A cable fault flash detector performance evaluation device and method

Abstract

The present invention belongs to the field of performance evaluation of a full range of instruments for power cable fault detection, and specifically relates to a performance evaluation device and method for a cable fault flash detector, wherein the evaluation device includes a CPLD control circuit, a dual-channel pulse driver, a dual-channel selection pulse generating circuit, a pulse width detection circuit, and a pulse transformer. The present invention can achieve the detection of the flash detector's transmitted pulse waveform and the control of the output simulated reflected pulse waveform, and can automatically detect the transmitted pulse waveform width and start time according to the pulse width detection circuit, and realize the output pulse waveform positive and negative phase switching and amplitude adjustment through the CPLD control circuit. At the same time, the pulse transformer avoids the oscillation and distortion of the pulse waveform caused by terminal load mismatch, thereby effectively simulating the actual working conditions of the flash detector. The pulse waveform generated by the present invention has steep rising and falling edges and obvious inflection points, and is suitable for the detection of the measurement accuracy of cable fault flash detectors with high accuracy requirements.

Description

Technical Field

[0001] The invention belongs to the field of performance evaluation of a full range of power cable fault detection instruments, and in particular relates to a performance evaluation device and method for a cable fault flash detector. Background Art

[0002] At present, the principles adopted by power cable fault diagnosis and ranging detection technology are mainly divided into impedance method and traveling wave method. Both have excellent performance in fault diagnosis and high measurement accuracy. Traveling wave fault location has been widely used in cable fault location and cable length measurement. Among them, single-ended A-type traveling wave fault location and double-ended D-type traveling wave fault location are more representative. With the development of technology, cable fault flash detectors based on single-ended ranging method are widely used due to their small investment, low cost, and no need for synchronous work compared to double-ended ranging method.

[0003] Figure 1 The electrical model of the cable is equivalent to a series-parallel connection of several components such as resistance, capacitance, inductance and conductance. These components are called the distributed parameters of the cable, that is, the cable is divided into several units. The principle of fault location by the traveling wave method is that when the cable is in normal condition, the impedance of the equivalent power of each unit is equal. At this time, the traveling wave can pass smoothly to the terminal during the cable transmission process. When a cable fails at a certain section, the impedance of the equivalent circuit of the section changes. Due to impedance mismatch, the traveling wave is reflected at this place, thereby locating the fault location.

[0004] Due to the large number of cable fault flash detector manufacturers, complex technical routes, and uneven performance, it is often impossible to accurately determine the type and location of cable faults during actual fault detection, which seriously affects the judgment of key cable performance indicators, the efficiency of cable fault detection, and the quality of cable status evaluation. Due to the lack of a practical method for simulating cable fault conditions, the current inspection methods and performance evaluation technologies for cable fault flash detectors mainly use physical cables. This inspection method is expensive, subject to many interference factors, and is only suitable for short-distance measurement, and cannot meet the working conditions for accuracy inspection of cable fault flash detectors. Therefore, there is an urgent need to study relevant inspection technologies and devices to guide the inspection and performance evaluation of cable fault flash detectors.

[0005] The Chinese patent with the announcement number CN101706564B discloses a standard device for a cable fault flash detector, whose core circuit includes a control module, a cable core multiplexing module, an input signal conditioning module, a signal delay feedback module, and a high-speed amplifier and drive module. The relationship between the modules is: the cable fault flash detector to be tested is connected to the cable core multiplexing module, the cable core multiplexing module, the input signal conditioning module, the control module, the signal delay feedback module, and the high-speed amplifier and drive module are connected in sequence, and the high-speed amplifier and drive module is connected to the input signal conditioning module. This standard device for a cable fault flash detector simulates the time domain reflection characteristics of a physical cable by sending a reflection pulse through a signal delay feedback module, a high-speed amplifier and a drive module. However, since the scheme has no load terminal matching design, when facing cable fault flash detectors of different brands on the market, its pulse waveform will cause waveform vibration, distortion and other phenomena due to impedance mismatch, which is not conducive to the calibration of the distance measurement function of the cable fault flash detector; at the same time, since the design can only output a unipolar pulse square wave, it cannot meet the detection requirements of the fault type identification function of the cable fault flash detector. Summary of the invention

[0006] Aiming at the shortcomings of the accuracy inspection method of the traditional cable fault flash detector, the present invention provides a performance evaluation device and method for a cable fault flash detector. The device and method analyze the law of traveling wave propagation in the cable, establish the correlation characteristic model of different cable fault types, design a circuit model for generating pulse square waves based on CPLD combined with high-speed conduction MOSFET as a switch, study the problem of adjusting the local characteristics of the traveling wave pulse width, adjust the pulse edge, amplitude overshoot oscillation and impedance matching, and finally obtain a traveling wave with a relatively ideal pulse waveform.

[0007] The present invention is implemented by the following technical solutions:

[0008] A performance evaluation device for a cable fault flash detector, comprising a CPLD control circuit, a dual-channel pulse driver, a dual-channel strobe pulse generating circuit, a pulse width detection circuit, and a pulse transformer;

[0009] The signal input end of the pulse transformer is connected to the signal output end of the cable fault flash detector, and is used to receive the incident pulse output by the cable fault flash detector, and output the incident pulse to the pulse width detection circuit;

[0010] The pulse width detection circuit is connected to the pulse transformer and the CPLD control circuit, and is used to receive the incident pulse sent by the pulse transformer, detect the pulse signal and generate a trigger level, and send it to the CPLD control circuit;

[0011] The CPLD control circuit is connected to the pulse width detection circuit, and is used to obtain a pulse trigger signal and a pulse width signal of the incident pulse according to the trigger level detected by the pulse width detection circuit, and output a pulse control signal whose pulse width is the same as the incident pulse and whose delay time is counted from the edge of the pulse trigger signal. The CPLD control circuit is also used to select and control one of the dual-channel pulse drivers to output the pulse control signal according to different fault types set by software;

[0012] The dual-path strobe pulse generating circuit is used to make the corresponding positive polarity pulse generating circuit or negative polarity pulse generating circuit work under the control of the pulse control signal output by the dual-path pulse driver to generate a reflection pulse signal of the corresponding polarity;

[0013] The pulse transformer is used to perform impedance matching and polarity change on the reflected pulse signal generated by the dual-path selection pulse generating circuit, convert it into a reflected pulse square wave signal and send it to the cable fault flash detector. The cable fault flash detector detects the reflected pulse square wave signal and calculates the fault distance, compares it with the fault distance set by the performance evaluation device of the cable fault flash detector, and calculates the error, thereby realizing the performance evaluation of the flash detector.

[0014] Furthermore, it also includes a DC power supply connected to the CPLD control circuit and the dual-path strobe pulse generating circuit. The CPLD control circuit is also used to adjust the voltage amplitude of the DC power supply and output it to the power supply end of the positive polarity pulse generating circuit or the negative polarity pulse generating circuit in the dual-path strobe pulse generating circuit to adjust the waveform amplitude of the output reflected pulse.

[0015] Furthermore, the dual-path selection pulse generating circuit includes a positive polarity pulse generating circuit and a negative polarity pulse generating circuit, the positive polarity pulse generating circuit includes a positive phase pulse current limiting resistor, a positive phase pulse output switch tube, a positive phase pulse energy storage capacitor, and a positive phase pulse discharge resistor, and the negative polarity pulse generating circuit includes a reverse phase pulse current limiting resistor, a reverse phase pulse output switch tube, a reverse phase pulse energy storage capacitor, and a reverse phase pulse discharge resistor; the control signal output end of the dual-path pulse driver is connected to the control end of the positive phase pulse output switch tube and the reverse phase pulse output switch tube.

[0016] Furthermore, the voltage U output by the DC power supply is 0 The positive phase pulse current limiting resistor is connected in series with the positive phase pulse output switch tube and then grounded. The node of the positive phase pulse current limiting resistor and the positive phase pulse output switch tube is connected in series with the positive phase pulse energy storage capacitor and the positive phase pulse discharge resistor and then grounded. The two ends of the positive phase pulse discharge resistor are connected to one input end of the pulse transformer as the output end of the negative polarity pulse generating circuit; the voltage U output by the DC power supply 0The inverting pulse current limiting resistor is connected in series with the inverting pulse output switch tube and then grounded. The node of the inverting pulse current limiting resistor and the inverting pulse output switch tube is connected in series with the inverting pulse energy storage capacitor and the inverting pulse discharge resistor and then grounded. The two ends of the inverting pulse discharge resistor are connected to the other input end of the pulse transformer as the output end of the positive polarity pulse generating circuit.

[0017] Furthermore, the positive-phase pulse output switch tube and the negative-phase pulse output switch tube are both MOSFET field-effect tubes, one end of the positive-phase pulse current-limiting resistor is connected to a DC power supply, and the other end is connected to the drain of the MOSFET field-effect tube, the source of the MOSFET field-effect tube is grounded, and the gate of the MOSFET field-effect tube is connected to the control signal output end of the dual-path pulse driver, one end of the negative-phase pulse current-limiting resistor is connected to a DC power supply, and the other end is connected to the drain of the MOSFET field-effect tube, the source of the MOSFET field-effect tube is grounded, and the gate of the MOSFET field-effect tube is connected to the control signal output end of the dual-path pulse driver.

[0018] Furthermore, the pulse transformer includes a transformer, a DC blocking capacitor and a terminal load resistor; the primary side of the transformer is connected to the signal output end of the dual-path strobing pulse generating circuit, the secondary side of the transformer is connected in parallel with the terminal load resistor, the node of the terminal load resistor and the same-name end of the secondary side of the transformer is connected to one end of the DC blocking capacitor, and the other end of the DC blocking capacitor serves as the signal output end of the pulse transformer.

[0019] Furthermore, the pulse width detection circuit is a high-speed voltage comparator.

[0020] A cable fault flash detector performance evaluation method is implemented using the above evaluation device, and the method comprises the following steps:

[0021] The pulse transformer receives the incident pulse output by the cable fault flash detector and sends it to the pulse width detection circuit;

[0022] The pulse width detection circuit detects the pulse signal and generates a trigger level, and sends it to the CPLD control circuit;

[0023] The CPLD control circuit obtains a pulse trigger signal and a pulse width signal of the incident pulse according to the trigger level detected by the pulse width detection circuit, outputs a pulse control signal with a pulse width the same as the incident pulse and a delay time starting from the edge of the pulse trigger signal, and selects one of the dual-channel pulse drivers to output the pulse control signal according to different fault types set by the software;

[0024] The dual-path strobe pulse generating circuit enables the corresponding positive polarity pulse generating circuit or negative polarity pulse generating circuit to work under the control of the pulse control signal output by the dual-path pulse driver, thereby generating a reflection pulse signal of corresponding polarity;

[0025] The pulse transformer performs impedance matching and polarity change on the reflected pulse signal generated by the dual-path gate pulse generating circuit, converts it into a reflected pulse square wave signal and sends it to the cable fault flash detector;

[0026] The cable fault flash detector detects the reflected pulse square wave signal and calculates the fault distance, compares it with the fault distance set by the cable fault flash detector performance evaluation device, and calculates the error, thereby realizing the performance evaluation of the flash detector.

[0027] Furthermore, the CPLD control circuit adjusts the voltage amplitude of the DC power supply and outputs it to the power supply end of the positive polarity pulse generating circuit or the negative polarity pulse generating circuit in the dual-path gate pulse generating circuit to adjust the waveform amplitude of the output reflected pulse.

[0028] Furthermore, the pulse width of the reflected pulse waveform sent by the pulse transformer to the cable fault flash detector is consistent with the width of the pulse waveform sent by the cable fault flash detector.

[0029] The present invention controls the pulse width detection circuit, CPLD control circuit, DC power supply, pulse generating circuit and pulse transformer to achieve detection of the pulse waveform emitted by the flash tester and control of the output simulated reflected pulse waveform; and can automatically detect the emission pulse waveform width and start time according to the pulse width detection circuit, realize the positive and negative phase switching and amplitude adjustment of the output pulse waveform through the CPLD control circuit, and at the same time, the pulse transformer avoids the oscillation and distortion of the pulse waveform caused by the mismatch of the terminal load, thereby effectively simulating the actual working conditions of the flash tester. The traveling wave pulse signal formed by the circuit of the present invention has the characteristics of pulse width adaptive matching, adjustable pulse amplitude, steep edge, etc., which is suitable as a standard fault reflection wave of the single-ended fault location method, and can realize the measurement accuracy test of the cable fault flash tester in the fault distance measurement function, speed measurement function and fault type identification function. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is the schematic diagram of the cable equivalent circuit model;

[0031] Figure 2 A schematic diagram of the use of the performance evaluation device for the cable fault flash detector of the present invention;

[0032] Figure 3 This is a circuit principle block diagram of a performance evaluation device for a cable fault flash detector according to the present invention;

[0033] Figure 4 The circuit structure diagram of the dual-path gate pulse generating circuit and the pulse transformer in the present invention;

[0034] Figure 5It is the actual test waveform of the cable fault flash detector performance evaluation device of the present invention.

[0035] In the figure: 1—CPLD control circuit, 2—dual-channel pulse driver, 3—dual-channel selection pulse generating circuit, 4—pulse width detection circuit, 5—DC power supply, 6—pulse transformer, 7—cable fault flash detector, 8—reverse pulse current limiting resistor, 9—reverse pulse output switch tube, 10—reverse pulse energy storage capacitor, 11—reverse pulse discharge resistor, 12—positive pulse current limiting resistor, 13—positive pulse output switch tube, 14—positive pulse energy storage capacitor, 15—positive pulse discharge resistor, 16—DC blocking capacitor, 17—terminal load resistor, 18—transformer. DETAILED DESCRIPTION

[0036] The following further describes the embodiments of the present invention in conjunction with the accompanying drawings, and the specific embodiments do not limit the present invention in any way.

[0037] See also Figure 2 and Figure 3 One embodiment of a cable fault flash detector performance evaluation device of the present invention includes a CPLD control circuit 1, a dual-channel pulse driver 2, a dual-channel selection pulse generating circuit 3, a pulse width detection circuit 4, a DC power supply 5, and a pulse transformer 6.

[0038] The signal input end of the pulse transformer 6 is connected to the signal output end of the cable fault flash detector 7, for receiving the incident pulse output by the cable fault flash detector 7, and outputting the incident pulse to the pulse width detection circuit 4;

[0039] The pulse width detection circuit 4 is connected to the pulse transformer 6 and the CPLD control circuit 1. The pulse width detection circuit 4 is a high-speed voltage comparator, which is used to receive the incident pulse sent by the pulse transformer 6, detect the pulse signal and generate a trigger level, and send it to the CPLD control circuit 1;

[0040] The CPLD control circuit 1 is connected to the pulse width detection circuit 4, and is used to obtain a pulse trigger signal and a pulse width signal of the incident pulse according to the trigger level detected by the pulse width detection circuit 4, and output a pulse control signal whose pulse width is the same as the incident pulse and whose delay time starts from the edge of the pulse trigger signal;

[0041] The CPLD control circuit 1 is also used to select and control one of the two-way pulse drivers 2 to output the pulse control signal according to different fault types set by software;

[0042] The dual-path strobe pulse generating circuit 3 is used to make the corresponding positive polarity pulse generating circuit or negative polarity pulse generating circuit work under the control of the pulse control signal output by the dual-path pulse driver 2, and generate a reflection pulse signal of the corresponding polarity;

[0043] The pulse transformer 6 is used to perform impedance matching and polarity change on the reflected pulse signal generated by the dual-path selection pulse generating circuit 3, convert it into a reflected pulse square wave signal and send it to the cable fault flash detector 7. The flash detector 7 detects the reflected pulse square wave signal and calculates the fault distance, compares it with the fault distance set by the cable fault flash detector performance evaluation device of the present invention, and calculates the error, thereby realizing the performance evaluation of the flash detector.

[0044] The DC power supply 5 is connected to the CPLD control circuit 1 and the dual-path strobe pulse generating circuit 3. The CPLD control circuit 1 is used to adjust the voltage amplitude of the DC power supply 5 and output it to the power supply end of the positive polarity pulse generating circuit or the negative polarity pulse generating circuit in the dual-path strobe pulse generating circuit 3 to adjust the waveform amplitude of the output reflected pulse.

[0045] See also Figure 4 As shown, the dual-path gating pulse generating circuit 3 includes a positive polarity pulse generating circuit and a negative polarity pulse generating circuit, the positive polarity pulse generating circuit includes a positive phase pulse current limiting resistor 12, a positive phase pulse output switch tube 13, a positive phase pulse energy storage capacitor 14, and a positive phase pulse discharge resistor 15, and the negative polarity pulse generating circuit includes a reverse phase pulse current limiting resistor 8, a reverse phase pulse output switch tube 9, a reverse phase pulse energy storage capacitor 10, and a reverse phase pulse discharge resistor 11. In one embodiment, the positive phase pulse output switch tube 13 and the reverse phase pulse output switch tube 9 are both MOSFET field effect tubes, and the control signal output end of the dual-path pulse driver 2 is connected to the control end of the positive phase pulse output switch tube 13 and the reverse phase pulse output switch tube 9, such as the gate of the MOSFET field effect tube.

[0046] The voltage U output by the DC power supply 5 0 The positive phase pulse current limiting resistor 12 is connected in series with the positive phase pulse output switch tube 13 and then grounded (one end of the positive phase pulse current limiting resistor 12 is connected to the DC power supply 5, and the other end is connected to the drain of the MOSFET field effect tube, the source of the MOSFET field effect tube is grounded, and the gate of the MOSFET field effect tube is connected to the control signal output end of the dual-path pulse driver 2), the node of the positive phase pulse current limiting resistor 12 and the positive phase pulse output switch tube 13 is connected in series through the positive phase pulse energy storage capacitor 14 and the positive phase pulse discharge resistor 15 and then grounded, and the two ends of the positive phase pulse discharge resistor 15 are connected to an input end of the pulse transformer 6 as the output end of the negative polarity pulse generating circuit.

[0047] The voltage U output by the DC power supply 5 0The inverting pulse current limiting resistor 8 is connected in series with the inverting pulse output switch tube 9 and then grounded (one end of the inverting pulse current limiting resistor 8 is connected to the DC power supply 5, and the other end is connected to the drain of the MOSFET field effect tube, the source of the MOSFET field effect tube is grounded, and the gate of the MOSFET field effect tube is connected to the control signal output end of the dual-path pulse driver 2), and the node of the inverting pulse current limiting resistor 8 and the inverting pulse output switch tube 9 is connected in series through the inverting pulse energy storage capacitor 10 and the inverting pulse discharge resistor 11 and then grounded, and the two ends of the inverting pulse discharge resistor 11 are connected to the other input end of the pulse transformer 6 as the output end of the positive polarity pulse generating circuit.

[0048] The CPLD control circuit 1 controls the output voltage of the DC power supply 5. The DC power supply 5 charges the positive phase pulse energy storage capacitor 14 and the negative phase pulse energy storage capacitor 10 through the positive phase pulse current limiting resistor 12 and the negative phase pulse current limiting resistor 8 respectively, so as to adjust the output pulse waveform amplitude.

[0049] The pulse transformer 6 includes a transformer 18, a DC blocking capacitor 16 and a terminal load resistor 17; the primary side of the transformer 18 is connected to the two signal output terminals of the dual-path strobe pulse generating circuit 3, the secondary side of the transformer 18 is connected in parallel with the terminal load resistor 17, the node of the terminal load resistor 17 and the same-name end of the secondary side of the transformer 18 is connected to one end of the DC blocking capacitor 16, and the other end of the DC blocking capacitor 16 serves as the signal output terminal of the pulse transformer 6. Since the pulse transformer 6 has the characteristics of polarity conversion and impedance matching, the fault type selection function and the standard pulse square wave output are realized.

[0050] In a specific implementation, the positive polarity pulse generating circuit or the negative polarity pulse generating circuit is selected to work according to the set fault type. For example, when the open circuit fault mode is selected, the voltage U 0 The positive phase pulse energy storage capacitor 14 is charged through the positive phase pulse current limiting resistor 12, and the pulse drive signal controls the positive phase pulse output switch tube 13 to turn on. The positive phase pulse energy storage capacitor 14 is discharged through the positive phase pulse discharge resistor 15, and a negative polarity pulse waveform is generated at both ends of the resistor. The positive phase pulse discharge resistor 15 is reversely connected to the pulse transformer 6 to generate a positive polarity pulse waveform, and finally sent to the cable fault flash detector 7 through the terminal load resistor 17 and the DC blocking capacitor 16. Similarly, when the low resistance or short circuit fault mode is selected, the reverse phase discharge resistor 11 is positively connected to the pulse transformer to generate a negative polarity pulse waveform, and finally sent to the cable fault flash detector 7 through the terminal load resistor 17 and the DC blocking capacitor 16.

[0051] According to the formula l=v*Δt / 2, it is calculated that the fault distance l is set to determine the delay time Δt required for sending the reflected pulse waveform. The CPLD control circuit 1 designs a high-precision counter to delay the sending of the reflected pulse drive waveform to one of the dual-channel pulse drivers 2 to send a pulse signal. The dual-channel pulse driver 2 drives the dual-channel selection pulse generating circuit 3 to generate a pulse signal of corresponding polarity, thereby realizing arbitrary adjustment of the fault distance.

[0052] The dual-path selection pulse generating circuit 3 sends a pulse waveform to the pulse transformer 6 for load matching. The pulse transformer 6 finally sends a reflected pulse waveform to the cable fault flash detector 7. The pulse width is consistent with the pulse waveform sent by the cable fault flash detector 7.

[0053] The embodiment of the present invention further provides a method for evaluating the performance of a cable fault flash detector, which is performed using the above-mentioned evaluation device, and the method comprises the following steps:

[0054] The pulse transformer 6 receives the incident pulse output by the cable fault flash detector 7 and sends it to the pulse width detection circuit 4;

[0055] The pulse width detection circuit 4 detects the pulse signal and generates a trigger level, and sends it to the CPLD control circuit 1;

[0056] The CPLD control circuit 1 obtains a pulse trigger signal and a pulse width signal of the incident pulse according to the trigger level detected by the pulse width detection circuit 4, outputs a pulse control signal with a pulse width the same as the incident pulse and a delay time starting from the edge of the pulse trigger signal, and selects one of the dual-channel pulse drivers 2 to output the pulse control signal according to different fault types set by the software;

[0057] The dual-channel strobe pulse generating circuit 3 enables the corresponding positive polarity pulse generating circuit or negative polarity pulse generating circuit to work under the control of the pulse control signal output by the dual-channel pulse driver 2, thereby generating a reflection pulse signal of corresponding polarity;

[0058] The pulse transformer 6 performs impedance matching and polarity change on the reflected pulse signal generated by the dual-path gate pulse generating circuit 3, converts it into a reflected pulse square wave signal and sends it to the cable fault flash detector 7;

[0059] The flash tester 7 detects the reflected pulse square wave signal and calculates the fault distance, compares it with the fault distance set by the cable fault flash tester performance evaluation device, and calculates the error, thereby realizing the performance evaluation of the flash tester.

[0060] Wherein, the CPLD control circuit 1 adjusts the voltage amplitude of the DC power supply 5 and outputs it to the power supply end of the positive polarity pulse generating circuit or the negative polarity pulse generating circuit in the dual-path gate pulse generating circuit 3 to adjust the waveform amplitude of the output reflected pulse;

[0061] The pulse width of the reflected pulse waveform sent by the pulse transformer 6 to the cable fault flash detector 7 is consistent with the width of the pulse waveform sent by the cable fault flash detector 7.

[0062] Figure 5 This is an actual test waveform of a performance evaluation device for a cable fault flash tester of the present invention, wherein traveling wave 1 is an incident pulse waveform generated by the flash tester, and traveling wave 2 is a reflected pulse square wave generated by the device of the present invention. Waveform a is a positive polarity pulse square wave generated by an open circuit fault as a reflected waveform, and waveform b is a negative polarity pulse square wave generated by a low resistance or short circuit fault as a reflected waveform. The rising and falling edge times of the reflected pulse square wave generated by the present invention are within 10ns, and the pulse waveform is close to an ideal square wave.

[0063] The present invention has the following advantages: the method can adaptively adjust the pulse width according to the incident traveling wave, the pulse polarity can be switched, the terminal load is matched, the pulse amplitude is adjustable, the upper and lower edge times are within 10ns, and it has the characteristics of obvious reflection inflection point and pulse waveform close to ideal square wave, which reduces the measurement error caused by unclear inflection point mutation.

[0064] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A cable fault flash detector performance evaluation device, characterized in that: It includes a CPLD control circuit (1), a dual-channel pulse driver (2), a dual-channel strobe pulse generating circuit (3), a pulse width detection circuit (4), and a pulse transformer (6); The signal input end of the pulse transformer (6) is connected to the signal output end of the cable fault flash detector (7), and is used to receive the incident pulse output by the cable fault flash detector (7), and output the incident pulse to the pulse width detection circuit (4); The pulse width detection circuit (4) is connected to the pulse transformer (6) and the CPLD control circuit (1), and is used to receive the incident pulse sent by the pulse transformer (6), detect the pulse signal and generate a trigger level, and send it to the CPLD control circuit (1); The CPLD control circuit (1) is connected to the pulse width detection circuit (4) and is used to obtain a pulse trigger signal and a pulse width signal of the incident pulse according to the trigger level detected by the pulse width detection circuit (4), and output a pulse control signal with a pulse width the same as the incident pulse and a delay time starting from the edge of the pulse trigger signal. The CPLD control circuit (1) is also used to select and control one of the dual-path pulse drivers (2) to output the pulse control signal according to different fault types set by software; The dual-path strobe pulse generating circuit (3) is used to enable the corresponding positive polarity pulse generating circuit or negative polarity pulse generating circuit to operate under the control of the pulse control signal output by the dual-path pulse driver (2), thereby generating a reflection pulse signal of the corresponding polarity; The pulse transformer (6) is used to perform impedance matching and polarity change on the reflected pulse signal generated by the dual-path gate pulse generating circuit (3), convert it into a reflected pulse square wave signal and send it to the cable fault flash detector (7). The cable fault flash detector (7) detects the reflected pulse square wave signal and calculates the fault distance, compares it with the fault distance set by the cable fault flash detector performance evaluation device, and calculates the error, thereby realizing the performance evaluation of the flash detector; It also includes a DC power supply (5) connected to the CPLD control circuit (1) and the dual-path strobe pulse generating circuit (3), wherein the CPLD control circuit (1) is further used to adjust the voltage amplitude of the DC power supply (5) and output it to the power supply end of the positive polarity pulse generating circuit or the negative polarity pulse generating circuit in the dual-path strobe pulse generating circuit (3) to adjust the waveform amplitude of the output reflected pulse; The pulse transformer (6) comprises a transformer (18), a DC blocking capacitor (16) and a terminal load resistor (17); the primary side of the transformer (18) is connected to the signal output end of the dual-path strobe pulse generating circuit (3), the secondary side of the transformer (18) is connected in parallel with the terminal load resistor (17), the node of the same-name end of the terminal load resistor (17) and the secondary side of the transformer (18) is connected to one end of the DC blocking capacitor (16), and the other end of the DC blocking capacitor (16) serves as the signal output end of the pulse transformer (6).

2. A cable fault flash detector performance evaluation device according to claim 1, characterized in that: The dual-path gate pulse generating circuit (3) comprises a positive polarity pulse generating circuit and a negative polarity pulse generating circuit, wherein the positive polarity pulse generating circuit comprises a positive phase pulse current limiting resistor (12), a positive phase pulse output switching tube (13), a positive phase pulse energy storage capacitor (14), and a positive phase pulse discharge resistor (15), and the negative polarity pulse generating circuit comprises a reverse phase pulse current limiting resistor (8), a reverse phase pulse output switching tube (9), a reverse phase pulse energy storage capacitor (10), and a reverse phase pulse discharge resistor (11); the control signal output end of the dual-path pulse driver (2) is connected to the control ends of the positive phase pulse output switching tube (13) and the reverse phase pulse output switching tube (9).

3. A cable fault flash detector performance evaluation device according to claim 2, characterized in that: The voltage U0 output by the DC power supply (5) is connected in series with the positive phase pulse output switch tube (13) through the positive phase pulse current limiting resistor (12) and then grounded; the node between the positive phase pulse current limiting resistor (12) and the positive phase pulse output switch tube (13) is connected in series with the positive phase pulse energy storage capacitor (14) and the positive phase pulse discharge resistor (15) and then grounded; and both ends of the positive phase pulse discharge resistor (15) are connected to an input end of the pulse transformer (6) as the output ends of the negative polarity pulse generating circuit; The voltage U0 output by the DC power supply (5) is connected in series with the inverted pulse output switch tube (9) through the inverted pulse current limiting resistor (8) and then grounded. The node between the inverted pulse current limiting resistor (8) and the inverted pulse output switch tube (9) is connected in series with the inverted pulse energy storage capacitor (10) and the inverted pulse discharge resistor (11) and then grounded. The two ends of the inverted pulse discharge resistor (11) are connected as the output ends of the positive polarity pulse generating circuit to the other input end of the pulse transformer (6).

4. A cable fault flash detector performance evaluation device according to claim 3, characterized in that: The positive-phase pulse output switch tube (13) and the negative-phase pulse output switch tube (9) are both MOSFET field effect tubes. One end of the positive-phase pulse current limiting resistor (12) is connected to the DC power supply (5), and the other end is connected to the drain of the MOSFET field effect tube. The source of the MOSFET field effect tube is grounded. The gate of the MOSFET field effect tube is connected to the control signal output end of the dual-path pulse driver (2). One end of the negative-phase pulse current limiting resistor (8) is connected to the DC power supply (5), and the other end is connected to the drain of the MOSFET field effect tube. The source of the MOSFET field effect tube is grounded. The gate of the MOSFET field effect tube is connected to the control signal output end of the dual-path pulse driver (2).

5. A cable fault flash detector performance evaluation device according to claim 1, characterized in that: The pulse width detection circuit (4) is a high-speed voltage comparator.

6. A method for evaluating the performance of a cable fault flash detector, characterized in that The method is carried out using the evaluation device according to any one of claims 1 to 5, and comprises the following steps: The pulse transformer (6) receives the incident pulse output by the cable fault flash detector (7) and sends it to the pulse width detection circuit (4); The pulse width detection circuit (4) detects the pulse signal and generates a trigger level, and sends it to the CPLD control circuit (1); The CPLD control circuit (1) obtains a pulse trigger signal and a pulse width signal of the incident pulse according to the trigger level detected by the pulse width detection circuit (4), outputs a pulse control signal with a pulse width the same as the incident pulse and a delay time starting from the edge of the pulse trigger signal, and selects one of the dual-path pulse drivers (2) to output the pulse control signal according to different fault types set by software; The dual-path strobe pulse generating circuit (3) enables the corresponding positive polarity pulse generating circuit or negative polarity pulse generating circuit to operate under the control of the pulse control signal output by the dual-path pulse driver (2), thereby generating a reflection pulse signal of the corresponding polarity; The pulse transformer (6) performs impedance matching and polarity change on the reflected pulse signal generated by the dual-path gate pulse generating circuit (3), converts it into a reflected pulse square wave signal and sends it to the cable fault flash detector (7); The cable fault flash detector (7) detects the reflected pulse square wave signal and calculates the fault distance, compares it with the fault distance set by the cable fault flash detector performance evaluation device, and calculates the error, thereby realizing the performance evaluation of the flash detector.

7. A cable fault flash detector performance evaluation method according to claim 6, characterized in that: The CPLD control circuit (1) adjusts the voltage amplitude of the DC power supply (5) and outputs it to the power supply end of the positive polarity pulse generating circuit or the negative polarity pulse generating circuit in the dual-path gate pulse generating circuit (3), so as to adjust the waveform amplitude of the output reflected pulse.

8. A cable fault flash detector performance evaluation method according to claim 6, characterized in that: The pulse width of the reflected pulse waveform sent by the pulse transformer (6) to the cable fault flash detector (7) is consistent with the width of the pulse waveform sent by the cable fault flash detector (7).

Images