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

Abstract

The present application provides an energy storage system, a power unit, a control method, a device, a medium, and a product. The power unit comprises an energy storage circuit, a filter circuit, and a voltage conversion circuit. The filter circuit can simultaneously implement the following in a direct current in the energy storage circuit: a high-frequency component that is greater than a first frequency value and that is caused by a switching frequency of the voltage conversion circuit is filtered out, and a frequency-doubled component that is equal to a second frequency value and that is caused by an alternating current of a power grid is filtered out. Therefore, a harmonic component in the direct current of the energy storage circuit is reduced, thereby reducing a loss caused by the harmonic component to the energy storage circuit, and ensuring continuous and stable operation of the entire energy storage system.

Description

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

[0001] The present application claims priority to the Chinese patent application No. 202411395985.2, filed on September 30, 2024, entitled "Energy storage system, power unit, control method, device, medium and product", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of energy storage, in particular to an energy storage system, a power unit, a control method, a device, a medium and a product. BACKGROUND

[0003] A new power system generates electric energy by new power generation devices such as wind power and photovoltaic, and transmits the electric energy to loads through a power grid. Since the electric energy generated by these power generation devices has fluctuation and randomness in time, an energy storage system is also provided in the power system. The energy storage system is connected to the power grid and can be used to store electric energy when the power generation devices generate more electric energy, and supply electric energy to the power grid when the power generation devices generate less electric energy, so as to ensure the continuous and stable operation of the loads and realize more flexible control and distribution of electric energy.

[0004] However, after the energy storage system is connected to the power grid, there are many harmonic components in the direct current of the energy storage circuit. When the harmonic components enter the energy storage circuit, the loss of the energy storage circuit will be faster, thereby affecting the normal operation of the entire energy storage system. How to more effectively filter out the harmonic components in the direct current is a technical problem to be solved in the field. SUMMARY

[0005] 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 the harmonic components in the direct current of the energy storage circuit.

[0006] The first aspect of the present application provides a power unit of an energy storage system, comprising an energy storage circuit, a voltage conversion circuit and a filter circuit. The energy storage circuit is used to store electric energy; the voltage conversion circuit is used to convert the direct current of the energy storage circuit and the alternating current of the power grid; the filter circuit is arranged between the energy storage circuit and the voltage conversion circuit, and is used to filter out the first harmonic components generated by the voltage conversion circuit and the second harmonic components generated by the alternating current of the power grid included in the current of the energy storage circuit.

[0007] The second aspect of the present application provides an energy storage system, comprising: a first alternating current branch comprising a first alternating current inductor and a plurality of power units as described in the first aspect of the present application connected in series; a second alternating current branch comprising a second alternating current inductor and a plurality of power units as described in the first aspect of the present application connected in series; and a third alternating current branch comprising a third alternating current inductor and a plurality of power units as described in the first aspect of the present application connected in series.

[0008] The third aspect of the present application provides a control method of a power unit, used for controlling the power unit provided in the first aspect of the present application, the control method comprising: determining a real-time modulation ratio of the voltage conversion circuit; determining a current value and a current ripple of the first harmonic component; and when the current ripple is greater than a preset threshold, adjusting a switching frequency of the voltage conversion circuit according to the real-time modulation ratio, so as to reduce the first harmonic component generated by the voltage conversion circuit and included in the current of the energy storage circuit.

[0009] The fourth aspect of the present application provides an electronic device, comprising: a memory and a processor; the memory stores computer executable instructions; and 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.

[0010] The fifth aspect of the present application provides a computer readable storage medium, storing computer executable instructions, the computer executable instructions being executed to implement the method described in the third aspect of the present application.

[0011] The sixth aspect of the present application provides a computer program product, comprising a computer program, the computer program being executed to implement the method described in the third aspect of the present application.

[0012] In summary, the energy storage system, the power unit, the control method, the device, the medium and the product provided by the present application can filter out the high-frequency component greater than the first frequency value caused by the switching frequency of the voltage conversion circuit and the double-frequency component equal to the second frequency value caused by the alternating current of the power grid at the same time through the filter circuit, thereby reducing the harmonic component in the direct current of the energy storage circuit, reducing the loss caused by the harmonic component to the energy storage circuit, and ensuring the continuous and stable operation of the entire energy storage system. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0014] Fig. 1 is a schematic diagram of an application scenario of the present application;

[0015] Fig. 2 is a structural schematic diagram of an embodiment of an energy storage system provided by the present application;

[0016] Fig. 3 is a structural schematic diagram of a power unit in the prior art;

[0017] Fig. 4 is a schematic diagram of current variation of an energy storage circuit in the prior art;

[0018] Fig. 5 is a structural schematic diagram of a power unit of an energy storage system provided by the present application;

[0019] Fig. 6 is a schematic diagram of current variation of an energy storage circuit provided by the present application;

[0020] Fig. 7 is a structural schematic diagram of another embodiment of a power unit of an energy storage system provided by the present application;

[0021] Fig. 8 is a circuit structural schematic diagram of an embodiment of a power unit provided by the present application;

[0022] Fig. 9 is a flow schematic diagram of an embodiment of a control method of a power unit provided by the present application;

[0023] Fig. 10 is a structural schematic diagram of an electronic device provided by the present application. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0025] The terms "first", "second", "third", "fourth" and the like (if any) in the specification and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to include those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, product or device.

[0026] Fig. 1 is a schematic diagram of an application scenario of the present application, as shown in Fig. 1, a new power system mainly composed of new energy. In which, the power generation device 3 can be a wind power generation device or a photovoltaic power generation device, etc., the power generated by the power generation device 3 is provided to the load 4 through the power grid 2. Due to the fluctuation and randomness of the power generated by the power generation device 3 in time, some power systems also have a storage system 1, and the storage system 1 is connected to the power grid 2. The storage system 1 can store the excess power when the power generated by the power generation device 3 is more, and when the power generated by the power generation device 3 is less due to environmental factors, the storage system 1 can provide power to the load 4 through the power grid 2, thereby ensuring the continuous and stable operation of the load 4, and realizing more flexible control and distribution of the power generated by the power generation device 3.

[0027] Fig. 2 is a schematic diagram of an embodiment of the storage system provided by the present application, as shown in Fig. 2, the specific structure of the power grid 2 and the storage system 1 in Fig. 1 is shown, in which the power grid 2 supports three-phase alternating current, and the three-phase alternating current of the power grid 2 corresponds to three interfaces Ua, Ub and Uc in turn.

[0028] As shown in Fig. 2, the storage system 1 includes a first AC branch, a second AC branch and a third AC branch connected to the three interfaces of the three-phase alternating current of the power grid 2 respectively, and the other ends of the first AC branch, the second AC branch and the third AC branch are also connected together. In which, the first AC branch includes a first AC inductor L1 and a plurality of power units 10, taking n power units 10 as an example, denoted as SM11, SM12, …, SM1n. The second AC branch includes a second AC inductor L2 and a plurality of power units 10, also taking n power units 10 as an example, denoted as SM21, SM22, …, SM2n. The third AC branch includes a third AC inductor L3 and a plurality of power units 10, also taking n power units 10 as an example, denoted as SM31, SM32, …, SM3n.

[0029] Fig. 3 is a schematic diagram of a power unit in the prior art, as shown in Fig. 3, the power unit can be applied to the storage system shown in Fig. 2. As shown in Fig. 3, the power unit 10 includes a storage circuit 11 and a voltage conversion circuit 13, in which the storage circuit 11 can be a battery or the like for storing power. The voltage conversion circuit 13 is used to convert the direct current supported by the storage circuit 11 and the alternating current supported by the power grid side, for example, to convert the voltage Udc of the direct current into the voltage Uo of the alternating current. In some technologies, the voltage conversion circuit 13 can be realized by a power conversion system (PCS), and the PCS also includes other circuits which are not shown in the figure.

[0030] When the power unit 10 shown in FIG. 3 is in operation, in addition to the direct current existing in the side where the voltage conversion circuit 13 is connected with the energy storage circuit 11, there are also double-frequency currents caused by the alternating current of the power grid 2 and high-order harmonic currents caused by the switching frequency of the voltage conversion circuit 13, which can cause the current flowing through the energy storage circuit 11 to change. The change here includes the change of the input current when the energy storage circuit 11 is charging and the change of the output current when the energy storage circuit 11 is discharging.

[0031] For example, FIG. 4 is a schematic diagram of the current change of the energy storage circuit in the prior art, where the ideal current inputted or outputted by the energy storage circuit 11 is id, and the actual current inputted or outputted by the energy storage circuit 11 under the influence of the double-frequency current and the high-order harmonic current is idcs. When the harmonic component in the actual current of the energy storage circuit 11 directly flows into the energy storage circuit 11, it can cause the energy storage circuit 11 to have a loss and cause the temperature of the energy storage circuit 11 to rise, which can reduce the service life and safety of the energy storage circuit 11 and affect the normal operation of the entire energy storage system. Therefore, how to effectively filter the harmonic component in the direct current of the energy storage circuit 11 in the power unit 10 of the energy storage system 1 is a technical problem to be solved in the field.

[0032] The technical solutions of the present application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes can not be described in detail in some embodiments.

[0033] FIG. 5 is a schematic diagram of the structure of a power unit of an energy storage system provided by the present application. The power unit 10 shown in FIG. 5 can be applied to the scenarios shown in FIG. 1 and FIG. 2. Specifically, the power unit 10 shown in FIG. 5 includes an energy storage circuit 11, a filter circuit 12 and a voltage conversion circuit 13.

[0034] The energy storage circuit 11 is used to store electrical energy, and the energy storage circuit 11 can be a battery pack or the like.

[0035] The voltage conversion circuit 13 is used to convert the direct current supported by the energy storage circuit 11 and the alternating current supported by the power grid side. For example, when the energy storage circuit 11 is charging, the voltage conversion circuit 13 is used to convert the alternating current into direct current; when the energy storage circuit 11 is discharging, the voltage conversion circuit 13 is used to convert the direct current into alternating current.

[0036] The filter circuit 12 is arranged between the energy storage circuit 11 and the voltage conversion circuit 13, that is, the energy storage circuit 11 is connected with the voltage conversion circuit 13 through the filter circuit 12.

[0037] In an embodiment, the filter circuit 12 is specifically a passive filter circuit.

[0038] The filter circuit 12 provided by the embodiments of the present application can be used to filter the harmonic components of the direct current of the energy storage circuit 11. Specifically, the harmonic components filtered by the filter circuit 12 include the first harmonic components generated by the voltage conversion circuit 13 and the second harmonic components generated by the alternating current of the power grid 2.

[0039] Specifically, the first harmonic components refer to high-frequency harmonic currents greater than a first frequency value, and the second harmonic components refer to double-frequency currents with a frequency value equal to twice a second frequency value, wherein the second frequency value is less than the first frequency value.

[0040] For example, the filter circuit 12 can filter the first harmonic components greater than the first frequency value in the direct current of the energy storage circuit 11 by low-pass filtering.

[0041] Meanwhile, the filter circuit 12 can also filter the second harmonic components of the specified second frequency value.

[0042] In an embodiment, the second harmonic components can be double-frequency currents included in the direct 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 can be 100 Hz.

[0043] FIG. 6 is a schematic diagram of the current change of the energy storage circuit provided by the present application, wherein the direct current idcs of the energy storage circuit 11 includes the first harmonic components greater than the first frequency value and the second harmonic components equal to the second frequency value. After the direct current idcs of the energy storage circuit 11 is processed by the filter circuit 12, the first harmonic components and the second harmonic components in the direct current idcs of the energy storage circuit 11 are filtered, and the direct current idc output by the filter circuit 12 is more smooth in the time domain waveform compared with the direct current idcs before filtering, and is closer to the ideal direct current id of the energy storage circuit 11.

[0044] In summary, the power unit 10 of the energy storage system 1 provided in this embodiment can simultaneously remove the high-frequency component greater than the first frequency value in the direct current of the energy storage circuit 11 and remove the double-frequency component equal to the second frequency value in the direct current of the energy storage circuit 11 through the filter circuit 12, thereby reducing the harmonic component in the direct current of the energy storage circuit 11, reducing the loss caused by the harmonic component flowing into the energy storage circuit 11, avoiding the temperature rise of the energy storage circuit 11 caused by the harmonic component, and further guaranteeing 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 realizes the removal of two harmonic components through one circuit, reduces the structural complexity of the filter circuit 12, does not introduce other interference sources to the power unit 10, and is more conducive to the application and promotion of the power unit 10 and the energy storage system in which the power unit 10 is located.

[0045] FIG. 7 is a structural schematic diagram of another embodiment of the power unit of the energy storage system provided in this application. As shown in FIG. 7, the power unit 10 is based on the power unit 10 shown in FIG. 5, and 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 respectively connected between the energy storage circuit 11 and the voltage conversion circuit 13.

[0046] The first filter branch 121 is used to remove the first harmonic component with a frequency value greater than the first frequency value in the direct current of the energy storage circuit 11. The first filter branch 121 can also be referred to as a low-pass filter branch.

[0047] The second filter branch 122 is used to remove the second harmonic component with a frequency value equal to the second frequency value in the direct current of the energy storage circuit 11. The second filter branch 122 can also be referred to as a single-tuned filter branch.

[0048] In summary, the power unit provided in this embodiment realizes the removal of the first harmonic component and the second harmonic component in the direct current of the energy storage circuit 11 through the two filter branches, so that the processing of removing the two harmonic components can be simultaneously and in parallel, thereby improving the filtering efficiency of the filter circuit on the harmonic component.

[0049] FIG. 8 is a circuit structural schematic diagram of an embodiment of the power unit provided in this application. As shown in FIG. 8, a specific circuit implementation of the power unit 10 shown in FIG. 7 is shown.

[0050] As shown in FIG. 8, the first filter branch 121 includes: a first inductor L sm and a first capacitor C sm , wherein a first end of the first inductor L sm is connected to a first end of the energy storage circuit 11, and a first end of the first capacitor C smthe first end of the first capacitor C sm the first end of the first capacitor C sm the second end of the first capacitor C

[0051] The second filter branch 122 comprises: a second inductor L T and a second capacitor C T , wherein the second inductor L T the first end of the first capacitor C T the second end of the first capacitor C T the first end of the first capacitor C T the second end of the first capacitor C

[0052] It can be seen that the first filter branch 121 comprises a first inductor L sm and a first capacitor C sm connected in series, constituting a low-pass filter, which can be used to filter out high-frequency ripple current and part of the double-frequency ripple current generated by the voltage conversion circuit 13. The second filter branch 122 comprises a second inductor L T and a second capacitor C T connected in series, constituting an LC series resonance circuit, which can be used to filter out the double-frequency ripple current. At the same time, the second filter branch 122 and the first capacitor C sm are connected in parallel. In addition, Rdc is the internal resistance of the energy storage circuit 11.

[0053] In this embodiment, the voltage conversion circuit 13 is an H-bridge circuit. The H-bridge circuit comprises four parallel switch structures a, b, c and d, each of which can be a triode, an Insulate-Gate Bipolar Transistor (IGBT) or the like. The control circuit 130 of the voltage conversion circuit 13 controls each of the switch structures a-d in the H-bridge circuit to turn on and off according to a switching frequency. The process of turning on and off the switch structures a-d according to the switching frequency will result in the existence of a double-frequency component in the direct current of the energy storage circuit 11.

[0054] In one embodiment, the first inductor and the first capacitor of the first filter branch 121 shown in FIG. 8 are determined according to the preset modulation ratio of the voltage conversion circuit 13, the switching frequency, the performance requirement parameter of the first harmonic component of the filter circuit 12 and the performance requirement parameter of the second harmonic component.

[0055] For example, the first inductor L sm and the first capacitor C sm are determined by the following formula one and formula two:

[0056] wherein M is a preset modulation ratio of the voltage conversion circuit 13. m is a current peak value of the phase current of the power grid 2. dc is a H-bridge DC voltage of the voltage conversion circuit 13. h = 4πf c , f c is a switching frequency of the switching structure a-d in the voltage conversion circuit 13. i_ωh is a performance requirement parameter of the filter circuit 12 for components greater than the first frequency value, γ u_ω2 is a performance requirement parameter of the filter circuit 12 for components of the second frequency value. Wherein γ i_ωh and γ u_ω2 are usually set as a constant not more than 1%.

[0057] In addition, since the first inductor L sm is connected in series between the second filter branch 122 and the first capacitor C sm , although the oscillation of the DC current generated at the double frequency can be effectively avoided, a large amount of double frequency current will flow through the first inductor L sm . Therefore, the value of the first inductor L sm should not be too large, and the inductance value of the first inductor L sm may be set to satisfy the following formula three: L sm C sm ω2 2 <<1 Formula three

[0058] In an embodiment, the second inductor and the second capacitor of the second filter branch 122 shown in FIG. 8 are determined according to the second frequency value.

[0059] For example, the second inductor L T and the second capacitor C T may be determined by the following formula four:

[0060] wherein ω2=2πf2, f2 is a double frequency frequency, i.e. the second frequency value.

[0061] In conclusion, the filter circuit 12 of the power unit 10 of the energy storage system 1 provided in the embodiment is connected by capacitors and resistors, and the values of the capacitors and the resistors are set, so that the harmonic components in the direct current of the energy storage circuit 11 are filtered out in a pure circuit manner, and the structure is relatively simple, and thus the cost of the power unit 10 and the energy storage system 1 can be reduced. Meanwhile, since the filtering is performed by two different filtering branches, compared with the case that one filtering branch is arranged in the filter circuit 12, the requirements for the values of each capacitor and inductor are reduced, and the occupation of the capacitors and inductors in the filter circuit 12 to the internal space of the power unit 10 and the entire energy storage system 1 is reduced, so that the internal space utilization efficiency of the power unit 10 and the energy storage system 1 is improved.

[0062] Based on the filter circuit 12 provided in the application, the power unit 10 in the energy storage system 1 can filter out the first harmonic component and the second harmonic component in the direct current of the energy storage circuit 11, respectively. However, in the case that the power of the energy storage system 1 changes, the voltage of the energy storage circuit 11 changes greatly, or the like, the filtering effect of the filter circuit 12 on the first harmonic component is affected, and the performance requirement parameter of the first harmonic component cannot be met. Therefore, the application further provides a control method of 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 harmonic component by adjusting the switching frequency of the voltage conversion circuit 13. The control method of the power unit 10 provided in the application can be applied to the power unit 10 provided in the foregoing embodiments of the application and is executed by the control circuit 130. The control method of the power unit 10 provided in the application will be introduced below with reference to the accompanying drawings.

[0063] FIG. 9 is a flowchart of an embodiment of the control method of the power unit provided in the application. As shown in FIG. 9, the control method of the power unit 1 includes the following steps.

[0064] S101: The control circuit 130 determines the real-time modulation ratio of the voltage conversion circuit 13.

[0065] In an embodiment, the control circuit 130 executes the method shown in FIG. 9 every predetermined time interval, and first acquires the real-time modulation ratio of the voltage conversion circuit 13. Alternatively, in another embodiment, the control circuit 130 executes the method shown in FIG. 9 when it is detected that the real-time modulation ratio changes and the change range is greater than a preset range.

[0066] In an embodiment, the control circuit 130 can receive the real-time modulation ratio sent by other devices, or can also calculate the real-time modulation ratio according to the working parameters of the energy storage system 1.

[0067] For example, the control circuit 130 can first calculate the peak value I of the phase current of the three-phase alternating current provided by the power grid 2 according to the following formulas five and six.m .

[0068] wherein P s and Q s are the real-time active power and reactive power at the grid-connection point of the energy storage system 1 and the power grid 2, U sm is the effective value of the line voltage of the AC bus at the grid-connection point.

[0069] Subsequently, the control circuit 130 calculates the power factor at the outlet of the energy storage system 1 according to the following Formula Seven, Formula Eight and Formula Nine.

[0070] Finally, the control circuit 130 calculates the real-time modulation ratio M according to the following Formula Ten.

[0071] wherein E bm is the voltage value of the DC voltage across the energy storage circuit 11, R dc is the internal resistance value 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.

[0072] S102: The control circuit 130 determines the current value of the first harmonic component included in the DC current of the energy storage circuit 11 and the current ripple ratio.

[0073] In an embodiment, the control circuit 130 first determines the current value of the first harmonic component on the side of the voltage conversion circuit 13 according to the following Formula Eleven.

[0074] Subsequently, the control circuit 130 determines the current value of the first harmonic component on the side of the energy storage circuit 11 according to the following Formula Twelve and Formula Thirteen. R = (1 + a)R dc Formula Twelve

[0075] wherein a is a resistance enhancement coefficient for indicating the influence of the second filter branch 122 on the internal resistance of the energy storage circuit 11, and can be set to 10% in general.

[0076] Finally, the control circuit 130 determines the high-frequency current ripple ratio of the first harmonic component of the energy storage circuit 11 according to the following Formula Fourteen.

[0077] S103: When the current ripple ratio g b_ωh determined in S102 is greater than a preset threshold g i_ωhWhen the current ripple ratio 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 control the switch structure in the voltage conversion circuit 13 to turn on and off according to the current switching frequency value.

[0078] In an embodiment, the control circuit 130 determines the switching frequency f of the voltage conversion circuit 13 according to the real-time modulation ratio M, L sm , the first capacitance C sm , the performance requirement parameter γ of the first harmonic component of the filter circuit 12 i_ωh by the following formula fifteen. c

[0079] It can be understood that when the current ripple ratio 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 control the switch structure in the voltage conversion circuit 13 to turn on and off according to the current switching frequency value.

[0080] In summary, in the control method of the power unit 1 provided in the embodiment, by combining hardware circuit and software control, when the first harmonic component included in the current of the energy storage circuit 11 is greater than the preset threshold, the switching frequency of the voltage conversion circuit 13 is adjusted according to the real-time modulation ratio of the current voltage conversion circuit 13, so that the first harmonic component included in the direct current of the energy storage circuit 11 is more quickly and effectively reduced, and the performance requirements of the energy storage system 1 in different operating conditions, especially in some extreme operating conditions such as power change and voltage change, are realized, and the stability of the energy storage system 1 is improved.

[0081] In the foregoing embodiments of the present application, the control method for controlling the power unit of the energy storage system provided by the embodiments of the present application is introduced, and in order to realize the functions in the above-mentioned method provided by the embodiments of the present application, the control circuit 130 as the execution subject can include hardware structure and / or software module, and the above-mentioned functions are realized in the form of hardware structure, software module, or hardware structure plus software module. Whether a certain function in the above-mentioned functions is executed in the form of hardware structure, software module, or hardware structure plus software module depends on the specific application and design constraints of the technical solution.

[0082] ​It should be noted that the division of the various modules of the above apparatus is only a logical functional division, and all or part of them can be integrated into one physical entity or physically separated in actual implementation. These modules can all be implemented in the form of software invoked by a processing element; all in the form of hardware; or some modules are implemented in the form of software invoked by a processing element, and some modules are implemented in the form of hardware. For example, the processing module can be a separately established processing element, or can be integrated in a chip of the above apparatus, in addition, it can also be stored in the form of program code in the memory of the above apparatus, and the function of the above determination module is called and executed by a processing element of the above apparatus. The implementation of other modules is similar. In addition, all or part of these modules can be integrated together or independently implemented. The processing element here can be an integrated circuit with signal processing capability. In the implementation process, each step of the above method or each module can be completed by the integrated logic circuit of the hardware in the processor element or the instruction in the form of software.

[0083] For example, the above modules can be one or more integrated circuits configured to implement the above method, such as one or more application specific integrated circuits (ASICs), or one or more digital signal processors (DSPs), or one or more field programmable gate arrays (FPGAs), etc. For another example, when a certain module above is implemented in the form of program code invoked by a processing element, the processing element can be a general purpose processor, such as a central processing unit (CPU) or other processor that can invoke program code. For another example, these modules can be integrated together to implement in the form of system on a chip (SOC).

[0084] In the above embodiments, all or part of the embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments can be implemented 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, all or part of the processes or functions according to the embodiments of the present application are generated. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable devices. 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 through wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) mode. The computer readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. containing one or more available media. The available media can be magnetic media (such as floppy disk, hard disk, magnetic tape), optical media (such as DVD), or semiconductor media (such as solid state disk (SSD)) and the like.

[0085] For example, FIG. 10 is a structural schematic diagram of an electronic device provided by the present application. The device shown in FIG. 10 can be used to execute the control method and / or steps in the control method provided by any of the embodiments of the present application. In an embodiment, the electronic device 2000 shown in FIG. 10 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 therein executed by the control circuit 130 in any of the preceding embodiments of the present application. In an embodiment, the electronic device 2000 shown in FIG. 10 further includes a communication interface 2003, wherein the processor 2001 can communicate with other devices through the communication interface 2003

[0086] The present application also provides a computer readable storage medium, which stores computer executable instructions, and the computer executable instructions, when executed, can be used to implement the method and / or steps therein executed by the control circuit 130 in any of the preceding embodiments of the present application.

[0087] The embodiments of the present application also provide a chip for executing instructions, which is used to execute the method and / or steps therein executed by the control circuit 130 in any of the preceding embodiments of the present application.

[0088] The embodiments of the present application further provide a computer program product, comprising a computer program which, when executed, implements the method performed by the control circuit 130 and / or the steps therein of any of the preceding embodiments of the present application.

[0089] Those skilled in the art can understand that all or part of the steps of the foregoing method embodiments can be completed by relevant hardware of program instructions. The foregoing program can be stored in a computer readable storage medium. When the program is executed, the steps of the foregoing method embodiments are executed; and the foregoing storage medium includes various media capable of storing program codes, such as ROM, RAM, magnetic disk, or optical disk.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate 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 by, The power unit comprises: a storage circuit (11) for storing electric energy; a voltage conversion circuit (13) for converting direct current of the storage circuit (11) and alternating current of a power grid (2) to each other; a filter circuit (12) arranged between the storage circuit (11) and the voltage conversion circuit (13) and used for filtering out first harmonic components generated by the voltage conversion circuit (13) and second harmonic components generated by the alternating current of the power grid (2) included in current of the storage circuit (11).

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

3. The power unit of claim 2, wherein, The first filter branch (121) comprises: a first inductor and a first capacitor; 4. The power unit of claim 3, wherein, a first end of the first inductor is connected to a first end of the storage circuit (11), a second end of the first inductor is connected to a first end of the first capacitor and a first end of the voltage conversion circuit (13), and a second end of the first capacitor is connected to a second end of the storage circuit (11) and a second end of the voltage conversion circuit (13).

5. The power unit according to any of claims 2-4, characterized in that, The first inductor and the first capacitor are determined according to a preset modulation ratio and a switching frequency of the voltage conversion circuit (13), a performance requirement parameter of the filter circuit (12) for the first harmonic components and a performance requirement parameter of the filter circuit (12) for the second harmonic components. The second filter branch (122) comprises:

6. The power unit of claim 5, wherein, a second inductor and a second capacitor; 7. The power unit according to any of claims 1-6, characterized in that, a first end of the second inductor is connected to the first end of the storage circuit (11), a second end of the second inductor is connected to a first end of the second capacitor, and a second end of the second capacitor is connected to the second end of the storage circuit (11) and the second end of the voltage conversion circuit (13).

8. An energy storage system characterized by, The second inductor and the second capacitor are determined according to the second frequency value. The voltage conversion circuit (13) comprises: an H-bridge circuit. The power unit comprises:

9. A control method of a power unit, characterized by, a first alternating current branch comprising a first alternating current inductor and a plurality of power units according to any one of claims 1-7 connected in series; a second alternating current branch comprising a second alternating current inductor and a plurality of power units according to any one of claims 1-7 connected in series; a third alternating current branch comprising a third alternating current inductor and a plurality of power units according to any one of claims 1-7 connected in series. The control method for controlling the power unit according to any one of claims 1-7 comprises:

10. The method of claim 9, wherein, determining a real-time modulation ratio of the voltage conversion circuit (13); determining a current value and a current ripple of the first harmonic components; when the current ripple is greater than a preset threshold, adjusting a switching frequency of the voltage conversion circuit (13) according to the real-time modulation ratio to reduce the first harmonic components generated by the voltage conversion circuit (13) included in the current of the storage circuit (11). The adjusting the switching frequency of the voltage conversion circuit (13) comprises: The switching frequency is determined according to the real-time modulation ratio, the first inductance, the first capacitance, and a performance requirement parameter of the first harmonic component of the filter circuit (12).

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

12. The method according to any one of claims 9-11, characterized in that, The real-time modulation ratio of the voltage conversion circuit (13) is determined according to the effective value of the grid-connected voltage, 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). The method comprises:

13. 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 according to any one of claims 9-12. The computer executable instructions are stored in the memory, and the computer executable instructions are executed to implement the method according to any one of claims 9-12.

14. A computer-readable storage medium, characterized in that, The computer program is executed to implement the method according to any one of claims 9-12.

15. A computer program product, characterised in that, ​

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