±800kV换流变压器现场长时感应耐压带局部放电测量试验研究

Research on On-site Long Duration Induced AC Voltage and Partial Discharge Test of 800 kV Converter Transformers

鉴于±800kV换流变压器结构十分紧凑,绝缘结构比较复杂,绕组对地电容大,为适应世界第一个特高压直流输电工程——±800kV云广直流输电工程建设的需要,采用阀侧直接加压方式对±800kV换流变压器进行现场长时感应耐压带局部放电测量试验,不仅要求试验装置能提供很大的无功功率,还需试验变压器具有很高的输出电压,试验难度高。试验前,在试验频率的计算中增加了试验变压器试验无功功率的影响,并以此校核试验装置是否满足要求;试验以GB1094.3—2003《电力变压器第3部分绝缘水平、绝缘试验和外绝缘空气间隙》及DL417—1991《电力设备局部放电现场测量导则》确定加压程序和试验评价方法,直接从阀侧绕组加压。现场试验数据验证了该试验方法是正确的。该试验采用变频电源装置,具有试验设备少、接线简单等特点。

In view of the highly compact structure,complex insulation composition and large winding-to-earth capacitance of 800 kV converter transformers,and to meet the construction needs of the world＇s first UHVDC transmission project,the 800 kV Yunan-Guangdong DC power transmission project,the on-site long duration induced AC voltage（ACLD） and partial discharge test was made on 800 kV converter transformer when the applying voltage was loaded on the valve-side winding directly.This difficult test required the testing equipments of large reactive power and the testing transformer of very high voltage output.The influence of testing reactive power of testing transformer was considered in the test frequency computation before the test,thus checking whether the tester met the requirements or not.The voltage applying procedure and the test evaluation method were determined according to GB 1094.3-2003 Power transformers-Part 3： Insulation levels,dielectric tests and external clearances in air and DL 417-1991 Guide for partial discharge measuring of power equipment,the applying voltage loaded on the valve-side winding directly.The test method was verified by the field test data.Adopting variable-frequency power supply device,the test featured fewer test devices and simpler wiring,etc.