A study on key technology and demonstration application of UHV AC site assembled transformers

摘要

Many UHV AC power transmission projects have been put into commercial operation successfully in China. By the end of 2017, the backbone of UHV AC power grid has been built in the vast area of Sanhua (North, Central and East China). As a key equipment, more than 150 units of UHV AC transformers (single unit capacity of 1,000 MVA) had been put into operation successfully because of their excellent qualities in design, process, manufacturing, testing, transportation, installation, acceptance test and system commissioning etc., which ensures the stability and reliability of UHV AC power grid till now. However, due to the large size and heavy weight of UHV AC transformers, how to ensure safe and reliable transportation has always been a difficult problem needs to be noticed and addressed. Therefore, in order to meet the requirement of different transportation environment and transportation conditions, a site assembled transformer bank (in three-phase) have been put into operation as an demonstration application installed at the Jin-Zhong UHV AC substation of a UHV AC project from Shaanxi to Shandong in China. As a result, a series of technical problems have been successfully solved in split transportation and field assembly, and formed the general technical route of plant disintegration, split transportation, field assembly and final installation on concrete foundation. In this paper, achievements and experiences would be presented in key technology research, installation and acceptance test, system commissioning and trial operation of site assembled transformers. Feasibility and reliability of such kind of transformers would also be discussed deeply for UHV AC power transmission projects.