中文摘要：

电流互感器（TA）是电网控制回路的重要组成部分,失效时可能引起相对地故障或高能量爆炸,妨碍变电站的安全运行。为了提高电流互感器的运行可靠性,基于频域谱理论和测试技术,提出了联合频域介电谱和高压介损试验进行高压电流互感器绝缘状态及老化诊断的方法。首先利用频域介电谱（FDS）对3台220kV TA进行测试,得到了主绝缘的tanδ-f和C＊-f特性曲线。然后对设备进行了高压介损试验,得到了主绝缘的tanδ-U曲线,并将10kV工频介损与FDS测试结果进行了对比,验证了两者的一致性。从试验结果可知：绝缘严重老化或受潮均使得固体绝缘中水分含量增加、低频段的介质损耗升高;老化严重时,低频段的复电容实部随频率降低而增大,绝缘受潮时复电容实部基本不随频率变化;绝缘老化设备在tanδ-U曲线上呈现开口形状,绝缘受潮设备的tanδ基本不随电压U变化,为两者的区分提供了新途径。FDS作为一种估计纸中水分和油电导率的可靠工具,结合高压介质损耗试验有利于对高压TA绝缘进行更有效、准确的诊断。

英文摘要：

Current transformer（TA）is an important part of the power utility control circuits,and its failure may result in phase to ground fault or high energy explosion which seriously hinders the operation of substations.In order to improve the operation reliability of current transformers,the basic theory and testing technology of frequency dielectric spectroscopy are adopted to introduce a method used for insulation condition and aging diagnosis,which incorporates frequency domain spectroscopy（FDS）and high voltage dielectric loss test.Firstly FDS tests are performed on three 220kV oil-immersed TA.Tanδ-f and C＊-f waveforms are obtained for main insulation of each TA.Then high voltage dielectric loss tests are performed on the equipment to obtain tanδ-U waveform,which shows accordance to the FDS results at power frequency and 10kV.Furthermore,it is found that,both serious aging and damp result in increase of moisture content in solid insulation and the dielectric loss at low frequency level;the tanδ-U waveform of insulation affected by aging has a U-shape,and that of insulation affected only by moisture shows similar dielectric loss in the whole tested voltage range,which could be considered as a new approach to distinguish the two situations.It is concluded that,as an reliable tool to evaluate moisture content in papers and conductance of oil,FDS could offer more effective and accurate diagnosis to high voltage TA combining with high voltage dielectric loss tests.