Output control method, controller and system of energy storage equipment

Abstract

The embodiment of the invention relates to the technical field of energy storage, and discloses an output control method of energy storage equipment, a controller and a system, and the output control method of the energy storage equipment comprises the steps: obtaining an AC signal outputted by the energy storage equipment; extracting a direct current component in the alternating current signal; obtaining a first target direct current component according to the direct current component and a pre-obtained direct current bias; performing first filtering processing on the first target direct current component to obtain a second target direct current component; the first filtering processing is to filter an alternating current signal in the first target direct current component; obtaining a target alternating current signal according to the second target direct current component and the alternating current signal; outputting a PWM control signal according to the target alternating current signal; therefore, the effect of inhibiting the direct-current component in the alternating-current electric signal is good, the accuracy of the finally output PWM control signal is high, and meanwhile, the operation stability of a power grid where the energy storage equipment is located is also improved.

Description

[0001] This application is a divisional application of a patent application with application date of November 27, 2024, application number 2024117208829, and invention name “Output control method, controller and system for energy storage equipment”. Technical Field

[0002] The embodiments of the present application relate to the field of energy storage technology, and in particular to an output control method, controller and system for an energy storage device. Background Art

[0003] At present, there is a DC component in the AC power output by energy storage devices such as energy storage converters and energy storage inverters. If the DC component of the current in the AC power is too large, it will cause other equipment in the power grid, such as transformers, to become magnetized, thereby causing the operating noise and mechanical vibration of the transformer to increase sharply and saturate, causing the equipment to heat up violently or even be damaged, and the power grid cannot be used normally.

[0004] In order to suppress the DC component in AC power, a common method in related technologies is to directly obtain the DC component of the energy storage device through a software algorithm and suppress it according to the obtained DC component. However, the suppression effect of the DC component is currently poor and cannot reach the ideal state. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide an output control method, controller and system for an energy storage device, so as to better suppress the DC component in the AC signal, and the accuracy of the final output PWM control signal is higher, while also improving the stability of the operation of the power grid where the energy storage device is located.

[0006] To solve the above technical problems, an embodiment of the present application provides an output control method for an energy storage device, which is applied to a controller of an output control system of an energy storage device, wherein the controller is connected to an input end and an output end of an energy storage device; the output control method for the energy storage device comprises: obtaining an AC signal output by the energy storage device; extracting a DC component in the AC signal; obtaining a first target DC component according to the DC component and a pre-acquired DC bias; performing a first filtering process on the first target DC component to obtain a second target DC component; the first filtering process is to filter out the AC signal in the first target DC component; obtaining a target AC signal according to the second target DC component and the AC signal; outputting a PWM control signal according to the target AC signal; the output control system of the energy storage device further comprises a low-pass filter; the low-pass filter is arranged between the input end of the controller and the output end of the energy storage device; obtaining the AC signal output by the energy storage device comprises: obtaining the AC signal output by the energy storage device through the low-pass filter; the AC signal is a signal after the low-pass filter performs a second filtering process, and the second filtering process is to filter out signals exceeding a preset frequency in the AC signal.

[0007] An embodiment of the present application also provides a controller, including: a sampling module, used to acquire an AC signal output by an energy storage device, extract a DC component from the AC signal, and obtain a first target DC component based on the DC component and a pre-acquired DC bias; a filtering module, used to perform a first filtering process on the first target DC component to obtain a second target DC component; the first filtering process is to filter out the AC signal in the first target DC component; a target AC signal acquisition module, used to acquire a target AC signal based on the second target DC component and the AC signal; a PWM output module, used to output a PWM control signal based on the target AC signal; a low-pass filter is also provided between the input end of the controller and the output end of the energy storage device; the acquisition of the AC signal output by the energy storage device includes: acquiring the AC signal output by the energy storage device through the low-pass filter; the AC signal is a signal after the low-pass filter performs a second filtering process, and the second filtering process is to filter out signals in the AC signal that exceed a preset frequency.

[0008] An embodiment of the present application further provides an output control system for an energy storage device, comprising: an energy storage device, a controller of the energy storage device as described above; an input end of the controller connected to an output end of the energy storage device.

[0009] In some embodiments, the first filtering process includes sliding filtering and Butterworth low-pass filtering; the first filtering process performed on the first target DC component to obtain the second target DC component includes: performing the sliding filtering process and the Butterworth low-pass filtering process on the first target DC component in sequence to obtain the second target DC component; the window length of the sliding filtering process is the number of sampling points of the entire cycle of the output current.

[0010] In some embodiments, before obtaining the first target DC component according to the DC component and the pre-acquired DC bias, it also includes: determining whether the energy storage device is in a non-working mode; if so, obtaining the DC bias; if not, executing the step of obtaining the first target DC component according to the DC component and the pre-acquired DC bias; obtaining the DC bias includes: obtaining all the deviation signals of the AC signal within a preset period range; and averaging all the deviation signals to obtain the DC bias.

[0011] In some embodiments, the method of obtaining a target AC power signal based on the second target DC component and the AC power signal includes: comparing the second target DC component with a preset given value to obtain a deviation signal; proportionally adjusting the deviation signal to obtain a proportional signal, and integrally adjusting the deviation signal to obtain an integral signal; superimposing the proportional signal and the integral signal to obtain a compensation DC component; and obtaining the target AC power signal based on the compensation DC component and the AC power signal.

[0012] In some embodiments, the output control system of the energy storage device also includes a phase-locked loop, and the controller is connected to the phase-locked loop; outputting a PWM control signal according to the target AC power signal includes: obtaining a coordinate transformation angle input to the phase-locked loop; transforming the target AC power signal from a stationary coordinate to a rotating coordinate according to the coordinate transformation angle to obtain a target electrical signal under the rotating coordinates; and obtaining the PWM control signal according to the target electrical signal under the rotating coordinates.

[0013] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0014] The present application obtains a first target DC component by comparing the extracted DC component with the DC bias, eliminates the bias error in the DC component, further eliminates the AC signal in the first target DC component through the first filtering process, and obtains a more accurate second target DC component. After that, the target AC signal is obtained according to the second target DC component and the AC signal; since the second target DC component has a high accuracy, the DC component in the AC signal can be eliminated well, and the DC component in the AC signal can be suppressed better. The target AC signal obtained has a high accuracy, so the PWM control signal output according to the target AC signal has a high accuracy. At the same time, since the present application has a good effect of eliminating the DC component in the AC signal, the stability of the power grid operation of the energy storage device is also improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0016] Figure 1 is a flow chart of an output control method of an energy storage device according to an embodiment of the present application;

[0017] Figure 2 is a structural schematic diagram of an output control system of an energy storage device according to an embodiment of the present application;

[0018] Figure 3 is a flow chart of an output control method of an energy storage device according to an embodiment of the present application;

[0019] Figure 4 is a flow chart of an output control method of an energy storage device according to an embodiment of the present application;

[0020] Figure 5 is a flow chart of an output control method of an energy storage device according to an embodiment of the present application;

[0021] Figure 6 is a structural schematic diagram of an output control system of an energy storage device according to an embodiment of the present application;

[0022] Figure 7 is a flow chart of an output control method of an energy storage device according to an embodiment of the present application;

[0023] Figure 8 is a structural schematic diagram of an output control system of an energy storage device according to an embodiment of the present application;

[0024] Fig. 9It is a schematic diagram of the structure of a controller according to an embodiment of the present application. DETAILED DESCRIPTION

[0025] As can be seen from the background art, the effect of suppressing DC components by software algorithms in related technologies is poor and cannot reach an ideal state.

[0026] After analysis and research, it was found that the reason why the software algorithm in the relevant technology has a poor effect in suppressing the DC component is that the common practice in the relevant technology is to directly extract the DC component of the energy storage device through the software algorithm, and suppress it according to the obtained DC component; however, since the DC component directly extracted from the three-phase current using the software method occupies a low proportion of the entire AC power, the accuracy of the small part of the DC component in the AC signal directly obtained by the software algorithm is low, and the obtained DC component has a large error, resulting in poor suppression of the DC component and failure to achieve the ideal state.

[0027] In order to solve the above technical problems, the present application obtains a first target DC component by comparing the extracted DC component with the DC bias, eliminates the bias error in the DC component, further eliminates the AC signal in the first target DC component through a first filtering process, and obtains a more accurate second target DC component. After that, the target AC signal is obtained according to the second target DC component and the AC signal; since the second target DC component has a high accuracy, the DC component in the AC signal can be eliminated well, and the DC component in the AC signal can be suppressed better. The target AC signal obtained has a high accuracy, so the pulse width modulation (PWM) control signal output according to the target AC signal has a high accuracy. At the same time, since the present application has a good effect of eliminating the DC component in the AC signal, it also improves the stability of the power grid operation where the energy storage device is located.

[0028] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. However, it will be appreciated by those skilled in the art that in the present application, many technical details are proposed in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present application can also be implemented. The division of the following embodiments is for the convenience of description, and the specific implementation of the present application should not be construed as any limitation, and the various embodiments can be combined and referenced with each other under the premise of no contradiction.

[0029] An embodiment of the present application relates to an output control method for an energy storage device. The specific flow chart of the output control method for the energy storage device is as follows: Figure 1 As shown, the following steps are included:

[0030] Step 101, obtaining an alternating current signal output by an energy storage device.

[0031] Specifically, this embodiment is applied to the controller of the output control system of the energy storage device, that is, the execution subject of this embodiment is the controller of the output control system of the energy storage device, such as Figure 2 , which is a schematic diagram of the structure of the output control system of the energy storage device. The input end of the controller 201 is connected to the output end of the energy storage device 202 , and the controller 201 can obtain the AC signal output by the energy storage device 202 .

[0032] Specifically, the energy storage device 202 is any one of the following: a converter, an inverter.

[0033] Specifically, the energy storage device 202 of this embodiment outputs three-phase alternating current, and the output control method of the energy storage device of this embodiment is used to suppress the DC component of each phase of the alternating current, so that the DC component of each item of alternating current is better suppressed, thereby improving the stability of the energy storage device 202 in the power grid.

[0034] Step 102: extract the DC component from the AC signal.

[0035] Specifically, the controller of this embodiment extracts the DC component from the AC signal to achieve the purpose of eliminating the DC component.

[0036] Step 103 : obtaining a first target DC component according to the DC component and the pre-acquired DC bias.

[0037] Specifically, after extracting the DC component from the AC signal, the controller calibrates the DC component according to the pre-acquired DC bias to obtain the first target DC component, thereby improving the accuracy of the acquired first target DC component.

[0038] Step 104: Perform a first filtering process on the first target DC component to obtain a second target DC component.

[0039] Specifically, the first filtering process is to filter out the AC signal in the first target DC component.

[0040] Specifically, the first filtering process includes sliding filtering and Butterworth low-pass filtering; performing the first filtering process on the first target DC component to obtain the second target DC component includes: performing sliding filtering and Butterworth low-pass filtering on the first target DC component in sequence to obtain the second target DC component.

[0041] Specifically, the sliding filter processing is performed by a sliding filter module in the controller, and the Butterworth low-pass filter processing is performed by a Butterworth low-pass filter in the controller.

[0042] Specifically, after obtaining the first target DC component, the controller inputs the first target DC component into the sliding filter module to further extract the DC component in the first target DC component and remove the AC pulsation component. The window length of the sliding filter module needs to be set to the number of sampling points of the entire cycle of the output current. The formula of the sliding filter module is: Where k is the number of current sampling times in the current cycle, I sample[i] is the first target DC component corresponding to the i-th sampling point, I filt is the DC component after sliding filtering. After that, the DC component after sliding filtering is input into the Butterworth second-order low-pass filter module to further eliminate the AC component.

[0043] The design of the Butterworth low-pass filter module in this embodiment is as follows:

[0044] (1) Set the normalized transfer function of the continuous second-order Butterworth low-pass filter to:

[0045]

[0046] (2) In the z-domain, the digital cutoff frequency is set to f d , the sampling frequency is set to f s , z = e sT , s = j2πf d ,

[0047] so

[0048] (3) Sampling bilinear transformation, then Substituting z into this, we have:

[0049]

[0050] (4) For the s domain, when the cutoff frequency of the analog input signal is set to f, then

[0051] s=jω=j2πf Formula ④

[0052] (5) According to equations ② and ③, we can deduce:

[0053]

[0054] According to formula ⑤, the cutoff angular frequency of the simulated Butterworth low-pass filter module is calculated as:

[0055]

[0056] (6) Substituting into equation ① for denormalization, the z-domain transfer function is:

[0057] After sorting, we get:

[0058]

[0059] After further sorting, we get:

[0060]

[0061] (7) Order

[0062]

[0063] Substituting into formula ⑦, we get:

[0064]

[0065] (8) Expanding formula ⑧ yields:

[0066] Y(z)(A 0 +A 1 z -1 +A 2 z -2 )=X(z)(B 0 +B 1 z -1 +B 2 z -2 )

[0067] Arranged:

[0068]

[0069] Re-order Then we have:

[0070] Y(z)=b 0 X(z)+b 1 X(z-1)+b 2 X(z-2)-a 1 Y(z-1)-a 2 Y(z-2) formula ⑨.

[0071] Step 105 : acquiring a target AC power signal according to the second target DC component and the AC power signal.

[0072] Specifically, after acquiring a relatively accurate second target DC component, the controller superimposes the second target DC component with the AC signal, that is, eliminates the DC component in the AC signal through the second target DC component.

[0073] Step 106: output a pulse width modulation control signal according to the target AC power signal.

[0074] Specifically, the output pulse width modulation (PWM) control signal is used to control the on and off of the power electronic switch in the power grid, thereby achieving AC to DC conversion.

[0075] This embodiment obtains a first target DC component by comparing the extracted DC component with the DC bias, eliminates the bias error in the DC component, further eliminates the AC signal in the first target DC component through the first filtering process, and obtains a more accurate second target DC component. After that, the target AC signal is obtained according to the second target DC component and the AC signal; since the second target DC component has a high accuracy, the DC component in the AC signal can be eliminated well, and the DC component in the AC signal can be suppressed better. The target AC signal obtained has a high accuracy, so the PWM control signal output according to the target AC signal has a high accuracy. At the same time, due to the good effect of eliminating the DC component in the AC signal, the present application also improves the stability of the operation of the power grid where the energy storage device is located.

[0076] Another embodiment of the present application relates to an output control method for an energy storage device. The specific flow chart of the output control method for the energy storage device is as follows: Figure 3 As shown, the following steps are included:

[0077] Step 301: Acquire an alternating current signal output by an energy storage device.

[0078] Step 302: extract the DC component from the AC signal.

[0079] Step 301 and step 302 of this embodiment are substantially the same as step 101 and step 102 of the previous embodiment, and will not be described again to avoid repetition.

[0080] Step 303: determine whether the energy storage device is in a non-operating mode.

[0081] If yes, the process proceeds to step 304 to obtain a DC bias; if no, the process proceeds to step 305 to obtain a first target DC component according to the DC component and the pre-acquired DC bias.

[0082] Step 304, obtaining a DC bias.

[0083] Specifically, obtaining the DC bias includes: obtaining all deviation signals of the AC signal within a preset period range; and averaging all the deviation signals to obtain the DC bias.

[0084] Specifically, in the non-working mode, since there is no AC current signal output, the signal output from the output end of the energy storage device has no AC and DC components. At this time, the signal obtained by sampling is the deviation signal. By obtaining all deviation signals within a preset period range, such as one period of the AC signal, in the non-working mode, the DC bias can be obtained by adding and averaging. The subsequent DC component can be calibrated through the DC bias.

[0085] Specifically, a DC bias is obtained when the energy storage device is in a non-operating mode, and when the energy storage device switches from the non-operating mode to the operating mode, a first target DC component is obtained according to the pre-acquired DC bias; even if the energy storage device switches from the operating mode to the non-operating mode multiple times, the DC bias used in the operating mode is obtained in the non-operating mode adjacent to the operating mode, which can ensure the accuracy of the DC bias, obtain a more accurate first target DC component, and further improve the effect of suppressing the DC component in the AC signal, thereby further improving the accuracy of the output PWM control signal. Specifically, the sampling module of the controller extracts the DC component in the operating mode, and the controller performs a DC component zero drift detection function in the non-operating mode. Specific method: Read the value of the DC component current sampling channel within the entire cycle of the AC current waveform and perform average value filtering. At this time, the value of the DC component current sampling channel does not include the AC signal and DC component, but only contains the deviation signal. The value of the deviation signal after average value filtering is recorded as the correction sampling bias, i.e., the DC bias. In the working mode, the DC component sampling value read from the DC component channel is subtracted from the DC bias calculated in the previous step, and the DC component current value, i.e., the first target DC component, is calculated based on the gain value.

[0086] Step 305 , obtaining a first target DC component according to the DC component and the pre-acquired DC bias.

[0087] Step 306: Perform a first filtering process on the first target DC component to obtain a second target DC component.

[0088] Step 307: Acquire a target AC power signal according to the second target DC component and the AC power signal.

[0089] Step 308: output a pulse width modulation control signal according to the target AC power signal.

[0090] Steps 305 to 308 of this embodiment are substantially the same as steps 103 to 106 of the previous embodiment, and will not be described again to avoid repetition.

[0091] This embodiment obtains a DC bias in a non-working mode, and uses the DC bias in a working mode to calibrate the DC component to obtain a more accurate first target DC component, thereby further improving the effect of suppressing the DC component in the AC signal, thereby further improving the accuracy of the output PWM control signal.

[0092] An embodiment of the present application further relates to an output control method for an energy storage device. The specific flow chart of the output control method for the energy storage device is as follows: Figure 4 As shown, the following steps are included:

[0093] Step 401: Acquire an alternating current signal output by an energy storage device.

[0094] Step 402: extract the DC component from the AC signal.

[0095] Step 403: Obtain a first target DC component according to the DC component and the pre-acquired DC bias.

[0096] Step 404: Perform a first filtering process on the first target DC component to obtain a second target DC component.

[0097] Steps 401 to 404 of this embodiment are substantially the same as steps 101 to 104 of the previous embodiment, and will not be described again to avoid repetition.

[0098] Step 405: Compare the second target DC component with a preset given value to obtain a deviation signal.

[0099] Step 406, proportionally adjust the deviation signal to obtain a proportional signal, integrally adjust the deviation signal to obtain an integral signal; superimpose the proportional signal and the integral signal to obtain a compensated DC component.

[0100] Specifically, after the first filtering process, this embodiment uses the filtered DC component as a feedback signal to obtain a second target DC component, and the second target DC component enters the PI (proportional-integral) regulation module of the controller. At this time, a given value is preset for the PI regulation module, and the given value is zero. After passing through the PI regulation module, the result of the PI regulation module is superimposed on the AC signal sampled from each phase to offset the DC component current in the sampled AC signal, thereby suppressing the DC component in the AC current.

[0101] Step 407: Acquire a target AC power signal according to the compensated DC component and the AC power signal.

[0102] Specifically, the above steps 405 to 407 are sub-steps of step 105 in the previous embodiment.

[0103] Step 408: output a pulse width modulation control signal according to the target AC power signal.

[0104] Step 408 of this embodiment is substantially the same as step 106 of the previous embodiment, and will not be described again to avoid repetition. The difference between step 407 and step 105 of the previous embodiment is that this embodiment obtains the target AC signal based on the compensated DC component and the AC signal, and obtains the target AC signal by obtaining the compensated DC component obtained after proportional-integral regulation, thereby improving the accuracy of obtaining the target AC signal.

[0105] After obtaining the second target DC component, this embodiment compares the second target DC component with a preset given value to obtain a deviation signal, performs proportional adjustment and integral adjustment on the deviation signal and then superimposes it to obtain a compensated DC component, and obtains the target AC signal based on the compensated DC component and the AC signal, thereby improving the accuracy of the obtained compensated DC component and further improving the accuracy of the output PWM control signal.

[0106] Another embodiment of the present application relates to an output control method for an energy storage device. The specific flow chart of the output control method for the energy storage device is as follows: Figure 5 As shown, the following steps are included:

[0107] Step 501: Acquire an alternating current signal output by an energy storage device through a low-pass filter.

[0108] Specifically, the AC signal is a signal after the low-pass filter performs the second filtering process, and the second filtering process is to filter out the signal exceeding the preset frequency in the AC signal. The energy storage device outputs the AC signal, and the second filtering process of the low-pass filter filters out the signal exceeding the preset frequency, i.e., the high-frequency signal.

[0109] Specifically, in this embodiment, the output control system of the corresponding energy storage device also includes a low-pass filter; the low-pass filter is arranged between the input end of the controller and the output end of the energy storage device; Figure 6 , which is a schematic diagram of the structure of the output control system of the energy storage device, the input end of the controller 201 is connected to the output end of the low-pass filter 203 , and the input end of the low-pass filter 203 is connected to the output end of the energy storage device 202 .

[0110] In this embodiment, a low-pass filter 203 is set between the input end of the controller 201 and the output end of the energy storage device 202. The low-pass filter 203 can filter the high-frequency signal in the AC signal, improve the accuracy of the acquired AC signal, thereby improving the accuracy of acquiring the DC component, and further improve the effect of suppressing the DC component in the AC signal. The accuracy of the output PWM control signal is also high.

[0111] Specifically, each phase current signal of this embodiment is filtered by a hardware low-pass filter circuit, the bandwidth of the filter circuit is generally set below 10 Hz, and a suitable signal gain coefficient is set according to the control accuracy to amplify the signal, and then sent to the sampling module of the controller for sampling.

[0112] Step 502: extract the DC component from the AC signal.

[0113] Step 503: Obtain a first target DC component according to the DC component and the pre-acquired DC bias.

[0114] Step 504: Perform a first filtering process on the first target DC component to obtain a second target DC component, wherein the first filtering process is to filter out the AC signal in the first target DC component.

[0115] Step 505 : acquiring a target AC power signal according to the second target DC component and the AC power signal.

[0116] Step 506: output a pulse width modulation control signal according to the target AC power signal.

[0117] Steps 502 to 506 of this embodiment are substantially the same as steps 102 to 106 of the previous embodiment, and will not be described again to avoid repetition.

[0118] It should be noted that the low-pass filter of this embodiment is hardware. This embodiment eliminates the DC component in the AC signal by hardware plus software, and has a better effect of suppressing the DC component in the AC signal. The accuracy of the target AC signal obtained is higher, so the accuracy of the PWM control signal output according to the target AC signal is higher.

[0119] Another embodiment of the present application relates to an output control method for an energy storage device. The specific flow chart of the output control method for the energy storage device is as follows: Figure 7 As shown, the following steps are included:

[0120] Step 601, obtaining an alternating current signal output by an energy storage device.

[0121] Step 602: extract the DC component from the AC signal.

[0122] Step 603: Obtain a first target DC component according to the DC component and the pre-acquired DC bias.

[0123] Step 604: Perform a first filtering process on the first target DC component to obtain a second target DC component.

[0124] Step 605: Acquire a target AC power signal according to the second target DC component and the AC power signal.

[0125] Steps 601 to 605 of this embodiment are substantially the same as steps 101 to 105 of the previous embodiment, and will not be described again to avoid repetition.

[0126] Step 606, obtaining the coordinate transformation angle of the phase-locked loop input.

[0127] Step 607 , transform the target AC electric signal from a stationary coordinate to a rotating coordinate according to the coordinate transformation angle, to obtain a target electric signal under the rotating coordinate.

[0128] Step 608 , obtaining a pulse width modulation control signal according to the target electrical signal under the rotating coordinates.

[0129] Specifically, the above steps 606 to 608 are sub-steps of step 106 in the previous embodiment.

[0130] Specifically, the output control system of the corresponding energy storage device in this embodiment also includes a phase-locked loop, and the controller is connected to the phase-locked loop; Figure 8 As shown, it is a structural diagram of the output control system of the energy storage device. The input end of the controller 201 is connected to the output end of the low-pass filter 203, the input end of the low-pass filter 203 is connected to the output end of the energy storage device 202, and the controller 201 is also connected to the phase-locked loop 204.

[0131] The coordinate transformation angle in this embodiment is provided by a phase-locked loop. The phase-locked loop provides the coordinate transformation angle, and the target AC electric signal is transformed from a stationary coordinate to a rotating coordinate according to the coordinate transformation angle to obtain a target electric signal under the rotating coordinate. The target electric signal is output to a PWM wave generation control module through a current inner loop controller. The PWM wave generation control module obtains a PWM control signal according to the target electric signal under the rotating coordinate, thereby providing a PWM control signal for power electronic switches in the power grid, such as metal-oxide-semiconductor field-effect transistors (MOSFET) and insulated gate bipolar transistors (IGBT), and further controlling the rapid on and off of the power electronic switches in the power grid to realize the AC-DC conversion process.

[0132] It should be noted that the output control method of the energy storage device of the present application is used to simulate the rated load condition using simulation software. During the simulation process, a DC component of the current is introduced into the AC signal output by the energy storage device. The simulation results of turning on and off the DC component suppression are used for comparison. The data show that the proportion of the DC component in the total harmonic distortion (THD) of the working condition in which the output control method of the energy storage device of the present application is added is greatly reduced, and the actual measurement is consistent with the simulation results, which proves that this method has a significant effect on suppressing the DC component in the AC current.

[0133] The following are the details of the simulation data:

[0134] Serial number Load conditions Is there a DC component control? Percentage of DC component in THD 1 Rated load no 1.08％ 2 Rated load yes 0.07％

[0135] On the other hand, the embodiment of the present application further provides a controller, such as Fig. 9 , which is a schematic diagram of the structure of the controller, the controller 201 includes: a sampling module 2011 , a filtering module 2012 , a target AC signal acquisition module 2013 , and a pulse width modulation output module 2014 .

[0136] Specifically, the sampling module 2011 is used to obtain the AC signal output by the energy storage device 202, extract the DC component in the AC signal, and obtain the first target DC component according to the DC component and the pre-acquired DC bias.

[0137] Specifically, a low-pass filter 203 is further provided between the input end of the controller 201 and the output end of the energy storage device 202; the sampling module 2011 of this embodiment is connected to the low-pass filter 203, and the low-pass filter 203 is connected to the output end of the energy storage device 202; in this embodiment, the AC signal output by the energy storage device 202 is obtained, specifically: the AC signal output by the energy storage device 202 is obtained through the low-pass filter 203; the AC signal is a signal subjected to a second filtering process by low-pass filtering, and the second filtering process is to filter out signals exceeding a preset frequency in the AC signal.

[0138] Specifically, the sampling module 2011 is also used to determine whether the energy storage device 202 is in a non-working mode before obtaining the first target DC component based on the DC component and the pre-acquired DC bias; if so, obtain the DC bias; if not, execute the step of obtaining the first target DC component based on the DC component and the pre-acquired DC bias; wherein obtaining the DC bias includes: obtaining all DC components of the AC signal within a preset period range; and averaging all DC components to obtain the DC bias.

[0139] The filtering module 2012 is used to perform a first filtering process on the first target DC component to obtain a second target DC component; the first filtering process is to filter out the AC signal in the first target DC component.

[0140] Specifically, the filtering module 2012 includes a sliding filtering module 20121 and a Butterworth low-pass filtering module 20122 .

[0141] The target AC power signal acquisition module 2013 is configured to acquire a target AC power signal according to the second target DC component and the AC power signal.

[0142] The pulse width modulation output module 2014 is used to output a PWM control signal according to the target AC power signal.

[0143] Specifically, the pulse width modulation output module 2014 includes a coordinate transformation module 20141 and a pulse width modulation wave control module 20142; the coordinate transformation module 20141 is used to obtain the coordinate transformation angle input by the phase-locked loop 204, and transform the target AC electric signal from a stationary coordinate to a rotating coordinate according to the coordinate transformation angle to obtain a target electric signal under the rotating coordinate; the pulse width modulation wave control module 20142 is used to obtain a PWM control signal according to the target electric signal under the rotating coordinate.

[0144] Specifically, the target AC signal acquisition module 2013 of the present embodiment includes: a proportional-integral adjustment module 20131 and a signal superposition module 20132; the proportional-integral adjustment module 20131 is used to compare the second target DC component with a preset given value to obtain a deviation signal, proportionally adjust the deviation signal to obtain a proportional signal, integrally adjust the deviation signal to obtain an integral signal, and superimpose the proportional signal and the integral signal to obtain a compensated DC component; the signal superposition module 20132 is used to obtain the target AC signal based on the compensated DC component and the AC signal.

[0145] The controller 201 of this embodiment obtains a first target DC component by comparing the extracted DC component with the DC bias, eliminates the bias error in the DC component, further eliminates the AC signal in the first target DC component through the first filtering process, and obtains a more accurate second target DC component. After that, the target AC signal is obtained according to the second target DC component and the AC signal; since the accuracy of the second target DC component is relatively high, the DC component in the AC signal can be eliminated well, and the effect of suppressing the DC component in the AC signal is better, and the accuracy of the obtained target AC signal is higher, so the accuracy of the PWM control signal output according to the target AC signal is higher. At the same time, due to the better effect of eliminating the DC component in the AC signal, the present application also improves the stability of the operation of the power grid where the energy storage device 202 is located.

[0146] On the other hand, the present application provides an output control system for an energy storage device. The structural diagram of the output control system for the energy storage device is as follows: Figure 2 As shown, it includes: an energy storage device 202 and a controller 201 in the previous controller embodiment; the input end of the controller 201 is connected to the output end of the energy storage device 202 .

[0147] In this embodiment, the controller 201 obtains the first target DC component according to the extracted DC component and the DC bias, eliminates the bias error in the DC component, further eliminates the AC signal in the first target DC component through the first filtering process, and obtains a more accurate second target DC component. After that, the target AC signal is obtained according to the second target DC component and the AC signal, which can well suppress the DC component in the AC signal, and the output PWM control signal has a high accuracy. At the same time, due to the good effect of eliminating the DC component in the AC signal, the present application also improves the stability of the operation of the power grid where the energy storage device 202 is located.

[0148] Another embodiment of the present application also relates to an output control system of an energy storage device. The structural diagram of the output control system of the energy storage device is as follows: Figure 6 As shown, it includes: a controller 201, an energy storage device 202, and a low-pass filter 203; the input end of the controller 201 is connected to the output end of the low-pass filter 203, and the input end of the low-pass filter 203 is connected to the output end of the energy storage device 202.

[0149] In this embodiment, a low-pass filter 203 is set between the input end of the controller 201 and the output end of the energy storage device 202. The low-pass filter 203 can filter the high-frequency signal in the AC signal, improve the accuracy of the acquired AC signal, thereby improving the accuracy of the acquired DC component, and further improve the effect of suppressing the DC component in the AC signal. The accuracy of the output PWM control signal is also high.

[0150] Another embodiment of the present application relates to an output control system of an energy storage device. The structural diagram of the output control system of the energy storage device is as follows: Figure 8 As shown, it includes: a controller 201, an energy storage device 202, a low-pass filter 203, and a phase-locked loop 204; the input end of the controller 201 is connected to the output end of the low-pass filter 203, the input end of the low-pass filter 203 is connected to the output end of the energy storage device 202, and the controller 201 is also connected to the phase-locked loop 204.

[0151] The coordinate transformation angle in this embodiment is provided by the phase-locked loop 204. The coordinate transformation angle is provided by the phase-locked loop 204, and the target AC electric signal is transformed from a stationary coordinate to a rotating coordinate according to the coordinate transformation angle to obtain a target electric signal under the rotating coordinates, and a PWM control signal is obtained according to the target electric signal under the rotating coordinates.

[0152] The division of various components above is only for clear description. When implemented, they can be combined into one component or some components can be split and decomposed into multiple components. As long as they include the same logical relationship, they are all within the protection scope of this application.

[0153] Those skilled in the art will appreciate that the above embodiments are specific embodiments for implementing the present application, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present application.

Claims

1. An output control method for an energy storage device, characterized in that: A controller applied to an output control system of an energy storage device, wherein an input end of the controller is connected to an output end of the energy storage device; The output control method of the energy storage device comprises: Acquiring an alternating current signal output by the energy storage device; extracting a DC component from the AC signal; Obtaining a first target DC component according to the DC component and a pre-acquired DC bias; Performing a first filtering process on the first target DC component to obtain a second target DC component; the first filtering process is to filter out an AC signal in the first target DC component; Acquire a target AC power signal according to the second target DC component and the AC power signal; Outputting a PWM control signal according to the target AC power signal; The output control system of the energy storage device further includes a low-pass filter; the low-pass filter is arranged between the input end of the controller and the output end of the energy storage device; the step of obtaining the alternating current signal output by the energy storage device includes: The alternating current signal output by the energy storage device is obtained through the low-pass filter; the alternating current signal is a signal after the low-pass filter performs a second filtering process, and the second filtering process is to filter out signals exceeding a preset frequency in the alternating current signal.

2. The output control method of the energy storage device according to claim 1, characterized in that: The first filtering process includes sliding filtering and Butterworth low-pass filtering; the first filtering process performed on the first target DC component to obtain the second target DC component includes: performing the sliding filtering process and the Butterworth low-pass filtering process on the first target DC component in sequence to obtain the second target DC component; the window length of the sliding filtering process is the number of sampling points of the entire cycle of the output current.

3. The output control method of the energy storage device according to claim 1 or 2, characterized in that: Before obtaining the first target DC component according to the DC component and the pre-acquired DC bias, the method further includes: Determine whether the energy storage device is in a non-operating mode; if so, obtain the DC bias; if not, execute the step of obtaining a first target DC component according to the DC component and the pre-acquired DC bias; The obtaining of the DC bias comprises: Acquire all deviation signals of the alternating current signal within a preset period range; The DC bias is obtained by averaging all the deviation signals.

4. The output control method of the energy storage device according to claim 1, characterized in that: The step of acquiring a target AC power signal according to the second target DC component and the AC power signal includes: Comparing the second target DC component with a preset given value to obtain a deviation signal; Proportional adjustment is performed on the deviation signal to obtain a proportional signal, and integral adjustment is performed on the deviation signal to obtain an integral signal; and the proportional signal and the integral signal are superimposed to obtain a compensated DC component; The target AC power signal is acquired according to the compensated DC component and the AC power signal.

5. The output control method of the energy storage device according to claim 1, characterized in that: The output control system of the energy storage device further includes a phase-locked loop, and the controller is connected to the phase-locked loop; the outputting of a PWM control signal according to the target AC power signal includes: Obtaining a coordinate transformation angle of the phase-locked loop input; Transforming the target AC electric signal from a stationary coordinate to a rotating coordinate according to the coordinate transformation angle to obtain a target electric signal under the rotating coordinate; The PWM control signal is obtained according to the target electrical signal under the rotating coordinates.

6. A controller, characterized in that: include: A sampling module, used to obtain an alternating current signal output by an energy storage device, extract a direct current component from the alternating current signal, and obtain a first target direct current component according to the direct current component and a pre-acquired direct current bias; A filtering module, configured to perform a first filtering process on the first target DC component to obtain a second target DC component; the first filtering process is to filter out an AC signal in the first target DC component; a target AC power signal acquisition module, configured to acquire a target AC power signal according to the second target DC component and the AC power signal; A PWM output module, used for outputting a PWM control signal according to the target AC power signal; A low-pass filter is also provided between the input end of the controller and the output end of the energy storage device; the acquisition of the AC signal output by the energy storage device includes: acquiring the AC signal output by the energy storage device through the low-pass filter; the AC signal is the signal after the low-pass filter performs a second filtering process, and the second filtering process is to filter out the signal exceeding a preset frequency in the AC signal.

7. The controller according to claim 6, characterized in that: The target AC signal acquisition module comprises: a proportional-integral regulating module, configured to compare the second target DC component with a preset given value to obtain a deviation signal, proportionally regulate the deviation signal to obtain a proportional signal, integrally regulate the deviation signal to obtain an integral signal, and superimpose the proportional signal and the integral signal to obtain a compensation DC component; A signal superposition module is used to obtain a target AC signal according to the compensated DC component and the AC signal.

8. The controller according to claim 6, characterized in that: The PWM output module includes a coordinate transformation module and a PWM wave control module; The coordinate transformation module is used to obtain the coordinate transformation angle of the phase-locked loop input, and transform the target AC electric signal from a stationary coordinate to a rotating coordinate according to the coordinate transformation angle to obtain the target electric signal under the rotating coordinate; The PWM wave generation control module is used to obtain the PWM control signal according to the target electrical signal under the rotating coordinates.

9. An output control system for an energy storage device, characterized in that: include: An energy storage device, a controller for the energy storage device as claimed in any one of claims 6 to 8; the input end of the controller is connected to the output end of the energy storage device.

10. The output control system of the energy storage device according to claim 9, characterized in that: The output control system of the energy storage device also includes a low-pass filter and a phase-locked loop; the low-pass filter is arranged between the input end of the controller and the output end of the energy storage device, and the controller is also connected to the phase-locked loop.

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