Frequency processing method of energy storage converter, electronic device and storage medium

Abstract

The application provides a frequency processing method of an energy storage converter, an electronic device and a storage medium, and relates to the technical field of energy storage systems. The method comprises the following steps: determining a frequency forbidden zone set corresponding to a grid active filter compensation current according to current spectrum information; determining excitation current sweep information according to the frequency forbidden zone set and a sweep frequency band of the excitation current, wherein the excitation current sweep information comprises a plurality of excitation current sweep frequency bands and a plurality of frequency points corresponding to each excitation current sweep frequency band; performing sweep frequency of a dispatch current according to a sweep frequency band and a channel corresponding to the dispatch current; performing sweep frequency of the excitation current according to the excitation current sweep information and a channel corresponding to the excitation current; and performing sweep frequency of the grid active filter compensation current according to a sweep frequency band and a channel corresponding to the grid active filter compensation current. The dual mechanisms of frequency band orthogonal partition and channel isolation avoid spectrum conflict, and ensure that the three functions can be safely and efficiently executed simultaneously in the same energy storage converter.

Description

Technical Field

[0001] This application relates to the field of energy storage system technology, and more specifically, to a frequency processing method, electronic device and storage medium for an energy storage converter. Background Technology

[0002] A power conversion system (PCS) is a power conversion device between an energy storage system and the power grid. In traditional designs, the PCS only executes charge and discharge scheduling commands. However, with the expansion of the functions of energy storage systems, the PCS can also be reused for electrochemical impedance spectroscopy (EIS) excitation injection and active power filter (APF) of the power grid.

[0003] However, when the same energy storage converter PCS simultaneously performs charge / discharge scheduling, EIS excitation injection, and active power filter (APF) functions, spectral conflicts arise. The energy storage converter PCS cannot effectively distinguish between the actively injected EIS excitation signal and the grid characteristic harmonics that need to be compensated, leading to frequency sweep conflicts among the functions. Therefore, ensuring that the frequency sweep operations corresponding to the three functions of charge / discharge scheduling, EIS excitation injection, and active power filter (APF) are executed simultaneously without interference within the same energy storage converter PCS is a problem that needs to be solved. Summary of the Invention

[0004] The purpose of this application is to address the shortcomings of the prior art by providing a frequency processing method, electronic device, and storage medium for an energy storage converter, in order to solve the problem of how to ensure that the frequency sweep operations corresponding to the three functions of charge and discharge scheduling, EIS excitation injection, and active filter (APF) are executed simultaneously without interference in the same energy storage converter PCS.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows: In a first aspect, embodiments of this application provide a frequency processing method for an energy storage converter, the method comprising: Obtain the sweep frequency band and path of each functional current corresponding to the energy storage converter, wherein the functional current includes dispatch current, excitation current and grid active filter compensation current. Obtain the current spectrum information of the current power grid, and determine the frequency forbidden zone set corresponding to the active filter compensation current of the power grid based on the current spectrum information. The current spectrum information includes the harmonic frequencies and harmonic amplitudes of multiple power grid harmonics. Based on the frequency forbidden zone set and the frequency sweep band of the excitation current, the excitation current frequency sweep information is determined. The excitation current frequency sweep information includes multiple excitation current frequency sweep bands and multiple frequency points corresponding to each excitation current frequency sweep band. Perform frequency sweep of the scheduling current according to the frequency band and path corresponding to the scheduling current, perform frequency sweep of the excitation current according to the frequency sweep information of the excitation current and the path corresponding to the excitation current, and perform frequency sweep of the active filter compensation current according to the frequency band and path corresponding to the active filter compensation current of the power grid.

[0006] As one possible implementation, determining the frequency exclusion set corresponding to the active power grid filter compensation current based on the current spectrum information includes: The frequency exclusion width corresponding to each of the power grid harmonics is determined based on the harmonic amplitude of each of the power grid harmonics. Based on the frequency exclusion width and harmonic frequency of each of the power grid harmonics, the frequency exclusion zone corresponding to each of the power grid harmonics is determined. The set of frequency exclusion zones is determined based on the frequency exclusion zones corresponding to each of the aforementioned power grid harmonics.

[0007] As one possible implementation, determining the set of frequency exclusion zones based on the frequency exclusion zones corresponding to each of the power grid harmonics includes: Traverse the frequency exclusion zones corresponding to each of the power grid harmonics. For the current frequency exclusion zone, if the current frequency exclusion zone overlaps with the next frequency exclusion zone, then merge the current frequency exclusion zone and the next frequency exclusion zone into one frequency exclusion zone. After the traversal is complete, each frequency restricted area is added to the frequency restricted area set.

[0008] As one possible implementation, determining the excitation current sweep frequency information based on the frequency forbidden zone set and the sweep frequency band of the excitation current includes: Remove at least one target frequency from the frequency sweep of the excitation current to obtain at least one usable frequency range, wherein the target frequency is a frequency that is in the set of frequency forbidden zones, and each usable frequency range includes at least one usable frequency; Logarithmically spaced sampling is performed on each of the available frequency intervals to obtain multiple sampling frequencies corresponding to each available frequency interval. Arrange the sampling frequencies corresponding to each of the available frequency intervals to obtain the sampling frequency sequence corresponding to each of the available frequency intervals; Each available frequency range is used as an excitation current sweep frequency band, and each sampling frequency in the sampling frequency sequence corresponding to each available frequency range is used as multiple frequency points corresponding to each excitation current sweep frequency band.

[0009] As one possible implementation, the step of performing logarithmically spaced sampling on each of the available frequency intervals to obtain multiple sampling frequencies corresponding to each available frequency interval includes: Obtain the upper and lower frequency limits of the available frequency range, and perform logarithmic operations on the upper and lower frequency limits respectively to obtain the logarithmic start point and logarithmic end point; Based on the upper and lower frequency limits of the available frequency range and the preset number of sampling points, the total number of sampling points in the available frequency range is determined. Based on the logarithmic start point, the logarithmic end point, and the total number of sampling points within the available frequency range, the available frequency range is sampled at equal intervals to obtain multiple sampling frequencies corresponding to the available frequency range.

[0010] As one possible implementation, performing excitation current frequency sweep according to the excitation current frequency sweep information and the path corresponding to the excitation current includes: Based on the rated output current RMS value of the energy storage converter, the current dispatch current RMS value, and the reserved current capacity, the current power margin is determined. The current power margin represents the remaining current margin that can be used for excitation current frequency sweep. Based on the current power margin, determine whether to perform an excitation current frequency sweep. If so, perform an excitation current frequency sweep according to the excitation current frequency sweep information and the path corresponding to the excitation current.

[0011] As one possible implementation, determining whether to perform an excitation current frequency sweep based on the current power margin includes: Compare the current power margin with the effective value of the excitation current required for frequency sweep of the excitation current; If the current power margin is greater than or equal to the effective value of the excitation current required for the excitation current frequency sweep, then the excitation current frequency sweep is determined to be performed, and the excitation current frequency sweep is performed according to the excitation current frequency sweep information and the path corresponding to the excitation current. If the current power margin is less than the effective value of the excitation current required for the excitation current frequency sweep, then the excitation current frequency sweep is postponed.

[0012] As one possible implementation, the method further includes: Encrypted sampling is performed outside the left and right boundaries of the frequency exclusion zones corresponding to each of the power grid harmonics to obtain boundary reference values ​​of the frequency exclusion zones corresponding to each of the power grid harmonics. The boundary reference values ​​include the frequency, impedance amplitude, and phase angle of the left and right boundaries of the frequency exclusion zones corresponding to the power grid harmonics after sampling. Based on the boundary reference values ​​of the frequency forbidden zones corresponding to each of the power grid harmonics, interpolation is performed on each frequency point within the frequency forbidden zones corresponding to each of the power grid harmonics to determine the impedance amplitude and phase angle corresponding to each frequency point within the frequency forbidden zones corresponding to each of the power grid harmonics. Based on the impedance amplitude and phase angle of each frequency point within the frequency restricted area corresponding to each of the aforementioned power grid harmonics, a Nyquist plot is generated for frequency band analysis.

[0013] Secondly, embodiments of this application provide an electronic device, including: a processor, a storage medium, and a bus. The storage medium stores machine-readable instructions executable by the processor. When the electronic device is running, the processor communicates with the storage medium via the bus. The processor executes the machine-readable instructions to perform the steps of the frequency processing method for the energy storage converter as described in any of the first aspects above.

[0014] Thirdly, embodiments of this application provide a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the frequency processing method for the energy storage converter as described in any of the first aspects above.

[0015] According to the frequency processing method, electronic device, and storage medium of the energy storage converter according to the embodiments of this application, in terms of frequency band allocation, the slow-changing characteristics of the charging and discharging scheduling current are used to limit the frequency sweep band to an extremely low frequency band, the frequency sweep band of the APF compensation current is limited to a specific harmonic frequency band, and the frequency sweep band of the EIS excitation current is limited to a frequency band that avoids the frequency sweep band of the APF compensation current. This achieves orthogonal partitioning of the three functions in the frequency domain, avoiding frequency overlap. In terms of signal paths, a narrowband bandpass filter bank is configured for the EIS excitation current, and a narrowband notch filter bank is configured for the APF compensation current. The frequency responses of these two filter banks are strictly non-overlapping in the frequency domain. Thus, the embodiments of this application, through the dual mechanisms of orthogonal frequency band partitioning and path isolation, ensure that the current signals of different functions are isolated from each other on the transmission path, preventing crosstalk and avoiding spectral conflicts. This ensures that the three functions can be safely and efficiently executed simultaneously in the same energy storage converter PCS. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1A schematic flowchart of a frequency processing method for an energy storage converter provided in an embodiment of this application is shown. Figure 2 A flowchart illustrating a method for determining a frequency restricted area set according to an embodiment of this application is shown; Figure 3 A flowchart illustrating a method for determining excitation current sweep frequency information according to an embodiment of this application is shown. Figure 4 A schematic flowchart of a logarithmic interval sampling processing method provided in an embodiment of this application is shown; Figure 5 A flowchart illustrating a frequency sweeping processing method provided in an embodiment of this application is shown; Figure 6 A flowchart illustrating a forbidden zone impedance interpolation method provided in an embodiment of this application is shown. Figure 7 A schematic diagram of the structure of an electronic device provided in an embodiment of this application is shown. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the accompanying drawings in this application are for illustrative and descriptive purposes only and are not intended to limit the scope of protection of this application. Furthermore, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of this application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or implemented simultaneously. In addition, those skilled in the art, guided by the content of this application, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0019] Furthermore, the described embodiments are merely some, not all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0020] It should be noted that the term "comprising" will be used in the embodiments of this application to indicate the presence of the features declared thereafter, but does not exclude the addition of other features.

[0021] Figure 1This diagram illustrates a frequency processing method for an energy storage converter according to an embodiment of this application. The main execution component of this method is a PCS controller. (Refer to...) Figure 1 As shown, the method specifically includes the following steps: S101. Obtain the sweep frequency band and path of each functional current corresponding to the energy storage converter.

[0022] The functional current includes dispatch current, excitation current, and grid active filter compensation current.

[0023] Optionally, when the three functions of charge and discharge scheduling, EIS excitation injection, and active filter (APF) are executed simultaneously in the same energy storage converter PCS, the current reference value of the energy storage converter PCS in the current loop control cycle is the superposition of the three functional currents: scheduling current, excitation current, and grid active filter compensation current, as shown in the following expression (1): (1) in, This represents the current reference value of the energy storage converter PCS during the current loop control cycle. Indicates the dispatch current. Indicates the excitation current. This indicates the active filter compensation current of the power grid.

[0024] For example, scheduling current This is the DC component, originating from the charging and discharging power commands issued by the Energy Management System (EMS). Its frequency characteristic is DC~10Hz, and it is used to execute grid charging and discharging scheduling. Excitation current. This is the AC component, derived from the EIS measurement plan issued by the Battery Management System (BMS), with a frequency characteristic of 0.01Hz~10kHz, used to inject AC excitation into the battery for impedance measurement. The mains active filter compensates for the current. It is the AC component, which comes from the compensation current generated by the PCS controller in real time by detecting grid harmonics. Its frequency characteristic is concentrated in the characteristic harmonic frequency of the grid, that is, an integer multiple of 50Hz, such as 150Hz, 250Hz, 350Hz, 550Hz, etc., which is used to compensate for grid harmonics and provide power quality management services.

[0025] For example, in the embodiments of this application, regarding the above-mentioned scheduling current Excitation current Active power grid filter compensation current The corresponding frequency bands are orthogonally partitioned and allocated. Specifically, since the charging and discharging power scheduling is a slowly changing signal and does not overlap with the EIS and APF frequency bands, the scheduling current... The sweep frequency band is set to DC~10Hz, which is also the scheduling frequency band. The EIS excitation frequency is selected as a clean frequency point that is not an integer multiple of the fundamental frequency, i.e., the excitation current. The frequency sweep band is selected within the range of 0.01Hz to 10kHz, using non-integer multiples of frequencies such as 120Hz, 220Hz, 80Hz, and 15Hz. The bandwidth is determined by the accuracy requirements of the EIS measurement. The APF only provides compensation current at specific harmonic frequencies, therefore the active power grid filter compensation current... The corresponding frequency sweep is concentrated at the characteristic harmonic frequencies of the power grid, such as integer multiples of the fundamental frequency (50Hz / 60Hz), and the bandwidth is determined by the severity of the power grid harmonics.

[0026] Furthermore, in this embodiment, not only are different frequency bands set, but frequency band isolation is also achieved by setting different paths. Specifically, since the charge and discharge power scheduling itself is a slowly changing signal and does not overlap with the EIS and APF frequency bands, the scheduling current... The path is not specially treated; the main focus is on the excitation current. and grid active filter compensation current The path configuration. For the excitation current. In terms of excitation current The path is a narrowband bandpass filter bank, with gain only at selected EIS frequencies. Each EIS frequency corresponds to one narrowband bandpass filter, and the filter bandwidth is determined by the EIS measurement accuracy requirements, for example, ±1~2Hz. This is for active power grid filtering to compensate for current. In terms of active power grid filter compensation current The path is a narrowband notch filter group, which has gain only at the characteristic harmonic frequency of the power grid. Each harmonic frequency corresponds to a narrowband filter with a bandwidth of ±2~5Hz. The filter group covers the 3rd, 5th, 7th, 11th and 13th harmonics.

[0027] It is worth noting that the frequency responses of the APF notch filter group and the EIS bandpass filter group do not overlap in the frequency domain. The response at any APF frequency point is attenuated by more than 40dB at the EIS frequency point, and vice versa.

[0028] S102. Obtain the current spectrum information of the current power grid, and determine the frequency forbidden zone set corresponding to the active filter compensation current of the power grid based on the current spectrum information.

[0029] The current spectrum information includes the harmonic frequencies and harmonic amplitudes of multiple power grid harmonics.

[0030] Optionally, before the frequency sweep begins, the PCS controller first performs grid current spectrum analysis to identify the harmonic frequencies of multiple grid harmonics present in the current grid. and harmonic amplitude Based on this, for each power grid harmonic, the harmonic amplitude of the power grid harmonics is... Calculate the corresponding frequency exclusion width, and then combine the frequency exclusion width with the harmonic frequencies of the power grid harmonics. Identify the frequency exclusion zones corresponding to power grid harmonics. This allows us to obtain the frequency exclusion zones for each power grid harmonic, and thus determine the set of frequency exclusion zones, which includes multiple frequency exclusion zones.

[0031] It should be noted that since the frequency exclusion zones corresponding to the harmonics of different power grids may overlap, in this embodiment of the application, the overlapping frequency exclusion zones can be further merged to obtain a more accurate set of frequency exclusion zones.

[0032] S103. Determine the excitation current sweep frequency information based on the frequency forbidden zone set and the sweep frequency band of the excitation current.

[0033] The excitation current sweep frequency information includes multiple excitation current sweep frequency bands and multiple frequency points corresponding to each excitation current sweep frequency band.

[0034] Optionally, the PCS controller removes the target frequencies within the frequency forbidden zone set from the excitation current sweep frequency band, thereby dividing the excitation current sweep frequency band into multiple discontinuous usable frequency intervals. For each usable frequency interval, a logarithmic interval sampling method is used to calculate multiple sampling frequencies within the usable frequency interval, and each usable frequency interval is used as the final excitation current sweep frequency band, and the multiple sampling frequencies within each usable frequency interval are used as the sweep frequency points of the corresponding excitation current sweep frequency band.

[0035] S104. Perform frequency sweep of dispatch current according to the frequency band and path corresponding to dispatch current, perform frequency sweep of excitation current according to excitation current frequency sweep information and path corresponding to excitation current, and perform frequency sweep of active filter compensation current according to the frequency band and path corresponding to grid active filter compensation current.

[0036] Optionally, during the current loop control cycle, the PCS controller superimposes the reference values ​​of the three functional currents—dispatch current, excitation current, and grid active filter compensation current—to form a total current reference value. Each of these reference values ​​is then used to perform frequency sweeping operations through its respective independent path and frequency band. Specifically, the dispatch current operates through a default path in the low-frequency band of 0–10 Hz; the excitation current is swept through a narrowband bandpass filter bank at usable frequencies excluding frequency restrictions; and the grid active filter compensation current is concentrated at specific grid characteristic harmonic frequencies through a narrowband notch filter bank. These three functional currents operate independently in their respective frequency bands and paths, and are ultimately superimposed and output to the energy storage converter.

[0037] Based on this, the frequency processing method of the energy storage converter according to the embodiments of this application, in terms of frequency band allocation, utilizes the slow-changing characteristics of the charging and discharging scheduling current to limit the frequency sweep band to the extremely low frequency band of 0~10Hz, limits the frequency sweep band of the APF compensation current to a specific harmonic frequency band that is an integer multiple of 50Hz, and limits the frequency sweep band of the EIS excitation current to a frequency band that avoids the frequency sweep band of the APF compensation current. This achieves orthogonal partitioning of the three functions in the frequency domain, avoiding frequency overlap. In terms of signal paths, a narrowband bandpass filter bank is configured for the EIS excitation current, and a narrowband notch filter bank is configured for the APF compensation current. Furthermore, the frequency responses of these two filter banks strictly do not overlap in the frequency domain. Thus, the embodiments of this application, through the dual mechanisms of orthogonal frequency band partitioning and path isolation, ensure that the current signals of different functions are isolated from each other on the transmission path and do not crosstalk, thereby guaranteeing that the three functions can be safely and efficiently executed simultaneously in the same energy storage converter PCS.

[0038] Figure 2 A flowchart illustrating a method for determining a frequency restricted area set according to an embodiment of this application is shown. (Refer to...) Figure 2 As shown, step S102 above determines the frequency exclusion set corresponding to the active filter compensation current of the power grid based on the current spectrum information, specifically including the following steps: S201. Determine the frequency exclusion width corresponding to each power grid harmonic based on the harmonic amplitude of each power grid harmonic.

[0039] Optionally, for each power grid harmonic, the larger the harmonic amplitude, the stronger the interference of power grid harmonics on EIS measurements, and the wider the frequency exclusion zone corresponding to the power grid harmonics. The wider.

[0040] In one implementation, the frequency restricted area width The settings can be adaptively configured based on harmonic amplitude. For example, a harmonic amplitude threshold can be set to measure whether the harmonic amplitude is large or small. If the harmonic amplitude is large, the frequency exclusion zone width is set wider, such as ±10Hz; if the harmonic amplitude is small, the frequency exclusion zone width is set narrower, such as ±2Hz. Specifically, for example, if the harmonic amplitude of the power grid harmonic is greater than the harmonic amplitude threshold, it is determined to be a large harmonic amplitude, and the corresponding frequency exclusion zone width is set to ±10Hz. Conversely, if the harmonic amplitude of the power grid harmonic is less than or equal to the harmonic amplitude threshold, it is determined to be a small harmonic amplitude, and the corresponding frequency exclusion zone width is set to ±2Hz.

[0041] In another implementation, the frequency exclusion width corresponding to the power grid harmonics can be determined according to the following expression (2). : (2) in, This indicates the width of the frequency exclusion zone corresponding to power grid harmonics. This represents the restricted area width scaling factor, used to linearly map harmonic amplitudes to the frequency restricted area width. This indicates the harmonic amplitude of the power grid harmonics.

[0042] For example, in the embodiments of this application, the restricted area width ratio factor The amplitude dimension can be converted to the frequency dimension, with a value of, for example, 0.5~2.0 Hz / A. This value is only an example, and the specific value can be determined according to the PCS current loop bandwidth and the EIS measurement signal-to-noise ratio requirements.

[0043] It is worth noting that, based on the above expression (2), the frequency forbidden zone width corresponding to power grid harmonics is... The method of determination is in and The larger of these two values ​​will be used as the final frequency restricted area width. This ensures that even if the harmonic amplitude is extremely small or zero, the frequency forbidden zone width remains constant. It will not be narrower than ±2Hz, which is also the minimum frequency interval required for EIS single-frequency point measurement.

[0044] S202. Determine the frequency exclusion zones corresponding to each power grid harmonic based on the width of the frequency exclusion zones corresponding to each power grid harmonic and the harmonic frequencies of each power grid harmonic.

[0045] Optionally, for each power grid harmonic, based on the harmonic amplitude of the power grid harmonics... Determine the frequency exclusion width corresponding to power grid harmonics Based on this, the harmonic frequencies of the power grid can be further considered. Identify the frequency exclusion zones corresponding to power grid harmonics; specifically, these frequency exclusion zones are... .

[0046] S203. Determine the set of frequency restricted areas based on the frequency restricted areas corresponding to the harmonics of each power grid.

[0047] Optionally, the frequency exclusion zones corresponding to each power grid harmonic are traversed. For the current frequency exclusion zone encountered, if it overlaps with the next frequency exclusion zone, the current frequency exclusion zone and the next frequency exclusion zone are merged into one frequency exclusion zone. After the traversal is completed, each frequency exclusion zone is added to the frequency exclusion zone set.

[0048] For example, this application provides a method for determining whether the frequency exclusion zones of two adjacent power grid harmonics overlap. Specifically, the harmonic frequency of the power grid harmonic corresponding to the current frequency exclusion zone is denoted as... The current frequency exclusion zone corresponds to a power grid harmonic frequency exclusion zone width of [missing information]. The harmonic frequency of the power grid harmonics corresponding to the next frequency exclusion zone adjacent to the current frequency exclusion zone is: ,like If this is determined, then the current frequency restricted area overlaps with the next frequency restricted area. Therefore, the current frequency restricted area and the next frequency restricted area can be merged into a continuous frequency restricted area to ensure that any frequency point belongs to at most one frequency restricted area.

[0049] For example, when determining the set of frequency exclusion zones, the PCS controller traverses the frequency exclusion zones corresponding to each grid harmonic in ascending order of harmonic frequency. For each frequency exclusion zone encountered, it determines whether the current frequency exclusion zone overlaps with the next frequency exclusion zone in terms of frequency range. If there is an overlap, the current frequency exclusion zone and the next frequency exclusion zone are merged into a continuous frequency exclusion zone to avoid the frequency exclusion zones of adjacent harmonics being separated from each other. This process continues until the frequency exclusion zones corresponding to all grid harmonics have been traversed. Finally, all the merged independent frequency exclusion zones are summarized to form a complete set of frequency exclusion zones.

[0050] For example, if the current frequency restricted area is [48Hz, 52Hz] and the next frequency restricted area is [51Hz, 55Hz], since the current frequency restricted area and the next frequency restricted area overlap in the range of 51Hz to 52Hz, the two frequency restricted areas [48Hz, 52Hz] and the next frequency restricted area [51Hz, 55Hz] are merged into a single frequency restricted area [48Hz, 55Hz]. This ensures that the frequency overlap area is uniformly regarded as an unusable frequency band, effectively avoiding frequency interference.

[0051] Based on this, the embodiments of this application dynamically determine the width of the frequency exclusion zone according to the harmonic amplitude of each power grid harmonic, and merge the frequency exclusion zones that overlap, thereby avoiding harmonic interference areas with large amplitude or dense frequency in the power grid, and effectively eliminating the influence of power grid harmonics on the accuracy of impedance measurement.

[0052] Figure 3 A flowchart illustrating a method for determining excitation current sweep frequency information according to an embodiment of this application is shown. (Refer to...) Figure 3 As shown, step S103 above determines the excitation current sweep frequency information based on the frequency forbidden zone set and the sweep frequency band of the excitation current, specifically including the following steps: S301. Remove at least one target frequency from the frequency sweep of the excitation current to obtain at least one usable frequency range.

[0053] Optionally, the target frequency is a frequency located within a set of frequency restricted areas, and each available frequency range includes at least one available frequency.

[0054] It is worth noting that removing the target frequency from the frequency sweep of the excitation current means excluding the target frequency from the frequency sweep of the excitation current and not arranging the EIS excitation frequency point. It does not mean deleting the target frequency from the physical spectrum, but rather not injecting the EIS excitation current into the frequency forbidden zone set to avoid spectral aliasing with the APF compensation current.

[0055] For example, by removing all target frequencies from the frequency range of the excitation current sweep, which are all within the frequency forbidden zone, multiple discontinuous usable frequency ranges can be obtained, such as... , wait.

[0056] S302. Perform logarithmic interval sampling on each available frequency range to obtain multiple sampling frequencies corresponding to each available frequency range.

[0057] Figure 4 A schematic flowchart of a logarithmic interval sampling processing method provided in an embodiment of this application is shown. (Refer to...) Figure 4 As shown, step S302 specifically includes the following steps: S401. Obtain the upper and lower limits of the available frequency range, and perform logarithmic operations on the upper and lower limits respectively to obtain the starting and ending points of the logarithm.

[0058] Optionally, for an available frequency range In terms of frequency, its upper limit is The lower limit of frequency is For the upper limit of frequency respectively and frequency lower limit Performing logarithmic operations, we can obtain the starting point of the logarithm as... The logarithmic termination point is .

[0059] S402. Based on the upper and lower frequency limits of the available frequency range and the preset number of sampling points, determine the total number of sampling points within the available frequency range.

[0060] Optionally, the total number of sampling points within the available frequency range can be calculated based on the following expression (3): (3) in, Indicates the available frequency range The total number of sampling points within, Indicates the preset number of sampling points in the frequency band. Indicates the upper limit of frequency. Indicates the lower limit of frequency.

[0061] For example, in the embodiments of this application, the preset frequency band sampling point number For example, the number of sampling points per ten octaves, with values ​​ranging from 10 to 20 points.

[0062] S403. Based on the logarithmic start point, logarithmic end point, and the total number of sampling points within the available frequency range, perform equal-interval sampling on the available frequency range to obtain multiple sampling frequencies corresponding to the available frequency range.

[0063] Optionally, for the available frequency range In terms of obtaining the logarithmic starting point Logarithmic termination point and the total number of sampling points Based on this, multiple sampling frequencies, i.e. multiple sampling points, can be obtained by sampling the available frequency range at equal intervals based on the following expression (4): (4) in, Indicates the first Each sampling frequency, , Indicates the starting point of the logarithm. Indicates the endpoint of the logarithm. Indicates the available frequency range The total number of sampling points within the area.

[0064] S303. Arrange the sampling frequencies corresponding to each available frequency range to obtain the sampling frequency sequence corresponding to each available frequency range.

[0065] Optionally, based on obtaining multiple sampling frequencies corresponding to each available frequency range, the multiple sampling frequencies corresponding to each available frequency range can be arranged in ascending order to obtain a sampling frequency sequence corresponding to each available frequency range.

[0066] For example, for the available frequency range The 14 sampling frequencies, arranged in ascending order, are: 0.01Hz, 0.02Hz, 0.05Hz, 0.1Hz, 0.2Hz, 0.5Hz, 1Hz, 2Hz, 5Hz, 10Hz, 20Hz, 50Hz, 100Hz, and 148Hz. For the usable frequency range... The six sampling frequencies, arranged in ascending order, are: 152Hz, 160Hz, 180Hz, 200Hz, 220Hz, and 248Hz. For the usable frequency range... The six sampling frequencies arranged in ascending order are: 252Hz, 270Hz, 290Hz, 310Hz, 330Hz, and 348Hz.

[0067] S304. Each available frequency range is taken as an excitation current sweep frequency band, and each sampling frequency in the sampling frequency sequence corresponding to each available frequency range is taken as multiple frequency points corresponding to each excitation current sweep frequency band.

[0068] Optionally, each available frequency range can be directly used as an independent excitation current sweep frequency band, and each sampled frequency in the sampled frequency sequence obtained after ascending order within each available frequency range can be used as multiple discrete frequency points corresponding to the actual frequency sweep operation within the corresponding excitation current sweep frequency band.

[0069] Based on this, the embodiments of this application obtain multiple discontinuous usable frequency ranges by removing interference frequencies from the frequency forbidden zone set in the frequency sweep band of the excitation current, and use logarithmic interval sampling to determine the frequency points in each usable frequency range, effectively avoiding spectral aliasing between the EIS excitation current and the APF compensation current.

[0070] Figure 5 A schematic flowchart of a frequency sweeping processing method provided in an embodiment of this application is shown. (Refer to...) Figure 5 As shown, the above steps are performed according to the excitation current frequency sweep information and the path corresponding to the excitation current, specifically including the following steps: S501. Determine the current power margin based on the rated output current RMS value of the energy storage converter, the current dispatch current RMS value, and the reserved current capacity.

[0071] The current power margin represents the remaining current margin that can be used for frequency sweeping of the excitation current.

[0072] Optionally, before the EIS excitation is started, the PCS controller first checks the current power margin. Specifically, the current power margin can be calculated based on the following expression (5): (5) in, Indicates the current power margin. This indicates the effective value of the rated output current of the energy storage converter. Indicates the effective value of the current dispatch current. The absolute value, Indicates reserved current capacity The absolute value of.

[0073] Among them, the rated output current RMS value of the energy storage converter The effective value of the current dispatch current is determined by the hardware specifications of the energy storage converter PCS and consists of fixed parameters. Includes DC component and low-frequency fluctuation component, calculated from EMS power command, with reserved current capacity. In other words, the reserved current capacity of the APF function can be calculated by multiplying the sum of the effective values ​​of all harmonic currents in the current power grid by a margin factor. (Usually a value between 1.1 and 1.3) is determined and dynamically updated.

[0074] For example, embodiments of this application provide a reserved current capacity. The specific calculation method involves the PCS controller analyzing the grid current in real time and extracting the effective values ​​of each harmonic (3rd / 5th / 7th / 11th / 13th). And take the effective value of each harmonic. The sum multiplied by the margin factor The reserved current capacity can then be obtained. The reserved current capacity It is not a fixed value, but is updated in real time according to the power grid harmonic conditions.

[0075] S502. Based on the current power margin, determine whether to perform excitation current frequency sweep. If so, perform excitation current frequency sweep according to the excitation current frequency sweep information and the path corresponding to the excitation current.

[0076] Optionally, the current power margin is compared with the effective value of the excitation current required for excitation current frequency sweep. If the current power margin is greater than or equal to the effective value of the excitation current required for excitation current frequency sweep, then the excitation current frequency sweep is determined to be performed, and the excitation current frequency sweep is performed according to the excitation current frequency sweep information and the path corresponding to the excitation current. If the current power margin is less than the effective value of the excitation current required for excitation current frequency sweep, then the excitation current frequency sweep is postponed.

[0077] For example, the effective value of the excitation current required for frequency sweep of the excitation current. It can be determined based on the excitation amplitude requirement of the current frequency sweep point. In this embodiment, if the current power margin... The effective value of the excitation current required for frequency sweep is greater than or equal to the excitation current. , that is If so, then the excitation current frequency sweep is performed, and the excitation current frequency sweep is executed according to the excitation current frequency sweep information and the path corresponding to the excitation current. Conversely, if the current power margin is... The effective value of the excitation current required for frequency sweep is less than the excitation current. , that is If the battery is not in a protected state, the excitation current frequency sweep will be delayed, or the EIS excitation amplitude will be reduced. The EIS excitation amplitude is dynamically limited by the BMS based on the current state of the battery. The BMS monitors the battery terminal voltage, current, and temperature in real time. When the battery approaches the protection threshold, the BMS notifies the PCS controller to reduce the EIS excitation amplitude. When the battery enters the protection grace mode, the BMS notifies the PCS controller to ensure that the EIS excitation amplitude does not exceed the grace limit. In addition, if a thermal runaway warning is detected, the BMS can forcibly terminate the EIS measurement.

[0078] Furthermore, if the scheduling power changes abruptly, the EIS measurement is immediately interrupted, and the interruption point information is recorded, including but not limited to the current frequency, completed frequency points, and remaining frequency points. When the scheduling stabilizes, that is, after the scheduling power change rate is lower than the preset threshold for a period of time, the EIS frequency sweep is resumed from the interruption point, without having to start the frequency sweep from the beginning.

[0079] Based on this, the embodiments of this application calculate the remaining current margin that can be used for excitation current frequency sweep to ensure that the energy storage converter has sufficient current capacity when performing EIS frequency sweep, thereby effectively avoiding overload of the energy storage converter or affecting the normal power dispatch of the energy storage converter due to frequency sweep current injection.

[0080] Figure 6 A schematic flowchart of a forbidden area impedance interpolation method provided in an embodiment of this application is shown. (Refer to...) Figure 6 As shown, the method specifically includes the following steps: S601. Perform encrypted sampling outside the left and right boundaries of the frequency exclusion zones corresponding to each power grid harmonic to obtain the boundary reference values ​​of the frequency exclusion zones corresponding to each power grid harmonic.

[0081] Among them, the boundary reference values ​​include the frequency, impedance amplitude, and phase angle of the left and right boundaries of the frequency exclusion zone corresponding to the power grid harmonics after sampling.

[0082] Optionally, in this embodiment of the application, encrypted sampling is performed outside the left and right boundaries of the frequency restricted area corresponding to each power grid harmonic, so as to add 2 to 3 additional sampling points outside the left and right boundaries of the frequency restricted area. The specific encrypted sampling strategy is to take 2 to 3 sampling points outside the left and right boundaries, and the spacing between these 2 to 3 sampling points increases linearly, that is, the closer to the boundary, the denser they are.

[0083] For example, let the boundary frequency be denoted as Then the first sampling point can be taken as The second sampling point can be taken as The third sampling point can be taken as .in, This indicates the encryption step size, which can typically be 1 to 2 Hz.

[0084] Furthermore, after performing encrypted sampling outside the left and right boundaries of the frequency exclusion zones corresponding to each power grid harmonic, the left and right boundaries of the frequency exclusion zones corresponding to each power grid harmonic are updated, that is, the frequency exclusion zones corresponding to the sampled power grid harmonics are obtained, and then the boundary reference values ​​can be obtained, including the frequencies of the left and right boundaries of the frequency exclusion zones corresponding to the sampled power grid harmonics. and ), impedance amplitude ( and ) and phase angle ( and ),in, Indicates the left boundary, Indicates the right boundary.

[0085] S602. Based on the boundary reference values ​​of the frequency exclusion zones corresponding to each power grid harmonic, interpolate each frequency point within the frequency exclusion zones corresponding to each power grid harmonic to determine the impedance amplitude and phase angle corresponding to each frequency point within the frequency exclusion zones corresponding to each power grid harmonic.

[0086] Optionally, for each frequency exclusion zone corresponding to a power grid harmonic, for any frequency point within the frequency exclusion zone, the frequency of that frequency point is denoted as... In the logarithmic frequency domain, the impedance amplitude is respectively... and phase angle Linear interpolation is performed, specifically based on the following expressions (6) and (7), to calculate the impedance amplitude and phase angle corresponding to the frequency point:

[0087] in, This indicates the impedance amplitude corresponding to the frequency point. This indicates the impedance amplitude corresponding to the left boundary of the frequency forbidden zone. The frequency of the point of frequency, This indicates the frequency corresponding to the left boundary of the frequency forbidden zone. This indicates the impedance amplitude corresponding to the right boundary of the frequency forbidden zone. This indicates the frequency corresponding to the right boundary of the frequency forbidden zone. This indicates the phase angle corresponding to the frequency point. This represents the phase angle corresponding to the left boundary of the frequency restricted area. This indicates the phase angle corresponding to the right boundary of the frequency restricted area.

[0088] S603. Based on the impedance amplitude and phase angle of each frequency point within the frequency restriction zone corresponding to each power grid harmonic, generate a Nyquist plot for frequency band analysis.

[0089] Optionally, after determining the impedance amplitude and phase angle of each frequency point within the frequency restriction zone corresponding to each power grid harmonic, the PCS controller uses the impedance amplitude and phase angle obtained through interpolation as the basis to construct and generate a Nyquist plot, thereby graphically presenting the impedance frequency characteristics including the restricted frequency band in a complete manner, so as to provide more intuitive data support for subsequent frequency band stability analysis.

[0090] Based on this, the embodiments of this application effectively fill the impedance data gaps in the frequency restricted area by performing encrypted sampling outside the boundary of the frequency restricted area and linear interpolation in the logarithmic frequency domain. This solves the problem that the Nyquist plot is discontinuous due to missing data and cannot accurately reflect the impedance characteristics of the entire frequency band, thereby significantly improving the accuracy of frequency band analysis.

[0091] This application also provides an electronic device 700, which is, for example, a PCS controller. Figure 7 The diagram shown is a structural schematic of an electronic device 700 provided in an embodiment of this application, including: a processor 701 and a memory 702, and optionally, a bus 703. The memory 702 stores machine-readable instructions executable by the processor 701. When the electronic device 700 is running, the processor 701 and the memory 702 communicate via the bus 703. When the machine-readable instructions are executed by the processor 701, the steps of the frequency processing method for the energy storage converter as described in any of the preceding claims are executed.

[0092] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, performs the steps of the frequency processing method for the energy storage converter as described in any of the preceding claims.

[0093] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and devices described above can be referred to the corresponding processes in the method embodiments, and will not be repeated here. In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection can be through some communication interfaces; the indirect coupling or communication connection of devices or modules can be electrical, mechanical, or other forms.

[0094] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. If the functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.

[0095] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A frequency processing method for an energy storage converter, characterized in that, include: Obtain the sweep frequency band and path of each functional current corresponding to the energy storage converter, wherein the functional current includes dispatch current, excitation current and grid active filter compensation current. Obtain the current spectrum information of the current power grid, and determine the frequency forbidden zone set corresponding to the active filter compensation current of the power grid based on the current spectrum information. The current spectrum information includes the harmonic frequencies and harmonic amplitudes of multiple power grid harmonics. Based on the frequency forbidden zone set and the frequency sweep band of the excitation current, the excitation current frequency sweep information is determined. The excitation current frequency sweep information includes multiple excitation current frequency sweep bands and multiple frequency points corresponding to each excitation current frequency sweep band. Perform frequency sweep of the scheduling current according to the frequency band and path corresponding to the scheduling current, perform frequency sweep of the excitation current according to the frequency sweep information of the excitation current and the path corresponding to the excitation current, and perform frequency sweep of the active filter compensation current according to the frequency band and path corresponding to the active filter compensation current of the power grid.

2. The method according to claim 1, characterized in that, The step of determining the frequency exclusion set corresponding to the active power grid filter compensation current based on the current spectrum information includes: The frequency exclusion width corresponding to each of the power grid harmonics is determined based on the harmonic amplitude of each of the power grid harmonics. Based on the frequency exclusion width and harmonic frequency of each of the power grid harmonics, the frequency exclusion zone corresponding to each of the power grid harmonics is determined. The set of frequency exclusion zones is determined based on the frequency exclusion zones corresponding to each of the aforementioned power grid harmonics.

3. The method according to claim 2, characterized in that, The step of determining the set of frequency exclusion zones based on the frequency exclusion zones corresponding to each of the power grid harmonics includes: Traverse the frequency exclusion zones corresponding to each of the power grid harmonics. For the current frequency exclusion zone, if the current frequency exclusion zone overlaps with the next frequency exclusion zone, then merge the current frequency exclusion zone and the next frequency exclusion zone into one frequency exclusion zone. After the traversal is complete, each frequency restricted area is added to the frequency restricted area set.

4. The method according to claim 1, characterized in that, The step of determining the excitation current sweep frequency information based on the frequency forbidden zone set and the sweep frequency band of the excitation current includes: Remove at least one target frequency from the frequency sweep of the excitation current to obtain at least one usable frequency range, wherein the target frequency is a frequency that is in the set of frequency forbidden zones, and each usable frequency range includes at least one usable frequency; Logarithmically spaced sampling is performed on each of the available frequency intervals to obtain multiple sampling frequencies corresponding to each available frequency interval. Arrange the sampling frequencies corresponding to each of the available frequency intervals to obtain the sampling frequency sequence corresponding to each of the available frequency intervals; Each available frequency range is used as an excitation current sweep frequency band, and each sampling frequency in the sampling frequency sequence corresponding to each available frequency range is used as multiple frequency points corresponding to each excitation current sweep frequency band.

5. The method according to claim 4, characterized in that, The step of performing logarithmically spaced sampling on each of the available frequency intervals to obtain multiple sampling frequencies corresponding to each available frequency interval includes: Obtain the upper and lower frequency limits of the available frequency range, and perform logarithmic operations on the upper and lower frequency limits respectively to obtain the logarithmic start point and logarithmic end point; Based on the upper and lower frequency limits of the available frequency range and the preset number of sampling points, the total number of sampling points in the available frequency range is determined. Based on the logarithmic start point, the logarithmic end point, and the total number of sampling points within the available frequency range, the available frequency range is sampled at equal intervals to obtain multiple sampling frequencies corresponding to the available frequency range.

6. The method according to claim 1, characterized in that, The step of performing excitation current frequency sweep according to the excitation current frequency sweep information and the path corresponding to the excitation current includes: Based on the rated output current RMS value of the energy storage converter, the current dispatch current RMS value, and the reserved current capacity, the current power margin is determined. The current power margin represents the remaining current margin that can be used for excitation current frequency sweep. Based on the current power margin, determine whether to perform an excitation current frequency sweep. If so, perform an excitation current frequency sweep according to the excitation current frequency sweep information and the path corresponding to the excitation current.

7. The method according to claim 6, characterized in that, The step of determining whether to perform an excitation current frequency sweep based on the current power margin includes: Compare the current power margin with the effective value of the excitation current required for frequency sweep of the excitation current; If the current power margin is greater than or equal to the effective value of the excitation current required for the excitation current frequency sweep, then the excitation current frequency sweep is determined to be performed, and the excitation current frequency sweep is performed according to the excitation current frequency sweep information and the path corresponding to the excitation current. If the current power margin is less than the effective value of the excitation current required for the excitation current frequency sweep, then the excitation current frequency sweep is postponed.

8. The method according to claim 2, characterized in that, The method further includes: Encrypted sampling is performed outside the left and right boundaries of the frequency exclusion zones corresponding to each of the power grid harmonics to obtain boundary reference values ​​of the frequency exclusion zones corresponding to each of the power grid harmonics. The boundary reference values ​​include the frequency, impedance amplitude, and phase angle of the left and right boundaries of the frequency exclusion zones corresponding to the power grid harmonics after sampling. Based on the boundary reference values ​​of the frequency forbidden zones corresponding to each of the power grid harmonics, interpolation is performed on each frequency point within the frequency forbidden zones corresponding to each of the power grid harmonics to determine the impedance amplitude and phase angle corresponding to each frequency point within the frequency forbidden zones corresponding to each of the power grid harmonics. Based on the impedance amplitude and phase angle of each frequency point within the frequency restricted area corresponding to each of the aforementioned power grid harmonics, a Nyquist plot is generated for frequency band analysis.

9. An electronic device, characterized in that, include: A processor and a memory, the memory storing machine-readable instructions executable by the processor, wherein when the electronic device is running, the processor executes the machine-readable instructions to perform the steps of the frequency processing method for the energy storage converter as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, performs the steps of the frequency processing method for the energy storage converter as described in any one of claims 1 to 8.

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