A hybrid energy storage converter, a wind power converter and a control method

Abstract

The present application discloses a hybrid energy storage converter, a wind power converter, and a control method, comprising: a power conversion circuit, a switching circuit, and a controller; the first end of the power conversion circuit is used to connect to a DC bus; the second end of the power conversion circuit is connected to the first end of the switching circuit; the second end of the switching circuit is used to connect to an AC energy storage device, and the third end of the switching circuit is used to connect to a DC energy storage device; the controller is used to control the power conversion circuit to operate in a DC-AC mode, control the first end of the switching circuit to connect to the second end of the switching circuit, so that the power conversion circuit is connected to the AC energy storage device; and is also used to control the power conversion circuit to operate in a DC-DC mode, control the first end of the switching circuit to connect to the third end of the switching circuit, so that the power conversion circuit is connected to the DC energy storage device. The hybrid energy storage device realizes both AC and DC energy storage, stabilizes voltage, frequency, and power, and flexibly realizes the bidirectional flow of electric energy.

Description

Technical Field

[0001] The present application relates to the field of new energy technology, and in particular to a hybrid energy storage converter, a wind power converter and a control method. Background Art

[0002] As new energy becomes more and more popular, wind power generation and photovoltaic power generation are being used more and more. Among them, the photovoltaic array of photovoltaic power generation outputs direct current, and the wind turbine generator set outputs alternating current.

[0003] In wind power generation, wind power converters generally use an AC-DC-AC circuit topology. Currently, energy storage devices are generally installed in wind power generation and photovoltaic power generation.

[0004] Coupling energy storage devices with wind power conversion systems can achieve grid frequency regulation, transfer wind power, and improve wind power system integration performance. Currently, mainstream energy storage devices primarily use electrochemical batteries. When used in wind-storage integrated applications, their response speed, power throughput, and lifespan are limited by their performance. This relatively simple energy storage approach fails to fully leverage the advantages of energy storage. Summary of the Invention

[0005] In order to solve the above technical problems, the present application provides a hybrid energy storage converter device, a wind power converter and a control method, which can adopt hybrid energy storage, have a flexible energy storage method, and can better play the advantages of energy storage.

[0006] The present application provides a hybrid energy storage and current conversion device, comprising: a power conversion circuit, a switching circuit, and a controller; a first end of the power conversion circuit is used to connect to a DC bus; a second end of the power conversion circuit is connected to a first end of the switching circuit; a second end of the switching circuit is used to connect to an AC energy storage device, and a third end of the switching circuit is used to connect to a DC energy storage device;

[0007] The controller is used to control the power conversion circuit to operate in a DC-AC mode, control the first end of the switching circuit to be connected to the second end of the switching circuit, so that the power conversion circuit is connected to the AC energy storage device; and is also used to control the power conversion circuit to operate in a DC-DC mode, control the first end of the switching circuit to be connected to the third end of the switching circuit, so that the power conversion circuit is connected to the DC energy storage device.

[0008] Preferably, the DC bus is connected to the DC side of the wind power converter.

[0009] Preferably, the controller is specifically used to control the power conversion circuit to operate in DC-AC mode when the target parameters meet the corresponding conditions; the target parameters include at least one of the following: receiving a preset adjustment instruction, the voltage of the DC bus, the grid frequency and the power change rate of the wind power converter.

[0010] Preferably, when the target parameter is the voltage of the DC bus, the controller is specifically configured to control the power conversion circuit to output AC power to charge the AC energy storage device when the voltage of the DC bus is greater than the maximum value of a preset voltage range; and to control the AC energy storage device to discharge when the voltage of the DC bus is less than the minimum value of the preset voltage range, so that the power conversion circuit outputs a DC voltage to stabilize the voltage of the DC bus.

[0011] Preferably, when the target parameter is the grid frequency, the controller is specifically used to control the power conversion circuit to charge or discharge the AC energy storage device to adjust the grid frequency when the rate of change of the grid frequency exceeds a preset value or the deviation of the grid frequency exceeds a preset deviation.

[0012] Preferably, when the target parameter is the power change rate of the wind power converter, the controller is specifically used to control the power conversion circuit to charge or discharge the AC energy storage device to stabilize the output power of the wind power converter when the change rate of the output power of the wind power converter is greater than a preset change rate.

[0013] Preferably, the controller is specifically configured to control the power conversion circuit to operate in a DC-DC mode upon receiving a DC bus voltage maintenance instruction, a peak regulation instruction or an energy transfer instruction.

[0014] Preferably, the switching circuit comprises a first set of switches and a second set of switches;

[0015] Two ends of the first group of switches are connected to the first end and the second end of the switching circuit respectively, and two ends of the second group of switches are connected to the first end and the third end of the switching circuit respectively.

[0016] Preferably, each phase of the power conversion circuit includes a half-bridge circuit, and each half-bridge circuit includes two controllable switching tubes connected in series.

[0017] The present application also provides a wind power converter, comprising an AC / DC circuit, a DC / AC circuit, and the hybrid energy storage converter device described above;

[0018] The input end of the AC / DC circuit is used to connect to the wind turbine generator, the output end of the AC / DC circuit is used to connect to the input end of the DC / AC circuit, and the output end of the DC / AC circuit is used to connect to the AC power grid;

[0019] The first end of the power conversion circuit in the hybrid energy storage and current conversion device is used to connect to the output end of the AC / DC circuit.

[0020] The present application also provides a control method for a hybrid energy storage converter device, the hybrid energy storage converter device comprising: a power conversion circuit, a switching circuit, and a controller; a first end of the power conversion circuit is used to connect to a DC bus; a second end of the power conversion circuit is connected to a first end of the switching circuit; a second end of the switching circuit is used to connect to an AC energy storage device, and a third end of the switching circuit is used to connect to a DC energy storage device;

[0021] include:

[0022] When the power conversion circuit is controlled to operate in a DC-AC mode, the first terminal of the switching circuit is controlled to be connected to the second terminal of the switching circuit, so that the power conversion circuit is connected to the AC energy storage device;

[0023] When the power conversion circuit is controlled to operate in a DC-DC mode, the first terminal of the switching circuit is controlled to be connected to the third terminal of the switching circuit, so that the power conversion circuit is connected to the DC energy storage device.

[0024] Preferably, controlling the power conversion circuit to operate in a DC-AC mode specifically includes:

[0025] When the target parameters meet the corresponding conditions, the power conversion circuit is controlled to operate in DC-AC mode; the target parameters include at least one of the following: receiving a preset adjustment instruction, the voltage of the DC bus, the grid frequency and the power change rate of the wind power converter.

[0026] Preferably, when the target parameters meet corresponding conditions, controlling the power conversion circuit to operate in a DC-AC mode specifically includes:

[0027] The target parameter is the voltage of the DC bus. When the voltage of the DC bus is greater than the maximum value of the preset voltage range, the power conversion circuit is controlled to output AC power to charge the AC energy storage device. When the voltage of the DC bus is less than the minimum value of the preset voltage range, the AC energy storage device is controlled to discharge so that the power conversion circuit outputs DC voltage to stabilize the voltage of the DC bus.

[0028] Preferably, when the target parameters meet corresponding conditions, controlling the power conversion circuit to operate in a DC-AC mode specifically includes:

[0029] The target parameter is the grid frequency. When the rate of change of the grid frequency exceeds a preset value or the deviation of the grid frequency exceeds a preset deviation, the power conversion circuit is controlled to charge or discharge the AC energy storage device to adjust the grid frequency.

[0030] Preferably, when the target parameters meet corresponding conditions, controlling the power conversion circuit to operate in a DC-AC mode specifically includes:

[0031] The target parameter is the power change rate of the wind power converter. When the change rate of the output power of the wind power converter is greater than the preset change rate, the power conversion circuit is controlled to charge or discharge the AC energy storage device to stabilize the output power of the wind power converter.

[0032] Preferably, controlling the power conversion circuit to operate in a DC-DC mode specifically includes:

[0033] When receiving a DC bus voltage maintenance instruction, a peak regulation instruction or an energy transfer instruction, the power conversion circuit is controlled to operate in a DC-DC mode.

[0034] It can be seen that this application has the following beneficial effects:

[0035] The hybrid energy storage device provided in the present application can realize AC energy storage for AC energy storage equipment and energy storage for DC energy storage equipment by using a set of power conversion circuits. In addition, the power conversion circuit is a bidirectional power conversion circuit, that is, it can output the electric energy of the DC bus to the energy storage device, and it can also transmit the electric energy of the energy storage device to the DC bus. The controller controls the working state of the power conversion circuit and can output AC power or DC power, specifically by controlling the switching state of the controllable switch tube in the power conversion circuit. When the power conversion circuit operates in DC-AC mode, the power conversion circuit and the AC energy storage device are connected by controlling the switch of the switching circuit. When the power conversion circuit operates in DC-DC mode, the power conversion circuit and the DC energy storage device are connected by controlling the switch of the switching circuit. Hybrid energy storage devices can realize both AC energy storage and DC energy storage. For example, in a wind power generation system, when needed, the energy of AC energy storage or DC energy storage can be fed back to the DC bus to meet the needs of the wind power generation system, such as frequency modulation or peak regulation, thereby stabilizing the voltage, frequency and power of the power grid and realizing a more flexible two-way flow of electric energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of a wind power generation system provided in this application;

[0037] Figure 2 A schematic diagram of a hybrid energy storage and current conversion device provided in an embodiment of the present application;

[0038] Figure 3 A schematic diagram of another hybrid energy storage and conversion device provided in an embodiment of the present application;

[0039] Figure 4 A schematic diagram of a wind power converter provided in an embodiment of the present application;

[0040] Figure 5 This is a flow chart of a control method for a hybrid energy storage converter device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the technical solution provided by this application, a specific application scenario is first introduced below.

[0042] The hybrid energy storage and conversion device provided in the embodiments of this application is not limited to specific application scenarios. Any DC power source can be used to store energy. The DC power source can be a photovoltaic array or a wind turbine. For ease of understanding, the application of the hybrid energy storage and conversion device in wind power generation is used as an example.

[0043] See also Figure 1 , which is a schematic diagram of a wind power generation system provided in this application.

[0044] The wind power generation system includes an alternating current direct current (ACDC) circuit 100 and a direct current alternating current (DCAC) circuit 200;

[0045] A first end of the ACDC circuit 100 is connected to the wind turbine generator, a second end of the ACDC circuit 100 is connected to a first end of the DCAC circuit 200 , and a second end of the DCAC circuit 200 is connected to the transformer T.

[0046] The ACDC circuit 100 is used to convert the alternating current output by the generator into direct current and output it to the DCAC circuit 200. The DCAC circuit 200 is used to convert direct current into alternating current, which is then transformed by the transformer T and connected to the grid.

[0047] When the hybrid energy storage converter device 300 provided in the embodiment of the present application is applied to a wind power generation system, the hybrid energy storage converter device 300 is connected to the second end of the ACDC circuit 100 , that is, connected to the DC bus on the DC side.

[0048] The hybrid energy storage converter provided in the embodiment of the present application can realize both AC energy storage and DC energy storage, and the AC energy storage and DC energy storage share a set of power conversion circuits, which has a higher degree of integration, saves the amount of hardware, saves the volume of the entire hybrid energy storage converter, and thus reduces costs.

[0049] The hybrid energy storage and conversion device provided in the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0050] See also Figure 2 , which is a schematic diagram of a hybrid energy storage and conversion device provided in an embodiment of the present application.

[0051] The hybrid energy storage and current conversion device provided in this embodiment includes: a power conversion circuit 10, a switching circuit 20 and a controller 30;

[0052] The first end of the power conversion circuit 10 is used to connect to the DC bus; the second end of the power conversion circuit 10 is connected to the first end of the switching circuit 20;

[0053] The second end of the switching circuit 20 is used to connect to the AC energy storage device 40, and the third end of the switching circuit 20 is used to connect to the DC energy storage device 50;

[0054] The controller 30 is used to control the power conversion circuit 10 to operate in the DC-AC mode, thereby controlling the first end of the switching circuit 20 to be connected to the second end of the switching circuit 20, so that the power conversion circuit 10 is connected to the AC energy storage device 40; and is also used to control the power conversion circuit 10 to operate in the DC-DC mode, thereby controlling the first end of the switching circuit 20 to be connected to the third end of the switching circuit 20, so that the power conversion circuit 10 is connected to the DC energy storage device 50.

[0055] For example, the DC bus is connected to the DC side of the wind power converter; the AC energy storage device includes a motor and a flywheel; the flywheel can also be replaced by hydraulic pneumatic energy storage, and the DC energy storage device includes an energy storage battery.

[0056] AC energy storage can take the form of kinetic energy storage, enabling rapid power regulation. This means AC energy storage offers advantages such as fast dynamic response and long lifespan. AC energy storage can utilize motors to convert electrical energy into mechanical energy, and mechanical energy into energy storage media, such as flywheels or hydraulic and pneumatic energy storage. Closed-loop control of the motor speed enables rapid adjustment of the flywheel speed. When the flywheel speed increases, electrical energy is converted into flywheel kinetic energy, a charging mode. When the flywheel speed decreases, the flywheel kinetic energy is converted into electrical energy output, a discharge mode.

[0057] The motor is a synchronous motor, an induction motor, or other AC motor, which can realize real-time adjustment of speed and torque, and has the ability to quickly convert mechanical energy and electrical energy, thereby realizing charging or discharging of AC energy storage mode.

[0058] DC energy storage has a large energy unit, can achieve long-term power throughput, and realize energy conversion between electrical energy and DC energy storage media. The storage medium can be electrochemical batteries, water electrolysis to produce hydrogen, electromagnetic energy storage, etc.

[0059] The hybrid energy storage device provided in the embodiment of the present application can realize AC energy storage for AC energy storage equipment and energy storage for DC energy storage equipment by using a set of power conversion circuits. In addition, the power conversion circuit is a bidirectional power conversion circuit, that is, it can output the electric energy of the DC bus to the energy storage device, and can also transmit the electric energy of the energy storage device to the DC bus. The controller controls the working state of the power conversion circuit and can output AC or DC power, specifically by controlling the switching state of the controllable switch tube in the power conversion circuit. When the power conversion circuit operates in DC-AC mode, the power conversion circuit and the AC energy storage device are connected by controlling the switch of the switching circuit. When the power conversion circuit operates in DC-DC mode, the power conversion circuit and the DC energy storage device are connected by controlling the switch of the switching circuit. The power conversion circuit included in the hybrid energy storage device can switch between two working modes, thereby realizing two completely different circuit functions, combining the two into one. Therefore, the circuit integration is higher, hardware area and volume are saved, and costs are reduced.

[0060] The following is an introduction using a three-phase half-bridge circuit as an example. Figure 3 , which is a schematic diagram of another hybrid energy storage and conversion device provided in an embodiment of the present application.

[0061] The power conversion circuit includes three bridge arms, one corresponding to each bridge arm, and each bridge arm includes two controllable switch tubes connected in series, such as Figure 3 As shown, the three-phase power conversion circuit includes six controllable switches, numbered 1 through 6. A controller sends drive signals to the controllable switches in the power conversion circuit, controlling the circuit to operate in either DC-AC or DC-DC mode.

[0062] Take the AC energy storage device including the motor M and the flywheel F as an example, and the DC energy storage device including the energy storage battery as an example.

[0063] In this embodiment, the switching circuit including the first set of switches K1 and the second set of switches K2 is used as an example for description. In addition, the switching circuit may also be in other forms as long as it can achieve path switching.

[0064] The first set of switches K1 has two terminals connected to the first and second terminals of the switching circuit, respectively. The second set of switches K2 has two terminals connected to the first and third terminals of the switching circuit, respectively. It should be understood that for a three-phase system, both the first and second sets of switches K1 and K2 include three phases, and the switch states of the two sets of switches cannot be closed simultaneously, but can be open simultaneously, or one closed and the other open. For example, during DC energy storage, K1 is closed and K2 is open. During AC energy storage, K1 is open and K2 is closed.

[0065] The hybrid energy storage and current conversion device provided in this embodiment further includes: a filter circuit; Figure 3 As shown, the filtering circuit includes a filtering inductor L.

[0066] The filter circuit is connected between the power conversion circuit 10 and the first end of the switching circuit 20 . For example, L is connected between the output end of the power conversion circuit 10 and the first end of the switching circuit 20 .

[0067] In addition, the power conversion circuit 10 further includes an input capacitor C1, which is connected between the positive input terminal and the negative input terminal of the power conversion circuit 10 and can also serve as a DC bus capacitor. The positive busbar of the DC bus is DC+, and the negative busbar is DC-. The positive input terminal and the negative input terminal of the power conversion circuit 10 are connected to DC+ and DC-, respectively.

[0068] A capacitor C2 is also connected between the positive terminal B+ and the negative terminal B- of the energy storage battery.

[0069] The switching between the AC-side energy storage mode and the DC-side energy storage mode can be directly controlled by the upper-level controller, participating in different control scenarios. When the upper-level controller is involved in frequency regulation or power smoothing, it issues an AC energy storage instruction, and the power conversion circuit in the hybrid energy storage conversion device operates in the AC energy storage mode. When the upper-level controller is involved in peak regulation or energy transfer, it issues a DC energy storage instruction, and the power conversion circuit in the hybrid energy storage conversion device operates in the DC energy storage mode. In a wind power generation system, for example, the upper-level controller can be the controller of the wind power converter or the controller of a higher-level wind power station.

[0070] The following first introduces the scenario where the power conversion circuit operates in DC-AC mode, that is, the power conversion circuit is connected to an AC energy storage device.

[0071] The controller 30 is specifically configured to control the power conversion circuit 10 to operate in the DC-AC mode when target parameters meet corresponding conditions. The target parameters include at least one of the following: a received preset adjustment instruction, a DC bus voltage, a grid frequency, and a power change rate of the wind turbine converter. The preset adjustment instruction instructs the power conversion circuit to switch to the DC-AC mode.

[0072] When the target parameter is the DC bus voltage, the controller is specifically configured to control the power conversion circuit 10 to output AC power to charge the AC energy storage device when the DC bus voltage is greater than the maximum value of a preset voltage range; and to control the AC energy storage device to discharge when the DC bus voltage is less than the minimum value of the preset voltage range, so that the power conversion circuit 10 outputs a DC voltage to stabilize the DC bus voltage. It should be understood that the DC bus voltage, i.e., the voltage at the first terminal of the power conversion circuit, can be directly acquired for DC bus regulation.

[0073] The maximum value of the preset voltage range may be determined according to actual protection and control strategies, for example, the safe operating upper limit of the DC voltage may be selected.

[0074] When the target parameter is the grid frequency, the controller 30 is specifically used to control the power conversion circuit 10 to charge or discharge the AC energy storage device to adjust the grid frequency when the rate of change of the grid frequency exceeds a preset value or the deviation of the grid frequency exceeds a preset deviation.

[0075] The rate of change of grid frequency corresponds to inertia, and grid frequency deviation corresponds to primary frequency regulation. That is, when the grid frequency exceeds the inertia or primary frequency regulation dead zone, AC energy storage is activated to charge or discharge, replenishing the power difference between inertia and frequency deviation, thus participating in the inertia frequency regulation service.

[0076] When the target parameter is the wind power converter power rate of change, controller 30 is specifically configured to control power conversion circuit 10 to charge or discharge the AC energy storage device to stabilize the wind power converter output power when the wind power converter output power rate of change exceeds a preset rate of change. It should be understood that the wind power converter output power can be sampled by collecting voltage and current.

[0077] The system participates in smooth control of grid-connected power, power surges, and power dips based on a preset conversion rate. For example, it can compare the current output power with the previous output power. When the power change rate exceeds the preset rate, the AC energy storage is activated to charge or discharge, absorbing or emitting power, i.e., reverse power flow, thereby achieving smooth control of the wind turbine converter's output power.

[0078] The above introduction is about the control of AC energy storage mode according to target parameters. The following introduces the control of DC energy storage mode.

[0079] The control of the DC energy storage mode is mainly to control the power conversion circuit to operate in DC-DC mode according to the instructions of the upper control.

[0080] The controller 30 is specifically configured to control the power conversion circuit 10 to operate in a DC-DC mode upon receiving a DC bus voltage maintenance instruction, a peak regulation instruction, or an energy transfer instruction.

[0081] The target parameter is the energy control of the wind turbine. When wind power generation is limited, DC energy storage is used to absorb the electricity of the wind turbine to alleviate power curtailment. When wind power is connected to the grid, DC energy storage serves as a grid-connected energy supplement to increase power generation.

[0082] The target parameter is the power reserve of deep frequency modulation. DC energy is exchanged on the interconnected grid lines through grid-connected inverters to offset the difference in grid frequency.

[0083] The target parameter is to maintain the DC voltage. The power conversion circuit 10 provides a stable DC voltage and power for the DC bus, and provides a DC voltage and power to achieve black start and stable operation of the AC interconnected power grid.

[0084] Based on the hybrid energy storage converter device provided in the above embodiment, the embodiment of the present application further provides a wind power converter, which is described in detail below with reference to the accompanying drawings.

[0085] See also Figure 4 , which is a schematic diagram of a wind power converter provided in an embodiment of the present application.

[0086] The wind power converter provided in this embodiment includes an ACDC circuit 100, a DCAC circuit 200, and the hybrid energy storage converter 300 described above;

[0087] The input end of the ACDC circuit 100 is used to connect to the wind turbine, the output end of the ACDC circuit 100 is used to connect to the input end of the DCAC circuit 200, and the output end of the DCAC circuit 200 is used to connect to the AC power grid;

[0088] The first end of the power conversion circuit 10 in the hybrid energy storage and current conversion device 300 is used to connect to the output end of the ACDC circuit 100 .

[0089] The wind power converter provided in the embodiment of the present application includes a hybrid energy storage converter 300, which can be integrated with the ACDC circuit 100 and the DCAC circuit 200, or can be set independently. Since the wind power converter is provided with a hybrid energy storage converter, it can realize both AC energy storage and DC energy storage, and can feed back the energy of AC energy storage or DC energy storage to the DC bus when the wind power generation system needs it, so as to meet the needs of the wind power generation system, such as frequency modulation or peak regulation, thereby stabilizing the voltage, frequency and power of the power grid, and realizing the two-way flow of electric energy more flexibly. When a fast response is required, the power conversion circuit can be controlled to operate in DC-AC mode, and when long-term energy storage is required, the power conversion circuit can be controlled to operate in DC-DC mode.

[0090] Based on the hybrid energy storage converter and wind power converter provided in the above embodiments, the present application also provides a control method for the hybrid energy storage converter, which is described in detail below with reference to the accompanying drawings.

[0091] See also Figure 5 , which is a flow chart of a control method for a hybrid energy storage conversion device provided in an embodiment of the present application.

[0092] This embodiment provides a control method for a hybrid energy storage converter device, wherein the hybrid energy storage converter device includes: a power conversion circuit, a switching circuit, and a controller; a first end of the power conversion circuit is used to connect to a DC bus; a second end of the power conversion circuit is connected to a first end of the switching circuit; a second end of the switching circuit is used to connect to an AC energy storage device, and a third end of the switching circuit is used to connect to a DC energy storage device;

[0093] include:

[0094] S501: When controlling the power conversion circuit to operate in a DC-AC mode, controlling the first terminal of the switching circuit to be connected to the second terminal of the switching circuit, so that the power conversion circuit is connected to the AC energy storage device;

[0095] S502: When controlling the power conversion circuit to operate in a DC-DC mode, controlling the first terminal of the switching circuit to be connected to the third terminal of the switching circuit, so that the power conversion circuit is connected to the DC energy storage device.

[0096] Control the power conversion circuit to operate in DC-AC mode, specifically including:

[0097] When the target parameters meet the corresponding conditions, the power conversion circuit is controlled to operate in DC-AC mode; the target parameters include at least one of the following: receiving a preset adjustment instruction, the voltage of the DC bus, the grid frequency and the power change rate of the wind power converter.

[0098] When the target parameters meet the corresponding conditions, the power conversion circuit is controlled to operate in the DC-AC mode, specifically including:

[0099] The target parameter is the voltage of the DC bus. When the voltage of the DC bus is greater than the maximum value of the preset voltage range, the power conversion circuit is controlled to output AC power to charge the AC energy storage device. When the voltage of the DC bus is less than the minimum value of the preset voltage range, the AC energy storage device is controlled to discharge so that the power conversion circuit outputs DC voltage to stabilize the voltage of the DC bus.

[0100] When the target parameters meet the corresponding conditions, the power conversion circuit is controlled to operate in the DC-AC mode, specifically including:

[0101] The target parameter is the grid frequency. When the rate of change of the grid frequency exceeds a preset value or the deviation of the grid frequency exceeds a preset deviation, the power conversion circuit is controlled to charge or discharge the AC energy storage device to adjust the grid frequency.

[0102] When the target parameters meet the corresponding conditions, the power conversion circuit is controlled to operate in the DC-AC mode, specifically including:

[0103] The target parameter is the power change rate of the wind power converter. When the change rate of the output power of the wind power converter is greater than the preset change rate, the power conversion circuit is controlled to charge or discharge the AC energy storage device to stabilize the output power of the wind power converter.

[0104] Control the power conversion circuit to operate in DC-DC mode, specifically including:

[0105] When receiving a DC bus voltage maintenance instruction, a peak regulation instruction or an energy transfer instruction, the power conversion circuit is controlled to operate in a DC-DC mode.

[0106] This control method enables both AC and DC energy storage. Furthermore, when needed by the wind power generation system, the AC or DC stored energy can be fed back to the DC bus to meet the needs of the wind power generation system, such as frequency modulation or peak regulation. This stabilizes the voltage, frequency, and power of the power grid and enables more flexible bidirectional flow of electrical energy. When a rapid response is required, the power conversion circuit can be controlled to operate in DC-AC mode. When long-term energy storage is required, the power conversion circuit can be controlled to operate in DC-DC mode.

[0107] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hybrid energy storage and current conversion device, characterized in that: include: Power conversion circuits, switching circuits and controllers; The first end of the power conversion circuit is used to connect to the DC bus; the second end of the power conversion circuit is connected to the first end of the switching circuit; The second end of the switching circuit is used to connect to an AC energy storage device, and the third end of the switching circuit is used to connect to a DC energy storage device; The controller is used to control the first end of the switching circuit to be connected to the second end of the switching circuit when the power conversion circuit operates in a DC-AC mode, so that the power conversion circuit is connected to the AC energy storage device; and is also used to control the first end of the switching circuit to be connected to the third end of the switching circuit when the power conversion circuit operates in a DC-DC mode, so that the power conversion circuit is connected to the DC energy storage device.

2. The hybrid energy storage and flow conversion device according to claim 1, characterized in that: The DC bus is connected to the DC side of the wind power converter.

3. The hybrid energy storage and flow conversion device according to claim 2, characterized in that: The controller is specifically used to control the power conversion circuit to operate in a DC-AC mode when a target parameter meets a corresponding condition; the target parameter includes at least one of the following: receiving a preset adjustment instruction, the voltage of the DC bus, the grid frequency, and the power change rate of the wind power converter.

4. The hybrid energy storage and flow conversion device according to claim 3, characterized in that: When the target parameter is the voltage of the DC bus, the controller is specifically configured to control the power conversion circuit to output AC power to charge the AC energy storage device when the voltage of the DC bus is greater than a maximum value of a preset voltage range; and to control the AC energy storage device to discharge when the voltage of the DC bus is less than a minimum value of the preset voltage range, so that the power conversion circuit outputs a DC voltage to stabilize the voltage of the DC bus.

5. The hybrid energy storage and conversion device according to claim 3, characterized in that: When the target parameter is the grid frequency, the controller is specifically used to control the power conversion circuit to charge or discharge the AC energy storage device to adjust the grid frequency when the rate of change of the grid frequency exceeds a preset value or the deviation of the grid frequency exceeds a preset deviation.

6. The hybrid energy storage and conversion device according to claim 3, characterized in that: When the target parameter is the power change rate of the wind power converter, the controller is specifically used to control the power conversion circuit to charge or discharge the AC energy storage device to stabilize the output power of the wind power converter when the change rate of the output power of the wind power converter is greater than a preset change rate.

7. The hybrid energy storage and conversion device according to any one of claims 1 to 6, characterized in that: The controller is specifically configured to control the power conversion circuit to operate in a DC-DC mode upon receiving a DC bus voltage maintenance instruction, a peak regulation instruction, or an energy transfer instruction.

8. The hybrid energy storage and current conversion device according to any one of claims 1 to 6, characterized in that: The switching circuit includes a first set of switches and a second set of switches; Two ends of the first group of switches are connected to the first end and the second end of the switching circuit respectively, and two ends of the second group of switches are connected to the first end and the third end of the switching circuit respectively.

9. The hybrid energy storage and current conversion device according to any one of claims 1 to 6, characterized in that: Each phase of the power conversion circuit includes a half-bridge circuit, and each half-bridge circuit includes two controllable switching tubes connected in series.

10. A wind power converter, characterized in that: comprising an AC-DC circuit, a DC-AC circuit, and a hybrid energy storage and current conversion device according to any one of claims 1 to 9; The input end of the AC / DC circuit is used to connect to a wind turbine generator, the output end of the AC / DC circuit is used to connect to the input end of the DC / AC circuit, and the output end of the DC / AC circuit is used to connect to an AC power grid; The first end of the power conversion circuit in the hybrid energy storage and current conversion device is used to connect to the output end of the AC / DC circuit.

11. A control method for a hybrid energy storage converter, characterized in that: The hybrid energy storage and current conversion device includes: a power conversion circuit, a switching circuit and a controller; the first end of the power conversion circuit is used to connect to the DC bus; the second end of the power conversion circuit is connected to the first end of the switching circuit; the second end of the switching circuit is used to connect to the AC energy storage device, and the third end of the switching circuit is used to connect to the DC energy storage device; include: When controlling the power conversion circuit to operate in a DC-AC mode, controlling the first end of the switching circuit to be connected to the second end of the switching circuit, so that the power conversion circuit is connected to the AC energy storage device; When the power conversion circuit is controlled to operate in a DC-DC mode, the first end of the switching circuit is controlled to be connected to the third end of the switching circuit, so that the power conversion circuit is connected to the DC energy storage device.

12. The control method according to claim 11, characterized in that: The DC bus is connected to the DC side of the wind power converter, and the controlling the power conversion circuit to operate in a DC-AC mode specifically includes: When the target parameters meet the corresponding conditions, the power conversion circuit is controlled to operate in DC-AC mode; the target parameters include at least one of the following: receiving a preset adjustment instruction, the voltage of the DC bus, the grid frequency and the power change rate of the wind power converter.

13. The control method according to claim 12, characterized in that: When the target parameter satisfies the corresponding condition, controlling the power conversion circuit to operate in the DC-AC mode specifically includes: The target parameter is the voltage of the DC bus. When the voltage of the DC bus is greater than the maximum value of a preset voltage range, the power conversion circuit is controlled to output AC power to charge the AC energy storage device. When the voltage of the DC bus is less than the minimum value of the preset voltage range, the AC energy storage device is controlled to discharge so that the power conversion circuit outputs a DC voltage to stabilize the voltage of the DC bus.

14. The control method according to claim 12, characterized in that: When the target parameter satisfies the corresponding condition, controlling the power conversion circuit to operate in the DC-AC mode specifically includes: The target parameter is the grid frequency. When the rate of change of the grid frequency exceeds a preset value or the deviation of the grid frequency exceeds a preset deviation, the power conversion circuit is controlled to charge or discharge the AC energy storage device to adjust the grid frequency.

15. The control method according to claim 12, characterized in that: When the target parameter satisfies the corresponding condition, controlling the power conversion circuit to operate in the DC-AC mode specifically includes: The target parameter is the power change rate of the wind power converter. When the change rate of the output power of the wind power converter is greater than a preset change rate, the power conversion circuit is controlled to charge or discharge the AC energy storage device to stabilize the output power of the wind power converter.

16. The control method according to any one of claims 11 to 15, characterized in that: The controlling the power conversion circuit to operate in a DC-DC mode specifically includes: When a DC bus voltage maintenance instruction, a peak regulation instruction or an energy transfer instruction is received, the power conversion circuit is controlled to operate in a DC-DC mode.

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