An online monitoring system for the mechanical characteristics of switchgear

Abstract

This application provides an online monitoring system for the mechanical characteristics of a switchgear, comprising: a position sensor, a current sensor, and a processing unit; the position sensor is used to detect the first speed value of the circuit breaker contacts during the opening process and the second speed value during the closing process; the current sensor is used to detect the opening current value and the closing current value of the operating mechanism; the processing unit is configured to generate a first speed curve, a second speed curve, an opening current waveform, and a closing current waveform; calculate the opening displacement during the opening process based on the first position curve; calculate the closing displacement during the closing process based on the second position curve; calculate the opening time during the opening process based on the opening current waveform; and calculate the closing time during the closing process based on the closing current waveform. Through the above structure, the status of the circuit breaker equipment can be accurately and in real time, improving the reliability of circuit breaker operation and power supply, and avoiding safety accidents caused by untimely detection.

Description

Technical Field

[0001] This disclosure generally relates to the field of switchgear equipment technology, and specifically to an online monitoring system for the mechanical characteristics of switchgear. Background Technology

[0002] Switchgear is a common piece of equipment in substations, characterized by its compact structure, small footprint, and light weight. It is widely used in 10kV and 35kV power systems, and its main functions are to switch, control, and protect incoming and outgoing lines, reactive power compensation equipment, and station service transformers. Switchgear includes circuit breakers and operating mechanisms. The operating mechanism responds to external control signals to control the circuit breakers to open or close.

[0003] Mechanical characteristics are the most critical indicator characterizing the performance of switchgear, and their parameters directly reflect the arc-extinguishing performance of the switchgear. Substandard mechanical characteristics will lead to problems such as arc-extinguishing chamber burnout, excessively long arc-extinguishing time, and incomplete arc extinguishing, and may even cause equipment burnout, explosion, and other malfunctions, directly affecting the safe and stable operation of the power grid.

[0004] Currently, the main method for mechanical characteristic testing is "periodic maintenance," which involves preventative testing every five years in conjunction with the company's power outage plan. However, this often results in maintenance only being carried out after a power outage caused by equipment failure, following a dispatch and maintenance notification. By this time, the circuit breaker has usually suffered irreversible damage, and the testing method is also highly unreliable. Therefore, there is an urgent need to develop an online mechanical characteristic monitoring system to accurately and in real-time monitor the status of circuit breaker equipment, thereby improving the reliability of circuit breaker operation and power supply. Summary of the Invention

[0005] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide an online monitoring system for the mechanical characteristics of switchgear that can solve the above-mentioned technical problems.

[0006] This application provides an online monitoring system for the mechanical characteristics of a switchgear. The switchgear includes a circuit breaker and an operating mechanism. The operating mechanism is used to control the circuit breaker to open or close in response to an external control signal. The online monitoring system for the mechanical characteristics of the switchgear includes:

[0007] A speed sensor is used to detect a first speed value of the circuit breaker contacts during the opening process and a second speed value during the closing process.

[0008] A current sensor is used to detect the opening current value and closing current value of the operating mechanism;

[0009] Processing unit, the processing unit being configured to:

[0010] A first velocity curve is obtained based on the first velocity value; a second velocity curve is obtained based on the second velocity value.

[0011] Based on the tripping current value, the tripping current waveform is obtained; based on the closing current value, the closing current waveform is obtained.

[0012] Calculate the tripping time, which is the time interval between the start time of the tripping current waveform and the moment of tripping in the first velocity curve; the moment of tripping is the moment when the absolute value of the velocity in the first velocity curve is the largest.

[0013] Calculate the closing time, which is the time interval between the start time of the closing current waveform and the point of contact in the first velocity curve; the point of contact is the moment when the absolute value of the velocity is the largest in the second velocity curve.

[0014] According to the technical solution provided in the embodiments of this application, the online monitoring system for mechanical characteristics of the switchgear further includes a filtering unit, which is used to filter the opening current waveform and the closing current waveform.

[0015] According to the technical solution provided in the embodiments of this application, the online monitoring system for the mechanical characteristics of the switchgear further includes a first adaptive calculation unit, which is used to determine the start time of the tripping current waveform; the first adaptive calculation unit is configured to:

[0016] Obtain the tripping current waveforms during multiple tripping processes;

[0017] The circuit breaker current waveform is decomposed into wavelet coefficients C(n) corresponding to the nth circuit breaker current waveform, where n≥1.

[0018] The first current threshold U a (n) is the starting time of the tripping current waveform during the nth tripping process; the tripping time for each tripping process is calculated; the first current threshold U a (n) is calculated according to formula (i):

[0019]

[0020] Wherein, U1 is the first initial current threshold, and u1 is the first set step size;

[0021] Starting from n=2, when the difference between the opening times of two adjacent opening processes is less than a set value and the difference of the wavelet coefficients is greater than 0, the first current threshold corresponding to the smaller value of the opening times of the two opening processes is taken as the standard value and used to determine the starting time of the opening current waveform.

[0022] According to the technical solution provided in the embodiments of this application, a second adaptive calculation unit is further included. The second adaptive calculation unit is used to determine the start time of the closing current waveform; the second adaptive calculation unit is configured to:

[0023] The closing current waveform of each closing process is decomposed into wavelet coefficients C(m) for each closing current waveform, where m≥1.

[0024] The second current threshold U b (m) is the starting time of the closing current waveform during the m-th closing process; the closing time of each closing process is calculated; the second current threshold U b (m) is calculated according to formula (II):

[0025]

[0026] Wherein, U2 is the second initial current threshold, and u2 is the second set step size;

[0027] Starting from m=2, when the difference between the closing times of two adjacent closing processes is less than a set value and the difference of the wavelet coefficients is greater than 0, the second current threshold corresponding to the smaller value of the closing times of the two closing processes is taken as the standard value and used to determine the starting time of the closing current waveform.

[0028] According to the technical solution provided in the embodiments of this application, the processing unit is further configured to:

[0029] Calculate the closing overtravel; the closing overtravel is the displacement from the moment of contact to the moment when the velocity value is zero in the second velocity curve.

[0030] According to the technical solution provided in the embodiments of this application, the online monitoring system for mechanical characteristics of switchgear also includes a position sensor, which is used to detect the first position signal of the circuit breaker contacts during the opening process and the second position signal during the closing process.

[0031] The processing unit is also configured to:

[0032] Based on the first position signal, calculate the opening displacement during the opening process; based on the second position signal, calculate the closing displacement during the closing process.

[0033] According to the technical solution provided in the embodiments of this application, the operating mechanism includes:

[0034] A drive unit is connected to the contacts of the circuit breaker; the drive unit has a first state and a second state; in the first state, the drive unit drives the contacts to open; in the second state, the drive unit drives the contacts to close.

[0035] The control unit has a tripping coil and a closing coil connected to the drive unit; when the tripping coil is energized, it controls the drive unit to switch to the first state, and when the closing coil is energized, it controls the drive unit to switch to the second state.

[0036] According to the technical solution provided in the embodiments of this application, the current sensor includes a first current sensor and a second current sensor;

[0037] The first current sensor is connected to the trip coil and is used to detect the trip current waveform of the trip coil;

[0038] The second current sensor is connected to the closing coil and is used to detect the closing current waveform of the closing coil.

[0039] According to the technical solution provided in the embodiments of this application, the position sensor is connected to the drive unit, and the speed sensor is connected to the drive unit.

[0040] According to the technical solution provided in the embodiments of this application, the input terminal of the processing unit is connected to a wireless transmission module, and the position sensor, current sensor and speed sensor are wirelessly connected to the input terminal of the wireless transmission module.

[0041] According to the technical solution provided in the embodiments of this application, a filtering module is installed between the input end of the processing unit and the output end of the wireless transmission module.

[0042] The beneficial effects of this application are as follows: By detecting the opening and closing current values ​​of the operating mechanism using a current sensor, the processing unit can acquire the current waveforms during the opening and closing processes, thereby obtaining the current initiation time; by detecting the first speed value of the circuit breaker contacts during the opening process and the second speed value during the closing process using a speed sensor, the processing unit can obtain the exact moment of opening during the opening process and the exact moment of closing during the closing process; thus, the opening and closing times can be calculated. This online monitoring system for the mechanical characteristics of the switchgear enables accurate and real-time monitoring of the circuit breaker equipment status, improving the reliability of circuit breaker operation and power supply, and preventing safety accidents caused by untimely detection. Attached Figure Description

[0043] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0044] Figure 1 The schematic diagram of the online monitoring system for the mechanical characteristics of switchgear provided in this application;

[0045] Figure 2 The circuit diagram of the online monitoring system for the mechanical characteristics of the switchgear provided in this application.

[0046] Numbering on the map:

[0047] 1. Position sensor; 2. Current sensor; 3. Speed ​​sensor; 4. Processing unit; 5. Wireless transmission module; 6. Touch screen; 7. Filtering module; 8. Power supply module; 9. First adaptive calculation unit; 10. Second adaptive calculation unit. Detailed Implementation

[0048] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0049] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0050] Example 1

[0051] Please refer to Figure 1 This application provides a schematic diagram of an online monitoring system for the mechanical characteristics of a switchgear. The switchgear includes a circuit breaker and an operating mechanism. The operating mechanism is used to control the circuit breaker to open or close in response to an external control signal, including:

[0052] Speed ​​sensor 3 is used to detect the first speed value of the circuit breaker contacts during the opening process and the second speed value during the closing process;

[0053] Current sensor 2, which is used to detect the opening current value and closing current value of the operating mechanism;

[0054] Processing unit 4, the processing unit 4 being configured to:

[0055] A first velocity curve is obtained based on the first velocity value; a second velocity curve is obtained based on the second velocity value.

[0056] Based on the tripping current value, the tripping current waveform is obtained; based on the closing current value, the closing current waveform is obtained.

[0057] Calculate the tripping time, which is the time interval between the start time of the tripping current waveform and the moment of tripping in the first velocity curve; the moment of tripping is the moment when the absolute value of the velocity in the first velocity curve is the largest.

[0058] Calculate the closing time, which is the time interval between the start time of the closing current waveform and the point of contact in the first velocity curve; the point of contact is the moment when the absolute value of the velocity is the largest in the second velocity curve.

[0059] In this embodiment, the processing unit 4 is a DSP28335.

[0060] As those skilled in the art will know, the operating mechanism is used to control the opening or closing of the circuit breaker. It can energize its internal coil in response to an external control signal, thereby causing the drive unit to open or close the circuit breaker contacts. For example, the operating mechanism could be a CT26 spring operating mechanism.

[0061] For ease of understanding by those skilled in the art, the operating mechanism specifically includes:

[0062] A drive unit is connected to the contacts of the circuit breaker; the drive unit has a first state and a second state; in the first state, the drive unit drives the contacts to open; in the second state, the drive unit drives the contacts to close.

[0063] The control unit has a tripping coil and a closing coil connected to the drive unit; when the tripping coil is energized, it controls the drive unit to switch to the first state, and when the closing coil is energized, it controls the drive unit to switch to the second state.

[0064] Specifically, the driving unit is a driving linkage, and it is connected to the opening coil and the closing coil. When the opening coil is energized, the opening coil drives the driving linkage to move to the first state, at which time the driving linkage drives the contacts to open; when the closing coil is energized, the closing coil drives the driving linkage to move to the second state, at which time the driving linkage drives the contacts to close.

[0065] Working principle: During the closing process of the operating mechanism (i.e., the process of switching from the second state to the first state), the drive unit drives the contacts to move. When the contact acceleration is zero and the absolute value of the velocity reaches its maximum, the contact is at the point of just closing. After reaching the point of just closing, the contact continues to move. Since the resultant force of the contact friction and the resistance of the operating mechanism buffer is opposite to the direction of contact movement, the contact velocity continuously decreases until the velocity reaches zero, thus reaching the closing position. Therefore, the closing time can be obtained by calculating the time interval between the start time of the closing current waveform and the point of just closing of the second velocity curve. The opening process is similar and will not be described in detail here.

[0066] The current sensor 2 detects the opening and closing current values ​​of the operating mechanism, enabling the processing unit 4 to obtain the start times of the opening and closing processes. The speed sensor 3 detects the first speed value of the circuit breaker contacts during the opening process and the second speed value during the closing process, allowing the processing unit 4 to obtain the exact moment of opening and closing. Therefore, the opening and closing times can be calculated. This online monitoring system for the mechanical characteristics of the switchgear allows for accurate and real-time monitoring of the circuit breaker's equipment status, improving the reliability of circuit breaker operation and power supply, and preventing safety accidents caused by untimely detection.

[0067] In a preferred embodiment, the processing unit 4 is further configured to:

[0068] Calculate the closing overtravel; the closing overtravel is the displacement from the moment of contact to the moment when the velocity value is zero in the second velocity curve.

[0069] Through the above calculations, the processing unit 4 can intuitively calculate the closing overtravel of the contacts, further realizing the monitoring of closing overtravel by the circuit breaker equipment, and further improving the reliability of circuit breaker operation and power supply.

[0070] In a preferred embodiment, the online monitoring system for the mechanical characteristics of the switchgear further includes:

[0071] Position sensor 1, the position sensor 1 is used to detect the first position signal of the circuit breaker contacts during the opening process and the second position signal during the closing process;

[0072] The processing unit 4 is further configured to:

[0073] Based on the first position signal, calculate the opening displacement during the opening process; based on the second position signal, calculate the closing displacement during the closing process.

[0074] Specifically, the position sensor 1 is connected to the input terminal of the processing unit 4.

[0075] The position of the circuit breaker contacts is detected in real time by position sensor 1, and the displacement during the opening process and the displacement during the closing process can be calculated.

[0076] In a preferred embodiment, the current sensor 2 includes a first current sensor and a second current sensor;

[0077] The first current sensor is connected to the trip coil and is used to detect the trip current value of the trip coil;

[0078] The second current sensor is connected to the closing coil and is used to detect the closing current value of the closing coil.

[0079] In a preferred embodiment, the position sensor 1 is connected to the drive unit; the speed sensor 3 is also connected to the drive unit. It should be further noted that the displacement of the drive unit is the same as the displacement of the contact.

[0080] In a preferred embodiment, the input terminal of the processing unit 4 is connected to a wireless transmission module 5, and the position sensor 1, current sensor 2, and speed sensor 3 are wirelessly connected to the input terminal of the wireless transmission module 5.

[0081] Specifically, the input terminal of the wireless transmission module 5 is connected to the GPIO C0 to C7 pins of the processing unit 4, and the output terminal of the wireless transmission module 5 is wirelessly connected to the position sensor 1, the current sensor 2, and the speed sensor 3.

[0082] In this embodiment, the wireless transmission module 5 is a GPRS communication module.

[0083] In a preferred embodiment, the output end of the processing unit 4 is connected to a touch screen 6 so as to display the calculation results of the processing unit 4 and facilitate staff to obtain monitoring results in real time.

[0084] Specifically, the GPIO A0 to A7 pins of the processing unit 4 are connected to the touch screen 6; preferably, the GPIO A0 to A7 pins of the processing unit 4 are connected to a second wireless transmission module, and the second wireless transmission module is wirelessly connected to the touch screen 6.

[0085] In a preferred embodiment, the processing unit 4, the touch screen 6, and the wireless transmission module 5 are connected to a power module 8 to supply power to them.

[0086] Specifically, such as Figure 2 As shown, the first input terminal I1, the second input terminal I2, the third input terminal I3, and the fourth input terminal I4 of the processing unit 4 are respectively connected to the power module 8; wherein, the first input terminal I1 is used to collect the mains input voltage, the second input terminal I2 is used to collect the battery voltage, the third input terminal I3 is used to collect the mains output voltage, and the fourth input terminal I4 is used to collect the mains output current.

[0087] Example 2

[0088] Based on Embodiment 1, in some embodiments, the online monitoring system for the mechanical characteristics of the switchgear further includes a filtering unit 7, which is used to filter the opening current waveform and the closing current waveform.

[0089] Furthermore, the filtering unit 7 is a Kalman filter module, which filters the opening and closing current waveforms to obtain a more accurate coil current signal.

[0090] In some embodiments, the online monitoring system for the mechanical characteristics of the switchgear further includes a first adaptive calculation unit 9, which is used to determine the start time of the tripping current waveform; the first adaptive calculation unit 9 is configured to:

[0091] s11: Obtain the tripping current waveform during multiple tripping processes;

[0092] Specifically, the tripping current waveform is a filtered current waveform;

[0093] s12: Perform wavelet decomposition on the circuit breaker current waveform to obtain the wavelet coefficients C(n) corresponding to the nth circuit breaker current waveform, where n≥1;

[0094] s13: Set the first current threshold U a (n) is the starting time of the tripping current waveform during the nth tripping process; the tripping time for each tripping process is calculated; the first current threshold U a (n) is calculated according to formula (i):

[0095]

[0096] Wherein, U1 is the first initial current threshold, and u1 is the first set step size;

[0097] s14: Starting from n=2, when the difference between the opening times of two adjacent opening processes is less than a set value and the difference of the wavelet coefficients is greater than 0, the first current threshold corresponding to the smaller value of the opening times of the two opening processes is taken as the standard value and used to determine the starting time of the opening current waveform.

[0098] Specifically, the first current threshold U a (n) is used to determine the start time of the tripping current waveform, that is, when the tripping current waveform begins to exceed the first current threshold U. a The time of (n) is taken as the starting time.

[0099] Specifically, the first initial current threshold, the first set step size, and the set value can all be set according to actual needs. For example, the first initial current threshold is 5mA, the first set step size is 1mA, and the set value is 0.01ms.

[0100] Specifically, the first adaptive calculation unit 9 is connected to the processing unit 4 and is used to determine the start time of determining the tripping current waveform.

[0101] It should be further explained that when the difference between two adjacent wavelet coefficients is equal to 0, the difference between the previous two adjacent wavelet coefficients is used to determine the value.

[0102] If it is greater than 0, then the first current threshold for this time is: the first current threshold of the previous time increased by a first set step size, that is:

[0103] U a (n)=U a (n-1)+u1;

[0104] If it is less than 0, then the first current threshold for this time is: the previous first current threshold minus the first set step size, that is:

[0105] U a (n)=U a (n-1)-u1;

[0106] To facilitate understanding by technical personnel, the specific principle is as follows:

[0107] First, the tripping current waveform is obtained during multiple tripping and closing processes; the tripping current waveform is decomposed into wavelet coefficients C(n) corresponding to the nth tripping current waveform; wavelet decomposition can decompose the tripping waveform into high-frequency signals, low-frequency signals and wavelet coefficients C(n).

[0108] Secondly, calculate the first current threshold corresponding to each closing process using formula (1); then calculate the closing time for each closing process sequentially, for example:

[0109] The first closing process yielded the first opening current waveform, at which n=1. The first initial current threshold was taken as the starting time of the opening current waveform.

[0110] The second closing process yields the second opening current waveform. At this point, n = 2. If C(n) - C(n-1) > 0, the first initial current threshold is increased by a set step; if C(n) - C(n-1) < 0, the first initial current threshold is decreased by a set step.

[0111] This process continues until the difference between the opening times of two adjacent opening processes is less than a set value and the wavelet coefficient is greater than 0. The first current threshold corresponding to the smaller value of the opening times of the two opening processes is then used as the standard value.

[0112] Finally, the obtained standard value is used as the threshold for determining the start time of the tripping current waveform.

[0113] The inventive concept of the above technical solution is as follows: based on the difference in wavelet coefficients corresponding to two tripping actions, the first initial threshold is started to search in a forward or reverse direction, that is, the step size is increased or decreased by one for each tripping action, the first current threshold is continuously updated, and the new tripping time and wavelet coefficients are calculated at the same time; when the difference in tripping time between two adjacent tripping actions is less than the set value and the difference in wavelet coefficients is greater than 0, the first current threshold corresponding to the smaller tripping time is selected as the standard value to determine the starting time of the tripping current waveform;

[0114] The above technical solution enables the initial moment of the tripping current waveform to be adaptively determined. After obtaining the final determined standard value, the final calculated tripping time can be more accurate.

[0115] In some embodiments, the online monitoring system for the mechanical characteristics of the switchgear further includes a second adaptive calculation unit 10, which is used to determine the start time of the closing current waveform; the second adaptive calculation unit 10 is configured to:

[0116] The closing current waveform of each closing process is decomposed into wavelet coefficients C(m) for each closing current waveform, where m≥1.

[0117] The second current threshold U b (m) is the starting time of the closing current waveform during the m-th closing process; the closing time of each closing process is calculated; the second current threshold U b (m) is calculated according to formula (II):

[0118]

[0119] Wherein, U2 is the second initial current threshold, and u2 is the second set step size;

[0120] Starting from m=2, when the difference between the closing times of two adjacent closing processes is less than a set value and the difference of the wavelet coefficients is greater than 0, the second current threshold corresponding to the smaller value of the closing times of the two closing processes is taken as the standard value and used to determine the starting time of the closing current waveform.

[0121] Specifically, the second current threshold U b (m) is used to determine the start time of the closing current waveform, that is, when the closing current waveform begins to exceed the second current threshold U. b The time (m) is taken as the starting time.

[0122] Specifically, the second initial current threshold, the second set step size, and the set value can all be set according to actual needs. For example, the second initial current threshold is 5mA, the second set step size is 1mA, and the set value is 0.01ms.

[0123] Specifically, the second adaptive calculation unit 10 is connected to the processing unit 4 and is used to determine the start time of determining the closing current waveform.

[0124] It should be further explained that when the difference between two adjacent wavelet coefficients is equal to 0, the difference between the previous two adjacent wavelet coefficients is used to determine the value.

[0125] If it is greater than 0, then the second current threshold is: the previous second current threshold increased by a second set step size, that is:

[0126] U b (m)=U b (m-1)+u2;

[0127] If it is less than 0, then the first current threshold for this time is: the second current threshold of the previous time minus the second set step size, that is:

[0128] U b (m)=U b (m-1)-u2;

[0129] The initial moment for adaptively determining the closing current waveform during the closing process is the same as the opening moment described above, and will not be repeated here.

[0130] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An on-line monitoring system for mechanical properties of a switchgear cabinet, said switchgear cabinet comprising a circuit breaker and a handling mechanism for controlling opening or closing of said circuit breaker in response to an external control signal, characterized in that, The circuit breaker comprises: a speed sensor (3) for detecting a first speed value of a contact of the circuit breaker during opening and a second speed value during closing; a current sensor (2) for detecting an opening current value and a closing current value of the operating mechanism; a filtering unit (7) for filtering an opening current waveform and a closing current waveform; a processing unit (4) configured to: obtain a first speed curve according to the first speed value and a second speed curve according to the second speed value; obtain the opening current waveform according to the opening current value and the closing current waveform according to the closing current value; calculate an opening time, which is a time interval between a starting time of the opening current waveform and a just-opening point in the first speed curve; the just-opening point is a time point at which the absolute value of the speed is the largest in the first speed curve; calculate a closing time, which is a time interval between a starting time of the closing current waveform and a just-closing point in the second speed curve; the just-closing point is a time point at which the absolute value of the speed is the largest in the second speed curve; a first adaptive calculation unit (9) for determining the starting time of the opening current waveform; the first adaptive calculation unit (9) is configured to: obtain the opening current waveform of the opening process for multiple times; The opening current waveform is decomposed by wavelet to obtain the wavelet coefficients corresponding to the first opening current waveform n The wavelet coefficients corresponding to the second opening current waveform , n ≥1; the time point in the opening current waveform at which the starting is greater than the first current threshold value is taken as the starting time point of the opening current waveform in the first n opening process, and the opening time of each opening process is calculated; the first current threshold According to formula (one) calculation: (I); wherein, U 1 is a first initial current threshold, u 1 is a first set step size; starting from n=2, if the difference between the opening times of the adjacent two opening processes is less than a set value and the difference between the wavelet coefficients is greater than 0, the first current threshold corresponding to the smaller opening time of the two opening processes is taken as a standard value, and is used to determine the starting time of the opening current waveform.

2. The mechanical property on-line monitoring system of switch cabinet according to claim 1, characterized in that, a second adaptive calculation unit (10) for determining the starting time of the closing current waveform; the second adaptive calculation unit (10) is configured to: The closing current waveform of each closing process is wavelet-decomposed to obtain wavelet coefficients corresponding to each closing current waveform , m ≥1; the time at which the closing current waveform starts to be greater than a second current threshold value is taken as the starting time of the closing current waveform in the first m closing process, and the closing time of each closing process is calculated; the second current threshold According to formula (two) calculation: (ii); wherein, U 2 is a second initial current threshold, u 2 is a second set step. From m =2, if the difference between the closing times of two adjacent closing processes is less than a set value and the difference between the wavelet coefficients is greater than 0, the second current threshold corresponding to the smaller closing time of the two closing processes is taken as a standard value, and is used to determine the starting time of the closing current waveform.

3. The mechanical property on-line monitoring system of switch cabinet according to claim 1, characterized in that, the processing unit (4) is further configured to: calculate a closing overtravel; the closing overtravel is a displacement between the just-closing point and a time point at which the speed value is zero in the second speed curve.

4. The mechanical property on-line monitoring system of switch cabinet according to claim 3, characterized in that, The circuit breaker further comprises: a position sensor (1) for detecting a first position signal of a contact of the circuit breaker during opening and a second position signal during closing; the processing unit (4) is further configured to: calculate an opening displacement of the opening process according to the first position signal and a closing displacement of the closing process according to the second position signal.

5. The mechanical property on-line monitoring system of switch cabinet according to claim 4, characterized in that, The operating mechanism comprises: a driving unit connected with the contact of the circuit breaker; the driving unit has a first state and a second state; in the first state, the driving unit drives the contact to open; in the second state, the driving unit drives the contact to close. A control unit has a tripping coil and a closing coil connected with the driving unit; the tripping coil is used to control the driving unit to switch to the first state when energized, and the closing coil is used to control the driving unit to switch to the second state when energized.

6. The mechanical property on-line monitoring system of switch cabinet according to claim 4, characterized in that, The current sensor (2) comprises a first current sensor and a second current sensor; The first current sensor is connected with the tripping coil and is used to detect the tripping current waveform of the tripping coil; The second current sensor is connected with the closing coil and is used to detect the closing current waveform of the closing coil.

7. The mechanical property on-line monitoring system of switch cabinet according to claim 4, characterized in that, The position sensor (1) is connected with the driving unit; the speed sensor (3) is connected with the driving unit.

8. The mechanical property on-line monitoring system of switch cabinet according to claim 4, characterized in that, The processing unit (4) is connected with a wireless transmission module (5) at the input end, and the position sensor (1), the current sensor (2) and the speed sensor (3) are wirelessly connected with the input end of the wireless transmission module (5).

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