Energy storage system, power unit, control method, equipment, medium and product

Abstract

The invention provides an energy storage system, a power unit, a control method, equipment, a medium and a product, and the power unit comprises an energy storage circuit, a filter circuit and a voltage conversion circuit. The filter circuit can simultaneously filter high-frequency components larger than a first frequency value caused by the switching frequency of the voltage conversion circuit in the direct current of the energy storage circuit, and filter double-frequency components equal to a second frequency value caused by the alternating current of the power grid, so that harmonic components in the direct current of the energy storage circuit are reduced; therefore, the loss of the harmonic component to the energy storage circuit is reduced, and the continuous and stable operation of the whole energy storage system is ensured.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to an energy storage system, power unit, control method, equipment, medium and product. Background Art

[0002] New power systems utilize new generation devices, such as wind and photovoltaic power, to generate electricity, which is then transmitted to loads via the power grid. Because the energy generated by these devices fluctuates and exhibits randomness over time, energy storage systems are also integrated into the power system. Connected to the power grid, these systems can store energy when the generation devices are generating high levels of power and supply it to the grid when the generation is low, ensuring continuous and stable operation of the loads and enabling more flexible control and distribution of power.

[0003] However, when an energy storage system is connected to the grid, the DC current in the energy storage circuit contains a large number of harmonic components. These harmonic components enter the energy storage circuit, causing it to lose power more quickly, thus affecting the normal operation of the entire energy storage system. How to more effectively filter out harmonic components in the DC current is a technical problem that needs to be solved in this field. Summary of the Invention

[0004] The present application provides an energy storage system, a power unit, a control method, a device, a medium and a product to more effectively filter out harmonic components in the direct current of an energy storage circuit.

[0005] In a first aspect, the present application provides a power unit for an energy storage system, comprising an energy storage circuit, a voltage conversion circuit, and a filter circuit. The energy storage circuit is configured to store electrical energy; the voltage conversion circuit is configured to convert the direct current of the energy storage circuit into alternating current from a power grid; and the filter circuit is disposed between the energy storage circuit and the voltage conversion circuit to filter out a first harmonic component generated by the voltage conversion circuit and a second harmonic component generated by the alternating current from the power grid, included in the current of the energy storage circuit.

[0006] The second aspect of the present application provides an energy storage system, comprising: a first AC branch, comprising a first AC inductor connected in series and a plurality of power units as described in the first aspect of the present application; a second AC branch, comprising a second AC inductor connected in series and a plurality of power units as described in the first aspect of the present application; and a third AC branch, comprising a third AC inductor connected in series and a plurality of power units as described in the first aspect of the present application.

[0007] The third aspect of the present application provides a control method for a power unit, which is used to control the power unit provided in the first aspect of the present application, and the control method includes: determining the real-time modulation ratio of the voltage conversion circuit; determining the current value and current ripple rate of the first harmonic component; when the current ripple rate is greater than a preset threshold, adjusting the switching frequency of the voltage conversion circuit according to the real-time modulation ratio to reduce the first harmonic component generated by the voltage conversion circuit included in the current of the energy storage circuit.

[0008] The fourth aspect of the present application provides an electronic device comprising: a memory and a processor; the memory stores computer-executable instructions; the processor executes the computer-executable instructions stored in the memory, so that the processor executes the method described in the third aspect of the present application.

[0009] A fifth aspect of the present application provides a computer-readable storage medium storing computer-executable instructions, which, when executed, implement the method described in the third aspect of the present application.

[0010] In a sixth aspect, the present application provides a computer program product, including a computer program, which implements the method described in the third aspect of the present application when executed.

[0011] In summary, the energy storage system, power unit, control method, equipment, medium and product provided by the present application can simultaneously filter out the high-frequency components greater than the first frequency value caused by the switching frequency of the voltage conversion circuit in the DC current of the energy storage circuit, and filter out the double-frequency components equal to the second frequency value caused by the AC power of the power grid, through the provided filtering circuit. Therefore, the harmonic components in the DC current of the energy storage circuit are reduced, thereby reducing the loss caused by the harmonic components to the energy storage circuit, and ensuring the continuous and stable operation of the entire energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0013] Figure 1 A schematic diagram of the application scenario of this application;

[0014] Figure 2 A schematic structural diagram of an embodiment of an energy storage system provided in this application;

[0015] Figure 3 This is a structural diagram of a power unit in the prior art;

[0016] Figure 4 Schematic diagram of current change of energy storage circuit in the prior art;

[0017] Figure 5 A schematic diagram of the structure of a power unit of an energy storage system provided in this application;

[0018] Figure 6 A schematic diagram of current changes in the energy storage circuit provided in this application;

[0019] Figure 7 A schematic structural diagram of another embodiment of a power unit of the energy storage system provided in this application;

[0020] Figure 8 A schematic diagram of the circuit structure of an embodiment of a power unit provided in this application;

[0021] Figure 9 A flow chart of an embodiment of a power unit control method provided in this application

[0022] Figure 10 This is a schematic diagram of the structure of an electronic device provided in this application. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

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

[0025] Figure 1 This is a schematic diagram of the application scenario of this application, such as Figure 1The schematic diagram of the structure of a new power system based on new energy sources is shown. The power generation device 3 can be a wind power generation device or a photovoltaic power generation device, etc. The electricity generated by the power generation device 3 is provided to the load 4 via the power grid 2. Due to the temporal fluctuation and randomness of the electricity generated by the power generation device 3, some power systems are also equipped with an energy storage system 1, which is connected to the power grid 2. The energy storage system 1 can store excess electricity when the power generation device 3 generates a large amount of electricity. When the power generation device 3 generates less electricity due to environmental factors, the energy storage system 1 can provide electricity to the load 4 via the power grid 2, thereby ensuring the continuous and stable operation of the load 4 and achieving more flexible control and distribution of the electricity generated by the power generation device 3.

[0026] Figure 2 This is a schematic diagram of the structure of an embodiment of the energy storage system provided in this application, as shown in FIG. Figure 2 Shown Figure 1 The specific structure of the power grid 2 and the energy storage system 1, wherein the power grid 2 supports three-phase AC power, and the three interfaces corresponding to the three-phase AC power are respectively denoted as Ua, Ub and Uc.

[0027] like Figure 2 The energy storage system 1 shown includes a first AC branch, a second AC branch, and a third AC branch, each connected to three interfaces of the three-phase AC power grid 2. The other ends of the first, second, and third AC branches are also connected together. The first AC branch includes a first AC inductor L1 and multiple power units 10. Taking n power units 10 as an example, these are denoted as SM11, SM12, ..., SM1n. The second AC branch includes a second AC inductor L2 and multiple power units 10. Also taking n power units 10 as an example, these are denoted as SM21, SM22, ..., SM2n. The third AC branch includes a third AC inductor L3 and multiple power units 10. Also taking n power units 10 as an example, these are denoted as SM31, SM32, ..., SM3n.

[0028] Figure 3 This is a schematic diagram of the structure of a power unit in the prior art, such as Figure 3 The power unit shown can be used for Figure 2 In the energy storage system shown. Figure 3The power unit 10 shown includes an energy storage circuit 11 and a voltage conversion circuit 13, wherein the energy storage circuit 11 can be a battery, etc., for storing electrical energy. The voltage conversion circuit 13 is used to convert the direct current supported by the energy storage circuit 11 to the alternating current supported by the grid side, for example, converting the direct current voltage Udc to the alternating current voltage Uo. In some technologies, the voltage conversion circuit 13 can be implemented by a power conversion system (PCS), which also includes other circuits not shown in the figure.

[0029] In such Figure 3 When the power unit 10 shown is in operation, the side where the voltage conversion circuit 13 is connected to the energy storage circuit 11 not only flows with direct current, but also flows with a double frequency current caused by the alternating current of the grid 2, and high-order harmonic currents caused by the switching frequency of the voltage conversion circuit 13. These harmonic currents cause the current flowing through the energy storage circuit 11 to change. These changes include changes in the input current when the energy storage circuit 11 is charging, and changes in the output current when the energy storage circuit 11 is discharging.

[0030] For example, Figure 4 The figure is a schematic diagram of the current changes in the energy storage circuit in the prior art, in which the ideal current input or output of the energy storage circuit 11 is id, and under the influence of the double frequency current and higher harmonic current, the actual current input or output of the energy storage circuit 11 is idcs. When the harmonic components in the actual current of the energy storage circuit 11 flow directly into the energy storage circuit 11, it will cause losses to the energy storage circuit 11 and cause the temperature of the energy storage circuit 11 to rise, reducing the service life and safety of the energy storage circuit 11, and affecting the normal operation of the entire energy storage system. Therefore, how to effectively filter out the harmonic components in the DC current of the energy storage circuit 11 in the power unit 10 of the energy storage system 1 is a technical problem that needs to be solved in this field.

[0031] The following specific embodiments are used to describe the technical solution of the present application in detail. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0032] Figure 5 A schematic diagram of the structure of a power unit of an energy storage system provided in this application is shown as follows: Figure 5 The power unit 10 shown can be used in Figure 1 and Figure 2 Specifically, Figure 5 The power unit 10 shown includes an energy storage circuit 11 , a filter circuit 12 and a voltage conversion circuit 13 .

[0033] The energy storage circuit 11 is used to store electrical energy. The energy storage circuit 11 may specifically be a battery pack or the like.

[0034] The voltage conversion circuit 13 is used to convert the DC power supported by the energy storage circuit 11 to the AC power supported by the grid. For example, when the energy storage circuit 11 is charging, the voltage conversion circuit 13 is used to convert the AC power to DC power; when the energy storage circuit 11 is discharging, the voltage conversion circuit 13 is used to convert the DC power to AC power.

[0035] The filter circuit 12 is provided between the energy storage circuit 11 and the voltage conversion circuit 13 , that is, the energy storage circuit 11 is connected to the voltage conversion circuit 13 through the filter circuit 12 .

[0036] In one embodiment, the filter circuit 12 is a passive filter circuit.

[0037] The filter circuit 12 provided in the embodiment of the present application can be used to filter out the harmonic components of the DC current of the energy storage circuit 11. Specifically, the harmonic components that can be filtered out by the filter circuit 12 include: the first harmonic component generated by the voltage conversion circuit 13, and the second harmonic component generated by the AC power of the grid 2.

[0038] Specifically, the first harmonic component refers to a high-frequency harmonic current greater than a first frequency value, and the second harmonic component refers to a double frequency current having a frequency value equal to a second frequency value, wherein the second frequency value is less than the first frequency value.

[0039] For example, the filter circuit 12 may filter out the first harmonic component greater than the first frequency value in the direct current of the energy storage circuit 11 by low-pass filtering.

[0040] At the same time, the filter circuit 12 can also filter out the second harmonic component of the specified second frequency value.

[0041] In one embodiment, the second harmonic component may be a double frequency current included in the DC current of the energy storage circuit 11. For example, when the switching frequency of the voltage conversion circuit 13 is 50 Hz, the frequency of the double frequency current is 100 Hz, that is, the second frequency value may be 100 Hz.

[0042] Figure 6 This is a schematic diagram of current changes in the energy tank circuit provided in the present application, wherein the DC current IDCs of the energy tank circuit 11 includes a first harmonic component greater than the first frequency value and a second harmonic component equal to the second frequency value. After the DC current IDCs of the energy tank circuit 11 is processed by the filter circuit 12 to remove the first and second harmonic components in the DC current IDCs of the energy tank circuit 11, the DC current IDC output by the filter circuit 12 has a smoother time domain waveform than the DC current IDCs before filtering, and is closer to the ideal DC current IDC of the energy tank circuit 11.

[0043] In summary, in the power unit 10 of the energy storage system 1 provided in this embodiment, the filter circuit 12 is provided to simultaneously filter out the high-frequency components greater than the first frequency value in the DC current of the energy storage circuit 11, and filter out the double frequency components equal to the second frequency value in the DC current of the energy storage circuit 11. This reduces the harmonic components in the DC current of the energy storage circuit 11, thereby reducing the loss caused by the harmonic components flowing into the energy storage circuit 11 and preventing the temperature of the energy storage circuit 11 from rising due to the harmonic components, thereby ensuring the service life and safety performance of the energy storage circuit 11 and ensuring the continuous and stable operation of the entire energy storage system 1. At the same time, the filter circuit 11 provided in this embodiment achieves filtering of two harmonic components through a single circuit, reducing the structural complexity of the filter circuit 12, and not introducing other interference sources into the power unit 10, which is more conducive to the application and promotion of the power unit 10 and the energy storage system in which it is located.

[0044] Figure 7 This is a structural diagram of another embodiment of the power unit of the energy storage system provided by this application, as shown in FIG. Figure 7 The power unit 10 shown is Figure 5 Based on the above, the filter circuit 12 specifically includes a first filter branch 121 and a second filter branch 122. The first filter branch 121 and the second filter branch 122 are connected between the energy storage circuit 11 and the voltage conversion circuit 13 respectively.

[0045] The first filter branch 121 is used to filter out the first harmonic component with a frequency greater than the first frequency value in the DC current of the energy storage circuit 11. The first filter branch 121 can also be called a low-pass filter branch.

[0046] The second filter branch 122 is used to filter out the second harmonic component having a frequency value equal to the second frequency value in the DC current of the energy storage circuit 11. The second filter branch 122 can also be called a single-tuned filter branch.

[0047] In summary, the power unit provided in this embodiment respectively filters out the first harmonic component and the second harmonic component in the DC current of the energy storage circuit 11 by setting up two filtering branches, so that the processing of filtering out the two harmonic components can be implemented simultaneously and in parallel, thereby improving the filtering efficiency of the filtering circuit for harmonic components.

[0048] Figure 8 This is a schematic diagram of the circuit structure of an embodiment of the power unit provided in this application, as shown in FIG. Figure 8 Shown in Figure 7 The power unit 10 shown is a specific circuit implementation.

[0049] like Figure 8 As shown, the first filtering branch 121 includes: a first inductor L smand the first capacitor C sm , where the first inductor L sm The first end of the first inductor L is connected to the first end of the energy storage circuit 11. sm The second end is connected to the first capacitor C sm The first end of the voltage conversion circuit 13 and the first end of the first capacitor C sm The second end of the voltage converter circuit 13 is connected to the second end of the energy storage circuit 11 and the second end of the voltage conversion circuit 13.

[0050] The second filtering branch 122 includes: a second inductor L T and the second capacitor C T , where the second inductor L T The first end of the second inductor L is connected to the first end of the energy storage circuit 11. T The second end is connected to the second capacitor C T The first end of the second capacitor C T The second end of the voltage converter circuit 13 is connected to the second end of the energy storage circuit 11 and the second end of the voltage conversion circuit 13.

[0051] It can be seen that the first filtering branch 121 includes a first inductor L connected in series. sm and the first capacitor C sm , forming a low-pass filter, which can be used to filter out the high-frequency ripple current and part of the double-frequency ripple current generated by the voltage conversion circuit 13. The second filtering branch 122 includes a second inductor L connected in series. T and the second capacitor C T , forming an LC series resonant circuit, which can be used to filter out the double frequency ripple current. At the same time, the second filtering branch 122 and the first capacitor C sm In addition, Rdc is the internal resistance of the energy storage circuit 11.

[0052] In this embodiment, the voltage conversion circuit 13 is an H-bridge circuit. The H-bridge circuit includes four parallel-connected switch structures: a, b, c, and d. Each switch structure can be a transistor, an insulated-gate bipolar transistor (IGBT), or the like. The control circuit 130 of the voltage conversion circuit 13 controls each switch structure ad in the H-bridge circuit to turn on and off according to a switching frequency. The process of turning switch structures ad on and off according to the switching frequency results in the presence of a double frequency component in the DC current of the energy tank circuit 11.

[0053] In one embodiment, if Figure 8The first inductor and the first capacitor of the first filter branch 121 shown are determined according to the preset modulation ratio and switching frequency of the voltage conversion circuit 13, and the performance requirement parameters of the filter circuit 12 for the first harmonic component and the performance requirement parameters for the second harmonic component.

[0054] For example, the first inductor L sm and the first capacitor C sm Determined by the following formulas 1 and 2:

[0055]

[0056] Wherein, M is the preset modulation ratio of the voltage conversion circuit 13. m is the peak current of the phase current of grid 2. dc is the H-bridge DC voltage of the voltage conversion circuit 13. h =4πf c , f c is the switching frequency of the switch structure ad in the voltage conversion circuit 13. i_ωh is the performance requirement parameter of the filter circuit 12 for components greater than the first frequency value, γ u_ω2 is the performance requirement parameter of the filter circuit 12 for the component of the second frequency value. i_ωh and γ u_ω2 Typically set to a constant of no more than 1%.

[0057] In addition, due to the first inductance L sm The second filter branch 122 and the first capacitor C are connected in series. sm Although the oscillation of DC current at the double frequency can be effectively avoided, the first inductor L sm A large amount of double frequency current will flow through the first inductor L. sm The value of the first inductor L should not be too large. sm The inductance value can be set to satisfy the following formula 3:

[0058] L sm C sm ω2 2 <<1Formula 3

[0059] In one embodiment, if Figure 8 The second inductance and the second capacitance of the second filtering branch 122 are determined according to the second frequency value.

[0060] For example, the second inductor L T and the second capacitor C T It can be determined by the following formula 4:

[0061]

[0062] Wherein, ω2=2πf2, f2 is the doubled frequency, that is, the second frequency value.

[0063] In summary, the filter circuit 12 of the power unit 10 of the energy storage system 1 provided in this embodiment achieves filtering of harmonic components in the DC current of the energy storage circuit 11 through purely circuit means by setting the connection relationship between capacitors and resistors and setting the capacitance and resistance values. This has a relatively simple structure, thus reducing the cost of the power unit 10 and the energy storage system 1 in which it is located. Furthermore, since filtering is performed separately through two different filter branches, compared to providing a single filter branch in the filter circuit 12, the requirements for each capacitance and inductance value are reduced, and the internal space occupied by the capacitance and inductance in the filter circuit 12 in the power unit 10 and the entire energy storage system 1 is reduced, thereby improving the internal space utilization efficiency of the power unit 10 and the energy storage system 1.

[0064] Based on the filter circuit 12 provided in the present application, the power unit 10 in the energy storage system 1 can respectively filter out the first harmonic component and the second harmonic component in the DC current of the energy storage circuit 11. However, when the power of the energy storage system 1 changes, the voltage of the energy storage circuit 11 changes over a large range, etc., the filtering effect of the filter circuit 12 on the first harmonic component will be affected, and the performance requirement parameters of the first harmonic component cannot be met. Therefore, the present application also provides a control method for the power unit 10 of the energy storage system 1, which is used to improve the filtering effect of the filter circuit on the first filter component by adjusting the switching frequency of the voltage conversion circuit 13. The control method of the power unit 10 provided in the present application can be applied to the power unit 10 provided in the aforementioned embodiment of the present application and executed by the control circuit 130. The control method of the power unit 10 provided in the present application is introduced below in conjunction with the accompanying drawings.

[0065] Figure 9 This is a flow chart of an embodiment of a method for controlling a power unit provided in this application, as shown in FIG. Figure 9 The control method of the power unit 1 shown includes:

[0066] S101 : The control circuit 130 determines the real-time modulation ratio of the voltage conversion circuit 13 .

[0067] In one embodiment, the control circuit 130 executes the following steps at predetermined intervals: Figure 9 Alternatively, in another embodiment, when the control circuit 130 detects that the real-time modulation ratio changes and the range of the change is greater than the preset range, it executes the following steps: Figure 9 The method shown.

[0068] In one embodiment, the control circuit 130 may receive a real-time modulation ratio sent by other devices, or may calculate the real-time modulation ratio according to the operating parameters of the energy storage system 1 .

[0069] For example, the control circuit 130 may first calculate the peak value I of the phase current of the three-phase AC power provided by the grid 2 according to the following formulas 5 and 6: m .

[0070]

[0071] Among them, P s and Q s is the real-time active power and reactive power at the connection point between energy storage system 1 and grid 2, U sm It is the effective value of the line voltage of the AC bus at the grid connection point.

[0072] Subsequently, the control circuit 130 calculates the power factor at the outlet of the energy storage system 1 according to the following formulas 7, 8, and 9.

[0073]

[0074] Finally, the control circuit 130 calculates the real-time modulation ratio M according to the following formula 10.

[0075]

[0076] Among them, E bm is the DC voltage across the energy storage circuit 11, R dc is the internal resistance of the energy storage circuit 11 , and N is the number of power units 10 connected in series on the AC branch of the energy storage system 1 .

[0077] S102 : The control circuit 130 determines the current value and current ripple rate of the first harmonic component included in the DC current of the tank circuit 11 .

[0078] In one embodiment, the control circuit 130 first determines the current value of the first harmonic component on the voltage conversion circuit 13 side according to the following formula 11.

[0079]

[0080] Subsequently, the control circuit 130 determines the current value of the first harmonic component on the tank circuit 11 side according to the following formula 12 and formula 13.

[0081] R=(1+α)R dc Formula 12

[0082]

[0083] Here, α is a resistance enhancement coefficient, which is used to represent the influence of the second filtering branch 122 on the internal resistance of the energy storage circuit 11 and can usually be set to 10%.

[0084] Finally, the control circuit 130 determines the high-frequency current ripple rate of the first harmonic component of the energy storage circuit 11 according to the following formula 14.

[0085]

[0086] S103: When the current ripple rate γ determined in S102 b_ωh Greater than the preset threshold γ i_ωh When the voltage conversion circuit 13 is turned on and off, the control circuit 130 determines the switching frequency of the voltage conversion circuit 13 according to the real-time modulation ratio determined in S101, and controls the switch structure in the voltage conversion circuit 13 to be turned on and off at the adjusted switching frequency, thereby achieving the purpose of reducing the first harmonic component included in the DC current of the energy storage circuit 11.

[0087] In one embodiment, the control circuit 130 uses the following formula 15 according to the real-time modulation ratio M, L sm , the first capacitor C sm , the performance requirement parameter γ of the filter circuit 12 for the first harmonic component i_ωh , determine the switching frequency f c .

[0088]

[0089] It is understandable that when the current ripple rate determined in S102 is not greater than the preset threshold, the control circuit 130 does not adjust the switching frequency of the voltage conversion circuit 13 and continues to turn on and off the switch structure in the voltage conversion circuit 13 according to the current switching frequency value.

[0090] In summary, in the control method of the power unit 1 provided in this embodiment, by combining hardware circuits with software control, when the first harmonic component included in the current of the energy storage circuit 11 is greater than a preset threshold, the switching frequency of the voltage conversion circuit 13 is adjusted according to the current real-time modulation ratio of the voltage conversion circuit 13, thereby more quickly and effectively reducing the first harmonic component included in the DC current of the energy storage circuit 11, achieving the performance requirements of the energy storage system 1 within the full power operating range under different operating conditions, especially some extreme operating conditions such as power changes and voltage changes, and improving the stability of the energy storage system 1.

[0091] In the aforementioned embodiments of this application, the control method for controlling the power unit of the energy storage system provided in the embodiments of this application is described. In order to implement the various functions of the method provided in the above embodiments of this application, the control circuit 130, as the execution subject, may include a hardware structure and / or a software module, and implement the aforementioned functions in the form of a hardware structure, a software module, or a hardware structure and a software module. Whether a particular function is implemented in the form of a hardware structure, a software module, or a hardware structure and a software module depends on the specific application and design constraints of the technical solution.

[0092] It should be noted that it should be understood that the division of the various modules of the above device is merely a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated. Moreover, these modules can all be implemented in the form of software called by a processing element; or they can all be implemented in the form of hardware; or some modules can be implemented in the form of software called by a processing element, and some modules can be implemented in the form of hardware. For example, the processing module can be a separately established processing element, or it can be integrated into a chip of the above device. In addition, it can also be stored in the memory of the above device in the form of program code, and called by a processing element of the above device to perform the functions of the above-mentioned module. The implementation of other modules is similar. In addition, these modules can all or partly be integrated together, or they can be implemented independently. The processing element described here can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each of the above modules can be completed by an integrated logic circuit of hardware in the processor element or instructions in the form of software.

[0093] For example, the above modules may be one or more integrated circuits configured to implement the above methods, such as one or more application specific integrated circuits (ASICs), one or more digital signal processors (DSPs), or one or more field programmable gate arrays (FPGAs). For another example, when a module is implemented by scheduling program code on a processing element, the processing element may be a general-purpose processor, such as a central processing unit (CPU) or other processor that can call program code. For another example, these modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0094] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrations. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid state disk (SSD)).

[0095] For example, Figure 10 A schematic diagram of the structure of an electronic device provided in this application, such as Figure 10 The device shown can be used to execute the control method and / or steps in the control method provided in any embodiment of the present application. In one embodiment, Figure 10 The electronic device 2000 shown includes a processor 2001 and a memory 2002; wherein the memory 2002 is used to store computer-executable instructions, and the processor 2001 can execute the computer-executable instructions stored in the memory 2002. When the computer-executable instructions are executed by the processor 2001, the processor 2001 implements the method and / or steps thereof performed by any control circuit 130 in the aforementioned embodiments of the present application. In one embodiment, as Figure 10 The electronic device 2000 shown further includes a communication interface 2003, wherein the processor 2001 can communicate with other devices via the communication interface 2003.

[0096] The present application also provides a computer-readable storage medium, which stores computer-executable instructions. When the computer-executable instructions are executed, they can be used to implement any method and / or steps thereof performed by the control circuit 130 in any of the aforementioned embodiments of the present application.

[0097] An embodiment of the present application further provides a chip for executing instructions, wherein the chip is used to execute any of the methods and / or steps therein executed by the control circuit 130 as described above in the present application.

[0098] An embodiment of the present application further provides a computer program product, including a computer program, which, when executed, implements any of the methods and / or steps therein performed by the control circuit 130 as described above in the present application.

[0099] Those skilled in the art will appreciate that all or part of the steps in the above-described method embodiments can be implemented using hardware associated with program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A power unit of an energy storage system, characterized in that: include: a tank circuit (11) for storing electrical energy; A voltage conversion circuit (13) for converting the direct current of the energy storage circuit (11) into the alternating current of the power grid (2); A filter circuit (12) is provided between the energy storage circuit (11) and the voltage conversion circuit (13) and is used to filter out a first harmonic component generated by the voltage conversion circuit (13) and a second harmonic component generated by the alternating current of the power grid (2) included in the current of the energy storage circuit (11).

2. The power unit according to claim 1, characterized in that: The filtering circuit (12) comprises: A first filtering branch (121) is used to filter out a first harmonic component greater than the first frequency value generated by the voltage conversion circuit (13); The second filtering branch (122) is used for filtering out a second harmonic component generated by the alternating current of the power grid (2) and having a second frequency value equal to the second frequency value, wherein the second frequency value is less than the first frequency value.

3. The power unit according to claim 2, characterized in that: The first filtering branch (121) comprises: a first inductor and a first capacitor; The first end of the first inductor is connected to the first end of the energy storage circuit (11), the second end of the first inductor is connected to the first end of the first capacitor and the first end of the voltage conversion circuit (13), and the second end of the first capacitor is connected to the second end of the energy storage circuit (11) and the second end of the voltage conversion circuit (13).

4. The power unit according to claim 3, characterized in that: The first inductor and the first capacitor are determined based on a preset modulation ratio and a switching frequency of the voltage conversion circuit (13), and performance requirement parameters of the filter circuit (12) for the first harmonic component and the second harmonic component.

5. The power unit according to any one of claims 2 to 4, characterized in that: The second filtering branch (122) includes: a second inductor and a second capacitor; The first end of the second inductor is connected to the first end of the energy storage circuit (11), the second end of the second inductor is connected to the first end of the second capacitor, and the second end of the second capacitor is connected to the second end of the energy storage circuit (11) and the second end of the voltage conversion circuit (13).

6. The power unit according to claim 5, characterized in that: The second inductance and the second capacitance are determined according to the second frequency value.

7. The power unit according to any one of claims 1 to 6, characterized in that: The voltage conversion circuit (13) comprises an H-bridge circuit.

8. An energy storage system, characterized in that: include: A first AC branch, comprising a first AC inductor and a plurality of power units according to any one of claims 1 to 7 connected in series; A second AC branch comprising a second AC inductor and a plurality of power units according to any one of claims 1 to 7 connected in series; The third AC branch comprises a third AC inductor and a plurality of power units according to any one of claims 1 to 7 connected in series.

9. A method for controlling a power unit, characterized in that: For controlling the power unit according to any one of claims 1 to 7, the control method comprises: determining a real-time modulation ratio of the voltage conversion circuit (13); determining a current value and a current ripple rate of the first harmonic component; When the current ripple rate is greater than a preset threshold, the switching frequency of the voltage conversion circuit (13) is adjusted according to the real-time modulation ratio to reduce the first harmonic component generated by the voltage conversion circuit (13) and included in the current of the energy storage circuit (11).

10. The method according to claim 9, characterized in that The adjusting the switching frequency of the switch structure in the voltage conversion circuit (13) comprises: The switching frequency is determined according to the real-time modulation ratio, the first inductor, the first capacitor, and performance requirement parameters of the filter circuit (12) for the first harmonic component.

11. The method according to claim 9 or 10, characterized in that The determining of the current value and current ripple rate of the first harmonic component includes: The current value and current ripple rate of the first harmonic component are determined according to the real-time modulation ratio, the first inductor, the first capacitor and the switching frequency of the voltage conversion circuit (13).

12. The method according to any one of claims 9 to 11, characterized in that: Determining the real-time modulation ratio of the voltage conversion circuit (13) comprises: The real-time modulation ratio is determined according to the effective value of the voltage at the grid connection point, the voltage value of the energy storage circuit (11), the internal resistance value of the energy storage circuit (11), and the number of power units (10) connected in series on the AC branch of the energy storage system 1.

13. An electronic device, characterized in that: include: memory and processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory, so that the processor performs the method according to any one of claims 9 to 12.

14. A computer-readable storage medium, characterized in that Computer-executable instructions are stored, and when the computer-executable instructions are executed, the method according to any one of claims 9 to 12 is implemented.

15. A computer program product, characterized in that The method comprises a computer program, which implements the method according to any one of claims 9 to 12 when the computer program is executed.

Images