特高压变压器调压方式的探讨

Inquire into Voltage Regulating Method for UHV Transformer

针对特高压变压器的型式等问题进行了探讨分析。特高压变压器在考虑体积、造价及可靠性的情况下,采用单相自耦变压器成为必然。对于特高压中采用的自耦变压器来说,其调压方式有自身特殊的地方。在一般的双绕组变压器中,有载调压装置往往连接在接地的中性点上,这样调压装置的电压等级可比在线端调压时低。而自耦变压器中性点调压则会带来相关调压问题。故自耦变压器调压时,常采用线端调压方式。1000kV自耦变压器因其电压等级的原因,中压线端调压方式很难实现。在对中压线端调压和中性点调压方式,有载和无励磁两种调压方式进行分析比较的基础上,对特高压自耦变压器采用中性点无励磁调压方式的合理性进行了分析;考虑到特高压变压器在系统中的重要性和可靠性,对单独设置调压变压器的必要性进行探讨;对补偿原理进行了说明。

With the construction of the ultra high voltage （UHV） ac project, the domestic power grids will have a rush development. As the key equipment, UHV transformer should be researched thoroughly. It is necessary to adopt single-phase autotransformers in AC UHV system when taken account of volume, cost and reliability etc. For UHV autotransformer, its voltage regulating method is special because of its voltage is so high. For an ordinary transformer, on-load tap-changer is generally connected to neutral point which is grounded. This is because the voltage grade of the voltage regulating device can be lower than regulating from line terminal. But there is a problem of related voltage change for an autotransformer. So 500 kV autotransformers generally adopt regulating from intermediate line terminal. Voltage grade on the intermediate voltage line terminal of 1000 kV autotransformer is so high that regulating from intermediate voltage line terminal is not available. In addition, which regulating type is used, on-load regulation or off-circuit regulation, should be thought in according to system and equipment＇s inherent characteristics. Based on analysis and comparison of the regulating position and regulating type, this paper discusses the rationality of off-circuit regulating from neutral terminal on UHV autotransformers. For the sake of importance and reliability, this paper discusses the necessity of separate voltage regulator and introduces the principle of compensation transformer.