The world’s longest sea bridge, Hong Kong–Zhuhai–Macau Bridge, has the largest scale of highway electromechanical installation and in which the most complex technologies and most difficult constructions are applied. In the mega project, about 200 sets of Kehua UPS system was installed in the substations of the east and west artificial island and the port artificial, working in the harsh environment of high temperature, high humidity and corrosion, which poses a comprehensive challenge to the Kehua’s product quality. With excellent reliability and high efficiency, Kehua’s AC/DC power system provides: comprehensive battery management function which automatically monitor the terminal voltage, charge and discharge current of the battery; battery temperature compensation which greatly extend the battery life; communication function which flexibly communicate with the computer monitoring system.