Detection Method, Device and Medium for Open Circuit Fault in UPS Parallel System

Abstract

The present invention provides a detection method for open - circuit faults in a UPS parallel system, including: each UPS slave receives the host inverter output voltage and the host output power sent by the UPS master; each UPS slave judges the absolute value of the difference between the host inverter output voltage and the slave inverter output voltage. When the absolute value of the difference is greater than the error threshold, it enters step 3; the UPS slave judges whether the difference is greater than the error threshold. If not, it enters step 4; if so, it judges whether the slave output power is greater than the power threshold. If it is, it is determined that there is a fault at the output end of the UPS master; otherwise, the current - sharing loop integral quantity is cleared; the UPS slave judges whether the difference is less than the negative of the error threshold. If not, the process ends; if so, it judges whether the host output power is greater than the power threshold. If it is, it is determined that there is a fault at the output end of the UPS slave; otherwise, the current - sharing loop integral quantity is cleared. The present invention also provides an electronic device and a medium, which can quickly detect the fault point.

Description

Technical Field

[0001] The present invention relates to the technical field of fault detection, and in particular to a detection method, device and medium for open circuit faults in a UPS parallel system. Background Art

[0002] UPS, i.e., Uninterruptible Power Supply, is an uninterruptible power supply containing an energy storage device. It is a system device that converts direct current into commercial power. It is mainly used to provide uninterrupted power to some devices with high requirements for power stability. Therefore, how to improve the reliability of USP has become an urgent problem to be solved in this field.

[0003] In the prior art, in order to solve the reliability of the UPS system, a UPS parallel scheme is usually adopted. UPS parallel means that two or more UPSs work simultaneously, so that the relevant loads can be dispersed. With less responsibility, the probability of failure can naturally be reduced. This is because when one machine fails, other intact power supplies will take over the responsibility of the faulty power supply, and the operation of the entire system will not be affected in a short time. When UPSs are paralleled, it is necessary to ensure that the output lines of each phase of each UPS can be reliably connected together, so that the normal operation of the machines can be ensured during parallel operation.

[0004] As Figure 1 shown, when an open circuit fault occurs in the output line, it can be divided into two categories according to the fault point:

[0005] 1. If the open circuit point occurs at the output end of the UPS main unit, it belongs to the output line open circuit fault of fault type 1;

[0006] 2. If the open circuit point occurs at the output end of the UPS slave unit, it belongs to the output line open circuit fault of fault type 2.

[0007] Traditional power supply fault detection is carried out manually. When a machine has failed, it cannot be detected in the first time, and the specific fault location cannot be intuitively located. It is necessary to check each point one by one, which takes a relatively long time for the check and detection, consumes a lot of manpower, has low detection efficiency, and the accuracy of power supply fault detection also needs to be improved. Summary of the Invention

[0008] To solve the above problems, the present invention provides a detection method for open circuit faults in a UPS parallel system, which can quickly detect the fault point, save manpower, and improve the detection efficiency and accuracy.

[0009] The present invention is realized by the following technical solutions:

[0010] The present invention provides a detection method for open - circuit faults in a UPS parallel system, where the UPS parallel system needs to provide a UPS main unit, a plurality of UPS slave units, and at least one load; the method includes the following steps:

[0011] Step 1, each UPS slave unit receives the host inverter output voltage and the host output power sent by the UPS main unit;

[0012] Step 2, each UPS slave unit judges the absolute value of the difference between the host inverter output voltage and its own slave inverter output voltage. When the absolute value of the difference is greater than the error threshold, it enters Step 3;

[0013] Step 3, the UPS slave unit judges whether the difference is greater than the error threshold. If not, it enters Step 4; if so, it continues to judge whether the slave output power is greater than the power threshold. If it is, it is determined that a line disconnection fault has occurred at the output end of the UPS main unit; if not, it clears the current - sharing loop integral of this UPS slave unit and continues to wait for the fault condition to be met for re - judgment;

[0014] Step 4, the UPS slave unit judges whether the difference is less than the negative of the error threshold. If not, the process ends; if so, it continues to judge whether the host output power is greater than the power threshold. If it is, it is determined that a line disconnection fault has occurred at the output end of this UPS slave unit; if not, it clears the current - sharing loop integral of this UPS slave unit and continues to wait for the fault condition to be met for re - judgment.

[0015] Further, in Step 1, the UPS main unit sends the host inverter output voltage and the host output power to each UPS slave unit through the parallel CAN communication bus.

[0016] Further, Step 2 specifically includes:

[0017] Step 21, each UPS slave unit calculates the absolute value of the difference between the host inverter output voltage and its own slave inverter output voltage;

[0018] Step 22, compare the absolute value of the difference with the error threshold. If the absolute value of the difference is greater than the error threshold, confirm the comparison result and count the number of times, and enter Step 23; if the absolute value of the difference is not greater than the error threshold, clear the count of the comparison result and end the process;

[0019] Step 23, judge whether the number of times counted is greater than or equal to the preset number of times. If it is, enter Step 3; if not, repeat Steps 22 - 23.

[0020] Further, after it is determined that a line disconnection fault has occurred at the output end of the UPS main unit in Step 3, it further includes:

[0021] Step 31: The slave UPS sets the fault flag variable and sends it to the master UPS via the parallel operation CAN communication bus.

[0022] Step 32: After receiving the feedback information sent by the master UPS after receiving the set fault flag variable, the slave UPS.

[0023] Step 33: The slave UPS stops outputting the fault flag variable to the master UPS.

[0024] Step 34: Disconnect the output of the master UPS and exit the UPS parallel operation system, and select one of the slave UPSs to continue working as the master UPS.

[0025] Step 35: After the slave UPS receives the set reset variable sent via the parallel operation CAN communication bus after the line disconnection fault of the master UPS is repaired and the master UPS rejoins the UPS parallel operation system.

[0026] Step 36: After the slave UPS detects that the reset variable is set, it resets the fault flag variable.

[0027] Further, after determining that a line disconnection fault has occurred at the output end of the slave UPS in step 4, it further includes:

[0028] Disconnect the output of the slave UPS with the line disconnection fault and exit the UPS parallel operation system, and perform repairs without affecting the operation of the master UPS and other slave UPSs without line disconnection faults. After the slave UPS with the line disconnection fault is repaired, it rejoins the UPS parallel operation system.

[0029] Further, the error threshold is any value in 2v - 10v.

[0030] Further, the error threshold is 3v.

[0031] Further, the power threshold is R% of the rated output power of the slave UPS, where R is a positive number with 0 < R ≤ 10.

[0032] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the detection method for open circuit faults in the UPS parallel operation system as described above.

[0033] The present invention also provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, it implements the detection method for open circuit faults in the UPS parallel operation system as described above.

[0034] The beneficial effects of the present invention are:

[0035] The present invention determines whether the output line disconnection fault point occurs in the UPS host or the corresponding UPS slave by comparing the difference between the inverter output voltage of the host and the inverter output voltage of each slave, comparing the output power of the slave and the power threshold value, and comparing the output power of the host and the power threshold value. Since the data is compared in real time, when a fault occurs in the machine, it can be detected immediately. Through numerical comparison, the detection can be carried out quickly and the specific fault location can be visually located; there is no need to check each point one by one, which reduces the troubleshooting and detection time, saves manpower, and improves the detection efficiency and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0037] Figure 1 It is a schematic diagram of the output line open circuit fault of the UPS parallel system (the current sharing loop is not shown).

[0038] Figure 2 It is a block diagram of the control principle of the outer loop of the UPS host parallel control.

[0039] Figure 3 It is a block diagram of the control principle of the outer loop of the UPS slave parallel control.

[0040] Figure 4 It is a flowchart of the detection method for the open circuit fault applied to the UPS parallel system provided by the embodiment of the present invention.

[0041] Figure 5 It is a schematic diagram of the processing logic after the UPS slave detects that a line disconnection fault has occurred at the output end of the UPS host.

[0042] Figure 6 It is a schematic diagram of the processing logic when the UPS host receives the notice from the UPS slave that a line disconnection fault has occurred at the output end.

[0043] Figure 7 A schematic diagram of an electronic device provided by the embodiment of the present invention.

[0044] Figure 8 A schematic diagram of a computer-readable storage medium provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0046] 1. As Figure 1-3 shown, a brief introduction to the current sharing principle of the UPS parallel system:

[0047] Output average current reference (Out_Avg_Curt_Ref) of the UPS parallel system: (Understood as the average value of the output currents of each UPS)

[0048] Out_Avg_Curt_Ref = (Im + I1 + I2 + … + In) / (n + 1); (n = 1, 2, 3 …) Formula 1

[0049] As Figure 1 shown in the label, Im is the output current of the UPS main unit, I1 is the output current of the first UPS slave unit, I2 is the output current of the second UPS slave unit, and In is the output current of the nth UPS slave unit;

[0050] As Figure 2 shown, the effective value reference of the main inverter output voltage of the UPS main unit directly determines the magnitude of the main inverter output voltage of the UPS main unit, and also directly determines the magnitude of the inverter output voltage of the UPS parallel system at steady state. When the UPS is in parallel operation, if the phases are consistent, the output current sharing effect can be directly achieved by adjusting the amplitude of the inverter output voltage of each machine, realizing the average distribution of the load. As Figure 2 shown, the output of the current sharing loop is directly added to the effective value reference terminal of the inverter output voltage, which will directly affect the inverter output voltage of the machine. The reason why the current sharing loop is not added to the UPS main unit is to ensure that the overall voltage of the UPS parallel system is clamped at the mains voltage.

[0051] As Figure 3As shown, different from the UPS main unit, the effective value reference of the inverter output voltage of the UPS slave unit and the output value of its current sharing loop PI controller jointly determine the magnitude of the final inverter output voltage of the UPS slave unit; after the phase synchronization of the inverter output voltages among all UPSs is completed, the inverter output voltages of each UPS slave unit are controlled through the regulation of the current sharing loop, so as to achieve the average control of the output currents among all UPSs in the UPS parallel system. The reason for adding the current sharing loop to the UPS slave unit is to achieve the goal of output current sharing in the UPS parallel system. The UPS slave unit adjusts its own voltage through the current sharing loop to ensure that its output current is consistent with the average output current of the UPS parallel system.

[0052] 2. Influence of output line disconnection fault on the UPS parallel system:

[0053] Analyze the fault phenomena according to the fault types:

[0054] Analysis of assumed conditions: A UPS parallel system composed of N UPSs in parallel includes 1 UPS main unit and (N - 1) UPS slave units. The total output power of the current UPS parallel system is M kilowatts (M > 0). It can be known that the output power of each UPS under normal current sharing in the current UPS parallel system is (M / N) kilowatts.

[0055] (1) Analysis of the condition of the output line disconnection at the main unit end:

[0056] If the output line of the UPS host is disconnected, the output power of the UPS host will drop from (M / N) kW to zero, and the other (N - 1) UPS slave units will bear the power of M kW. It can be deduced that the output power of each UPS slave unit will increase from (M / N) kW to [M / (N - 1)] kW; when the total load of the UPS parallel system remains unchanged, the output average current reference (Out_Avg_Curt_Ref) of the UPS host and each UPS slave unit will remain unchanged; when the load of the UPS host is disconnected, the output power of the other UPS slave units will increase passively, resulting in an increase in the output average current feedback (Out_Avg_Curt_Fdb) of the UPS slave units. When the output average current reference and the output average current feedback of the UPS slave units are subtracted, a negative average current error (Avg_Curt_Err) will be generated. The current sharing loop PI controller of the UPS slave unit will calculate based on the output average current error and generate a negative inverter output voltage adjustment amount. By adjusting the inverter output voltage of the UPS slave unit downward through the current sharing loop PI controller, the inverter output voltage of the UPS slave unit will continue to drop, while the control of the UPS host without the adjustment of the current sharing loop will maintain the inverter output voltage same as the mains voltage; so when the inverter output voltage of the UPS slave unit is lower than the inverter output voltage of the UPS host by a certain range until the low-voltage protection exits the UPS parallel system, this can be used as the judgment condition for the disconnection of the output line of the UPS host.

[0057] (2) Analysis of the disconnection condition of the output line at the slave unit end:

[0058] If the output lines of K UPS slave units (K = 1, 2, 3... (N - 1)) are disconnected, the output power of the UPS master unit will rise from (M / N) kilowatts to [M / (N - K)] kilowatts, and the output power of the UPS slave unit with the disconnected output line will drop from (M / N) kilowatts to 0, resulting in the reduction of the output average current feedback (Out_Avg_Curt_Fdb) of the UPS slave unit to 0. When the total load of the UPS parallel system remains unchanged, the output average current reference (Out_Avg_Curt_Ref) of the UPS master unit and each UPS slave unit will remain unchanged; the subtraction calculation between the output average current reference and the output average current feedback of the UPS slave unit will generate a positive average current error (Avg_Curt_Err). The current sharing loop PI controller of the UPS slave unit will calculate a positive inverter output voltage adjustment amount based on the output average current error, and increase the slave inverter output voltage of the UPS slave unit through the current sharing loop PI controller, which will cause the slave inverter output voltage of the UPS slave unit to continuously rise. However, the main UPS unit control without the adjustment of the current sharing loop will maintain the inverter output voltage equal to the mains voltage; so when the slave inverter output voltage is higher than the master inverter output voltage by a certain range until the high-voltage protection exits the UPS parallel system, this can be used as the judgment condition for the disconnection of the slave output line.

[0059] 3. As Figure 4 shown, the embodiment of the present invention provides a detection method for open-circuit faults in a UPS parallel system. The UPS parallel system needs to provide a UPS master unit, a plurality of UPS slave units, and at least one load; there are certain parameter differences in the hardware of each UPS in the UPS parallel system, so there will be a certain error in the actual sampling value of the output average current of each UPS. When the UPS in the UPS parallel system is in the no-load state, the theoretical output average current reference value is zero at this time, but due to the sampling error caused by hardware differences, the actual average current reference of each UPS is not zero at this time. After the adjustment of the current sharing loop PI controller of the UPS slave unit, it will cause a voltage difference between the voltage of the slave unit itself and the voltage of the master unit. To avoid misjudgment of output line disconnection faults caused by this situation, a condition that there must be a certain power load is added to ensure the accuracy of fault detection.

[0060] The method includes the following steps:

[0061] Step 1: Each UPS slave unit receives the master inverter output voltage and the master output power sent by the UPS master unit.

[0062] In this embodiment, in step 1, the UPS host sends the host inverter output voltage and the host output power to each UPS slave via the parallel CAN communication bus; the fault judgment logic is executed by each UPS slave and not by the UPS host. Therefore, the data of the UPS host for fault determination (the host inverter output voltage and the host output power) need to be sent to each UPS slave for analysis and processing, so as to ensure that each UPS slave has corresponding data for determination.

[0063] Step 2: Each UPS slave judges the absolute value of the difference (Volt_Err) between the host inverter output voltage (Volt_Master) and its own slave inverter output voltage (Volt_Slave). When the absolute value of the difference is greater than the error threshold (Err_Limit (X>Err_Limit>0, X is a positive number greater than 0)), it enters step 3; (volt_Err = fabs(Volt_Master – Volt_Slave), fabs() is the floating-point absolute value function); the error threshold is any value between 2V and 10V. The smaller the value of the error threshold (Err_Limit), the faster the fault detection, but the detection reliability decreases; preferably, the error threshold is 3V. 3V can not only ensure quick detection of faults but also improve the detection reliability. In this embodiment, 3V is taken as an example for illustration.

[0064] In this embodiment, step 2 specifically includes:

[0065] Step 21: Each UPS slave calculates the absolute value of the difference between the host inverter output voltage and its own slave inverter output voltage.

[0066] Step 22: Compare the absolute value of the difference with the error threshold. If the absolute value of the difference is greater than the error threshold, confirm the comparison result and count the number of times, and enter step 23; if the absolute value of the difference is not greater than the error threshold, clear the count of the comparison result and end the process;

[0067] Step 23: Judge whether the counted number of times is greater than or equal to the preset number of times. If so, enter step 3; if not, repeat steps 22 - 23. Conducting multiple comparison judgments is to improve the accuracy and avoid errors.

[0068] Step 3. The UPS slave determines whether the difference is greater than the error threshold. If not, it means that (host inverter output voltage - slave inverter output voltage) ≤ 3V, and then it enters Step 4. If so, it means that (host inverter output voltage - slave inverter output voltage) > 3V. According to the above analysis conclusion of the disconnection condition of the host-side output line, it is initially determined that a line disconnection fault has occurred at the output end of the UPS host. To further confirm the accuracy of the result, it is necessary to ensure that there is a certain load on the current machine to eliminate the misjudgment caused by the calculation error under no-load conditions. Under the condition of (host inverter output voltage - slave inverter output voltage) > 3V, continue to judge whether the output power of the slave is greater than the power threshold (Pw watts). The power threshold is R% of the rated output power of the UPS slave, where R is a positive number with 0 < R ≤ 10. Preferably, the power threshold is 200W. If so, it is determined that a line disconnection fault has occurred at the output end of the UPS host. If not, clear the current sharing loop integral of this UPS slave and continue to wait for the fault condition to be met for re-judgment;

[0069] As Figure 5-6 shown, in this embodiment, after it is determined in Step 3 that a line disconnection fault has occurred at the output end of the UPS host, it further includes:

[0070] Step 31. The UPS slave sets the fault flag variable (Maser_Out_Line_Brk_Err) and sends it to the UPS host through the parallel CAN communication bus. Since the fault judgment logic is executed by the UPS slave and not by the UPS host, the UPS slave needs to inform the UPS host of this fault when it detects a line disconnection fault at the output end of the UPS host;

[0071] Step 32. The UPS slave receives the feedback information sent after the UPS host receives the set fault flag variable. After detecting that the fault flag variable is set, the UPS host knows that a line disconnection fault has occurred at its own output end;

[0072] Step 33. The UPS slave stops outputting the fault flag variable of the UPS host;

[0073] Step 34. Disconnect the output of the UPS host and exit the UPS parallel system, and select one of the UPS slaves to continue working as the UPS host. The new UPS host is generated from the remaining UPS slaves according to the master-slave competition mechanism;

[0074] Step 35. The UPS slave receives the set reset variable (Master_Out_Line_Err_Rese) sent through the parallel CAN communication bus after the line disconnection fault of the UPS host is repaired and it rejoins the UPS parallel system;

[0075] Step 36: After the slave UPS detects that the reset variable is set, it resets the fault flag variable. As Figure 5 shown, if a line disconnection fault occurs at the output end of the master UPS, when the master UPS receives the fault notification from the slave UPS, it will exit the UPS parallel system. At this time, other normal slave UPSs in the UPS parallel system will generate a new master according to the master-slave competition mechanism. Therefore, in the newly formed UPS parallel system, other slave UPSs will normally enter the "No" branch and wait for the faulty master UPS to confirm the fault information and then set the Master_Out_Line_Err_Reset; after other normal machines detect that this variable is set, they reset the Master_Out_Line_Brk_Err.

[0076] Step 4: The slave UPS determines whether the difference is less than the negative of the error threshold. If not, it means that -3 ≤ (master inverter output voltage - slave inverter output voltage) ≤ 3V, and the process ends; if so, it means that (master inverter output voltage - slave inverter output voltage) < -3V. According to the above analysis conclusion of the line disconnection condition at the slave end, it is initially determined that a line disconnection fault has occurred at the output end of the slave UPS. To further confirm the accuracy of the result, it is necessary to ensure that there is a certain load on the current machine to exclude the misjudgment caused by the calculation error under no-load conditions. Under the condition of (master inverter output voltage - slave inverter output voltage) < -3V, continue to determine whether the output power of the master is greater than the power threshold. If so, it is determined that a line disconnection fault has occurred at the output end of the slave UPS; if not, clear the current sharing loop integral of the slave UPS and continue to wait for the fault condition to be met and then make a re-judgment.

[0077] In this embodiment, after it is determined in Step 4 that a line disconnection fault has occurred at the output end of the slave UPS, it further includes:

[0078] Disconnect the output of the slave UPS with the line disconnection fault and exit the UPS parallel system, and perform repairs, which does not affect the operation of the master UPS and other slave UPSs without line disconnection faults. After the slave UPS with the line disconnection fault is repaired, it continues to join the UPS parallel system.

[0079] As Figure 7 shown, an embodiment of the present invention further provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the above detection method for open circuit faults in the UPS parallel system.

[0080] As Figure 8As shown, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, the above-described detection method for open-circuit faults in a UPS parallel system is implemented.

[0081] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A detection method for open - circuit faults in a UPS parallel system, where the UPS parallel system needs to provide one UPS main unit, a plurality of UPS slave units and at least one load; characterized in that, The method includes the following steps: Step 1: Each UPS slave unit receives the host inverter output voltage and the host output power sent by the UPS host unit; Step 2: Each UPS slave unit judges the absolute value of the difference between the host inverter output voltage and its own slave inverter output voltage. When the absolute value of the difference is greater than the error threshold, go to Step 3; Step 3: The UPS slave unit judges whether the difference is greater than the error threshold. If not, go to Step 4; if so, continue to judge whether the slave output power is greater than the power threshold. If it is, it is determined that a line disconnection fault has occurred at the output end of the UPS host unit; if not, clear the current-sharing loop integral of this UPS slave unit and continue to wait for the fault condition to be satisfied for re-judgment; Step 4: The UPS slave unit judges whether the difference is less than the negative of the error threshold. If not, end the process; if so, continue to judge whether the host output power is greater than the power threshold. If it is, it is determined that a line disconnection fault has occurred at the output end of this UPS slave unit; if not, clear the current-sharing loop integral of this UPS slave unit and continue to wait for the fault condition to be satisfied for re-judgment.

2. The detection method for open circuit faults applied to the UPS parallel system according to claim 1, wherein In Step 1, the UPS host unit sends the host inverter output voltage and the host output power to each UPS slave unit through the parallel CAN communication bus.

3. The detection method for open circuit faults applied to the UPS parallel system according to claim 1, wherein, Step 2 specifically includes: Step 21: Each UPS slave unit calculates the absolute value of the difference between the host inverter output voltage and its own slave inverter output voltage; Step 22: Compare the absolute value of the difference with the error threshold. If the absolute value of the difference is greater than the error threshold, confirm the comparison result and count the number of times, and go to Step 23; if the absolute value of the difference is not greater than the error threshold, clear the count of the comparison result and end the process; Step 23: Judge whether the number of times counted is greater than or equal to the preset number of times. If so, go to Step 3; if not, repeat Steps 22-23.

4. The detection method for open circuit faults applied to the UPS parallel system according to claim 1, characterized in that, After it is determined in Step 3 that a line disconnection fault has occurred at the output end of the UPS host unit, it also includes: Step 31: The UPS slave unit sets the fault flag variable and sends it to the UPS host unit through the parallel CAN communication bus; Step 32: The UPS slave unit receives the feedback information sent after the UPS host unit receives the set fault flag variable; Step 33: The UPS slave unit stops outputting the fault flag variable to the UPS host unit; Step 34: Disconnect the output of the UPS host unit and exit the UPS parallel system, and select one of the UPS slave units to continue working as the UPS host unit; Step 35: The UPS slave unit receives the set reset variable sent through the parallel CAN communication bus after the line disconnection fault of the UPS host unit is repaired and rejoins the UPS parallel system; Step 36: After the UPS slave unit detects that the reset variable is set, reset the fault flag variable.

5. The detection method for open circuit faults applied to the UPS parallel system according to claim 1, wherein After it is determined in Step 4 that a line disconnection fault has occurred at the output end of the UPS slave unit, it also includes: Disconnect the output of the UPS slave unit with a line disconnection fault and exit the UPS parallel system, and perform repairs, which does not affect the operation of the UPS master unit and other UPS slave units without line disconnection faults. After the UPS slave unit with a line disconnection fault is repaired, continue to join the UPS parallel system.

6. The detection method for open - circuit faults applied to the UPS parallel system according to claim 1, characterized in that, The error threshold is any value in 2v - 10v.

7. The detection method for open - circuit faults applied to the UPS parallel system according to claim 1, characterized in that, The error threshold is 3v.

8. The detection method for open circuit faults applied to the UPS parallel system according to claim 1, wherein, The power threshold is R% of the rated output power of the UPS slave unit, where R is a positive number with 0 < R ≤ 10.

9. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the detection method for open circuit faults applied to the UPS parallel system as described in any one of claims 1 to 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the detection method for open circuit faults applied to the UPS parallel system as described in any one of claims 1 to 8.

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