CN103513158A - Damped oscillatory wave lower cable local discharge detection device and method - Google Patents
Damped oscillatory wave lower cable local discharge detection device and method Download PDFInfo
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Abstract
本发明公开了一种阻尼振荡波电压下电缆局部放电检测装置及检测方法。包括：信号耦合单元和宽频带放大单元；所述信号耦合单元包括检测阻抗和耦合电容，检测阻抗的一端与耦合电容的低压侧连接，另一端接地；所述宽频带放大单元包括衰减器，衰减器驱动电路，锁存器以及放大器。信号耦合单元耦合局部放电的原始信号以及在电缆端部的反射信号。耦合的局放信号在放大器适当的放大倍数下，并通过其有效频带，然后经过滤波去除大量干扰信号和背景噪声，充分提高局放信号的信噪比。最后将放大信号送到采集卡输入端，以供数字仪器对局放信号的处理。The invention discloses a cable partial discharge detection device and a detection method under damped oscillatory wave voltage. Including: a signal coupling unit and a broadband amplification unit; the signal coupling unit includes a detection impedance and a coupling capacitor, one end of the detection impedance is connected to the low-voltage side of the coupling capacitor, and the other end is grounded; the broadband amplification unit includes an attenuator, attenuating driver circuits, latches, and amplifiers. The signal coupling unit couples the original signal of the partial discharge and the reflected signal at the end of the cable. The coupled partial discharge signal passes through its effective frequency band under the appropriate amplification factor of the amplifier, and then is filtered to remove a large number of interference signals and background noise, so as to fully improve the signal-to-noise ratio of the partial discharge signal. Finally, the amplified signal is sent to the input terminal of the acquisition card for the digital instrument to process the partial discharge signal.
Description
技术领域technical field
本发明涉及交联聚乙烯电缆（XLPE）的一种局部放电在线检测方法，特别是一种阻尼振荡波下电缆局部放电检测装置及检测方法。The invention relates to an on-line partial discharge detection method of a cross-linked polyethylene cable (XLPE), in particular to a cable partial discharge detection device and detection method under damped oscillatory waves.
背景技术Background technique
交联聚乙烯电缆以其合理的结构、工艺以及优良的电气性能以及较高的安全性等优点，在国内外输电线路及配电网中广泛使用。但电缆在生产，运输，安装以及运行过程中，可能会产生气隙、毛刺以及杂质等各种缺陷。存在缺陷或长期运行导致劣化后的电缆容易发生局部放电，在长时间的局部放电作用下，进一步会导致电缆绝缘的击穿，一旦发生事故，有可能会使城市大面积停电、企业停产、医院断电，从而造成较大的经济损失及人身安全等，因此有必要对电缆在投运前和运行后进行局部放电试验。XLPE cables are widely used in transmission lines and distribution networks at home and abroad due to their reasonable structure, technology, excellent electrical performance and high safety. However, during the production, transportation, installation and operation of cables, various defects such as air gaps, burrs and impurities may occur. Defects or long-term operation lead to deterioration of cables prone to partial discharge. Under the action of long-term partial discharge, it will further lead to breakdown of cable insulation. Once an accident occurs, it may cause large-scale power outages in cities, stop production of enterprises, and hospitals. Power failure will cause large economic losses and personal safety, etc. Therefore, it is necessary to conduct partial discharge tests on cables before and after operation.
局部放电试验一直是电缆绝缘非破坏性电气检验的主要项目。迄今为止，国内外用于XLPE电缆及其附件局部放电检测的方法有很多。但由于XLPE电缆及其附件中局部放电信号微弱，波形复杂多变，在传统的测量中极易被背景噪声和外界电磁干扰噪声淹没，在现场测量中，环境干扰更复杂，难度会更大。世界各国专业人士纷纷致力于高灵敏度的局部放电检测仪器的开发来对电缆绝缘进行局部放电的检测。Partial discharge test has always been the main item of non-destructive electrical inspection of cable insulation. So far, there are many methods for partial discharge detection of XLPE cables and their accessories at home and abroad. However, because the partial discharge signal in the XLPE cable and its accessories is weak and the waveform is complex and changeable, it is easily overwhelmed by the background noise and external electromagnetic interference noise in the traditional measurement. In the field measurement, the environmental interference is more complicated and the difficulty will be greater. Professionals from all over the world are devoting themselves to the development of highly sensitive partial discharge detection instruments to detect partial discharge of cable insulation.
随着电子技术的发展，在传统的脉冲电流法的基础上发展了基于宽频带检测技术，应用数字信号处理方法进行抗干扰、定位和谱图分析的计算机辅助的局部放电测量技术，大大推动了电缆局部放电测量技术的发展。振荡波局放检测装置作为一种新型的较方便的电缆现场局放检测和定位方式，具有与交流电源法等效性好、作用时间短、操作方便、易于携带、可有效检测XLPE电缆中的各种缺陷，且试验不会对电缆造成损害等特点。但在现场测量中，如果缺陷微小或外界干扰较大，都使局放检测及定位难度大大加大，因此在现场局部放电检测中，信号的有效提取和放大是亟待完成的难点之一。With the development of electronic technology, on the basis of the traditional pulse current method, a computer-aided partial discharge measurement technology based on broadband detection technology and digital signal processing method for anti-interference, positioning and spectrum analysis has been developed, which has greatly promoted Development of cable partial discharge measurement technology. As a new and more convenient on-site partial discharge detection and positioning method for cables, the oscillatory wave partial discharge detection device has the advantages of good equivalence with the AC power method, short action time, convenient operation, easy to carry, and can effectively detect the partial discharge in XLPE cables. Various defects, and the test will not cause damage to the cable and so on. However, in the on-site measurement, if the defect is small or the external interference is large, it will greatly increase the difficulty of PD detection and positioning. Therefore, in the on-site partial discharge detection, the effective extraction and amplification of the signal is one of the difficulties that need to be completed urgently.
发明内容Contents of the invention
本发明针对目前电缆局部放电现场检测的灵敏度不高问题，提供一种阻尼振荡波下电缆局部放电检测装置及检测方法来有效提高局放信号检测的灵敏度及信噪比。Aiming at the problem of low sensitivity of cable partial discharge on-site detection at present, the invention provides a cable partial discharge detection device and detection method under damped oscillation waves to effectively improve the sensitivity and signal-to-noise ratio of partial discharge signal detection.
为实现上述目的，本发明采用以下技术方案：To achieve the above object, the present invention adopts the following technical solutions:
一种阻尼振荡波下电缆局部放电检测装置，包括：信号耦合单元和宽频带放大单元；所述信号耦合单元包括检测阻抗和耦合电容，检测阻抗的一端与耦合电容的低压侧连接，另一端接地，所述耦合电容的高压侧与高压电源相连；所述宽频带放大单元包括衰减器，衰减器驱动电路，锁存器以及放大器，所述信号耦合单元的输出与衰减器的输入相连，所述衰减器的输出与放大器相连，所述衰减器驱动电路的输入与锁存器的输出相连，所述锁存器的输入与上位机的输出相连。A cable partial discharge detection device under damped oscillating waves, comprising: a signal coupling unit and a broadband amplification unit; the signal coupling unit includes a detection impedance and a coupling capacitor, one end of the detection impedance is connected to the low-voltage side of the coupling capacitor, and the other end is grounded , the high-voltage side of the coupling capacitor is connected to the high-voltage power supply; the broadband amplifying unit includes an attenuator, an attenuator driving circuit, a latch and an amplifier, the output of the signal coupling unit is connected to the input of the attenuator, and the The output of the attenuator is connected with the amplifier, the input of the drive circuit of the attenuator is connected with the output of the latch, and the input of the latch is connected with the output of the host computer.
作为本发明的优选实施例，所述信号耦合单元进一步包括有隔离变压器，检测阻抗、耦合电容，以及隔离变压器形成RLC型耦合回路。As a preferred embodiment of the present invention, the signal coupling unit further includes an isolation transformer, and the detection impedance, the coupling capacitor, and the isolation transformer form an RLC coupling loop.
作为本发明的优选实施例，所述信号耦合单元进一步包括保险丝、二极管，以及滤波电容，所述检测阻抗的输出端依次连接所述保险丝和所述滤波电容，所述检测阻抗的两端并接所述二级管。As a preferred embodiment of the present invention, the signal coupling unit further includes a fuse, a diode, and a filter capacitor, the output end of the detection impedance is connected to the fuse and the filter capacitor in turn, and the two ends of the detection impedance are connected in parallel the second tube.
作为本发明的优选实施例，所述衰减器主要由阻、容衰减器和继电器构成，由上位机程控实现衰减倍数的改变。As a preferred embodiment of the present invention, the attenuator is mainly composed of resistance and capacitance attenuators and relays, and the attenuation factor is changed by the program control of the host computer.
作为本发明的优选实施例，所述放大器采用三级差分放大，单端输入，单端输出，以减小共模干扰。As a preferred embodiment of the present invention, the amplifier adopts three-stage differential amplification, single-end input and single-end output, so as to reduce common-mode interference.
作为本发明的优选实施例，所述三级放大器的放大倍数前级大，后级小。As a preferred embodiment of the present invention, the amplification factor of the three-stage amplifier is large at the front stage and small at the rear stage.
作为本发明的优选实施例，所述放大器的输入信号限幅为1mV～8V，输出信号限幅为5V。As a preferred embodiment of the present invention, the input signal limit of the amplifier is 1mV-8V, and the output signal limit is 5V.
基于上述检测装置的检测方法为：通过信号耦合单元提取阻尼振荡波电压下的电缆局部放电信号，然后将该放电信号传送给宽频带放大器，如果放电信号为小电流信号，则跳过衰减器而直径通过放大器放大，如果该放电信号为大电流，则首先通过衰减器衰减后再通过放大器放大。The detection method based on the above-mentioned detection device is: extract the partial discharge signal of the cable under the damped oscillatory wave voltage through the signal coupling unit, and then transmit the discharge signal to the broadband amplifier. If the discharge signal is a small current signal, skip the attenuator and The diameter is amplified by the amplifier. If the discharge signal is a large current, it will first be attenuated by the attenuator and then amplified by the amplifier.
作为本发明的优选实施例，所述大电流和小电流的判断标准为：如果该电流经由最小倍数的放大器放大后超出了放大器的最大量程，则判断该电路为大电流，反之为小电流As a preferred embodiment of the present invention, the criterion for judging the large current and the small current is: if the current is amplified by the amplifier with the minimum multiple and exceeds the maximum range of the amplifier, then it is judged that the circuit is a large current, otherwise it is a small current
与现有技术相比，本发明装置至少具有以下优点：本发明通过信号耦合单元耦合到电缆中的局部放电信号，然后通过宽频带放大单元对该放电信号进行放大，在信号放大时，上位机根据放大器的输出信号大小，发出相应地切换衰减器的控制信号，从而实现对采集信号的适当放大。Compared with the prior art, the device of the present invention has at least the following advantages: the present invention couples the partial discharge signal in the cable through the signal coupling unit, and then amplifies the discharge signal through the broadband amplifying unit. When the signal is amplified, the upper computer According to the magnitude of the output signal of the amplifier, a control signal for switching the attenuator is issued correspondingly, so as to realize proper amplification of the collected signal.
附图说明Description of drawings
图1为本发明检测阻抗及宽频带放大器的信号耦合单元原理图。Fig. 1 is a schematic diagram of the detection impedance and signal coupling unit of the broadband amplifier of the present invention.
图2为本发明检测阻抗及宽频带放大器的检测阻抗幅频特性响应实验电路图。Fig. 2 is an experimental circuit diagram of the detection impedance and the amplitude-frequency characteristic response of the detection impedance of the broadband amplifier of the present invention.
图3为本发明检测阻抗及宽频带放大器的检测阻抗与Rogowsky线圈的幅频特性对比图。Fig. 3 is a comparison diagram of the detection impedance of the present invention and the detection impedance of the broadband amplifier and the amplitude-frequency characteristic of the Rogowsky coil.
图4为本发明检测阻抗及宽频带放大器的检测阻抗与Rogowsky线圈的脉冲响应对比图，其中图4（a）为检测阻抗所测图，图（b）为Rogowsky线圈所测图。Fig. 4 is a comparison diagram of the detection impedance of the present invention and the detection impedance of the broadband amplifier and the impulse response of the Rogowsky coil, wherein Fig. 4 (a) is a graph measured by the detection impedance, and graph (b) is a graph measured by the Rogowsky coil.
图5为本发明检测阻抗及宽频带放大器的放大单元电路结构示意图。图6为本发明检测阻抗及宽频带放大器的放大单元原理图及PCB图。图7为本发明检测阻抗及宽频带放大器阻尼振荡波局部放电检测系统实验室试验线路图。Fig. 5 is a schematic diagram of the circuit structure of the amplification unit of the detection impedance and broadband amplifier of the present invention. Fig. 6 is a schematic diagram and a PCB diagram of the amplification unit of the detection impedance and broadband amplifier of the present invention. Fig. 7 is a laboratory test circuit diagram of the partial discharge detection system for detection impedance and broadband amplifier damped oscillatory wave of the present invention.
图8为本发明检测阻抗及宽频带放大器实验室阻尼振荡波局部放电检测系统升压至4.5kV电压下的电晕放电谱图。Fig. 8 is the corona discharge spectrogram of the damped oscillatory wave partial discharge detection system in the laboratory of the present invention for detecting impedance and broadband amplifier when the voltage is boosted to 4.5kV.
具体实施方式Detailed ways
本发明提供了一种阻尼振荡波电压下电缆局部放电检测装置，包括信号耦合单元和宽频带放大器。The invention provides a cable partial discharge detection device under damped oscillating wave voltage, which includes a signal coupling unit and a broadband amplifier.
信号耦合单元主要由检测阻抗，保险丝，放电管，滤波电容，隔离变压器组成，其主要作用为提取阻尼振荡波电压下的电缆局部放电信号。其中，所述检测阻抗的一端接地，另外一端通过耦合电容与高压电源连接；所述放电管与检测阻抗并联连接，所述放电管的一端直接与隔离变压器的一端相连，放电管的另外一端通过串联的保险丝和滤波电容连接在隔离变压器的另外一端。检测电路中的检测阻抗与耦合电容和隔离变压器的一次线圈构成RLC型耦合回路，从而耦合局部放电信号。滤波电容C1和一次线圈构成滤波回路，避免测量侧的干扰信号进入后续电路。隔离变压器起到信号的有效传递。该信号耦合单元的另一特点是装有保险丝和放电管，在电流或电压较大时可以有效的保护检测电路。The signal coupling unit is mainly composed of detection impedance, fuse, discharge tube, filter capacitor, and isolation transformer. Its main function is to extract the partial discharge signal of the cable under the damped oscillatory wave voltage. Wherein, one end of the detection impedance is grounded, and the other end is connected to the high-voltage power supply through a coupling capacitor; the discharge tube is connected in parallel with the detection impedance, one end of the discharge tube is directly connected to one end of the isolation transformer, and the other end of the discharge tube is passed through The series fuse and filter capacitor are connected at the other end of the isolation transformer. The detection impedance in the detection circuit, the coupling capacitor and the primary coil of the isolation transformer form an RLC type coupling loop, thereby coupling the partial discharge signal. The filter capacitor C1 and the primary coil form a filter circuit to prevent interference signals from the measurement side from entering subsequent circuits. The isolation transformer plays a role in the effective transmission of signals. Another feature of the signal coupling unit is that it is equipped with a fuse and a discharge tube, which can effectively protect the detection circuit when the current or voltage is large.
本发明中的宽频带放大器单元主要包括衰减器、衰减器驱动电路、锁存器以及放大器。The broadband amplifier unit in the present invention mainly includes an attenuator, an attenuator driving circuit, a latch and an amplifier.
考虑到不同的放电水平，需要不同的放大倍数，放大器具有可变放大倍数：1倍、5倍、10倍、50倍、100倍，500倍。放大器的输入信号限幅为1mV～8V，输出信号限幅为5V。从而当输入或输出较高时，可以起到一定的保护作用。Considering that different discharge levels require different magnifications, the amplifier has variable magnifications: 1x, 5x, 10x, 50x, 100x, 500x. The input signal limit of the amplifier is 1mV ~ 8V, and the output signal limit is 5V. Therefore, when the input or output is high, it can play a certain protective role.
本发明具有较高的放大倍数、较低的本机噪声及较宽的频带响应。根据XLPE电缆现场检测及定位要求，设计了频带为20kHz～15MHz，放大系数可达500倍的检测阻抗及宽频带放大器。The invention has higher amplification factor, lower local noise and wider frequency band response. According to the on-site detection and positioning requirements of XLPE cables, a detection impedance and a broadband amplifier with a frequency band of 20kHz to 15MHz and an amplification factor of up to 500 times are designed.
下面结合附图说明对本发明做进一步详细描述：The present invention will be described in further detail below in conjunction with the accompanying drawings:
1.信号耦合单元1. Signal coupling unit
本发明信号耦合单元（检测阻抗）的主要作用是真实有效的耦合到电缆中的局部放电信号，对试验电压的工频及其谐振的低频信号予以抑制或滤除。因此，检测阻抗对仪器的频率特性与灵敏度有直接关系。The main function of the signal coupling unit (detection impedance) of the present invention is to truly and effectively couple the partial discharge signal in the cable, to suppress or filter out the power frequency of the test voltage and its resonant low frequency signal. Therefore, the detection impedance has a direct relationship to the frequency characteristics and sensitivity of the instrument.
请参阅图1所示，检测阻抗的一端与高压耦合电容的低压侧连接，另一端接地。在检测阻抗的输出端依次连接保险丝、滤波电容以及隔离变压器的一次线圈，并在检测阻抗的两端并接放电管。Please refer to Figure 1, one end of the sense impedance is connected to the low voltage side of the high voltage coupling capacitor, and the other end is grounded. Connect the fuse, the filter capacitor and the primary coil of the isolation transformer in sequence to the output end of the detection impedance, and connect the discharge tube in parallel at both ends of the detection impedance.
高压耦合电容CK为1nF，通过变换不同的阻抗参数来达到最佳的频带响应和较高的灵敏度。检测阻抗的频带响应指的是电压源频率变化时，检测阻抗两端电压UZ（mV）与通过分压电容CK的电流IC（mA）的比值UZ/IC（mV/mA）。当其阻值为2k欧姆时，其频带响应为30kHz～15MHz，且在该频带内响应较平缓，灵敏度相对较高，能够满足该系统局放检测和定位的要求。The high-voltage coupling capacitor C K is 1nF, and the best frequency band response and high sensitivity can be achieved by changing different impedance parameters. The frequency band response of the detection impedance refers to the ratio U Z /I C (mV/mA) of the voltage U Z (mV) across the detection impedance to the current I C (mA) passing through the voltage dividing capacitor CK when the frequency of the voltage source changes . When its resistance value is 2k ohms, its frequency band response is 30kHz ~ 15MHz, and the response in this frequency band is relatively flat, and the sensitivity is relatively high, which can meet the requirements of partial discharge detection and positioning of the system.
本发明的信号耦合单元其他参数如下：滤波电容为0.1uF，隔离变压器采用射频变压器（匝数比为1），保险丝采用30mA的保险丝，放电管采用75V的气体放电管。Other parameters of the signal coupling unit of the present invention are as follows: the filter capacitance is 0.1uF, the isolation transformer adopts a radio frequency transformer (turn ratio is 1), the fuse adopts a 30mA fuse, and the discharge tube adopts a 75V gas discharge tube.
（1）对上述已优化的检测阻抗与以Ni-Zn材料为磁芯的Rogowsky线圈电流传感器进行频带响应对比实验。(1) Conduct frequency band response comparison experiments between the above-mentioned optimized detection impedance and the Rogowsky coil current sensor with Ni-Zn material as the magnetic core.
请参阅图3所示。可知：在频带30kHz～15MHz区间内，相比Rogowsky线圈电流传感器，检测阻抗具有较好的频带响应和较高的灵敏度，可以更好地满足局部放电检测的要求。Please refer to Figure 3. It can be seen that in the frequency range of 30 kHz to 15 MHz, compared with the Rogowsky coil current sensor, the detection impedance has better frequency band response and higher sensitivity, which can better meet the requirements of partial discharge detection.
（2）输入量为50pC方波信号对比试验(2) The input volume is 50pC square wave signal comparison test
请参阅图4所示。当输入量为50pC的方波信号时，可以看出通过检测阻抗所测的脉冲信号为：上升沿时间为t=20ns，幅值为Vp=35mV,测量频率为12.5MHz左右；通过Rogowsky线圈电流传感器所测的脉冲信号为：上升沿时间为t=30ns，幅值为Vp=15mV,测量频率为8.3MHz左右。进一步可以看出，检测阻抗的信号耦合能力要优于Rogowsky线圈电流传感器Please refer to Figure 4. When the input volume is a square wave signal of 50pC, it can be seen that the pulse signal measured by the detection impedance is: the rising edge time is t=20ns, the amplitude is Vp=35mV, and the measurement frequency is about 12.5MHz; through the Rogowsky coil current The pulse signal measured by the sensor is: the rising edge time is t=30ns, the amplitude is Vp=15mV, and the measurement frequency is about 8.3MHz. It can be further seen that the signal coupling ability of the detection impedance is better than that of the Rogowsky coil current sensor
2.宽频带放大器单元2. Broadband Amplifier Unit
本发明的宽频带放大器的电路结构示意图参阅图5及图6所示，主要包括衰减器、衰减器驱动电路、锁存器以及放大器。Refer to FIG. 5 and FIG. 6 for schematic diagrams of the circuit structure of the broadband amplifier of the present invention, which mainly includes an attenuator, an attenuator driving circuit, a latch and an amplifier.
衰减器是为了扩大放大器的适用范围，对小信号不衰减，直接进行放大，而对大信号先进行衰减，然后再进行放大，这样不至于在大信号时，放大器进入饱和状态。放大器的放大倍数是不变的，这样可保持放大器的带宽不变。衰减器主要由阻、容衰减器和继电器构成，由上位机程控实现衰减倍数的改变。衰减倍数分为×1、×5、×10、×50、×100、×500六档。The attenuator is to expand the scope of application of the amplifier. It does not attenuate the small signal and directly amplifies it. It first attenuates the large signal and then amplifies it, so that the amplifier will not enter a saturated state when the signal is large. The magnification of the amplifier is constant, which keeps the bandwidth of the amplifier constant. The attenuator is mainly composed of resistive, capacitive attenuators and relays, and the change of the attenuation multiple is realized by the program control of the host computer. The attenuation multiples are divided into six levels: ×1, ×5, ×10, ×50, ×100, ×500.
衰减器驱动电路是为了保证继电器能够可靠地吸合而加入的，对来自于锁存器的控制信号进行电流放大，增大吸合时继电器线圈中的电流，保证继电器能够可靠地吸合，从而实现衰减器的可靠！The attenuator drive circuit is added to ensure that the relay can be pulled in reliably. It amplifies the current of the control signal from the latch to increase the current in the relay coil during pull-in to ensure that the relay can be pulled in reliably, thus Realize the reliability of the attenuator!
锁存器是为了保存上位机发出的控制信号，在本发明中采用的是锁存器SN74HC573A。上位机根据放大器输出信号的大小，发出的相应地切换衰减器的控制信号，上位机只需发出一次控制信号，锁存器就可将其锁存，保持衰减器的衰减倍数不变，除非上位机要切换衰减倍数。The latch is to save the control signal sent by the host computer, and what is used in the present invention is the latch SN74HC573A. According to the size of the output signal of the amplifier, the upper computer sends out the control signal to switch the attenuator accordingly. The upper computer only needs to send out the control signal once, and the latch can latch it, keeping the attenuation multiple of the attenuator unchanged, unless the upper Confidentially switch the attenuation multiple.
本发明的放大器采用三级差分放大，单端输入，单端输出。采用差分放大的目的是为了减小共模干扰。放大器设计的关键就是要想方设法提高信噪比，如此方能检测到微弱的放电信号。The amplifier of the invention adopts three-stage differential amplification, single-end input and single-end output. The purpose of using differential amplification is to reduce common mode interference. The key to amplifier design is to try to improve the signal-to-noise ratio so that weak discharge signals can be detected.
因此放大器采用了低噪声的宽带运算放大器AD8001来实现，共有三级放大组成。为了减小放大器本身的噪声，三级放大器的放大倍数前级尽量大，后级尽量小，这样运放本身的噪声不至于被大量放大，降低放大器的本机噪声，提高检测放电信号的能力。此放大器的设计频带为20kHz～43MHz，最大增益为500倍。Therefore, the amplifier is realized by a low-noise broadband operational amplifier AD8001, which consists of three stages of amplification. In order to reduce the noise of the amplifier itself, the amplification factor of the three-stage amplifier should be as large as possible in the front stage and as small as possible in the rear stage, so that the noise of the operational amplifier itself will not be amplified by a large amount, reduce the local noise of the amplifier, and improve the ability to detect discharge signals. The design frequency band of this amplifier is 20kHz～43MHz, and the maximum gain is 500 times.
本发明的详细参数和设计参阅图6所示。Detailed parameters and design of the present invention are shown in FIG. 6 .
通过对本单元的性能测试，当输入大小为5mV的脉冲信号时，放大器在各个档位所测的脉冲响应如表1所示，可以看出该宽频带放大器满足设计要求。Through the performance test of this unit, when a pulse signal with a size of 5mV is input, the pulse response of the amplifier measured in each gear is shown in Table 1. It can be seen that the broadband amplifier meets the design requirements.
表1宽频带放大器的放大性能Table 1 Amplification performance of broadband amplifier
3.检测阻抗及宽频带放大器局部放电测试验证3. Detection impedance and wideband amplifier partial discharge test verification
1）实验室电晕放电模型测试1) Laboratory corona discharge model test
为了验证本发明的性能，通过实验室电晕放电模型测试，检测试验连线图请参阅图7。在该实验中选取的试品为电晕放电模型（针板）与4个2μF相串联的高压电容器（50kV无局放）并联。在进行测量之前，先采用方波校正单元对试品进行校正，其中方波信号施加在电晕模型的两端。校准完成后，对整个系统施加电压。通过振荡波电压源对试品逐步加压，当加压至4.5kV时，达到其局部放电起始电压（PDIV），开始放电。实验结果谱图如图8所示。从图中可以清晰看出采用此检测阻抗及宽频带放大器后测得的局部放电信号。随着电压的升高放电次数和幅值均会有所增加，且在90°附近有幅值较大的脉冲出现。In order to verify the performance of the present invention, through the laboratory corona discharge model test, please refer to Figure 7 for the connection diagram of the detection test. The sample selected in this experiment is a corona discharge model (needle plate) connected in parallel with four 2μF high-voltage capacitors (50kV without partial discharge) in series. Before the measurement, the sample is calibrated with a square wave calibration unit, in which a square wave signal is applied to both ends of the corona model. After calibration is complete, apply voltage to the entire system. The test sample is gradually pressurized by an oscillating wave voltage source. When the pressurization reaches 4.5kV, the partial discharge initiation voltage (PDIV) is reached and the discharge begins. The spectrum of the experimental results is shown in Figure 8. It can be clearly seen from the figure that the partial discharge signal measured after adopting the detection impedance and the broadband amplifier is used. With the increase of the voltage, the number of discharges and the amplitude will increase, and there will be a pulse with a larger amplitude near 90°.
本发明的实验室验证是在外施高电压条件下进行的，同时要求测量试品局部放电信号，因此，屏蔽室内不允许有任何非绝缘体靠近高压电极，以免对局部放电测量构成干扰。The laboratory verification of the present invention is carried out under the condition of externally applied high voltage, and the partial discharge signal of the test product is required to be measured at the same time. Therefore, any non-insulator is not allowed to be close to the high voltage electrode in the shielding room, so as not to interfere with the partial discharge measurement.
以上所述仅为本发明的一种实施方式，不是全部或唯一的实施方式，本领域普通技术人员通过阅读本发明说明书而对本发明技术方案采取的任何等效的变换，均为本发明的权利要求所涵盖。The above is only one embodiment of the present invention, not all or the only embodiment. Any equivalent transformation of the technical solution of the present invention adopted by those of ordinary skill in the art by reading the description of the present invention is the right of the present invention. covered by the requirements.
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