Power-off Detection Method, System, Device and Storage Medium Based on Household Energy Storage System

Abstract

The present invention discloses a power failure detection method, system, device and storage medium based on a household energy storage system. The method obtains a third voltage signal value by performing coordinate transformation, decoupling and filtering calculations on the collected three-phase grid voltage signals, then obtains a first difference according to the third voltage signal value, selects a first detection threshold according to the first difference and the current third voltage signal value, and finally determines whether the grid of the household energy storage system has a power failure according to the first difference and the first detection threshold, which can reduce the amount of data processing, speed up the detection speed, and improve the detection accuracy and adaptability; furthermore, it can ensure that when the grid has an abnormal power failure, the machine can be quickly and accurately identified and switched to off-grid power supply to ensure the stable power supply of the electrical equipment at the Backup port. The present invention can be widely applied to the technical field of power failure detection of household energy storage systems.

Description

Technical Field

[0001] The present invention relates to the technical field of power-off detection for household energy storage systems, and in particular to a power-off detection method, system, device and storage medium based on a household energy storage system. Background Art

[0002] The photovoltaic energy storage integrated machine has an off-grid power supply function. How to quickly detect when the power grid is abnormal, so as to control the photovoltaic energy storage integrated machine to switch to off-grid operation and ensure the continuous power supply of the electrical equipment at the Backup port has become an important research topic. There are two existing power grid power-off detection methods. The first detection method is to detect whether the power grid voltage and power grid frequency exceed the safety regulation requirement threshold for a continuous period of time. Although this method is stable and reliable and not prone to false detection, the detection time is long, which is likely to cause the electrical equipment at the Backup port to power off and shut down. The second detection method is to record each sampling value within a complete cycle of the power grid voltage. By comparing the current power grid voltage sampling value with the power grid voltage sampling value one cycle ago, when the difference exceeds a certain detection threshold, it can be determined that the power grid has lost power, and then the machine can be quickly switched to the off-grid power supply mode. Although this method has a fast detection speed, it has a large amount of data to process, a long execution time, is prone to false detection due to sampling interference, and it is difficult to accurately detect and determine when only one phase of the three-phase power grid has lost power. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a power-off detection method, system, device and storage medium based on a household energy storage system.

[0004] The technical solution adopted by the present invention is as follows:

[0005] On the one hand, an embodiment of the present invention includes a power-off detection method based on a household energy storage system, comprising:

[0006] Collecting three-phase power grid voltage signals;

[0007] Transforming the three-phase power grid voltage signals from a three-phase static coordinate system to a two-phase static coordinate system to obtain a first voltage signal and a second voltage signal;

[0008] Transforming the first voltage signal and the second voltage signal from the two-phase static coordinate system to a positive-sequence two-phase rotating coordinate system to obtain a first positive-sequence voltage signal and a second positive-sequence voltage signal;

[0009] Transforming the first voltage signal and the second voltage signal from the two-phase static coordinate system to a negative-sequence two-phase rotating coordinate system to obtain a first negative-sequence voltage signal and a second negative-sequence voltage signal;

[0010] Perform decoupling and filtering calculations on the first positive-sequence voltage signal, the second positive-sequence voltage signal, the first negative-sequence voltage signal, and the second negative-sequence voltage signal to obtain a third voltage signal value;

[0011] Obtain a first value and a second value, where the first value is the current third voltage signal value, and the second value is the third voltage signal value before a first preset time period;

[0012] Obtain a first difference according to the first value and the second value;

[0013] Select a first detection threshold according to the third voltage signal value and the first difference;

[0014] Judge whether the grid of the household energy storage system is powered off according to the first difference and the first detection threshold.

[0015] Further, the step of transforming the three-phase grid voltage signal from the three-phase stationary coordinate system to the two-phase stationary coordinate system to obtain a first voltage signal and a second voltage signal is executed by the following formula:

[0016]

[0017] In the formula, U a , U b , U c are the three-phase grid voltage signals obtained by acquisition, U af is the first voltage signal, and U bt is the second voltage signal.

[0018] Further, the step of transforming the first voltage signal and the second voltage signal from the two-phase stationary coordinate system to the positive-sequence two-phase rotating coordinate system to obtain a first positive-sequence voltage signal and a second positive-sequence voltage signal is executed by the following formula:

[0019]

[0020] In the formula, U af is the first voltage signal, U bt is the second voltage signal, U dpos is the first positive-sequence voltage signal, U qpos is the second positive-sequence voltage signal, and θ is the angle between the two-phase stationary coordinate system and the positive-sequence two-phase rotating coordinate system.

[0021] Further, the step of transforming the first voltage signal and the second voltage signal from the two-phase stationary coordinate system to the negative-sequence two-phase rotating coordinate system to obtain a first negative-sequence voltage signal and a second negative-sequence voltage signal is executed by the following formula:

[0022]

[0023] Wherein, U af is the first voltage signal, U bt is the second voltage signal, U dneg is the first negative sequence voltage signal, U qneg is the second negative sequence voltage signal, and θ is the angle between the two-phase stationary coordinate system and the negative sequence two-phase rotating coordinate system.

[0024] Further, the obtaining of the first difference according to the first value and the second value is specifically:

[0025] Subtracting the second value from the first value to obtain the first difference.

[0026] Further, the step of selecting the first detection threshold according to the third voltage signal value and the first difference is performed by the following formula:

[0027]

[0028] Wherein, U threshold represents the first detection threshold, U d represents the third voltage signal value, U detla represents the first difference.

[0029] Further, the step of determining whether the grid of the household energy storage system is powered off according to the first difference and the first detection threshold includes:

[0030] Comparing the absolute value of the first difference with the first detection threshold;

[0031] If the absolute value of the first difference exceeds the first detection threshold within a continuous first time period, it is determined that the grid of the household energy storage system is powered off.

[0032] On the other hand, an embodiment of the present invention includes a power-off detection system based on a household energy storage system, including:

[0033] An acquisition module for acquiring three-phase grid voltage signals;

[0034] A first transformation module for transforming the three-phase grid voltage signals from the three-phase stationary coordinate system to the two-phase stationary coordinate system to obtain a first voltage signal and a second voltage signal;

[0035] A second transformation module for transforming the first voltage signal and the second voltage signal from the two-phase stationary coordinate system to the positive sequence two-phase rotating coordinate system to obtain a first positive sequence voltage signal and a second positive sequence voltage signal;

[0036] A third transformation module, configured to transform the first voltage signal and the second voltage signal from a two-phase stationary coordinate system to a negative-sequence two-phase rotating coordinate system, so as to obtain a first negative-sequence voltage signal and a second negative-sequence voltage signal;

[0037] A calculation module, configured to perform decoupling and filtering calculations on the first positive-sequence voltage signal, the second positive-sequence voltage signal, the first negative-sequence voltage signal, and the second negative-sequence voltage signal to obtain a third voltage signal value;

[0038] A first acquisition module, configured to acquire a first value and a second value, where the first value is the current third voltage signal value, and the second value is the third voltage signal value before a first preset time period;

[0039] A second acquisition module, configured to acquire a first difference according to the first value and the second value;

[0040] A selection module, configured to select a first detection threshold according to the third voltage signal value and the first difference;

[0041] A judgment module, configured to judge whether the power grid of the household energy storage system is powered off according to the first difference and the first detection threshold.

[0042] On the other hand, an embodiment of the present invention includes a power-off detection device based on a household energy storage system, including:

[0043] At least one processor;

[0044] At least one memory, configured to store at least one program;

[0045] When the at least one program is executed by the at least one processor, the at least one processor implements the power-off detection method based on the household energy storage system.

[0046] On the other hand, an embodiment of the present invention includes a computer-readable storage medium, on which a program executable by a processor is stored, and the program executable by the processor is used to implement the power-off detection method based on the household energy storage system when being executed by the processor.

[0047] The beneficial effects of the present invention are:

[0048] In the present invention, the three-phase grid voltage signals collected are subjected to coordinate transformation, decoupling, and filtering calculations to obtain the value of the third voltage signal. Then, the first difference is obtained based on the value of the third voltage signal. Next, the first detection threshold is selected according to the first difference and the current value of the third voltage signal. Finally, it is determined whether the grid of the household energy storage system has lost power based on the first difference and the first detection threshold. This can reduce the amount of data processing, speed up the detection speed, and improve the detection accuracy and adaptability. Furthermore, it can ensure that when the grid abnormally loses power, the machine can be quickly and accurately identified and switched to off-grid power supply to ensure the stable power supply of the electrical equipment at the Backup port.

[0049] Additional aspects and advantages of the present invention will be given in part in the following description, and part will become obvious from the following description or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0051] Figure 1 is a flowchart of the steps of the power-off detection method based on a household energy storage system according to an embodiment of the present invention;

[0052] Figure 2 is another flowchart of the power-off detection method based on a household energy storage system according to an embodiment of the present invention;

[0053] Figure 3 is a schematic diagram of the Clark transformation of the three-phase grid voltage signals according to an embodiment of the present invention;

[0054] Figure 4 is a schematic diagram of the Park transformation of the three-phase grid voltage signals according to an embodiment of the present invention;

[0055] Figure 5 is an actual effect diagram of detecting abnormal grid power-off and switching to off-grid operation according to an embodiment of the present invention;

[0056] Figure 6 is a schematic structural diagram of the power-off detection device based on a household energy storage system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0057] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0058] In the description of the present invention, it should be understood that with regard to the orientation description, for example, the orientation or positional relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0059] In the description of the present invention, the meaning of "several" is one or more, the meaning of "multiple" is more than two, and understandings such as "greater than", "less than", "exceeding", etc. do not include the present number. If there is a description of first, second, third, etc., it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or the sequence relationship of the indicated technical features.

[0060] In the description of the present invention, unless otherwise clearly defined, words such as "set", "install", "connect", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meaning of the above words in the present invention in combination with the specific content of the technical solution.

[0061] Referring to Figure 1 and Figure 2 , an embodiment of the present invention provides a power-off detection method based on a household energy storage system, including:

[0062] S100. Collect three-phase grid voltage signals;

[0063] S200. Transform the three-phase grid voltage signals from the three-phase stationary coordinate system to the two-phase stationary coordinate system to obtain a first voltage signal and a second voltage signal;

[0064] S300. Transform the first voltage signal and the second voltage signal from the two-phase stationary coordinate system to the positive-sequence two-phase rotating coordinate system to obtain a first positive-sequence voltage signal and a second positive-sequence voltage signal;

[0065] S400. Transform the first voltage signal and the second voltage signal from the two-phase stationary coordinate system to the negative-sequence two-phase rotating coordinate system to obtain a first negative-sequence voltage signal and a second negative-sequence voltage signal;

[0066] S500. Perform decoupling and filtering calculations on the first positive-sequence voltage signal, the second positive-sequence voltage signal, the first negative-sequence voltage signal, and the second negative-sequence voltage signal to obtain a third voltage signal value;

[0067] S600. Obtain a first value and a second value, where the first value is the current third voltage signal value, and the second value is the third voltage signal value before the first preset duration;

[0068] S700. Obtain a first difference according to the first value and the second value;

[0069] S800. Select a first detection threshold according to the third voltage signal value and the first difference value.

[0070] S900. Determine whether the grid of the household energy storage system has lost power according to the first difference value and the first detection threshold.

[0071] In this embodiment, a three-phase grid voltage signal is collected by a photovoltaic energy storage inverter, and the collected three-phase grid voltage signal is denoted as U a , U b , U c . Then, according to the Clark transformation, the three-phase grid voltage signals U a , U b , U c are transformed from the three-phase stationary voltage coordinate system to the two-phase stationary voltage coordinate system to obtain a first voltage signal U af and a second voltage signal U bt . Then, according to the Park transformation, the first voltage signal U af and the second voltage signal U bt are transformed from the two-phase stationary voltage coordinate system to the positive-sequence two-phase rotating coordinate system to obtain a first positive-sequence voltage signal U dpos and a second positive-sequence voltage signal U qpos ; at the same time, according to the Park transformation, the first voltage signal U af and the second voltage signal U bt are transformed from the two-phase stationary voltage coordinate system to the negative-sequence two-phase rotating coordinate system to obtain a first negative-sequence voltage signal U dneg and a second negative-sequence voltage signal U qneg . Then, the first positive-sequence voltage signal U dpos , the second positive-sequence voltage signal U qpos , the first negative-sequence voltage signal U dneg , and the second negative-sequence voltage signal U qneg are calculated through decoupling and filtering to obtain a third voltage signal value U d and a fourth voltage signal value U q . In this embodiment, the third voltage signal value U d within 3 ms is recorded and saved, and then the current third voltage signal value U d is compared with the third voltage signal value U d 3 ms ago to obtain a first difference value U detla . Finally, according to the third voltage signal value U d and the first difference value U detla , a first detection threshold U threshold is selected; finally, according to the first difference value U detla and the first detection threshold U thresholdDetermine whether the grid of the household energy storage system has lost power. The embodiments of the present invention can reduce the amount of data processing, speed up the detection speed, improve the detection accuracy and adaptability; and then can ensure that the machine can quickly and accurately identify when the grid abnormally loses power and switch to off-grid power supply to ensure the stable power supply of the electrical equipment at the Backup port.

[0072] Specifically, in this embodiment, through the Clark transformation, the three-phase grid voltage signals U a 、U b 、U c are transformed from the three-phase stationary coordinate system to the αβ two-phase stationary coordinate system to obtain the first voltage signal U af and the second voltage signal U bt . Specifically, as Figure 3 shown, the amplitudes of the three-phase grid voltages are equal, and the phases are 120 degrees apart from each other. An αβ two-phase stationary coordinate system is established. Place U a on the α coordinate axis. Since the β coordinate axis and the α coordinate axis are 90 degrees apart, map U a 、U b 、U c onto the β coordinate axis and the α coordinate axis respectively to obtain the first voltage signal U af and the second voltage signal U bt . The specific calculation formula is as follows:

[0073]

[0074] In Equation 1, U a 、U b 、U c are the three-phase grid voltage signals collected, U af is the first voltage signal, and U bt is the second voltage signal.

[0075] Referring to Figure 4 , in this embodiment, after obtaining the first voltage signal U af and the second voltage signal U bt , further through the Park transformation, the first voltage signal U af and the second voltage signal U bt are transformed from the αβ two-phase stationary voltage coordinate system to the DQ two-phase rotating coordinate system to obtain the first positive-sequence voltage signal U dpos , the second positive-sequence voltage signal U qpos , the first negative-sequence voltage signal U dneg and the second negative-sequence voltage signal U qneg . Specifically, as Figure 4As shown, in the αβ two-phase stationary coordinate system, the grid voltage signal is constantly rotating while the coordinate axes are stationary; in the DQ two-phase rotating coordinate system, the coordinate axes and the grid voltage signal rotate together. By controlling the rotational angular velocity ω of the rotating coordinate system, the DQ coordinate system rotates to an angle θ. At this time, the projection U of the grid voltage signal on the Q axis q is 0, and in this way, the projection U of the grid voltage signal on the D axis can be obtained d . The specific calculation formula is as follows:

[0076]

[0077]

[0078] In the formula, U af is the first voltage signal, U bt is the second voltage signal, U dpos is the first positive-sequence voltage signal, U qpos is the second positive-sequence voltage signal; U dneg is the first negative-sequence voltage signal, U qneg is the second negative-sequence voltage signal; θ is the angle between the two-phase stationary coordinate system and the positive-sequence two-phase rotating coordinate system.

[0079] In this embodiment, there is a coupling relationship in the voltage signals obtained through Park transformation. And when the three-phase power grid is unbalanced, the voltage signal values after coordinate transformation will carry a large AC signal component, affecting signal detection. Therefore, it is necessary to further perform decoupling and filtering processing on the first positive-sequence voltage signal U dpos , the second positive-sequence voltage signal U qpos and the first negative-sequence voltage signal U dneg , the second negative-sequence voltage signal U qneg to obtain the third voltage signal value U d and the fourth voltage signal value U q . The specific calculation process is as follows:

[0080] U dcouppos =U dpos -U dfilterpreneg ×cos2θ - U qfilterpreneg ×sin2θ;

[0081] U qcouppos =U qpos -U dfilterpreneg ×cos2θ - U qfilterpreneg ×sin2θ;

[0082] U dcouppneg =U dneg -U dfilterprepos ×cos2θ - U qfilterprepos ×sin2θ;

[0083] U qcouppneg = U qneg - U dfilterprepos × cos2θ - U qfilterprepos × sin2θ;

[0084] U dfilterpos = U dfilterprepos × 0.9 + U dcouppos × 0.1;

[0085] U dfilterprepos = U dfilterpos ;

[0086] U qfilterpos = U qfilterprepos × 0.9 + U qcouppos × 0.1;

[0087] U qfilterprepos = U qfilterpos ;

[0088] U dfilterneg = U dfilterpreneg × 0.9 + U dcoupneg × 0.1;

[0089] U dfilterpreneg = U dfilterpneg ;

[0090] U qfilterneg = U qfilterpreneg × 0.9 + U qcoupneg × 0.1;

[0091] U qfilterpreneg = U qfilterpneg ;

[0092] U d = U dcouppos ;

[0093] U q = U qcouppos .

[0094] In this embodiment, the U value within 3 ms is recorded and saved, and then the current U value is compared with the U value 3 ms ago to obtain the first difference U. Specifically, the current U value is subtracted from the U value 3 ms ago to obtain the first difference U, and the calculation formula is: U = U - U. d value, and then the current U d value and the U d value 3 ms ago are compared to obtain the first difference U detla . Specifically, subtracting the U d value 3 ms ago from the current U d value gives the first difference U detla , and the calculation formula is: U detla = U d(当前) - U d(3ms前) .

[0095] In this embodiment, the first difference U is obtained detla After that, based on the value of U d value and the first difference U detla select the first detection threshold U threshold , specifically, the selection formula is:

[0096]

[0097] It can be seen from the formula that the first detection threshold U threshold is determined by the first difference U detla and U detla .

[0098] In this embodiment, after determining the first detection threshold U threshold , further compare the first difference U detla with the first detection threshold U threshold . If the absolute value of the first difference U detla exceeds the first detection threshold U threshold within a continuous first time period, it is determined that the grid power of the household energy storage system is lost. Specifically, in this embodiment, if the absolute value of the first difference U detla exceeds the first detection threshold U threshold within a continuous 0.5 ms, it is determined that the grid power of the household energy storage system is lost. At this time, the photovoltaic energy storage inverter quickly switches to the off-grid power supply mode to ensure continuous and stable power supply for the electrical equipment at the backup port. Specifically, referring to Figure 5 , Figure 5 is the actual effect diagram of the photovoltaic energy storage inverter switching to off-grid operation when the grid power loss of the household energy storage system is detected.

[0099] The embodiment of the present invention provides a power loss detection method based on a household energy storage system, which has the following technical effects:

[0100] (1) Less data processing volume and improved operation processing speed; originally, it was necessary to directly process the data of the three-phase grid voltage within the entire power frequency cycle. After coordinate transformation and decoupling filtering, the U d value data within 3 ms can be obtained, and then the detection of the grid power loss of the household energy storage system can be accurately completed based on the U d value data within 3 ms. The data volume is greatly reduced, and the operation processing speed is greatly improved.

[0101] (2) Improve the accuracy of detection; in this embodiment, the situation of the simultaneous loss of the three-phase grid or the loss of a single phase can be accurately detected, and at the same time, it has strong anti-interference ability against short-term abnormal fluctuations of the grid and will not cause false detection.

[0102] On the other hand, an embodiment of the present invention further includes a power failure detection system based on a household energy storage system, including:

[0103] An acquisition module, configured to acquire three-phase grid voltage signals;

[0104] A first transformation module, configured to transform the three-phase grid voltage signals from a three-phase stationary coordinate system to a two-phase stationary coordinate system, obtaining a first voltage signal and a second voltage signal;

[0105] A second transformation module, configured to transform the first voltage signal and the second voltage signal from a two-phase stationary coordinate system to a positive-sequence two-phase rotating coordinate system, obtaining a first positive-sequence voltage signal and a second positive-sequence voltage signal;

[0106] A third transformation module, configured to transform the first voltage signal and the second voltage signal from a two-phase stationary coordinate system to a negative-sequence two-phase rotating coordinate system, obtaining a first negative-sequence voltage signal and a second negative-sequence voltage signal;

[0107] A calculation module, configured to perform decoupling and filtering calculations on the first positive-sequence voltage signal, the second positive-sequence voltage signal, the first negative-sequence voltage signal, and the second negative-sequence voltage signal, obtaining a third voltage signal value;

[0108] A first acquisition module, configured to acquire a first value and a second value, where the first value is the current third voltage signal value, and the second value is the third voltage signal value before a first preset time period;

[0109] A second acquisition module, configured to obtain a first difference according to the first value and the second value;

[0110] A selection module, configured to select a first detection threshold according to the third voltage signal value and the first difference;

[0111] A judgment module, configured to judge whether the grid of the household energy storage system has a power failure according to the first difference and the first detection threshold.

[0112] Figure 1 The content in the method embodiment shown is applicable to the system embodiment of the present invention. The functions specifically implemented by the system embodiment of the present invention are Figure 1 the same as those in the method embodiment shown, and the beneficial effects achieved are Figure 1 the same as those achieved by the method embodiment shown.

[0113] Referring to Figure 6 , an embodiment of the present invention further provides a power failure detection device 200 based on a household energy storage system, specifically including:

[0114] At least one processor 210;

[0115] At least one memory 220 for storing at least one program;

[0116] When the at least one program is executed by the at least one processor 210, the at least one processor 210 implements the method as Figure 1 shown.

[0117] Among them, the memory 220, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. The memory 220 may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory 220 optionally includes a remote memory remotely disposed relative to the processor 210, and these remote memories can be connected to the processor 210 through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0118] It can be understood that Figure 6 the device structure shown in

[0119] does not constitute a limitation on the device 200, and may include more or fewer components than shown in the figure, or combine certain components, or different component arrangements. Figure 6 In the device 200 as shown in Figure 1 the figure, the processor 210 can retrieve the program stored in the memory 220 and execute the steps of the embodiments shown in but not limited to

[0120] The device 200 embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the embodiments.

[0121] The embodiment of the present invention also provides a computer-readable storage medium, and the computer-readable storage medium stores a program executable by a processor. The program executable by the processor is used to implement the method as Figure 1 shown.

[0122] The embodiment of the present application also discloses a computer program product or a computer program. The computer program product or the computer program includes computer instructions, and the computer instructions are stored in a computer-readable storage medium. The processor of the computer device can read the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the method as Figure 1 shown.

[0123] It will be understood that all or some of the steps and systems disclosed in the above methods can be implemented as software, firmware, hardware and their appropriate combinations. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor or a microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include a computer storage medium (or non-transitory medium) and a communication medium (or transitory medium). As is well known to those of ordinary skill in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information, such as computer-readable instructions, data structures, program modules or other data. Computer storage media includes but is not limited to RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassettes, tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those of ordinary skill in the art that communication media typically contain computer-readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transmission mechanism, and can include any information delivery medium.

[0124] The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. A power-off detection method based on a household energy storage system, characterized in that, Including: Collecting three-phase grid voltage signals; Transforming the three-phase grid voltage signals from a three-phase stationary coordinate system to a two-phase stationary coordinate system to obtain a first voltage signal and a second voltage signal; Transforming the first voltage signal and the second voltage signal from a two-phase stationary coordinate system to a positive-sequence two-phase rotating coordinate system to obtain a first positive-sequence voltage signal and a second positive-sequence voltage signal; Transforming the first voltage signal and the second voltage signal from a two-phase stationary coordinate system to a negative-sequence two-phase rotating coordinate system to obtain a first negative-sequence voltage signal and a second negative-sequence voltage signal; Performing decoupling and filtering calculations on the first positive-sequence voltage signal, the second positive-sequence voltage signal, the first negative-sequence voltage signal, and the second negative-sequence voltage signal to obtain a third voltage signal value; Obtaining a first value and a second value, where the first value is the current third voltage signal value, and the second value is the third voltage signal value before a first preset time period; Obtaining a first difference according to the first value and the second value; Selecting a first detection threshold according to the third voltage signal value and the first difference; Judging whether the grid of the household energy storage system is powered off according to the first difference and the first detection threshold; the step of selecting the first detection threshold according to the third voltage signal value and the first difference is executed by the following formula: where U threshold represents the first detection threshold, U d represents the third voltage signal value, U detla represents the first difference.

2. The power-off detection method based on a household energy storage system according to claim 1, characterized in that, The step of transforming the three-phase grid voltage signals from a three-phase stationary coordinate system to a two-phase stationary coordinate system to obtain a first voltage signal and a second voltage signal is executed by the following formula: where U a , U b , U c are the three-phase grid voltage signals obtained by acquisition, U af is the first voltage signal, and U bt is the second voltage signal.

3. The power-off detection method based on a household energy storage system according to claim 1, characterized in that, The step of transforming the first voltage signal and the second voltage signal from a two-phase stationary coordinate system to a positive-sequence two-phase rotating coordinate system to obtain a first positive-sequence voltage signal and a second positive-sequence voltage signal is executed by the following formula: Where, U af is the first voltage signal, U bt is the second voltage signal, U dpos is the first positive-sequence voltage signal, U qpos is the second positive-sequence voltage signal, and θ is the angle between the two-phase stationary coordinate system and the positive-sequence two-phase rotating coordinate system.

4. The power-off detection method based on a household energy storage system according to claim 1, characterized in that, The step of transforming the first voltage signal and the second voltage signal from a two-phase stationary coordinate system to a negative-sequence two-phase rotating coordinate system to obtain a first negative-sequence voltage signal and a second negative-sequence voltage signal is executed by the following formula: where U af is the first voltage signal, U bt is the second voltage signal, U dneg is the first negative sequence voltage signal, U qneg is the second negative sequence voltage signal, and θ is the angle between the two-phase stationary coordinate system and the negative sequence two-phase rotating coordinate system.

5. The power-off detection method based on a household energy storage system according to claim 1, characterized in that, The specific method for obtaining the first difference according to the first value and the second value is: Subtracting the second value from the first value to obtain the first difference.

6. The power-off detection method based on a household energy storage system according to claim 1, characterized in that, The step of judging whether the grid of the household energy storage system is powered off according to the first difference and the first detection threshold includes: Comparing the absolute value of the first difference with the first detection threshold; If the absolute value of the first difference exceeds the first detection threshold within a continuous first time period, it is determined that the grid of the household energy storage system is powered off.

7. A power-off detection system based on a household energy storage system, characterized in that, Including: A collection module for collecting three-phase grid voltage signals; A first transformation module for transforming the three-phase grid voltage signals from a three-phase stationary coordinate system to a two-phase stationary coordinate system to obtain a first voltage signal and a second voltage signal; A second transformation module for transforming the first voltage signal and the second voltage signal from a two-phase stationary coordinate system to a positive-sequence two-phase rotating coordinate system to obtain a first positive-sequence voltage signal and a second positive-sequence voltage signal; A third transformation module for transforming the first voltage signal and the second voltage signal from a two-phase stationary coordinate system to a negative-sequence two-phase rotating coordinate system to obtain a first negative-sequence voltage signal and a second negative-sequence voltage signal; A calculation module for performing decoupling and filtering calculations on the first positive-sequence voltage signal, the second positive-sequence voltage signal, the first negative-sequence voltage signal, and the second negative-sequence voltage signal to obtain a third voltage signal value; A first acquisition module for acquiring a first value and a second value, where the first value is the current third voltage signal value, and the second value is the third voltage signal value one first preset time period ago; A second acquisition module for obtaining a first difference according to the first value and the second value; A selection module for selecting a first detection threshold according to the third voltage signal value and the first difference; A judgment module for judging whether the household energy storage system grid has lost power according to the first difference and the first detection threshold; The function of the selection module is specifically executed by the following formula: where U threshold represents the first detection threshold, U d represents the third voltage signal value, and U detla represents the first difference.

8. An off - power detection device based on a household energy storage system, characterized in that, Including: At least one processor; At least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the method according to any one of claims 1-6.

9. A computer - readable storage medium, characterized in that, Stored thereon is a program executable by a processor, and the program executable by the processor is used to implement the method according to any one of claims 1-6 when executed by the processor.

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