A circuit breaker closing resistance damage detection system and method

Abstract

The present invention provides a system and method for detecting the damage state of a circuit breaker closing resistor, belonging to the technical field of circuit breaker closing resistor detection. The system comprises: a circuit breaker to be detected, lead wire bushings at both ends of the circuit breaker, a high-frequency signal generator, a high-frequency power amplifier, a high-frequency voltage and current acquisition device, a high-frequency current sensor, a power supply device, and a host computer. The circuit breaker includes a closing resistor string, a main break of the circuit breaker, and an auxiliary break of the circuit breaker. The first bushing, the auxiliary break of the circuit breaker, the main break of the circuit breaker, and the second bushing are connected in series in sequence, and the closing resistor string is connected in parallel at both ends of the auxiliary break of the circuit breaker. During detection, both breaks are in the open state. The high-frequency signal generator is controlled to output square wave signals and sine signals of different frequencies, and current is injected into the circuit through the high-frequency power amplifier. The circuit current and voltage are acquired, and the damage state of the closing resistor is determined based on the current and voltage waveforms.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit breaker closing resistance detection, and in particular to a circuit breaker closing resistance damage state detection system and method. Background Art

[0002] The closing resistor of a circuit breaker is an important component of the circuit breaker. It can suppress the closing inrush current and operating overvoltage during the closing process of the circuit breaker, and protect power equipment and lines. During the closing process of the circuit breaker, the closing resistor is subjected to mechanical and overcurrent shocks at the same time. The special and extreme stress makes the closing resistor very susceptible to damage during operation. However, the currently popular circuit breaker live detection methods cannot effectively detect the state of the closing resistor. Neither the ultrasonic method for detecting discharge nor the acoustic vibration method for detecting mechanical vibration can detect whether the closing resistor is damaged during operation after closing. This is because after the circuit breaker is put into operation, the two ends of the closing resistor are not subjected to voltage, and no current flows through them, so it is impossible to stimulate a detection signal that can reflect its status. Therefore, it is urgent to propose a technical means that can effectively detect the damage state of the closing resistor of the circuit breaker. Summary of the Invention

[0003] In view of this, the present invention provides a circuit breaker closing resistor damage status detection system and method, which uses the changes in high-frequency voltage and current signals caused by changes in high-frequency impedance characteristics to judge the circuit breaker closing resistor damage status in real time, providing a real-time and reliable detection solution.

[0004] The technical solution adopted by the embodiment of the present invention to solve the technical problem is:

[0005] A circuit breaker closing resistor damage detection system includes: a circuit breaker to be detected, lead wire bushings at both ends of the circuit breaker, a high-frequency signal generator, a high-frequency power amplifier, a high-frequency voltage and current acquisition device, a high-frequency current sensor, a power supply device, and a host computer; the lead wire bushings at both ends of the circuit breaker are used to connect to a busbar, and include a first bushing and a second bushing;

[0006] The circuit breaker includes a closing resistor string, a main break of the circuit breaker, and an auxiliary break of the circuit breaker;

[0007] The high-frequency signal generator is connected to the high-frequency power amplifier through a coaxial signal line; the high-frequency power amplifier and the circuit breaker are connected in parallel to form a loop;

[0008] The sensing end of the high-frequency current sensor is installed on the loop to collect the loop current signal;

[0009] A high-frequency voltage and current acquisition device is connected to the loop and the host computer to measure the loop voltage signal of the high-frequency power amplifier and the loop current signal of the high-frequency current sensor, and output them to the host computer;

[0010] The high-frequency power amplifier, high-frequency signal generator, and high-frequency voltage and current acquisition device are all connected to the power supply device;

[0011] During testing, the main and auxiliary breaker terminals of the circuit breaker are both in the open state. The high-frequency signal output by the high-frequency signal generator is amplified by the high-frequency power amplifier, and a high-frequency voltage signal is injected into the circuit. Voltage is applied to the circuit breaker through the first and second bushings. The high-frequency current sensor measures the loop current signal flowing through the loop, and the high-frequency voltage and current acquisition device measures the loop voltage signal of the loop. The host computer determines the damage status of the closing resistor based on the changes in the loop voltage and current caused by the changes in the high-frequency impedance characteristics of the loop.

[0012] The high frequency signal generator is connected to the host computer and is controlled by the host computer;

[0013] Host computer:

[0014] The high-frequency signal generator is controlled to sequentially output 10 groups of sinusoidal wave signals. The sinusoidal wave signals are amplified by a high-frequency power amplifier and then injected into the loop. The first loop voltage signal and the first loop current signal corresponding to each group of sinusoidal wave signals are recorded. The peak-to-peak value of the 10 groups of sinusoidal waves is 10V, and the peak-to-peak value increases sequentially in the range of 10kHz-100kHz with a step size of 10kHz.

[0015] The high-frequency signal generator is controlled to sequentially output 10 sets of square wave signals. The square wave signals are amplified by the high-frequency power amplifier and then injected into the loop. The second loop voltage signal and the second loop current signal corresponding to each set of square wave signals are recorded. The peak-to-peak value of the 10 sets of square wave signals is 10V, and the peak-to-peak value increases sequentially in the range of 10kHz-100kHz with a step size of 10kHz.

[0016] Draw waveforms of the first loop voltage signal, the first loop current signal, the second loop voltage signal, and the second loop current signal respectively. The waveforms are used to show how the signals change over time.

[0017] Determine the damage status of the closing resistor based on the waveforms:

[0018] Based on the waveforms obtained by injecting the sinusoidal wave signal, if there is a waveform with a voltage-to-current amplitude ratio greater than 500, it is determined that the closing resistor string in the circuit breaker is damaged;

[0019] Based on the waveforms obtained by injecting a square wave signal waveform, if the duration of the current in a single square wave cycle is less than 1 / 5 of the voltage waveform operating time, the circuit breaker's closing resistor string is determined to be damaged. The voltage waveform operating time refers to the duration of the waveform injection during a single square wave cycle when the signal is positive.

[0020] Preferably, the high-frequency signal generator generates a sinusoidal signal or a square wave signal with a repetition frequency of 10kHz-100kHz; the high-frequency power amplifier amplifies the signal power of the frequency band corresponding to the output waveform of the high-frequency signal generator.

[0021] Preferably, the high-frequency current sensor is a high-frequency Rogowski current measuring coil, which measures sinusoidal current signals and square wave current signals with a frequency range of not less than 100 kHz.

[0022] Preferably, the high-frequency voltage and current acquisition device has an analog bandwidth of not less than 1 MHz and acquires voltage signals within a repetition frequency range of 10 kHz to 100 kHz.

[0023] Preferably, the injection duration of a single set of square wave signals or sine wave signals into the loop is at least 5 cycles.

[0024] A method for detecting the damage state of a circuit breaker closing resistor is provided, using the aforementioned circuit breaker closing resistor damage state detection system, and the steps include:

[0025] Step S1, performing a tripping operation on two breakers in the circuit breaker;

[0026] Step S2: After the tripping action is completed, the high-frequency signal generator is controlled to sequentially output 10 sets of sinusoidal wave signals. The sinusoidal wave signals are amplified by the high-frequency power amplifier and then injected into the loop. The first loop voltage signal and the first loop current signal corresponding to each set of sinusoidal wave signals are recorded. The peak-to-peak value of the 10 sets of sinusoidal waves is 10V, and the peak-to-peak value increases in the range of 10kHz-100kHz in steps of 10kHz.

[0027] Step S3: Control the high-frequency signal generator to sequentially output 10 sets of square wave signals. The square wave signals are amplified by the high-frequency power amplifier and then injected into the loop. The second loop voltage signal and the second loop current signal corresponding to each set of square wave signals are recorded. The peak-to-peak value of the 10 sets of square wave signals is 10 V, and the peak-to-peak value increases sequentially in the range of 10 kHz to 100 kHz with a step size of 10 kHz.

[0028] Step S4, respectively drawing waveforms of the first loop voltage signal, the first loop current signal, the second loop voltage signal, and the second loop current signal, the waveforms being used to show how the signals change over time;

[0029] Step S5, determining the damage state of the closing resistor according to each waveform diagram, specifically includes:

[0030] Based on the waveforms obtained by injecting the sinusoidal wave signal, if there is a waveform with a voltage-to-current amplitude ratio greater than 500, it is determined that the closing resistor string in the circuit breaker is damaged;

[0031] Based on the waveforms obtained by injecting the square wave signal waveform, if the duration of the current in a single square wave cycle is less than 1 / 5 of the working time of the voltage waveform, it is determined that the closing resistor string of the circuit breaker is damaged.

[0032] As can be seen from the above technical solution, the embodiments of the present invention provide a system and method for detecting the damage state of a circuit breaker closing resistor. The system comprises a circuit breaker to be detected, lead wire bushings at both ends of the circuit breaker, a high-frequency signal generator 7, a high-frequency power amplifier 6, a high-frequency voltage and current acquisition device 8, a high-frequency current sensor 9, a power supply device 10, and a host computer. The circuit breaker includes a closing resistor string 1, a circuit breaker main break 5, and a circuit breaker auxiliary break 4. The first bushing 2, the circuit breaker auxiliary break 4, the circuit breaker main break 5, and the second bushing 3 are connected in series in sequence, and the closing resistor string 1 is connected in parallel at both ends of the circuit breaker auxiliary break 4. First, the two breaks in the circuit breaker are disconnected, the high-frequency signal generator 7 is controlled to output square wave signals and sine signals of different frequencies, and current is injected into the circuit through the high-frequency power amplifier 6. The circuit current and voltage are collected, and then the damage state of the closing resistor is determined based on the current and voltage waveforms. The present invention uses the changes in high-frequency voltage and current signals caused by changes in high-frequency impedance characteristics to determine the damage state of the circuit breaker closing resistor in real time, providing a real-time and reliable detection solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are intended only to illustrate preferred embodiments and are not to be construed as limiting the present invention. It should be understood that the drawings described below are merely examples of the present invention, and that those skilled in the art will be able to derive other drawings from these drawings without inventive effort. Throughout the drawings, identical reference numerals are used to denote identical components.

[0034] Figure 1 The figure is a schematic diagram of a circuit breaker closing resistor damage status detection system according to the present invention.

[0035] Figure 2a It is a parallel structure circuit breaker (Xikai circuit breaker, Pinggao circuit breaker).

[0036] Figure 2b It is a series structure circuit breaker (New Northeast circuit breaker, ABB circuit breaker).

[0037] Figure 3 Normal state high frequency sinusoidal signal voltage and current waveform.

[0038] Figure 4 The voltage and current waveforms of high-frequency sinusoidal signals in the damaged state.

[0039] Figure 5 This is the voltage and current waveform of the high-frequency square wave signal in normal state.

[0040] Figure 6 The voltage and current waveforms of high-frequency sinusoidal signals in the damaged state. DETAILED DESCRIPTION

[0041] Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0042] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of the present invention shall be as defined in the attached claims.

[0043] To facilitate understanding of the embodiments of the present invention, further explanation will be given below using specific embodiments as examples in conjunction with the accompanying drawings, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0044] The present invention utilizes the fact that the high-frequency impedance characteristics change when the closing resistor is damaged. By applying a high-frequency signal, the changes in the high-frequency voltage and current signals caused by the change in the high-frequency impedance characteristics are used to judge the damage state of the closing resistor, thereby being able to effectively and quickly detect the damage state of the closing resistor.

[0045] refer to Figure 1 As shown, the system of the present invention comprises a circuit breaker to be tested, lead wire bushings at both ends of the circuit breaker, a high-frequency signal generator 7, a high-frequency power amplifier 6, a high-frequency voltage and current acquisition device 8, a high-frequency current sensor 9, a power supply device 10, and a host computer; the lead wire bushings at both ends of the circuit breaker are used to connect to the busbar, and include a first bushing 2 and a second bushing 3;

[0046] refer to Figure 2a and Figure 2b As shown, the circuit breaker includes a closing resistor string 1, a main break 5, and an auxiliary break 4. When the circuit breaker is in the open state, the break is equivalent to a small capacitor.

[0047] The high-frequency signal generator 7 is connected to the high-frequency power amplifier 6 via a coaxial signal line; the high-frequency power amplifier 6 is connected in parallel with the circuit breaker. Specifically, the lead-out end of the first bushing 2 and the lead-out end of the second bushing 3 are connected to the two connection terminals of the high-frequency power amplifier 6, so that the high-frequency power amplifier 6 and the circuit breaker form a loop together.

[0048] The induction end of the high-frequency current sensor 9 is installed on the loop, and the output end is connected to the high-frequency voltage and current acquisition device 8, for collecting the loop current signal and outputting it to the high-frequency voltage and current acquisition device 8;

[0049] A high-frequency voltage and current acquisition device 8 is connected to the loop and is used to measure the loop voltage signal of the high-frequency power amplifier 6 and the loop current signal of the high-frequency current sensor 9; the high-frequency voltage and current acquisition device 8 is connected to the host computer and is used to output the collected loop voltage signal and loop current signal to the host computer;

[0050] The high-frequency power amplifier 6, the high-frequency signal generator 7, and the high-frequency voltage and current acquisition device 8 are all connected to the power supply device 10 and are powered by the power supply device 10;

[0051] The high-frequency signal generator 7 is used to generate a sine wave signal or a square wave signal with a repetition frequency of 10kHz-100kHz; the high-frequency power amplifier 6 is used to amplify the signal power of the frequency band corresponding to the output waveform of the high-frequency signal generator 7.

[0052] During detection, the main break 5 and the auxiliary break 4 of the circuit breaker are both in the open state. The high-frequency signal output by the high-frequency signal generator 7 is amplified by the high-frequency power amplifier 6, and a high-frequency voltage signal is injected into the circuit, and voltage is applied to the circuit breaker through the first bushing 2 and the second bushing 3 of the circuit breaker; the high-frequency current sensor 9 measures the loop current signal flowing through the loop, and the high-frequency voltage and current acquisition device 8 measures the loop voltage signal of the loop. The host computer determines the damage status of the closing resistor based on the changes in the loop voltage and current caused by the changes in the high-frequency impedance characteristics of the loop.

[0053] The high-frequency current detection sensor 9 adopts a high-frequency Rogowski current measuring coil, which is used to measure sinusoidal current signals and square wave current signals with a frequency range of not less than 100kHz;

[0054] The high-frequency voltage and current acquisition device 8 has an analog bandwidth of not less than 1 MHz and is used to acquire voltage signals within a repetition frequency range of 10 kHz to 100 kHz.

[0055] The high-frequency signal generator 7 is connected to the host computer and is controlled by the host computer; the host computer is used to:

[0056] The host computer is used for:

[0057] The high-frequency signal generator 7 is controlled to sequentially output 10 groups of sinusoidal wave signals. The sinusoidal wave signals are amplified by the high-frequency power amplifier 6 and then injected into the loop. The first loop voltage signal and the first loop current signal corresponding to each group of sinusoidal wave signals are recorded. The peak-to-peak value of the 10 groups of sinusoidal waves is 10 V, and the peak-to-peak value increases sequentially in a range of 10 kHz to 100 kHz with a step size of 10 kHz. The injection duration of a single group of sinusoidal wave signals into the loop is at least 5 cycles.

[0058] The high-frequency signal generator 7 is controlled to output 10 groups of square wave signals in sequence. The square wave signals are amplified by the high-frequency power amplifier 6 and then injected into the loop. The second loop voltage signal and the second loop current signal corresponding to each group of square wave signals are recorded. The peak-to-peak value of the 10 groups of square wave signals is 10V, and the peak-to-peak value increases in the range of 10kHz-100kHz with an interval of 10kHz. The injection duration of a single group of square wave signals or sine wave signals into the loop is at least 5 cycles.

[0059] Draw waveforms of the first loop voltage signal, the first loop current signal, the second loop voltage signal, and the second loop current signal respectively. The waveforms are used to show how the signals change over time.

[0060] Determine the damage status of the closing resistor based on the waveforms:

[0061] The first circuit voltage signal and the first circuit current signal are collected based on the injection of a sine wave signal in the range of 10kHz-100kHz. Based on the waveforms corresponding to each frequency, if there is a waveform with a voltage to current amplitude ratio greater than 500, it is determined that the closing resistor string 1 in the circuit breaker is damaged;

[0062] The second-loop voltage signal and the second-loop current signal are collected based on the injection of a square wave signal waveform in the range of 10kHz-100kHz. According to the waveform diagrams corresponding to each frequency, if the duration of the current in a single square wave cycle is less than 1 / 5 of the voltage waveform operating time, it is determined that the closing resistor string 1 of the circuit breaker is damaged. The voltage waveform operating time refers to the waveform injection duration of the positive signal in a single square wave cycle of the signal.

[0063] In the system, the high-frequency signal generator applies a high-frequency signal to the closing resistance of the circuit breaker to be detected through a high-frequency power amplifier, the high-frequency current sensor measures the output current signal of the high-frequency power amplifier, and the high-frequency voltage and current acquisition device collects the output voltage of the high-frequency power amplifier and the output signal measured by the high-frequency current sensor. The detection method determines the damage state of the closing resistance by analyzing the measured voltage and current signals. By utilizing the special law that the change of the high-frequency impedance characteristics when the closing resistance is damaged, and then affecting the change of the current signal under the action of high-frequency voltage, the damage state of the closing resistance of the circuit breaker is detected. Based on Figure 1The present invention provides a method for detecting the damage state of a circuit breaker closing resistor, comprising the following steps:

[0064] Step S1, performing a tripping operation on two breakers in the circuit breaker;

[0065] Step S2, after the opening action is completed, the high-frequency signal generator (7) is controlled to output 10 groups of sinusoidal wave signals in sequence, the sinusoidal wave signals are amplified by the high-frequency power amplifier (6) and then injected into the loop, and the first loop voltage signal and the first loop current signal corresponding to each group of sinusoidal wave signals are recorded; the peak-to-peak value of the 10 groups of sinusoidal waves is 10V, and increases in step size of 10kHz in the range of 10kHz-100kHz; the injection time of a single group of sinusoidal wave signals into the loop is at least 5 cycles.

[0066] Step S3: Control the high-frequency signal generator 7 to sequentially output 10 groups of square wave signals. The square wave signals are amplified by the high-frequency power amplifier 6 and then injected into the loop. The second loop voltage signal and the second loop current signal corresponding to each group of square wave signals are recorded. The peak-to-peak value of the 10 groups of square wave signals is 10 V, and the peak-to-peak value increases in the range of 10 kHz to 100 kHz with a step size of 10 kHz. The injection duration of a single group of square wave signals into the loop is at least 5 cycles.

[0067] Step S4, respectively drawing waveforms of the first loop voltage signal, the first loop current signal, the second loop voltage signal, and the second loop current signal, the waveforms being used to show how the signals change over time;

[0068] Step S5, determining the damage state of the closing resistor according to each waveform diagram, specifically includes:

[0069] The first circuit voltage signal and the first circuit current signal are collected based on the injection of a sine wave signal in the range of 10kHz-100kHz. Based on the waveforms corresponding to each frequency, if there is a waveform with a voltage to current amplitude ratio greater than 500, it is determined that the closing resistor string 1 in the circuit breaker is damaged;

[0070] The second-loop voltage signal and the second-loop current signal are collected based on the injection of a square wave signal waveform in the range of 10kHz-100kHz. According to the waveform diagrams corresponding to each frequency, if the duration of the current in a single square wave cycle is less than 1 / 5 of the voltage waveform operating time, it is determined that the closing resistor string 1 of the circuit breaker is damaged. The voltage waveform operating time refers to the waveform injection duration of the positive signal in a single square wave cycle of the signal.

[0071] The present invention provides a preferred embodiment of a method for detecting a damage state of a closing resistor of a circuit breaker, wherein the severity of the damage state of the closing resistor is determined by comparing different historical measurement data.

[0072] In one embodiment, Figure 3 For normal status, Figure 4 In the damaged state, Figure 4 and Figure 3 In comparison, under the action of high-frequency sinusoidal signal (10kHz), the resistance impedance increases significantly and the loop current decreases. Specifically, Figure 3 The magnitude of the medium voltage and current is 13.33, which is less than 500. This indicates that the closing resistor is not damaged. Figure 4 The amplitude of the medium voltage and current is 1333, which is much larger than 500. It can be judged that the closing resistor is damaged. Figure 4 The comparison between the amplitude of the medium voltage and the current is , which can be used to determine that the closing resistor is damaged;

[0073] In one embodiment, Figure 5 For normal status, Figure 6 In the damaged state, Figure 6 and Figure 5 In contrast, under the action of a square wave, for a normal resistor, since it has both capacitance and resistance, current flows at the rising and falling edges of high frequencies and in the flat region of low frequencies. However, for a damaged resistor, since the large inductance completely blocks the current, only a pulse signal is generated at the rising and falling edges due to the capacitance effect. There are obvious differences in the signal waveforms of the two. Specifically, Figure 5 The duration of the medium current waveform is 0.025ms, the operating time of the voltage is 0.025ms, and the duration of the current is greater than 1 / 5 of the voltage operating time (0.005ms). It can be judged that the closing resistance is normal; Figure 5 The duration of the medium current waveform is only 0.0001ms, and the working time of the voltage is 0.025ms. The duration of the current is much less than 1 / 5 of the voltage working time (0.005ms), which can be used to determine that the closing resistor is damaged.

[0074] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments and application fields. The above-mentioned specific embodiments are merely illustrative and instructive, and are not restrictive. A person skilled in the art, guided by this specification and without departing from the scope of protection of the claims of the present invention, may also devise various forms, all of which fall within the scope of protection of the present invention.

Claims

1. A circuit breaker closing resistor damage status detection system, characterized in that: include: A circuit breaker to be tested, lead wire bushings at both ends of the circuit breaker, a high-frequency signal generator, a high-frequency power amplifier, a high-frequency voltage and current acquisition device, a high-frequency current sensor, a power supply device, and a host computer; the lead wire bushings at both ends of the circuit breaker are used to connect to the busbar, including a first bushing and a second bushing; The circuit breaker includes a closing resistor string, a main break of the circuit breaker, and an auxiliary break of the circuit breaker; The high-frequency signal generator is connected to the high-frequency power amplifier through a coaxial signal line; the high-frequency power amplifier and the circuit breaker are connected in parallel to form a loop; The sensing end of the high-frequency current sensor is installed on the loop to collect the loop current signal; A high-frequency voltage and current acquisition device is connected to the loop and the host computer to measure the loop voltage signal of the high-frequency power amplifier and the loop current signal of the high-frequency current sensor, and output them to the host computer; The high-frequency power amplifier, high-frequency signal generator, and high-frequency voltage and current acquisition device are all connected to the power supply device; During testing, the main and auxiliary breaker terminals of the circuit breaker are both in the open state. The high-frequency signal output by the high-frequency signal generator is amplified by the high-frequency power amplifier, and a high-frequency voltage signal is injected into the circuit. Voltage is applied to the circuit breaker through the first and second bushings. The high-frequency current sensor measures the loop current signal flowing through the loop, and the high-frequency voltage and current acquisition device measures the loop voltage signal of the loop. The host computer determines the damage status of the closing resistor based on the changes in the loop voltage and current caused by the changes in the high-frequency impedance characteristics of the loop. The high frequency signal generator is connected to the host computer and is controlled by the host computer; Host computer: The high-frequency signal generator is controlled to sequentially output 10 groups of sinusoidal wave signals. The sinusoidal wave signals are amplified by a high-frequency power amplifier and then injected into the loop. The first loop voltage signal and the first loop current signal corresponding to each group of sinusoidal wave signals are recorded. The peak-to-peak value of the 10 groups of sinusoidal waves is 10V, and the peak-to-peak value increases sequentially in the range of 10kHz-100kHz with a step size of 10kHz. The high-frequency signal generator is controlled to sequentially output 10 sets of square wave signals. The square wave signals are amplified by the high-frequency power amplifier and then injected into the loop. The second loop voltage signal and the second loop current signal corresponding to each set of square wave signals are recorded. The peak-to-peak value of the 10 sets of square wave signals is 10V, and the peak-to-peak value increases sequentially in the range of 10kHz-100kHz with a step size of 10kHz. Draw waveforms of the first loop voltage signal, the first loop current signal, the second loop voltage signal, and the second loop current signal respectively. The waveforms are used to show how the signals change over time. Determine the damage status of the closing resistor based on the waveforms: Based on the waveforms obtained by injecting the sinusoidal wave signal, if there is a waveform with a voltage-to-current amplitude ratio greater than 500, it is determined that the closing resistor string in the circuit breaker is damaged; Based on the waveforms obtained by injecting a square wave signal waveform, if the duration of the current in a single square wave cycle is less than 1 / 5 of the voltage waveform operating time, the circuit breaker's closing resistor string is determined to be damaged. The voltage waveform operating time refers to the duration of the waveform injection during a single square wave cycle when the signal is positive.

2. The circuit breaker closing resistor damage status detection system according to claim 1, characterized in that: The high-frequency signal generator generates a sine wave signal or a square wave signal with a repetition frequency of 10kHz-100kHz; the high-frequency power amplifier amplifies the signal power of the frequency band corresponding to the output waveform of the high-frequency signal generator.

3. The circuit breaker closing resistor damage status detection system according to claim 2, characterized in that: The high-frequency current sensor is a high-frequency Rogowski current measuring coil that measures sinusoidal current signals and square wave current signals with a frequency range of not less than 100kHz.

4. The circuit breaker closing resistor damage status detection system according to claim 3, characterized in that: High-frequency voltage and current acquisition device, with an analog bandwidth of not less than 1MHz, collects voltage signals within the repetition frequency range of 10kHz-100kHz.

5. The circuit breaker closing resistor damage status detection system according to claim 4, characterized in that: The injection duration of a single set of square wave signals or sine wave signals into the loop is at least 5 cycles.

6. A method for detecting damage status of closing resistance of a circuit breaker, characterized in that: The circuit breaker closing resistor damage state detection system according to any one of claims 1 to 5 comprises the following steps: Step S1, performing a tripping operation on two breakers in the circuit breaker; Step S2: After the tripping action is completed, the high-frequency signal generator is controlled to sequentially output 10 sets of sinusoidal wave signals. The sinusoidal wave signals are amplified by the high-frequency power amplifier and then injected into the loop. The first loop voltage signal and the first loop current signal corresponding to each set of sinusoidal wave signals are recorded. The peak-to-peak value of the 10 sets of sinusoidal waves is 10V, and the peak-to-peak value increases in the range of 10kHz-100kHz in steps of 10kHz. Step S3: Control the high-frequency signal generator to sequentially output 10 sets of square wave signals. The square wave signals are amplified by the high-frequency power amplifier and then injected into the loop. The second loop voltage signal and the second loop current signal corresponding to each set of square wave signals are recorded. The peak-to-peak value of the 10 sets of square wave signals is 10 V, and the peak-to-peak value increases sequentially in the range of 10 kHz to 100 kHz with a step size of 10 kHz. Step S4, respectively drawing waveforms of the first loop voltage signal, the first loop current signal, the second loop voltage signal, and the second loop current signal, the waveforms being used to show how the signals change over time; Step S5, determining the damage state of the closing resistor according to each waveform diagram, specifically includes: Based on the waveforms obtained by injecting the sinusoidal wave signal, if there is a waveform with a voltage-to-current amplitude ratio greater than 500, it is determined that the closing resistor string in the circuit breaker is damaged; Based on the waveforms obtained by injecting the square wave signal waveform, if the duration of the current in a single square wave cycle is less than 1 / 5 of the working time of the voltage waveform, it is determined that the closing resistor string of the circuit breaker is damaged.

Images