A method for evaluating the performance of a high-voltage circuit breaker

Abstract

The present invention discloses a method for evaluating the performance of a high-voltage circuit breaker, comprising the following steps: Step S1, collecting current and vibration signals during the opening and closing processes of the high-voltage circuit breaker in a normal state; Step S2, extracting the extreme point t0 of the current signal; Step S3, calculating the short-time work entropy ratio of the vibration signal; Step S4, performing threshold processing on the short-time work entropy ratio of the vibration signal to obtain vibration event action time parameters t1, t2, and t3; Step S5, calculating the time difference based on the vibration event action time parameters and the current extreme point time; Step S6, collecting the current and vibration signals of the high-voltage circuit breaker in other operating states, extracting the time difference and comparing it with the normal state, and evaluating the performance of the high-voltage circuit breaker according to the error. The present invention can improve the deficiencies of the prior art, can detect the performance of the high-voltage circuit breaker online, is convenient and fast, and ensures power supply reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment fault diagnosis, and in particular to a method for evaluating the performance of a high-voltage circuit breaker. Background Art

[0002] High-voltage circuit breakers play an important role in protecting and controlling power systems. Conducting performance detection and evaluation of high-voltage circuit breakers is of great significance for improving power supply reliability and ensuring people's livelihood. For the performance detection of high-voltage circuit breakers, traditional testing methods are off-line detections. Such detections require powering off the circuit breaker and using equipment such as high-voltage switch testers to test the closing and opening coil currents and the moving contact stroke curves, and evaluating the performance of the high-voltage circuit breaker based on the test results. With the development of technology, on-line detection methods for high-voltage circuit breakers have been developed. Currently, existing on-line monitoring methods for the health status of high-voltage circuit breakers rely heavily on the construction of a sample library. Needed A large number of test samples are required. However, in the actual application process, due to various conditions, it is impossible to collect sufficient test data to construct an ideal sample library. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for evaluating the performance of a high-voltage circuit breaker, which can solve the deficiencies of the existing technology, can on-line detect the performance of the high-voltage circuit breaker, is convenient and fast, and ensures power supply reliability.

[0004] To solve the above technical problems, the technical solutions adopted by the present invention are as follows.

[0005] A method for evaluating the performance of a high-voltage circuit breaker includes the following steps:

[0006] Step S1: Collect the current and vibration signals during the opening and closing processes of the high-voltage circuit breaker in the normal state;

[0007] Step S2: Extract the extreme point t0 of the current signal;

[0008] Step S3: Calculate the short-time work entropy ratio of the vibration signal;

[0009] Step S4: Perform threshold processing on the short-time work entropy ratio of the vibration signal to obtain the vibration event action time parameters t1, t2, and t3;

[0010] Step S5: Calculate the time difference according to the vibration event action time parameter and the current extreme point time;

[0011] Step S6: Collect the current and vibration signals of the high-voltage circuit breaker in other operating states, extract the time difference and compare it with the normal state, and evaluate the performance of the high-voltage circuit breaker according to the error.

[0012] Preferably, in step S1, the Hall sensor and the acceleration sensor are used to collect the current and vibration signals during the opening and closing processes of the high-voltage circuit breaker respectively. The Hall sensor passes through the opening and closing coils, and the acceleration sensor is installed on the main body of the operating mechanism of the circuit breaker.

[0013] Preferably, in step S3, the vibration signal is processed by frame division. The sliding window method is used to divide the vibration signal into multiple overlapping frame numerical signals. For the i-th frame signal x i (m) obtained after the windowing and frame division processing, after performing the fast Fourier transform, f k , Y i (k) is the corresponding energy spectrum, and then by calculating the spectral probability density function, short-time spectral entropy, and short-time power, the short-time work entropy ratio is finally obtained.

[0014] Preferably, in step S3, the frame numerical signal is y i (n) = ω(n) * x((i - 1) * inc + n), where x(i) is the original vibration signal, n = 1, 2,... L, i = 1, 2,... fn, L is the frame length, inc is the frame shift length, fn is the total number of frames after frame division, and ω(n) is the rectangular window function.

[0015] Preferably, in step S3,

[0016] Spectral probability density function

[0017] Short-time spectral entropy

[0018] Short-time power

[0019] The short-time work entropy ratio PEF(i) = ln(1 + |PE i / H i |).

[0020] Preferably, in step S4, the calculation process of the threshold Det is as follows:

[0021] Me = max{PEF(i)}

[0022]

[0023] Det = a × (Me - eth) + eth;

[0024] where a is the threshold coefficient; comparing the calculated short-time work entropy ratio with the threshold, the moment exceeding the threshold is the moment when the operating mechanism of the circuit breaker acts.

[0025] Preferably, in step S5, the time difference is as follows:

[0026] Δt1 = t1 - t0

[0027] Δt2 = t2 - t0

[0028] Δt3 = t3 - t1。

[0029] Preferably, in step S6, the specific error calculation steps are as follows,

[0030]

[0031]

[0032]

[0033] Preferably, in step S6, the fault judgment criterion for the high - voltage circuit breaker is as follows,

[0034] When Y1 ≥ 10%, it is determined that the coil is burned out or jammed;

[0035] When Y2 ≥ 10%, it is determined that the lubrication of the operating mechanism is poor;

[0036] When , it is determined that the closing spring is fatigued;

[0037] When , it is determined that the opening spring is fatigued.

[0038] The beneficial effects brought by adopting the above - mentioned technical solution are as follows: The present invention provides a method for extracting parameters from current and vibration signals to evaluate the performance of a high - voltage circuit breaker. After collecting the current of the closing and opening coils of the high - voltage circuit breaker and the vibration signal of the operating mechanism, the occurrence time points of the current signals are extracted, and then the short - time power entropy ratio is used to process the vibration signal to obtain the vibration event time parameter. By comparing with the time difference △t in the normal state, the performance status of the high - voltage circuit breaker can be judged. Compared with other existing pattern recognition algorithms, the present invention uniquely designs the calculation methods of short - time power and short - time power entropy ratio, as well as the error calculation and judgment methods. It does not require a large number of test samples. Only by collecting a set of current and vibration signals in the normal state as a standard can the performance of the high - voltage circuit breaker be judged, which greatly improves the performance evaluation efficiency and solves the problem that the existing technology cannot be popularized due to the difficulty of obtaining a large number of test samples. The proposed method has the characteristics of fast calculation and convenient popularization and application. Brief Description of the Drawings

[0039] Figure 1 is the overall flowchart of the present invention.

[0040] Figure 2 is the time - parameter extraction result of the embodiment of the present invention. Detailed Embodiment

[0041] Reference Figure 1 , a specific embodiment of the present invention includes the following steps:

[0042] Step S1: Collect the current and vibration signals during the opening and closing processes of the high-voltage circuit breaker through a Hall sensor and an acceleration sensor respectively. The Hall sensor passes through the opening and closing coils, and the acceleration sensor is installed on the main body of the operating mechanism of the circuit breaker;

[0043] Step S2: Extract the extreme point t0 of the current signal;

[0044] Step S3: Calculate the short-time work entropy ratio of the vibration signal; specifically,

[0045] Perform frame segmentation on the vibration signal, and use the sliding window method to divide the vibration signal into multiple overlapping frame numerical signals. The frame numerical signal is y i (n) = ω(n) * x((i - 1) * inc + n), where x(i) is the original vibration signal, n = 1, 2,... L, i = 1, 2,... fn, L is the frame length, inc is the frame shift length, fn is the total number of frames after frame segmentation, and ω(n) is the rectangular window function,

[0046] For the i-th frame signal x i (m) obtained after windowed frame segmentation, after performing the fast Fourier transform, f k , Y i (k) is the corresponding energy spectrum, and then by calculating the spectral probability density function, short-time spectral entropy, and short-time power, finally obtain the short-time work entropy ratio;

[0047] Spectral probability density function

[0048] Short-time spectral entropy

[0049] Short-time power

[0050] Short-time work entropy ratio PEF(i) = ln(1 + |PE i / H i |);

[0051] Step S4: Perform threshold processing on the short-time work entropy ratio of the vibration signal to obtain the vibration event action time parameters t1, t2, t3; the calculation process of the threshold Det is,

[0052] Me = max{PEF(i)}

[0053]

[0054] Det = a × (Me - eth) + eth;

[0055] where a is the threshold coefficient; compare the calculated short-time work entropy ratio with the threshold, and the moment exceeding the threshold is the moment when the breaker operating mechanism acts.

[0056] Step S5: Calculate the time difference based on the vibration event action time parameter and the current extreme point time; the time difference is

[0057] Δt1 = t1 - t0

[0058] Δt2 = t2 - t0

[0059] Δt3 = t3 - t1;

[0060] Step S6: Collect the current and vibration signals of the high-voltage breaker in other operating states, extract the time difference and compare it with the normal state, and evaluate the performance of the high-voltage breaker according to the error.

[0061] The specific calculation steps of the error are as follows

[0062]

[0063]

[0064]

[0065] The fault judgment standard of the high-voltage breaker is

[0066] When Y1 ≥ 10%, it is determined that the coil is burned or jammed;

[0067] When Y2 ≥ 10%, it is determined that the lubrication of the operating mechanism is poor;

[0068] When it is determined that the closing spring is fatigued;

[0069] When it is determined that the opening spring is fatigued.

[0070] Referring to Figure 2 , in this embodiment, the experimental object is a high-voltage breaker equipped with a spring operating mechanism. The current and vibration signals of the high-voltage breaker in the normal state and the state of closing spring fatigue are collected respectively. The sampling frequency is set to 100K, and the sampling time is set to 300ms.

[0071] When the Hall sensor detects a signal, it automatically triggers the signal acquisition system to start collecting current signals and vibration signals. After the signal collection is completed, the occurrence time t0 of the current signal is extracted as the starting point, and the vibration signal is framed using the sliding window method. The window function uses the rectangular window function. Calculate the short-time power entropy ratio of each frame of the signal, and compare the calculated short-time power entropy ratio with the threshold. The moments exceeding the threshold are the action occurrence times t1, t2, and t3 of the circuit breaker operating mechanism. Based on this, the time differences between the action time parameters and the current extreme points can be calculated. Under normal conditions, Δt1, Δt2, and Δt3 are 37.4 ms, 47.0 ms, and 59.1 ms respectively. Under the fatigue state of the closing spring, the calculated error Y results are as follows:

[0072]

[0073] After the closing spring becomes fatigued, the stored energy decreases, and the movement time of the operating mechanism is correspondingly extended, resulting in an increase in the error Y3, indicating a decline in the performance of the high-voltage circuit breaker. In addition, Y1, Y2, and Y3 can be used to judge faults such as burnout of the closing and opening coils of the high-voltage circuit breaker, jamming of the operating mechanism, poor lubrication, and spring fatigue, corresponding to different errors, which need to be determined according to the structural type of the high-voltage circuit breaker.

[0074] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention.

[0075] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for evaluating the performance of a high-voltage circuit breaker, characterized in that It includes the following steps: Step S1: Collect the current and vibration signals during the opening and closing processes of the high-voltage circuit breaker in the normal state; Step S2: Extract the extreme point t0 of the current signal; Step S3: Calculate the short-time work entropy ratio of the vibration signal; Step S4: Perform threshold processing on the short-time work entropy ratio of the vibration signal to obtain the vibration event action time parameters t1, t2, and t3; Step S5: Calculate the time difference based on the vibration event action time parameter and the current extreme point time; Step S6: Collect the current and vibration signals of the high-voltage circuit breaker in other operating states, extract the time difference and compare it with the normal state, and evaluate the performance of the high-voltage circuit breaker according to the error; In step S3, frame processing is performed on the vibration signal. The vibration signal is divided into multiple overlapping frame numerical signals by using the sliding window method. For the i-th frame signal x i (m) obtained after the windowing and framing process, after performing the fast Fourier transform, f k is obtained, and Y i (k) is the corresponding energy spectrum. Then, by calculating the spectral probability density function, short-time spectral entropy, and short-time power, the short-time work entropy ratio is finally obtained; In step S3, the frame number signal is y i (n) = ω(n) * x((i - 1) * inc + n), where x(i) is the original vibration signal, n = 1, 2,... L, i = 1, 2,... fn, L is the frame length, inc is the frame shift length, fn is the total number of frames after framing, and ω(n) is the rectangular window function In step S3, Spectral probability density function Short-time spectral entropy Short-time power Short-time work entropy ratio PEF(i) = ln(1 + |PE i / H i |).

2. The performance evaluation method of the high-voltage circuit breaker according to claim 1, wherein: In step S1, the current and vibration signals during the opening and closing processes of the high-voltage circuit breaker are collected by a Hall sensor and an acceleration sensor respectively. The Hall sensor passes through the opening and closing coils, and the acceleration sensor is installed on the operating mechanism body of the circuit breaker.

3. The performance evaluation method of the high-voltage circuit breaker according to claim 1, characterized in that: In step S4, the calculation process of the threshold Det is as follows, Me = max{PEF(i)} Det = a×(Me - eth) + eth; where a is the threshold coefficient; compare the calculated short-time work entropy ratio with the threshold, and the moment exceeding the threshold is the occurrence moment of the operation mechanism action of the circuit breaker.

4. The performance evaluation method of the high-voltage circuit breaker according to claim 1, wherein: In step S5, the time difference is, Δt1 = t1 - t0 Δt2 = t2 - t0 Δt3 = t3 - t1.

5. The performance evaluation method of the high-voltage circuit breaker according to claim 4, wherein: In step S6, the specific calculation steps of the error are as follows, 6. The high-voltage circuit breaker performance evaluation method according to claim 5, characterized in that: In step S6, the fault judgment criterion of the high-voltage circuit breaker is, When Y1 ≥ 10%, it is determined that the coil is burned or jammed; When Y2 ≥ 10%, it is determined that the lubrication of the operating mechanism is poor; When it is determined that the closing spring is fatigued; When it is determined that the opening spring is fatigued.

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