A working method of a circuit breaker

Abstract

The present invention relates to a working method of a circuit breaker, which includes a linkage contact rod fixed to the end of the transmission shaft of the circuit breaker. On both sides of the end of the linkage contact rod, a first static contact and a second static contact are respectively provided. When the circuit breaker is closed, the transmission shaft drives the end of the linkage contact rod to only contact the first static contact; when the circuit breaker is opened, the transmission shaft drives the end of the linkage contact rod to only contact the second static contact; the first and second static contacts are connected to the I / O interface of the single-chip microcomputer through a signal processing circuit; the single-chip microcomputer judges the closing and opening states of the circuit breaker in real time according to the signals received by the I / O interface, so as to control the conduction time of the current of the permanent magnet coil of the circuit breaker and complete the intelligent control of the circuit breaker.

Description

Technical Field

[0001] The present invention belongs to the technical field of power transmission and transformation equipment condition monitoring, and relates to a working method of a circuit breaker. Background Art

[0002] In high-voltage switches of power systems, most vacuum circuit breakers adopt permanent magnet mechanism switches, which have the advantages of few mechanical parts, long service life, maintenance-free, stable and reliable, reliable operation of the mechanism, and fast opening speed.

[0003] When the permanent magnet coil of an existing circuit breaker (including a vacuum circuit breaker) is energized to work, due to the action of electromagnetic force, the drive shaft of the circuit breaker moves axially, achieving the purpose of closing and opening. However, during the closing and opening processes, there are mechanical vibrations. How to accurately and real-time judge the closing and opening positions of the circuit breaker so that the circuit breaker works in the best condition is a technical problem in this field. As Figure 1 shown, Figure 1 The waveform shown is the current state waveform detected in the permanent magnet coil when the circuit breaker switches from closing to opening. This actual waveform is mixed with a lot of stray interference or clutter caused by mechanical vibrations. If the circuit breaker switch state is judged after these clutter disappear, there will inevitably be a time delay, affecting the precise control of the circuit breaker.

[0004] Existing designs use high-cost displacement sensors or Hall sensors to achieve this goal. These methods have high costs, and during the operation of the circuit breaker, mechanical vibrations are likely to cause misjudgments. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a judging device and its working method for judging the closing and opening states of the mechanical contacts of a circuit breaker, which have high accuracy and reliability, are not prone to misjudgment, and have low costs.

[0006] To solve the above technical problem, the present invention provides a judging device for judging the closing and opening states of the mechanical contacts of a circuit breaker, including: a linkage contact rod 11 fixed to the end of the drive shaft 1 of the circuit breaker. On both sides of the end of the linkage contact rod 11, a first static contact 2 and a second static contact 3 are respectively provided. When the circuit breaker is closed, the drive shaft 1 drives the end of the linkage contact rod 11 to only contact the first static contact 2; when the circuit breaker is opened, the drive shaft drives the end of the linkage contact rod 11 to only contact the second static contact 3; the first and second static contacts are connected to the I / O interface of the single-chip microcomputer through a signal processing circuit (preferably an optoelectronic isolation circuit or a magnetic coupling isolation or an A / D conversion circuit); the single-chip microcomputer judges the closing and opening states of the circuit breaker in real time according to the signals received by the I / O interface. Once it judges that the circuit breaker is in place for opening or closing, the single-chip microcomputer cuts off the working current of the permanent magnet coil of the circuit breaker, completing the intelligent control of the circuit breaker.

[0007] The working method of the single-chip microcomputer includes: establishing a detection window with a fixed time interval in the software space. This time window makes full use of the precise timer in the MCU to test the opening and closing states of the circuit breaker every 0.5 ms, and sequentially record 0 and 1 representing the opening and closing states respectively in the 32-bit file register as shown in Figure 4 The 32-bit file register corresponds to the recorded values of the time window, and a total of 32 equally spaced 0 and 1 states are recorded, with a total window of 16 ms; as time goes by, following the principle of first in first out, the old recorded values are continuously removed and the latest values are recorded. After each new value is recorded,

[0008] Formula 1:

[0009] Where: CNT is the count value, Bt is the value of each bit in the 32-bit file register, and t is the time interval of 0.5 ms;

[0010] Formula 2: Closing threshold H TH = k H .CNT

[0011] Where, k H is the closing threshold coefficient 0.75 (obtained by averaging experimental data);

[0012] Formula 3: Tripping threshold F TH = k T .CNT

[0013] Where, k T is the tripping threshold coefficient 0.25 (obtained by averaging experimental data);

[0014] According to the above formula 1, count the number of 1 states. When the closing threshold H TH is greater than the preset closing threshold, it is judged as the closing state; when the tripping threshold F TH is less than the preset tripping threshold, it is judged as the tripping state; this method can eliminate occasional interference and accurately distinguish mechanical jitter interference, and accurately judge the point of change in the opening and closing positions of the circuit breaker.

[0015] A working method of a circuit breaker applying the above judgment device includes: when the single-chip microcomputer receives an opening or closing control signal, it sends a pulse-width adjustable signal to the IGBT drive circuit through the PWM module inside the single-chip microcomputer to drive the permanent magnet coil of the circuit breaker to work, and then controls the displacement of the transmission shaft of the circuit breaker to implement the opening or closing action of the circuit breaker; at the same time, the single-chip microcomputer continuously judges the opening and closing states of the circuit breaker according to the signals received by the I / O interface. Once it is detected that the circuit breaker is in place for opening or closing, the single-chip microcomputer cuts off the working current of the permanent magnet coil of the circuit breaker.

[0016] The technical effect of the present invention: The sampling circuit breaker mechanism in the judgment device of the present invention has its own linkage auxiliary contacts. To realize the judgment of the closing and opening positions of the high-voltage switch, the cost is lower than that of the prior art, the judgment accuracy and reliability are higher, and it is not easy to make a misjudgment. The present invention uses the linkage auxiliary contacts of the mechanism to judge the closing and opening positions of the circuit breaker in real time, so as to accurately and timely cut off the working current of the permanent magnetic coil. The single-chip microcomputer receives the closing or opening state signal, and sends a pulse width adjustable signal to the IGBT drive circuit through the internal PWM module of the single-chip microcomputer to drive the permanent magnetic coil of the circuit breaker to work. At the same time, the single-chip microcomputer detects the closing and opening positions of the circuit breaker in real time by the linkage auxiliary contacts of the mechanism. Once the circuit breaker is in place, the single-chip microcomputer cuts off the working current of the coil to prevent the coil from being energized for a long time and causing damage. The working process of the present invention can greatly avoid the influence of ripples and burrs in the judgment process, and improve the accuracy of closing and opening judgment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to make the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0018] Figure 1 It is a current waveform diagram in the permanent magnetic coil when the existing circuit breaker changes from closing to opening;

[0019] Figure 2 It is a structural schematic diagram of a device for judging the closing and opening states of mechanical contacts of a circuit breaker according to the present invention;

[0020] Figure 3 It is a schematic diagram of the time window from closing to opening of the circuit breaker of the present invention;

[0021] Figure 4 It is a schematic diagram of a 32-bit file register of the present invention recording status signals at equal intervals in a first-in-first-out manner;

[0022] Figure 5 is a circuit principle block diagram of the judgment device of the present invention;

[0023] Figure 6 It is a circuit schematic diagram of the signal processing circuit of the present invention. DETAILED DESCRIPTION

[0024] like Figures 1-6, the judging device for the closing and opening states of the mechanical contacts of the circuit breaker in this embodiment includes: a linkage contact rod 11 fixed to the end of the transmission shaft 1 of the circuit breaker. On both sides of the end of the linkage contact rod 11, a first static contact 2 and a second static contact 3 are respectively provided. When the circuit breaker is closed, the transmission shaft drives the end of the linkage contact rod 11 to only contact the first static contact 2, and a low-voltage DC circuit is formed; when the circuit breaker is opened, the transmission shaft drives the end of the linkage contact rod 11 to only contact the second static contact 3, and another low-voltage DC circuit is formed; the first and second static contacts are connected to the I / O interface of the single-chip microcomputer through a signal processing circuit (preferably an optoelectronic isolation circuit or a magnetic coupling isolation or A / D conversion circuit); the single-chip microcomputer judges the closing and opening states of the circuit breaker in real time according to the signals received by the I / O interface, so as to control the conduction time of the current of the permanent magnet coil L of the circuit breaker and complete the intelligent control of the circuit breaker.

[0025] The judging method for the closing and opening states of the mechanical contacts of the circuit breaker, including the working method of the single-chip microcomputer, specifically includes: establishing a detection window with a fixed time interval in the software space of the single-chip microcomputer. This time window makes full use of the precise timer in the MCU. Every 0.5 ms, the closing and opening states of the circuit breaker are tested, and the 0 and 1 representing the opening and closing states respectively are sequentially recorded in the Figure 4 shown 32-bit file register. The 32-bit file register corresponds to the recorded values of the time window, and a total of 32 equally spaced 0 and 1 states are recorded, with a total window of 16 ms; as time goes by, this window adopts the principle of first in first out, continuously removes the old recorded values, and records the latest values. After each new value is recorded,

[0026] Formula 1:

[0027] where: CNT is the count value, Bt is the value of each bit in the 32-bit file register, and t is the time interval of 0.5 ms;

[0028] Formula 2: Closing threshold H TH =k H .CNT

[0029] where k H is the closing threshold coefficient 0.75 (obtained by averaging experimental data);

[0030] Formula 3: Opening threshold F TH =k T .CNT

[0031] where k T is the opening threshold coefficient 0.25 (obtained by averaging experimental data);

[0032] According to the above formula 1, the number of states 1 is counted. When the closing threshold H TH When it is greater than the preset closing threshold, it is judged as the closing state; when the opening threshold F TH When it is less than the preset opening threshold, it is judged to be in the opening state; this method can eliminate occasional interference, accurately distinguish mechanical jitter interference, and accurately determine the point where the circuit breaker opening and closing position changes.

[0033] As an optional implementation, the file register may also use 24, 48, 64 or 128 bits, and the interval of 0.5 ms may be adjusted accordingly. The single chip microcomputer is preferably an M4, M5, M6 or M7 single chip microcomputer.

[0034] like Figure 5 The present invention uses the linkage auxiliary contacts of the mechanism to judge the closing and opening status of the circuit breaker in real time, so as to accurately and timely cut off the working current of the permanent magnet coil. The specific working process is: when the single-chip microcomputer receives the closing or opening control signal, the pulse width adjustable signal is sent to the IGBT drive circuit through the internal PWM module of the single-chip microcomputer to drive the permanent magnet coil of the circuit breaker to work, and then control the displacement of the transmission shaft to implement the closing or opening action; at the same time, the single-chip microcomputer judges the closing and opening status of the circuit breaker in real time according to the signal received by the I / O interface. Once it is judged that the circuit breaker is opened or closed, the single-chip microcomputer cuts off the working current of the permanent magnet coil to prevent the permanent magnet coil from being energized for a long time and causing damage. The working process of the present invention can avoid the influence of ripples and burrs in the judgment process to a great extent, and improve the accuracy of closing and opening judgment.

[0035] like Figure 6 , the signal processing circuit: a low-voltage DC power supply is applied to the loop where the end of the linkage touch rod is located, and the signal flows through resistors R1 and R2 to turn the optocoupler on or off, generating a digital signal level of 0 or 1, which is sent to the I / O interface of the single-chip microcomputer. The single-chip microcomputer samples the circuit breaker closing and opening signals at equal intervals in real time, and removes mechanical jitter and random interference signals through the window algorithm of the present invention to achieve accurate judgment. In the figure, C1 is a hardware filter, VD1 is a high-voltage interference clamp circuit, and R3 is an optocoupler current limiting protection resistor.

[0036] Obviously, the above embodiments are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. However, these obvious changes or modifications derived from the spirit of the present invention are still within the scope of protection of the present invention.

Claims

1. A working method of a circuit breaker, the circuit breaker comprising a judging device for the closing and opening states of the closing and opening mechanical contacts of the circuit breaker, characterized in that, The judging device includes a linkage contact rod fixed to the end of the transmission shaft of the circuit breaker, and a first static contact and a second static contact are respectively arranged on both sides of the end of the linkage contact rod; When the circuit breaker is closed, the transmission shaft drives the end of the linkage contact rod to only contact the first static contact; when the circuit breaker is opened, the transmission shaft drives the end of the linkage contact rod to only contact the second static contact; the first static contact and the second static contact are connected to the I / O interface of the single-chip microcomputer through a signal processing circuit; the single-chip microcomputer judges the closing and opening states of the circuit breaker in real time according to the signals received by the I / O interface, and once it judges that the circuit breaker is opened or closed in place, the single-chip microcomputer cuts off the working current of the permanent magnet coil of the circuit breaker; The working method of the circuit breaker includes: when the single-chip microcomputer receives a closing or opening control signal, it sends a pulse width adjustable signal to the IGBT drive circuit through the PWM module inside the single-chip microcomputer to drive the permanent magnet coil of the circuit breaker to work, thereby controlling the displacement of the transmission shaft of the circuit breaker to implement the closing or opening action of the circuit breaker; at the same time, the single-chip microcomputer judges the closing and opening states of the circuit breaker in real time according to the signals received by the I / O interface, and once it measures that the circuit breaker is closed or opened in place, the single-chip microcomputer cuts off the working current of the permanent magnet coil of the circuit breaker; The working method of the judging device includes: establishing a detection time window with a fixed time interval in the software space of the single-chip microcomputer. This time window makes full use of the precise timer in the MCU, tests the opening and closing states of the circuit breaker every 0.5 ms, and sequentially records 0 and 1 representing the opening and closing states in a 32-bit file register. The 32-bit file register corresponds to the recorded values of the time window, and a total of 32 equally spaced 0 and 1 states are recorded, with a total window of 16 ms; as time goes by, this 16-ms window removes the old recorded values and records the latest values according to the first-in, first-out principle. After each new value is recorded, Formula 1: CNT= ; Where: CNT is the count value, and B t is the value of each bit in a 32-bit file register, and t is the time interval of 0.5 ms; Formula 2: Closing Threshold H TH = k H * CNT where k H is the closing threshold coefficient 0.75, obtained by averaging experimental data; Formula 3: Opening Threshold F TH = k T * CNT Among them, k T is the opening threshold coefficient 0.25, obtained by averaging experimental data; Count the number of 1 states according to the above formula 1. When the closing threshold H TH is greater than the preset closing threshold, it is judged as the closing state; when the opening threshold F TH is less than the preset opening threshold, it is judged as the opening state.

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