Flywheel energy storage converter and flywheel energy storage system

Abstract

The utility model discloses a flywheel energy storage converter and a flywheel energy storage system, and relates to the technical field of flywheel energy storage, and the flywheel energy storage converter comprises a DC input unit, a pre-charging unit, a main control unit, a power unit and a flywheel motor. The direct-current input unit is sequentially and electrically connected with the pre-charging unit, the power unit and the flywheel motor, the power unit is further in communication connection with the main control unit so as to adjust energy storage conversion of the flywheel motor according to a control signal of the main control unit, and based on this, the power unit is adjusted by adopting a multi-drive control strategy; and a plurality of groups of double-bridge arms are connected in parallel, so that the aim of coexistence of high-power and high-frequency requirements is fulfilled, and the flywheel energy storage converter which can meet the requirements of high power, high frequency and high reliability is constructed.

Description

Technical Field

[0001] The utility model relates to the technical field of flywheel energy storage, in particular to a flywheel energy storage converter and a flywheel energy storage system. Background Art

[0002] Flywheel energy storage technology is a new energy storage method. When the flywheel motor speeds up, it can convert electrical energy into kinetic energy for storage, and when the flywheel motor speeds down, it converts kinetic energy into generator energy for release. However, due to storage density and charge and discharge times, the existing flywheel energy storage technology lacks a flywheel energy storage unit that can stably output high frequency and short-term high power. Utility Model Content

[0003] In view of the above-mentioned deficiencies in the prior art, the utility model provides a flywheel energy storage inverter and a flywheel energy storage system, which adopts a multi-drive control strategy to adjust the power unit, and adopts a plurality of groups of double bridge arms in parallel to achieve the goal of coexistence of high power and high frequency requirements, thereby constructing a flywheel energy storage inverter that can meet high power, high frequency and high reliability.

[0004] In order to achieve the above-mentioned purpose of the invention, the technical solution adopted by the utility model is:

[0005] In a first aspect, the utility model provides a flywheel energy storage converter, comprising: a DC input unit, a pre-charging unit, a main control unit, a power unit and a flywheel motor;

[0006] The DC input unit is electrically connected to the pre-charging unit, the power unit, and the flywheel motor in sequence. The power unit is also communicatively connected to the main control unit to adjust the energy storage conversion of the flywheel motor according to the control signal of the main control unit.

[0007] Further, the power unit includes at least three power modules, the power modules include a main controller and at least two driving sub-modules, and the driving sub-modules are communicatively connected with the main controller;

[0008] Wherein, the driving sub-modules are arranged in parallel.

[0009] Furthermore, the driving submodule includes a driving board and at least two bridge arms, the driving board is connected to the bridge arms respectively, and the bridge arms are arranged in parallel.

[0010] Furthermore, the power unit further includes at least one current sharing reactor, and the current sharing reactor is arranged at the output end of the bridge arm.

[0011] Furthermore, the power module adopts a T-type three-level topology structure.

[0012] Furthermore, the main control unit includes a controller and a sampling module; the sampling module is respectively connected to the controller and the power unit for communication to obtain voltage data of the power unit and transmit the voltage data to the controller; the controller adjusts the power of the flywheel motor through the power unit according to the voltage data.

[0013] Further, the sampling module includes a current sensor, wherein the current sensor is electrically connected to the power unit.

[0014] Furthermore, the DC input unit includes an isolating switch, a fuse and a contactor which are connected in sequence, wherein the contactor is also connected in parallel with the pre-charging unit.

[0015] Furthermore, the pre-charging unit includes a pre-charging resistor and a pre-charging contactor connected in sequence.

[0016] In a second aspect, the present application further provides a flywheel energy storage system, comprising the flywheel energy storage converter as described in any one of the above-mentioned first aspects.

[0017] The utility model has the following beneficial effects:

[0018] A flywheel energy storage converter and a flywheel energy storage system are provided, wherein the flywheel energy storage converter comprises: a DC input unit, a pre-charging unit, a main control unit, a power unit and a flywheel motor; the DC input unit is electrically connected to the pre-charging unit, the power unit and the flywheel motor in sequence, and the power unit is also communicatively connected to the main control unit to adjust the energy storage conversion of the flywheel motor according to the control signal of the main control unit. Based on this, the power unit in the present application adopts a multi-drive control strategy, and achieves the goal of coexistence of high power and high frequency requirements by connecting two groups of double bridge arms in parallel, thereby constructing a flywheel energy storage converter that can meet high power, high frequency and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure of a flywheel energy storage converter provided in an embodiment of the present application;

[0020] Figure 2 This is one of the structural schematic diagrams of the power unit in the embodiment of the present application;

[0021] Figure 3 A schematic diagram of the topological structure of a single-phase power unit in an embodiment of the present application;

[0022] Figure 4 This is one of the schematic diagrams of the topological structure of the power unit in the embodiment of the present application;

[0023] Figure 5 This is the second structural diagram of the power unit in the embodiment of the present application;

[0024] Figure 6 This is the second schematic diagram of the topological structure of the power unit in the embodiment of the present application;

[0025] Figure 7 This is a schematic diagram of the structure of a DC input unit in an embodiment of the present application;

[0026] Figure 8 Schematic diagram of the topological structure of the flywheel energy storage converter in the embodiment of the present application. DETAILED DESCRIPTION

[0027] The specific implementation modes of the utility model are described below to facilitate the understanding of the invention by those skilled in the art. However, it should be clear that the utility model is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the utility model are protected.

[0028] As described in the background technology, flywheel energy storage technology is an emerging energy storage method. Specifically, when the flywheel speeds up, electrical energy is converted into kinetic energy for storage, and when the flywheel speeds down, the kinetic energy drives the generator to generate electricity and is converted into electrical energy for release. The current technical advantages of flywheel energy storage are high energy storage density, the number of charge and discharge times is independent of the charge and discharge depth and the number of charge and discharge times is theoretically infinite, high energy conversion efficiency, high reliability, easy maintenance, low requirements for environmental conditions, and no pollution. However, according to the inventor's research, with the maturity of the industry, the requirements for power and speed in flywheel energy storage are getting higher and higher. Based on the considerations of storage density and charge and discharge times of flywheel energy storage, there is a lack of a flywheel energy storage unit that can stably output high frequency and short-term high power.

[0029] Based on this, the present application provides a flywheel energy storage inverter and a flywheel energy storage system, which adopts a multi-drive control strategy to adjust the power unit, and adopts multiple groups of dual bridge arms in parallel to achieve the goal of high power and high frequency requirements, and constructs a flywheel energy storage inverter that can meet high power, high frequency and high reliability.

[0030] First, see Figure 1 , In an embodiment of the present application, a flywheel energy storage converter is provided, comprising: a DC input unit, a pre-charging unit, a main control unit, a power unit and a flywheel motor;

[0031] The DC input unit is electrically connected to the pre-charging unit, the power unit, and the flywheel motor in sequence. The power unit is also communicatively connected to the main control unit to adjust the energy storage conversion of the flywheel motor according to the control signal of the main control unit.

[0032] In this embodiment, the main circuit of the flywheel energy storage converter includes a DC input unit, a pre-charging unit, a power unit and a flywheel motor connected in sequence. A DC750V DC power supply can be used to power the main circuit, and the DC750V DC power supply powers the main circuit through the DC input unit. When the main circuit is powered on, the power unit is pre-charged through the pre-charging unit. When the pre-charging is completed, the contactor in the DC input unit is closed, and the flywheel energy storage converter enters a ready state to charge and discharge through the flywheel motor. Among them, the power unit is also connected to the main control unit in communication to form a control circuit to adjust the energy storage conversion of the flywheel motor according to the control signal of the main control unit.

[0033] It should be noted that a flywheel energy storage converter provided in an embodiment of the present application refers to a machine-side converter, whose input is DC and cannot be directly connected to the grid. The output side needs to be connected to a flywheel unit to regulate the charge and discharge of the flywheel, and the front stage of the flywheel energy storage converter needs to be connected to the PCS.

[0034] In one possible embodiment, see Figure 2 The power unit includes at least three power modules, the power module includes a main controller and at least two driving sub-modules, the driving sub-modules are communicatively connected with the main controller; wherein the driving sub-modules are arranged in parallel.

[0035] In an achievable embodiment, the power unit adopts a T-type three-level topology. In this embodiment, the power unit may include three power modules, and the power modules may be single-phase power modules. For the topology of the single-phase power modules, please refer to Figure 3 , understandable, please refer to Figure 4 The power unit can be composed of an A-phase power module, a B-phase power module and a C-phase power module connected in parallel.

[0036] In an achievable embodiment, the power module includes a main controller and at least two drive submodules. Since the present application is to construct a flywheel energy storage converter that can meet the requirements of high power, high frequency and high reliability, a high power (e.g. 1MW) single-phase power unit can be selected. In order to take into account the characteristics of high frequency, a drive submodule with a high switching frequency can be selected. In order to maintain the stability and consistency of the drive signal, a structure in which multiple drive submodules are connected in parallel can be adopted. It can be understood that the power module includes a main controller and at least two drive submodules, and the main controller is respectively connected to the drive submodules, wherein each drive submodule is connected in parallel.

[0037] In one possible embodiment, please refer to Figure 5, the driver submodule includes a driver board and at least two bridge arms, wherein the bridge arms are arranged in parallel. It is understandable that when the high-power single-phase unit is 1200V 600A, the switching frequency is set to 8K, and two driver submodules can be used to construct a four-parallel topology structure. It is understandable that the driver board in each driver submodule drives two single-phase bridge arms respectively, thereby constructing a four-parallel topology structure, and the main controller divides the output into two and transmits it to the two driver submodules at the same time, so that the drive signals between the driver submodules remain highly consistent.

[0038] In one possible embodiment, please refer to Figure 6 The power unit also includes at least one current-sharing reactor L, which is arranged at the output end of the bridge arm. When the power unit can be composed of an A-phase power module, a B-phase power module and a C-phase power module in parallel, it includes three current-sharing reactors, and the current-sharing reactor L1, the current-sharing reactor L2 and the current-sharing reactor L3 are respectively arranged at the output ends of the A-phase power module, the B-phase power module and the C-phase power module.

[0039] In this embodiment, in order to ensure that the output current of the two groups of dual-bridge arm parallel structures of the power unit remains consistent, a current-sharing inductor can be designed and configured on the output side of the power unit. The current-sharing inductor can effectively suppress the circulating current between the bridge arms in the power unit, thereby making the output current of each parallel bridge arm in the driving sub-module consistent. If the current-sharing inductor is used for the current-sharing inductor, the output filtering function can also be achieved through the current-sharing inductor.

[0040] In a feasible embodiment, the power unit adopts a T-type three-level topology structure.

[0041] It can be understood that two driving sub-modules are configured in the power unit, each driving sub-module drives two T-type three-level bridge arms connected in parallel, and the driving signal of the driving sub-module is sent by the same main controller and is sent to the two driving sub-modules at the same time. The driving signal can ensure consistency while ignoring the influence of the driving cable length. Based on this, it is guaranteed that the driving power is sufficient, and the consistency and synchronization of the driving signal are also guaranteed, so that the output of the power unit has high reliability.

[0042] In an achievable embodiment, the main control unit includes a controller and a sampling module; the sampling module is respectively connected to the controller and the power unit in communication to obtain voltage data of the power unit and transmit the voltage data to the controller; the controller adjusts the power of the flywheel motor through the power unit according to the voltage data.

[0043] In this embodiment, the controller collects various voltage and current signals through the sampling module as feedback signals of the energy storage system. Given the signal as speed or power, the controller converts and calculates the feedback signal into the current loop, voltage loop, speed loop, power loop and other control loops to achieve precise control of the speed and power of the flywheel motor. This scheme is only used as a certain exemplary explanation. In the embodiment of the present application, the above-mentioned method for adjusting the power of the flywheel motor is not limited. As long as the above-mentioned voltage and current signals can be collected through the sampling module, the signal can be output through the controller, and the power of the flywheel motor can be adjusted through the power unit.

[0044] Among them, the controller can be a host computer in an achievable embodiment, so as to adjust the power unit based on the voltage and current signals of the acquisition system through the host computer display, so as to issue control instructions of the energy storage inverter through the host computer. Furthermore, the host computer can have control modes such as speed mode, DC voltage regulation mode, and power mode.

[0045] It can be understood that by changing the working mode parameters of the flywheel energy storage inverter, the working mode of the power unit can be set to the speed mode. In this mode, the inverter drives the power module to output the voltage, current and frequency signals according to the given speed issued by the master control, and accurately controls the speed of the motor. In this mode, the power unit is in a speed closed-loop state; similarly, the inverter working mode can be set to the power mode. In this mode, the inverter drives the power module to output the voltage, current and frequency signals according to the given power issued by the master control, and accurately controls the output power of the inverter. In this mode, the power unit is in a power closed-loop state, and the power feedback is provided by the DC power calculated by the DC voltage and current sampling of the inverter.

[0046] It can be understood that in the above two modes, the PCS provides DC regulated power supply, and the power unit is responsible for controlling the speed or power; when the power unit is set to DC regulated mode, the DC voltage of the power unit is in a closed-loop control state, and the power command issued by the master control is controlled by the PCS, and the PCS is in a power closed-loop state.

[0047] Further, the sampling module includes a current sensor, wherein the current sensor is electrically connected to the power unit.

[0048] In a feasible embodiment, the main control unit may also include a human-computer interaction interface and an auxiliary power supply module, wherein the human-computer interaction interface can communicate via an RS485 bus to locally control the flywheel energy storage inverter, thereby driving the flywheel to charge and discharge, and monitoring various working conditions of the inverter.

[0049] The auxiliary power supply module miniature circuit breaker, 24V switching power supply, ±15V switching power supply and 5V switching power supply are used to provide control power to the controller and sampling module.

[0050] In one possible embodiment, Figure 7 As shown, the DC input unit includes a disconnect switch, a fuse and a contactor connected in sequence, wherein the contactor is also connected in parallel with the pre-charging unit. In this embodiment, the DC input unit can control the input and disconnection of the front-stage DC power supply, and has the function of protecting the equipment. The contactor pre-charges the capacitor of the power unit in the pre-charging unit and closes after the pre-charging is completed.

[0051] Furthermore, the pre-charging unit includes a pre-charging resistor and a pre-charging contactor connected in sequence.

[0052] In summary, please refer to Figure 8 , where resistor R1 is the pre-charging resistor; KM1 and KM2 are contactors and pre-charging contactors respectively, F1 is a fuse, and QS1 is an isolating switch. Figure 8 As shown, it can be seen that the flywheel energy storage inverter includes: a DC input unit, a pre-charging unit, a main control unit, a power unit and a flywheel motor; the DC input unit is electrically connected to the pre-charging unit, the power unit and the flywheel motor in sequence, and the power unit is also communicatively connected to the main control unit to adjust the energy storage conversion of the flywheel motor according to the control signal of the main control unit. Based on this, the power unit in the present application adopts a multi-drive control strategy, and achieves the goal of coexistence of high power and high frequency requirements by connecting two groups of double bridge arms in parallel, thereby constructing a flywheel energy storage inverter that can meet high power, high frequency and high reliability.

[0053] In a second aspect, the present application also provides a flywheel energy storage system, comprising the flywheel energy storage converter of any one of the above-mentioned first aspects.

[0054] The flywheel energy storage system includes all the technical means and beneficial effects of the flywheel energy storage device in the first aspect mentioned above, that is, it adopts a multi-drive control strategy, and achieves the goal of coexistence of high power and high frequency requirements by connecting two sets of double bridge arms in parallel, thereby constructing a flywheel energy storage inverter that can meet high power, high frequency and high reliability.

[0055] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0056] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations based on the technical revelations disclosed in the present invention without departing from the essence of the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A flywheel energy storage converter, characterized in that: include: DC input unit, pre-charging unit, main control unit, power unit and flywheel motor; The DC input unit is electrically connected to the pre-charging unit, the power unit, and the flywheel motor in sequence. The power unit is also communicatively connected to the main control unit to adjust the energy storage conversion of the flywheel motor according to the control signal of the main control unit.

2. The flywheel energy storage converter according to claim 1, characterized in that: The power unit includes at least three power modules, each of which includes a main controller and at least two driving sub-modules, and the driving sub-modules are communicatively connected to the main controller; Wherein, the driving sub-modules are arranged in parallel.

3. The flywheel energy storage converter according to claim 2, characterized in that: The driving submodule includes a driving board and at least two bridge arms, wherein the driving board is connected to the bridge arms respectively, and the bridge arms are arranged in parallel.

4. The flywheel energy storage converter according to claim 3, characterized in that: The power unit further includes at least one current sharing reactor, and the current sharing reactor is arranged at the output end of the bridge arm.

5. The flywheel energy storage converter according to claim 2, characterized in that: The power module adopts a T-type three-level topology structure.

6. The flywheel energy storage converter according to claim 1, characterized in that: The main control unit includes a controller and a sampling module; the sampling module is respectively connected to the controller and the power unit for communication to obtain voltage data of the power unit and transmit the voltage data to the controller; the controller adjusts the power of the flywheel motor through the power unit according to the voltage data.

7. The flywheel energy storage converter according to claim 6, characterized in that: The sampling module includes a current sensor, wherein the current sensor is electrically connected to the power unit.

8. The flywheel energy storage converter according to claim 1, characterized in that: The DC input unit includes an isolating switch, a fuse and a contactor which are connected in sequence, wherein the contactor is also connected in parallel with the pre-charging unit.

9. The flywheel energy storage converter according to claim 8, characterized in that: The pre-charging unit includes a pre-charging resistor and a pre-charging contactor which are connected in sequence.

10. A flywheel energy storage system, characterized in that: A flywheel energy storage converter comprising any one of claims 1 to 9.

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