Power failure detection method, power conversion device, and energy storage system

Abstract

The present application provides a power failure detection method, comprising: obtaining a first fundamental wave signal of an alternating current at a first moment and a second fundamental wave signal of the alternating current at a second moment, wherein the second moment differs from the first moment by N sampling periods, and N is a positive integer; then on the basis of the first fundamental wave signal and the second fundamental wave signal, obtaining a target signal orthogonal to the first fundamental wave signal; on the basis of the first fundamental wave signal and the target signal, rapidly obtaining a real-time voltage amplitude of the alternating current at the first moment; and on the basis of the real-time voltage amplitude, determining a power failure detection result of the alternating current.

Description

Power failure detection method, power conversion device and energy storage system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on August 3, 2023, with application number 2023109799748 and invention name “Power-off detection method, power conversion device and energy storage system”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of power supply technology, and in particular to a power failure detection method, a power conversion device, and an energy storage system. Background Art

[0004] The statements herein merely provide background information related to the present application and do not necessarily constitute exemplary techniques.

[0005] Whether an uninterruptible power supply (UPS) can quickly detect a mains power outage and quickly switch power sources is one of the important performance indicators for measuring UPS. In related technologies, an AC phase-locked loop (PLL) algorithm is often used to detect the mains voltage amplitude. When the mains voltage amplitude drops to a certain threshold, it is considered that the mains power has been lost. However, due to the presence of an integral link in the loop of the AC phase-locked loop algorithm, the detection speed is relatively slow. When the mains power suddenly loses power, it takes a long time to detect that the mains voltage amplitude has dropped below the threshold, which results in a longer time to switch the power source, that is, the UPS switching time.

[0006] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute relevant technology known to ordinary technicians in this field.

[0007] Summary of the Invention

[0008] The present application provides a power failure detection method, a power conversion device, and an energy storage system.

[0009] One embodiment of the present application provides a power failure detection method, comprising: obtaining a first fundamental wave signal of alternating current (AC) at a first moment and a second fundamental wave signal at a second moment, wherein the second moment differs from the first moment by N sampling periods, and N is a positive integer. Then, based on the first fundamental wave signal and the second fundamental wave signal, a target signal orthogonal to the first fundamental wave signal is obtained. Based on the first fundamental wave signal and the target signal, a real-time voltage amplitude of the AC at the first moment is obtained. Finally, a power failure detection result of the AC is determined based on the real-time voltage amplitude.

[0010] One embodiment of the present application also provides a power conversion device, including a power converter, an AC input interface, a backup power input interface, a load interface and a controller. The AC input interface is configured to connect to an AC power source to receive AC power. The load interface is configured to connect to an electrical load. The backup power input interface is configured to connect to a backup power source to receive power from the backup power source. The power converter is connected to the AC input interface, the load interface and the backup power input interface; the power converter is configured to perform power conversion on the AC power or the backup power source, and then supply power to the electrical load through the load interface. The controller is electrically connected to the AC input interface and the power converter, and the controller is configured to control the power converter, and is also configured to execute the power failure detection method described in the first aspect or any one of the embodiments of the first aspect.

[0011] An embodiment of the present application further provides an energy storage system, comprising a power conversion device and a battery device. The power conversion device is the power conversion device as described in any of the above embodiments.

[0012] An embodiment of the present application also provides an electronic device, including a processor and a memory, wherein the memory is configured to store programs, instructions or codes, and the processor is configured to execute the programs, instructions or codes in the memory to complete the power-off detection method described in the first aspect or any embodiment of the first aspect.

[0013] One embodiment of the present application further provides a power failure detection device, comprising: an acquisition module, a first processing module, a second processing module, and a power failure detection module. The acquisition module is configured to acquire a first fundamental wave signal of the alternating current at a first moment and a second fundamental wave signal at a second moment, wherein the second moment differs from the first moment by N sampling periods, and N is a positive integer. The first processing module is configured to obtain a target signal orthogonal to the first fundamental wave signal based on the first fundamental wave signal and the second fundamental wave signal. The second processing module is configured to obtain a real-time voltage amplitude of the alternating current at the first moment based on the first fundamental wave signal and the target signal. The power failure detection module is configured to determine a power failure detection result of the alternating current based on the real-time voltage amplitude.

[0014] An embodiment of the present application further provides a computer-readable storage medium storing a computer program, which is loaded by a processor to execute the power-off detection method described in the first aspect or any embodiment of the first aspect.

[0015] The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments or exemplary technologies of the present application, the following briefly introduces the drawings required for use in the description of the embodiments or exemplary technologies. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, without paying any creative work, they can also obtain drawings of other embodiments based on these drawings.

[0017] FIG1 is a schematic diagram of a phase-locked loop in the related art.

[0018] FIG2 is a diagram showing an application scenario of a power-off detection method provided in one embodiment of the present application.

[0019] FIG3 is a flow chart of a power failure detection method provided in one embodiment of the present application.

[0020] FIG4 is a waveform diagram of the real-time voltage amplitude detected by the phase-locked loop in the power-off detection method shown in FIG3 and related technologies.

[0021] FIG5 is a detailed flowchart of step S40 in FIG3 .

[0022] FIG6 is another detailed flowchart of step S40 in FIG3 .

[0023] FIG7 is a schematic diagram of a power conversion device provided in one embodiment of the present application.

[0024] FIG8A is a schematic diagram of an energy storage system provided in one embodiment of the present application.

[0025] FIG8B is another schematic diagram of an energy storage system provided in one embodiment of the present application.

[0026] FIG9 is a schematic diagram of an electronic device provided in one embodiment of the present application.

[0027] FIG10 is a schematic diagram of a power failure detection device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0028] It should be noted that the terms "first" and "second" in the description, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0029] It should also be noted that the method disclosed in the embodiments of the present application or the method shown in the flowchart includes one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchanged with each other, and some steps can also be deleted.

[0030] The following will describe some embodiments with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0031] Whether an uninterruptible power supply (UPS) can quickly detect a power outage and quickly switch power supply when the mains power is lost is one of the important performance indicators for measuring UPS. In related technologies, an AC phase-locked loop algorithm is often used to detect the mains voltage amplitude. The mains voltage amplitude is the effective value of the mains voltage. It takes at least one power frequency cycle (that is, the mains cycle) to obtain the mains voltage amplitude, which takes a relatively long time. Specifically, as shown in Figure 1, the AC phase-locked loop algorithm will transform the three-phase electrical quantity in the stationary coordinate system abc into the two-phase electrical quantity V in the stationary coordinate system αβ. α 、V β (corresponding to Clark transformation), and then the two-phase electric quantity V in the stationary coordinate system αβ α 、V β Transformed into DC quantity V under rotating coordinate system dq d 、V q (corresponding to park transformation). d represents the mains voltage amplitude. Therefore, when V d When V drops to a certain threshold, it is considered that the mains power is off. d When the voltage exceeds a certain threshold, it means that the AC voltage amplitude can no longer meet the current conditions, and it can also be considered that the AC power is off.

[0032] However, the AC phase-locked loop algorithm contains an integral component. For example, in Figure 1, the phase-locked loop incorporates a proportional-integral (PI) controller and an integral (I) controller. This integral component requires a certain integration time, resulting in a long latency and slow detection speed. When the AC phase-locked loop algorithm experiences a sudden loss of mains power due to abnormal grid operation or a line fault, it takes a long time (typically at least one power frequency cycle) to detect when the mains voltage amplitude has dropped below the threshold. This results in a longer switching time for the power source, and consequently, a longer UPS switching time.

[0033] Therefore, the present application provides a power failure detection method, a power conversion device and an energy storage system, which do not involve complex phase-locked loop calculations and can quickly detect the real-time voltage amplitude of the AC power, thereby being able to promptly and quickly detect AC power failures, so as to facilitate timely and rapid switching of the power supply.

[0034] The technical solution of the present application is further described in detail below with reference to the accompanying drawings.

[0035] Please refer to Figure 2, which is a schematic diagram of an application scenario of the power failure detection method provided in an embodiment of the present application. In the scenario shown in Figure 2, the controller 10 is connected to the power converter 20, which is further connected to the AC power source 200, the power load 300, and the battery device 400. The AC power source 200 can be, for example, a mains power grid or other microgrid, and the power load 300 can include an AC load.

[0036] When the AC power supply 200 is supplying power normally, the AC power supply 200 can be used to directly supply power to the electrical load 300 through a bypass. The power converter 20 can be inoperative. When the input power of the AC power supply 200 is greater than the power demand of the electrical load 300 and the battery device 400 needs to be charged, the controller 10 can control the power converter 20 to operate so as to convert the power supply of the AC power supply 200 and supply power to the battery device 400. Once it is detected that the AC power supply 200 is powered off, the controller 10 needs to control the power converter 20 to switch the mode so that the power converter 20 converts the power supply of the battery device 400 and supplies power to the electrical load 300. In order to ensure the normal power supply of the electrical load 200, it is necessary to quickly detect the AC power failure to switch the mode of the power converter 20.

[0037] It can be understood that the power failure detection method in this embodiment can be applied to the above application scenarios, and can also be applied to other application scenarios that require AC power failure detection.

[0038] Next, the power failure detection method provided in the embodiment of the present application is introduced.

[0039] Please refer to Figure 3, which shows a power failure detection method provided by an embodiment of the present application. This method can be executed by the controller 10 in Figure 2, or can be implemented by a dedicated power failure detection controller.

[0040] As shown in FIG3 , the power-off detection method includes the following steps:

[0041] S10: Acquire a first fundamental wave signal of the alternating current at a first moment and a second fundamental wave signal at a second moment.

[0042] It is understood that alternating current (AC) consists of a fundamental signal and harmonic signals. The fundamental signal is the primary component of AC, while the harmonic signals represent interference. The frequency of the harmonic signals is typically an integer multiple of the fundamental signal's frequency. Therefore, the controller 10 can periodically acquire the AC electrical signal, extract the fundamental signal from the AC electrical signal, and use the real-time voltage amplitude of the fundamental signal as the real-time voltage amplitude of the AC. After each acquisition of the fundamental signal, the controller 10 can also record and store the acquired fundamental signal for subsequent use.

[0043] In step S10, the first moment is the current moment, and the second moment differs from the first moment by N sampling periods T s .

[0044] Specifically, the second moment is N sampling periods T earlier than the first moment. s .

[0045] Wherein, N is a positive integer, for example, it can be 3, 5, 7, 8, etc., which is not limited here. Sampling period T s It can be understood as the time interval for sampling the fundamental signal, the sampling period T s The size of can be set according to the actual parameters of the power converter 20 and the controller 10, and is not limited here. In the embodiment of the present application, the sampling period T s In one embodiment, the sampling period T s It can reach milliseconds or even microseconds, for example, it can be set to 41 microseconds. Taking the AC frequency of 50Hz as an example, its corresponding period is 20 milliseconds, which is obviously longer than the sampling period T of 41 microseconds. s .

[0046] In the embodiment of the present application, the alternating current is a sinusoidal signal, so the first fundamental wave signal and the second fundamental wave signal are both sinusoidal signals. The first fundamental wave signal can be expressed as The second fundamental signal can be expressed as Where V m is the required real-time voltage amplitude, is the phase of the first fundamental signal, is the phase of the second fundamental wave signal. The phase difference between the second fundamental wave signal and the first fundamental wave signal Wherein ω is the angular frequency of the fundamental signal, ω=2πf, and f is the frequency of the fundamental signal.

[0047] S20: Obtain a target signal orthogonal to the first fundamental wave signal according to the first fundamental wave signal and the second fundamental wave signal.

[0048] It can be understood that the target signal can be expressed as in The target signal is orthogonal to the first fundamental signal, which means the phase difference between the target signal and the first fundamental signal is

[0049] Since the formula for the sum and difference of two angles of a sine function has been proven, a sine function can be decomposed into other sine functions. Therefore, in step S20, the second fundamental signal can be deconstructed into an expression related to the first fundamental signal and the target signal. Therefore, if the second fundamental signal and the first fundamental signal are known, the target signal can be obtained based on the expression of the first fundamental signal and the second fundamental signal.

[0050] S30: Obtaining the real-time voltage amplitude V of the AC power at the first moment according to the first fundamental wave signal and the target signal m .

[0051] Since there is a square relationship between the orthogonal first fundamental wave signal and the target signal, that is: This square relationship can eliminate the phase, so that the result is only related to the real-time voltage amplitude V m Therefore, in step S30, the real-time voltage amplitude V at the first moment can be obtained based on the first fundamental signal and the target signal and the square relationship between the two. m .

[0052] It can be understood that the controller 10 obtains the real-time voltage amplitude V at the first moment each time. m After that, the real-time voltage amplitude V m Record and store for later use.

[0053] S40: Determine the AC power failure detection result according to the real-time voltage amplitude.

[0054] When the AC power is lost, its real-time voltage amplitude eventually drops to zero. Conversely, when the AC power is not lost, its real-time voltage amplitude remains stable within a certain range. Therefore, in step S40, if the real-time voltage amplitude changes significantly and exceeds the corresponding voltage threshold, it can be determined that the AC power has been lost. If the real-time voltage amplitude remains stable within a certain range and does not exceed the corresponding voltage threshold, it can be determined that the AC power has not been lost.

[0055] The power outage detection method provided in the embodiments of the present application obtains a first fundamental wave signal of the AC power at a first moment and a second fundamental wave signal at a second moment. These two fundamental wave signals are then used to derive a target signal orthogonal to the first fundamental wave signal. Furthermore, based on the mutually orthogonal first fundamental wave signal and target signal, the real-time voltage amplitude of the AC power at the first moment can be directly obtained. In this embodiment, AC power outage detection can be achieved within only N sampling cycles, while traditional phase-locked loop (PLL) calculation methods require at least one AC power cycle to achieve power outage detection. To ensure detection accuracy, in this embodiment, hundreds of sampling points are used within one AC power cycle, meaning hundreds of sampling cycles are provided within one AC power cycle. Therefore, the duration of N sampling cycles is significantly shorter than that of one AC power cycle, facilitating timely and rapid detection of AC power outages, enabling rapid switching to the available power source and shortening UPS switching time. Furthermore, the power outage detection method provided in the embodiments of the present application reduces computational complexity and cost, and is not affected by the accuracy of AC power phase detection.

[0056] For better understanding, the method provided in the embodiments of the present application is further illustrated with two examples below.

[0057] In one embodiment, the first fundamental signal It can be further expressed as V m sin(ωt), where t is time. Correspondingly, the second fundamental signal It can be further expressed as V m sin(ωt+NωT s ). Target signal It can be further expressed as V m sin(ωt+π / 2).

[0058] Furthermore, in step S20, according to the two-angle sum and difference formula in the sine function, the second fundamental wave signal V m sin(ωt+NωT s ) can be converted into expression (1): V m sin(ωt+NωT s )=V m [sin(ωt)cos(NωT s )+cos(ωt)+sin(NωT s )] (1)

[0059] Among them, V m cos(NωT s ) is the sinusoidal signal V m sin(NωT s ) quadrature cosine signals.

[0060] Since the orthogonal sine and cosine signals can be converted, V m cos(ωt) can be expressed as the target signal V m sin(ωt+π / 2). Therefore, expression (1) can be transformed into expression (2): V m sin(ωt+NωT s )=V m [sin(ωt)cos(NωT s )+sin(ωt+π / 2)sin(NωT s )] (2)

[0061] Then, according to expression (2), the target signal can be obtained:

[0062] It can be understood that the first fundamental signal V m sin(ωt), the second fundamental wave signal V m sin(ωt+NωT s ) can be obtained by sampling. Therefore, in NωT s When determined, the corresponding sin(NωT s )、cos(NωT s ) can be calculated. Therefore, according to expression (3), the target signal V m sin(ωt+π / 2).

[0063] Since there is a square relationship between the first fundamental signal and the target signal: Therefore, step S30 may include:

[0064] The first step is to calculate the sum of the square of the first fundamental signal and the square of the target signal.

[0065] The second step is to use the square root of the sum as the real-time voltage amplitude of the AC power. The calculation result is the real-time voltage amplitude V at the first moment. m .

[0066] That is to say, according to expression (4), the real-time voltage amplitude V at the first moment is obtained: m :

[0067] Similarly, in another embodiment, the first fundamental wave signal Correspondingly, the second fundamental signal Target signal

[0068] Referring to the calculation process of the above embodiment, in step S20, the target signal can be obtained according to expression (5):

[0069] Since there is a square relationship between the first fundamental signal and the target signal: Therefore, in step S30, according to the first fundamental signal and the target signal, the real-time voltage amplitude V at the first moment is obtained by expression (6): m :

[0070] It can be seen that the process of steps S20 to S30 can be understood as combining expressions (3) and (4), or combining expressions (5) and (6) to obtain the real-time voltage amplitude V at the first moment: m .

[0071] It can be understood that when the AC power supply 200 is supplying power normally, the waveform of the AC power it outputs is a sine wave. The instantaneous value of the sine wave changes periodically over time, and the amplitude of the sine wave remains constant. Therefore, when the AC power supply 200 is supplying power normally, the real-time voltage amplitude V obtained by the method provided in the embodiment of the present application is m Relatively stable.

[0072] For example, referring to FIG4 , taking the AC power source 200 as a low-voltage grid as an example, before time t1, the instantaneous value of the AC voltage changes periodically within the voltage range of [-170V, +170V], and the real-time voltage amplitude V m Maintained at 170V. Therefore, the real-time voltage amplitude V m The waveform appears as a smooth horizontal line. At time t1, AC power supply 200 suddenly loses power, causing the instantaneous value of its output AC voltage to rapidly change from -170V to 0. In other words, the first fundamental wave signal at time t1 suddenly drops to 0. The AC waveform is no longer a sine wave, but instead abruptly transitions to the baseline of 0V.

[0073] Because the AC power source 200 has not been powered off before time t1, the second fundamental wave signal obtained before time t1 still has a certain instantaneous voltage value, the polarity of which may be positive or negative. For example, in FIG4 , the instantaneous voltage value is negative, approximately -170V.

[0074] Since V m sin(ωt) is 0, V m sin(ωt+NωT s ) is not 0, V m sin(NωT s ) is not 0, so referring to expression (3) or (5), Vm sin(ωt-π / 2) will not be 0, and its value will change due to V m sin(ωt) suddenly becomes 0, V m sin(ωt+NωT s ), V m sin(NωT s ) has a corresponding voltage instantaneous value and increases. For example, in Figure 4, V m The instantaneous value of the voltage sin(ωt) is approximately -170V. Therefore, the real-time voltage amplitude V at time t1 calculated by expressions (3), (4), or (5), (6) is m It is about 1700V.

[0075] It can be seen that in the embodiment of the present application, the real-time voltage amplitude V associated with the first fundamental wave signal and the second fundamental wave signal m It will not drop to 0 immediately, but will increase suddenly at time t1. As can be seen in Figure 4, the real-time voltage amplitude V m Increased from 170V to 1700V.

[0076] Since the AC power is always in the 0 voltage state after time t1, the AC power waveform coincides with the baseline of 0V. s After that, the first fundamental wave signal is still 0, and the second fundamental wave signal and the third fundamental wave signal are also updated to 0. Therefore, the real-time voltage amplitude V m After reaching 1700V, it will quickly drop below 170V and finally drop to 0 at time t2.

[0077] As can be seen from FIG4 , when AC power failure occurs, the power failure detection method in this embodiment is based on N sampling periods T s The real-time voltage amplitude V can be detected by the data in m Changes from 170V to 0V. And the real-time voltage amplitude V m The time from 170V to 0V, that is, the time D1 from time t1 to time t2, is very short. The AC phase-locked loop algorithm in the related art detects the voltage amplitude V d The time D2 for decreasing from 170V to 20V is much longer than D1.

[0078] Furthermore, the sampling period T in the embodiment of the present application is s It can reach microsecond level, while the period of AC power tracked by the phase-locked loop is generally in millisecond level, which is much longer than N sampling periods T sOn the other hand, there is a time delay in the integration link of the AC phase-locked loop algorithm (for example, it can reach 3 to 4 ms). Therefore, compared with the phase-locked loop, the embodiment of the present application can obtain the fundamental wave signal of the AC power more quickly, and then the detected real-time voltage amplitude V m Changes can be shown more quickly and instantly.

[0079] Therefore, the method provided in the embodiment of the present application can detect the real-time voltage amplitude V more quickly and timely. m Moreover, when the AC power is lost, the real-time voltage amplitude V detected by the method provided in the embodiment of the present application is m The amplitude of the change is also more drastic and obvious, and there may be a situation where it first rises and then falls. Therefore, the method provided by the embodiment of the present application is easier to detect AC power failure, and is also more conducive to improving the accuracy of power failure detection.

[0080] Therefore, as shown in FIG5 , in step S40, the process of determining the AC power failure detection result according to the real-time voltage amplitude may include the following steps:

[0081] S401a: Confirm the real-time voltage amplitude V m Is it greater than the first voltage threshold, or confirm the real-time voltage amplitude V m Is it less than the second voltage threshold?

[0082] Among them, the first voltage threshold corresponds to the real-time voltage amplitude V in FIG4 m The second voltage threshold corresponds to the real-time voltage amplitude V in FIG4. m Therefore, the first voltage threshold is greater than the second voltage threshold.

[0083] It is understood that the specific values ​​of the first voltage threshold and the second voltage threshold can be set accordingly according to actual conditions and are not limited here. For example, the first voltage threshold can be set to any value or a range of values ​​in (170V, 1700V), such as 230V. The second voltage threshold can be set to any value or a range of values ​​in [0, 170V), such as 90V.

[0084] S402a: In real-time voltage amplitude V m Greater than the first voltage threshold, or the real-time voltage amplitude V m When the voltage is less than the second voltage threshold, it is determined that the AC power is off.

[0085] S403a: In real-time voltage amplitude V m Not greater than the first voltage threshold, or the real-time voltage amplitude V m When the voltage is not less than the second voltage threshold, it is determined that the AC power is not cut off.

[0086] It can be seen that in the embodiment of the present application, as long as the real-time voltage amplitude V m If any one of the conditions of being greater than the first voltage threshold or less than the second voltage threshold is met, it can be determined that the AC power is off.

[0087] Of course, in some embodiments, the real-time voltage amplitude obtained by the current calculation may be compared with the real-time voltage amplitude obtained previously to confirm whether the AC power is off.

[0088] Specifically, as shown in FIG6 , the process of determining the AC power failure detection result according to the real-time voltage amplitude may include the following steps:

[0089] S401b: Determine whether the absolute value of the difference between the real-time voltage amplitude at the first moment and the real-time voltage amplitude calculated last time is greater than a preset voltage threshold.

[0090] The preset voltage threshold can be set according to actual conditions and is not limited here. For example, the preset voltage threshold can be set to 60V, 80V, etc.

[0091] S402b: When the absolute value of the difference between the real-time voltage amplitude at the first moment and the real-time voltage amplitude calculated last time is greater than a preset voltage threshold, determine that the AC power is off.

[0092] S403b: When the absolute value of the difference between the real-time voltage amplitude at the first moment and the real-time voltage amplitude calculated last time is not greater than the preset voltage threshold, determine that the AC power is not cut off.

[0093] It can be seen that in the embodiment of the present application, as long as the current real-time voltage amplitude V m If the change in the real-time voltage amplitude compared to the last calculated value is greater than a preset voltage threshold, it can be determined that the AC power is off.

[0094] In an embodiment of the present application, the power failure detection method may further include:

[0095] The fundamental wave of the alternating current is extracted through a filter to obtain the fundamental wave signal at the corresponding moment.

[0096] Therefore, the first fundamental wave signal in step S10 and the second fundamental signal All can be obtained through the filter. s It can reach the microsecond level, so the filter can quickly obtain the fundamental signal at the corresponding moment.

[0097] In some embodiments, the filter may use a generalized second-order integrator (SOGI). It is understood that the generalized second-order integrator can extract only the fundamental signal in the AC power, and the extracted fundamental signal has no phase delay. Therefore, it can be ensured that the target signal obtained in the subsequent step S20 and the first fundamental signal have good sinusoidal and orthogonal properties, so as to accurately obtain the real-time voltage amplitude V at the first moment. m .

[0098] Of course, in other embodiments, the filter may be a bandpass filter or other circuit / module / unit / device capable of extracting the fundamental signal. It will be appreciated that a bandpass filter allows only the frequency band of the fundamental signal to pass through while effectively suppressing signals of other frequencies (such as harmonics). Therefore, the bandpass filter can accurately extract the fundamental signal and filter out other signals besides the fundamental signal.

[0099] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should know that this application is not limited to the described order of actions, because according to this application, certain steps can be performed in other orders or simultaneously.

[0100] Please refer to FIG. 7 , which shows a schematic diagram of a power conversion device 100 provided in an embodiment of the present application.

[0101] As shown in FIG. 7 , the power conversion device 100 may include an AC power input interface 30 , a backup power input interface 50 , a load interface 40 , a power converter 20 , and a controller 10 .

[0102] The AC power input interface 30 is configured to be electrically connected to an AC power source 200. The AC power source 200 can be a power source that can provide AC power, such as a power grid.

[0103] The backup power input interface 50 is configured to be electrically connected to a backup power supply 500. The backup power supply 500 can be a power supply such as a generator or a battery pack.

[0104] The load interface 40 is configured to electrically connect to an electrical load 300. The electrical load 300 may include an AC load. In some embodiments, the electrical load 300 may also include a DC load.

[0105] The power converter 20 may adopt any circuit capable of realizing a power conversion function. Its specific circuit structure may be configured accordingly based on the connected AC power source 200, the backup power source 500, and the power load 300, and is not limited here. For example, in one embodiment, the power converter 20 may include an AC / AC (alternating current / alternating current) converter, a bidirectional DC / AC (direct current / alternating current) converter, or a bidirectional DC / DC (direct current / direct current) converter.

[0106] The power converter 20 is electrically connected to the AC power input interface 30, the backup power input interface 50, and the load interface 40. Thus, the AC power source 200, the AC power input interface 30, the power converter 20, and the load interface 40 form one power supply path, while the battery device 400, the backup power input interface 50, the power converter 20, and the load interface 40 form another power supply path.

[0107] The controller 10 may include a microcontroller unit (MCU), or other circuits, units, modules or devices with control functions, which are not limited here.

[0108] The controller 10 is also electrically connected to the AC power input interface 30. Therefore, when the AC power input interface 30 is connected to the AC power source 200, the AC power is supplied to the AC power input interface 30. Furthermore, the controller 10 can extract the fundamental wave signal from the AC power from the AC power input interface 30 using an internal filter and perform the power loss detection method illustrated in Figures 3 to 6 to detect whether the AC power source 200 has lost power. Of course, in some embodiments, the filter can also be provided independently and connected between the controller 10 and the AC power input interface 30.

[0109] The controller 10 is also electrically connected to the power converter 20 . Therefore, the controller 10 can control the power converter 20 .

[0110] Specifically, when the AC power input interface 30 is connected to the AC power source 200 and the load interface 40 is connected to the electrical load 300, the controller 10 can control the power converter 20 to switch to the corresponding power supply mode according to the power failure of the AC power source 200. Different power supply modes can use different power supply channels. For example, if the controller 10 confirms that the AC power source 200 is not powered off, the controller 10 can control the power converter 20 to draw power from the AC power source 200 through the AC power input interface 30, that is, control the power converter 20 to receive the AC power provided by the AC power source 200 through the AC power input interface 30, and after power conversion of the AC power, supply power to the electrical load 300 through the load interface 40, so that the electrical load 300 can be powered on and work.

[0111] Furthermore, when the AC power input interface 30 is connected to the AC power supply 200, the load interface 40 is connected to the electrical load 300, and the backup power input interface 50 is also connected to the backup power supply 500, if the controller 10 confirms that the AC power supply 200 is not powered off, then, when the AC power supply 200 has sufficient power (that is, the input power of the AC power supply 200 is greater than the required power of the electrical load 300) and the battery device 400 needs to be charged, the controller 10 can also control the power converter 20 to charge the battery device 400 through the backup power input interface 50 at the same time.

[0112] When the AC power supply 200 is insufficient in power (i.e., the input power of the AC power supply 200 is less than the power required by the electrical load 300), the controller 10 can also control the power converter 20 to obtain the power of the battery device 400 through the backup power input interface 50 and convert it, and then output it to the electrical load 300 through the load interface 40, so as to avoid the normal operation of the electrical load 300 being affected by insufficient power supply.

[0113] When the AC power input interface 30 is connected to the AC power source 200, the load interface 40 is connected to the power load 300, and the backup power input interface 50 is also connected to the backup power source 500, if the controller 10 determines that the AC power source 200 is powered off, the controller 10 can also control the power converter 20 to stop drawing power from the AC power source 200 through the AC power input interface 30 and switch to drawing power from the backup power source 500 through the backup power input interface 50. That is, the controller 10 controls the power converter 20 to only receive power from the backup power source 500, and after power conversion, supplies power to the power load 300 through the load interface 40. In this way, power outage of the power load 300 can be avoided.

[0114] Please refer to FIG8A , which shows a schematic diagram of an energy storage system 1000 provided in an embodiment of the present application.

[0115] As shown in Figure 8A, energy storage system 1000 may include a power conversion device 100 and a battery device 400. It is understood that the power conversion device 100 and the battery device 400 may be at least partially integrated into one, or the power conversion device 100 and the battery device 400 may be independently provided, which is not limited here.

[0116] In the embodiment of the present application, the energy storage system 1000 is an uninterruptible power supply (UPS), which can provide uninterrupted and stable power to the electrical load 300 through the power conversion device 100 and the battery device 400.

[0117] The power conversion device 100 can refer to the description in the embodiment shown in FIG7 , which will not be repeated here.

[0118] The battery device 400 serves as a backup power source and can be connected to the backup power input interface 50 of the power conversion device 100. Therefore, the power converter 20 in the power conversion device 100 can receive power from the battery device 400 through the backup power input interface 50, and then, after power conversion, the electric energy of the battery device 400 can be supplied to the power load 300 through the load interface 40.

[0119] It is understood that the battery device 400 may include a battery management system (BMS, not shown) and at least one battery cell (not shown). The BMS may be connected to the controller 10 of the power conversion device 100, and the controller 10 may further control whether the battery cell is discharged to the power conversion device 100 or whether the battery cell is charged by the power conversion device 100 through the BMS.

[0120] It is understood that the structure shown in FIG8A does not constitute a specific limitation on the energy storage system 1000. In other embodiments, the energy storage system 1000 may include more or fewer components than shown, or combine or separate certain components, or arrange the components differently.

[0121] For example, in some embodiments, as shown in FIG8B , when the electrical load 300 is an AC load, the energy storage system 1000 may further include a bypass switch 600. The bypass switch 600 may be an electrically controlled switch, such as a mechanical switch such as a relay or contactor, or a semiconductor switch such as a transistor or MOSFET. It is understood that the bypass switch 600 may be integrated with at least a portion of the power conversion device 100 and the battery device 400, or may be independently provided, without limitation herein.

[0122] One end of the bypass switch 600 is connected to the AC input interface 30 of the power conversion device 100, and the other end of the bypass switch 600 is connected to the load interface 40 of the power conversion device 100. Therefore, the AC power source 200, the AC input interface 30, the bypass switch 600, and the load interface 40 can form a new power supply channel.

[0123] The bypass switch 600 may also be connected to the controller 10 in the power conversion device 100 and controlled by the controller 10 .

[0124] Based on this design, when the AC power input interface 30 is connected to the AC power source 200, the load interface 40 is connected to the power load 300, and the backup power input interface 50 is connected to the backup power source 500, and the controller 10 confirms that the AC power source 200 is not powered off, the controller 10 can control the bypass switch 600 to be turned on, so that the AC power from the AC power source 200 can be directly transmitted to the power load 300 through the bypass switch 600. At this time, the power conversion device 100 does not need to operate. If the power demand of the power load 300 is large, the controller 10 can control the power conversion device 100 to operate normally while controlling the bypass switch 600 to be turned on to meet the power demand of the power load 300.

[0125] Of course, when the controller 10 confirms that the AC power supply 200 is powered off, the controller 10 can control the bypass switch 600 to turn off and control the power conversion device 100 to work normally, so that the power converter 20 transmits the power of the battery device 400 to the power load 300, ensuring that the power load 300 is not cut off.

[0126] Please refer to FIG9 , which shows a schematic structural diagram of an electronic device 60 provided in an embodiment of the present application.

[0127] As shown in FIG. 9 , the electronic device 60 may include a processor 601 and a memory 602 .

[0128] The processor 601 may be a central processing unit (CPU), or other general-purpose processors, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0129] The memory 602 may be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or other type of dynamic storage device that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compact disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be configured to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 602 may exist independently and be connected to the processor 601 via a bus. The memory 602 may also be integrated with the processor 601.

[0130] The memory 602 is configured to store programs, instructions, or codes for executing the above power failure detection method, and the execution is controlled by the processor 601. The processor 601 is configured to execute the programs, instructions, or codes stored in the memory 602. The programs, instructions, or codes stored in the memory 602 can execute some or all of the steps of the power failure detection method in the embodiments shown in Figures 3, 5, and 6.

[0131] Please refer to Figure 10, which shows a schematic diagram of a power failure detection device 70 provided in an embodiment of the present application. The power failure detection device 70 can be configured to implement the above-mentioned power failure detection method.

[0132] As shown in Figure 10, the power failure detection device 70 includes an acquisition module 701, a first processing module 702, a second processing module 703, and a power failure detection module 704. The acquisition module 701, the first processing module 702, the second processing module 703, and the power failure detection module 704 are connected in sequence.

[0133] Specifically, the acquisition module 701 may be configured to acquire a first fundamental wave signal of the alternating current at a first moment and a second fundamental wave signal at a second moment, wherein the second moment differs from the first moment by N sampling periods, where N is a positive integer.

[0134] The first processing module 702 may be configured to obtain a target signal orthogonal to the first fundamental wave signal according to the first fundamental wave signal and the second fundamental wave signal.

[0135] The second processing module 703 may be configured to obtain a real-time voltage amplitude of the alternating current at a first moment according to the first fundamental wave signal and the target signal.

[0136] The power failure detection module 704 may be configured to determine a power failure detection result of the AC power according to the real-time voltage amplitude.

[0137] It is understandable that the division of the various modules in the above-mentioned power failure detection device 70 is only configured as an example. In other embodiments, the power failure detection device 70 can be divided into different modules as needed to complete all or part of the functions of the above-mentioned power failure detection device 70.

[0138] The specific implementation of each module in the embodiment of the present application can also correspond to the corresponding description of the method embodiment shown in Figures 3, 5 to 6, so it will not be described in detail here.

[0139] The functional modules in the embodiments of the present application may all be integrated into one processing module / unit, or each module may be a separate module, or two or more modules may be integrated into one module; the above-mentioned integrated modules may be implemented in the form of hardware or in the form of hardware plus software functional modules.

[0140] If the above-mentioned integrated module of the present application is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROM, RAM, magnetic disks or optical disks.

[0141] The present application also provides a computer-readable storage medium for storing a computer program or code. When the computer program or code is loaded and executed by a processor, the steps in the above-mentioned power failure detection method embodiment can be implemented, such as Figures 3, 5, and 6. Among them, the computer-readable 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). The specific implementation of the computer-readable storage medium can be found in the description of memory 602 in Figure 9, which is not repeated here.

[0142] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A power failure detection method, comprising: Acquire a first fundamental wave signal of the alternating current at a first moment and a second fundamental wave signal at a second moment; The second moment differs from the first moment by N sampling periods; N is a positive integer; Obtaining a target signal orthogonal to the first fundamental wave signal according to the first fundamental wave signal and the second fundamental wave signal; Obtaining a real-time voltage amplitude of the alternating current at a first moment according to the first fundamental wave signal and the target signal; A power failure detection result of the alternating current is determined according to the real-time voltage amplitude.

2. The power failure detection method according to claim 1, wherein: The step of determining the AC power failure detection result according to the real-time voltage amplitude includes: When the real-time voltage amplitude is greater than a first voltage threshold, determining that the AC power is off; or, When the real-time voltage amplitude is less than a second voltage threshold, determining that the AC power is off; Wherein, the first voltage threshold is greater than the second voltage threshold.

3. The power failure detection method according to claim 1, wherein: The step of determining the AC power failure detection result according to the real-time voltage amplitude includes: When the absolute value of the difference between the real-time voltage amplitude at the first moment and the real-time voltage amplitude calculated last time is greater than a preset voltage threshold, it is determined that the AC power is off.

4. The power failure detection method according to claim 1, wherein: The step of obtaining a target signal orthogonal to the first fundamental wave signal according to the first fundamental wave signal and the second fundamental wave signal comprises obtaining the target signal by calculation according to the following expression: Among them, V m is the real-time voltage amplitude, ω is the angular frequency, t is the time, T s is the sampling period; V m sin(ωt+π / 2) is the target signal; V m sin(ωt) is the first fundamental wave signal; V m sin(ωt+NωT s ) is the second fundamental wave signal.

5. The power failure detection method according to claim 1, wherein: The step of obtaining the real-time voltage amplitude of the alternating current at a first moment according to the first fundamental wave signal and the target signal includes: Calculating the sum of the square of the first fundamental wave signal and the square of the target signal; The square root of the sum is taken as the real-time voltage amplitude of the alternating current.

6. The power failure detection method according to claim 1, wherein: The method further comprises: The fundamental wave of the alternating current is extracted by a filter to obtain a fundamental wave signal at a corresponding moment.

7. The power failure detection method according to claim 6, wherein: The filter is a generalized second-order integrator.

8. A power conversion device, comprising a power converter, an AC input interface, a backup power input interface, a load interface and a controller; The AC power input interface is configured to connect to an AC power source to receive AC power; The load interface is configured to connect an electrical load; The backup power input interface is configured to connect to a backup power source to receive power from the backup power source; The power converter is connected to the AC power input interface, the load interface and the backup power input interface; the power converter is configured to supply power to the power load through the load interface after power conversion of the AC power or the backup power supply; The controller is electrically connected to the AC power input interface and the power converter. The controller is configured to control the power converter and is further configured to execute the power failure detection method according to any one of claims 1 to 7.

9. The power conversion device according to claim 8, wherein: The controller is configured to: When the AC power supply is not powered off, controlling the power converter to draw power from the AC power supply; When the AC power source fails, the power converter is controlled to obtain power from the backup power source.

10. An energy storage system, comprising a power conversion device and a battery device; the power conversion device is the power conversion device as claimed in claim 8 or 9.

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