Study on partial discharge characteristics of oil-immersed paper in wrinkled state under alternating current and direct current compound voltage

The insulation state of the converter transformer is closely related to the properties of the oil-paper insulation material. The study of the partial discharge characteristics of the wrinkled of the insulation paper has practical engineering significance for the fault diagnosis of the converter transformer. According to the actual operating environment inside the converter transformer, a set of oil-paper-insulated partial discharge measurement platform under the action of AC and DC composite voltage was built. The test results show that insulation paper wrinkles under the action of AC/DC composite voltage will cause insulation damage due to higher surface electric field and partial discharge; the discharge pulse repetition rate and discharge volume increase in the initial stage, development stage and final dangerous stage of discharge. The partial discharge caused by paper wrinkled significantly increases the CH4 content in the dissolved gas in the oil. This conclusion provides a certain basis for the realization of converter transformer fault diagnosis and condition monitoring.