Oil-immersed type transformer solid insulation moisture content assessment method based on return voltage

Abstract

The invention discloses an oil-immersed type transformer solid insulation moisture content assessment method based on return voltage, comprising the following steps: 1) preparation work: the temperature of a transformer is lowered without forced oil circulation; an outgoing line terminal and a line of each winding sleeve are separated; and each phase of a high voltage winding and neutral points are in short circuit and grounded; 2) wire connection: each measured winding is in grounded insulation; 3) parameter configuration; 4) test end judgment: a polarized spectrum curve raises smoothly and then declines, when the peak value of the polarized spectrum curve appears, test is ended; when the tested polarized spectrum curve has serious jump or a plurality of peak values, the test is ended when the charging time Tc equals to 100s; 5) moisture content is judged according to a main time constant of the polarized spectrum curve; and 6) when the moisture content is less than 1%, the insulation state is good; when the moisture content ranges from 1% to 2.5%, the insulation state is general; and when the moisture content is higher than 2.5%, the insulation state is very poor. The invention can accurately assess brackish moisture content in insulation paper and judge the insulation and aging state of oil paper without suspended core and sampling and destroying the insulation material.

Description

technical field [0001] The invention belongs to the field of transformer insulation state diagnosis and life evaluation, and relates to a recovery voltage-based method for evaluating solid insulation of oil-immersed transformers. Background technique [0002] The operating reliability of transformers, especially large oil-immersed power transformers, is directly related to the safety and stability of the power system. According to statistics, the operating accidents of transformers are mainly caused by the failure of their insulation systems, so their life depends largely on the oil-paper insulation system. Aging state. During the operation of the transformer, the oil-paper insulation is subjected to various external stresses such as heat, electricity, machinery, and chemistry for a long time, which leads to a gradual decline in its own insulation and mechanical properties and may cause transformer failure. Therefore, accurately diagnosing the aging state of the oil-paper i...

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Problems solved by technology

[0007] Aiming at the technical problems of the evaluation method of water content of transformer solid insulation, the transformer needs to be treated by lifting the core to extract the insulation paper sample, the operation procedure is complicated and may damage the transformer insulation, and th

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