交直流复合电压叠加谐波电压下的绝缘纸电老化特性研究

Study on the Electrical Aging Characteristics of Insulating Paper under Harmonic Voltage Superimposed on AC-DC Compound Voltage

换流变压器是特高压直流输电系统中的关键设备,而绝缘纸是换流变压器中重要的绝缘与散热材料。由绝缘设计与缺陷导致的绝缘问题占据了换流变压器故障的绝大多数,因此研究换流变压器绝缘纸的电老化特性具有重要意义。根据换流变压器阀侧绕组绝缘承受的电压类型,采用典型的油浸绝缘纸作为模拟换流变压器纸绝缘的试验材料,开展了绝缘纸在交直流复合电压叠加谐波电压下的长时耐压试验,研究了绝缘纸的电老化特性。试验结果表明,谐波电压对绝缘纸的电老化特性影响显著,随着谐波含量的增加,绝缘纸的电老化失效时间减小,且5次谐波对绝缘纸电老化失效时间的影响比3次谐波的影响更大。

Converter transformers are the key equipment in ultra high voltage direct current transmission system.The insulating paper is an important insulating and heat dissipating material in converter transformers.Insulation problems caused by design and defects of insulation account for the majority of converter transformer faults,so it is of great significance to study the electrical aging characteristics of insulating paper of converter transformers.According to the voltage type that the insulation of the valve-side windings of the convertor transformer withstands,the typical oil-impregnated insulating paper was used as the test material to simulate the paper insulation of the converter transformers.The electrical aging characteristics of insulating paper under harmonic voltage superimposed on AC-DC compound voltage were studied.The experimental results showed that the harmonic voltage had significant influence on the electrical aging characteristics of the insulation paper.With the increase of the harmonic content,the electrical aging failure time of the insulation paper decreased,and the fifth harmonic had greater influence on the electrical aging failure time of the insulation paper than the third harmonic.