CAJ | 학술논문

换流变压器绝缘状态与交直流复合比例具有密切关系，研究放电特征与交直流复合比例之间的关系对换流变压器的故障诊断具有实际的工程意义。以内部气隙缺陷为研究对象，根据换流变压器内部的实际运行环境，搭建了一套交直流复合电压作用下油纸绝缘局部放电测量平台，采用常规脉冲电流法着重对比了不同交直流复合比例下油纸绝缘内部气隙起始阶段、临近击穿阶段及整个发展过程的局部放电特征。试验结果表明：每个比例交直流复合电压作用下绝缘内部气隙缺陷放电具有其特有的特征；交直流复合电压作用下油纸绝缘内部气隙放电所产生的空间电荷在电场作用下所形成的反向电场会使总起始电压Ui和总击穿电压Ut随着交直流复合电压中直流成分的增加而逐渐增大；起始阶段、击穿阶段及整个发展过程的放电脉冲重复率及放电量降低，而且随着直流所占比例的增加，负半周期放电重复率逐渐高于正半周期，放电相位逐渐向负半周期集中。该结论为实现换流变压器故障诊断及状态监测提供了一定的依据。
환류변압기절연상태여교직류복합비례구유밀절관계，연구방전특정여교직류복합비례지간적관계대환류변압기적고장진단구유실제적공정의의。이내부기극결함위연구대상，근거환류변압기내부적실제운행배경，탑건료일투교직류복합전압작용하유지절연국부방전측량평태，채용상규맥충전류법착중대비료불동교직류복합비례하유지절연내부기극기시계단、림근격천계단급정개발전과정적국부방전특정。시험결과표명：매개비례교직류복합전압작용하절연내부기극결함방전구유기특유적특정；교직류복합전압작용하유지절연내부기극방전소산생적공간전하재전장작용하소형성적반향전장회사총기시전압Ui화총격천전압Ut수착교직류복합전압중직류성분적증가이축점증대；기시계단、격천계단급정개발전과정적방전맥충중복솔급방전량강저，이차수착직류소점비례적증가，부반주기방전중복솔축점고우정반주기，방전상위축점향부반주기집중。해결론위실현환류변압기고장진단급상태감측제공료일정적의거。
Studying on the partial discharge of oil-paper insulation under different AC and DC combined proportions is important for the condition monitoring and fault diagnosis of converter transformer. Internal gas-gap defect was taken as the study object. Based on the condition of converter transformer, a set of platform for oil-paper insulation partial discharge measurement under AC and DC combined voltage was built. The characteristics of conventional pulse current signal of internal gas-gap defect partial discharge of the initial stage, close to breakdown stage and the entire development stages under different AC-DC combined voltages were compared. The results show that, the characteristics of internal gas-gap defect under each proportional AC and DC voltage are unique. With the decrease in the proportion of AC and DC combined voltage, the total initial voltage Ui and the total breakdown voltage Ut increase. However, due to the DC composition increased, makes the discharge pulse repetition rate and discharge capacity of the initial stage, the breakdown stage and the entire development stages have decreased to some extent. Meanwhile, with a higher percentage of DC, the discharge repetition rate of negative half cycle becomes gradually higher than the positive half cycle, and the discharge pulses concentrate in the negative half cycle of concentration.