Power supply switching method and device for fixed-frequency load and medium

Abstract

The embodiment of the invention discloses a power supply switching method for a fixed-frequency load, a power supply switching device and a medium, and is used for the technical field of load power supply. The power supply mode of the inverter to the fixed-frequency load is that a direct-current source performs inversion power supply after inversion output of the inverter, or an alternating-current source performs bypass power supply, and the method comprises the following steps: in the process of performing bypass power supply to the fixed-frequency load, detecting a bypass frequency corresponding to the output end of the inverter; determining a bypass frequency change rate based on the bypass frequency; determining whether bypass power supply is abnormal or not based on the bypass frequency change rate; and if the bypass power supply is abnormal, switching the bypass power supply to the inverter power supply for the fixed-frequency load. Whether bypass power supply is abnormal or not can be quickly determined based on the bypass frequency change rate without detecting bypass voltage of the output end of the inverter, so that when bypass power supply is abnormal, a fixed-frequency load can be quickly switched from bypass power supply to inverter power supply, and power supply switching time is effectively shortened.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of load power supply technology, and in particular to a power supply switching method, a power supply switching device and a medium for a fixed-frequency load. Background Art

[0002] In the existing inverter, the output end is connected to a load, and the power supply mode of the load includes: inverter power supply and bypass power supply, that is, the load is powered by a DC source after being inverted by the inverter output, or is powered by an AC source connected to the inverter output end. In general, the load is powered by bypass. At this time, it can be determined whether the bypass power supply is abnormal by detecting the bypass voltage at the inverter output end. When the bypass power supply is abnormal, the load is switched from bypass power supply to inverter power supply.

[0003] However, when the load is a fixed-frequency load, when the bypass power supply is abnormal (such as AC power failure), the fixed-frequency load will generate an induced electromotive force, and the bypass virtual voltage can still be detected at the output end of the inverter. It will be difficult to quickly determine whether there is an abnormality in the bypass power supply by detecting the bypass voltage at the output end of the inverter. It is difficult to quickly switch the fixed-frequency load from bypass power supply to inverter power supply, resulting in a long switching time. Summary of the invention

[0004] The embodiments of the present application provide a power supply switching method, a power supply switching device and a medium for a fixed-frequency load, which can quickly switch the fixed-frequency load from bypass power supply to inverter power supply when an abnormality occurs in the bypass power supply, thereby effectively shortening the power supply switching time.

[0005] The embodiment of the present application provides a power supply switching method for a fixed-frequency load, wherein the fixed-frequency load is connected to an output terminal of an inverter and an AC source respectively, and the inverter supplies power to the fixed-frequency load in the following manners: a DC source is inverted and output by the inverter for inversion power supply, or an AC source connected to the output terminal of the inverter is used for bypass power supply, and the power supply switching method includes:

[0006] In the process of bypass power supply to the fixed-frequency load, detecting a bypass frequency corresponding to the output end of the inverter;

[0007] determining a bypass frequency change rate based on the bypass frequency;

[0008] Determining whether there is an abnormality in the bypass power supply based on the bypass frequency change rate;

[0009] If the bypass power supply is abnormal, the fixed-frequency load is switched from bypass power supply to inverter power supply.

[0010] Furthermore, the bypass frequency corresponding to the detected bypass voltage includes:

[0011] When the bypass frequency corresponding to the output end of the inverter starts to change on the reference frequency output by the AC source, the output end of the inverter is continuously frequency sampled based on the sampling interval duration to obtain the bypass frequency.

[0012] Further, determining the bypass frequency change rate based on the bypass frequency includes:

[0013] Acquire a current bypass frequency and a previous bypass frequency that are adjacent in a sampling interval, wherein a sampling time of the previous bypass frequency is earlier than a sampling time of the current bypass frequency;

[0014] Subtract the previous bypass frequency from the current bypass frequency and take the absolute value to get the bypass frequency change;

[0015] The bypass frequency change amount is divided by the sampling interval duration to obtain the bypass frequency change rate.

[0016] Further, determining whether the bypass power supply is abnormal based on the bypass frequency change rate includes:

[0017] If the bypass frequency change rate is greater than a preset frequency threshold and lasts for a preset time, it is determined that the bypass power supply is abnormal;

[0018] If the bypass frequency change rate is less than or equal to the preset frequency threshold, or the bypass frequency change rate is greater than the preset frequency threshold but does not continue for a preset time period, it is determined that there is no abnormality in the bypass power supply.

[0019] Further, the bypass frequency change rate includes: a bypass frequency decrease rate and a bypass frequency increase rate;

[0020] If the bypass frequency change rate is greater than a preset frequency threshold and lasts for a preset time, determining that the bypass power supply is abnormal includes:

[0021] If the bypass frequency decrease rate is greater than a preset frequency threshold and lasts for a preset time, it is determined that the bypass power supply is abnormal;

[0022] Alternatively, if the bypass frequency increase rate is greater than a preset frequency threshold and lasts for a preset time period, it is determined that the bypass power supply is abnormal.

[0023] Furthermore, the method further comprises:

[0024] Divide the preset duration by the sampling interval duration corresponding to the bypass frequency to obtain a detection number threshold;

[0025] After obtaining the bypass frequency change rate each time based on the sampling interval duration, determining whether the bypass frequency change rate is greater than a preset frequency threshold;

[0026] If the number of times that the bypass frequency change rate is continuously detected to be greater than the preset frequency threshold reaches the detection number threshold, it is determined that the bypass frequency change rate is greater than the preset frequency threshold and lasts for a preset time period.

[0027] Furthermore, the method further comprises:

[0028] Pre-acquire the bypass frequency change amount corresponding to the bypass frequency when the bypass power supply is abnormal; the bypass frequency change amount is the bypass frequency increase amount or the bypass frequency decrease amount;

[0029] Determine a bypass frequency sampling point at which the bypass frequency change amount is greater than a detection change threshold;

[0030] Determine a target bypass frequency change rate corresponding to a plurality of adjacent bypass frequency sampling points at a sampling time;

[0031] The preset frequency threshold is obtained based on the target bypass frequency change rate.

[0032] The embodiment of the present application further provides a power supply switching device for a fixed-frequency load, wherein the fixed-frequency load is connected to an output end of an inverter, and the inverter supplies power to the fixed-frequency load in the following manners: a DC source is inverted and output by the inverter for inversion power supply, or an AC source connected to the output end of the inverter is used for bypass power supply.

[0033] The power supply switching device comprises:

[0034] A detection unit, used to detect a bypass frequency corresponding to an output end of the inverter during bypass power supply to the fixed-frequency load;

[0035] A first determining unit, configured to determine a bypass frequency change rate based on the bypass frequency;

[0036] A second determining unit, configured to determine whether the bypass power supply is abnormal based on the bypass frequency change rate;

[0037] The switching unit is used to switch the fixed-frequency load from bypass power supply to inverter power supply if an abnormality occurs in the bypass power supply.

[0038] The embodiment of the present application further provides a power supply switching device for a fixed-frequency load, comprising:

[0039] CPU, memory, input and output interface, wired or wireless network interface, power supply;

[0040] The memory is a short-term storage memory or a persistent storage memory;

[0041] The central processor is configured to communicate with the memory, and execute the instruction operation in the memory on the control plane function entity to perform the above method.

[0042] An embodiment of the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium includes instructions. When the instructions are executed on a computer, the computer executes the method described above.

[0043] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0044] In the embodiment of the present application, the fixed-frequency load is connected to the output end of the inverter, and the inverter supplies power to the fixed-frequency load in the following manner: the DC source is inverted and output by the inverter for inverter power supply, or the AC source connected to the output end of the inverter is bypass powered. The power supply switching method includes: in the process of bypass power supply to the fixed-frequency load, detecting the bypass frequency corresponding to the output end of the inverter; determining the bypass frequency change rate based on the bypass frequency; determining whether the bypass power supply is abnormal based on the bypass frequency change rate; if the bypass power supply is abnormal, switching the fixed-frequency load from bypass power supply to inverter power supply. There is no need to detect the bypass voltage at the output end of the inverter to avoid the interference of the induced electromotive force generated by the fixed-frequency load when the bypass power supply is abnormal. By detecting the bypass frequency corresponding to the output end of the inverter, it can be quickly determined whether the bypass power supply is abnormal based on the bypass frequency change rate, so that when the bypass power supply is abnormal, the fixed-frequency load can be quickly switched from bypass power supply to inverter power supply, effectively shortening the power supply switching time. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0046] Figure 1 A power supply system diagram of a fixed-frequency load disclosed in an embodiment of the present application;

[0047] Figure 2 A power supply switching waveform diagram of a fixed-frequency load disclosed in an embodiment of the present application;

[0048] Figure 3 A power supply switching flow chart for a fixed-frequency load disclosed in an embodiment of the present application;

[0049] Figure 4 A flowchart for determining whether bypass power supply is abnormal is disclosed in an embodiment of the present application;

[0050] Figure 5 A data fitting curve diagram when a bypass power supply is abnormal disclosed in an embodiment of the present application;

[0051] Figure 6A data fitting curve diagram of another bypass power supply abnormality disclosed in an embodiment of the present application;

[0052] Figure 7 A power supply switching waveform diagram of another fixed-frequency load disclosed in an embodiment of the present application;

[0053] Figure 8 A diagram of a power supply switching device for a fixed-frequency load disclosed in an embodiment of the present application;

[0054] Fig. 9 This is a diagram of another power supply switching device for a fixed-frequency load disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0055] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0056] In the description of the embodiments of the present application, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the embodiments of the present application.

[0057] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0058] In the embodiment of the present application, the output end of the inverter has a fixed-frequency load, which can be understood as a fixed-frequency motor load, such as Figure 1As shown, the fixed-frequency load is connected to the output end of the inverter, and the inverter supplies power to the fixed-frequency load in the following manner: the DC source is inverted and then output by the inverter, or the AC source connected to the output end of the inverter is bypass-powered; it can be understood that the AC source can be connected to the output end of the inverter through a bypass inside the inverter, or connected to the output end of the inverter through a bypass independent of the inverter, and the specifics are not limited here.

[0059] Among them, the fixed-frequency load can be a fixed-frequency spray pump with a nominal power of 7.5kW; the DC source can be a battery or a photovoltaic panel, which is not limited here; the corresponding inverter power supply is: the DC voltage of the DC power output by the DC source is converted into a DC voltage that meets the fixed-frequency load through a DC-to-DC converter (DCDC) in the inverter, and then the DC power is inverted into AC power through an inverter module (DCAC) in the inverter and output to the fixed-frequency load; the AC source can be municipal electricity or an AC power supply, which is not limited here; the corresponding bypass power supply (ECO) is that the AC source directly outputs AC power to the fixed-frequency load.

[0060] Generally, when the bypass power supply is normal, the AC source is used to bypass the fixed-frequency load. At this time, the bypass voltage at the output end of the inverter can be detected to determine whether there is an abnormality in the bypass power supply. When there is an abnormality in the bypass power supply, the fixed-frequency load is switched from bypass power supply to inverter power supply. However, when the bypass power supply is abnormal (such as AC power failure), the fixed-frequency load will generate an induced electromotive force, and the bypass virtual voltage can still be detected at the output end of the inverter. It will be difficult to quickly determine whether there is an abnormality in the bypass power supply by detecting the bypass voltage at the output end of the inverter. It is difficult to quickly switch the fixed-frequency load from bypass power supply to inverter power supply, resulting in a long switching time. Figure 2 As shown in the figure, channel 1 represents the DC input current of the DC source input inverter, channel 2 represents the bypass voltage detected at the output end of the inverter, channel 3 represents the output voltage of the output end of the inverter, and channel 4 represents the output current of the output end of the inverter. It can be seen that time a is the moment when the bypass power supply is abnormal, and time b is the moment when the bypass power supply is switched to the inverter power supply. The difference between time b and time a is 26.8ms, that is, the switching time from bypass power supply to inverter power supply is 26.8ms.

[0061] However, if the switching time is too long, it is easy to cause the fixed-frequency load to demagnetize. When the inverter switches to the inverter power supply, the fixed-frequency load needs to be re-excited. Excessive excitation current will trigger the inverter's overcurrent protection, which will eventually lead to switching failure and power failure of the fixed-frequency load. Therefore, the embodiment of the present application provides a power supply switching method, power supply switching device and medium for a fixed-frequency load, which can quickly switch the fixed-frequency load from bypass power supply to inverter power supply when an abnormality occurs in the bypass power supply, effectively shortening the power supply switching time, such as Figure 3 As shown, the specific steps include:

[0062] 301. In the process of bypass power supply to the fixed-frequency load, a bypass frequency corresponding to the output end of the inverter is detected.

[0063] When the bypass power supply is normal, the fixed-frequency load can be bypass-powered by the AC source, that is, the AC source provides a bypass voltage to the fixed-frequency load. The bypass voltage is an AC voltage with a corresponding bypass frequency. When the bypass power supply is normal, the bypass frequency is generally stable at the reference frequency output by the AC source (such as the reference frequency of the mains output is 50HZ). When the bypass power supply is abnormal, such as the AC source is powered off, the AC source fluctuates, or the power supply line is disturbed, the bypass frequency will fluctuate to a certain extent on the reference frequency, such as Figure 5 As shown, the bypass voltage and bypass frequency corresponding to the output end of the inverter are brushed. The horizontal axis in the figure represents the corresponding bypass frequency sampling point. The sampling interval of adjacent bypass frequency sampling points can be 52us, and the vertical axis represents the amplitude. By brushing the bypass voltage, the bypass voltage and bypass frequency can be concentrated for comparison. It can be seen that when the bypass power supply is abnormal, although the bypass voltage does not change significantly (due to the induced electromotive force generated by the fixed-frequency load, the bypass virtual voltage can be detected at the output end of the inverter), the bypass frequency has obvious fluctuations (rapid decline and rapid rise); therefore, in the embodiment of the present application, in the process of bypass power supply to the fixed-frequency load, the bypass frequency corresponding to the output end of the inverter can be detected, and whether the bypass power supply is abnormal can be determined based on the bypass frequency.

[0064] The bypass frequency corresponding to the bypass voltage can be detected as follows: when the bypass frequency corresponding to the output end of the inverter starts to change on the reference frequency output by the AC source, the output end of the inverter is continuously sampled based on the sampling interval duration to obtain the bypass frequency. The bypass frequency corresponding to the output end of the inverter can be compared with the reference frequency output by the AC source. When the bypass frequency corresponding to the output end of the inverter fluctuates on the reference frequency (such as greater than the reference frequency or less than the reference frequency), the bypass power supply may be abnormal. At this time, the output end of the inverter is continuously sampled based on the sampling interval duration to obtain the bypass frequency, without the need to perform frequency sampling on the output end of the inverter in real time, effectively saving sampling resources.

[0065] 302. Determine a bypass frequency change rate based on the bypass frequency.

[0066] After the bypass frequency is detected, the bypass frequency change rate can be determined based on the bypass frequency. The bypass frequency change rate is the change of the bypass frequency over time. The bypass frequency change rate can be the bypass frequency decrease rate or the bypass frequency increase rate, which is not limited here. During the continuous frequency sampling process at the output end of the inverter, the bypass frequency change rate can be continuously obtained.

[0067] Determining the bypass frequency change rate based on the bypass frequency can be specifically as follows: obtaining the adjacent current bypass frequency and the previous bypass frequency in the sampling interval, the sampling time of the previous bypass frequency is earlier than the sampling time of the current bypass frequency; that is, the current bypass frequency and the previous bypass frequency are two adjacent bypass frequencies obtained by sampling during continuous frequency sampling. The bypass frequency change can be obtained by subtracting the absolute value of the previous bypass frequency from the current bypass frequency; it can be understood that if the current bypass frequency is greater than the previous bypass frequency, the bypass frequency change obtained is the bypass frequency increase; if the current bypass frequency is less than the previous bypass frequency, the bypass frequency change obtained is the bypass frequency decrease. Then, the bypass frequency change can be divided by the sampling interval duration to obtain the bypass frequency change rate; that is, the bypass frequency increase divided by the sampling interval duration can obtain the bypass frequency increase rate, and the bypass frequency decrease divided by the sampling interval duration can obtain the bypass frequency decrease rate.

[0068] 303. Determine whether the bypass power supply is abnormal based on the bypass frequency change rate.

[0069] After obtaining the bypass frequency change rate, it is possible to determine whether the bypass power supply is abnormal based on the bypass frequency change rate; it is understandable that when the bypass power supply is abnormal, such as when the AC source is powered off or the power supply line is disturbed, the bypass frequency corresponding to the output end of the inverter will fluctuate to a certain extent, that is, when the bypass frequency fluctuates greatly, it can be determined that the bypass power supply is abnormal; specifically, when the bypass frequency change rate is greater than the preset frequency threshold, it is determined that the bypass power supply is abnormal; when the bypass frequency change rate is less than or equal to the preset frequency threshold, it is determined that the bypass power supply is not abnormal; wherein, the preset frequency threshold can be obtained by actually detecting the corresponding bypass frequency change rate when the bypass power supply is abnormal; the preset frequency threshold can be 100Hz / s or 120Hz / s, which is not limited here.

[0070] 304. If the bypass power supply is abnormal, the fixed-frequency load is switched from bypass power supply to inverter power supply.

[0071] If the bypass power supply is abnormal, the fixed-frequency load will be switched from bypass power supply to inverter power supply. If the AC source is connected to the output end of the inverter through a bypass relay, the bypass relay is closed during bypass power supply; when the fixed-frequency load is switched from bypass power supply to inverter power supply, the bypass relay can be disconnected to control the inverter to invert and output AC power for inverter power supply.

[0072] It can be seen that in the embodiment of the present application, the fixed-frequency load is connected to the output end of the inverter, and the power supply mode of the fixed-frequency load is: the DC source is inverted and output by the inverter for inverter power supply, or the AC source connected to the output end of the inverter is bypass powered, and the power supply switching method includes: in the process of bypass power supply to the fixed-frequency load, the bypass frequency corresponding to the output end of the inverter is detected; the bypass frequency change rate is determined based on the bypass frequency; whether the bypass power supply is abnormal based on the bypass frequency change rate is determined; if the bypass power supply is abnormal, the fixed-frequency load is switched from bypass power supply to inverter power supply. There is no need to detect the bypass voltage at the output end of the inverter to avoid the interference of the induced electromotive force generated by the fixed-frequency load when the bypass power supply is abnormal. By detecting the bypass frequency corresponding to the output end of the inverter, it can be quickly determined whether the bypass power supply is abnormal based on the bypass frequency change rate, so that when the bypass power supply is abnormal, the fixed-frequency load can be quickly switched from bypass power supply to inverter power supply, effectively shortening the power supply switching time.

[0073] Further, in the embodiment of the present application, the bypass frequency change amount corresponding to the bypass frequency when the bypass power supply is abnormal can be obtained in advance to obtain a preset frequency threshold, which can reflect the actual bypass frequency change rate when the bypass power supply is abnormal. Then, by comparing the bypass frequency change rate with the preset frequency threshold, it is possible to accurately determine whether the bypass power supply is abnormal; Figure 4 As shown, the specific steps include:

[0074] 401. Obtain in advance a bypass frequency change amount corresponding to the bypass frequency when an abnormality occurs in the bypass power supply, and obtain a preset frequency threshold.

[0075] In an embodiment of the present application, the bypass frequency change corresponding to the bypass frequency when an abnormality occurs in the bypass power supply can be obtained in advance; the bypass frequency change is the bypass frequency increase or the bypass frequency decrease; the bypass frequency sampling point where the bypass frequency change is greater than the detection change threshold is determined; the detection change threshold is used to screen the bypass frequency sampling points with a large bypass frequency change, and the detection change threshold can be 0.1HZ or 0.2HZ, which is not limited here. Determine a target bypass frequency change rate corresponding to a plurality of adjacent bypass frequency sampling points at a sampling time; wherein, a plurality of adjacent bypass frequency sampling points can be taken during the process of bypass frequency reduction, and among the plurality of bypass frequency sampling points, a first bypass frequency of a bypass frequency sampling point with an earliest sampling time is subtracted from a second bypass frequency of a bypass frequency sampling point with a latest sampling time to obtain a corresponding bypass frequency reduction amount, and then, the bypass frequency reduction amount is divided by a sampling interval duration between the first bypass frequency and the second bypass frequency to obtain a target bypass frequency change rate; then, a preset frequency threshold can be obtained based on the target bypass frequency change rate, such as taking half or one third of the target bypass frequency change rate as the preset frequency threshold.

[0076] Among them, it can be Figure 5 The bypass frequency in is brushed and the corresponding bypass frequency change is obtained (the bypass frequency change is the bypass frequency decrease), such as Figure 6 As shown, the corresponding detection change threshold (detection threshold) is 0.1HZ. By comparing the bypass frequency change with the detection change threshold, the bypass frequency sampling point where the bypass frequency change is greater than the detection change threshold can be obtained. At this time, the corresponding target bypass frequency change rate can be calculated by taking multiple adjacent bypass frequency sampling points during the descent process; for example, the bypass frequency sampling points can be taken: 246 points to 256 points, and the corresponding bypass frequency change process is 48.235Hz→46.9392Hz. The calculation process of the target bypass frequency change rate is as follows: the number of bypass frequency sampling points = 256-246+1 = 11; the sampling interval corresponding to 11 points = 11 / 400*20ms*10 = 5.5ms, where 400 means a total of 400 bypass frequency sampling points, 20ms means continuous sampling for 20ms, that is, 400 points are sampled within 20ms, and 10 means ten-tenths of a frequency; the corresponding target bypass frequency change rate = (48.235Hz–46.9392Hz) / 5.5ms = 0.2356Hz / ms = 235.6Hz / s = 0.01227Hz / 52us. It can be seen that when the bypass power supply is abnormal, the target bypass frequency change rate is 235.6Hz / s, while the normal frequency tracking rate of the inverter is 2Hz / s, that is, when the bypass power supply is abnormal, the bypass frequency change rate is much greater than the frequency tracking rate. Frequency tracking will not affect the result of detecting whether an abnormality occurs based on the bypass frequency change rate. The bypass frequency change rate can be used to detect whether the bypass power supply is abnormal. Then, based on the target bypass frequency change rate of 235.6Hz / s (0.01227Hz / 52us), the preset frequency threshold can be taken as 0.07Hz / 52us (about 134.6Hz / s).

[0077] 402. If the bypass frequency change rate is greater than a preset frequency threshold and lasts for a preset time period, it is determined that the bypass power supply is abnormal.

[0078] After obtaining the bypass frequency change rate, the bypass frequency change rate can be compared with the preset frequency threshold. If the bypass frequency change rate is greater than the preset frequency threshold and continues for a preset time, it is determined that the bypass power supply is abnormal. Among them, the preset time can be 0.65ms or 0.7ms, which is not limited here. It can be understood that when the bypass frequency fluctuates, the bypass frequency will decrease and the bypass frequency will increase; therefore, the bypass frequency change rate includes: the bypass frequency decrease rate and the bypass frequency increase rate; that is, if the bypass frequency decrease rate is greater than the preset frequency threshold and continues for a preset time, it is determined that the bypass power supply is abnormal; or, if the bypass frequency increase rate is greater than the preset frequency threshold and continues for a preset time, it is determined that the bypass power supply is abnormal.

[0079] Specifically, it can be determined whether the bypass frequency change rate is greater than the preset frequency threshold and lasts for a preset time by continuously detecting whether the number of times the bypass frequency change rate is greater than the preset frequency threshold reaches the detection number threshold, as shown in the following steps 4021 and 4022:

[0080] 4021. Divide the preset duration by the sampling interval duration corresponding to the bypass frequency to obtain a detection number threshold.

[0081] In an embodiment of the present application, a preset duration can be divided by the sampling interval duration corresponding to the bypass frequency to obtain a detection number threshold. Among them, the preset duration can be divided by the sampling interval duration corresponding to the bypass frequency and rounded to obtain a detection number threshold, such as 2.6 is rounded to 3, 3.1 is rounded to 4, and the obtained detection number threshold multiplied by the sampling interval duration is greater than or equal to the preset duration. The obtained detection number threshold can be 3 times or 4 times, which is not specifically limited here. Then, after the bypass frequency change rate is obtained each time based on the sampling interval duration, it can be determined whether the bypass frequency change rate is greater than the preset frequency threshold, that is, after each sampling obtains the bypass frequency, the corresponding bypass frequency change rate is obtained, and then it is determined whether the bypass frequency change rate is greater than the preset frequency threshold in this detection.

[0082] 4022. If the number of times that the bypass frequency change rate is continuously detected to be greater than the preset frequency threshold reaches the detection number threshold, it is determined that the bypass frequency change rate is greater than the preset frequency threshold and lasts for a preset time period.

[0083] If the number of times that the bypass frequency change rate is detected to be greater than the preset frequency threshold reaches the detection number threshold, it is determined that the bypass frequency change rate is greater than the preset frequency threshold and lasts for a preset time. If, during the process of the bypass frequency decreasing, the bypass frequency decreasing rate is detected to be large for many consecutive times, it can be determined that the bypass power supply is abnormal; or, during the process of the bypass frequency increasing, the bypass frequency increasing rate is detected to be large for many consecutive times, it can be determined that the bypass power supply is abnormal.

[0084] 403. If the bypass frequency change rate is less than or equal to the preset frequency threshold, or the bypass frequency change rate is greater than the preset frequency threshold but does not continue for a preset time period, it is determined that there is no abnormality in the bypass power supply.

[0085] If the bypass frequency change rate is less than or equal to the preset frequency threshold, or the bypass frequency change rate is greater than the preset frequency threshold but does not continue for a preset time, it is determined that there is no abnormality in the bypass power supply, that is, the bypass power supply continues to be provided to the fixed-frequency load.

[0086] In the embodiment of the present application, by detecting the bypass frequency corresponding to the output end of the inverter, it is possible to quickly determine whether the bypass power supply is abnormal based on the bypass frequency change rate, so as to quickly switch to the inverter power supply when the bypass power supply is abnormal. The corresponding waveform is as follows: Figure 7 As shown in the figure, channel 1 is the DC input current of the DC source input inverter, channel 2 is the output voltage of the output end of the inverter, channel 3 is the output current of the output end of the inverter, time A is the moment when the bypass power supply is abnormal, and time B is the moment when the bypass power supply is switched to the inverter power supply; it can be seen that when the inverter is carrying a fixed-frequency load, the switching time from bypass power supply to inverter power supply is 8.6ms, which can ensure normal load switching of the inverter and the fixed-frequency load will not lose power during the switching process.

[0087] In an practicable manner, harmonic interference can be injected into the AC source to verify whether the bypass power supply is abnormal based on the bypass frequency change rate in the embodiment of the present application and whether there will be a false detection. The corresponding verification results are shown in the following table:

[0088]

[0089] Among them, 2Hz / s frequency change means that the reference frequency (such as 50HZ) of the AC source output fluctuates up and down by 2Hz / s; full-load steady state means that the load rate carried by the output end of the inverter is 100% full load. In addition to fixed-frequency load, the output end of the inverter can also carry variable-frequency load (variable-frequency primary circulation pump load) and fan load, etc.; full-load sudden addition and removal means suddenly taking on full load or suddenly removing full load; bypass THDU means: total harmonic distortion rate of bypass voltage; it can be seen that the total harmonic injection of the AC source input within 7% will not be misdetected.

[0090] In another feasible manner, the switching time of switching from bypass power supply to inverter power supply can also be verified when the output end of the inverter has different load rates. The verification results are shown in the following table:

[0091]

[0092] It can be seen that under different load combinations and load rates, the bypass power supply can be quickly switched to the inverter power supply.

[0093] The present application also provides a power supply switching device for a fixed frequency load, such as Figure 8 As shown, the fixed-frequency load is connected to the output end of the inverter, and the inverter supplies power to the fixed-frequency load in the following manner: a DC source is inverted and output by the inverter for inversion power supply, or an AC source connected to the output end of the inverter is used for bypass power supply, and the power supply switching device includes:

[0094] The detection unit 801 is used to detect the bypass frequency corresponding to the output end of the inverter during the process of bypass power supply to the fixed-frequency load;

[0095] A first determining unit 802 is configured to determine a bypass frequency change rate based on the bypass frequency;

[0096] A second determining unit 803 is used to determine whether the bypass power supply is abnormal based on the bypass frequency change rate;

[0097] The switching unit 804 is used to switch the fixed-frequency load from bypass power supply to inverter power supply if an abnormality occurs in the bypass power supply.

[0098] The embodiment of the present application also provides a power supply switching device 900 for a fixed frequency load, such as Fig. 9 As shown, the power switching device 900 of the embodiment of the present application may include one or more central processing units (CPU) 901 and a memory 902 , wherein the memory 902 stores one or more application programs or data.

[0099] The memory 902 may be a volatile storage or a persistent storage. The program stored in the memory 902 may include one or more modules, each of which may include a series of instruction operations in the electronic device. Furthermore, the central processor 901 may be configured to communicate with the memory 902 and execute a series of instruction operations in the memory 902 on the power supply switching device 900.

[0100] The power switching device 900 may also include one or more power supplies 905, one or more wired or wireless network interfaces 904, one or more input and output interfaces 903, and / or one or more operating systems, such as Windows ServerTM, Mac OS XTM, UnixTM, LinuxTM, FreeBSDTM, etc.

[0101] The central processing unit 901 can execute the operations performed by the aforementioned first aspect or any specific method embodiment of the first aspect, and the details will not be repeated here.

[0102] An embodiment of the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium includes instructions. When the instructions are executed on a computer, the computer executes the method described above.

[0103] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0104] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0105] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0106] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0107] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, read-only memory), random access memory (RAM, random access memory), disk or optical disk and other media that can store program code.

Claims

1. A power supply switching method for a fixed frequency load, characterized in that: The fixed-frequency load is connected to the output end of the inverter. The inverter supplies power to the fixed-frequency load in the following manner: a DC source is inverted and output by the inverter for inversion power supply, or an AC source connected to the output end of the inverter is used for bypass power supply. The power supply switching method includes: In the process of bypass power supply to the fixed-frequency load, detecting a bypass frequency corresponding to the output end of the inverter; determining a bypass frequency change rate based on the bypass frequency; Determining whether there is an abnormality in the bypass power supply based on the bypass frequency change rate; If the bypass power supply is abnormal, the fixed-frequency load is switched from bypass power supply to inverter power supply.

2. The power supply switching method according to claim 1, characterized in that: The bypass frequency corresponding to the detected bypass voltage includes: When the bypass frequency corresponding to the output end of the inverter starts to change on the reference frequency output by the AC source, the output end of the inverter is continuously frequency sampled based on the sampling interval duration to obtain the bypass frequency.

3. The power supply switching method according to claim 2, characterized in that: Determining the bypass frequency change rate based on the bypass frequency includes: Acquire a current bypass frequency and a previous bypass frequency that are adjacent in a sampling interval, wherein a sampling time of the previous bypass frequency is earlier than a sampling time of the current bypass frequency; Subtract the previous bypass frequency from the current bypass frequency and take an absolute value to obtain a bypass frequency change; The bypass frequency change amount is divided by the sampling interval duration to obtain the bypass frequency change rate.

4. The power supply switching method according to claim 1, characterized in that: The determining whether the bypass power supply is abnormal based on the bypass frequency change rate includes: If the bypass frequency change rate is greater than a preset frequency threshold and lasts for a preset time, it is determined that the bypass power supply is abnormal; If the bypass frequency change rate is less than or equal to the preset frequency threshold, or the bypass frequency change rate is greater than the preset frequency threshold but does not continue for a preset time period, it is determined that there is no abnormality in the bypass power supply.

5. The power supply switching method according to claim 4, characterized in that: The bypass frequency change rate includes: a bypass frequency decrease rate and a bypass frequency increase rate; If the bypass frequency change rate is greater than a preset frequency threshold and lasts for a preset time, determining that the bypass power supply is abnormal includes: If the bypass frequency decrease rate is greater than a preset frequency threshold and lasts for a preset time, it is determined that the bypass power supply is abnormal; Alternatively, if the bypass frequency increase rate is greater than a preset frequency threshold and lasts for a preset time period, it is determined that the bypass power supply is abnormal.

6. The power supply switching method according to claim 4, characterized in that: The method further comprises: Divide the preset duration by the sampling interval duration corresponding to the bypass frequency to obtain a detection number threshold; After obtaining the bypass frequency change rate each time based on the sampling interval duration, determining whether the bypass frequency change rate is greater than a preset frequency threshold; If the number of times that the bypass frequency change rate is continuously detected to be greater than the preset frequency threshold reaches the detection number threshold, it is determined that the bypass frequency change rate is greater than the preset frequency threshold and lasts for a preset time period.

7. The power supply switching method according to claim 4, characterized in that: The method further comprises: Pre-acquire the bypass frequency change amount corresponding to the bypass frequency when the bypass power supply is abnormal; the bypass frequency change amount is the bypass frequency increase amount or the bypass frequency decrease amount; Determine a bypass frequency sampling point at which the bypass frequency change amount is greater than a detection change threshold; Determine a target bypass frequency change rate corresponding to a plurality of adjacent bypass frequency sampling points at a sampling time; The preset frequency threshold is obtained based on the target bypass frequency change rate.

8. A power supply switching device for a fixed frequency load, characterized in that: The fixed-frequency load is connected to the output end of the inverter. The inverter supplies power to the fixed-frequency load in the following manner: a DC source is inverted and output by the inverter for inversion power supply, or an AC source connected to the output end of the inverter is used for bypass power supply. The power supply switching device includes: A detection unit, used to detect a bypass frequency corresponding to an output end of the inverter during bypass power supply to the fixed-frequency load; A first determining unit, configured to determine a bypass frequency change rate based on the bypass frequency; A second determining unit, configured to determine whether the bypass power supply is abnormal based on the bypass frequency change rate; The switching unit is used to switch the fixed-frequency load from bypass power supply to inverter power supply if an abnormality occurs in the bypass power supply.

9. A power supply switching device for a fixed frequency load, characterized in that: include: CPU, memory, input and output interface, wired or wireless network interface, power supply; The memory is a transient storage memory or a persistent storage memory; The central processor is configured to communicate with the memory, and execute instruction operations in the memory on a control plane function entity to perform the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium comprises instructions, and when the instructions are executed on a computer, the computer is caused to perform the method according to any one of claims 1 to 7.

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