Flywheel energy storage system and control method

Abstract

The invention provides a flywheel energy storage system and a control method, and relates to the technical field of new energy storage. The flywheel energy storage system comprises at least one flywheel device, and each flywheel device comprises a motor and a flywheel body; the flywheel array converter is connected with each flywheel device and comprises a direct current bus; a first port of each machine side rectification unit is connected with the corresponding flywheel device, and a second port of each machine side rectification unit is connected with the direct current bus; a DC brake unit; a first port of the interface unit is connected with the direct current bus, and a second port of the interface unit is connected with an external energy system; and the flywheel control device is respectively connected with the flywheel array converter and the at least one flywheel device, and is used for monitoring operation information of the flywheel energy storage system and controlling the flywheel energy storage system to meet inertia response, primary frequency modulation and secondary frequency modulation requirements of the alternating current power grid.

Description

Technical Field

[0001] The present disclosure relates to the field of new energy storage technology, and in particular to a flywheel energy storage system and a control method. Background Art

[0002] Flywheel energy storage is an advanced physical energy storage technology originated from aerospace. It refers to the use of electrical energy to drive the flywheel to rotate at high speed, converting electrical energy into mechanical energy. It can also use the flywheel inertia to drag the motor to generate electricity, and convert the stored mechanical energy into electrical energy output. Different from other energy storage technologies, its superiority is reflected in the short-time, high-frequency, and high-power charging and discharging characteristics. It is mainly used in the fields of power grid frequency regulation, new energy power station grid connection, rail transportation, and high-power uninterruptible power supply.

[0003] When traditional flywheel energy storage systems are used for grid connection, due to the limited energy and power of a single flywheel, multiple single flywheels are usually used to form an array and run in parallel. However, traditional flywheel energy storage systems can only control the flywheel energy storage, and cannot coordinate other energy sources for grid connection scheduling and control, making it difficult to meet the needs of grid inertia response, primary frequency regulation, and secondary frequency regulation. Summary of the invention

[0004] The present disclosure provides a flywheel energy storage system and a control method.

[0005] According to a first aspect of the present disclosure, a flywheel energy storage system is provided, comprising:

[0006] At least one flywheel device, each flywheel device includes a motor and a flywheel body;

[0007] A flywheel array converter connected to each flywheel device includes:

[0008] DC bus;

[0009] At least one machine-side rectifier unit, each machine-side rectifier unit corresponds to a flywheel device, a first port of each machine-side rectifier unit is connected to the corresponding flywheel device, a second port of each machine-side rectifier unit is connected to a DC bus, and each machine-side rectifier unit is used for conversion between AC and DC;

[0010] A DC braking unit is connected to the DC bus and is used to discharge the energy of the DC bus;

[0011] An interface unit, wherein a first port of the interface unit is connected to the DC bus, and a second port of the interface unit is connected to an external energy system;

[0012] The flywheel control device is respectively connected to the flywheel array converter and at least one flywheel device, and is used to monitor the operation information of the flywheel energy storage system and control the flywheel energy storage system to meet the inertia response, primary frequency regulation and secondary frequency regulation requirements of the AC power grid.

[0013] According to a second aspect of the present disclosure, there is provided a control method for the flywheel energy storage system of the first aspect, comprising:

[0014] Obtain frequency-related information of the AC power grid;

[0015] Determine frequency change information of the AC power grid based on frequency related information;

[0016] A control strategy corresponding to the frequency change information is adopted to control the flywheel energy storage system and / or the external energy system to perform energy scheduling operations.

[0017] According to a third aspect of the present disclosure, there is provided a control device for the flywheel energy storage system of the first aspect, comprising:

[0018] The acquisition module is used to obtain frequency related information of the AC power grid.

[0019] The calculation module is used to determine the frequency change information of the AC power grid according to the frequency related information.

[0020] The control module is used to adopt a control strategy corresponding to the frequency change information to control the flywheel energy storage system and / or the external energy system to perform energy scheduling operations.

[0021] According to the technology disclosed in the present invention, by configuring multiple energy storage interfaces to access an external energy system and communicating with the external energy system through a flywheel control device, grid-connected scheduling and coordinated control of the flywheel device and other external energy systems can be achieved, solving the problem that traditional flywheel energy storage systems are difficult to achieve grid inertia response, primary frequency regulation and secondary frequency regulation requirements.

[0022] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to better understand the present solution and do not constitute a limitation on the present disclosure.

[0024] Figure 1 It is a structural block diagram of a flywheel energy storage system provided according to an embodiment of the present disclosure.

[0025] Figure 2 It is a structural block diagram of another flywheel energy storage system provided according to an embodiment of the present disclosure.

[0026] Figure 3 It is a flow chart of a control method of a flywheel energy storage system provided according to an embodiment of the present disclosure.

[0027] Figure 4 It is a structural block diagram of a control device of a flywheel energy storage system provided according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0028] The following is a description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, which includes various details of the embodiments of the present disclosure to facilitate understanding, and they should be considered as merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for the sake of clarity and conciseness, the description of well-known functions and structures is omitted in the following description. Among them, in the description of the present disclosure, unless otherwise specified, " / " means or, for example, A / B can mean A or B; "and / or" in this article is only a description of the association relationship of associated objects, indicating that three relationships can exist, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone.

[0029] The flywheel energy storage system is an advanced physical energy storage system originated from aerospace. It uses electric energy to drive the flywheel to rotate at high speed, converting electric energy into mechanical energy. It can also use the flywheel inertia to drive the motor to generate electricity, converting the stored mechanical energy into electric energy output. Different from other energy storage technologies, its superiority is reflected in the short-time, high-frequency, and high-power charging and discharging characteristics. It is mainly used in the fields of power grid frequency regulation, new energy power station grid connection, rail transportation, and high-power uninterruptible power supply.

[0030] When traditional flywheel energy storage systems are used for grid connection, due to the limited energy and power of a single flywheel, multiple single flywheels are usually used to form an array and run in parallel. Traditional flywheel energy storage systems can only control the flywheel energy storage, but cannot coordinate other energy sources for grid connection scheduling and control, making it difficult to meet the needs of grid inertia response, primary frequency regulation, and secondary frequency regulation.

[0031] To this end, the present disclosure provides a flywheel energy storage system and a control method. Specifically, the flywheel energy storage system and the control method of the embodiments of the present disclosure are described below with reference to the accompanying drawings.

[0032] Figure 1 This is a structural block diagram of a flywheel energy storage system provided according to an embodiment of the present disclosure. The flywheel energy storage system may include at least one flywheel device, a flywheel array converter connected to each flywheel device, and a flywheel control device. The flywheel device may include but is not limited to a flywheel and a motor. The flywheel array converter may include a DC bus, at least one machine-side rectifier unit, a DC brake unit, an interface unit, and a flywheel control device. Figure 1 The number and form of devices shown are for illustrative purposes only and do not constitute a limitation on the embodiments of the present disclosure. Figure 1The number of flywheel devices in the flywheel energy storage system shown is shown as two for example. Figure 1 As shown, the flywheel energy storage system in the embodiment of the present application includes a first flywheel device 100, a second flywheel device 200, a flywheel array converter 300 and a flywheel control device 400. Among them, the first flywheel device 100 includes a motor 102 and a flywheel 101, the second flywheel device 200 includes a motor 202 and a flywheel 201, and the flywheel array converter 300 includes a DC bus 301, a first machine-side rectifier unit 302, a second machine-side rectifier unit 303, a DC brake unit 304, and an interface unit 305.

[0033] In some embodiments of the present disclosure, the flywheel array converter 300 is connected to each flywheel device, that is, the flywheel array converter is connected to the first flywheel device 100 and the second flywheel device 200 respectively. Each machine-side rectifier unit in the flywheel array converter 300 corresponds to a flywheel device, the first port of each machine-side rectifier unit is connected to the corresponding flywheel device, the second port of each machine-side rectifier unit is connected to the DC bus, and each machine-side rectifier unit is used for conversion between AC and DC. Figure 1 As shown, the first port of the first machine-side rectifier unit 302 in the flywheel array converter 300 is connected to the first flywheel device 100, and the second port of the first machine-side rectifier unit 302 is connected to the DC bus 301. The first port of the second machine-side rectifier unit 303 in the flywheel array converter 300 is connected to the second flywheel device 200, and the second port of the second machine-side rectifier unit 303 is connected to the DC bus 301.

[0034] In some embodiments of the present disclosure, the flywheel control device 400 is respectively connected to the first flywheel device 100, the second flywheel device 200, the flywheel array inverter 300 and the external energy system, and is used to monitor the operating information of the flywheel energy storage system and control the flywheel energy storage system to meet the inertia response, primary frequency regulation and secondary frequency regulation requirements of the AC power grid.

[0035] like Figure 1 As shown, the first flywheel device 100 and the second flywheel device 200 are respectively connected in parallel to the DC bus 301 of the flywheel array converter 300 through the first machine-side rectifier unit 302 and the second machine-side rectifier unit 303. The motor 102 in the first flywheel device 100 and / or the motor 202 in the second flywheel device 200 can work in a generator state or a motor state.

[0036] As a possible implementation method, when the motor 102 in the first flywheel device 100 and / or the motor 202 in the second flywheel device 200 operates in a generator state, the first machine-side rectifier unit 302 and / or the second machine-side rectifier unit 303 rectifies the AC current generated by the motor 102 and the motor 202 into a DC current of the DC bus 301 in the flywheel array converter 300.

[0037] As another possible implementation, when the motor 102 in the first flywheel device 100 and / or the motor 202 in the second flywheel device 200 are operating in the motor state, the first machine-side rectifier unit 302 and / or the second machine-side rectifier unit 303 rectifies the DC current of the DC bus 301 in the flywheel array converter 300 into the AC current required for the operation of the motor 102 and the motor 202.

[0038] It should be noted that the motor 102 in the first flywheel device 100 and the motor 202 in the second flywheel device 200 include but are not limited to wound-rotor asynchronous motors, squirrel-cage asynchronous motors, doubly-fed asynchronous motors, permanent magnet synchronous motors, electrically excited synchronous motors, etc.

[0039] In some embodiments of the present disclosure, the DC braking unit 304 of the flywheel array converter 300 is connected to the DC bus 301, and the DC braking unit 304 can be used for energy discharge of the DC bus 301. The DC braking unit 304 includes a switch and an energy discharge resistor, and a disconnectable fuse or switch protection device can also be set at the first port connected to the DC bus 301.

[0040] In some embodiments of the present disclosure, a first port of the interface unit 305 of the flywheel array converter 300 is connected to the DC bus 301, and a second port of the interface unit 305 is connected to an external energy system.

[0041] As a possible implementation, the interface unit 305 of the flywheel array converter 300 includes a DC conversion interface unit, the first port of which is connected to the DC bus 301 of the flywheel array converter 300, and the second port is connected to the DC bus in the external energy system. The flywheel energy storage system is connected to the AC power grid through the grid-side inverter unit in the external energy system. Among them, the DC conversion interface unit can realize the conversion of the voltage of the DC bus 301 of the flywheel array converter 300 and the voltage of the DC bus of the external energy system, and the first port and the second port of the DC conversion interface unit are respectively provided with a disconnectable fuse or switch protection device.

[0042] Optionally, in some embodiments of the present disclosure, the external energy system includes an energy unit, a DC bus and a grid-side inverter unit, and the energy unit can be a DC energy unit or an AC energy unit. When the energy unit of the external energy system is an AC energy unit, the external energy system also includes a machine-side rectifier unit for converting AC power into DC power.

[0043] It should be noted that the energy units of the external energy system may also include both DC energy units and AC energy units. Among them, the DC energy unit may be a power generation system with DC output, such as: photovoltaic power generation, energy storage battery, wind turbine generator set or load system with DC input characteristics. The AC energy unit may be a power generation system with AC output, such as: compressed air energy storage, diesel generator, gas turbine set or load system with AC input properties.

[0044] As another possible implementation, the interface unit 305 of the flywheel array converter 300 includes a DC conversion interface unit and an AC / DC conversion interface unit. The first port of the AC / DC conversion interface unit is connected to the DC bus 301 of the flywheel array converter 300, and the second port is connected to the external energy system. The external energy system is incorporated into the flywheel energy storage system through the AC / DC conversion interface unit, and the energy unit of the external energy system may include an AC energy unit. The AC / DC conversion interface unit can realize the conversion between the voltage of the DC bus 301 of the flywheel array converter 300 and the voltage of the external energy system, and the first port and the second port of the AC / DC conversion interface unit are respectively provided with a fuse or a switch protection device.

[0045] Optionally, in some embodiments of the present disclosure, the number of DC conversion interface units and AC / DC conversion interface units can be adjusted according to the number requirement of external energy systems, that is, the number of DC conversion interface units or AC / DC conversion interface units connected in parallel on the DC bus 301 of the flywheel array inverter 300 can be increased or decreased, so as to achieve flexible configuration of multiple external energy systems connected to the flywheel energy storage system.

[0046] In the embodiments of the present disclosure, the flywheel energy storage system can be connected to other external energy systems through an interface unit, and connected to the AC power grid through the external energy system. The flywheel device and other external energy systems can also be uniformly coordinated, controlled and monitored through a flywheel control device, thereby improving the flexibility of active power scheduling of the power grid.

[0047] Figure 2 is a structural block diagram of another flywheel energy storage system provided according to an embodiment of the present disclosure. Figure 2 As shown, the flywheel energy storage system also includes a grid-side inverter unit 306 as an example.

[0048] like Figure 2 As shown, the flywheel array converter 300 further includes a grid-side inverter unit 306. The first port of the grid-side inverter unit 306 is connected to the DC bus 301 of the flywheel array converter 300, and the second port is connected to the AC grid, for connecting the flywheel energy storage system to the AC grid.

[0049] As a possible implementation, the interface unit 305 includes: a DC conversion interface unit and / or an AC / DC conversion interface unit. The DC conversion interface unit and / or the AC / DC conversion interface unit are connected in parallel to the DC bus 301 of the flywheel array converter 300. Among them, the second port of the DC conversion interface unit is connected to the external energy system, and the DC conversion interface unit can realize the conversion of the DC voltage of the DC bus 301 of the flywheel array converter 300 with the DC voltage of the external energy system, and the first port and the second port of the DC conversion interface unit are respectively provided with a fuse or a switch protection device. The external energy system is incorporated into the flywheel energy storage system through the DC conversion interface unit, and the energy unit of the external energy system may include a DC energy unit. Among them, the second port of the AC / DC conversion interface unit is connected to the external energy system, and the AC / DC conversion interface unit can realize the conversion of the DC voltage of the DC bus 301 of the flywheel array converter 300 with the AC voltage of the external energy system, and the first port and the second port of the AC / DC conversion interface unit are respectively provided with a fuse or a switch protection device. The external energy system is incorporated into the flywheel energy storage system through an AC / DC conversion interface unit, and the energy unit of the external energy system may include an AC energy unit.

[0050] In some embodiments of the present disclosure, the interface unit 305 of the flywheel array converter 300 includes a DC conversion interface unit, a first port of which is connected to the DC bus 301 of the flywheel array converter 300, and a second port of which is connected to an external energy system having a DC energy unit.

[0051] In the embodiments of the present disclosure, configuring a grid-side inverter unit in the flywheel array converter can directly connect the flywheel energy storage system to the AC power grid, thereby improving the speed at which the flywheel control system acquires power grid operating status information, and thereby improving the response speed of the flywheel energy storage system to instructions such as power grid inertia response, primary frequency regulation, and secondary frequency regulation.

[0052] Figure 3 It is a flow chart of a control method of a flywheel energy storage system provided according to an embodiment of the present disclosure. It should be noted that the control method of a flywheel energy storage system of an embodiment of the present disclosure is used for the flywheel energy storage system in the above embodiment, and the method can also be applied to a control device of a flywheel energy storage system of an embodiment of the present disclosure. Figure 3 As shown, the control method of the flywheel energy storage system includes the following steps:

[0053] S301: Acquire frequency-related information of the AC power grid.

[0054] S302: Determine frequency change information of the AC power grid according to frequency-related information.

[0055] S303: adopting a control strategy corresponding to the frequency change information to control the flywheel energy storage system and / or the external energy system to perform energy scheduling operations.

[0056] In some embodiments of the present disclosure, the control strategies corresponding to the frequency change information include inertia response, primary frequency regulation, secondary frequency regulation and other control strategies that meet the grid dispatching requirements.

[0057] As a possible implementation manner, the frequency-related information of the AC power grid that needs to be obtained includes: an initial frequency value and a final frequency value of the AC power grid within a first time interval, and a first acceptable frequency change dead zone of the AC power grid.

[0058] It should be noted that the first time interval is a time period length preset in advance; the initial value of the frequency of the AC power grid in the first time interval is the operating frequency of the AC power grid at the start time of the first time interval; the final value of the frequency of the AC power grid in the first time interval is the operating frequency of the AC power grid at the end time of the first time interval. For example, if the first time interval is set to 20s, the initial value of the frequency in the first time interval refers to the frequency of the AC power grid monitored in real time at the 1st second of the first time interval, and the final value of the frequency in the first time interval refers to the frequency of the AC power grid monitored in real time at the 20th second of the first time interval.

[0059] It should be noted that the first acceptable frequency variation dead zone of the AC power grid can be a set dead zone value within the range of ±0.03Hz / s-0.1Hz / s. For example, the AC power grid is set to a dead zone value of 0.05Hz / s, that is, the range of the first acceptable frequency variation dead zone of the AC power grid is ±0.05Hz / s. When the frequency variation of the AC power grid exceeds the first acceptable frequency variation dead zone, the flywheel control device controls the flywheel energy storage system and / or the external energy system to perform energy scheduling operations.

[0060] In some embodiments of the present disclosure, a specific implementation method for determining the frequency change information of the AC power grid according to the frequency-related information is to calculate the frequency change rate within the first time interval according to the initial frequency value and the final frequency value.

[0061] In some embodiments of the present disclosure, the specific implementation method of calculating the frequency change rate in the first time interval according to the initial frequency value and the final frequency value is to obtain the frequency deviation in the first time interval by subtracting the initial frequency value from the final frequency value, and then calculate the frequency change rate in the first time interval based on the frequency deviation in the first time interval and the duration of the first time interval. The calculation formula of the frequency change rate in the first time interval can be shown as the following formula (1):

[0062]

[0063] Wherein, V represents the frequency change rate in the first time interval, Δf represents the frequency deviation in the first time interval, and ΔT represents the duration of the first time interval. For example, if the first time interval is 20s, the initial value of the frequency in the first time interval is 50Hz, and the final value of the frequency in the first time interval is 49Hz, then the frequency change rate in the first time interval is -0.05Hz / s.

[0064] In some embodiments of the present disclosure, when an inertia response control strategy is adopted, a specific implementation method of controlling the flywheel energy storage system and / or the external energy system to perform energy scheduling operations is to control the flywheel energy storage system and / or the external energy system to perform energy scheduling operations according to the frequency change rate and the first acceptable frequency change dead zone.

[0065] For example, when the frequency change rate is negative and exceeds the first acceptable frequency change dead zone, the flywheel energy storage system and / or the external energy system are controlled to output active power until the frequency change rate returns to the first acceptable frequency change dead zone. When the frequency conversion rate is positive and exceeds the first acceptable frequency change dead zone, the flywheel energy storage system and / or the external energy system are controlled to consume active power until the frequency change dead zone returns to the first acceptable frequency change dead zone.

[0066] As another possible implementation, the frequency-related information of the AC power grid that needs to be obtained includes: the current operating frequency of the AC power grid, the target frequency and the first acceptable frequency dead zone of the AC power grid, wherein the target frequency includes: a preset target frequency or a secondary frequency regulation target frequency.

[0067] It should be noted that the first acceptable frequency dead zone of the AC power grid can be a set dead zone value within the range of ±0.03Hz-0.1Hz. For example, the dead zone value set for the AC power grid is 0.05Hz, that is, the range of the first acceptable frequency dead zone of the AC power grid is ±0.05Hz. When the frequency change of the AC power grid exceeds the first acceptable frequency dead zone range of the target frequency of the AC power grid, the flywheel control device controls the flywheel energy storage system and / or the external energy system to perform energy scheduling operations.

[0068] In some embodiments of the present disclosure, the specific implementation method of determining the frequency change information of the AC power grid according to the frequency-related information can also be to calculate the frequency deviation of the AC power grid according to the current operating frequency and the target frequency of the AC power grid. For example, if the current operating frequency of the AC power grid is 49 Hz and the target frequency of the AC power grid is 50 Hz, then the frequency deviation of the AC power grid is 1 Hz.

[0069] In some embodiments of the present disclosure, when a primary frequency regulation or a secondary frequency regulation control strategy is adopted, a specific implementation method of controlling the flywheel energy storage system and / or the external energy system to perform energy scheduling operations is to control the flywheel energy storage system and / or the external energy system to perform energy scheduling operations according to the frequency deviation and the first acceptable frequency dead zone.

[0070] For example, when the frequency deviation is negative and exceeds the first acceptable frequency dead zone, the flywheel energy storage system and / or the external energy system are controlled to output active power until the frequency deviation returns to the first acceptable frequency dead zone; when the frequency deviation is positive and exceeds the first acceptable frequency dead zone, the flywheel energy storage system and / or the external energy system are controlled to consume active power until the frequency deviation returns to the first acceptable frequency dead zone.

[0071] It should be noted that the target frequency of the AC power grid in the primary frequency regulation control strategy is a preset target frequency. The target frequency of the AC power grid in the secondary frequency regulation control strategy is the secondary frequency regulation target frequency, that is, the target frequency set by the power grid management agency.

[0072] It should be noted that, because the flywheel device has the characteristics of short-time, high-frequency, and high-power charging and discharging, the flywheel device with fast inertia support capability will output or consume active power first when the flywheel energy storage system performs energy scheduling operations. After the energy of the flywheel device is exhausted or full, other external energy systems will be controlled to output or consume active power.

[0073] In an embodiment of the present disclosure, a control method for a flywheel energy storage system can obtain information related to the grid frequency, thereby determining grid frequency change information, and adopt corresponding control strategies based on the grid frequency change information to execute corresponding energy scheduling operations to meet the inertia response, primary frequency regulation, and secondary frequency regulation requirements of the AC grid.

[0074] Figure 4 is a structural block diagram of a control device for a flywheel energy storage system provided according to an embodiment of the present disclosure. Figure 4 As shown, the control device of the flywheel energy storage system includes an acquisition module 401 , a calculation module 402 , and a control module 403 .

[0075] The acquisition module 401 is used to acquire frequency-related information of the AC power grid.

[0076] The calculation module 402 is used to determine the frequency change information of the AC power grid according to the frequency related information.

[0077] The control module 403 is used to adopt a control strategy corresponding to the frequency change information to control the flywheel energy storage system and / or the external energy system to perform energy scheduling operations.

[0078] In some embodiments of the present disclosure, the acquisition module 401 is specifically used to obtain the initial frequency value, the final frequency value and the first acceptable frequency change dead zone of the AC power grid within the first time interval; obtain the current operating frequency, the target frequency and the first acceptable frequency dead zone of the AC power grid.

[0079] In some embodiments of the present disclosure, the calculation module 402 is specifically used to calculate the frequency change rate in the first time interval according to the initial frequency value and the final frequency value; and calculate the frequency deviation of the AC power grid according to the current operating frequency and the target frequency of the AC power grid.

[0080] In some embodiments of the present disclosure, the control module 403 is specifically used to control the flywheel energy storage system and / or the external energy system to perform energy scheduling operations according to the frequency change rate and the first acceptable frequency change dead zone.

[0081] For example, when the frequency change rate is negative and exceeds the first acceptable frequency change dead zone, the flywheel energy storage system and / or the external energy system is controlled to output active power until the frequency change rate returns to the first acceptable frequency change dead zone; when the frequency change rate is positive and exceeds the first acceptable frequency change dead zone, the flywheel energy storage system and / or the external energy system is controlled to consume active power until the frequency change dead zone returns to the first acceptable frequency change dead zone.

[0082] In some embodiments of the present disclosure, the control module 403 may be specifically configured to control the flywheel energy storage system and / or the external energy system to perform energy scheduling operations according to the frequency deviation and the first acceptable frequency dead zone.

[0083] For example, when the frequency deviation is negative and exceeds the first acceptable frequency dead zone, the flywheel energy storage system and / or the external energy system are controlled to output active power until the frequency deviation returns to the first acceptable frequency dead zone; when the frequency deviation is positive and exceeds the first acceptable frequency dead zone, the flywheel energy storage system and / or the external energy system are controlled to consume active power until the frequency deviation returns to the first acceptable frequency dead zone.

[0084] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0085] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved, and this document does not limit this.

[0086] The above specific implementations do not constitute a limitation on the protection scope of the present disclosure. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A flywheel energy storage system, characterized in that: include: At least one flywheel device, each of the flywheel devices comprising a motor and a flywheel body; A flywheel array converter connected to each of the flywheel devices comprises: DC bus; At least one machine-side rectifier unit, each of the machine-side rectifier units corresponds to one of the flywheel devices, a first port of each of the machine-side rectifier units is connected to the corresponding flywheel device, a second port of each of the machine-side rectifier units is connected to the DC bus, and each of the machine-side rectifier units is used for conversion between AC and DC; A DC braking unit, the DC braking unit is connected to the DC bus and is used for discharging energy of the DC bus; An interface unit, wherein a first port of the interface unit is connected to the DC bus, and a second port of the interface unit is connected to an external energy system; The flywheel control device is respectively connected to the flywheel array converter and the at least one flywheel device, and is used to monitor the operation information of the flywheel energy storage system and control the flywheel energy storage system to meet the inertia response, primary frequency regulation and secondary frequency regulation requirements of the AC power grid.

2. The flywheel energy storage system according to claim 1, characterized in that: The interface unit comprises: A DC conversion interface unit; wherein the second port of the DC conversion interface unit is connected to the DC bus in the external energy system, and the flywheel energy storage system is connected to the AC power grid through the grid-side inverter unit in the external energy system.

3. The flywheel energy storage system according to claim 2, characterized in that: The interface unit also includes: An AC / DC conversion interface unit; wherein the second port of the AC / DC conversion interface unit is connected to the external energy system, and the external energy system is incorporated into the flywheel energy storage system through the AC / DC conversion interface unit.

4. The flywheel energy storage system according to claim 1, characterized in that: The flywheel array converter also includes: A grid-side inverter unit, wherein a first port of the grid-side inverter unit is connected to the DC bus, wherein the flywheel energy storage system is connected to the AC power grid through the grid-side inverter unit.

5. The flywheel energy storage system according to claim 4, characterized in that: The interface unit comprises: A DC conversion interface unit; wherein the second port of the DC conversion interface unit is connected to the external energy system, and the external energy system is incorporated into the flywheel energy storage system through the DC conversion interface unit, and / or, An AC / DC conversion interface unit; wherein the second port of the AC / DC conversion interface unit is connected to the external energy system, and the external energy system is incorporated into the flywheel energy storage system through the AC / DC conversion interface unit.

6. A control method for a flywheel energy storage system according to any one of claims 1 to 5, characterized in that: The method comprises: Acquiring frequency-related information of the AC power grid; Determine frequency change information of the AC power grid according to the frequency related information; A control strategy corresponding to the frequency change information is adopted to control the flywheel energy storage system and / or the external energy system to perform energy scheduling operations.

7. The method according to claim 6, characterized in that The acquiring of frequency-related information of the AC power grid includes: Acquire an initial frequency value, a final frequency value, and a first acceptable frequency change dead zone of the AC power grid within a first time interval; Determining the frequency change information of the AC power grid according to the frequency related information includes: Calculating the frequency change rate within the first time interval according to the initial frequency value and the final frequency value; The adopting of a control strategy corresponding to the frequency change information to control the flywheel energy storage system and / or the external energy system to perform energy scheduling operations includes: According to the frequency change rate and the first acceptable frequency change dead zone, the flywheel energy storage system and / or the external energy system are controlled to perform energy scheduling operations.

8. The method according to claim 6, characterized in that The acquiring of frequency-related information of the AC power grid includes: Acquire the current operating frequency, target frequency and a first acceptable frequency dead zone of the AC power grid, wherein the target frequency includes: a preset target frequency or a secondary frequency modulation target frequency; Determining the frequency change information of the AC power grid according to the frequency related information includes: Calculating a frequency deviation of the AC power grid according to the current operating frequency of the AC power grid and the target frequency; The adopting of a control strategy corresponding to the frequency change information to control the flywheel energy storage system and / or the external energy system to perform energy scheduling operations includes: According to the frequency deviation and the first acceptable frequency dead zone, the flywheel energy storage system and / or the external energy system are controlled to perform energy scheduling operations.

9. The method according to claim 7, characterized in that: According to the frequency change rate and the first acceptable frequency change dead zone, controlling the flywheel energy storage system and / or the external energy system to perform energy scheduling operations includes: When the frequency change rate is a negative number and exceeds the first acceptable frequency change dead zone, controlling the flywheel energy storage system and / or the external energy system to output active power until the frequency change rate returns to the first acceptable frequency change dead zone; When the frequency conversion rate is a positive number and exceeds the first acceptable frequency change dead zone, the flywheel energy storage system and / or the external energy system are controlled to consume active power until the frequency change dead zone returns to the first acceptable frequency change dead zone.

10. The method according to claim 8, characterized in that According to the frequency deviation and the first acceptable frequency dead zone, controlling the flywheel energy storage system and / or the external energy system to perform energy scheduling operations includes: When the frequency deviation is a negative number and exceeds the first acceptable frequency dead zone, controlling the flywheel energy storage system and / or the external energy system to output active power until the frequency deviation returns to the first acceptable frequency dead zone; When the frequency deviation is a positive number and exceeds the first acceptable frequency dead zone, the flywheel energy storage system and / or the external energy system are controlled to consume active power until the frequency deviation returns to the first acceptable frequency dead zone.

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