There are many better power transformer manufacturers in China, and different manufacturers focus on different voltage levels. For example, ABB in Hefei, Siemens in Jinan, transformers in Liyang, Jiangsu, and a joint venture in Guangzhou all produce 1 10Kv transformers.
As for 10kv transformer, there are many manufacturers, such as Shanghai Delo. You can learn more from the local power supply department.
Gao Ping transformer is unclear, and their high-voltage switches have a long production history.