby maintaining a constant torque on drum 1223 and, consequently, the torque on generator motor 123. In some embodiments, elastic element 1251 is a coil spring with linear characteristics, one end of which is fixed to the housing and the other end to the rotating shaft. The force acting on the rotating shaft is F = kx, where k is the spring's elastic coefficient and x is the spring's deformation. The second transmission 1252 adopts a planetary transmission. The advantage is that the input shaft and the output shaft remain on the same axis, which is highly efficient. In addition: when the outer gear ring of the planetary transmission is fixed, the first-stage speed increase ratio of the planetary wheel carrier shaft and the sun wheel shaft can reach 1:7. The coil spring can generally be rotated 30 times from the shaft rotation to the tightening direction, so that the drum can reach 210 rotations through the speed increase ratio. When the diameter of the drum 1223 is 3.5 meters, the maximum unfolding length of the wire rope 1221 can reach 2300 meters. In addition, the vertical height of the weight 121 is above 100 meters. For most abandoned oil, gas and water wells with a vertical depth of less than 2200 meters, the number of rotations of the drum 1223 when the wire rope 1221 is unfolded is fully met.

In some embodiments, the operation process of the gravity energy storage device provided in the first aspect of the present disclosure includes:

During energy storage operation, the sub-control system 300 controls the activation of the corresponding number of gravity energy storage devices 120 of the energy storage working units 100 based on the required energy storage capacity. In the gravity energy storage devices 120 of the activated energy storage working units 100, the operation controller 320 in the sub-control system 300 first controls the drum brake 1224 to release the drum 1223 through the communication interface circuit 360, then controls the switch 127 on the power cable 126 to turn on, and simultaneously activates the generator motor 123. The generator motor 123 reduces its speed through the first transmission 124 to drive the drum 1223 to rotate. The drum 1223 changes direction via the steel wire rope 1221 wound thereon and the fixed pulley 1222, thereby lifting the heavy object 121 at the lower predetermined depth of the abandoned oil, gas, and water well 110, or the heavy object 121 that has not yet reached the upper predetermined depth of the well. When the weight 121 is close to reaching the upper predetermined depth of the abandoned oil, gas and water well 110, the operation controller 320 in the sub-control system 300 first disconnects the switch 127 on the power cable 126 through the communication interface circuit 360, and brakes the generator motor 123 to reduce its rotation speed, and then controls the drum brake 1224 to brake the drum 1223 to reduce its rotation speed, and finally controls the drum brake 1224 to lock the drum 1223, thereby converting electrical energy into the gravitational potential energy of the weight 121. During the energy storage process of the energy storage working unit 100, the torque generated by the gravity of the wire rope 1221 and the torque generated by the elastic potential energy released by the load stabilizer 125 offset each other, thereby completing energy storage under the stable load state of the generator motor 123. Specifically: due to the abandoned oil, gas and water well 110 0 is deeper, and the influence of the gravity of the wire rope 1221 must be considered. After the drum 1223 winds up a part of the wire rope 1221, the gravity of the wire rope 1221 in the well gradually decreases according to a linear law, and the torque of the wire rope 1221 on the drum 1223 also gradually decreases according to a linear law. The load of the generator motor 123 gradually decreases. In order to stabilize the load, the load stabilizer 125 gradually increases the corresponding load at the same time. The load stabilizer 125 adopts the principle of winding a spring, so the load stabilizer 125 gradually increases the torque on the drum 1223 according to a linear law, so that the torque acting on the drum 1223 remains constant, thereby making the load of the generator motor 123 stable, and the load stabilizer 125 stores the gravity release energy of this section of wire 1221 out of the well in the form of elastic potential energy. If there is still surplus electrical energy to be stored, the sub-control system 300 activates the gravity energy storage devices 120 of the remaining energy storage working units 100 until the entire gravity energy storage device lifts the weights 121 in all energy storage working units 100 to the upper predetermined depth of the abandoned oil, gas and water well 110, achieving full-load energy storage. When a single or part of the energy storage working units 100 are in the process of storing energy and unexpectedly run out of energy storage capacity, the sub-control system 300 disconnects the power cable 126 and brakes the generator motor 123 to reduce its speed, then controls the drum brake 1224 to brake the drum 1223 to reduce its speed, and then controls the drum brake 1224 to lock the drum 1223, so that the weight 121 in the well is suspended at the current position, and the energy storage operation is suspended. If there is a subsequent energy storage requirement, the energy storage working unit 100 whose energy storage operation has been suspended can continue the energy storage operation until the weight 121 reaches the predetermined depth at the top of the well, thereby achieving full-load energy storage of the energy storage working unit 100 and further achieving full-load energy storage of the gravity energy storage device.

During energy release, the sub-control system 300 activates the corresponding number of gravity energy storage devices 120 of the energy storage work units 100 based on the required energy release capacity. In the activated gravity energy storage devices 120 of the energy storage workstations 100, the operation controller 320 in the sub-control system 300, through the communication interface circuit 360, first controls the switch 127 on the power cable 126 to turn on the generator motor 123, and then controls the drum brake 1224 to release the drum 1223. The weight 121 pulls on the wire rope 1221, which changes direction via the fixed pulley 1222, pulling the drum 1223 on the ground to rotate. The drum 1223 then increases its speed via the first transmission 124, driving the generator motor 123 to generate electricity. As the drum 1223 rotates, the weight 121 is continuously lowered by releasing the wire rope 1221. When the weight 121 is at a predetermined depth below the abandoned oil, gas or water well 110, the sub-control system 300 controls the switch 127 to disconnect the power cable 126, then brakes the generator motor 123 to reduce its rotation speed, and then brakes the drum brake 1224 to reduce its rotation speed. When the weight 121 drops to the predetermined depth below the well, the operation controller 320 in the sub-control system 300 first controls the drum brake 1224 to lock the drum 1223 through the communication interface circuit 360, thereby converting the gravitational potential energy of the weight 121 into electrical energy. During the entire energy release process of the energy storage working unit 100, the gravitational energy released by the wire rope 1221 is converted into the elastic potential energy of the load stabilizer 125, thereby making the energy storage working unit 100 0 can generate electricity stably. Specifically, since the abandoned oil, gas and water well 110 is deep, the influence of the gravity of the wire rope 1221 must be considered. When the wire rope 1221 wound on the drum 1223 is lowered into the well along with the weight 121, as the gravity of the wire rope 1221 gradually increases, the gravity of the wire rope 121 lowered into the well gradually increases the torque on the drum 1223 in a linear manner, which may cause the unstable power generation. The load stabilizer 125 gradually releases the stored elastic potential energy, causing the load stabilizer 125 to gradually reduce the torque on the drum 1223 in a linear manner, thereby keeping the torque acting on the drum 1223 constant, thereby making the load of the generator motor 123 stable. If the gravity energy storage device still requires energy release, the sub-control system 300 activates the gravity energy storage devices 120 of the corresponding number of remaining energy storage working units 100 in the gravity energy storage device until the entire gravity energy storage device lowers the weights 121 in all energy storage working units 100 to the predetermined depth below the abandoned oil, gas and water well 110, achieving full-load energy release. If a single or partial energy storage working unit 100 is in the process of releasing energy and the power grid unexpectedly does not need to release energy, the safety protection unit of the sub-control system 300 will disconnect the power cable 126 and brake the generator motor 123 to reduce its speed. The sub-control system 300 then controls the drum brake 1224 to brake the drum 1223 to reduce its speed. Finally, the sub-control system 300 controls the drum brake 1224 to lock the drum 1223, causing the weight 121 in the well to hover at the current position, and the energy release operation is suspended. If there is a subsequent energy release requirement, the energy storage working unit 100 whose energy release operation has been suspended can continue to release energy until the weight 121 reaches the predetermined depth at the bottom of the well. The energy release operation of the energy storage working unit 100 is completed, and the full load energy release of the gravity energy storage device is finally achieved.

In some embodiments, when the gravity energy storage device stores energy according to energy storage capacity requirements:

When the required energy storage capacity approaches or equals the energy storage capacity of the entire gravity energy storage device, the sub-control system 300 activates the gravity energy storage devices 120 of all energy storage working units 100 in the gravity energy storage device. In all activated gravity energy storage devices 120 of the energy storage working units 100, the operation controller 320 in the sub-control system 300 first controls the drum brake 1224 to release the drum 1223 through the communication interface circuit 360, then controls the switch 127 to connect the power cable 126, and simultaneously activates the generator motor 123. The generator motor 123 rotates the drum 1223 at a reduced speed through the first transmission 124. The drum 1223 changes direction via the wire rope 1221 wound around it and the fixed pulley 1222, thereby lifting the weight 121 at a predetermined depth below the abandoned oil, gas, and water well 110. When the weight 121 reaches the upper predetermined depth near the abandoned oil, gas and water well 110, the operation controller 320 in the sub-control system 300 first controls the switch 127 to disconnect the power cable 126 through the communication interface circuit 360, and brakes the generator motor 123 to reduce its rotation speed, and then controls the drum brake 1224 to brake the drum 1223 to reduce its rotation speed. When the weight 121 finally reaches the upper predetermined depth of the abandoned oil, gas and water well 110, the sub-control system 300 controls the drum brake 1224 to lock the drum 1223, ending the energy storage operation of the gravity energy storage device. During the energy storage process, the torque generated by the elastic potential of the load stabilizer 125 offsets the torque generated by the gravity of the wire rope 1221, so that the energy storage working unit 100 can absorb electrical energy smoothly.

In some embodiments, when the gravity energy storage device releases energy according to the energy release capacity:

When the required energy release capacity approaches or equals the energy storage capacity of the entire gravity energy storage device, sub-control system 300 activates all energy storage working units 100. In the gravity energy storage devices 120 of all activated energy storage working units 100, operation controller 320 within sub-control system 300, via communication interface circuit 360, first controls switch 127 to connect power cable 126 and then controls drum brake 1224 to release drum 1223. A weight 121 at a predetermined depth above abandoned oil, gas, or water well 110 pulls down one end of wire rope 1221. The other end of wire rope 1221 changes direction via fixed pulley 1222, pulling drum 1223 to rotate. Drum 1223 rotates the low-speed shaft of first transmission 124, which in turn drives motor generator 123 to generate electricity, achieving energy release. When the weight 121 reaches the predetermined depth below the abandoned oil, gas and water well 110, the operation controller 320 in the sub-control system 300 first controls the switch 127 to disconnect the power cable 126 through the communication interface circuit 360, and brakes the generator motor 123 to reduce its rotation speed, and then controls the drum brake 1224 to brake the drum 1223 to reduce its rotation speed. When the weight 121 finally reaches the predetermined depth below the abandoned oil, gas and water well 110, the sub-control system 300 controls the drum brake 1224 to lock the drum 1223, and the gravity energy storage device ends the energy release operation. During the entire energy release process, the gravitational potential energy of the wire rope 1221 is converted into the elastic potential energy of the load stabilizer 125, so that the energy storage working unit 100 can generate electrical energy smoothly.

Referring to FIG8 , a power generation system 400 provided in an embodiment of the second aspect of the present disclosure includes a general control system 430 and at least one wind farm 410 that supplies power to a main grid 500 through a gravity energy storage device 420. The gravity energy storage device 420 adopts the gravity energy storage device provided in any embodiment of the first aspect of the present disclosure, and a boost control device 450 is further connected between the gravity energy storage device 420 and the main grid 500. Each wind farm 410 is configured with at least three gravity energy storage devices 420, and the maximum rated power generation power of the wind farm 410 is equal to the energy storage power of one gravity energy storage device 420. When the wind farm 410 generates electricity, there is only one gravity energy storage device 420 in an energy storage state, that is, it is performing an energy storage operation (to avoid wind speed due to excessive load). The power plant tripping problem), one gravity energy storage device 420 is in the energy release state, that is, it is supplying power to the main grid 500, and at least one gravity energy storage device 420 is in the state of full-load energy storage, ready to supply power to the main grid 500; the sub-control systems 300 in the wind farm 410 and each gravity energy storage device 420 are connected to the main control system 430 through the control cable 200, and power is transmitted between the wind farm 410, the gravity energy storage device 420 and the main grid 500 through the power cable 440; the main control system 430 is used to open and close the corresponding gravity energy storage device 420 for energy storage and output power to the main grid 500 according to the power generation and operation status of the wind farm 410, and monitor the operation status of the power generation system 400.

In some embodiments, a wind farm 410 includes several wind turbines 411, a wind farm power collection system 412, and a wind farm control system 413. Each wind turbine 411 is connected to the wind farm power collection system 412 via a power cable 440. The wind farm power collection system 412 is connected to the power cables 126 within each energy storage working unit 100 in the gravity energy storage device 420 via the power cables 440. Each power cable 126 is first connected to the boost control device 450 via the power cables 440 and then to the main power grid 500 via the power cables 440. The wind farm power collection system 412 is connected to the wind farm control system 413 via the control cables 200. The wind farm control system 413 is connected to the main control system 430 via the control cables 200.

In some embodiments, the overall control system 430 is substantially identical in structure to the sub-control system 300 in the gravity energy storage device 420 , with the difference being that the overall control system 430 is not provided with a depth sensor, which will not be further described here.

The operation process of the power generation system provided by the second embodiment of the present disclosure is now described as follows:

During energy storage operation: the wind farm control system 413 sends the value of the wind farm power generation capacity and the power generation scale in the future (such as the next 4 hours) to the general control system 430 in real time. The general control system 430 sends an energy storage operation instruction to a gravity energy storage device 420 that is not in full load energy storage through its internal operation controller. The operation controller of the sub-control system 300 of the gravity energy storage device 420 starts the corresponding number of energy storage working units 100 in the gravity energy storage device 420. At the same time, the general control system 430 sends instructions to the wind farm control system 413 to control the wind farm power generation capacity. The field power collection system 412 is connected to the power cable 440, and the gravity energy storage device 420, which receives the energy storage operation instruction, starts to store energy. During the energy storage operation, the operation controller of the overall control system 430 obtains various data of the gravity energy storage device 420 and the wind farm 410 in real time through the communication interface circuit 360 and issues control instructions. The real-time status of the gravity energy storage device 420 and the wind farm 410 is obtained through the monitoring unit 350, and control instructions are issued through the safety protection unit 340 to ensure the safety of personnel, equipment and facilities in the gravity energy storage device 420 and the wind farm 410. When the gravity energy storage device 420 reaches full energy storage, the master control system 430 issues a command to the sub-control system 300 to terminate the current energy storage operation of the gravity energy storage device and issues another energy storage operation command to a gravity energy storage device 420 that has already discharged energy. The operation controller 320 of the sub-control system 300 of the gravity energy storage device 420 that receives the energy storage operation command activates the corresponding number of energy storage working units 100 in the gravity energy storage device 420. When the power generation value of the wind farm 410 does not meet the starting power of any energy storage working unit 100 in the gravity energy storage device 420, the master control system 430 issues a command to the wind farm control system 413 to control the wind power collection system 412 to cut off the power cable 440. At the same time, the master control system 430 issues a command to the sub-control system 300 of the gravity energy storage device 420 that is currently performing energy storage operation to shut down the energy storage working unit 100 that is currently performing energy storage operation.

During the energy release operation: the main control system 430 preferentially sends the energy release demand instruction of the main power grid 500 to a gravity energy storage device 420 that has stored energy at full load. The gravity energy storage device 420 begins the energy release operation, and the operation controller 320 of its sub-control system 300 controls the closing switch 127, and the corresponding energy storage working unit 100 begins the energy release operation. During the energy release operation, the main control system 430 obtains various data of the gravity energy storage device 420 and the wind farm 410 in real time through the communication interface circuit 360 and issues control instructions. The real-time status of the gravity energy storage device 420 and the wind farm 410 is obtained through the monitoring unit 350. Safety control instructions are issued through the safety protection unit 340 to ensure the safety of personnel, equipment and facilities within the gravity energy storage device 420 and the wind farm 410. The main power grid 500 is connected through the boost control device 450. The boost control device 450 is responsible for increasing the voltage of the power generation system to a voltage value acceptable to the main power grid until the energy release is completed. When the gravity energy storage device 420 finishes releasing energy, the overall control system 430 sends the current energy release demand instruction of the main grid 500 to another gravity energy storage device 420 that has fully stored energy, and the power generation system continues to generate electrical energy until all the gravity energy storage devices 420 of the power generation system 400 can no longer meet the power supply demand of the main grid 500. The overall control system 430 controls the boost control device 450 to disconnect the power cable 440 between the main grid 500 and the main grid 500.

Power generation system 400 includes at least one wind farm 410 (or photovoltaic farm (which has a similar layout and function to wind farm 410 in this power generation system)) and is equipped with multiple, or even dozens, of gravity energy storage devices 420. Each gravity energy storage device can store at least two hours of wind farm 410's (or photovoltaic farm's) rated power. Power generation system 400 can address harmonic interference and unstable output caused by natural wind (or photovoltaic) power generation on the main power grid.

Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" 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 disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

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

Claims (13)

A gravity energy storage device based on a group of abandoned oil, gas and water wells, characterized by comprising a sub-control system and a plurality of energy storage working units, each energy storage working unit being connected to the sub-control system via a control cable; The energy storage working unit includes an abandoned oil, gas and water well and a gravity energy storage device, wherein the gravity energy storage device includes a weight, a suspension mechanism, a first transmission and a generator motor connected in sequence, wherein the generator motor is connected to the power cable of the wind or photovoltaic power generation system through a power cable, and the height of the weight in the abandoned oil, gas and water well is changed by the suspension mechanism to achieve energy storage and release; The sub-control system is used to open or close a corresponding number of the energy storage working units according to the energy storage or release capacity requirements of the overall control system of the wind or photovoltaic power generation system, control and monitor the equipment status in each energy storage working unit, transmit the status and parameters of the gravity energy storage device to the overall control system, and re-regulate the gravity energy storage device according to the instructions issued by the overall control system. The gravity energy storage device according to claim 1 is characterized in that the abandoned oil, gas and water well is a well that has been abandoned after the exploitation of underground gas and liquid including oil, natural gas and groundwater, and has a depth of more than 200 meters. The gravity energy storage device according to claim 1 or 2 is characterized in that the weight is made of a material with a mass of more than 5,000 kilograms and an average density of more than 3,000 kilograms per cubic meter, and a safety distance should be reserved between the lowest and highest positions of the weight in the well and the bottom and wellhead respectively. The gravity energy storage device according to any one of claims 1 to 3 is characterized in that the suspension mechanism includes a wire rope, a fixed pulley, a drum and a drum brake, one end of the wire rope is fixedly connected to the top of the weight, and the other end passes around the fixed pulley above the wellhead and is wound on the drum located on one side of the wellhead, the drum is sleeved on the drum shaft, one end of the drum shaft is connected to the low-speed shaft of the first transmission, the high-speed shaft of the first transmission is connected to the generator motor, a switch is provided on the power cable, and the drum brake, switch and generator motor are connected to the sub-control system through the control cable. The gravity energy storage device according to claim 4 is characterized in that a load stabilizer is provided at the other end of the drum shaft, and the load stabilizer eliminates the influence of the gravity change of the wire rope in the well on the torque of the drum and the generator motor by absorbing and releasing elastic potential energy. The gravity energy storage device according to claim 5 is characterized in that the load stabilizer includes an elastic element and a second transmission, the other end of the reel shaft is connected to the high-speed shaft of the second transmission, and is transmitted to the elastic element after being decelerated by the second transmission, and the elastic element gradually changes the torque on the reel and the generator motor in a linear manner, so that the torque acting on the reel and the generator motor remains constant. The gravity energy storage device according to claim 6 is characterized in that the elastic element is a coil spring with linear characteristics, and the second transmission is a planetary transmission. The gravity energy storage device according to any one of claims 1 to 7 is characterized in that the sub-control system includes a first operation controller and a depth sensor, a first grid-connected control unit, a first safety protection unit, a first monitoring unit, a first communication interface circuit and a first user interface connected thereto; the depth sensor is used to detect the depth of the heavy object in the well; the first grid-connected control unit is used to connect the electric energy generated by the gravity energy storage device to the main power grid; the first safety protection unit is used to deal with emergencies, and when the parameters exceed the preset working range, the energy storage working unit with the problem is promptly shut down, or even the entire gravity energy storage device; the first monitoring unit is used to monitor the working status of the energy storage working unit in real time and transmit data to the first operation control unit, the first safety protection unit and the first user interface; the first communication interface circuit is used to realize data communication; the first user interface is used to input user instructions, change parameters, and display the operating status, data and fault conditions of the gravity energy storage device; the first operation controller is used for operation monitoring of the gravity energy storage device, including start and stop control, control of various electronic components and grid monitoring. The gravity energy storage device according to any one of claims 1 to 8 is characterized in that the sub-control system controls the working mode of each energy storage working unit according to the energy storage and release instructions of the overall control system of the wind or photovoltaic power generation system: when the wind farm or photovoltaic power generation site generates less power, the overall control system instructs the sub-control system of the gravity energy storage device to start a single or multiple energy storage working units to participate in energy storage; when the power generation of the wind farm or photovoltaic power generation site is close to full load, the overall control system instructs the sub-control system to start all energy storage working units to participate in energy storage at the same time; when the power generation of the wind farm or photovoltaic power generation site gradually increases, the overall control system instructs the sub-control system to start a single or multiple energy storage working units to participate in energy storage in succession. The gravity energy storage device according to any one of claims 1 to 9, wherein the operation process thereof comprises: During energy storage operation: the sub-control system opens the gravity energy storage equipment of the corresponding number of energy storage working units according to the energy storage capacity requirements of the overall control system. In the gravity energy storage equipment of the opened energy storage working units, the sub-control system first starts the suspension mechanism, and then connects the power cable to start the generator motor, and uses the suspension mechanism to lift the heavy object that is at the lower predetermined depth of the well or has not yet reached the upper predetermined depth of the well; when the heavy object reaches the upper predetermined depth of the adjacent well, the sub-control system first disconnects the power cable, brakes the generator motor to reduce its rotation speed, and then controls the suspension mechanism to reduce the lifting speed of the heavy object; when the heavy object reaches the upper predetermined depth of the well, the sub-control system controls the suspension mechanism to keep the height of the heavy object unchanged, thereby realizing the conversion of excess electrical energy into heavy objects. gravitational potential energy and stores it; if there is still surplus electrical energy to be stored, the sub-control system will continue to open the gravity energy storage equipment of the remaining energy storage working units until the entire gravity energy storage device lifts the weights in all energy storage working units to the upper predetermined depth of the well, achieving full-load energy storage and the energy storage operation is completed; when a single or part of the energy storage workstations are in the energy storage process and there is an unexpected lack of energy storage capacity, the sub-control system will disconnect the power cable, brake the generator motor to reduce its speed, and then control the suspension mechanism to make the weight in the well hover at the current position, and the energy storage operation will be suspended. If there is subsequent energy storage requirement, the energy storage working unit whose energy storage operation has been suspended will continue the energy storage operation until the weight reaches the upper predetermined depth of the well, achieving full-load energy storage of the energy storage working unit, and finally achieving full-load energy storage of the gravity energy storage device; During the energy release operation: the sub-control system opens the gravity energy storage devices of the corresponding number of energy storage working units according to the required energy release capacity. In the gravity energy storage devices of the opened energy storage working units, the sub-control system first connects the power cable to start the generator motor, and then controls the suspension mechanism to continuously lower the weight in the well by releasing the wire rope; when the weight reaches the lower predetermined depth of the well, the sub-control system disconnects the power cable, brakes the generator motor to reduce its rotation speed, and then controls the suspension mechanism to reduce the descent speed of the weight; when the weight reaches the lower predetermined depth of the well, the sub-control system controls the suspension mechanism to keep the height of the weight unchanged, thereby realizing the conversion of the gravitational potential energy of the weight into electrical energy; if the gravity storage If the energy storage device still has energy release requirements, the control system will open the gravity energy storage equipment of the remaining corresponding number of energy storage working units until the entire gravity energy storage device lowers the weights in all energy storage working units to the lower predetermined depth of the well to achieve full-load energy release; when a single or part of the energy storage working units are in the process of releasing energy and an unexpected situation occurs where energy release is not required, the sub-control system will first disconnect the power cable and brake the generator motor to reduce its speed, and then control the suspension structure to make the weight in the well hover at the current position, and the energy release operation will be suspended. If there is a subsequent energy release requirement, the energy storage working unit whose energy release operation has been suspended will continue the energy release operation until the weight reaches the lower predetermined depth of the well, thereby achieving full-load energy release of the energy storage working unit and finally achieving full-load energy release of the gravity energy storage device. A power generation system, characterized in that the power generation system is a wind or photovoltaic power generation system, comprising a master control system and at least one wind or photovoltaic power plant that supplies power to a main power grid through a gravity energy storage device, the gravity energy storage device adopts a gravity energy storage device according to any one of claims 1 to 10, and a boost control device is further connected between the gravity energy storage device and the main power grid; each wind or photovoltaic power plant is configured with at least three gravity energy storage devices, the maximum rated power generation power of the wind or photovoltaic power plant is equal to the energy storage power of one gravity energy storage device, when the wind or photovoltaic power plant is generating electricity, one gravity energy storage device performs energy storage operation, one gravity energy storage device performs energy release operation, and at least one gravity energy storage device is in a full-load energy storage state; the sub-control systems in the wind or photovoltaic power plant and each gravity energy storage device are connected to the master control system via control cables, and power is transmitted between the wind or photovoltaic power plant, the gravity energy storage device and the main power grid via power cables; The overall control system is used to open and close the corresponding gravity energy storage device to store energy and output electrical energy to the main power grid according to the power generation and operating conditions of the wind or photovoltaic power plant, and to monitor the operating conditions of the power generation system. The power generation system according to claim 11 is characterized in that the general control system includes a second operation controller and a second grid-connected control unit, a second safety protection unit, a second monitoring unit, a second communication interface circuit and a second user interface connected thereto; the second grid-connected control unit is used to connect the electric energy generated by the gravity energy storage device to the main power grid; the second safety protection unit is used to deal with emergencies, and when the parameters exceed the preset working range, the energy storage working unit with the problem, or even the entire gravity energy storage device, is shut down in time; the second monitoring unit is used to monitor the working status of the energy storage working unit in real time and transmit the data to the second operation control unit, the second safety protection unit and the second user interface; the second communication interface circuit is used to realize data communication; the second user interface is used to input user instructions, change parameters, and display the operating status, data and fault conditions of the gravity energy storage device; the second operation controller is used for operation monitoring of the power generation system, including start and stop control, control of various electronic devices and grid monitoring. The power generation system according to claim 11 or 12, wherein the operation process of the power generation system includes: During energy storage operation: the control system of the wind power or photovoltaic power plant sends the value of the wind power or photovoltaic power generation power that can be achieved and the power generation power scale in the future to the general control system in real time, and the general control system sends an energy storage operation instruction to a gravity energy storage device that is not in full load energy storage, and the sub-control system of the gravity energy storage device starts the corresponding number of energy storage working units in the gravity energy storage device. At the same time, the general control system sends an instruction to the control system of the wind power or photovoltaic power plant, connects the power cable between the wind power or photovoltaic power plant and the gravity energy storage device, and the gravity energy storage device that receives the energy storage operation instruction starts energy storage. During the energy storage operation, the general control system obtains various data of the gravity energy storage device and the wind power or photovoltaic power plant in real time and sends control instructions. When the gravity energy storage device that performs the energy storage operation When the energy storage device reaches full load energy storage, the main control system sends an instruction to the sub-control system to end the current energy storage operation of the gravity energy storage device, and sends an energy storage operation instruction again to a gravity energy storage device that has completed energy release. The gravity energy storage device that receives the energy storage operation instruction starts the corresponding number of energy storage working units in the gravity energy storage device through the sub-control system; when the power generation value of the wind power or photovoltaic power plant cannot meet the starting power of any energy storage working unit in the gravity energy storage device, the main control system sends an instruction to the control system of the wind power or photovoltaic power plant to cut off the power cable between the wind power or photovoltaic power plant and the gravity energy storage device, and at the same time, the main control system sends an instruction to the sub-control system of the gravity energy storage device that is performing energy storage operation to shut down the energy storage working unit that is performing energy storage operation; During energy release operation: the general control system preferentially sends the energy release demand instruction of the main power grid to a gravity energy storage device that has fully stored energy. The gravity energy storage device starts the energy release operation, and its sub-control system activates the corresponding energy storage working unit to start the energy release operation. During the energy release operation, the general control system obtains various data of the gravity energy storage device and the wind or photovoltaic power plant in real time and issues control instructions. When the gravity energy storage device finishes releasing energy, the general control system sends the current energy release demand instruction of the main power grid to another gravity energy storage device that has fully stored energy. The power generation system continues to generate electricity until all gravity energy storage devices in the power generation system can no longer meet the power supply demand of the main power grid. The general control system controls the boost control device to disconnect the power cable between the gravity energy storage device and the main power grid.