A method of detecting xlpe insulation degree based on partial discharge frequency characteristics
A technology of partial discharge and frequency characteristics, applied in the direction of testing dielectric strength, etc., can solve problems such as large errors, and achieve the effect of effective evaluation of XLPE insulation defect state
Active Publication Date: 2016-04-13
STATE GRID CORP OF CHINA +3
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Problems solved by technology
[0004] However, due to many factors that interfere with the measurement of partial discharge, there is a large error in the discharge measurement value compared with other high-voltage tests. Therefore, it is urgent and important to find a new method to judge the severity of XLPE insulation defects.
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[0030] The content of the method will be described below through specific experiments in conjunction with the accompanying drawings.
[0031] 1. Principle
[0032] According to engineering requirements, the defect can be simplified as figure 1 The equivalent model is shown, and the discharge at the defect is analyzed with this equivalent model. where C i is the equivalent capacitance of a single defect, C bi is the equivalent capacitance of the insulating medium of the part in series with the defect, C a with R a is the equivalent capacitance and equivalent resistance of the normal part of the insulation, Z is the external impedance, AC is the AC power supply, and the partial discharge amount of the defect severity detection is actually the sum of the partial discharge amounts of multiple defects. For a single equivalent capacitance C i As far as the conductance is small, it is negligible, and C i >>C bi . Since the duration of a pulse is generally ns level, for each ...
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The invention provides a method for detecting XLPE insulation degree based on partial discharge frequency properties. The method includes the first step of pre-processing an XLPE cable to be detected as the following ways, the second step of taking out the preprocessed XLPE cable to be detected, enabling a high-frequency CT station to detect discharge pulse signals of the XLPE cable to be detected, and enabling a synchronous coil to detect partial PD signals of the XLPE cable to be detected, the third step of building and using an expert diagnose system to separate and classify the collected signals and recognize the discharge modes, and building characteristic spectrograms representing different types of pulse properties, and the fourth step of judging the severity of XLPE insulation defects by observing the characteristic spectrograms of the pulse properties, and using obtained partial discharge measured data to come to a conclusion through comparison. The method has the advantages that discharge signal spectrograms can be obtained by carrying out partial discharge measurement on XLPE insulation of different defect severities, and the XLPE insulation defect state can be evaluated effectively.
Description
technical field [0001] The invention relates to a method for detecting the insulation degree of XLPE (cross-linked polyethylene), specifically a method for detecting the severity of XLPE insulation defects based on partial discharge frequency characteristics, which belongs to the technical field of power system measurement. Background technique [0002] Compared with ordinary polyethylene, cross-linked polyethylene (XLPE) has excellent electrical insulation properties, higher impact strength and tensile strength, outstanding wear resistance, excellent stress crack resistance, creep resistance and Dimensional stability, heat resistance, low temperature resistance, aging resistance, chemical resistance, and radiation resistance are also excellent. Therefore, XLPE is often used as an insulating material and is widely used in various voltage levels of power systems. It has high dielectric strength, small dielectric loss coefficient, good acid and alkali resistance, salt spray re...
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IPC IPC(8): G01R31/12
Inventor 杨帆陈俊武苏勇赵健康阮羚张耀东童歆夏荣
Owner STATE GRID CORP OF CHINA