Gravity-flywheel-commutation equipment ternary hybrid energy storage system and intelligent power grid

Abstract

The invention provides a gravity-flywheel-converter device ternary hybrid energy storage system and a smart grid, and the system comprises a gravity energy storage device, a flywheel energy storage device and a power electronic converter device which are electrically connected with the grid. The system further comprises a main controller which is in communication connection with the gravity energy storage device, the flywheel energy storage device, the power electronic conversion device and the power grid, and the main controller is used for controlling discharge of a capacitor in the power electronic conversion device, discharge of the flywheel energy storage device and discharge of the gravity energy storage device under the condition that an emergency instruction sent by the power grid is received. The starting moment of discharging of the flywheel energy storage equipment is before the cut-off moment of discharging of the power electronic converter equipment, and the starting moment of discharging of the gravity energy storage equipment is before the cut-off moment of discharging of the flywheel energy storage equipment. The problem that in the prior art, a single energy storage technology cannot meet the requirement of a novel power system for continuous power support of multiple time scales is solved.

Description

Technical Field

[0001] The present application relates to the field of electrical technology, and in particular to a gravity-flywheel-commutation device ternary hybrid energy storage system and a smart grid. Background Art

[0002] With the development of new energy technologies, a large amount of renewable energy generation is being integrated into the power system via power electronic converters, further changing the structure of the power system. These new power systems, when coping with complex scenarios such as weak power grids, high penetration of new energy sources, and extreme weather, place higher demands on the safety, active support characteristics, response speed, and continuous charge and discharge time of power supply and energy storage systems. Existing technologies in these new power systems cannot meet the requirements of continuous power support over multiple timescales with a single energy storage technology. Summary of the Invention

[0003] The main purpose of this application is to provide a gravity-flywheel-commutation device ternary hybrid energy storage system and smart grid, so as to at least solve the problem in the existing technology that a single energy storage technology cannot meet the continuous power support requirements of the new power system on multiple time scales.

[0004] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a gravity-flywheel-commutation device ternary hybrid energy storage system is provided, wherein the gravity-flywheel-commutation device ternary hybrid energy storage system includes: a gravity energy storage device for being electrically connected to a power grid; a flywheel energy storage device for being electrically connected to the power grid; a power electronic commutation device for being electrically connected to the power grid, wherein the power electronic commutation device includes a capacitor; a main controller, which is communicatively connected to the gravity energy storage device, the flywheel energy storage device, the power electronic commutation device and the power grid respectively, and is used to control the discharge of the capacitor in the power electronic commutation device, the discharge of the flywheel energy storage device and the discharge of the gravity energy storage device in the power electronic commutation device to transmit electric energy to the power grid when receiving an emergency instruction sent by the power grid, wherein the emergency instruction indicates that the power grid has failed and needs to be charged; wherein the start time of discharge of the flywheel energy storage device is before the end time of discharge of the power electronic commutation device, and the start time of discharge of the gravity energy storage device is before the end time of discharge of the flywheel energy storage device.

[0005] Optionally, the power electronic commutation device further includes a DC bus, and the DC bus is used to connect the power grid and the gravity energy storage device, and the power grid and the flywheel energy storage device.

[0006] Optionally, the main controller is also used to: upon receiving a power surplus instruction sent by the power grid, respectively obtain the current energy levels of the flywheel energy storage device, the gravity energy storage device and the power electronic commutation device, the power surplus instruction representing an instruction indicating that the power grid has a power surplus; when the current energy level of the flywheel energy storage device is less than a preset first energy threshold, control the flywheel energy storage device to obtain electrical energy from the power grid to complete energy storage; when the current energy level of the gravity energy storage device is less than a preset second energy threshold, control the gravity energy storage device to obtain electrical energy from the power grid to complete energy storage; when the current energy level of the power electronic commutation device is less than a preset third energy threshold, control the power electronic commutation device to obtain electrical energy from the power grid to complete energy storage.

[0007] Optionally, the gravity energy storage device includes: an energy storage object; a gravity energy storage drive structure, mechanically connected to the energy storage object; a gravity energy storage controller, electrically connected to the gravity energy storage drive structure and communicatively connected to the main controller, and the gravity energy storage controller is used to control the gravity energy storage drive structure to drive the energy storage object to move downward upon receiving a first control instruction or a second control instruction; wherein, the first control instruction is an instruction sent by the main controller when it receives the emergency instruction, and the second control instruction is an instruction sent by the main controller when it receives a power shortage instruction sent by the power grid, and the power shortage instruction represents an instruction indicating that the power grid has a power shortage.

[0008] Optionally, the flywheel energy storage device includes: a rotor structure; a flywheel energy storage drive structure, mechanically connected to the rotor structure; a flywheel energy storage controller, electrically connected to the flywheel energy storage drive structure and communicatively connected to the main controller, and the flywheel energy storage controller is used to control the flywheel energy storage drive structure to drive the rotation of the rotor structure to decelerate when receiving a third control instruction or a fourth control instruction; wherein the third control instruction is an instruction sent by the main controller when it receives the emergency instruction, and the fourth control instruction is an instruction sent by the main controller when it receives a power shortage instruction sent by the power grid and monitors that the output power of the gravity energy storage device is less than the target power, the power shortage instruction represents an instruction indicating that the power grid has a power shortage, and the target power represents the power that the power grid needs to supplement.

[0009] Optionally, the power electronic commutation device also includes: a power electronic controller, electrically connected to the capacitor and communicatively connected to the main controller, the power electronic controller being used to control the capacitor to discharge when a fifth control instruction is received, wherein the fifth control instruction is an instruction sent by the main controller when it receives the emergency instruction.

[0010] Optionally, the main controller is also used to: when receiving a power shortage instruction sent by the power grid and monitoring that the sum of the output powers of the gravity energy storage device and the flywheel energy storage device is less than the target power, send a sixth control instruction to the power electronic controller so that the power electronic controller controls the capacitor to discharge, the power shortage instruction represents an instruction indicating that the power grid has a power shortage, and the target power represents the power that the power grid needs to supplement.

[0011] Optionally, controlling the discharge of the capacitor in the power electronic commutation device, the discharge of the flywheel energy storage device, and the discharge of the gravity energy storage device includes: controlling the capacitor in the power electronic commutation device to start discharging; determining whether the output power of the power electronic commutation device begins to decrease; in the case where the output power of the power electronic commutation device begins to decrease, controlling the flywheel energy storage device to start discharging; determining whether the sum of the output powers of the flywheel energy storage device and the power electronic commutation device begins to decrease; in the case where the sum of the output powers of the flywheel energy storage device and the power electronic commutation device begins to decrease, controlling the gravity energy storage device to start discharging, so that the curve of the total output power of the gravity-flywheel-commutation device ternary hybrid energy storage system is a monotonically increasing function, wherein the total output power is the sum of the output power of the power electronic commutation device, the output power of the flywheel energy storage device, and the output power of the gravity energy storage device.

[0012] According to another aspect of the present application, a smart grid is provided, comprising: any one of the gravity-flywheel-commutation device ternary hybrid energy storage systems.

[0013] Applying the technical solution of the present application, the gravity-flywheel-commutation device ternary hybrid energy storage system includes a gravity energy storage device, a flywheel energy storage device and a power electronic commutation device for being electrically connected to the power grid, and also includes a main controller that is communicatively connected to the gravity energy storage device, the flywheel energy storage device, the power electronic commutation device and the power grid respectively. The main controller is used to control the discharge of the capacitor in the power electronic commutation device, the discharge of the flywheel energy storage device and the discharge of the gravity energy storage device when receiving an emergency instruction sent by the power grid, so as to transmit electric energy to the power grid, wherein the start time of the discharge of the flywheel energy storage device is before the end time of the discharge of the power electronic commutation device, and the start time of the discharge of the gravity energy storage device is before the end time of the discharge of the flywheel energy storage device. Compared with the problem in the prior art that a single energy storage technology cannot meet the continuous power support requirements of the new power system on multiple time scales, in this application, when the main controller receives the emergency command sent by the power grid, the capacitor in the power electronic commutation device can respond quickly and start discharging, providing instantaneous power support. This is the fastest first-level response to the power grid, ensuring the system's immediate response to grid emergencies; the flywheel energy storage device starts discharging before the power electronic commutation device finishes discharging, and can seamlessly connect after the short power support provided by the power electronic commutation device, extending the power output time to support at the second to minute level; the gravity energy storage device serves as the third-level storage Energy resources, the response time is relatively long, but it starts discharging before the flywheel energy storage device is fully discharged, and can provide hourly level power support for the power grid, which is an effective support for large-scale energy demand and the key to solving long-term power shortages; the gravity-flywheel-commutation equipment ternary hybrid energy storage system of the present application can form multi-level and multi-time scale power support through the fast-starting capacitor, the subsequent flywheel energy storage and the subsequent gravity energy storage when the power grid encounters an emergency, effectively alleviating the power shortage during the power grid failure, enhancing the resilience and stability of the power grid, not only improving the rapid response capability to power grid failures, but also maintaining stable power output for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings that constitute part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0015] Figure 1 A structural block diagram of a gravity-flywheel-commutation device ternary hybrid energy storage system provided in an embodiment of the present application is shown;

[0016] Figure 2 A schematic diagram of a control flow of a gravity-flywheel-commutation device ternary hybrid energy storage system according to an embodiment of the present application is shown;

[0017] Figure 3A schematic diagram of energy release and response time of each device in a gravity-flywheel-commutation device ternary hybrid energy storage system provided according to an embodiment of the present application is shown;

[0018] Figure 4 A schematic diagram of output power of a gravity-flywheel-commutation device ternary hybrid energy storage system in emergency mode is shown according to an embodiment of the present application;

[0019] Figure 5 A structural block diagram of another gravity-flywheel-commutation device ternary hybrid energy storage system provided according to an embodiment of the present application is shown.

[0020] The above drawings include the following reference numerals:

[0021] 100. Gravity-flywheel-commutation device ternary hybrid energy storage system; 101. Gravity energy storage device; 102. Power grid; 103. Flywheel energy storage device; 104. Power electronic commutation device; 105. DC bus; 106. AC bus; 107. Wind and solar power station. DETAILED DESCRIPTION

[0022] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0024] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0025] As introduced in the background technology, the single energy storage technology in the existing technology cannot meet the needs of the new power system for continuous power support on multiple time scales. To solve the above problems, the embodiments of the present application provide a gravity-flywheel-commutation device ternary hybrid energy storage system and a smart grid.

[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0027] The embodiment of the present application provides a gravity-flywheel-commutation device ternary hybrid energy storage system, such as Figure 1 As shown, the gravity-flywheel-commutation device ternary hybrid energy storage system 100 includes:

[0028] Gravity energy storage device 101, for electrical connection to power grid 102;

[0029] A flywheel energy storage device 103, configured to be electrically connected to the power grid 102;

[0030] A power electronic commutation device 104, configured to be electrically connected to the power grid 102, wherein the power electronic commutation device 104 includes a capacitor (not shown);

[0031] In actual application, those skilled in the art can flexibly select appropriate power electronic commutation equipment according to actual needs, and this application does not impose specific restrictions on this. In the embodiment of this application, the power electronic commutation equipment includes a modular multilevel converter (MMC).

[0032] a main controller (not shown), which is communicatively connected to the gravity energy storage device 101, the flywheel energy storage device 103, the power electronic commutation device 104, and the power grid 102, and is configured to control the discharge of the capacitor in the power electronic commutation device 104, the discharge of the flywheel energy storage device 103, and the discharge of the gravity energy storage device 101 upon receiving an emergency command from the power grid 102, so as to transmit electric energy to the power grid 102, wherein the emergency command indicates that the power grid 102 has failed and needs to be charged;

[0033] The start time of discharge of the flywheel energy storage device 103 is before the end time of discharge of the power electronic commutation device 104 , and the start time of discharge of the gravity energy storage device 101 is before the end time of discharge of the flywheel energy storage device 103 .

[0034] Through the above embodiments, the gravity-flywheel-commutation device ternary hybrid energy storage system includes a gravity energy storage device, a flywheel energy storage device and a power electronic commutation device for being electrically connected to the power grid, and also includes a main controller that is communicatively connected to the gravity energy storage device, the flywheel energy storage device, the power electronic commutation device and the power grid respectively. The main controller is used to control the discharge of the capacitor in the power electronic commutation device, the discharge of the flywheel energy storage device and the discharge of the gravity energy storage device when receiving an emergency instruction sent by the power grid, so as to transmit electric energy to the power grid, wherein the start time of the discharge of the flywheel energy storage device is before the end time of the discharge of the power electronic commutation device, and the start time of the discharge of the gravity energy storage device is before the end time of the discharge of the flywheel energy storage device. Compared with the problem in the prior art that a single energy storage technology cannot meet the continuous power support requirements of the new power system on multiple time scales, in this application, when the main controller receives the emergency command sent by the power grid, the capacitor in the power electronic commutation device can respond quickly and start discharging, providing instantaneous power support. This is the fastest first-level response to the power grid, ensuring the system's immediate response to grid emergencies; the flywheel energy storage device starts discharging before the power electronic commutation device finishes discharging, and can seamlessly connect after the short power support provided by the power electronic commutation device, extending the power output time to support at the second to minute level; the gravity energy storage device serves as the third-level storage Energy resources, the response time is relatively long, but it starts discharging before the flywheel energy storage device is fully discharged, and can provide hourly level power support for the power grid, which is an effective support for large-scale energy demand and the key to solving long-term power shortages; the gravity-flywheel-commutation equipment ternary hybrid energy storage system of the present application can form multi-level and multi-time scale power support through the fast-starting capacitor, the subsequent flywheel energy storage and the subsequent gravity energy storage when the power grid encounters an emergency, effectively alleviating the power shortage during the power grid failure, enhancing the resilience and stability of the power grid, not only improving the rapid response capability to power grid failures, but also maintaining stable power output for a long time.

[0035] It should be noted that modular multilevel converters (MMCs) are a widely used technology in long-distance, high-capacity HVDC transmission systems. Due to their inherently large internal capacitors, they possess intrinsic energy storage properties and extremely fast operation characteristics. However, due to the limited amount of energy stored in the capacitors, the energy storage duration is extremely short, typically less than one second. Flywheel energy storage is relatively simple in principle and mature in technology. Recent research has proposed flywheel array applications, offering greater flexibility in power system applications. Flywheel energy storage devices feature high-power charging and discharging characteristics, fast response times, large mechanical inertia, and long charge and discharge times. They are widely used in power system frequency regulation and inertial support applications. Gravity energy storage offers advantages such as a simple principle, flexible site selection, large capacity, and high efficiency. Existing gravity energy storage technologies include a variety of types and modular scalability, allowing for flexible deployment in multiple application scenarios to meet diverse energy storage needs. They are expected to be widely used in new power systems. Gravity energy storage has a response time of seconds to minutes, and charge and discharge times can be flexibly adjusted from hours to days. Although single-cell energy storage technologies with good performance and intrinsic safety such as the above are relatively mature, they cannot solve all problems of the power system in application due to constraints such as configuration and control, resulting in a lot of waste. Therefore, in response to the demand for energy storage systems in new power systems, a gravity-flywheel-commutation device ternary hybrid energy storage system with full time scale and active support characteristics and safety is urgently needed.

[0036] To meet the energy storage technology needs of new power systems, this application proposes and constructs a ternary gravity-flywheel-commutation hybrid energy storage system consisting of power electronic commutation equipment, flywheel energy storage equipment, and gravity energy storage equipment, and proposes a corresponding control strategy. Through collaborative design, this system achieves precise response to energy storage needs at multiple time scales: the power electronic commutation equipment provides transient fault support and voltage / frequency stability with millisecond response, the flywheel energy storage equipment, with its high power characteristics, meets the frequency regulation and ancillary service needs of seconds to minutes, and the gravity energy storage equipment, with its large capacity advantage, undertakes energy time shifting and large-scale renewable energy consumption tasks at the hourly level or above.

[0037] In one option, Figure 1 As shown, the power electronic commutation device 104 further includes a DC bus 105, which is used to connect the power grid 102 with the gravity energy storage device 101, and the power grid 102 with the flywheel energy storage device 103. In this embodiment, the DC bus serves as a common energy collection point, ensuring efficient energy transfer between the power electronic commutation device, flywheel energy storage, and gravity energy storage, simplifying the system structure and reducing costs. Through the integration of the DC bus, the coordinated operation of the hybrid energy storage system is achieved.

[0038] Specifically, the electric energy of the gravity energy storage device and the flywheel energy storage device is exchanged with the power grid through the power electronic commutation device.

[0039] In an exemplary embodiment, the main controller is further configured to: upon receiving a power surplus instruction sent by the power grid, respectively obtain the current energy levels of the flywheel energy storage device, the gravity energy storage device and the power electronic commutation device, the power surplus instruction representing an instruction indicating that the power grid has a power surplus; when the current energy level of the flywheel energy storage device is less than a preset first energy threshold, control the flywheel energy storage device to obtain electrical energy from the power grid to complete energy storage; when the current energy level of the gravity energy storage device is less than a preset second energy threshold, control the gravity energy storage device to obtain electrical energy from the power grid to complete energy storage; when the current energy level of the power electronic commutation device is less than a preset third energy threshold, control the power electronic commutation device to obtain electrical energy from the power grid to complete energy storage. In this embodiment, the main controller monitors the energy status of each device in real time, and can accurately control energy storage when the power grid has a power surplus, fully utilize the power surplus of the power grid, provide sufficient energy reserves for the energy storage of each device, avoid energy waste, improve the utilization rate of the energy storage system, and enhance the response capability and continuous power supply capability of the subsequent system in emergency situations.

[0040] Specifically, the current energy level of a flywheel energy storage device can be reflected by the rotation speed of the rotor structure, the current energy level of a gravity energy storage device can be reflected by the height of the energy storage object, and the current energy level of a power electronic commutation device can be reflected by the voltage or current of the capacitor.

[0041] In actual application, those skilled in the art may set the first energy threshold, the second energy threshold and the third energy threshold based on empirical values, or obtain them through multiple experiments, and this application does not impose any specific restrictions on this.

[0042] In other embodiments, the gravity energy storage device includes: an energy storage object; a gravity energy storage drive structure, which is mechanically connected to the energy storage object; a gravity energy storage controller, which is electrically connected to the gravity energy storage drive structure and is communicatively connected to the main controller, and the gravity energy storage controller is used to control the gravity energy storage drive structure to drive the energy storage object to move downward when receiving a first control instruction or a second control instruction; wherein the first control instruction is an instruction sent by the main controller when it receives the emergency instruction, and the second control instruction is an instruction sent by the main controller when it receives a power shortage instruction sent by the power grid, and the power shortage instruction represents an instruction indicating that the power grid has a power shortage. In this embodiment, when the gravity energy storage controller receives the first control instruction or the second control instruction, that is, when the power grid needs to supplement electric energy, the energy release of the gravity energy storage device provides continuous high-power support for the power system, further improving the stability of the power grid.

[0043] Specifically, the power shortage instruction refers to an instruction indicating that the power grid only has a power shortage but no fault occurs.

[0044] Specifically, gravity energy storage equipment realizes the mutual conversion of electrical energy and gravitational potential energy by transferring energy storage objects between upper and lower yards, providing the system with large-capacity, long-term energy storage and release capabilities.

[0045] Specifically, the gravity energy storage equipment includes: a gravity energy storage upper yard, a gravity energy storage lower yard, a gravity energy storage channel, a gravity energy storage drive structure, a gravity energy storage transmission structure, a gravity energy storage controller, a gravity energy storage protection structure, necessary automatic operation structures, gravity energy storage measurement and auxiliary structures, and energy storage objects. The gravity energy storage channel connects the upper gravity energy storage yard with the lower gravity energy storage yard, and is the channel for the operation of energy storage objects; the gravity energy storage controller is electrically connected to the gravity energy storage drive structure to control the rotation of the gravity energy storage drive structure to complete the mutual conversion of electrical energy and kinetic energy; the gravity energy storage drive structure is mechanically connected to the gravity energy storage transmission structure to transfer the kinetic energy of the energy storage drive structure and the kinetic energy of the energy storage object; the gravity energy storage protection structure is located in the gravity energy storage transmission structure, and is used to protect the energy storage object and other structures of the equipment in the event of a fault; the automatic operation structure is located in the upper gravity energy storage yard and the lower gravity energy storage yard, and is used to perform functions such as stacking, pre-acceleration and deceleration of energy storage objects; the measurement and auxiliary structures are located in each structure of the gravity energy storage equipment to measure various physical quantities and auxiliary functions such as communication.

[0046] Specifically, gravity energy storage equipment achieves the mutual conversion between electrical energy and gravitational potential energy by transferring energy storage objects between upper and lower yards. When the gravity energy storage device operates in the energy storage operation mode, the gravity energy storage drive structure obtains electric energy from the power grid to drive the gravity energy storage transmission structure. At the same time, the energy storage object is pushed out from the lower gravity energy storage yard through the automatic operation structure into the gravity energy storage channel and lifted upward through the gravity energy storage transmission structure until the energy storage object reaches the upper gravity energy storage yard and is stacked by the automatic operation structure. In this process, the electric energy in the power grid is converted into the gravitational potential energy of the energy storage object through the gravity energy storage device for storage; when the gravity energy storage device operates in the energy release operation mode, the energy storage object is pushed out from the upper gravity energy storage yard through the automatic operation structure into the gravity energy storage channel and drives the gravity energy storage transmission structure to run downward until the energy storage object reaches the lower gravity energy storage yard and is stacked by the automatic operation structure. At the same time, the gravity energy storage drive structure drives the gravity energy storage transmission structure to rotate, thereby converting kinetic energy into electric energy and feeding back to the power grid; in this process, the gravitational potential energy of the energy storage object is converted into electric energy through the gravity energy storage device. During the energy storage and release process, the gravity energy storage controller controls the mechanical movement and electrical characteristics of the gravity energy storage device, and the gravity energy storage protection structure detects abnormal conditions of the gravity energy storage device and protects the gravity energy storage device.

[0047] According to some exemplary embodiments of the present application, the flywheel energy storage device includes: a rotor structure; a flywheel energy storage drive structure, which is mechanically connected to the rotor structure; a flywheel energy storage controller, which is electrically connected to the flywheel energy storage drive structure and is communicatively connected to the main controller, and the flywheel energy storage controller is used to control the flywheel energy storage drive structure to drive the rotation of the rotor structure to decelerate when receiving a third control instruction or a fourth control instruction; wherein the third control instruction is an instruction sent by the main controller when receiving the emergency instruction, and the fourth control instruction is an instruction sent by the main controller when receiving the power shortage instruction sent by the power grid and monitoring that the output power of the gravity energy storage device is less than the target power, the power shortage instruction represents an instruction indicating that the power grid has a power shortage, and the target power represents the power that the power grid needs to supplement. In this embodiment, the flywheel energy storage device can quickly respond to the third control instruction or the fourth control instruction, that is, when an emergency or power shortage occurs in the power grid, it can quickly start discharging and provide the required power.

[0048] Specifically, flywheel energy storage devices achieve rapid energy storage and release through a high-speed rotating rotor structure. When releasing energy, the rotor structure's speed decreases, converting kinetic energy into electrical energy to power the grid. When storing energy, the flywheel energy storage device draws electrical energy from the grid, increasing the rotor structure's speed and converting electrical energy into kinetic energy for storage.

[0049] Specifically, when the main controller receives a power shortage instruction, the gravity energy storage device discharges first. When the discharge cannot meet the power demand of the power grid, the flywheel energy storage device discharges secondarily.

[0050] Specifically, a flywheel energy storage device includes a rotor structure, a bearing structure, a drive motor (i.e., the flywheel energy storage drive structure), an inverter, a vacuum chamber, and a flywheel energy storage controller. The rotor structure is the core component of the flywheel energy storage device, storing kinetic energy through high-speed rotation. The bearing structure connects and secures the rotor structure to the flywheel housing. The bearing structure should have low friction to ensure high overall efficiency. The inverter is electrically connected to the drive motor, driving the rotor structure to rotate, thereby converting electrical energy into kinetic energy. The vacuum chamber surrounds the rotor structure, providing a vacuum environment and reducing friction losses.

[0051] Specifically, flywheel energy storage devices convert electrical energy into kinetic energy by controlling the acceleration and deceleration of the rotor structure. As a typical power-type energy storage system, flywheel energy storage generally operates in a standby state of energy release. This means that the rotor structure maintains its rated speed under the control of the bearing structure, drive motor, inverter, vacuum chamber, and flywheel energy storage controller. Therefore, we will only analyze the energy release process of flywheel energy storage: when the grid experiences a power shortage (i.e., the grid issues a power shortage command) or an emergency (i.e., the grid issues an emergency command), the rotor structure begins to decelerate under the control of the inverter and drive motor. The kinetic energy stored in the rotor structure is converted into electrical energy through the drive motor and inverter and fed back to the grid.

[0052] According to other exemplary embodiments of the present application, the power electronic commutation device further includes: a power electronic controller electrically connected to the capacitor and communicatively connected to the master controller, the power electronic controller being configured to control the discharge of the capacitor upon receipt of a fifth control instruction, wherein the fifth control instruction is a command sent by the master controller upon receipt of the emergency instruction. In this embodiment, upon receiving the fifth control instruction, the power electronic controller can effectively respond to instantaneous power shortages in the power grid, providing instant power compensation to the power system through the rapid discharge of the power electronic commutation device, further enhancing the overall stability and reliability of the system.

[0053] In some other optional solutions of the present application, the main controller is also used to: when receiving the power shortage instruction sent by the power grid and monitoring that the sum of the output power of the gravity energy storage device and the flywheel energy storage device is less than the target power, send a sixth control instruction to the power electronic controller so that the power electronic controller controls the capacitor to discharge, the power shortage instruction represents the instruction of the power shortage of the power grid, and the target power represents the power that the power grid needs to supplement. In this embodiment, the main controller can intelligently decide whether to start the discharge of the power electronic commutation device by monitoring the power demand of the power grid and the output power of the gravity energy storage device and the flywheel energy storage device, thereby ensuring the precise matching of the overall power output of the system with the power grid demand.

[0054] Specifically, a modular multilevel converter (MMC) consists of submodules, bridge arm structures, phase units and topology, a control unit (i.e., a power electronic controller), and related auxiliary units. The topology of a three-phase MMC is generally a three-phase, six-bridge arm structure. Each phase unit consists of two upper and lower bridge arms, each of which is composed of multiple submodules, including capacitors. These submodules are the core of the MMC and typically utilize half-bridge or full-bridge topologies. The control unit controls the MMC through calculations, while related auxiliary units implement cooling, protection, measurement, and other functions.

[0055] Specifically, MMC, as a high-performance high-power power electronic converter, is widely used in large-scale power transmission projects such as high-voltage direct current transmission. When the MMC is operating normally, its bridge arm capacitors are in a charged state. Therefore, the bridge arm capacitors in each sub-module can be regarded as energy storage structures. Similar to flywheel energy storage devices, they are also in an energy release standby state. Similarly, only the energy release process is analyzed: when there is a power shortage, the control unit of the MMC controls the release of electrical energy in the capacitors in each bridge arm sub-module. This process is completed instantly upon receiving the fifth control instruction or the sixth control instruction, supporting the power grid at an extremely fast speed. At this time, the electrical energy stored in the capacitors is transferred to the power grid to realize the function of the energy storage device.

[0056] Specifically, the gravity-flywheel-commutation device ternary hybrid energy storage system of the present application adopts a hybrid energy storage control strategy with a hierarchical control strategy as the core, specifically a lower-level control strategy with each energy storage unit of flywheel energy storage equipment, gravity energy storage equipment, and power electronic commutation equipment as units and an upper-level control strategy dominated by the main controller. The upper-level control strategy acts on the main controller as a hub to control the energy exchange between the flywheel energy storage equipment, gravity energy storage equipment, power electronic commutation equipment and the power grid. The main controller receives the upper-level control instructions and sends them to each lower-level control strategy. The lower-level control strategy acts on each energy storage unit controller. In addition to responding to the upper-level control instructions, each energy storage unit controller also has the function of motor control.

[0057] Specifically, if Figure 2As shown, the gravity-flywheel-commutation device ternary hybrid energy storage system is in a standby state on a daily basis. When a power shortage occurs in the power grid (i.e., the power grid sends an emergency command or a power shortage command), the main controller generates control commands that act on the flywheel energy storage device, the gravity energy storage system device, and the MMC controller (i.e., the power electronic controller) respectively. The MMC (i.e., the power electronic commutation device) sends the electrical energy in the bridge arm capacitor into the power grid. After the flywheel energy storage device completes the startup process, it releases active power and is fed into the power grid through the MMC. After the gravity energy storage device completes the startup process, it also transmits active power to the power grid through the MMC. At this point, the gravity-flywheel-commutation device ternary hybrid energy storage system is fully started and can continuously supply active power to the power grid until a power surplus occurs in the power grid. After the flywheel energy storage device and the gravity energy storage device are charged, they re-enter the standby state of the gravity-flywheel-commutation device ternary hybrid energy storage system.

[0058] Specifically, the operating states of the gravity-flywheel-commutation device ternary hybrid energy storage system of the present application can be divided into two types: daily operation mode and emergency operation mode.

[0059] The daily operation mode is based on large-scale gravity energy storage equipment, primarily providing power transfer functionality for the gravity-flywheel-commutation hybrid energy storage system. During the daily operation mode, the gravity-flywheel-commutation hybrid energy storage system absorbs power from the grid via the power electronics commutation equipment to maintain DC bus voltage stability. The gravity energy storage drive and transmission structures transfer the energy storage objects from the lower storage yard to the upper storage yard, completing energy storage. During this process, through centralized control, the flywheel energy storage device handles power fluctuations during operation of the gravity energy storage device and smoothes the power in the gravity-flywheel-commutation hybrid energy storage system, thereby ensuring power stability within the gravity-flywheel-commutation hybrid energy storage system. During the energy release condition in the daily operation mode, the gravity-flywheel-commutation device ternary hybrid energy storage system sends electric energy to the grid through the power electronic commutation device to maintain the stability of the DC bus voltage. The energy storage object located in the upper yard falls through the energy storage transmission structure and drives the energy storage drive structure to rotate, thereby completing the energy release and power generation. In this process, through centralized control, the flywheel energy storage device handles the power fluctuations during the operation of the gravity energy storage device and smoothes the power in the gravity-flywheel-commutation device ternary hybrid energy storage system, thereby ensuring the power stability of the gravity-flywheel-commutation device ternary hybrid energy storage system.

[0060] The emergency operation mode is a working mode that responds quickly to sudden emergencies in the power grid and provides power support to ensure the safety and stability of the power grid. Emergency situations include sudden disconnection of generators in the power grid, sudden drop in renewable energy output, short circuit of transmission lines, disconnection of key connecting lines, sudden surge in load and system decoupling operation. There is a sudden power shortage in the power grid. At this time, the power grid sends an emergency command to the main controller. The function of the emergency operation mode is to quickly provide power to the power grid when an emergency occurs in the power grid. Since the emergency operation mode is only activated when an emergency occurs in the power grid, the gravity-flywheel-commutation equipment ternary hybrid energy storage system should be in standby status before an emergency occurs in the power grid. When an emergency occurs in the power grid, the upper-level control (i.e., the main controller) of the gravity-flywheel-commutation device ternary hybrid energy storage system receives instructions and responds, controlling the capacitor discharge and output of electrical energy in the power electronic commutation device. This process takes milliseconds to complete. At the same time, the flywheel energy storage device is started to transmit electrical energy to the power grid before the capacitor discharge in the power electronic commutation device is cut off. This process takes seconds. At the same time, the gravity energy storage device is started in energy release mode. Before the flywheel energy storage device is discharged, the gravity energy storage device generates electricity in energy release mode and feeds it into the power grid, providing long-term, high-power power support for the power grid. This process takes minutes.

[0061] In the emergency operation mode, the gravity energy storage device may operate in the energy storage mode, the static mode and the energy release mode before the energy release mode is started. The response time of the three modes increases, that is, the longest response time is the time for switching from the energy storage mode to the energy release mode. Therefore, the support time of the flywheel energy storage device should match the mode switching time of the gravity energy storage device.

[0062] Specifically, Figure 3 Schematic diagram of energy release and response time of MMC, flywheel energy storage device and gravity energy storage device. Figure 3 In the figure, the red curve represents the energy release curve of MMC, the blue curve represents the energy release curve of flywheel energy storage device, the black curve represents the energy release curve of gravity energy storage device, and the green dotted lines represent the response time of MMC, flywheel energy storage device and gravity energy storage device respectively. The horizontal axis is time and the vertical axis is power.

[0063] like Figure 3As shown in the figure, when the emergency operation mode is running (i.e., when the power grid sends an emergency instruction), power commands are simultaneously issued to the gravity energy storage device, the flywheel energy storage device, and the MMC at time t0. The MMC has the fastest response speed and responds to the power command at time t1, delivering active power to the power grid. At time t2, the flywheel energy storage device responds to the power command and sends out active power to the power grid. At time t3, the capacitors in the MMC sub-module are depleted of energy, but at this time, the flywheel energy storage device has been started to maintain the DC bus voltage, and the gravity-flywheel-converter hybrid energy storage system continues to deliver active power to the power grid. At time t4, the gravity energy storage device starts and responds to the power command, jointly maintaining the DC bus voltage with the flywheel energy storage device and delivering active power to the power grid through the MMC. At time t5, the flywheel energy storage device completes discharging. At this time, the gravity energy storage system device completes ramping and undertakes the task of continuously delivering power to the power grid until there is a power surplus in the power grid. After charging the flywheel energy storage device and the gravity energy storage device, the system enters the standby mode. Therefore, t0~t1 is the response duration of the MMC, t0~t2 is the response duration of the flywheel energy storage device, t0~t4 is the response duration of the gravity energy storage device, t1~t3 is the discharging duration of the MMC, t2~t5 is the discharging duration of the flywheel energy storage device, and after t4 is the discharging duration of the gravity energy storage device.

[0064] Specifically, to ensure that the gravity-flywheel-converter hybrid energy storage system can continuously and steadily support the power grid in case of emergencies, as Figure 3 shown, it should be ensured that: t2 < t3, that is, the response duration of the MMC + the discharging duration of the MMC > the response duration of the flywheel energy storage device; t4 < t5, that is, the response duration of the flywheel energy storage device + the discharging duration of the flywheel energy storage device > the response duration of the gravity energy storage device.

[0065] According to some further exemplary embodiments of the present application, controlling the discharge of the capacitors in the power electronic commutation device, the discharge of the flywheel energy storage device, and the discharge of the gravity energy storage device includes: controlling the capacitors in the power electronic commutation device to start discharging; determining whether the output power of the power electronic commutation device begins to decrease; when the output power of the power electronic commutation device begins to decrease, controlling the flywheel energy storage device to start discharging; determining whether the sum of the output powers of the flywheel energy storage device and the power electronic commutation device begins to decrease; when the sum of the output powers of the flywheel energy storage device and the power electronic commutation device begins to decrease, controlling the gravity energy storage device to start discharging, so that a curve of the total output power of the gravity-flywheel-commutation device ternary hybrid energy storage system is a monotonically increasing function, wherein the total output power is the sum of the output power of the power electronic commutation device, the output power of the flywheel energy storage device, and the output power of the gravity energy storage device. In this embodiment, the control strategy is used to ensure that the total output power curve of the gravity-flywheel-commutation device ternary hybrid energy storage system in an emergency situation presents a monotonically increasing trend from the beginning to the end, thereby ensuring that stable power can be provided to the power grid, effectively reducing the sudden change of the grid voltage, and further enhancing the stability and reliability of the gravity-flywheel-commutation device ternary hybrid energy storage system.

[0066] Specifically, if Figure 4 As shown in FIG, in order to ensure that the gravity-flywheel-commutation device ternary hybrid energy storage system can provide stable power to the grid in an emergency, it should also be ensured that the total output power curve of the gravity-flywheel-commutation device ternary hybrid energy storage system (i.e., the sum of the output power of the MMC, the output power of the flywheel energy storage device, and the output power of the gravity energy storage device) is a monotonically increasing function. Figure 4 In the figure, the red curve represents the output power curve of MMC, the blue curve represents the output power curve of flywheel energy storage device, and the black curve represents the output power curve of gravity energy storage device. The horizontal axis is time and the vertical axis is power. The meaning of each moment from t0 to t5 is the same as Figure 4 Same as in.

[0067] It should be noted that the power in this application refers to active power.

[0068] In other embodiments, the master controller is configured to send a first control instruction to the gravity energy storage controller upon receiving a fault prediction instruction from the power grid. The fault prediction instruction indicates an impending power grid failure. In this embodiment, when an impending power grid failure is predicted, the first control instruction is first sent to the gravity energy storage controller. Since the gravity energy storage device has the longest response time, the gravity energy storage device can be put into energy release mode in advance so that it can subsequently transmit power to the power grid in a timely manner.

[0069] Specifically, the controller of the power grid itself can obtain the current load data, current operating status data and current meteorological data of the power grid; input the current load data, current operating status data and current meteorological data into the neural network model, so that the neural network model analyzes the current load data, current operating status data and current meteorological data, and outputs a prediction result. The machine learning model is trained by neural network learning using multiple sets of data, and each set of data in the multiple sets of data includes: historical load data, historical operating status data, historical meteorological data and historical fault results; when the prediction result indicates that the probability of the power grid failing is greater than a preset probability threshold, the controller of the power grid itself sends a fault prediction instruction to the main controller.

[0070] In other embodiments, the flywheel energy storage controller is used to control the flywheel energy storage drive structure to drive the rotation of the rotor structure to decelerate according to a preset deceleration rule when receiving a third control instruction, wherein, in the preset deceleration rule, the deceleration rate increases over time; the gravity energy storage controller is used to control the gravity energy storage drive structure to drive the energy storage object to perform a downward movement according to a preset downward rule when receiving a first control instruction, wherein, in the preset downward rule, the downward speed increases over time. In this embodiment, it can be ensured that the flywheel energy storage drive structure and the gravity energy storage drive structure can provide a large amount of power support in a short time, and the problem of the flywheel energy storage device and the gravity energy storage device outputting less and less power over time is reduced.

[0071] In other embodiments, the gravity-flywheel-commutation device ternary hybrid energy storage system further includes an AC busbar for connecting the power grid to the gravity energy storage device, the power grid to the flywheel energy storage device, and the power grid to the power electronic commutation device. In this embodiment, the presence of the AC busbar allows each device to operate independently or collaboratively, thereby increasing the overall flexibility of the system.

[0072] Specifically, for better versatility, such as Figure 5 As shown, for special cases such as the voltage of the gravity energy storage device 101 and the flywheel energy storage device 103 not matching the voltage of the power electronic commutation device 104, the gravity energy storage device 101 and the flywheel energy storage device 103 collect energy from the power electronic commutation device 104 through the AC bus 106. One end of the power electronic commutation device 104 is used to connect to the power grid 102 through the AC bus 106, and the other end of the power electronic commutation device 104 is used to connect to the wind and solar station 107. The power electronic commutation device 104 obtains electric energy from the wind and solar station 107, thereby discharging to the power grid 102, that is, the power electronic commutation device 104 effectively connects and transmits the electric energy generated by the wind and solar station 107 to the power grid 102. The power electronic commutation device 104 supports large-scale wind and solar stations 107 to generate electricity and connect to the grid.

[0073] Furthermore, gravity energy storage equipment can be connected to the grid using a power electronic converter interface, a synchronous motor interface, etc.; flywheel energy storage equipment can also be a synchronous motor interface and a power electronic converter interface, and its flywheel shaft system can be a traditional mechanical shaft system or a shaft system with added magnetic gears, etc.

[0074] In summary, the gravity-flywheel-commutation device ternary hybrid energy storage system of the present application utilizes capacitors in power electronic commutation equipment to store energy, and can obtain an energy storage effect with an extremely short response time without adding additional energy storage equipment; it covers energy storage technologies with energy storage response times from ms to minutes, realizing the response of energy storage systems at multiple time scales; it covers energy storage technologies with energy storage times from seconds to hours, and can provide fast response, large capacity, and long-term energy support functions.

[0075] An embodiment of the present application also provides a smart grid, comprising: any one of the above-mentioned gravity-flywheel-commutation device ternary hybrid energy storage systems.

[0076] Obviously, those skilled in the art will appreciate that the various modules or steps of the present invention described above can be implemented using a general-purpose computing device, can be centralized on a single computing device, or can be distributed across a network of multiple computing devices. They can be implemented using program code executable by the computing device, and thus, can be stored in a storage device and executed by the computing device. In some cases, the steps shown or described herein can be performed in a different order than that shown, or can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0077] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0078] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0079] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0080] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0081] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0082] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0083] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can be implemented using any method or technology for information storage. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change RAM (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media, such as modulated data signals and carrier waves.

[0084] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0086] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0087] In the gravity-flywheel-commutation device ternary hybrid energy storage system of the present application, the gravity-flywheel-commutation device ternary hybrid energy storage system includes a gravity energy storage device, a flywheel energy storage device and a power electronic commutation device for being electrically connected to the power grid, and also includes a main controller that is communicatively connected to the gravity energy storage device, the flywheel energy storage device, the power electronic commutation device and the power grid respectively. The main controller is used to control the discharge of the capacitor in the power electronic commutation device, the discharge of the flywheel energy storage device and the discharge of the gravity energy storage device when receiving an emergency instruction sent by the power grid, so as to transmit electric energy to the power grid, wherein the start time of the discharge of the flywheel energy storage device is before the end time of the discharge of the power electronic commutation device, and the start time of the discharge of the gravity energy storage device is before the end time of the discharge of the flywheel energy storage device. Compared with the problem in the prior art that a single energy storage technology cannot meet the continuous power support requirements of the new power system on multiple time scales, in this application, when the main controller receives the emergency command sent by the power grid, the capacitor in the power electronic commutation device can respond quickly and start discharging, providing instantaneous power support. This is the fastest first-level response to the power grid, ensuring the system's immediate response to grid emergencies; the flywheel energy storage device starts discharging before the power electronic commutation device finishes discharging, and can seamlessly connect after the short power support provided by the power electronic commutation device, extending the power output time to support at the second to minute level; the gravity energy storage device serves as the third-level storage Energy resources, the response time is relatively long, but it starts discharging before the flywheel energy storage device is fully discharged, and can provide hourly level power support for the power grid, which is an effective support for large-scale energy demand and the key to solving long-term power shortages; the gravity-flywheel-commutation equipment ternary hybrid energy storage system of the present application can form multi-level and multi-time scale power support through the fast-starting capacitor, the subsequent flywheel energy storage and the subsequent gravity energy storage when the power grid encounters an emergency, effectively alleviating the power shortage during the power grid failure, enhancing the resilience and stability of the power grid, not only improving the rapid response capability to power grid failures, but also maintaining stable power output for a long time.

[0088] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A gravity-flywheel-commutation device ternary hybrid energy storage system, characterized in that: The gravity-flywheel-commutation device ternary hybrid energy storage system includes: Gravity energy storage equipment for electrical connection to the grid; a flywheel energy storage device for electrical connection to the power grid; A power electronic commutation device, configured to be electrically connected to the power grid, wherein the power electronic commutation device comprises a capacitor; a main controller, communicatively connected to the gravity energy storage device, the flywheel energy storage device, the power electronic commutation device, and the power grid, and configured to control the discharge of the capacitor in the power electronic commutation device, the discharge of the flywheel energy storage device, and the discharge of the gravity energy storage device to transmit electric energy to the power grid upon receiving an emergency instruction from the power grid, wherein the emergency instruction indicates that the power grid has failed and needs to be charged; The start time of discharge of the flywheel energy storage device is before the end time of discharge of the power electronic commutation device, and the start time of discharge of the gravity energy storage device is before the end time of discharge of the flywheel energy storage device.

2. The gravity-flywheel-commutation device ternary hybrid energy storage system according to claim 1, characterized in that: The power electronic commutation device further includes a DC bus, which is used to connect the power grid and the gravity energy storage device, and the power grid and the flywheel energy storage device.

3. The gravity-flywheel-commutation device ternary hybrid energy storage system according to claim 1, characterized in that: The main controller is also used for: Upon receiving a power surplus instruction sent by the power grid, respectively acquiring current energy levels of the flywheel energy storage device, the gravity energy storage device, and the power electronic commutation device, the power surplus instruction indicating that the power grid has a power surplus; When the current energy level of the flywheel energy storage device is less than a preset first energy threshold, controlling the flywheel energy storage device to obtain electrical energy from the power grid to complete energy storage; When the current energy level of the gravity energy storage device is less than a preset second energy threshold, controlling the gravity energy storage device to obtain electrical energy from the power grid to complete energy storage; When the current energy level of the power electronic commutation device is less than a preset third energy threshold, the power electronic commutation device is controlled to obtain electric energy from the power grid to complete energy storage.

4. The gravity-flywheel-commutation device ternary hybrid energy storage system according to claim 1, characterized in that: The gravity energy storage device comprises: Energy storage objects; a gravity energy storage drive structure, mechanically connected to the energy storage object; A gravity energy storage controller is electrically connected to the gravity energy storage drive structure and is in communication with the main controller, and is configured to control the gravity energy storage drive structure to drive the energy storage object to move downward upon receiving a first control instruction or a second control instruction; Among them, the first control instruction is an instruction sent by the main controller when it receives the emergency instruction, and the second control instruction is an instruction sent by the main controller when it receives a power shortage instruction sent by the power grid, and the power shortage instruction represents an instruction indicating that the power grid has a power shortage.

5. The gravity-flywheel-commutation device ternary hybrid energy storage system according to claim 1, characterized in that: The flywheel energy storage device comprises: rotor structure; a flywheel energy storage drive structure, mechanically connected to the rotor structure; a flywheel energy storage controller, electrically connected to the flywheel energy storage drive structure and communicatively connected to the main controller, wherein the flywheel energy storage controller is configured to control the flywheel energy storage drive structure to drive the rotation of the rotor structure to decelerate upon receiving a third control instruction or a fourth control instruction; Among them, the third control instruction is an instruction sent by the main controller when it receives the emergency instruction, and the fourth control instruction is an instruction sent by the main controller when it receives the power shortage instruction sent by the power grid and monitors that the output power of the gravity energy storage device is less than the target power. The power shortage instruction represents an instruction indicating that the power grid has a power shortage, and the target power represents the power that the power grid needs to supplement.

6. The gravity-flywheel-commutation device ternary hybrid energy storage system according to claim 1, characterized in that: The power electronic commutation device further includes: A power electronic controller is electrically connected to the capacitor and is communicatively connected to the main controller. The power electronic controller is used to control the capacitor to discharge when a fifth control instruction is received, wherein the fifth control instruction is an instruction sent by the main controller when the emergency instruction is received.

7. The gravity-flywheel-commutation device ternary hybrid energy storage system according to claim 6, characterized in that: The main controller is also used for: Upon receiving a power shortage instruction sent by the power grid and monitoring that the sum of the output powers of the gravity energy storage device and the flywheel energy storage device is less than the target power, a sixth control instruction is sent to the power electronic controller so that the power electronic controller controls the capacitor to discharge, wherein the power shortage instruction represents an instruction indicating that the power grid has a power shortage, and the target power represents the power that the power grid needs to supplement.

8. The gravity-flywheel-commutation device ternary hybrid energy storage system according to claim 1, characterized in that: Controlling the discharge of the capacitor, the flywheel energy storage device, and the gravity energy storage device in the power electronic commutation device includes: Controlling the capacitor in the power electronic commutation device to start discharging; determining whether the output power of the power electronic commutation device begins to decrease; When the output power of the power electronic commutation device begins to decrease, controlling the flywheel energy storage device to start discharging; determining whether the sum of the output powers of the flywheel energy storage device and the power electronic commutation device begins to decrease; When the sum of the output powers of the flywheel energy storage device and the power electronic commutation device begins to decrease, the gravity energy storage device is controlled to start discharging so that the curve of the total output power of the gravity-flywheel-commutation device ternary hybrid energy storage system is a monotonically increasing function, wherein the total output power is the sum of the output power of the power electronic commutation device, the output power of the flywheel energy storage device and the output power of the gravity energy storage device.

9. The gravity-flywheel-commutation device ternary hybrid energy storage system according to claim 1, characterized in that: The gravity-flywheel-commutation device ternary hybrid energy storage system further includes: The AC bus is used to connect the power grid and the gravity energy storage device, the power grid and the flywheel energy storage device, and the power grid and the power electronic commutation device.

10. A smart grid, characterized in that: include: The gravity-flywheel-commutation device ternary hybrid energy storage system according to any one of claims 1 to 9.

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