A method and device for sampling and triggering current of switch cabinet opening and closing action

Abstract

The present invention discloses a method and device for sampling and triggering the action current of a switch cabinet, which relates to the technical field of the action current sampling of a switch cabinet, and comprises the following steps: sampling the current once, sampling the data of the duration Ts; calculating the sum U1 of the amplitude values ​​of the data of the duration Ts, comparing the relationship between U1 and the lower threshold A0, comparing the relationship between U1 and the upper threshold A1, and sampling the next data of the duration Ts; calculating the sum U2 of the amplitude values ​​of the data of the duration Ts just sampled; judging the relationship between U2 and U1, if U2>U1, judging the first and second groups of register data as the action current data of the switch cabinet, triggering the action current sampling; saving the action current data just sampled to the register whose address starts from 2n+1; and outputting the action current data. The present invention has the beneficial effects of eliminating the influence of interference, reducing the probability of false triggering and missed triggering, improving the integrity of the action current data, and making the extracted parameters more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of switch cabinet current sampling, and in particular to a switch cabinet opening and closing action current sampling triggering method and device. Background Art

[0002] The switchgear is the core equipment of the power transmission and distribution system, and is responsible for the current on and off of the switchgear. The switchgear realizes the connection and disconnection of the current by controlling the opening and closing of the internal break. The opening and closing actions of the switchgear are mostly realized by driving the corresponding mechanism with the motor. During the opening and closing actions, the working current of the motor changes in a fixed pattern. The current of the entire action process is recorded, and the current waveform formed with time as the axis is relatively fixed. If the internal equipment of the switchgear is abnormal, such as the transmission parts are stuck, the springs are aged, etc., the action current waveform of the opening and closing process will also change accordingly. Therefore, by monitoring the action current of the switchgear opening and closing, the working status of the switchgear can be monitored.

[0003] When the switch cabinet is powered normally, the break is in the closed state. Only when the equipment is powered off for maintenance, the switch cabinet has a need to cut off and supply power, and the switch cabinet will have corresponding opening and closing actions. Once the monitoring equipment misses the correct waveform sampling opportunity of the opening and closing action current, it will need to wait for the next maintenance. Therefore, accurately triggering the opening and closing action current sampling is the key to switch cabinet monitoring.

[0004] The key issue in monitoring the opening and closing action current of the switch cabinet is when to trigger the current sampling. Because these operating actions of the switch cabinet are sudden actions, the monitoring equipment cannot predict the start time of the switch cabinet action, and the duration of the opening and closing actions of the switch cabinet is very short, generally not exceeding 60ms. In order to ensure the integrity of the action current sampling, once the current sampling is triggered, the equipment will continue to sample for a period of time. After the sampling is completed, the equipment enters the data processing and transmission stage. The data processing and transmission takes a long time, more than 5s. From the triggering of the action current sampling to the end of the processing and transmission of the sampled data, the equipment cannot sample again. During this period of time, it is enough for the switch cabinet to complete more than 80 opening and closing actions. Obviously, if it is triggered by mistake, it is easy to miss the real action current sampling, and the monitoring equipment will not play its due role.

[0005] If the trigger is too early, the monitoring device will sample a bunch of invalid data and enter the time-consuming data processing stage. If the real action comes at this time, the device cannot start sampling because it is in the data processing stage, and the opportunity to sample the action current of the switch cabinet will be missed; if the trigger is too late, there will be missed sampling, and some action current data will be missing, resulting in incomplete action current waveforms. It is impossible to accurately calculate the key parameters of the switch cabinet action, such as the opening time, closing time, opening speed, and closing speed, and the purpose of monitoring cannot be achieved. Therefore, false triggering and untimely triggering are fatal defects for switch cabinet monitoring equipment.

[0006] The existing switchgear action current monitoring method is to sample at a fixed Ts interval, calculate the sum of the amplitude values ​​of the signal sampling data, and compare it with the preset threshold A0 to determine whether the switchgear has an opening and closing action. If it is determined that there is an opening and closing action, the action current sampling is triggered. This method has very obvious defects. Common problems are that it is easy to be missampled by pulse interference, easy to be missampled by ripple interference, and easy to have incomplete action current data sampling. This method of relying only on a lower threshold to determine whether the switchgear has an action and whether it is necessary to trigger current sampling has great limitations, a high false trigger rate, and often misses and wrong samples. The sampled action current data is incomplete, resulting in low accuracy of the extracted parameters.

[0007] Therefore, technicians in this field are committed to developing a switch cabinet opening and closing action current sampling triggering method to solve the problems of inaccurate triggering time, missing action current data, and incomplete action current waveform caused by disturbance current signals, pulse interference signals or ripple interference signals. Summary of the invention

[0008] The conventional sampling trigger mechanism is realized by presetting a fixed threshold judgment. Figure 1The flow chart of the switch cabinet action current sampling triggering method based on the lower threshold in the prior art is as follows: when the switch cabinet has no opening and closing action, the motor current is set to 0, and the current amplitude sampled in a time period is accumulated, and the sum should be 0 (or a data very close to 0); when the switch cabinet has an opening and closing action, the motor current will increase rapidly. At this time, the current amplitude sampled in Ts is accumulated, and the sum should be much greater than zero. Ideally, only a suitable lower threshold A0 needs to be preset, and the current amplitude within the Ts time is accumulated and compared with the preset lower threshold A0. If it exceeds A0, it can be considered that the switch cabinet has an operation action, triggering the action current sampling, and capturing the switch cabinet action current waveform. If the current amplitude accumulated within the Ts time is lower than the threshold, it is considered that the switch cabinet has no action and enters the next Ts sampling stage. The conventional method has a high false trigger rate and often samples a lot of invalid data. In order to improve accuracy, the value of the lower threshold A0 is deliberately increased. Since the start time of pre-sampling is random and cannot coincide with the start time of opening and closing, when there is an opening and closing action, the data in the pre-sampled Ts time period often contains some current data components without opening and closing actions, which cannot reach the threshold value of A0 and will not trigger subsequent sampling. It is necessary to wait for the next Ts pre-sampling to trigger the action current sampling, resulting in missed sampling and missing of the sampled action current data. Figure 2 and Figure 3 This is a current waveform diagram of the closing and opening action of the switch cabinet monitored by the conventional method in the prior art. Using the sampling method in the prior art, the sampled action current waveform will be missing, and the missing time can be up to Ts.

[0009] The time for the switchgear to open and close is extremely short, and generally does not exceed 60ms under normal circumstances. Therefore, the pre-sampling time Ts used to calculate whether the switchgear has an opening and closing action cannot be too long, otherwise the amount of data to be processed is too large, the time consumption is too long, and the probability of mis-sampling will be greatly increased. Assuming that after the opening and closing action is started, the sum of the current amplitude values ​​in the first Ts time period is A, the conventional method has only one lower threshold judgment. In order to reduce the probability of mis-sampling, the value of A0 is usually very high, generally A0 = 0.9*A.

[0010] According to actual tests, if there is interference within the Ts time period, especially pulse interference and ripple interference, the sum of the sampled signal amplitude values ​​may easily exceed the preset lower threshold A0, resulting in false triggering.

[0011] When the switchgear equipment is aging or faulty, the opening and closing operation time will become longer. To completely capture the current waveform of the opening and closing operation, the corresponding sampling time also needs to be extended. Considering the equipment characteristics and actual test conditions, the monitoring time length for the opening and closing operation of the switchgear is more than twice the normal opening and closing operation time. Processing and analyzing the sampling data for such a long time takes more than 5 seconds in total. During these 5 seconds, the monitoring equipment cannot sample. If a real opening and closing operation occurs in the switchgear within these 5 seconds, the monitoring equipment will miss the monitoring of the switchgear operation.

[0012] In view of the above defects of the prior art, the technical problem to be solved by the present invention is that the conventional triggering method has inaccurate triggering moments, serious mis-triggering and missed-triggering phenomena due to disturbing current signals, pulsed interference signals or ripple interference signals, resulting in missing action current data and incomplete action current waveforms.

[0013] To achieve the above object, the present invention provides a method for sampling and triggering the opening and closing action current of a switchgear, and the method includes the following steps:

[0014] Step 1: Sample the current of the opening and closing circuit of the switchgear, sample the data for a duration of Ts, with a single sampling time length of Tc, and store the data in the first group of registers with addresses from 1 to n;

[0015] Step 2: Calculate the sum of the amplitude values of the data for the duration of Ts, denoted as U1;

[0016] Step 3: Compare the relationship between U1 and the lower threshold A0. If U1 < A0, it is determined that the sampled current is the disturbing current of the motor power line, delete the data in the first group of registers, and return to Step 1 to start over; if U1 ≥ A0, continue with the subsequent judgment;

[0017] Step 4: Compare the relationship between U1 and the upper threshold A1. If U1 > A1, it is determined that the sampled current is the pulsed interference current on the motor power line, delete the data in the first group of registers, and return to Step 1 to start over; if U1 ≤ A1, continue with the subsequent judgment;

[0018] Step 5: Sample the next data for a duration of Ts, with a single sampling time length of Tc, and store the data in the second group of registers with addresses from n + 1 to 2n in the buffer;

[0019] Step 6: Calculate the sum of the amplitude values of the next data for the duration of Ts just sampled, denoted as U2;

[0020] Step 7: Judge the relationship between U2 and U1. If U2 ≤ U1, it is determined that the sampled current is the ripple interference current on the motor power line, delete the data in the first group of registers and the data in the second group of registers, and return to Step 1 to start over;

[0021] Step 8: If U2>U1, determine that the first group of register data and the second group of register data are switch cabinet action current data, and trigger action current sampling;

[0022] Step 9: Save the action current data just sampled to registers starting from address 2n+1 in chronological order, and form the action current data with the first group of register data and the second group of register data.

[0023] Step 10: Output the operating current data.

[0024] In another preferred embodiment of the present invention, the value of n is determined by the sampling time Ts and the single sampling time length Tc, n=Ts / Tc.

[0025] In another preferred embodiment of the present invention, the sampling time Ts is 6 ms.

[0026] In another preferred embodiment of the present invention, the single sampling time length Tc is 0.1 ms.

[0027] In another preferred embodiment of the present invention, the lower threshold A0 is set according to the sum of the data amplitude values ​​within the initial period Ts of the switch cabinet opening and closing action.

[0028] Preferably, the lower threshold A0 value is greater than 0.

[0029] In a preferred embodiment of the present invention, the upper threshold A1 is set based on the following characteristics: if the switch cabinet is normal, the sum of the data amplitude values ​​within the first Ts time period after the opening and closing action of the switch cabinet is started has a fixed upper limit (the upper limit value is slightly different for different models of equipment); if the switch cabinet is abnormal, the initial current rising slope will decrease after the opening and closing action is started, and the sum of the data amplitude values ​​within the first Ts time period after the opening and closing action of the switch cabinet is started will become smaller than the normal value.

[0030] Preferably, the upper threshold value A1 is greater than the lower threshold value A0.

[0031] In a preferred embodiment of the present invention, the action current sampling duration is 240 ms.

[0032] The present invention also provides a switch cabinet opening and closing action current sampling device, and the device adopts the switch cabinet opening and closing action current sampling triggering method.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The use of dual threshold judgment can eliminate the influence of pulse interference and solve the problem of false triggering caused by pulse interference;

[0035] 2. The use of unidirectional incremental judgment can eliminate the influence of ripple interference and solve the problem of false triggering caused by ripple interference.

[0036] 3. The method of dynamically storing pre-sampled data in a fixed address register solves the problem that the conventional method has incomplete action current waveform, cannot accurately calculate key equipment parameters, and cannot effectively monitor the status of switch cabinet equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flow chart of a conventional switch cabinet action current sampling triggering method based on a lower threshold in the prior art;

[0038] Figure 2 It is a current waveform diagram of the closing action of the switch cabinet monitored by conventional methods in the prior art;

[0039] Figure 3 It is a current waveform diagram of the switchgear opening action monitored by conventional methods in the prior art;

[0040] Figure 4 It is a sampling process flow chart of a switch cabinet action current sampling triggering method based on dynamic storage of pre-sampled data and multi-dimensional judgment of a preferred embodiment of the present invention;

[0041] Figure 5 It is a sampling process flow chart of a switch cabinet action current sampling triggering method based on dynamic storage of pre-sampled data and multi-dimensional judgment of a fixed address register, which is a specific example of a preferred embodiment of the present invention;

[0042] Figure 6 It is a current waveform diagram of the switch cabinet closing action monitored by a preferred embodiment of the present invention;

[0043] Figure 7 It is a current waveform diagram of the switch cabinet opening action monitored by a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0044] The following describes several preferred embodiments of the present invention with reference to the drawings in the specification, so that the technical content is clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0045] refer to Figure 4 , is a sampling process flow chart of a switch cabinet action current sampling triggering method based on dynamic storage of pre-sampled data and multi-dimensional judgment of a preferred embodiment of the present invention, and is processed in the following steps:

[0046] Step 1: Sample the current of the switch cabinet's closing and opening circuits for a data duration of Ts, with a single sampling time length of Tc, and store this data in the first group of registers with addresses from 1 to n;

[0047] Step 2: Calculate the sum of the amplitude values of the data for the duration of Ts, denoted as U1, and perform the following multi-dimensional judgment;

[0048] Step 3: Compare the relationship between U1 and the lower threshold A0. If U1 < A0, it is determined that the sampled current is the disturbance current of the motor power line. Delete the data in the first group of registers and return to Step 1 to start over; if U1 ≥ A0, continue with the subsequent judgment;

[0049] Step 4: Compare the relationship between U1 and the upper threshold A1. If U1 > A1, it is determined that the sampled current is the pulse interference current on the motor power line. Delete the data in the first group of registers and return to Step 1 to start over; if U1 ≤ A1, continue with the subsequent judgment;

[0050] Step 5: Sample the next data for a duration of Ts, with a single sampling time length of Tc, and store the data for the next duration of Ts in the second group of registers with addresses from n + 1 to 2n in the buffer;

[0051] Step 6: Calculate the sum of the amplitude values of the just-sampled data for the next duration of Ts, denoted as U2;

[0052] Step 7: Judge the relationship between U2 and U1. If U2 ≤ U1, it is determined that the sampled current is the ripple interference current on the motor power line. Delete the data in the first group of registers and the second group of registers, and return to Step 1 to start over;

[0053] Step 8: If U2 > U1, determine that the data in the first group of registers and the second group of registers are the action current data of the switch cabinet, and trigger the action current sampling;

[0054] Step 9: Save the just-sampled action current data in sequence according to the time sequence to the registers starting from address 2n + 1, and form the action current data together with the data in the first group of registers and the second group of registers;

[0055] Step 10: Output the action current data.

[0056] Compare the relationship between U1 and the lower threshold A0. If U1 < A0, it is determined that the sampled current is the disturbance current of the motor power line. If U1 > A0, continue with the subsequent judgment. Compare the relationship between U1 and the upper threshold A1. If U1 > A1, it is determined that the sampled current is the pulse interference current on the motor power line. If U1 ≤ A1, continue with the subsequent judgment. Judge the relationship between U2 and U1. If U2 ≤ U1, the sampled current is the ripple interference current on the motor power line. If U2 > U1, it is determined that the first group of register data and the second group of register data are the switchgear action current data, and trigger the action current sampling.

[0057] Reference Figure 5 , as a specific example of a preferred embodiment of the present invention, the switchgear action current sampling trigger method based on sliding sampling and multi-dimensional judgment is processed as follows:

[0058] Step 1: Sample the current of the switchgear closing and opening circuits for 6 mS, with a single sampling time length of 0.1 mS, and store the data in the first group of registers at addresses 1 to 60.

[0059] Step 2: Calculate the sum of the data amplitude values for the duration of Ts, denoted as U1, and perform the following multi-dimensional judgment.

[0060] Step 3: Compare the relationship between U1 and the lower threshold A0. If U1 < A0, it can be determined that the sampled current is the disturbance current of the motor power line. Delete the first group of register data and return to Step 1 to start over. Otherwise, continue with the subsequent judgment.

[0061] Step 4: Compare the relationship between U1 and the upper threshold A1. If U1 > A1, it can be determined that the sampled current is the pulse interference current on the motor power line. Delete the first group of register data and return to Step 1 to start over. Otherwise, continue with the subsequent judgment.

[0062] Step 5: Continue to sample the data for 6 mS, with a single sampling time length of 0.1 mS, and store the data in the second group of registers at addresses 61 to 120 of the buffer.

[0063] Step 6: Calculate the sum of the data amplitude values for the just sampled 6 mS duration, denoted as U2.

[0064] Step 7: Judge the relationship between U2 and U1. If U2 ≤ U1, the sampled current is the ripple interference current on the motor power line. Delete the first and second groups of register data and return to Step 1 to start over. Otherwise, continue with the subsequent process.

[0065] Step 8: If U2 > U1, when it is determined that the two data packets for the duration of Ts are the switchgear action current, trigger the action current sampling.

[0066] Step 9, save the action current data just sampled to the registers starting from address 121 in chronological order, and combine them with the first two groups of data to form the action current data;

[0067] Step 10: Output the operating current data.

[0068] At the initial stage of the switch cabinet opening and closing action, the current amplitude increases, and the sum of the current amplitude values ​​in the Ts time period must be greater than 0. Based on this, the lower threshold A0 can be set. If the sum of the current amplitude values ​​sampled in the Ts time period is lower than the lower threshold A0, it means that the sampled current is the disturbance current on the motor power line. At the same time, according to the characteristics of the switch cabinet abnormality and the current rising slope will only decrease in the initial stage of the opening and closing action, an upper threshold A1 is added, and a double threshold judgment is adopted. If the sum of the current amplitude values ​​sampled in the Ts time period is greater than the upper threshold A1, it means that the sampled current is a pulse interference signal on the motor power line.

[0069] The present invention adopts multi-dimensional judgment and does not rely solely on the lower threshold. Therefore, there is no need to deliberately increase the value of A0. It only needs to be slightly higher than the normal disturbance current on the power line. Assuming that the sum of the current amplitude values ​​in the first Ts time period after the opening and closing action is started is A, A0=0.2*A is taken in a preferred embodiment of the present invention. With this setting, even if there is some non-opening and closing action data in the pre-sampled data, the subsequent action current sampling can be triggered normally, and there will be no missing sampling phenomenon. In the extreme case, even if there is missing sampling, the missing time will not exceed 1ms, and this missing does not affect the accuracy of the extracted characteristic parameters.

[0070] In a preferred embodiment of the present invention, the upper threshold A1 is set based on the following characteristics: if the switch cabinet is normal, the sum of the data amplitude values ​​within the first Ts time period after the opening and closing action of the switch cabinet is started has a fixed upper limit (the upper limit value is slightly different for different models of equipment); if the switch cabinet is abnormal, the initial current rising slope will decrease after the opening and closing action is started, and the sum of the data amplitude values ​​within the first Ts time period after the opening and closing action of the switch cabinet is started will become smaller than the normal value.

[0071] The method of dynamically storing pre-sampled data in a fixed address register can completely retain the first two pre-sampled data used to determine whether it is an action current, ensuring that the action current data is complete and there will be no missing action current data. The maximum missing rate of the closing action current obtained by the conventional method is 10.9% (the closing action time is calculated based on the conventional average of 55mS), and the maximum missing rate of the opening action current data is 17.14% (the opening action time is calculated based on the conventional average of 35mS); after the method of dynamically storing pre-sampled data in a fixed address register is adopted, the action waveform is complete and there is no missing.

[0072] The opening and closing actions of the switch cabinet are ultimately realized by the spring mechanism. If the spring becomes fatigued or worn after long-term use, or if abnormal conditions such as jamming occur, the opening and closing time will only become longer, not shorter. In other words, the action current of the abnormal switch cabinet can only decrease, not increase, compared with the normal switch cabinet in the early period of action start, and the corresponding action couple amplitude value will only be smaller. That is, in the first Ts time period, the sum of the amplitude values ​​of the action current U1 is a relatively fixed value under normal circumstances, with a clear upper limit value. When the equipment fails, U1 will only decrease, not increase.

[0073] According to the above analysis and a large amount of data verification, it is shown that the sum of the amplitude values ​​of the sampled data in the Ts time period, U1, always changes within a certain range under normal circumstances. When the equipment is abnormal, the U1 value will only decrease and not increase. When U1 ≥ A1, it can be determined that the sampled current is not the switch cabinet action current, but other pulse interference signals.

[0074] The pulse interference on the motor power line is often large in amplitude and high in rising slope. The sum of the amplitude values ​​of the sampled data in the Ts period, U1, is larger than the current sampling data of the switch cabinet under the same conditions. By adding an upper threshold and using the upper and lower double threshold judgment method, the influence of the pulse interference signal can be eliminated.

[0075] Ripple interference is a common interference on the power line, showing a certain regular periodicity. The amplitude of these interference signals is equivalent to the current amplitude at the initial stage of the switch cabinet operation. The method of calculating the signal amplitude in the Ts time period can easily cause false triggering, while the opening and closing action current of the switch cabinet increases unidirectionally in the early stage of startup. By using the difference between the two, the ripple interference signal and the action current signal of the switch cabinet can be distinguished by comparing the change in the amplitude value of the signal per unit time.

[0076] The specific method is to determine that the pre-sampled data sampled for the first time is not pulse interference and disturbance interference, and then sample the Ts duration data again to calculate the sum of its amplitude values ​​U2. According to the characteristics of the unidirectional increase of the current in the initial stage of the switch cabinet operation, U2 must be larger than U1, otherwise it is certain that it is not the operating current of the switch cabinet, but a ripple interference signal, and pre-sampling needs to be restarted.

[0077] Since the ripple interference signal is periodic, the sum of its amplitude values ​​does not increase unidirectionally. Through this judgment, the ripple interference can be eliminated.

[0078] like Figure 6 As shown in FIG. 1 , it is a current waveform diagram of the switch cabinet closing action monitored by a preferred embodiment of the present invention, such as Figure 7It is a waveform diagram of the switch cabinet opening action current monitored by a preferred embodiment of the present invention. After sampling and processing using the fixed address register dynamically storing pre-sampled data and the switch cabinet action current sampling trigger method of multi-dimensional judgment described in the present invention, the obtained sampling action current waveforms of the switch opening and closing currents are complete and without any omissions.

[0079] In a preferred embodiment of the present invention, the pre-sampling time Ts is 6 ms. The time length may also be other times, such as 5 ms or 7 ms. Such a change does not affect the essence of the present invention.

[0080] In a preferred embodiment of the present invention, the single sampling time length Tc is 0.1 ms. The time length may also be other times, and such a change does not affect the essence of the present invention.

[0081] The value of n is determined by the sampling time Ts and the single sampling time length Tc, n=Ts / Tc.

[0082] In a preferred embodiment of the present invention, the value of n is 60.

[0083] In a preferred embodiment of the present invention, the action current sampling time length is 240ms. In other embodiments, other sampling time lengths may be used, and such changes do not affect the essence of the present invention.

[0084] In one embodiment of the present invention, in a switch cabinet opening and closing action current sampling device, the above-mentioned switch cabinet opening and closing action current sampling triggering method is adopted.

[0085] The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in the field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for sampling and triggering current of a switch cabinet opening and closing action, characterized in that: The method includes the following steps: Step 1: Sample the current in the switching-on and switching-off circuits of the switchgear for a data duration of Ts, with a single sampling time length of Tc, and store the data in the first set of registers with addresses from 1 to n; Step 2: Calculate the sum of the amplitude values of the data during the Ts duration, denoted as U1; Step 3: Compare the relationship between U1 and the lower threshold A0. If U1 < A0, it is determined that the sampled current is the disturbance current of the motor power line, delete the data in the first set of registers, and return to Step 1 to start over; if U1 ≥ A0, continue with the subsequent judgment; Step 4: Compare the relationship between U1 and the upper threshold A1. If U1 > A1, it is determined that the sampled current is the pulse interference current on the motor power line, delete the data in the first set of registers, and return to Step 1 to start over; if U1 ≤ A1, continue with the subsequent judgment; Step 5: Sample the next data for a duration of Ts, with a single sampling time length of Tc, and store the data of the next Ts duration in the second set of registers with addresses from n + 1 to 2n in the buffer; Step 6: Calculate the sum of the amplitude values of the just-sampled data of the next Ts duration, denoted as U2; Step 7: Judge the relationship between U2 and U1. If U2 ≤ U1, it is determined that the sampled current is the ripple interference current on the motor power line, delete the data in the first set of registers and the second set of registers, and return to Step 1 to start over; Step 8: If U2 > U1, determine that the data in the first set of registers and the second set of registers are the action current data of the switchgear, and trigger the action current sampling; Step 9: Save the just-sampled action current data in sequence according to the time sequence to the registers starting from address 2n + 1, and form the action current data together with the data in the first set of registers and the second set of registers; Step 10: Output the action current data.

2. The switch cabinet opening and closing action current sampling triggering method according to claim 1 is characterized in that: In Step 1, the value of n is determined by the sampling time Ts and the single sampling time length Tc, and n = Ts / Tc.

3. The switch cabinet opening and closing action current sampling triggering method according to claim 1 is characterized in that: In Step 1, the sampling time Ts is 6 ms.

4. The switch cabinet opening and closing action current sampling triggering method according to claim 3 is characterized in that: In Step 1, the single sampling time length Tc is 0.1 ms.

5. The switch cabinet opening and closing action current sampling triggering method according to claim 1, characterized in that: The lower threshold A0 is set according to the sum of the amplitude values of the data within the first Ts duration after the start of the switching-on and switching-off actions of the switchgear.

6. The switch cabinet opening and closing action current sampling triggering method according to claim 5 is characterized in that: The value of the lower threshold A0 is greater than 0.

7. The switch cabinet opening and closing action current sampling triggering method according to claim 1 is characterized in that: The upper threshold A1 is set based on the fact that if the switchgear is normal, there is a fixed upper limit for the sum of the amplitude values of the data within the first Ts duration after the start of the switching-on and switching-off actions of the switchgear; if the switchgear is abnormal, the initial current rising slope during the start of the switching-on and switching-off actions will decrease, and the sum of the amplitude values of the data within the first Ts duration after the start of the switching-on and switching-off actions of the switchgear will be smaller compared to the normal value.

8. The switch cabinet opening and closing action current sampling and triggering method according to claim 7, characterized in that: The value of the upper threshold A1 is greater than the value of the lower threshold A0.

9. The switch cabinet opening and closing action current sampling triggering method according to claim 1, characterized in that: In Step 8, the action current sampling duration is 240 ms.

10. A current sampling device for the opening and closing action of a switch cabinet, characterized in that: The device adopts the method for triggering the sampling of the switching-on and switching-off action current of the switchgear as described in Claim 1.

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