±1100kV直流分压器外绝缘结构的设计

Investigate on the External Insulation Design for ±1100 kV DC Voltage Divider

在±1 100 k V特高压直流输电设备外绝缘设计尚属空白的情况下,笔者通过对±1 100 k V直流分压器空心绝缘子爬电距离、干弧距离的计算,对伞裙结构及其参数的设计以及均压环配置的研究,探讨了±1 100 k V特高压直流输变电设备外绝缘设计方法与步骤,为特高压直流输电设备外绝缘设计提供理论参考。以交流外绝缘设计为基础,通过分析交、直流复合绝缘子爬电距离的关系,完成±1 100 k V直流分压器绝缘子爬电距离的计算。分析了影响直流换流站输电设备绝缘水平的因素,确定了直流绝缘子干弧距离是由正极性操作冲击电压决定原则,并对±1 100 k V直流正极性操作冲击电压特性进行了分析与计算,进而完成干弧距离的估算。在上述工作的基础上,依据IEC 60815标准对伞裙结构及其特征参数进行了设计与校验。最后,建立直流外绝缘电场计算模型,完成均压环的配置,并采用遗传算法对均压环的结构参数进行优化设计。

In this paper the method and procedures of external insulation design for ± 100 kV DC voltage divider are discussed on the condition that there is neither design standard nor experience before. The insulation design of ± 100 kV DC voltage divider includes calculation of creepage distance and dry arc distance, configuration of shed and grading ring, which can provide suggestions for ± 100 kV DC transmission system insulation design. Based on the insulation design of AC transmission system, the ±100 kV DC voltage divider insulation design is completed in this paper. The relationship of composite insulator creepage distance between AC transmission system and DC transmission system is clearly understood through analyzing the difference of DC insulator and AC insulator, and then creepage distance is easily obtained. Factors influencing the insulation level of DC converter substation are analyzed, and a conclusion can be drawn that the dry arc distance is determined by the positive polarity switching impulse voltage. Upon that the characteristic of switching impulse voltage under ± 100 kV DC operation voltage is analyzed and the waveform and amplitude of switching impulse voltage in ±100 kV DC system is acquired. Based on these, the dry arc distance is calculated. According to the obtained creepage distance and dry arc distance, the specific size of sheds, such as the shed＇s length, umbrella spacing and umbrella dip are received on the basis of standard IEC 60815. In the end, an electric filed calculation model is established, toconfigure the grading ring, and to optimize its parameters by adopting the genetic algorithm.