A cable partial discharge signal live detection device based on a closed power distribution switch cabinet

Abstract

The utility model relates to a cable partial discharge signal live detection device based on closed distribution switchgear, including ultrahigh frequency sensor, capacitive sensor, data acquisition and transmission module, data analysis module and monitoring interface display screen, ultrahigh frequency sensor, capacitive sensor connect data acquisition and transmission module, data acquisition and transmission module connect data analysis module, data analysis module connects the detection interface display screen, data acquisition and transmission module include preamplifier circuit and data transmission circuit, preamplifier circuit carries out modulation, amplification processing to the signal of sensor output, data transmission circuit will data transmission to data analysis module, monitoring interface display screen shows equipment state and real -time signal data, and this technical scheme is used to 10kV distribution network switchgear, ring main unit and so on equipment " do not open cabinet, do not power off " to the partial discharge signal detection and analysis of cable line.

Description

Technical Field

[0001] This utility model relates to the field of power equipment testing technology, and in particular to a cable partial discharge signal live detection device based on a closed power distribution switch cabinet. Background Technology

[0002] Partial discharge is a sign of insulation degradation in electrical equipment. Traditional detection methods include the pulse current method, ultrasonic method, and transient ground wave method. Among these, the pulse current method is a widely accepted method for testing the amount of partial discharge, calculating the discharge quantity by measuring the pulse current generated by the partial discharge. The ultrasonic method and the transient ground wave method determine the partial discharge condition by detecting the ultrasonic or ground wave signals generated by the discharge.

[0003] In existing technologies, conventional partial discharge detection devices typically use a snap-on high-frequency partial discharge current transformer (CT) connected to a grounding wire, and determine the partial discharge status by detecting high-frequency current pulse signals. In addition, some devices use conventional ultrasonic or transient ground voltage sensors for detection.

[0004] Disadvantages of existing technology 1. Conventional high-frequency partial discharge CT detection methods are susceptible to interference from ground plane clutter signals, leading to unstable measurement signals. When a large circulating current exists in the grounding wire, it can easily cause magnetic flux saturation in the CT, resulting in CT vibration, affecting measurement stability, and potentially posing safety hazards. High transmission impedance leads to significant signal attenuation, impacting detection accuracy.

[0005] 2. Conventional ultrasonic and transient ground voltage sensors: These have low sensitivity, making it difficult to detect weak partial discharge signals. They also have weak anti-interference capabilities, making them susceptible to interference in complex electromagnetic environments. Furthermore, they can only provide a single type of spectrum display (such as PRPD or PRPS spectra), unable to display multiple spectra simultaneously, and lack pulse clustering algorithm filtering capabilities, making it difficult to accurately distinguish between partial discharge signals and interference signals. Utility Model Content

[0006] In view of this, the purpose of this utility model is to provide a cable partial discharge signal live detection device based on a closed power distribution switch cabinet, which is used for the detection and analysis of partial discharge signals of cable lines in 10kV power distribution switch cabinets, ring network cabinets and other equipment without opening the cabinet or interrupting power.

[0007] To achieve the above objectives, this utility model adopts the following technical solution: a cable partial discharge signal live detection device based on a closed power distribution switchgear, comprising an ultra-high frequency sensor, a capacitive sensor, a data acquisition and transmission module, a data analysis module, and a monitoring interface display screen; the ultra-high frequency sensor and the capacitive sensor are connected to the data acquisition and transmission module, the data acquisition and transmission module is connected to the data analysis module, and the data analysis module is connected to the detection interface display screen; the ultra-high frequency sensor includes an antenna, a balun, a pre-processing circuit, and a shielding base; the antenna receives the target signal, the balun performs impedance matching, the pre-processing circuit amplifies and modulates the high-frequency signal, and the shielding base isolates external ultra-high frequency signals; the capacitive sensor couples the high-frequency current pulse signal generated by partial discharge in the device under test into the measurement circuit; the data acquisition and transmission module includes a pre-processing circuit and a data transmission circuit; the pre-processing circuit modulates and amplifies the signal output by the sensor; the data transmission circuit transmits the data to the data analysis module; the monitoring interface display screen displays the device status and real-time signal data.

[0008] In a preferred embodiment, two high-frequency partial discharge synchronous acquisition channels are included to synchronously test the live indicators of adjacent bay switchgear.

[0009] In a preferred embodiment, it includes one high-frequency partial discharge synchronous acquisition channel and one ultra-high frequency partial discharge acquisition channel to synchronously acquire the high-frequency signal and ultra-high frequency signal of the interval.

[0010] Compared with the prior art, the present invention has the following beneficial effects: The present invention is used for the detection and analysis of partial discharge signals of cable lines in 10kV distribution network switchgear, ring main unit and other equipment without opening the cabinet or interrupting power. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a preferred embodiment of the present invention. Detailed Implementation

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0013] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0014] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0015] A live-line detection device for cable partial discharge signals based on a closed power distribution switchgear, reference Figure 1 The system includes an ultra-high frequency (UHF) sensor, a capacitive sensor, a data acquisition and transmission module, a data analysis module, and a monitoring interface display screen. The UHF sensor and capacitive sensor are connected to the data acquisition and transmission module, which in turn is connected to the data analysis module. The data analysis module is also connected to the monitoring interface display screen. The UHF sensor includes an antenna, a balun, a pre-processing circuit, and a shielding base. The antenna receives the target signal, the balun performs impedance matching, the pre-processing circuit amplifies and modulates the high-frequency signal, and the shielding base isolates external UHF signals. The capacitive sensor couples the high-frequency current pulse signal generated by partial discharge in the device under test into the measurement circuit. The data acquisition and transmission module includes a pre-processing circuit and a data transmission circuit. The pre-processing circuit modulates and amplifies the signal output by the sensor. The data transmission circuit transmits the data to the data analysis module. The monitoring interface display screen displays the device status and real-time signal data.

[0016] This device combines pulsed current method and ultra-high frequency (UHF) detection technology, acquiring partial discharge (PD) signals through UHF and capacitive sensors. Advanced digital signal processing algorithms are then used to analyze and process the signals, enabling high-precision detection, localization, and analysis of PD. The device features multi-channel input and real-time acquisition capabilities, simultaneously processing PD signals from both pulsed and UHF sensors, and visually displaying various PD spectra and signal characteristics on a control panel.

[0017] Specifically, it includes: Ultra-high frequency (UHF) sensor: Employing an Archimedes spiral antenna and related pre-processing circuitry, it possesses comb-like response capability, achieving an optimal balance between broad spectrum and high gain. It exhibits higher sensitivity and equivalent height, and demonstrates superior RF signal sensing capability in the 300MHz to 3GHz frequency band. The UHF sensor primarily consists of an antenna, a balun, a pre-processing circuit, and a shielded base. The antenna receives the target signal, the balun provides impedance matching to reduce signal attenuation, the pre-processing circuit amplifies and modulates the high-frequency signal, and the shielded base effectively isolates external UHF signals.

[0018] Capacitive sensors: Utilizing the busbar support capacitor within the switchgear, similar to the coupling capacitor in the pulse current method, they can directly couple partial discharge signals from high-voltage circuits, offering superior performance compared to other conventional live-line detection methods. This sensor couples the high-frequency current pulse signal generated by partial discharge in the tested equipment into the measurement circuit via a capacitive sensor within the live-line indicator circuit.

[0019] Data acquisition and transmission module: The acquired signals are converted into digital signals through analog-to-digital conversion and other methods. The preamplifier circuit modulates and amplifies the weak signals output by the sensor. The preamplifier circuit can be fully or partially embedded in the front-end sensor or the back-end detection host; when set up independently, it functions as a preamplifier.

[0020] The data transmission module offers multiple communication options, including USB, fiber optic, RJ45, WIFI, and 3G. Except for USB, all other communication modes follow the TCP / IP protocol and conform to the mainstream communication mode of IEC61850, ensuring that data can be transmitted to the data analysis module in real time.

[0021] Data Analysis Module: The acquired digital signals undergo filtering and noise reduction. The detection host receives the signals acquired by the detection unit, processes them through signal filtering and level adjustment, and then digitizes them using a high-speed AD converter. The digitized electrical signals are then processed by a high-speed FPGA programmable gate array circuit using time-domain, frequency-domain, and spectrum algorithms. Finally, the ARM system enables human-machine interaction and data storage.

[0022] A specific time-frequency clustering algorithm is used to process the detected pulses and classify and identify pulses from different sources based on equivalent wavelength and characteristic frequency. This facilitates the formation of different pulse clusters and effectively separates noise and partial discharge signals, as well as different types of partial discharge signals.

[0023] User interface module: It provides an intuitive monitoring interface that displays device status and real-time signal data. The display panel mainly shows the partial discharge PRPD and PRPS spectra, as well as the peak and transient values ​​of partial discharge over multiple cycles. It also features intelligent background removal and phase shift functions, and can automatically display the characteristic spectrum of the real partial discharge signal after filtering by the pulse clustering algorithm.

[0024] Users can select different functions using the buttons on the panel to enter the corresponding function pages, such as measurement mode switching, parameter settings, data storage, and historical data viewing.

[0025] When a partial discharge signal is detected, the signal source is determined and bitwise operations are performed using the following steps: 1. Use two high-frequency partial discharge synchronous acquisition channels to synchronously test the live indicators of adjacent switchgear. By comparing the signal arrival time, determine which switchgear the partial discharge comes from.

[0026] 2. Simultaneously acquire the high-frequency signal and the ultra-high-frequency signal of this interval through one high-frequency partial discharge (PD) acquisition channel and one ultra-high-frequency PD acquisition channel. If the PD signal occurs simultaneously with the ultra-high-frequency signal, the PD signal is a PD signal inside the switch cabinet; otherwise, it is a cable PD signal.

[0027] 3. Based on the original pulse waveform acquired from the charged indicator in the high-frequency partial discharge channel, the partial discharge is located using the pulse reflection localization method (TDR).

[0028] To address the issue of high-frequency partial discharge (PD) detection being susceptible to high-frequency pulse interference from the grounding grid, a method combining "full waveform preservation" and "digital signal processing" is employed. By preserving the original waveforms of continuous high-frequency signals over a period of time, signal processing algorithms such as wavelet transform are used to extract pulse waveforms from the original waveforms, enabling the detection of small signals from large signals. For several detected high-frequency pulse waveforms, an automatic clustering algorithm is used to automatically group waveforms with similar shapes, and the PRPD (partial discharge pulse) spectrum of each group is examined to determine whether it is a PD or interference signal. Signals identified as PD are further analyzed using the PRPD spectrum to confirm their discharge type and locate the defect.

[0029] The ultra-high frequency sensor used in this invention employs an Archimedes spiral antenna and related pre-processing circuitry, exhibiting higher sensitivity and equivalent height. It possesses better radio frequency signal sensing capability in the 300MHz to 3GHz frequency band, enabling more accurate detection of weak partial discharge signals. Compared to conventional partial discharge instruments with an ultra-high frequency detection band of 300MHz to 1.5GHz and an average effective height generally within 10mm, this invention has an ultra-high frequency detection band of 300MHz to 3.0GHz and an average effective height of over 20.5mm, effectively improving the detection sensitivity of partial discharge signals.

[0030] This invention features a device with multi-channel input and real-time acquisition, capable of simultaneously processing partial discharge signals from pulse sensors and ultra-high frequency sensors. Compared to the single-sensor detection method in the prior art, this invention can acquire multiple types of partial discharge signals simultaneously, thus improving detection efficiency.

Claims

1. A cable partial discharge signal live detection device based on a closed distribution switchgear, characterized in that, The system includes an ultra-high frequency (UHF) sensor, a capacitive sensor, a data acquisition and transmission module, a data analysis module, and a monitoring interface display screen. The UHF sensor and capacitive sensor are connected to the data acquisition and transmission module, which in turn is connected to the data analysis module. The data analysis module is connected to the monitoring interface display screen. The UHF sensor includes an antenna, a balun, a pre-processing circuit, and a shielding base. The antenna receives the target signal, the balun performs impedance matching, the pre-processing circuit amplifies and modulates the high-frequency signal, and the shielding base isolates external UHF signals. The capacitive sensor couples the high-frequency current pulse signal generated by partial discharge in the device under test into the measurement circuit. The data acquisition and transmission module includes a pre-processing circuit and a data transmission circuit. The pre-processing circuit modulates and amplifies the signal output by the sensor. The data transmission circuit transmits the data to the data analysis module. The monitoring interface display screen displays the device status and real-time signal data.

2. The cable partial discharge signal live detection device based on the closed power distribution switchgear according to claim 1, characterized in that, It includes two high-frequency partial discharge synchronous acquisition channels to synchronously test the live indicators of adjacent switchgear bays.

3. The cable partial discharge signal live detection device based on a closed power distribution switchgear according to claim 1, characterized in that, It includes one high-frequency partial discharge synchronous acquisition channel and one ultra-high frequency partial discharge acquisition channel, which simultaneously acquire the high-frequency signal and the ultra-high frequency signal.

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