On April 14, 2011, Hubei Electric Power Research Institute adopted UHV frequency conversion resonance test equipment produced by Suzhou Huadian (complete equipment including: 300kW frequency conversion power supply, 300kVA excitation transformer, 250kV/6A×4 high-voltage resonance reactors, 1000kV AC partial voltage The 1000kV GIS AC withstand voltage test was successfully carried out at the 1000kV UHV Jingmen Station of the State Grid.