A cable partial discharge detector based on ultrasonic technology

Abstract

The present invention relates to a cable partial discharge detector based on ultrasonic technology, comprising: a clamping assembly, an ultrasonic sensor and a data processing device; the clamping assembly comprises: a housing cavity for accommodating an ultrasonic sensor and a clamp for clamping and fixing a cable, the opening of the housing cavity faces the center of the clamp, and the ultrasonic sensor is arranged in the housing cavity; the transmitting window of the ultrasonic sensor faces the center of the clamp, and is used to send ultrasonic waves to the cable, receive reflected waves of the ultrasonic waves reflected by the cable, and output a detection signal to the data processing device; the data processing device is used to generate a discharge detection result of the cable based on the detection signal. The present application can effectively improve the detection accuracy of partial discharge of the cable, and there is no need for manual measurement of height testing, which improves work efficiency, and can reduce the probability of staff being injured by falling from a height, accidentally touching a high-voltage electric potential, etc. during the height testing, thereby ensuring the safety of the experimenters and the test equipment.

Description

Technical Field

[0001] The present application relates to the field of electronic technology, and in particular to a cable partial discharge detector based on ultrasonic technology. Background Art

[0002] Today's society cannot do without electricity, and there are various safety hazards in the operation of power equipment. With the continuous popularization and development of cable manufacturing technology in the new era, most cable manufacturers in my country are able to effectively control the quality of cable products. Therefore, in the absence of external destructive factors, the probability of defects and failures in power cables due to intrinsic factors is relatively low.

[0003] The cable intermediate joints and terminals have a relatively complex structure, and therefore require a higher level of installation technology. During the on-site installation of power cables, they will be affected by factors such as the surrounding environmental conditions and the installation personnel's technology level. Therefore, the insulation quality of the installed cables is relatively low. In the later long-term operation process, it is easy to cause various faults and accidents due to these potential problem factors, such as partial discharge.

[0004] Partial discharge (PD) is the main manifestation of cable insulation failure in the early stage. It is one of the main causes of insulation degradation. If the partial discharge problem cannot be handled in time, the equipment will continue to operate with power, which will cause safety hazards. Therefore, power industry workers attach great importance to the monitoring of partial discharge. Summary of the invention

[0005] In order to solve the above technical problem or at least partially solve the above technical problem, the present application provides a cable partial discharge detector based on ultrasonic technology.

[0006] In a first aspect, the present application provides a cable partial discharge detector based on ultrasonic technology, comprising: a clamping assembly, an ultrasonic sensor and a data processing device;

[0007] The clamping assembly comprises: a housing cavity for accommodating the ultrasonic sensor and a clamp for clamping and fixing the cable, the opening of the housing cavity faces the center of the clamp, and the ultrasonic sensor is arranged in the housing cavity;

[0008] The transmitting window of the ultrasonic sensor faces the center of the clamp, and is used to send ultrasonic waves to the cable, receive reflected waves of the ultrasonic waves reflected by the cable, and output a detection signal to the data processing device;

[0009] The data processing device is used to generate a discharge detection result of the cable based on the detection signal.

[0010] Optionally, the clamping assembly further comprises: a spring screw and a baffle disposed between the spring screw and the ultrasonic sensor;

[0011] The threaded end of the spring screw is threadedly fixed to the blocking piece, and a bottom surface of the accommodating cavity opposite to the opening is provided with an opening for allowing a nut of the spring screw to extend out.

[0012] Optionally, the spring screw comprises a spring and a bolt;

[0013] The bottom of the bolt is provided with a thread, and the top is provided with a nut. The spring is sleeved on the screw rod and fixed to the bottom of the nut.

[0014] Optionally, the clamp is in a circular ring shape, and the shape of the inner wall of the clamp is adapted to the shape of the cable.

[0015] Optionally, a buckle is provided on the clamp for fastening the clamp.

[0016] Optionally, the data processing device includes: a signal processing module and a processor;

[0017] The signal processing module is used to perform signal processing on the detection signal to obtain a voltage signal;

[0018] The processor is used to generate the discharge detection result based on the voltage signal.

[0019] Optionally, the signal processing module includes: a preamplifier unit;

[0020] The preamplifier unit is connected to the output end of the ultrasonic sensor and is used to amplify the detection signal and output the amplified detection signal.

[0021] Optionally, the signal processing module further includes: a filtering unit;

[0022] The filtering unit is connected to the output end of the pre-amplifying unit, and is used for filtering the amplified detection signal and outputting the filtered detection signal.

[0023] Optionally, the signal processing module further includes: an A / D conversion unit;

[0024] The A / D conversion unit is connected to the output end of the filtering unit and is used to perform A / D conversion on the filtered detection signal to obtain a digital detection signal as an input of the processor.

[0025] Optionally, the data processing device is also connected to an external PC for communication, and sends the detection signal and the discharge detection result to the PC for storage.

[0026] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0027] The present application utilizes ultrasonic waves, a byproduct of local discharge, to detect local discharge, thereby effectively improving the detection accuracy of local discharge of cables. In addition, the application eliminates the need for manual measurement of height tests, thereby improving work efficiency. Furthermore, the probability of workers being injured by falling from heights or accidentally touching high-voltage objects during height tests can be reduced, thereby ensuring the safety of experimenters and test equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0030] Figure 1 A partial structural diagram of a cable partial discharge detector based on ultrasonic technology provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of the principle of a cable partial discharge detector based on ultrasonic technology provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0033] like Figure 1 and Figure 2 As shown, the present application embodiment provides a cable partial discharge detector based on ultrasonic technology, including: a clamping component, an ultrasonic sensor 1 (see Figure 1 ) and data processing equipment;

[0034] The clamping assembly comprises: a housing cavity 5 for housing the ultrasonic sensor 1 and a clamp 6 for clamping and fixing the cable, the opening of the housing cavity 5 faces the center of the clamp 6, and the ultrasonic sensor 1 is arranged in the housing cavity 5;

[0035] The clamp 6 is in a circular ring shape, and the shape of the inner wall of the clamp 6 is adapted to the shape of the cable. A buckle is provided on the clamp 6 for fastening the clamp 6 .

[0036] The clamping assembly further includes: a spring screw and a baffle 2 disposed between the spring screw and the ultrasonic sensor 1;

[0037] The threaded end of the spring screw is threadedly fixed to the blocking piece 2, and the bottom surface of the accommodating cavity 5 opposite to the opening is provided with an opening for allowing the nut of the spring screw to extend out.

[0038] The spring screw comprises a spring 4 and a bolt 3;

[0039] The bottom of the bolt 3 is provided with a thread, and the top is provided with a nut. The spring 4 is sleeved on the screw and fixed to the bottom of the nut.

[0040] like Figure 1 As shown, the clamping assembly consists of a metal shell (i.e., the outer wall of the accommodating cavity), a spring 4, a stainless steel clamp 6 and a bolt 3. When no detection is required, the bolt 3 fits tightly against the metal shell, and the spring 4 is in a relaxed state. When the sensor contacts the cable, the spring 4 is deformed by pressure, and the nut of the bolt 3 protrudes. The stainless steel clamp 6 is used to tie the ultrasonic sensor 1 to the cable to minimize the propagation loss.

[0041] The transmitting window of the ultrasonic sensor 1 faces the center of the clamp 6, and is used to send ultrasonic waves to the cable, receive reflected waves of the ultrasonic waves reflected by the cable, and output a detection signal to the data processing device;

[0042] The ultrasonic signal formed by partial discharge is extremely weak, and its energy is generally at the μJ level. During the detection process, the signal must be amplified by a preamplifier. Since the acoustic signal is not easy to amplify, it is necessary to use a sensor with piezoelectric effect for sound-to-electric conversion. The piezoelectric element material in the sensor usually uses polycrystalline materials such as lead zirconate titanate, lead titanate, barium titanate, or single crystals such as lithium titanate and lithium iodate. Among them, lead zirconate titanate has high sensitivity and is the most commonly used piezoelectric material. The sensors used in ultrasonic partial discharge detection include single-ended sensors and differential sensors.

[0043] The data processing device is used to generate a discharge detection result of the cable based on the detection signal.

[0044] The data processing device comprises: a signal processing module and a processor;

[0045] The signal processing module is used to perform signal processing on the detection signal to obtain a voltage signal;

[0046] The processor is used to generate the discharge detection result based on the voltage signal.

[0047] like Figure 2 As shown, the signal processing module includes: a preamplifier unit;

[0048] The preamplifier unit is connected to the output end of the ultrasonic sensor 1 and is used to amplify the detection signal and output the amplified detection signal.

[0049] The preamplifier unit uses a precision operational amplifier to amplify the signal generated by the ultrasonic sensor 1. The signal obtained by the ultrasonic sensor 1 is a small differential signal with some common-mode components. Therefore, the amplifier should have a strong ability to suppress common-mode signals. The precision operational amplifier has the characteristics of high amplification, high input impedance and high common-mode rejection ratio. The preamplifier circuit formed by it is suitable for amplifying the output voltage signal of the ultrasonic sensor 1. As a first-stage amplifier circuit, the circuit can be amplified by one time.

[0050] The signal processing module further includes: a filtering unit;

[0051] The filtering unit is connected to the output end of the pre-amplifying unit, and is used for filtering the amplified detection signal and outputting the filtered detection signal.

[0052] The filter unit can use an operational amplifier to construct an active filter. Usually, active filter circuits are named according to their operating frequency bands and can be divided into low-pass filters, high-pass filters, band-pass filters, stop-band filters, and all-pass filters. According to the system filter circuit structure and index performance, choosing a suitable method to calculate the parameters of the filter circuits at all levels is a very critical step in filter design. The amplitude-frequency response function of the ideal filter is a mutation function, which is difficult to achieve. Its characteristics can only be approximated by a high-order filter network that can be realized by a physical circuit. Commonly used approximation functions include Butterworth, Chebyshev, Bessel, etc., but the amplitude-frequency response and transient response characteristics of these filters are quite different. According to the characteristics of the ultrasonic signal generated by the partial discharge signal, here we use the Bessel bandpass filter, the low-frequency cutoff frequency is selected as 40kHz, the high-frequency cutoff frequency is selected as 200kHz, and the gain is set to about 10, so as to further amplify the signal. In this way, a voltage signal with a frequency between 40 and 200kHz can be obtained. After the action of the filter circuit, the mechanical motion noise, the electric pulses generated by the corona, and the strong electromagnetic induction interference signal are effectively filtered out.

[0053] The signal processing module also includes: an A / D conversion unit;

[0054] The A / D conversion unit is connected to the output end of the filtering unit and is used to perform A / D conversion on the filtered detection signal to obtain a digital detection signal as an input of the processor.

[0055] In order to be able to perform subsequent processing on the obtained partial discharge signal, it is necessary to convert the analog signal into a digital signal, and pass the electric signal obtained after filtering through an A / D converter, and the conversion accuracy is selected according to actual needs. The embodiment of the present application adopts an integrated data acquisition module. According to the sampling law, the sampling frequency ω must be greater than twice the cutoff rate of the band-limited signal, that is, 2ω. The subsequent processing of the signal is mainly carried out by computer software. At the same time, relevant software programs are written to identify the amplitude and phase of the discharge signal, thereby providing a basis for the decision-making system to judge the strength and insulation state of the partial discharge signal of the internal insulation of the cable terminal.

[0056] The present application utilizes ultrasonic waves, a byproduct of local discharge, to detect local discharge, thereby effectively improving the detection accuracy of local discharge of cables. In addition, the application eliminates the need for manual measurement of height tests, thereby improving work efficiency. Furthermore, the probability of workers being injured by falling from heights or accidentally touching high-voltage objects during height tests can be reduced, thereby ensuring the safety of experimenters and test equipment.

[0057] The data processing device is also connected to an external PC for communication, and sends the detection signal and the discharge detection result to the PC for storage.

[0058] In order to detect whether partial discharge has occurred in real time, this application also built a PC acquisition software design. The platform mainly has three coordinates representing three indexes, x phase, y time, and z assignment. The waveform at that time is recorded every minute and compared with the partial discharge waveform. Once partial discharge occurs, the location of the discharge point is determined in time. The collected data is sorted and stored in the database. If partial discharge occurs, the discharge type can be determined.

[0059] This device adopts ultrasonic online monitoring method. The ultrasonic signal propagates from the internal discharge point through the insulating layer to the outer surface. The acoustic emission sensor can convert the raw signal into an electrical signal for signal processing and diagnosis. The cable accessory terminal external partial discharge monitoring device studied in this project can obtain the partial discharge monitoring signal by collecting the ultrasonic signal of partial discharge, and then obtain the partial discharge monitoring signal through pre-amplification and filtering. After A / D conversion, the analog signal can be converted into a digital signal and transmitted to the signal processing unit. The processing unit processes the data according to the edge computing method, and finally uploads it to the software analysis background to display the monitoring data information online in real time, and issue early warnings through the set alarm strategy.

[0060] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0061] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A cable partial discharge detector based on ultrasonic technology, characterized in that: include: Clamping assembly, ultrasonic sensor and data processing device; The clamping assembly comprises: a housing cavity for accommodating the ultrasonic sensor and a clamp for clamping and fixing the cable, the opening of the housing cavity faces the center of the clamp, and the ultrasonic sensor is arranged in the housing cavity; The clamping assembly further includes: a spring screw and a baffle disposed between the spring screw and the ultrasonic sensor; The threaded end of the spring screw is threadedly fixed to the blocking piece, and the bottom surface of the accommodating cavity opposite to the opening is provided with an opening for the nut of the spring screw to extend out; The spring screw comprises a spring and a bolt; The bottom of the bolt is provided with a thread, and the top is provided with a nut, and the spring is sleeved on the screw and fixed to the bottom of the nut; The transmitting window of the ultrasonic sensor faces the center of the clamp, and is used to send ultrasonic waves to the cable, receive reflected waves of the ultrasonic waves reflected by the cable, and output a detection signal to the data processing device; The data processing device is used to generate a discharge detection result of the cable based on the detection signal.

2. The cable partial discharge detector according to claim 1, characterized in that: The clamp is in a circular ring shape, and the shape of the inner wall of the clamp is adapted to the shape of the cable.

3. The cable partial discharge detector according to claim 1, characterized in that: The clamp is provided with a buckle for fastening the clamp.

4. The cable partial discharge detector according to claim 1, characterized in that: The data processing device comprises: a signal processing module and a processor; The signal processing module is used to perform signal processing on the detection signal to obtain a voltage signal; The processor is used to generate the discharge detection result based on the voltage signal.

5. The cable partial discharge detector according to claim 4, characterized in that: The signal processing module includes: a preamplifier unit; The preamplifier unit is connected to the output end of the ultrasonic sensor and is used to amplify the detection signal and output the amplified detection signal.

6. The cable partial discharge detector according to claim 5, characterized in that: The signal processing module further includes: a filtering unit; The filtering unit is connected to the output end of the pre-amplifying unit, and is used for filtering the amplified detection signal and outputting the filtered detection signal.

7. The cable partial discharge detector according to claim 6, characterized in that: The signal processing module also includes: an A / D conversion unit; The A / D conversion unit is connected to the output end of the filtering unit and is used to perform A / D conversion on the filtered detection signal to obtain a digital detection signal as an input of the processor.

8. The cable partial discharge detector according to claim 1, characterized in that: The data processing device is also connected to an external PC for communication, and sends the detection signal and the discharge detection result to the PC for storage.

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