Ground fault detection method and device for traction converter

Abstract

A traction converter ground fault detection method and device, the method comprising: obtaining the dead time of the traction converter, the ground voltage and the turn-on and turn-off instructions of each power switch device; numbering the bridge arms of each power switch, determining the nth time of the on instruction time, the nth time of the off instruction time and the nth+1 time of the on instruction time of the tube on each bridge arm; n is a positive integer; determining the nth time of the real on time, the nth time of the real off time and the nth+1 time of the real on time, and the corresponding ground voltage; determining the ground voltage change rate during the nth time of the on period and the ground voltage change rate during the nth time of the off period; comparing the preset first ground safety threshold, the second ground safety threshold and the ground voltage change rate during the nth time of the on period and the ground voltage change rate during the nth time of the off period; determining the ground state warning result according to the first comparison result and the second comparison result. The present application improves the fault positioning accuracy and processing efficiency.

Description

Technical Field

[0001] This invention relates to the field of traction converter technology, and more particularly to a method and device for detecting grounding faults in traction converters. Background Technology

[0002] During operation, rail transit locomotives and rolling stock are susceptible to damage to the insulation of traction system electrical components due to factors such as aging electrical cables, vibration and friction, and impacts from foreign objects. In severe cases, this can lead to direct grounding of the traction system's main circuit. Single-point grounding will cause the electrical isolation between the traction transformer's secondary main circuit and the primary circuit of the traction transformer to fail. Two-point or multiple-point grounding will generate a large short-circuit current, causing severe burn-out of the traction system's electrical components. To ensure the safe and reliable operation of the traction system, real-time diagnosis of grounding faults is essential, and timely emergency measures must be taken when grounding anomalies are detected.

[0003] In current high-speed train operations, grounding fault inspections are conducted by designing grounding circuits and collecting grounding voltage data for grounding logic diagnosis. When the grounding voltage exceeds the specified range, auxiliary shutdown, inverter shutdown, and four-quadrant shutdown are performed sequentially to determine the grounding point. This detection method cannot avoid diagnostic errors caused by virtual grounding faults. Furthermore, it can only determine the approximate range of the grounding through logic timing, and cannot pinpoint the exact location. Moreover, the execution of the logic timing requires an action delay, resulting in a relatively slow diagnostic speed. Summary of the Invention

[0004] To address the problems existing in the prior art, the main objective of this invention is to provide a method and device for detecting grounding faults in traction converters, thereby improving fault location accuracy and processing efficiency.

[0005] To achieve the above objectives, embodiments of the present invention provide a method for detecting grounding faults in a traction converter, the method comprising:

[0006] Obtain the dead time, ground voltage, and turn-on / off commands of each power switching device of the traction converter of the monitored EMU.

[0007] The bridge arms of each power switch are numbered, and the nth turn-on command time, nth turn-off command time, and n+1th turn-on command time of each bridge arm upper tube are determined according to the turn-on and turn-off commands of each power switch device of the traction converter; where n is a positive integer.

[0008] Using the dead time and ground voltage of the traction converter, based on the nth turn-on command time, nth turn-off command time and n+1th turn-on command time of each bridge arm upper tube, determine the nth actual turn-on time, nth actual turn-off time and n+1th actual turn-on time of each bridge arm upper tube, as well as the ground voltage corresponding to the nth actual turn-on time, nth actual turn-off time and n+1th actual turn-on time of each bridge arm upper tube respectively;

[0009] Based on the nth actual turn-on time, nth actual turn-off time, n+1th actual turn-on time of each bridge arm upper pipe and the corresponding ground voltage at each time, determine the ground voltage change rate during the nth turn-on period and the ground voltage change rate during the nth turn-off period of each bridge arm upper pipe.

[0010] A first grounding safety threshold is compared with the grounding voltage change rate during the nth turn-on period to obtain a first comparison result, and a second grounding safety threshold is compared with the grounding voltage change rate during the nth turn-off period to obtain a second comparison result.

[0011] Based on the first comparison result and the second comparison result, the grounding status warning result is determined.

[0012] Optionally, in one embodiment of the present invention, determining the grounding state warning result based on the first comparison result and the second comparison result includes:

[0013] If the first comparison result is that the ground voltage change rate during the nth turn-on period is greater than the first ground safety threshold, or the second comparison result is that the ground voltage change rate during the nth turn-off period is greater than the second ground safety threshold, then the grounding status warning result is determined to be that a grounding situation exists.

[0014] Optionally, in one embodiment of the present invention, the method further includes:

[0015] Based on the turn-on and turn-off commands of each power switching device of the traction converter, determine the nth turn-on command time, the nth turn-off command time, and the (n+1)th turn-on command time of each lower tube of the bridge arm.

[0016] Using the dead time and ground voltage of the traction converter, based on the nth turn-on command time, nth turn-off command time and n+1th turn-on command time of each bridge arm lower tube, determine the nth actual turn-on time, nth actual turn-off time and n+1th actual turn-on time of each bridge arm lower tube, as well as the ground voltage corresponding to the nth actual turn-on time, nth actual turn-off time and n+1th actual turn-on time of each bridge arm lower tube.

[0017] Optionally, in one embodiment of the present invention, the method further includes:

[0018] The nth conduction period of each bridge arm's lower pipe is determined based on the nth actual conduction time and the nth actual shutdown time of each lower pipe.

[0019] During the nth conduction period of each bridge arm lower pipe, the duration below the lower limit is determined based on the preset lower limit value of the grounding voltage and the grounding voltage corresponding to the nth actual conduction time and the nth actual turn-off time of each bridge arm lower pipe.

[0020] The proportion of voltage below ground level is determined based on the nth actual turn-on time, the nth actual turn-off time, and the duration below the lower limit value of each bridge arm's lower pipe.

[0021] Optionally, in one embodiment of the present invention, the method further includes:

[0022] The nth conduction period of each bridge arm's upper pipe is determined based on the nth actual conduction time and the nth actual shutdown time of each bridge arm's upper pipe.

[0023] During the nth conduction period of each bridge arm upper pipe, the duration of the voltage exceeding the upper limit is determined based on the preset upper limit value of the ground voltage and the ground voltage corresponding to the nth actual conduction time and the nth actual turn-off time of each bridge arm upper pipe.

[0024] The percentage value above the grounding voltage is determined based on the nth actual turn-on time, the nth actual turn-off time, and the duration above the upper limit value of each bridge arm pipe.

[0025] Optionally, in one embodiment of the present invention, the method further includes:

[0026] Based on the first comparison result, the second comparison result, the proportion of voltage below ground voltage, and the proportion of voltage above ground voltage, the DC bus grounding warning result is determined.

[0027] This invention also provides a traction converter grounding fault detection device, the device comprising:

[0028] The data acquisition module is used to acquire the dead time, ground voltage, and turn-on / off commands of the traction converter of the monitored EMU.

[0029] The turn-on command module is used to number the bridge arms of each power switch and determine the nth turn-on command time, the nth turn-off command time, and the (n+1)th turn-on command time of each bridge arm's upper tube according to the turn-on and turn-off commands of each power switch device of the traction converter; where n is a positive integer.

[0030] The grounding voltage module is used to determine the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm upper tube based on the dead time and grounding voltage of the traction converter, according to the nth turn-on command time, nth turn-off command time, and n+1th turn-on command time of each bridge arm upper tube. It also determines the grounding voltage corresponding to the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm upper tube.

[0031] The voltage change rate module is used to determine the ground voltage change rate during the nth turn-on period and the ground voltage change rate during the nth turn-off period of each bridge arm upper tube based on the nth actual turn-on time, the nth actual turn-off time, the n+1th actual turn-on time of each bridge arm upper tube and the ground voltage corresponding to each time.

[0032] The comparison result module is used to compare the preset first ground safety threshold with the ground voltage change rate during the nth conduction period to obtain a first comparison result, and to compare the preset second ground safety threshold with the ground voltage change rate during the nth turn-off period to obtain a second comparison result;

[0033] The grounding early warning module is used to determine the grounding status early warning result based on the first comparison result and the second comparison result.

[0034] Optionally, in one embodiment of the present invention, the grounding warning module is further configured to determine that there is a grounding situation if the first comparison result is that the grounding voltage change rate during the nth turn-on period is greater than the first grounding safety threshold, or the second comparison result is that the grounding voltage change rate during the nth turn-off period is greater than the second grounding safety threshold.

[0035] Optionally, in one embodiment of the present invention, the apparatus further includes:

[0036] The tube-down timing module is used to determine the nth turn-on command time, the nth turn-off command time, and the n+1th turn-on command time for each bridge arm tube-down based on the turn-on and turn-off commands of each power switching device of the traction converter.

[0037] The lower tube voltage module is used to determine the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm lower tube based on the dead time and ground voltage of the traction converter, according to the nth turn-on command time, nth turn-off command time, and n+1th turn-on command time of each bridge arm lower tube, as well as the ground voltage corresponding to the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm lower tube.

[0038] Optionally, in one embodiment of the present invention, the apparatus further includes:

[0039] The lower pipe conduction period module is used to determine the nth conduction period of each bridge arm lower pipe based on the nth actual conduction time and the nth actual shutdown time of each bridge arm lower pipe.

[0040] The lower limit module is used to determine the duration of the voltage below the lower limit during the nth conduction period of each bridge arm lower pipe, based on the preset lower limit of the ground voltage and the ground voltage corresponding to the nth actual conduction time and the nth actual turn-off time of each bridge arm lower pipe.

[0041] The first proportional value module is used to determine the proportional value below the grounding voltage based on the nth actual turn-on time, the nth actual turn-off time, and the duration below the lower limit value of each bridge arm's lower pipe.

[0042] Optionally, in one embodiment of the present invention, the apparatus further includes:

[0043] The upper pipe conduction period module is used to determine the nth conduction period of each bridge arm upper pipe based on the nth actual conduction time and the nth actual shutdown time of each bridge arm upper pipe.

[0044] The upper limit module is used to determine the duration of the voltage exceeding the upper limit during the nth conduction period of each bridge arm pipe, based on the preset upper limit of the ground voltage and the ground voltage corresponding to the nth actual conduction time and the nth actual turn-off time of each bridge arm pipe.

[0045] The second proportional value module is used to determine the proportional value above the grounding voltage based on the nth actual turn-on time, the nth actual turn-off time, and the duration above the upper limit value of each bridge arm pipe.

[0046] Optionally, in one embodiment of the present invention, the apparatus further includes:

[0047] The DC bus early warning module is used to determine the DC bus grounding early warning result based on the first comparison result, the second comparison result, the lower grounding voltage ratio value, and the higher grounding voltage ratio value.

[0048] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-described method.

[0049] The present invention also provides a computer-readable storage medium storing a computer program that performs the above-described methods by a computer.

[0050] The present invention also provides a computer program product, including a computer program / instructions, which, when executed by a processor, implement the steps of the above-described method.

[0051] This invention monitors the grounding status of the traction converter by directly extracting the grounding voltage and the switching status of each power device. No additional hardware is required. It makes full use of the existing structure and diagnostic circuit of the traction converter. While accurately determining the occurrence of grounding faults, it can quickly locate the location of the grounding fault, eliminating the complicated manual troubleshooting process, improving fault handling efficiency, and avoiding damage to the normal operation of the system caused by grounding faults, thus improving the safety of the system. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a flowchart of a traction converter grounding fault detection method according to an embodiment of the present invention;

[0054] Figure 2 This is a flowchart for determining the grounding voltage of the lower tube of the bridge arm in an embodiment of the present invention;

[0055] Figure 3 This is a flowchart illustrating the determination of a percentage value below the grounding voltage in an embodiment of the present invention;

[0056] Figure 4 This is a flowchart illustrating the determination of a percentage value higher than the grounding voltage in an embodiment of the present invention;

[0057] Figure 5A and Figure 5B This is a schematic diagram of the converter structure and PHM board in an embodiment of the present invention;

[0058] Figure 6 This is a schematic diagram of the turn-on / turn-off command and ground voltage acquisition of the upper tube of the i-th bridge arm in an embodiment of the present invention;

[0059] Figure 7 This is a schematic diagram of PHM data acquisition and processing in the grounding condition of the EMU inverter side in an embodiment of the present invention;

[0060] Figure 8 This is a schematic diagram of the structure of a traction converter grounding fault detection device according to an embodiment of the present invention;

[0061] Figure 9 This is a schematic diagram of the structure of a traction converter grounding fault detection device in another embodiment of the present invention;

[0062] Figure 10This is a schematic diagram of the structure of the traction converter grounding fault detection device in another embodiment of the present invention;

[0063] Figure 11 This is a schematic diagram of the structure of a traction converter grounding fault detection device in another embodiment of the present invention;

[0064] Figure 12 This is a schematic diagram of the structure of a traction converter grounding fault detection device in a specific embodiment of the present invention;

[0065] Figure 13 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0066] This invention provides a method and apparatus for detecting grounding faults in traction converters.

[0067] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0068] like Figure 1 The diagram shows a flowchart of a traction converter grounding fault detection method according to an embodiment of the present invention. The execution subject of the traction converter grounding fault detection method provided in this embodiment includes, but is not limited to, a computer. This invention monitors the grounding status of the converter by directly extracting the grounding voltage of the traction converter and the switching status of each power device. No additional hardware is required, fully utilizing the existing structure and diagnostic circuitry of the traction converter. While accurately determining the occurrence of a grounding fault, it can quickly locate the fault location, eliminating the need for complex manual troubleshooting, improving fault handling efficiency, and avoiding damage to the system's abnormal operation caused by grounding faults, thus improving system safety. The method shown in the diagram:

[0069] Step S1: Obtain the dead time, ground voltage, and turn-on / off commands of each power switching device of the traction converter of the monitored EMU.

[0070] Step S2: Number the bridge arms of each power switch, and determine the nth turn-on command time, nth turn-off command time and n+1th turn-on command time of each bridge arm's upper tube according to the turn-on and turn-off commands of each power switch device of the traction converter; where n is a positive integer.

[0071] Step S3: Using the dead time and ground voltage of the traction converter, determine the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm upper tube according to the nth turn-on command time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm upper tube, as well as the ground voltage corresponding to the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm upper tube respectively.

[0072] Step S4: Based on the nth actual turn-on time, the nth actual turn-off time, the (n+1)th actual turn-on time of each bridge arm upper pipe and the ground voltage corresponding to each time, determine the ground voltage change rate during the nth turn-on period and the ground voltage change rate during the nth turn-off period of each bridge arm upper pipe.

[0073] Step S5: Compare the preset first grounding safety threshold with the grounding voltage change rate during the nth turn-on period to obtain a first comparison result; and compare the preset second grounding safety threshold with the grounding voltage change rate during the nth turn-off period to obtain a second comparison result.

[0074] Step S6: Determine the grounding status warning result based on the first comparison result and the second comparison result.

[0075] This includes collecting the ground voltage, intermediate voltage, turn-on and turn-off commands of each power switching device, and dead time of the traction converter of the monitored EMU motor. Specifically, the data acquisition method can use conventional methods, which will not be elaborated further here.

[0076] Furthermore, the power switches of the traction converter are numbered from 1 to n according to the bridge arms. Based on the turn-on and turn-off commands of the two switches in the i-th (i = 1, 2, ..., n) bridge arm, the time T of the nth turn-on command of the upper switch in the i-th bridge arm is determined. iu-non The time T of the nth shutdown instruction iu-noff The time T of the (n+1)th turn-on command iu-(n+1)on Determine the time T of the nth conduction command for the i-th lower pipe of the bridge arm. id-non Shutdown instruction time T id-noff The time T of the (n+1)th turn-on command id-(n+1)on Among them, T iu-noff The subscript i represents the i-th bridge arm, u / d represent the upper tube and the lower tube respectively, n represents the n-th turn-on and turn-off, and on / off represent turn-on and turn-off.

[0077] Furthermore, consider the dead time T. dead Based on the above times, determine the nth actual conduction time T of the upper pipe of the i-th bridge arm. iu-non +T dead and the grounding voltage U at that moment iue-nonThe nth real shutdown time T iu-noff +T dead and the grounding voltage U at that moment iue-noff The (n+1)th actual conduction time T iu-(n+1)on +T dead and the grounding voltage U at that moment iue-(n+1)on Determine the actual conduction time T of the lower pipe of the i-th bridge arm for the nth time. id-non +T dead and the grounding voltage U at that moment ide-non The nth real shutdown time T id-noff +T dead and the grounding voltage U at that moment ide-noff The (n+1)th actual conduction time T id-(n+1)on +T dead and the grounding voltage U at that moment ide-(n+1)on .

[0078] Furthermore, based on the above times and corresponding grounding voltages, the nth conduction period of the upper tube of the i-th bridge arm (T) is obtained. iu-non +T dead ~T iu-noff +T dead The absolute value of the grounding voltage change ΔU ie-non =|U iue-noff -U iue-non |, during the nth shutdown period (T) iu-noff +T dead ~T iu-(n+1)on +T dead The absolute value of the grounding voltage change ΔU ie-noff =|U iue - (n+1)on -U iue-noff | and calculate the ground voltage change rate A during the nth conduction period of the upper pipe of the i-th bridge arm. in =ΔU ie-non / (T iu-noff -T iu-non The rate of change of ground voltage B during the nth turn-off of the upper pipe of the i-th bridge arm in =ΔU ie-noff / (T iu-(n+1)on -T iu-noff ).

[0079] Furthermore, considering the dead time, using the above time points and corresponding grounding voltages, the period of the nth conduction of the upper tube of the i-th bridge arm (T) is determined. iu-non +T dead ~T iu-noff +T dead The grounding voltage and its corresponding grounding voltage are higher than the upper limit of the normal grounding voltage range, U. up-limit Duration ΔT iu-nonRecord the value C, which is higher than the grounding voltage. in =ΔT iu-non / (T iu-noff -T iu - non ); where U up-limit The intermediate voltage U can be selected according to the actual engineering application. dc 80%.

[0080] Furthermore, considering the dead time, using the above time points and corresponding grounding voltages, the nth conduction period (T) of the lower tube of the i-th bridge arm is determined. id-non +T dead ~T id-noff +T dead The grounding voltage and its corresponding grounding voltage are lower than the lower limit of the normal grounding voltage range, U. low-limit Duration ΔT id-non Record the value D, which is lower than the grounding voltage. in =ΔT id-non / (T id-noff -T id - non ); where U up-limit The intermediate voltage U can be selected according to the actual engineering application. dc 20%.

[0081] As an embodiment of the present invention, determining the grounding state warning result based on the first comparison result and the second comparison result includes: if the first comparison result is that the grounding voltage change rate during the nth conduction period is greater than the first grounding safety threshold, or the second comparison result is that the grounding voltage change rate during the nth turn-off period is greater than the second grounding safety threshold, then the grounding state warning result is determined to be that a grounding situation exists.

[0082] The ground fault characterization value A of the i-th power device bridge arm is obtained based on the above calculation. in B in C in D in The value, and the grounding safety limit value, i.e., the first grounding safety threshold. A Second grounding safety threshold B Third grounding safety threshold C Fourth grounding safety threshold D To make comparisons.

[0083] Specifically, based on the first comparison result and the second comparison result, the grounding state early warning result is obtained, that is, when A in > A Or B in > B The system can determine if there is a grounding issue on the AC side of the bridge arm and issue a grounding status warning.

[0084] Furthermore, when there are at least two bridge arms (i, m...)A in < A And B in < B A mn < A And B mn < B C in > C C mn > C It can promptly determine if there is a grounding situation on the high-voltage side of the DC bus and issue a grounding status warning.

[0085] Furthermore, when there are at least two bridge arms (i, m...)A in < A And B in < B A mn < A And B mn < B D in < D D mn < D It can promptly determine if there is a grounding situation on the low-voltage side of the DC bus and issue a grounding status warning.

[0086] As one embodiment of the present invention, such as Figure 2 As shown, the method also includes:

[0087] Step S21: Based on the turn-on and turn-off commands of each power switching device of the traction converter, determine the nth turn-on command time, the nth turn-off command time, and the (n+1)th turn-on command time of each lower tube of the bridge arm.

[0088] Step S22: Using the dead time and ground voltage of the traction converter, determine the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm lower tube according to the nth turn-on command time, nth turn-off command time, and n+1th turn-on command time of each bridge arm lower tube, as well as the ground voltage corresponding to the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm lower tube.

[0089] Specifically, the power switches of the traction converter are numbered from 1 to n according to the bridge arms. Based on the turn-on and turn-off commands of the two switches of the i-th (i = 1, 2, ..., n) bridge arm, the time T of the nth turn-on command of the lower switch of the i-th bridge arm is determined. id-non Shutdown instruction time T id-noff The time T of the (n+1)th turn-on command id-(n+1)on .

[0090] Furthermore, consider the dead time T. dead Based on the above times, determine the nth actual conduction time T of the lower pipe of the i-th bridge arm. id-non +T dead and the grounding voltage U at that moment ide-non The nth real shutdown time T id-noff +T dead and the grounding voltage U at that moment ide-noff The (n+1)th actual conduction time T id-(n+1)on +T dead and the grounding voltage U at that moment ide-(n+1)on .

[0091] In this embodiment, as Figure 3 As shown, the method also includes:

[0092] Step S31: Determine the nth conduction period of each bridge arm's lower pipe based on the nth actual conduction time and the nth actual shutdown time of each lower pipe.

[0093] Step S32: During the nth conduction period of each bridge arm lower pipe, determine the duration below the lower limit value based on the preset lower limit value of the grounding voltage and the grounding voltage corresponding to the nth actual conduction time and the nth actual turn-off time of each bridge arm lower pipe.

[0094] Step S33: Determine the percentage value below the grounding voltage based on the nth actual turn-on time, the nth actual turn-off time, and the duration below the lower limit value for each bridge arm lower pipe.

[0095] Among these considerations, the dead time is used to determine the nth conduction period (T) of the lower tube of the i-th bridge arm using the aforementioned time points and corresponding grounding voltages. id-non +T dead ~T id-noff +T dead ), and the grounding voltage during the conduction period is lower than the lower limit of the normal grounding voltage range (lower limit of grounding voltage) U. low - limit Duration ΔT id-non (Lower limit duration), recorded as the proportion D below the grounding voltage. in =ΔT id-non / (T id-noff -T id-non ); where U up-limit The intermediate voltage U can be selected based on the actual engineering application. dc 20%.

[0096] In this embodiment, as Figure 4 As shown, the method also includes:

[0097] Step S41: Determine the nth conduction period of each bridge arm's upper pipe based on the nth actual conduction time and the nth actual turn-off time of each upper pipe.

[0098] Step S42: During the nth conduction period of each bridge arm upper pipe, determine the duration of the voltage exceeding the upper limit based on the preset upper limit value of the grounding voltage and the grounding voltage corresponding to the nth actual conduction time and the nth actual turn-off time of each bridge arm upper pipe.

[0099] Step S43: Determine the percentage value above the grounding voltage based on the nth actual turn-on time, the nth actual turn-off time, and the duration above the upper limit value of each bridge arm pipe.

[0100] Among these considerations, the dead time is used to determine the nth conduction period (T) of the upper pipe of the i-th bridge arm using the aforementioned time and corresponding grounding voltage. iu-non +T dead ~T iu-noff +T dead The grounding voltage and its corresponding grounding voltage are higher than the upper limit of the normal grounding voltage range (i.e., the upper limit of the grounding voltage). up-limit Duration ΔT iu-non (Duration above the upper limit), recorded as the percentage C above the ground voltage. in =ΔT iu-non / (T iu-noff -T iu-non ); where U up-limit The intermediate voltage U can be selected based on the actual engineering application. dc 80%.

[0101] In this embodiment, the method further includes: determining the DC bus grounding warning result based on the first comparison result, the second comparison result, the lower grounding voltage ratio value, and the higher grounding voltage ratio value.

[0102] The ground fault characterization value A of the i-th power device bridge arm is obtained based on the above calculation. in B in C in D in The value, and the grounding safety limit value, i.e., the first grounding safety threshold. A Second grounding safety threshold B Third grounding safety threshold C Fourth grounding safety threshold D To make comparisons.

[0103] Specifically, based on the first comparison result and the second comparison result, the grounding state early warning result is obtained, that is, when A in > A Or B in > BThe system can determine if there is a grounding issue on the AC side of the bridge arm and issue a grounding status warning.

[0104] Furthermore, when there are at least two bridge arms (i, m...)A in < A And B in < B A mn < A And B mn < B C in > C C mn > C The system can determine if there is a grounding situation on the high-voltage side of the DC bus (i.e., DC bus grounding warning result) and issue a grounding status warning.

[0105] Furthermore, when there are at least two bridge arms (i, m...)A in < A And B in < B A mn < A And B mn < B D in < D D mn < D The system can determine if there is a grounding situation on the low-voltage side of the DC bus (i.e., DC bus grounding early warning result) and issue a grounding status warning.

[0106] This invention directly extracts the grounding voltage of the traction converter and the switching status of each power device to monitor the grounding status of the converter. No additional hardware facilities are required. It makes full use of the existing structure and diagnostic circuit of the traction converter. While accurately determining the occurrence of grounding faults, this invention can quickly locate the bridge arm or bus where the grounding fault occurs, eliminating the complicated manual troubleshooting process, improving fault handling efficiency, and avoiding damage to the normal operation of the system caused by grounding faults, thus improving the safety of the system.

[0107] In one specific embodiment of this invention, due to the neglect of the acquisition accuracy of the traction converter ground voltage, researchers have not clearly analyzed the actual waveform and the underlying mechanism of the ground voltage changes. With the promotion of PHM (Prognostics and Health Management) technology, high-precision data samples more intuitively reflect the ground voltage change law based on the characteristics of the converter itself. This invention provides a ground fault detection method for traction converters based on a comprehensive judgment of ground voltage and the operating timing of switching devices, such as... Figure 5A and Figure 5B As shown, the method includes:

[0108] Collect the ground voltage U of the traction converter of the monitored EMU motor. e Intermediate voltage U dc , and turn-on / off commands for each power switching device.

[0109] The power switches of the traction converter are numbered from 1 to n according to the bridge arms. Based on the turn-on and turn-off commands of the two switches in the i-th (i = 1, 2, ..., n) bridge arm, the time T of the nth turn-on command of the upper switch in the i-th bridge arm is determined. iu-non The time T of the nth shutdown instruction iu-noff The time T of the (n+1)th turn-on command iu - (n+1)on Determine the time T of the nth conduction command for the i-th lower pipe of the bridge arm. id-non Shutdown instruction time T id-noff The time T of the (n+1)th turn-on command id-(n+1)on Among them, T iu-noff The subscript i represents the i-th bridge arm, u / d represent the upper tube and the lower tube respectively, n represents the n-th turn-on and turn-off, and on / off represent turn-on and turn-off.

[0110] Considering dead time T dead Determine the actual conduction time T of the upper pipe of the i-th bridge arm for the nth time. iu-non +T dead and the grounding voltage U at that moment iue-non The nth real shutdown time T iu-noff +T dead and the grounding voltage U at that moment iue-noff The (n+1)th actual conduction time T iu-(n+1)on +T dead and the grounding voltage U at that moment iue-(n+1)on Determine the actual conduction time T of the lower pipe of the i-th bridge arm for the nth time. id-non +T dead and the grounding voltage U at that moment ide-non The nth real shutdown time T id-noff +T dead and the grounding voltage U at that moment ide-noff The (n+1)th actual conduction time T id-(n+1)on +T dead and the grounding voltage U at that moment ide-(n+1)on See the detailed sampling diagram below. Figure 6 .

[0111] Determine the period of the nth conduction of the upper pipe of the i-th bridge arm (T) iu-non +T dead ~T iu-noff +T dead The absolute value of the grounding voltage change ΔUie-non =|U iue-noff -U iue-non |, during the nth shutdown period (T) iu-noff +T dead ~T iu-(n+1)on +T dead The absolute value of the grounding voltage change ΔU ie-noff =|U iue-(n+1)on -U iue-noff | and calculate the ground voltage change rate A during the nth conduction period of the upper pipe of the i-th bridge arm. in =ΔU ie-non / (T iu-noff -T iu-non The rate of change of ground voltage B during the nth turn-off of the upper pipe of the i-th bridge arm in =ΔU ie-noff / (T iu-(n+1)on -T iu-noff ).

[0112] Considering the dead time, record the period (T) during the nth conduction of the upper pipe of the i-th bridge arm. iu-non +T dead ~T iu-noff +T dead The grounding voltage is higher than the upper limit of the normal grounding voltage range, U. up-limit Duration ΔT iu-non Record the value C, which is higher than the grounding voltage. in =ΔT iu-non / (T iu-noff -T iu-non ); where U up-limit The intermediate voltage U can be selected according to the actual engineering application. dc 80%.

[0113] Considering the dead time, determine the nth conduction period (T) of the lower pipe of the i-th bridge arm. id-non +T dead ~T id-noff +T dead The grounding voltage is lower than the lower limit of the normal grounding voltage range, U. low-limit Duration ΔT id-non Record the value D, which is lower than the grounding voltage. in =ΔT id-non / (T id-noff -T id-non ); where U up-limit The intermediate voltage U can be selected according to the actual engineering application. dc 20%.

[0114] Based on the above calculations, the ground fault characterization value A of the i-th power device bridge arm is obtained. in B in Cin D in Value, and grounding safety limit value A , B , C , D When comparing, when A in > A Or B in > B The system can determine if there is a grounding issue on the AC side of the bridge arm and issue a grounding status warning.

[0115] When there are at least two bridge arms (i, m...)A in < A And B in < B A mn < A And B mn < B C in > C C mn > C It can promptly determine if there is a grounding situation on the high-voltage side of the DC bus and issue a grounding status warning.

[0116] When there are at least two bridge arms (i, m...)A in < A And B in < B A mn < A And B mn < B D in < D D mn < D It can promptly determine if there is a grounding situation on the low-voltage side of the DC bus and issue a grounding status warning.

[0117] Figure 7 This shows the switching status and grounding voltage waveforms when the AC side of the 5th bridge arm on the inverter output side is grounded. When the AC side of the 5th bridge arm is grounded, A... 5n > A With B 5n > B The simultaneous fulfillment of these conditions proves the feasibility of this invention.

[0118] This invention monitors the grounding status of the traction converter by directly extracting the grounding voltage and the switching status of each power device. No additional hardware is required. It makes full use of the existing structure and diagnostic circuit of the traction converter. While accurately determining the occurrence of grounding faults, it can quickly locate the location of the grounding fault, eliminating the complicated manual troubleshooting process, improving fault handling efficiency, and avoiding damage to the normal operation of the system caused by grounding faults, thus improving the safety of the system.

[0119] like Figure 8 The figure shows a schematic diagram of a traction converter grounding fault detection device according to an embodiment of the present invention. The device shown in the figure includes:

[0120] The data acquisition module 10 is used to acquire the dead time, ground voltage, and turn-on and turn-off commands of the traction converter of the monitored EMU.

[0121] The turn-on command module 20 is used to number the bridge arms of each power switch and determine the nth turn-on command time, the nth turn-off command time and the (n+1)th turn-on command time of each bridge arm's upper tube according to the turn-on and turn-off commands of each power switch device of the traction converter; where n is a positive integer.

[0122] The grounding voltage module 30 is used to determine the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm upper pipe based on the dead time and grounding voltage of the traction converter, according to the nth turn-on command time, nth turn-off command time, and n+1th turn-on command time of each bridge arm upper pipe, as well as the grounding voltage corresponding to the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm upper pipe respectively.

[0123] The voltage change rate module 40 is used to determine the ground voltage change rate during the nth turn-on period and the ground voltage change rate during the nth turn-off period of each bridge arm upper tube based on the nth actual turn-on time, the nth actual turn-off time, the n+1th actual turn-on time and the ground voltage corresponding to each time.

[0124] The comparison result module 50 is used to compare the preset first ground safety threshold with the ground voltage change rate during the nth turn-on period to obtain a first comparison result, and to compare the preset second ground safety threshold with the ground voltage change rate during the nth turn-off period to obtain a second comparison result;

[0125] The grounding early warning module 60 is used to determine the grounding status early warning result based on the first comparison result and the second comparison result.

[0126] As an embodiment of the present invention, the grounding warning module is further configured to determine that there is a grounding situation if the first comparison result is that the grounding voltage change rate during the nth turn-on period is greater than the first grounding safety threshold, or the second comparison result is that the grounding voltage change rate during the nth turn-off period is greater than the second grounding safety threshold.

[0127] As one embodiment of the present invention, such as Figure 9 As shown, the device also includes:

[0128] The tube-down timing module 71 is used to determine the nth turn-on command time, the nth turn-off command time and the (n+1)th turn-on command time of each bridge arm tube-down according to the turn-on and turn-off commands of each power switching device of the traction converter.

[0129] The lower tube voltage module 72 is used to determine the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm lower tube based on the dead time and ground voltage of the traction converter, according to the nth turn-on command time, nth turn-off command time, and n+1th turn-on command time of each bridge arm lower tube, as well as the ground voltage corresponding to the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm lower tube.

[0130] In this embodiment, as Figure 10 As shown, the device also includes:

[0131] The lower pipe conduction period module 81 is used to determine the nth conduction period of each lower pipe based on the nth actual conduction time and the nth actual shutdown time of each lower pipe of each bridge arm.

[0132] The lower limit module 82 is used to determine the duration of the voltage below the lower limit during the nth conduction period of each bridge arm lower pipe, based on the preset lower limit of the ground voltage and the ground voltage corresponding to the nth actual conduction time and the nth actual turn-off time of each bridge arm lower pipe respectively.

[0133] The first proportional value module 83 is used to determine the proportional value below the grounding voltage based on the nth actual turn-on time, the nth actual turn-off time, and the duration below the lower limit value of each bridge arm lower pipe.

[0134] In this embodiment, as Figure 11 As shown, the device also includes:

[0135] The upper pipe conduction period module 91 is used to determine the nth conduction period of each bridge arm upper pipe based on the nth actual conduction time and the nth actual shutdown time of each bridge arm upper pipe.

[0136] The upper limit module 92 is used to determine the duration of the voltage exceeding the upper limit during the nth conduction period of each bridge arm pipe, based on the preset upper limit of the ground voltage and the ground voltage corresponding to the nth actual conduction time and the nth actual turn-off time of each bridge arm pipe respectively.

[0137] The second proportional value module 93 is used to determine the proportional value above the grounding voltage based on the nth actual turn-on time, the nth actual turn-off time, and the duration above the upper limit value of each bridge arm pipe.

[0138] In this embodiment, as Figure 12 As shown, the device also includes:

[0139] The DC bus early warning module 101 is used to determine the DC bus grounding early warning result based on the first comparison result, the second comparison result, the lower grounding voltage ratio value, and the higher grounding voltage ratio value.

[0140] Based on the same concept as the aforementioned traction converter grounding fault detection method, this invention also provides a traction converter grounding fault detection device. Since the principle by which this traction converter grounding fault detection device solves the problem is similar to that of the traction converter grounding fault detection method, the implementation of this traction converter grounding fault detection device can refer to the implementation of the traction converter grounding fault detection method; repeated details will not be elaborated further.

[0141] This invention monitors the grounding status of the traction converter by directly extracting the grounding voltage and the switching status of each power device. No additional hardware is required. It makes full use of the existing structure and diagnostic circuit of the traction converter. While accurately determining the occurrence of grounding faults, it can quickly locate the location of the grounding fault, eliminating the complicated manual troubleshooting process, improving fault handling efficiency, and avoiding damage to the normal operation of the system caused by grounding faults, thus improving the safety of the system.

[0142] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-described method.

[0143] The present invention also provides a computer program product, including a computer program / instructions, which, when executed by a processor, implement the steps of the above-described method.

[0144] The present invention also provides a computer-readable storage medium storing a computer program that performs the above-described methods by a computer.

[0145] like Figure 13As shown, the electronic device 600 may also include: a communication module 110, an input unit 120, an audio processor 130, a display 160, and a power supply 170. It is worth noting that the electronic device 600 does not necessarily need to include these components. Figure 13 All components shown; in addition, the electronic device 600 may also include Figure 13 For components not shown, please refer to existing technologies.

[0146] like Figure 13 As shown, the central processing unit 100, sometimes also referred to as a controller or operating control, may include a microprocessor or other processor device and / or logic device. The central processing unit 100 receives inputs and controls the operation of various components of the electronic device 600.

[0147] The memory 140 may be, for example, one or more of a cache, flash memory, hard drive, removable media, volatile memory, non-volatile memory, or other suitable devices. It may store the aforementioned failure-related information, and also store a program for executing that information. The central processing unit 100 may execute the program stored in the memory 140 to perform information storage or processing, etc.

[0148] Input unit 120 provides input to central processing unit 100. Input unit 120 may be, for example, a keypad or touch input device. Power supply 170 provides power to electronic device 600. Display 160 displays images and text. Display may be, for example, an LCD display, but is not limited thereto.

[0149] The memory 140 can be a solid-state memory, such as a read-only memory (ROM), random access memory (RAM), a SIM card, etc. It can also be a memory that retains information even when power is off, can be selectively erased, and contains more data; examples of this type of memory are sometimes referred to as EPROMs. The memory 140 can also be some other type of device. The memory 140 includes a buffer memory 141 (sometimes referred to as a buffer). The memory 140 may include an application / function storage unit 142 for storing application programs and function programs or processes for executing the operation of the electronic device 600 via the central processing unit 100.

[0150] The memory 140 may also include a data storage unit 143 for storing data, such as contacts, digital data, pictures, sounds, and / or any other data used by the electronic device. The driver storage unit 144 of the memory 140 may include various drivers for the electronic device's communication functions and / or for performing other functions of the electronic device (such as messaging applications, address book applications, etc.).

[0151] The communication module 110 is a transmitter / receiver 110 that transmits and receives signals via antenna 111. The communication module (transmitter / receiver) 110 is coupled to the central processing unit 100 to provide input signals and receive output signals, which can be the same as in a conventional mobile communication terminal.

[0152] Based on different communication technologies, multiple communication modules 110 can be configured in the same electronic device, such as cellular network modules, Bluetooth modules, and / or wireless LAN modules. The communication module (transmitter / receiver) 110 is also coupled to a speaker 131 and a microphone 132 via an audio processor 130 to provide audio output via the speaker 131 and receive audio input from the microphone 132, thereby enabling typical telecommunications functions. The audio processor 130 may include any suitable buffer, decoder, amplifier, etc. Additionally, the audio processor 130 is coupled to a central processing unit 100, enabling on-device recording via the microphone 132 and on-device playback of stored audio via the speaker 131.

[0153] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0154] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0155] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0156] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0157] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for detecting grounding faults in a traction converter, characterized in that, The method includes: Obtain the dead time, ground voltage, and turn-on / off commands of each power switching device of the traction converter of the monitored EMU. Each power switch arm is numbered, and the nth turn-on command time, nth turn-off command time, and n+1th turn-on command time of each power switch device in the traction converter are determined according to the turn-on and turn-off commands of each power switch device; where n is a positive integer. Using the dead time and ground voltage of the traction converter, based on the nth turn-on command time, nth turn-off command time and n+1th turn-on command time of each bridge arm upper tube, determine the nth actual turn-on time, nth actual turn-off time and n+1th actual turn-on time of each bridge arm upper tube, as well as the ground voltage corresponding to the nth actual turn-on time, nth actual turn-off time and n+1th actual turn-on time of each bridge arm upper tube respectively; Based on the nth actual turn-on time, the nth actual turn-off time, the n+1th actual turn-on time of each bridge arm upper pipe and the ground voltage corresponding to each time, determine the ground voltage change rate during the nth turn-on period and the ground voltage change rate during the nth turn-off period of each bridge arm upper pipe. A first grounding safety threshold is compared with the grounding voltage change rate during the nth turn-on period to obtain a first comparison result, and a second grounding safety threshold is compared with the grounding voltage change rate during the nth turn-off period to obtain a second comparison result. Based on the first comparison result and the second comparison result, the grounding status warning result is determined.

2. The method according to claim 1, characterized in that, Based on the first comparison result and the second comparison result, the grounding status warning result is determined as follows: If the first comparison result is that the ground voltage change rate during the nth turn-on period is greater than the first ground safety threshold, or the second comparison result is that the ground voltage change rate during the nth turn-off period is greater than the second ground safety threshold, then the grounding status warning result is determined to be that a grounding situation exists.

3. The method according to claim 1, characterized in that, The method further includes: Based on the turn-on and turn-off commands of each power switching device of the traction converter, determine the nth turn-on command time, the nth turn-off command time, and the (n+1)th turn-on command time of each lower tube of the bridge arm. Using the dead time and ground voltage of the traction converter, based on the nth turn-on command time, nth turn-off command time and n+1th turn-on command time of each bridge arm lower tube, determine the nth actual turn-on time, nth actual turn-off time and n+1th actual turn-on time of each bridge arm lower tube, as well as the ground voltage corresponding to the nth actual turn-on time, nth actual turn-off time and n+1th actual turn-on time of each bridge arm lower tube.

4. The method according to claim 3, characterized in that, The method further includes: The nth conduction period of each bridge arm's lower pipe is determined based on the nth actual conduction time and the nth actual shutdown time of each lower pipe. During the nth conduction period of each bridge arm lower pipe, the duration below the lower limit is determined based on the preset lower limit value of the grounding voltage and the grounding voltage corresponding to the nth actual conduction time and the nth actual turn-off time of each bridge arm lower pipe. The proportion of voltage below ground level is determined based on the nth actual turn-on time, the nth actual turn-off time, and the duration below the lower limit value of each bridge arm lower pipe.

5. The method according to claim 4, characterized in that, The method further includes: The nth conduction period of each bridge arm's upper pipe is determined based on the nth actual conduction time and the nth actual shutdown time of each bridge arm's upper pipe. During the nth conduction period of each bridge arm upper pipe, the duration of the voltage exceeding the upper limit is determined based on the preset upper limit value of the ground voltage and the ground voltage corresponding to the nth actual conduction time and the nth actual turn-off time of each bridge arm upper pipe. The ratio of voltage above ground voltage is determined based on the nth actual turn-on time, the nth actual turn-off time, and the duration above the upper limit value of each bridge arm pipe.

6. The method according to claim 5, characterized in that, The method further includes: Based on the first comparison result, the second comparison result, the proportion of voltage below ground voltage, and the proportion of voltage above ground voltage, the DC bus grounding warning result is determined.

7. A traction converter grounding fault detection device, characterized in that, The device includes: The data acquisition module is used to acquire the dead time, ground voltage, and turn-on / off commands of the traction converter of the monitored EMU. The turn-on command module is used to number the bridge arms of each power switch and determine the nth turn-on command time, the nth turn-off command time, and the (n+1)th turn-on command time of each bridge arm's upper tube according to the turn-on and turn-off commands of each power switch device of the traction converter; where n is a positive integer. The grounding voltage module is used to determine the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm upper tube based on the dead time and grounding voltage of the traction converter, according to the nth turn-on command time, nth turn-off command time, and n+1th turn-on command time of each bridge arm upper tube, as well as the grounding voltage corresponding to the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm upper tube respectively. The voltage change rate module is used to determine the ground voltage change rate during the nth turn-on period and the ground voltage change rate during the nth turn-off period of each bridge arm upper tube based on the nth actual turn-on time, the nth actual turn-off time, the n+1th actual turn-on time and the ground voltage corresponding to each time. The comparison result module is used to compare a preset first grounding safety threshold with the grounding voltage change rate during the nth turn-on period to obtain a first comparison result, and to compare a preset second grounding safety threshold with the grounding voltage change rate during the nth turn-off period to obtain a second comparison result; The grounding early warning module is used to determine the grounding status early warning result based on the first comparison result and the second comparison result.

8. The apparatus according to claim 7, characterized in that, The grounding early warning module is further configured to determine that the grounding status early warning result indicates the presence of a grounding condition if the first comparison result is that the grounding voltage change rate during the nth turn-on period is greater than the first grounding safety threshold, or the second comparison result is that the grounding voltage change rate during the nth turn-off period is greater than the second grounding safety threshold.

9. The apparatus according to claim 7, characterized in that, The device further includes: The tube-down timing module is used to determine the nth turn-on command time, the nth turn-off command time, and the (n+1)th turn-on command time for each bridge arm tube-down based on the turn-on and turn-off commands of each power switching device of the traction converter. The lower tube voltage module is used to determine the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm lower tube based on the dead time and ground voltage of the traction converter, according to the nth turn-on command time, nth turn-off command time, and n+1th turn-on command time of each bridge arm lower tube, as well as the ground voltage corresponding to the nth actual turn-on time, nth actual turn-off time, and n+1th actual turn-on time of each bridge arm lower tube.

10. The apparatus according to claim 9, characterized in that, The device further includes: The lower pipe conduction period module is used to determine the nth conduction period of each bridge arm lower pipe based on the nth actual conduction time and the nth actual shutdown time of each bridge arm lower pipe. The lower limit module is used to determine the duration of the voltage below the lower limit during the nth conduction period of each bridge arm lower pipe, based on the preset lower limit of the ground voltage and the ground voltage corresponding to the nth actual conduction time and the nth actual turn-off time of each bridge arm lower pipe. The first proportional value module is used to determine the lower-than-ground voltage proportional value based on the nth actual turn-on time, the nth actual turn-off time, and the duration of the voltage below the lower limit value of each bridge arm lower pipe.

11. The apparatus according to claim 10, characterized in that, The device further includes: The upper pipe conduction period module is used to determine the nth conduction period of each bridge arm upper pipe based on the nth actual conduction time and the nth actual shutdown time of each bridge arm upper pipe. The upper limit module is used to determine the duration of the voltage exceeding the upper limit during the nth conduction period of each bridge arm pipe, based on the preset upper limit of the ground voltage and the ground voltage corresponding to the nth actual conduction time and the nth actual turn-off time of each bridge arm pipe. The second proportional value module is used to determine the proportional value above the ground voltage based on the nth actual turn-on time, the nth actual turn-off time, and the duration above the upper limit value of each bridge arm pipe.

12. The apparatus according to claim 11, characterized in that, The device further includes: The DC bus early warning module is used to determine the DC bus grounding early warning result based on the first comparison result, the second comparison result, the lower grounding voltage ratio value, and the higher grounding voltage ratio value.

13. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method according to any one of claims 1 to 6.

14. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that enables a computer to execute the method according to any one of claims 1 to 6.

15. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method according to any one of claims 1 to 6.

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