Due to the high field strength in high-voltage electrical equipment, when there are some defects in the equipment, partial discharge will occur in operation. Through the detection and analysis of partial discharge signal, we can judge whether there is some insulation hidden danger in electrical equipment.

Partial discharge produces a series of physical phenomena and chemical changes such as light, sound, electrical and mechanical vibration in and around the electric equipment. These physical and chemical changes along with partial discharge provide detection signals for monitoring the internal insulation status of electrical equipment. According to the different detection principles and methods, the commonly used PD detection methods include UHF method, ultrasonic method and high frequency current coupling method.

PD live detection system in substation is a special PD detection tool for PD experts in power industry, which is used to detect insulation defects of substation equipment. Based on the joint detection method of acoustic and electric, the system uses a high-speed digital storage oscilloscope to record and analyze the partial discharge signal of the equipment, which greatly retains the characteristic information of the partial discharge signal. The system can compare and analyze the information of different frequency bands of UHF, AE and HFC signals, so as to effectively distinguish the real partial discharge signal and external interference signal. Based on UHF detection, the system supports all kinds of built-in and external UHF Sensors of substation equipment. It can carry out partial discharge test and diagnosis analysis for the equipment to be tested in operation state, and accurately locate and determine the defect type and evaluate the hazard degree of the defect according to the signal propagation delay and strength, so as to understand and master the operation state of the equipment and avoid major accidents Happen.

Product configuration

According to different detection requirements, the PD positioning system can be configured with corresponding components, including: high-speed digital oscilloscope, UHF sensor, contact ultrasonic (AE) sensor, non-contact ultrasonic (AE) sensor, high-frequency current sensor (HFCT), UHF and ultrasonic signal conditioning unit, UHF filter, etc.

Main functions and features

the comprehensive application of UHF, ultrasonic and high frequency current detection technology can effectively solve the problem of anti-interference in the local discharge test of the substation, and improve the reliability of the detection results;

Using high-speed digital storage oscilloscope, the waveform details and time-domain characteristics of UHF, ultrasonic and high-frequency current signals can be analyzed;

the test is mainly based on UHF patrol. When problems are found and combined with ultrasonic and high frequency current detection, the local discharge charging test is fast and efficient;

by using the combined acoustic and electrical detection technology, the local discharge source can be accurately located and analyzed, with high positioning accuracy;

the type of PD can be determined according to the phase and waveform characteristics of PD signal;

the system can be used for local discharge and live detection of substation GIS, switchgear, transformer, power cable and other equipment.

Technical index

Power supply system：85-264VAC / 50Hz, built-in battery

System sampling rate：JD-S100：4GHz

Analog bandwidth：1 —— 2GHz

Measurement channel：4-channel (synchronous sampling)

Sensor band

UHF sensor: 300MHz —— 1500mhz

Ultrasonic sensor: 20kHz —— 300kHz

High frequency current sensor: 500khz-30mhz

Local radio patrol and location

According to the structural characteristics of the power equipment operating in the substation, the UHF, HFCT and ultrasonic joint test method (combined acoustic and electric method) is used to detect the partial discharge and electrification of the power equipment. The UHF information, high frequency current information and ultrasonic information of PD signals are extracted simultaneously by the combined acoustic and electric method. Through the comparative analysis of the three signals, the field interference can be eliminated more effectively, and the accuracy of PD positioning and defect type identification can be improved.

The partial discharge detection method based on the combination of sound and electricity is shown in the attached figure. Taking GIS equipment as an example, the external UHF sensor is placed near the insulator, the ultrasonic sensor is placed on the GIS shell, and the HFCT is installed on the ground wire of GIS cable terminal. The PD signals detected by each sensor are transmitted to the PD detection system or high-speed oscilloscope positioning system for processing, so as to realize PD positioning analysis, pattern recognition and insulation level diagnosis. SHAPE  * MERGEFORMAT

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