Energy storage system, filter parameter acquisition method and device and electronic equipment

Abstract

The invention relates to an energy storage system, a filter parameter acquisition method and device and electronic equipment, and belongs to the field of power systems. The method comprises the following steps: acquiring relevant parameters of the energy storage system, wherein the relevant parameters comprise the working frequency of a power grid connected with the energy storage system, the current amplitude of the power grid, the modulation ratio of the power grid, and the voltage, the current pulsation rate and the voltage pulsation rate of sub modules in the energy storage system; and determining the filter parameters in the correlation according to the correlation parameters and the correlation between the filter parameters in the sub-modules and the correlation parameters. The pulsating current in the energy storage system is suppressed by adopting a passive method of the passive filter, the pulsating current is suppressed by arranging the LC filters in the sub-modules, and the parameters of the LC filter in each sub-module are determined according to the related parameters of the energy storage system and the correlation between the filter parameters and the related parameters, so that the pulsating current in the energy storage system is suppressed. Therefore, accurate passive filter parameters can be obtained, and the pulsating current in the current energy storage system can be accurately suppressed.

Description

Technical Field

[0001] The present application belongs to the field of power systems, and specifically relates to an energy storage system, a filter parameter acquisition method, a device and an electronic device. Background Art

[0002] With the development of the power system, modular multi-level energy storage systems have gradually entered the demonstration application stage. The modular multi-level energy storage system includes multiple sub-modules, each of which can be connected in series and / or in parallel. The sub-modules generally integrate power electronic components such as electrochemical devices. In the AC system, each sub-module has the inherent problem of power pulsation of a single-phase inverter. Power pulsation can cause pulsating current in the charge and discharge current of the electrochemical device. Due to the large amplitude of the pulsating current, the current peak of the electrochemical device will exceed the rated current of the electrochemical device, thereby reducing the service life of the electrochemical device. Summary of the invention

[0003] In view of this, the purpose of the present application is to provide an energy storage system, a filter parameter acquisition method, a device and an electronic device to improve the problem in the related art that the pulsating current in the current energy storage system cannot be accurately suppressed, thereby reducing the service life of the electrochemical device.

[0004] The embodiment of the present application is implemented as follows:

[0005] In a first aspect, an embodiment of the present application provides an energy storage system, comprising: a submodule, wherein the submodule comprises: an LC filter and an electrochemical device, wherein the electrochemical device is connected in parallel with the filter capacitor in the LC filter and in series with the filter inductor in the LC filter, and the filter inductor is located between the electrochemical device and the filter capacitor; wherein the parameters of the LC filter are determined according to relevant parameters of the energy storage system and the correlation between the filter parameters and the relevant parameters, wherein the relevant parameters include the operating frequency of the power grid to which the energy storage system is connected, the current amplitude of the power grid, the modulation ratio of the power grid, the voltage, current pulsation rate, and voltage pulsation rate of the submodule; wherein the correlation is determined according to an AC / DC network, wherein the AC / DC network is an equivalent circuit of a DC side circuit connected to a half-bridge circuit in the submodule, and when equivalent, the current flowing through the DC side circuit is equivalent to the superposition of a DC current, a base frequency AC, and a double frequency AC.

[0006] The present application adopts a passive method of a passive LC filter to suppress the pulsating current in the energy storage system, and suppresses the pulsating current by setting an LC filter in the submodule. At the same time, the parameters of the LC filter in each submodule in the present application are determined according to the above-mentioned relevant parameters of the energy storage system and the correlation between the filter parameters and the relevant parameters, and the correlation is determined according to the equivalent AC-DC network of the DC side circuit connected to the half-bridge circuit in the submodule, and when equivalent, the current flowing through the DC side circuit is equivalent to the superposition of DC current, base frequency AC and double frequency AC, so that accurate passive filter parameters can be obtained, and then the pulsating current in the current energy storage system can be accurately suppressed, and then the problem of shortened service life of the electrochemical device due to the influence of pulsating current can be improved.

[0007] In combination with a possible implementation manner of the embodiment of the first aspect, the related parameters also include: the internal resistance of the electrochemical device.

[0008] In the embodiment of the present application, when designing the filter parameters in the submodule, the internal resistance of the electrochemical device is also taken into account, so that the designed filter parameters are more accurate and can better suppress the pulsating current in the current energy storage system.

[0009] In combination with a possible implementation manner of the embodiment of the first aspect, the correlation includes: a first correlation between the filter parameter and a first related parameter, and a second correlation between the filter parameter and a second related parameter, wherein the first correlation is determined according to the DC network, the baseband AC network and the doubled frequency AC network decomposed from the AC / DC network; the second correlation is determined according to the baseband AC network and the doubled frequency AC network; the parameters of the LC filter are obtained according to the first equation and the second equation, wherein the first equation is obtained according to the first related parameter in the related parameters and the first correlation, and the second equation is obtained according to the second related parameter in the related parameters and the second correlation; wherein the first related parameters include: the operating frequency of the power grid, the current pulsation rate, and the internal resistance of the electrochemical device; wherein the second related parameters include: the operating frequency of the power grid, the current amplitude of the power grid, the modulation ratio of the power grid, the internal resistance of the electrochemical device, the voltage pulsation rate, and the voltage.

[0010] In the embodiment of the present application, it is only necessary to substitute the first related parameter into the first related relationship to obtain the first equation, and substitute the second related parameter into the second related relationship to obtain the second equation. By solving the first equation and the second equation, the parameters of the LC filter can be obtained quickly and accurately.

[0011] In a second aspect, an embodiment of the present application further provides a filter parameter acquisition method, comprising:

[0012] Obtain relevant parameters of the energy storage system, the relevant parameters including: the operating frequency of the power grid to which the energy storage system is connected, the current amplitude of the power grid, the modulation ratio of the power grid, the voltage, current pulsation rate, and voltage pulsation rate of the submodule in the energy storage system; determine the filter parameters in the correlation according to the relevant parameters and the correlation between the filter parameters in the submodule and the relevant parameters, wherein the filter parameters are used to design the LC filter in the submodule, the electrochemical device in the submodule is connected in parallel with the filter capacitor in the LC filter, and in series with the filter inductor in the LC filter, and the filter inductor is located between the electrochemical device and the filter capacitor; the correlation is determined according to the AC / DC network, the AC / DC network is an equivalent circuit of the DC side circuit connected to the half-bridge circuit in the submodule, and when equivalent, the current flowing through the DC side circuit is equivalent to the superposition of DC current, base frequency AC, and double frequency AC.

[0013] In combination with a possible implementation manner of the embodiment of the second aspect, the related parameters also include: the internal resistance of the electrochemical device.

[0014] In combination with a possible implementation manner of the second aspect embodiment, the correlation includes: a first correlation between the filter parameter and a first related parameter, and a second correlation between the filter parameter and a second related parameter, wherein the first correlation is determined according to the DC network, the baseband AC network and the doubled frequency AC network decomposed from the AC / DC network; the second correlation is determined according to the baseband AC network and the doubled frequency AC network; the filter parameters in the correlation are determined according to the related parameters and the correlation between the filter parameters and the related parameters, including: obtaining a first equation according to the first related parameters in the related parameters and the first correlation, wherein the first related parameters include: the operating frequency of the power grid, the current pulsation rate, and the internal resistance of the electrochemical device; obtaining a second equation according to the second related parameters in the related parameters and the second correlation, wherein the second related parameters include: the operating frequency of the power grid, the current amplitude of the power grid, the modulation ratio of the power grid, the internal resistance of the electrochemical device, the voltage pulsation rate, and the voltage; determining the filter parameters in the correlation according to the first equation and the second equation.

[0015] In conjunction with a possible implementation manner of the embodiment of the second aspect, the expression of the first equation is: Wherein, α is the current pulsation rate, ω1 is 1 times the working frequency of the power grid, ω2 is 2 times the working frequency of the power grid, R b is the internal resistance of the electrochemical device, L is the inductance value in the filter parameters, and C is the capacitance value in the filter parameters.

[0016] In the embodiment of the present application, the range of the parameters of the LC filter can be quickly and accurately obtained based on the above expression.

[0017] In conjunction with a possible implementation manner of the embodiment of the second aspect, the expression of the second equation is: Wherein, β is the voltage pulsation rate, ω1 is 1 times the working frequency of the power grid, ω2 is 2 times the working frequency of the power grid, R b is the internal resistance of the electrochemical device, L is the inductance value in the filter parameter, C is the capacitance value in the filter parameter, V bat is the voltage, M is the modulation ratio of the power grid, I m is the current amplitude of the power grid.

[0018] In the embodiment of the present application, the range of the parameters of the LC filter can be quickly and accurately obtained based on the above expression.

[0019] In combination with a possible implementation manner of the embodiment of the second aspect, before determining the filter parameters in the correlation according to the relevant parameters and the correlation between the filter parameters and the relevant parameters in the submodule, the method also includes: obtaining the current component of the electrochemical device branch in the submodule, the current component including the DC component of the electrochemical device branch, the fundamental frequency current component of the electrochemical device branch, and the double frequency current component of the electrochemical device branch; obtaining the voltage component of the capacitor branch in the submodule, the voltage component including the first voltage pulsation generated by the fundamental frequency current in the capacitor branch, and the second voltage pulsation generated by the double frequency current in the capacitor branch; obtaining a first correlation according to the current component of the electrochemical device branch in the submodule; obtaining a second correlation according to the voltage component of the capacitor branch in the submodule and the voltage, wherein the correlation includes the first correlation and the second correlation.

[0020] In an embodiment of the present application, by obtaining the current component of the electrochemical device branch in the sub-module, the first correlation can be accurately obtained, such as the first correlation is the ratio of the sum of the fundamental frequency current component and the double frequency current component to the DC component; by obtaining the voltage component of the capacitor branch in the sub-module, the second correlation can be accurately obtained, such as the second correlation is the ratio of the sum of the first voltage pulsation and the second voltage pulsation to the voltage of the sub-module.

[0021] In combination with a possible implementation manner of the second aspect embodiment, obtaining the current component of the electrochemical device branch in the submodule includes: decomposing the AC / DC network into a DC network, a baseband AC network, and a doubled frequency AC network; based on the DC network, obtaining the DC component of the electrochemical device branch; based on the baseband AC network, obtaining the baseband current component of the electrochemical device branch; based on the doubled frequency AC network, obtaining the doubled frequency current component of the electrochemical device branch.

[0022] In the embodiment of the present application, by decomposing the equivalent circuit of the DC side circuit connected to the half-bridge circuit in the sub-module (i.e., the AC / DC network) into the superposition of the DC network, the baseband AC network, and the doubled frequency AC network, the DC component, the baseband current component, and the doubled frequency current component of the electrochemical device branch can be accurately determined.

[0023] In combination with a possible implementation method of the second aspect, the voltage component of the capacitor branch in the submodule is obtained, including: decomposing the AC / DC network to obtain a baseband AC network and a doubled frequency AC network; based on the baseband AC network, determining a first voltage pulsation generated by the baseband current in the capacitor branch; based on the doubled frequency AC network, determining a second voltage pulsation generated by the doubled frequency current in the capacitor branch.

[0024] In an embodiment of the present application, by decomposing the equivalent circuit of the DC side circuit connected to the half-bridge circuit in the sub-module (i.e., the AC / DC network) into the superposition of a DC network, a baseband AC network, and a double-frequency AC network, the first voltage pulsation generated by the baseband current in the capacitor branch and the second voltage pulsation generated by the double-frequency current in the capacitor branch can be accurately determined.

[0025] In a third aspect, an embodiment of the present application further provides a filter parameter acquisition device, comprising: an acquisition module and a determination module; the acquisition module is used to acquire relevant parameters of the energy storage system, the relevant parameters including: the operating frequency of the power grid to which the energy storage system is connected, the current amplitude of the power grid, the modulation ratio of the power grid, the voltage, current pulsation rate, and voltage pulsation rate of the submodule in the energy storage system; the determination module is used to determine the filter parameters in the correlation according to the relevant parameters and the correlation between the filter parameters and the relevant parameters in the submodule, wherein the filter parameters are used to design an LC filter, the electrochemical device in the submodule is connected in parallel with the filter capacitor in the LC filter, and in series with the filter inductor in the LC filter, and the filter inductor is located between the electrochemical device and the filter capacitor; the correlation is determined according to an AC / DC network, the AC / DC network is an equivalent circuit of the DC side circuit connected to the half-bridge circuit in the submodule, and when equivalent, the current flowing through the DC side circuit is equivalent to the superposition of DC current, baseband AC, and doubled frequency AC.

[0026] In a fourth aspect, an embodiment of the present application further provides an electronic device, comprising: a memory and a processor, the processor being connected to the memory; the memory being used to store programs; the processor being used to call the programs stored in the memory to execute a method provided in the above-mentioned second aspect embodiment and / or any possible implementation method in combination with the second aspect embodiment.

[0027] Other features and advantages of the present application will be described in the following description. The purpose and other advantages of the present application can be realized and obtained through the structures specifically pointed out in the written description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings. The above and other purposes, features and advantages of the present application will be more clearly shown in the drawings.

[0029] Figure 1 A circuit diagram of an energy storage system provided in an embodiment of the present application is shown.

[0030] Figure 2 A circuit diagram of a submodule provided in an embodiment of the present application is shown.

[0031] Figure 3 An equivalent schematic diagram of a DC side circuit provided in an embodiment of the present application is shown.

[0032] Figure 4 A schematic diagram of decomposing an AC / DC network into a DC network, a baseband AC network, and a double-frequency AC network according to an embodiment of the present application is shown.

[0033] Figure 5 A flow chart of a filter parameter acquisition method provided in an embodiment of the present application is shown.

[0034] Figure 6 A module schematic diagram of a filter parameter acquisition device provided in an embodiment of the present application is shown.

[0035] Figure 7 A schematic structural diagram of an electronic device provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying 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 of the embodiments. The following embodiments can be used as examples to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the scope of protection of the present application. It will be appreciated by those skilled in the art that, in the absence of conflict, the features in the following embodiments and embodiments can be combined with each other.

[0037] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it is not necessary to further define and explain it in the subsequent drawings. At the same time, in the description of this application, relational terms such as "first", "second", etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements that are not clearly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements limited by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements.

[0038] Furthermore, the term "and / or" in this application is merely a term used to describe the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B may represent three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0039] In the description of the embodiments of the present application, unless otherwise clearly specified or limited, the technical term “connection” may refer to a direct electrical connection or an indirect electrical connection via an intermediate medium.

[0040] In view of the fact that the relevant technology cannot accurately suppress the pulsating current in the current energy storage system, the current peak of the electrochemical device will exceed the rated current of the electrochemical device, thereby reducing the service life of the electrochemical device. In order to accurately suppress the pulsating current in the current energy storage system, the present application adopts a passive method of a passive filter to suppress the pulsating current in the energy storage system, and suppresses the pulsating current by setting an LC filter in the submodule. Specifically, the electrochemical device in the submodule is connected in parallel with the DC side capacitor through a filter inductor, and the inductor and the capacitor constitute an LC filter, so that the amplitude of the base frequency pulsating current and the double frequency pulsating current in the electrochemical device is greatly attenuated. However, the design of the passive filter is closely related to the efficiency and cost of the submodule, and accurate passive filter parameters need to be obtained.

[0041] In order to obtain accurate passive filter parameters, the embodiment of the present application targets a modular multi-level energy storage system using a passive filter, and performs theoretical modeling and analysis on the pulsating current in the sub-module, and concludes that the pulsating current is composed of DC current, baseband AC and double-frequency AC. Therefore, when the DC side circuit connected to the half-bridge circuit in the sub-module is equivalent, the current flowing through the DC side circuit is equivalent to the superposition of DC current, baseband AC and double-frequency AC, and then the correlation between the filter parameters and related parameters is obtained based on the equivalent AC / DC network, thereby accurately guiding the filter parameter design, and further improving the problem of shortened service life of the electrochemical device due to the influence of pulsating current.

[0042] The electrochemical device is a device or equipment that realizes electrochemical reactions and is used to provide electrical energy, for example, it can be a product such as a battery. The battery can be a lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, etc.

[0043] In one implementation manner, a schematic diagram of an energy storage system provided in an embodiment of the present application is as follows: Figure 1 As shown. It is understandable that Figure 1 The example diagram shown is only a part of the energy storage system, and only shows the part related to the bridge arm. The energy storage system includes multiple bridge arms, each bridge arm includes multiple sub-modules (SM) connected in series, and each bridge arm is connected to one phase of the three-phase AC power grid.

[0044] The filter parameters in each submodule of the energy storage system provided in the embodiment of the present application are determined according to the relevant parameters of the energy storage system and the correlation between the filter parameters and the relevant parameters, so that accurate passive filter parameters can be obtained. Wherein, the correlation is determined according to the AC / DC network, and the AC / DC network is an equivalent circuit of the DC side circuit connected to the half-bridge circuit in the submodule. When equivalent, the current flowing through the DC side circuit is equivalent to the superposition of DC current, baseband AC and double frequency AC, so as to accurately guide the design of filter parameters.

[0045] Among them, the relevant parameters include the operating frequency ω of the power grid to which the energy storage system is connected, the current amplitude I m , the modulation ratio of the power grid M, the voltage of the submodule V bat , the current ripple rate α of the submodule, and the voltage ripple rate β of the submodule.

[0046] The power grid to which the energy storage system is connected can be a three-phase (A, B, C) AC grid, a two-phase AC grid, or a single-phase AC grid. Different AC grids have different operating frequencies, current amplitudes, and modulation ratios.

[0047] Among the above-mentioned related parameters, the operating frequency ω of the power grid and the current amplitude I of the power grid are m The value of the modulation ratio M of the power grid depends on the power grid to which the energy storage system is connected. The voltage V bat Depends on the output voltage of the electrochemical device in the submodule. The current pulsation rate α of the submodule and the voltage pulsation rate β of the submodule can be set according to design requirements. Usually, the current pulsation rate α is not greater than the first threshold, and the voltage pulsation rate β is not greater than the second threshold. Among them, the first threshold and the second threshold are greater than 0, and usually not greater than 1.

[0048] The correlation may include: a first correlation between a filter parameter and a first correlation parameter, and a second correlation between a filter parameter and a second correlation parameter, wherein the first correlation is determined according to a DC network, a baseband AC network, and a double-frequency AC network decomposed from an AC / DC network; and the second correlation is determined according to the baseband AC network and the double-frequency AC network. The filter parameters in each submodule are determined according to the relevant parameters of the energy storage system, the first correlation, and the second correlation.

[0049] Among them, the first equation can be obtained according to the first related parameters and the first correlation in the related parameters, and the second equation can be obtained according to the second related parameters and the second correlation in the related parameters. Then, the filter parameters in the submodule can be obtained according to the first equation and the second equation. In an optional implementation, the first related parameters include: the operating frequency of the power grid, the current pulsation rate of the submodule. The second related parameters include: the operating frequency of the power grid, the current amplitude of the power grid, the modulation ratio of the power grid, the voltage pulsation rate of the submodule, and the voltage of the submodule. In the embodiment of the present application, it is only necessary to substitute the first related parameter into the first correlation to obtain the first equation, and substitute the second related parameter into the second correlation to obtain the second equation. By solving the first equation and the second equation, the parameters of the LC filter can be quickly and accurately obtained.

[0050] The first related parameters include: the operating frequency of the power grid, the current pulsation rate of the submodule, and the expression of the first equation is:

[0051]

[0052] Among them, α is the current ripple rate of the submodule, ω1 is 1 times the operating frequency of the power grid, ω2 is 2 times the operating frequency of the power grid, L is the inductance value in the filter parameters, and C is the capacitance value in the filter parameters.

[0053] The first correlation is similar to the first equation, and the expression obtained by substituting the value of the first correlation parameter into the first correlation is the first equation.

[0054] The second related parameters include: the working frequency of the power grid, the current amplitude of the power grid, the modulation ratio of the power grid, the voltage pulsation rate of the submodule, and the voltage of the submodule. The expression of the second equation is:

[0055]

[0056] Among them, β is the voltage ripple rate of the submodule, ω1 is 1 times the working frequency of the power grid, ω2 is 2 times the working frequency of the power grid, L is the inductance value in the filter parameters, C is the capacitance value in the filter parameters, V bat is the voltage of the submodule, M is the modulation ratio of the grid, I m is the current amplitude of the power grid.

[0057] The second correlation is similar to the second equation, and the expression obtained by substituting the value of the second correlation parameter into the second correlation is the second equation.

[0058] The filter parameters in the present application include: inductance value L and capacitance value C. In the above first equation and second equation, only L and C are unknowns, and the remaining parameters are all known values. By solving the set of equations, the filter parameters can be determined.

[0059] In one embodiment, since the internal resistance of the electrochemical device is relatively large, the internal resistance of the electrochemical device should also be taken into account when designing the filter parameters in the submodule. In this case, the relevant parameters also include the internal resistance of the electrochemical device, such as R b In the present application, by taking the internal resistance of the electrochemical device into consideration, the designed filter parameters are more accurate and can better suppress the pulsating current in the current energy storage system.

[0060] When the relevant parameters also include the internal resistance of the electrochemical device, the first relevant parameters include: the operating frequency of the power grid, the current pulsation rate of the submodule, and the internal resistance of the electrochemical device. The second relevant parameters include: the operating frequency of the power grid, the current amplitude of the power grid, the modulation ratio of the power grid, the voltage pulsation rate of the submodule, the voltage of the submodule, and the internal resistance of the electrochemical device.

[0061] The first related parameter also includes: the internal resistance of the electrochemical device, and the expression of the first equation is:

[0062]

[0063] Among them, α is the current pulsation rate of the submodule, ω1 is 1 times the working frequency of the power grid, ω2 is 2 times the working frequency of the power grid, R b is the internal resistance of the electrochemical device, L is the inductance value in the filter parameters, and C is the capacitance value in the filter parameters.

[0064] The second related parameter also includes: the internal resistance of the electrochemical device, and the expression of the second equation is:

[0065]

[0066] Among them, β is the voltage ripple rate of the submodule, ω1 is 1 times the working frequency of the power grid, ω2 is 2 times the working frequency of the power grid, R b is the internal resistance of the electrochemical device, L is the inductance value in the filter parameters, C is the capacitance value in the filter parameters, V bat is the voltage of the submodule, M is the modulation ratio of the grid, I m is the current amplitude of the power grid.

[0067] In an optional implementation manner, the correlation relationship including the first correlation relationship and the second correlation relationship may be obtained in the following manner:

[0068] The current component of the electrochemical device branch in the submodule is obtained, and a first correlation is obtained according to the current component of the electrochemical device branch in the submodule, wherein the current component includes a DC component of the electrochemical device branch, a fundamental frequency current component of the electrochemical device branch, and a double frequency current component of the electrochemical device branch; the voltage component of the capacitor branch in the submodule is obtained, and a second correlation is obtained according to the voltage component of the capacitor branch in the submodule and the voltage of the submodule, wherein the voltage component includes a first voltage pulsation generated in the capacitor branch by the fundamental frequency current, and a second voltage pulsation generated in the capacitor branch by the double frequency current.

[0069] In order to better understand the above process, Idc represents the DC component of the electrochemical device branch, ibat1 represents the fundamental frequency current component of the electrochemical device branch, ibat2 represents the double frequency current component of the electrochemical device branch, and v C1 Indicates the first voltage ripple, with v C2 Indicates the second voltage pulsation, then

[0070]

[0071] in, Considering the internal resistance R of the electrochemical device b In case of:

[0072]

[0073]

[0074]

[0075]

[0076] Among them, I dc1mis the current amplitude of the fundamental frequency AC network, I dc2m is the current amplitude of the double frequency AC network, Z C1 is the capacitive impedance in the fundamental frequency AC network, Z b1 is the inductance and internal resistance R in the base frequency AC network b The impedance, Z C2 is the capacitive impedance in the double frequency AC network, Z b2 is the inductance and internal resistance R in the double frequency AC network b impedance.

[0077] Without considering the internal resistance R b In the case of Z b1 is the impedance of the inductor in the fundamental frequency AC network, Z b2 is the impedance of the inductor in the double frequency AC network. At this time, directly change the above ibat1, ibat2, v C1 、v C2 The internal resistance R in the expression b Remove it and you can get the value without considering the internal resistance R b In the case of ibat1, ibat2, v C1 、v C2 expression.

[0078] In a possible implementation, the process of obtaining the current component of the electrochemical device branch in the submodule may be: decomposing the AC / DC network into a DC network, a baseband AC network, and a double frequency AC network; obtaining the DC component of the electrochemical device branch based on the DC network; obtaining the baseband current component of the electrochemical device branch based on the baseband AC network; and obtaining the double frequency current component of the electrochemical device branch based on the double frequency AC network. The AC / DC network is an equivalent circuit of the DC side circuit connected to the half-bridge circuit in the submodule.

[0079] For a better understanding, the following Figure 2 The circuit schematic diagram of the submodule shown is used for explanation. In addition to the LC filter, each submodule also includes an electrochemical device and a half-bridge circuit, wherein one side of the half-bridge circuit is connected to the AC network, and the other side of the half-bridge circuit is connected to the LC filter, and the LC filter is connected to the electrochemical device. Specifically, the electrochemical device is connected in series with the filter inductor in the LC filter, and in parallel with the filter capacitor in the LC filter, and the filter inductor is located between the electrochemical device and the filter capacitor. Figure 2 The part where the electrochemical device and the LC filter are located is the DC side circuit connected to the half-bridge circuit in the sub-module.

[0080] The equivalent schematic diagram of the DC side circuit is as follows: Figure 3 As shown, it can be Figure 3 The left part of is equivalent to Figure 3 The right part of the middle part is obtained to obtain the AC / DC network. When equivalent, the current flowing through the DC side circuit is equivalent to the superposition of DC current, base frequency AC and double frequency AC. Ignoring the influence of high frequency components, we can further Figure 3 The AC and DC network on the right is decomposed into Figure 4 The superposition of the DC network, the fundamental frequency AC network and the double frequency AC network is shown.

[0081] When decomposing the equivalent AC / DC network into Figure 4 After the network model shown in the figure is obtained, the DC component of the electrochemical device branch can be obtained based on the DC network, the fundamental frequency current component of the electrochemical device branch can be obtained based on the fundamental frequency AC network, and the double frequency current component of the electrochemical device branch can be obtained based on the double frequency AC network. For example, by solving the DC network, the DC component of the current I can be obtained. b =I dc By solving the fundamental frequency AC network, we can get the fundamental frequency current component ibat1, and by solving the double frequency AC network, we can get the double frequency current component ibat2.

[0082] In some possible implementations, the process of obtaining the voltage component of the capacitor branch in the submodule may be: directly obtaining from a database, in which the voltage component of the capacitor branch in the submodule is pre-stored.

[0083] In some possible implementations, the process of obtaining the voltage component of the capacitor branch in the submodule may be: decomposing the AC / DC network to obtain a baseband AC network and a double frequency AC network, determining the first voltage pulsation generated by the baseband current in the capacitor branch based on the baseband AC network; and determining the second voltage pulsation generated by the double frequency current in the capacitor branch based on the double frequency AC network. The AC / DC network is an equivalent circuit of the DC side circuit connected to the half-bridge circuit in the submodule.

[0084] For ease of understanding, combined Figure 3 , Figure 4 The schematic diagram shown in the figure is used to illustrate that, ignoring the influence of high-frequency components, we can further Figure 3 The AC and DC network on the right is decomposed into Figure 4 The DC network, base frequency AC network and double frequency AC network are superimposed as shown in the figure. Then, based on Figure 4 The fundamental frequency AC network in the circuit determines the first voltage pulsation generated by the fundamental frequency current in the capacitor branch. Figure 4 The double frequency AC network in the circuit is used to determine the second voltage pulsation generated by the double frequency current in the capacitor branch. For example, the phasor method can be used to calculate the first voltage pulsation v generated by the base frequency current in the base frequency AC network. C1, use the phasor method to calculate the second voltage ripple v generated by the double frequency current in the double frequency AC network C2 .

[0085] In the above implementation method, because the pulsating current in the sub-module is theoretically modeled and analyzed to obtain its components including DC component, baseband component and double frequency component, the above AC / DC network is decomposed into the superposition of DC network, baseband AC network and double frequency AC network.

[0086] For a better understanding, the following Figure 1 The energy storage system shown in the figure is used to illustrate that when only the fundamental frequency component is considered, taking phase A as an example, the switching function S of the upper bridge arm ap It can be expressed as follows:

[0087] S ap =M dc -Msinωt, where U dc is the DC component of the upper bridge arm voltage, U mj is the voltage amplitude of the j-phase grid. Taking phase A as an example, phase j = phase A, N is the number of bridge arms, and I m is the current amplitude of the power grid, U c is the average value of the capacitor voltage of each submodule, which is usually equal to the voltage V bat Without considering the circulating current, the currents flowing through the upper bridge arm and lower bridge arm of phase A are and Then we have:

[0088]

[0089] in, is the phase angle difference between voltage and current, when hour, It can be seen that the current flowing through the submodule includes DC component, fundamental frequency component and double frequency component. At the same time, the proportion of AC component is relatively large. If no suppression measures are taken, a large pulsating current will flow in the current, affecting the life of the battery.

[0090] In the present application example, in order to analyze Figure 1 The harmonic components of the electrochemical device current during four-quadrant operation of the energy storage system shown in the figure derive the analytical expression of the DC side ripple current in the submodule based on the switching function.

[0091] The AC side output voltage and current of a submodule of the upper bridge arm of phase A are:

[0092] v apj =V mapj (1+cosωt);

[0093] Among them, V mapj is the output voltage amplitude of the submodule, generally Ignoring the effect of filter inductance, it can be approximately considered to be in phase with the grid voltage. Ignoring the high-frequency component, the DC side ripple current i is derived based on the switching function. DC The analytical expression is:

[0094]

[0095]

[0096] in, Usually V bat =U c Decomposing the DC side ripple current analytical expression, we can get the DC component of the DC side current I dc , fundamental frequency component i dc_1 (t), double frequency component i dc_2 (t) are:

[0097]

[0098]

[0099]

[0100] Based on the analytical expression of the DC side ripple current, we know that:

[0101] The present application also provides a filter parameter acquisition method, by which the parameters of the LC filter in the submodule can be quickly and accurately determined, thereby accurately guiding the design of the LC filter. In one possible implementation, the electrochemical device in the submodule is connected in parallel with the filter capacitor in the LC filter, and is connected in series with the filter inductor in the LC filter. The filter inductor is located between the electrochemical device and the filter capacitor. Figure 5 The process shown illustrates the filter parameter acquisition method provided in the embodiment of the present application.

[0102] S1: Acquire relevant parameters of the energy storage system, including: the operating frequency of the power grid to which the energy storage system is connected, the current amplitude of the power grid, the modulation ratio of the power grid, the voltage, current pulsation rate, and voltage pulsation rate of the submodules in the energy storage system.

[0103] In an optional implementation, the relevant parameters of the energy storage system may be obtained from a local database and / or a third party, or the relevant parameters may be prepared in advance for subsequent use. In some possible implementations, the relevant parameters of the energy storage system may also be obtained in real time, such as the relevant parameters of the energy storage system input by the user may be obtained in real time.

[0104] In some possible implementations, when designing the filter parameters in the submodule, the internal resistance of the electrochemical device should also be taken into account. In this case, the relevant parameters also include the internal resistance of the electrochemical device, such as R b express.

[0105] S2: Determine the filter parameters in the correlation according to the correlation parameters and the correlation between the filter parameters in the submodule and the correlation parameters.

[0106] After the relevant parameters are obtained, the filter parameters can be determined based on the obtained relevant parameters and the correlation between the filter parameters and the relevant parameters in the predetermined submodule, and then the LC filter can be designed according to the determined filter parameters. Among them, the filter parameters are used to design the LC filter. The correlation is determined according to the AC / DC network, and the AC / DC network is an equivalent circuit of the DC side circuit connected to the half-bridge circuit in the submodule. When equivalent, the current flowing through the DC side circuit is equivalent to the superposition of DC current, base frequency AC and double frequency AC.

[0107] The correlation relationship represents the relationship between the filter parameters and the related parameters, and may be an expression including the filter parameters and the related parameters.

[0108] In one implementation, the correlation may include: a first correlation between a filter parameter and a first related parameter, and a second correlation between a filter parameter and a second related parameter, wherein the first correlation is determined according to a DC network, a baseband AC network, and a double frequency AC network decomposed from an AC / DC network; and the second correlation is determined according to a baseband AC network and a double frequency AC network. The first related parameter includes: an operating frequency of the power grid, and a current pulsation rate of a submodule. The second related parameter includes: an operating frequency of the power grid, a current amplitude of the power grid, a modulation ratio of the power grid, a voltage pulsation rate of a submodule, and a voltage of a submodule.

[0109] The first correlation relationship represents the correlation relationship between the first correlation parameter and the filter parameter, which can be an expression including the filter parameter and the first correlation parameter. Similarly, the second correlation relationship represents the correlation relationship between the second correlation parameter and the filter parameter, which can be an expression including the filter parameter and the second correlation parameter.

[0110] When the relevant parameters include a first correlation relationship and a second correlation relationship, the implementation process of S2 can be: obtaining a first equation based on the first relevant parameters and the first correlation relationship in the relevant parameters, obtaining a second equation based on the second relevant parameters and the second correlation relationship in the relevant parameters, and determining the filter parameters in the correlation relationship based on the first equation and the second equation.

[0111] Wherein, when the relevant parameters also include the internal resistance of the electrochemical device, correspondingly, the first relevant parameter and the second relevant parameter both also include the internal resistance of the electrochemical device. At this time, the first relevant parameter includes: the operating frequency of the power grid, the current pulsation rate of the submodule, and the internal resistance of the electrochemical device; the second relevant parameter includes: the operating frequency of the power grid, the current amplitude of the power grid, the modulation ratio of the power grid, the internal resistance of the electrochemical device, the voltage pulsation rate of the submodule, and the voltage of the submodule.

[0112] In an optional implementation manner, when the first related parameter also includes the internal resistance of the electrochemical device, the expression of the first equation is:

[0113]

[0114] When the second related parameter also includes the internal resistance of the electrochemical device, the expression of the second equation is:

[0115]

[0116] In an optional implementation, before S2, the filter parameter acquisition method also includes: acquiring the current component of the electrochemical device branch in the sub-module, wherein the current component includes the DC component of the electrochemical device branch, the fundamental frequency current component of the electrochemical device branch, and the double frequency current component of the electrochemical device branch; obtaining a first correlation based on the current component of the electrochemical device branch in the sub-module; and acquiring the voltage component of the capacitor branch in the sub-module, wherein the voltage component includes a first voltage pulsation generated by the fundamental frequency current in the capacitor branch, and a second voltage pulsation generated by the double frequency current in the capacitor branch; obtaining a second correlation based on the voltage component and voltage of the capacitor branch in the sub-module.

[0117] In one implementation mode, the process of obtaining the current component of the electrochemical device branch in the submodule can be: decomposing the AC / DC network into a DC network, a baseband AC network and a doubled frequency AC network, wherein the AC / DC network is an equivalent circuit of the DC side circuit connected to the half-bridge circuit in the submodule; based on the DC network, obtaining the DC component of the electrochemical device branch; based on the baseband AC network, obtaining the baseband current component of the electrochemical device branch; based on the doubled frequency AC network, obtaining the doubled frequency current component of the electrochemical device branch.

[0118] In one implementation mode, the process of obtaining the voltage component of the capacitor branch in the submodule can be: decomposing the AC / DC network to obtain a baseband AC network and a doubled frequency AC network, wherein the AC / DC network is an equivalent circuit of the DC side circuit connected to the half-bridge circuit in the submodule; based on the baseband AC network, determining the first voltage pulsation generated by the baseband current in the capacitor branch; based on the doubled frequency AC network, determining the second voltage pulsation generated by the doubled frequency current in the capacitor branch.

[0119] The filter parameter acquisition method provided in the embodiment of the present application has the same implementation principle and technical effects as those in the aforementioned energy storage system embodiment. For the sake of brief description, for matters not mentioned in the method embodiment, reference may be made to the corresponding contents in the aforementioned energy storage system embodiment.

[0120] The present application also provides a filter parameter acquisition device 100, such as Figure 6 The filter parameter acquisition device 100 comprises: an acquisition module 110 and a determination module 120 .

[0121] The acquisition module 110 is used to acquire relevant parameters of the energy storage system, including: the operating frequency of the power grid to which the energy storage system is connected, the current amplitude of the power grid, the modulation ratio of the power grid, the voltage, current pulsation rate, and voltage pulsation rate of the submodules in the energy storage system.

[0122] The determination module 120 is used to determine the filter parameters in the correlation according to the correlation parameters and the correlation between the filter parameters in the submodules and the correlation parameters, wherein the filter parameters are used to design an LC filter.

[0123] The correlation includes: a first correlation between the filter parameter and a first correlation parameter, and a second correlation between the filter parameter and a second correlation parameter; a determination module 120 is used to obtain a first equation according to a first correlation parameter among the correlation parameters and the first correlation, wherein the first correlation parameter includes: the operating frequency of the power grid, the current pulsation rate, and the internal resistance of the electrochemical device; a second equation is obtained according to a second correlation parameter among the correlation parameters and the second correlation, wherein the second correlation parameter includes: the operating frequency of the power grid, the current amplitude of the power grid, the modulation ratio of the power grid, the internal resistance of the electrochemical device, the voltage pulsation rate, and the voltage; and the filter parameters in the correlation are determined according to the first equation and the second equation.

[0124] Optionally, the acquisition module 110 is also used to acquire the current component of the electrochemical device branch in the submodule, the current component including the DC component of the electrochemical device branch, the fundamental frequency current component of the electrochemical device branch, and the double frequency current component of the electrochemical device branch; acquire the voltage component of the capacitor branch in the submodule, the voltage component including the first voltage pulsation generated by the fundamental frequency current in the capacitor branch, and the second voltage pulsation generated by the double frequency current in the capacitor branch; obtain a first correlation based on the current component of the electrochemical device branch in the submodule; obtain a second correlation based on the voltage component of the capacitor branch in the submodule and the voltage, wherein the correlation includes the first correlation and the second correlation.

[0125] Optionally, the acquisition module 110 is also used to decompose the AC / DC network into a DC network, a baseband AC network and a doubled frequency AC network, wherein the AC / DC network is an equivalent circuit of the DC side circuit connected to the half-bridge circuit in the submodule; based on the DC network, the DC component of the electrochemical device branch is obtained; based on the baseband AC network, the baseband current component of the electrochemical device branch is obtained; based on the doubled frequency AC network, the doubled frequency current component of the electrochemical device branch is obtained.

[0126] Optionally, the acquisition module 110 is also used to decompose the AC / DC network to obtain a baseband AC network and a doubled frequency AC network, wherein the AC / DC network is an equivalent circuit of the DC side circuit connected to the half-bridge circuit in the submodule; based on the baseband AC network, determine the first voltage pulsation generated by the baseband current in the capacitor branch; based on the doubled frequency AC network, determine the second voltage pulsation generated by the doubled frequency current in the capacitor branch.

[0127] The filter parameter acquisition device 100 provided in the embodiment of the present application has the same implementation principle and technical effects as those of the aforementioned method embodiment. For the sake of brief description, for matters not mentioned in the device embodiment, reference may be made to the corresponding contents in the aforementioned method embodiment.

[0128] like Figure 7 As shown, Figure 7 The electronic device 200 provided in the embodiment of the present application is shown in the structural block diagram. The electronic device 200 comprises: a transceiver 210, a memory 220, a communication bus 230 and a processor 240.

[0129] The transceiver 210, the memory 220, and the processor 240 are electrically connected to each other directly or indirectly to achieve data transmission or interaction. For example, these components can be electrically connected to each other via one or more communication buses 230 or signal lines. The transceiver 210 is used to send and receive data. The memory 220 is used to store computer programs, such as storing Figure 6 The software function module shown in is the filter parameter acquisition device 100. The filter parameter acquisition device 100 includes at least one software function module that can be stored in the memory 220 in the form of software or firmware or solidified in the operating system (OS) of the electronic device 200. The processor 240 is used to execute the executable module stored in the memory 220, such as the software function module or computer program included in the filter parameter acquisition device 100. For example, the processor 240 is used to execute the above-mentioned filter parameter acquisition method.

[0130] Among them, the memory 220 can be, but is not limited to, random access memory (Random Access Memory, RAM), read only memory (Read Only Memory, ROM), programmable read-only memory (Programmable Read-Only Memory, PROM), erasable programmable read-only memory (Erasable Programmable Read-Only Memory, EPROM), electrically erasable read-only memory (Electric Erasable Programmable Read-Only Memory, EEPROM), etc.

[0131] The processor 240 may be an integrated circuit chip with signal processing capabilities. The above-mentioned processor may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), a microprocessor, etc.; it may also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The various methods, steps and logic block diagrams disclosed in the embodiments of the present application may be implemented or executed. Alternatively, the processor 240 may also be any conventional processor, etc.

[0132] The electronic device 200 mentioned above includes, but is not limited to, a mobile phone, a tablet, a computer, a server, etc.

[0133] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0134] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A filter parameter acquisition method, characterized in that: include: Acquire relevant parameters of the energy storage system, the relevant parameters including: the operating frequency of the power grid to which the energy storage system is connected, the current amplitude of the power grid, the modulation ratio of the power grid, the voltage, current pulsation rate, and voltage pulsation rate of the submodules in the energy storage system; According to the relevant parameters and the correlation between the filter parameters and the relevant parameters in the submodule, the filter parameters in the correlation are determined, wherein the filter parameters are used to design the LC filter in the submodule, the electrochemical device in the submodule is connected in parallel with the filter capacitor in the LC filter, and in series with the filter inductor in the LC filter, and the filter inductor is located between the electrochemical device and the filter capacitor; the relevant relationship is determined according to the AC / DC network, and the AC / DC network is an equivalent circuit of the DC side circuit connected to the half-bridge circuit in the submodule, and when equivalent, the current flowing through the DC side circuit is equivalent to the superposition of DC current, base frequency AC and double frequency AC.

2. The method according to claim 1, characterized in that The related parameters also include: the internal resistance of the electrochemical device.

3. The method according to claim 2, characterized in that The correlation relationship includes: a first correlation relationship between the filter parameter and a first correlation parameter, and a second correlation relationship between the filter parameter and a second correlation parameter, wherein the first correlation relationship is determined according to a DC network, a baseband AC network, and a double frequency AC network decomposed from the AC / DC network; and the second correlation relationship is determined according to the baseband AC network and the double frequency AC network; The determining the filter parameters in the correlation according to the correlation parameters and the correlation between the filter parameters and the correlation parameters comprises: According to a first related parameter among the related parameters and the first related relationship, a first equation is obtained, wherein the first related parameter includes: an operating frequency of the power grid, the current pulsation rate, and an internal resistance of the electrochemical device; A second equation is obtained according to a second related parameter in the related parameters and the second related relationship, wherein the second related parameter includes: an operating frequency of the power grid, a current amplitude of the power grid, a modulation ratio of the power grid, an internal resistance of the electrochemical device, the voltage pulsation rate, and the voltage; According to the first equation and the second equation, filter parameters in the correlation relationship are determined.

4. The method according to claim 3, characterized in that The expression of the first equation is: Wherein, α is the current pulsation rate, ω1 is 1 times the working frequency of the power grid, ω2 is 2 times the working frequency of the power grid, R b is the internal resistance of the electrochemical device, L is the inductance value in the filter parameters, and C is the capacitance value in the filter parameters.

5. The method according to claim 3, characterized in that: The expression of the second equation is: Wherein, β is the voltage pulsation rate, ω1 is 1 times the working frequency of the power grid, ω2 is 2 times the working frequency of the power grid, R b is the internal resistance of the electrochemical device, L is the inductance value in the filter parameter, C is the capacitance value in the filter parameter, V bat is the voltage, M is the modulation ratio of the power grid, I m is the current amplitude of the power grid.

6. The method according to any one of claims 1 to 5, characterized in that Before determining the filter parameters in the correlation according to the correlation parameters and the correlation between the filter parameters in the submodule and the correlation parameters, the method further includes: Acquire current components of the electrochemical device branch in the submodule, wherein the current components include a direct current component of the electrochemical device branch, a fundamental frequency current component of the electrochemical device branch, and a double frequency current component of the electrochemical device branch; Obtaining a first correlation according to a current component of a branch of an electrochemical device in the submodule; Acquire a voltage component of the capacitor branch in the submodule, wherein the voltage component includes a first voltage pulsation generated by a base frequency current in the capacitor branch and a second voltage pulsation generated by a double frequency current in the capacitor branch; A second correlation is obtained according to the voltage component of the capacitor branch in the submodule and the voltage, wherein the correlation includes the first correlation and the second correlation.

7. The method according to claim 6, characterized in that Obtaining the current component of the electrochemical device branch in the submodule includes: Decomposing the AC / DC network into a DC network, a baseband AC network and a double frequency AC network; Based on the DC network, obtaining a DC component of the electrochemical device branch; Based on the fundamental frequency AC network, obtaining the fundamental frequency current component of the electrochemical device branch; Based on the double frequency AC network, a double frequency current component of the electrochemical device branch is obtained.

8. The method according to claim 6, characterized in that Obtaining a voltage component of a capacitor branch in the submodule includes: Decomposing the AC / DC network to obtain the baseband AC network and the doubled frequency AC network; Based on the baseband AC network, determining a first voltage pulsation generated by the baseband current in the capacitor branch; Based on the double frequency AC network, a second voltage pulsation generated by the double frequency current in the capacitor branch is determined.

9. An energy storage system, characterized in that: The method comprises: a submodule, wherein the submodule comprises: an LC filter and an electrochemical device, wherein the electrochemical device is connected in parallel with a filter capacitor in the LC filter and in series with a filter inductor in the LC filter, and the filter inductor is located between the electrochemical device and the filter capacitor; Wherein, the parameters of the LC filter are determined according to the method according to any one of claims 1-8.

10. A filter parameter acquisition device, characterized in that: include: An acquisition module is used to acquire relevant parameters of the energy storage system, wherein the relevant parameters include: the operating frequency of the power grid to which the energy storage system is connected, the current amplitude of the power grid, the modulation ratio of the power grid, the voltage, current pulsation rate, and voltage pulsation rate of the submodules in the energy storage system; A determination module is used to determine the filter parameters in the correlation according to the relevant parameters and the correlation between the filter parameters in the submodule and the relevant parameters, wherein the filter parameters are used to design an LC filter, the electrochemical device in the submodule is connected in parallel with the filter capacitor in the LC filter, and is connected in series with the filter inductor in the LC filter, and the filter inductor is located between the electrochemical device and the filter capacitor; the correlation is determined according to an AC / DC network, and the AC / DC network is an equivalent circuit of a DC side circuit connected to a half-bridge circuit in the submodule, and when equivalent, the current flowing through the DC side circuit is equivalent to the superposition of a DC current, a base frequency AC, and a double frequency AC.

11. An electronic device, characterized in that: include: A memory and a processor, wherein the processor is connected to the memory; The memory is used to store programs; The processor is used to call the program stored in the memory to execute the method according to any one of claims 1 to 9.

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