Rapid mechanical switch overtravel measurement method based on high-speed camera image processing

Abstract

The invention discloses a rapid mechanical switch overtravel measurement method based on high-speed camera image processing. According to the invention, a signal sensor is used for recording a trigger signal for a high-speed camera to accurately obtain a breaker contact action rigid separation point, and a complete mechanical switch motion process is obtained by setting a high-speed camera advanced recording function; the time for completing the overtravel of the switch is obtained by calculating the frame difference between the light-emitting moment of the light-emitting diode and the just-opening signal triggering moment, so that data such as the total travel, the opening range and the overtravel of the switch can be accurately obtained. The research on the switch overtravel is of great significance to guarantee the safety, reliability and service life of the mechanical switch.

Description

Technical Field

[0001] A fast mechanical switch overtravel measurement method based on high-speed camera image processing relates to the technical field of DC circuit breaker disconnection. Background Art

[0002] Circuit breakers are one of the most important high-voltage switchgear in power systems. As an important component, the reliability of mechanical switches directly affects the safe and stable operation of power grids. With the vigorous construction of smart grids, in order to avoid unnecessary losses caused by mechanical failures of switches, the mechanical characteristics detection of switches becomes more important.

[0003] The contact travel-time characteristic curve of the switch is an important representation of its health status. In order to obtain the contact travel curve, it is necessary to measure the total travel and overtravel of the switch. The previous method is to install a displacement sensor on the circuit breaker body. At present, the circuit breaker contact travel displacement measurement sensors mainly include linear displacement sensors, differential transformer displacement sensors, incremental rotary photoelectric encoders, etc. Among them, the linear displacement sensor is installed at the lower end of the insulating pull rod to directly collect the displacement signal of the moving contact, but it is difficult to install, has poor accuracy, low anti-interference ability, and also destroys the original structure of the circuit breaker, affecting the insulation performance; the differential transformer displacement sensor is installed on the main shaft of the circuit breaker. The displacement of the contact movement changes the distribution of the spatial magnetic field, so that the secondary winding induces different electromotive forces. The contact travel displacement is measured by measuring the output voltage, but the sensor is large and not suitable for medium-voltage circuit breakers; the incremental rotary photoelectric encoder is installed on the main shaft of the circuit breaker. It not only takes up less space, but also does not affect the insulation performance of the circuit breaker. It has strong anti-interference ability, but the output digital signal cannot intuitively reflect the circuit breaker travel characteristics. The corresponding measurement circuit needs to be designed for measurement. Summary of the invention

[0004] In view of the above problems and technical requirements, the present invention proposes a fast mechanical switch overtravel measurement method based on high-speed camera image processing. The fast mechanical switch overtravel measurement method based on high-speed camera image processing of the present invention can intuitively reflect the mechanical travel characteristics of the switch, including total travel, contact travel and overtravel. The purpose of testing the performance of the switch through such a method of testing its mechanical performance is to eliminate hidden dangers as early as possible through detection means to avoid the occurrence of malignant accidents, which is the key to ensuring the safe and reliable operation of the switch system and stable operation.

[0005] The technical solution of the present invention is as follows: A fast mechanical switch overtravel measurement method based on high-speed camera image processing comprises the following steps: Step 1: The high-speed camera is in a recording state but no image caching is performed. The recording object is a mechanical switch repulsion disk. The repulsion disk of the mechanical switch is in a closed position, i.e., an initial state of an opening operation, and the opening energy storage capacitor is charged. Step 2, using thyristor to control the opening operation, the opening energy storage capacitor is discharged, and the light-emitting diode lights up to indicate the opening control signal moment; Step 3, the opening coil generates a pulse current to generate an electromagnetic repulsive force on the repulsion disk; Step 4: When the mechanical switch is opened and the overtravel is completed, the two moving and static contacts of the mechanical switch are separated in the initial state. At this time, the electrical connection is disconnected, and the edge of the line state change triggers the just-opening signal, which is transmitted to the high-speed camera to achieve the high-speed camera cache condition for image cache; Step 5, by calculating the setting frame difference between the opening control signal moment of the light-emitting diode and the buffer image of the high-speed camera just after the opening signal, the overtravel completion time of the mechanical switch is calculated to obtain the total stroke, opening distance and overtravel of the circuit breaker contact.

[0006] The beneficial effects of the present invention are as follows: (1) The present invention can intuitively reflect the mechanical travel characteristics of the switch, including the total travel, contact travel and overtravel, avoiding the influence of traditional displacement sensors on the results due to factors such as difficult installation, poor accuracy and low anti-interference ability; (2) The present invention detects the mechanical properties of the mechanical switch in the DC circuit breaker to eliminate hidden dangers as early as possible and thus avoid the occurrence of serious accidents. This is the key to ensuring the safe and reliable operation of the switch and the stable operation of the system.

[0007] (3) The present invention uses a signal sensor to accurately obtain the contact action just-opening point of the circuit breaker by recording the trigger signal with a high-speed camera, and obtains the complete mechanical switch movement process by setting the high-speed camera to record in advance. By calculating the frame difference between the light-emitting diode light-emitting moment and the trigger moment of the just-opening signal, the time when the switch completes the overtravel can be obtained, and the total switch travel, opening distance and overtravel data can be accurately obtained. Studying the switch overtravel is of great significance to ensuring the safety, reliability and life of the mechanical switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A diagram of a mechanical switch component of the present invention; Figure 2 It is a layout diagram of the equipment of the present invention; Figure 3 This is the target image for image detection according to the present invention.

[0009] In the figure, the reference numerals are: 1-static contact, 2-vacuum interrupter, 3-moving contact, 4-first busbar, 5-porcelain sleeve, 6-bellows, 7-flexible connection, 8-upper pull rod, 9-insulator, 10-closing holding permanent magnet, 11-armature, 12-opening holding permanent magnet, 13-opening coil, 14-repulsion disk, 15-closing coil, 16-repulsion mechanism, 17-second busbar, 18-disc spring, 19-lower pull rod, 20-opening control thyristor, 21-closing control thyristor, 22-opening energy storage capacitor, 23-closing energy storage capacitor, 24-charging power supply, 25-isolation transformer, 26-light emitting diode, 1-1-mechanical switch, 1-2-high-speed camera, 1-3-computer. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above-mentioned purpose, the present invention adopts the following technical scheme.

[0011] like Figure 1As shown, the mechanical switch 1-1 is composed of a vacuum interrupter 2 and a repulsive mechanism 16. A moving contact 3 and a stationary contact 1 are arranged in the vacuum interrupter 2, and the moving contact 3 and the stationary contact 1 realize the closing and opening operations. The upper end of the vacuum interrupter 2 is connected to the first busbar 4, and the outer side of the vacuum interrupter 2 is surrounded by a porcelain sleeve 5 for insulation. The vacuum interrupter 2 is also provided with a bellows 6, which is used to ensure that the moving contact 3 moves within a certain range and maintains a high vacuum function for a long time. The repulsion mechanism 16 provides the repulsion and attraction required for the moving contact 3 and the static contact 1 to open and close the switch, wherein the repulsion disk 14, the opening coil 13 and the closing coil 15 provide repulsion and attraction to each other, the closing coil 15 acts on the closing, and the closing maintains the magnetic force generated by the combination of the permanent magnet 10 and the armature 11. The two ends of the upper pull rod 8 are respectively connected to the moving contact 3 and the upper end of the insulator 9. A disc spring 18 is placed between the upper end of the insulator 9 and the upper pull rod 8. The disc spring 18 forms an over-travel buffering effect. The moving contact 3 and the static contact 1 are separated until the arc is extinguished to complete the opening operation. The lower end of the insulator 9 is directly connected to the lower pull rod 19. The lower pull rod 19 is tightly connected with the armature 11 and the repulsion disk 14 and keeps the same motion state. The lower pull rod 19 and the armature 11 overcome the reaction force of the disc spring 18 and the gravity of the moving parts, and prevent the electric force or mechanical vibration caused by the short-circuit fault current from causing the wrong opening, and provide effective holding force when the closing position is maintained and maintain the initial state of the opening operation. The repulsion disk 14 generates a current in the opposite direction of the opening coil 13 under the influence of the eddy current effect, thereby generating an electromagnetic repulsion force, so that the repulsion disk 14 drives the moving parts connected to it to move in the opening direction, and the other parts are fixed and do not constitute a connection moving part. The first busbar 4 and the second busbar 17 are connected with the soft connection 7, and the soft connection 7 can be a wire. The opening holding permanent magnet 12 has the function of maintaining the opening state. The opening coil 13 is used for opening. The opening energy storage circuit provides the opening current. The opening energy storage circuit includes the opening control thyristor 20, the closing control thyristor 21, the opening energy storage capacitor 22, the closing energy storage capacitor 23, the charging power supply 24, and the isolation transformer 25.

[0012] The present invention proposes a fast mechanical switch overtravel measurement method based on high-speed camera image processing. The high-speed camera 1-2 collects the image of the mechanical switch 1-1 and transmits it to the computer 1-3. The specific implementation steps of the present invention are as follows: At the initial moment, the repulsion disk 14 and the opening coil 13 of the mechanical switch 1-1 are in the closed position, and the disc spring 18 is placed at the connection part between the insulator 9 and the upper pull rod 8, and the magnetic force generated by the combination of the permanent magnet 10 and the armature 11 to keep the closing switch keeps the moving part of the repulsion mechanism 16 balanced. The moving part includes the moving contact 3, the upper pull rod 8, the insulator 9, the armature 11, the repulsion disk 14, and the lower pull rod 19. The object of the high-speed camera 1-2 is the repulsion disk 14 in the repulsion mechanism 16, which is in the shooting and non-recording state at this time, as shown in 2.

[0013] When the opening operation of the mechanical switch 1-1 is performed, the opening control thyristor 20 controls the operation so that the opening energy storage capacitor 22 discharges the opening coil 13 and generates a pulse current, which generates an eddy current in the repulsion disk 14; the repulsion disk 14 generates a current in the opposite direction to the opening coil 13 under the influence of the eddy current effect, thereby generating an electromagnetic repulsive force, so that the repulsion disk 14 drives the moving parts connected to it to move in the opening direction.

[0014] When the repulsion disk 14 continues to move in the opening direction and the disc spring 8 ends its overtravel and pulls the moving contact 3 to move, the mechanical switch 1-1 opens and completes the overtravel. This is recorded as the initial state of the moving and static contacts of the mechanical switch 1-1 being separated. At this time, the electrical connection is disconnected, and the edge of the line state change triggers the just-opening signal. The high-speed camera 1-2 receives the just-opening signal to trigger the cache. The cache point of the high-speed camera 1-2 is the 1000 frames of image data before the just-opening, including the opening signal triggering the diode to turn on and the moving image of the repulsion disk 14, with a total duration of 3000 frames.

[0015] The opening distance of the mechanical switch 1-1 can be obtained by calculating the opening displacement of the repulsion disk 14, i.e., the total switch travel, by using the opening image of the mechanical switch 1-1 cached by the high-speed camera 1-2, and then subtracting the displacement during the overtravel time. Therefore, the overtravel of the switch can be accurately measured by the method of the present invention.

[0016] A light emitting diode and a current limiting resistor series branch are installed at the gate of the thyristor in the opening control circuit of the mechanical switch 1-1. The light display is used to obtain the information of the time when the opening instruction is issued. Opening means that the opening energy storage circuit receives the opening signal of the control system and is turned on.

[0017] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A fast mechanical switch overtravel measurement method based on high-speed camera image processing, characterized in that: The steps include: Step 1: The high-speed camera is in a recording state but no image caching is performed. The recording object is a mechanical switch repulsion disk. The repulsion disk of the mechanical switch is in a closed position, i.e., an initial state of an opening operation, and the opening energy storage capacitor is charged. Step 2, using thyristor to control the opening operation, the opening energy storage capacitor is discharged, and the light-emitting diode lights up to indicate the opening control signal moment; Step 3, the opening coil generates a pulse current to generate an electromagnetic repulsive force on the repulsion disk; Step 4: When the mechanical switch is opened and the overtravel is completed, the two moving and static contacts of the mechanical switch are separated in the initial state. At this time, the electrical connection is disconnected, and the edge of the line state change triggers the just-opening signal, which is transmitted to the high-speed camera to achieve the high-speed camera cache condition for image cache; Step 5, by calculating the setting frame difference between the opening control signal moment of the light-emitting diode and the buffer image of the high-speed camera just after the opening signal, the overtravel completion time of the mechanical switch is calculated to obtain the total stroke, opening distance and overtravel of the circuit breaker contact.

2. The method for measuring the overtravel of a fast mechanical switch based on high-speed camera image processing according to claim 1, characterized in that: In step 1, the opening process of the high-speed mechanical switch is as follows: at the initial moment, the repulsion disk and the excitation coil are in the closed position, disc springs are placed at the connection between the insulator and the upper pull rod, and the total stroke of the switch is obtained by shooting the moving image of the repulsion disk with a high-speed camera. The compression amount of the disc spring is the overstroke, and the cache condition is that the high-speed camera obtains the just-opened signal of the mechanical switch.

3. The method for measuring the overtravel of a fast mechanical switch based on high-speed camera image processing according to claim 1, characterized in that: In step 2, a light-emitting diode and a current-limiting resistor series branch are installed at the gate of the thyristor of the mechanical switch opening control circuit. The light-emitting display is used to obtain the information of the time when the opening instruction is issued. Opening means that the opening energy storage circuit receives the opening signal of the control system and is turned on.

4. The method for measuring the overtravel of a fast mechanical switch based on high-speed camera image processing according to claim 1, characterized in that: The cache image setting described in step 4 is a process of setting the cache image to the first 1000 frames of the just-divided signal, with a total duration of 3000 frames.

5. The method for measuring the overtravel of a fast mechanical switch based on high-speed camera image processing according to claim 1, characterized in that: In step 5, the opening displacement of the repulsion disk, i.e., the total switch stroke, is calculated through the opening image of the mechanical switch cached by the high-speed camera, and then the displacement during the overtravel time is subtracted to obtain the opening distance of the mechanical switch.

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