In versions after 1.7.2 (excluding 1.7.2), the hydraulic generator has been removed and cannot be used. Only the hydraulic kinetic energy generator can be used in conjunction with the kinetic energy generator to generate electricity.
It can be used in previous versions. The use is to have water blocks around the hydroelectric generator (just like you). Energy production is very low. Adding water can consume water to produce electricity. Electricity production is increasing.