The excitation system of Xiaoxiang hydropower station was designed by Guangzhou electric apparatus academy of scientific research in 1995.It′s an early type of TKL11-6.As its putting into running with unit 1 of Xiaoxiang

it displayed bad modulation capability and stability step by step.In recent years the capacity and voltage of power grid is improving continuously.That radically requires the modulation characteristic of each terminal generator of the power grid more highly.In order to adapt the trend of the electric power system and improve the benefit of enterprise.Xiaoxiang hydropower station made its excitation system of two units a complete alteration

and gain a good effect.In this text it thoroughly discusses and compares the problems and the techno-alteration.It can offer a nice reference for other minitype power stations who want to upgrade their excitation system.