【作者】 赵冲；

【导师】 李忠华；

【作者基本信息】 哈尔滨理工大学 ， 高电压与绝缘技术， 2011， 硕士

【摘要】 变压器是电力系统中最核心的电气设备,油纸绝缘是电力变压器的主要绝缘形式。变压器安全运行直接关系到电网的安全与稳定。一直以来,国内外学者关注的是高温下油纸绝缘特性,高温下的老化决定了变压器可靠性和运行寿命。但是近几年我国东北地区出现了低负荷变压器或备用变压器在异常低温条件下发生绝缘故障的现象。为此,进行低温环境下油纸绝缘特性的研究以保证严寒地区变压器的安全运行具有较大的经济效益和社会效益。为了实验研究油纸绝缘的低温电气绝缘性能,首先研发了具有隔热性能的高压穿墙套管,并将其安装固定在低温冰箱的上盖上,从而构建可以模拟现实中变压器低温环境运行的实验平台。本文重点研究了低温条件下不同油纸比例的油纸绝缘的交流介电性能与介电强度,以及微水含量对其影响规律等。实验结果发现:在降温过程中,油纸绝缘系统的损耗因数表现出先降后升的变化趋势,并且微水含量越高,损耗因数就越大;而相对介电常数降温过程表现为单调上升;交流击穿电压则变化规律表现出两次下降过程,这可能与降温过程中微水从油中析出和纸中挤出两个过程相关。根据实验结果可推断,极低温度下变压器绝缘故障与微水含量密切相关,欲保障油纸绝缘变压器极低温度下的安全运行绝缘中微水含量必须严格限制。更多还原

【Abstract】 Power transformer is the most important equipment in power system,and the oil-paper insulation is used in big power transformers.The safety of the oil-paper insulating transformers is related to the security and stability of power grid directly.The high temperature properties of oil-paper insulation were forcused by a lot of scholars in world,due to the high temperature aging determined transformer reliability and operational life.Recently,the insulation failure occurred in low-load transformer or standby transformer under extremely low temperature in the northeast of China.So,studying the low-temperature properties of oil-paper insulation to ensure the safe operation of transformer in extremely cold area has great economic and social benefits.In order to study the insulation property of oil-paper under low temperature, the thermal insulated bushings was developed with the helped by cable insulation technology at first.And then fix it on the cover of low temperature fridge.So as to construct an experimental platform, which can simulate reality low temperature condition.This article focuses on the AC dielectic properties and dielectic strength with different rates of oil-papers in oil-paper insulation.The experiment shows that the loss factor of oil-paper insulation system decreases first,then rises and show the trend.And the higher moisture of oil-paper insulation is the larger the loss factor will be. However, the relative dielectic constant monotonously rises as the temperature decreases.The AC breakdown voltage declines two times.It maybe relates to the precipitation of water from oil and the extrusion from paper. According to the expriment results, it can be inferred that transformer insulation fault is closely related to moisture content in extremely low temperature.In order to make sure the safe operation of oil-paper insulation transformer in extremely low temperature,the moisture content in insulation must be strictly limited.更多还原