Improved return voltage measurement mode oil-paper insulation state assessment method

Abstract

The invention provides an improved return voltage measurement mode oil-paper insulation state assessment method. The method is the improved return voltage measurement method which performs one time oflong-time charging and multiple times of short-time continuous discharging. The experiment of the samples of different degrees of dampness is performed through automatic acquisition of the electrometer programming for acquiring the return voltage data, and the parameter of each branch of the extended debye equivalent circuit is identified according to the initial slope measured by each time of discharge process; and finally the return voltage and the initial slope of each discharge link are calculated through combination of network function analysis. The analysis indicates that the initial slope calculation value and the measurement value curve have high overlap ratio so that the parameter of the equivalent circuit identified by the initial slope acquired by the improved return voltage measurement method is effective; meanwhile, multiple times of cycle charge and discharge processes of the conventional return voltage are simulated on the equivalent circuit by using matlab. The experiment time is shortened to be less than one third of that of the conventional method, and the reduced return voltage polarization spectrum can also assess the insulation state of the transformer oil-paper insulation sample.

Description

technical field [0001] The invention relates to the technical field of transformer oil-paper insulation aging and life prediction, in particular to an oil-paper insulation state evaluation method based on an improved recovery voltage measurement method. Background technique [0002] Oil-immersed power transformers have the advantages of high dielectric strength and long service life, so they are widely used in power systems. However, during the operation of transformers, they will inevitably be subjected to electrical, thermal, mechanical stress and other environmental factors. Therefore, it is of great theoretical and practical significance to study the diagnosis method of the transformer oil-paper insulation state and correctly evaluate the insulation state of the transformer to ensure the safe, stable and reliable operation of the entire power grid. [0003] At present, the diagnostic methods for the transformer oil-paper insulation state are all non-destructive diagnosti...

AI Technical Summary

Problems solved by technology

However, the long measurement time of the traditional recovery voltage method is a major defect. It takes a lot of time to repeat charging and discharging many times. In each cycle, the peak value of the recovery voltage needs to be measured, which further prolongs the measurement time. 3 to 5 hours, the efficiency is low; most of the existing improvement methods are based on charging once and discharging once, and repeated measurement of multiple cycles, just to study the influence on the characteristic quantity by changing the charging and discharging time In addition, the traditional recovery voltage measurement method directly evaluates the insulation state of transformer oil paper with the measured characteristic quantity, and the experimental error has a great influence on the result, while the main The time constant is the most commonly used insulation diagnosis characteristic quantity in the recovery voltage measurement method. The determination of the main time constant directly affects the final diagnosis result. Therefore, it is necessary to determine the time corresponding to the peak value in the polarization spectrum as accurately as possible.

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