September 9-14, 2014, at the ±800kV DC UHV converter station in Pu'er, Yunnan, Suzhou Huadian 1000kV non-partial discharge variable frequency series resonance test system successfully carried out the external AC withstand voltage and partial discharge test of the converter transformer.

The 5500kW high-voltage variable frequency power supply test system successfully carried out on-site no-load and load tests of the converter transformer, creating two world records. The 2400kV UHV DC without partial discharge test device successfully carried out the DC withstand voltage and partial discharge test of the converter transformer.