Abstract: The adding units of Wujiangdu Hydropower Plant were put in operation in 2004 in succession. It is first time found that the cracks were occurred in blades in overhaul period in 2007. The cracks were analyzed and treated, then the units were put in operation again, but the cracks were occurred frequently in some blades. In unit overhaul period in 2009, in the joint of trailing edge of blade and upper canopy of wheel blades of #1 hydraulic turbine, the angle steels were welded to enhance the strength. The dynamic balances of unit before and after the strength enhancing were compared and analyzed, and a basis for solving the problem of cracks in wheel blades was provided.

Key words: wheel of hydraulic turbine, crack of blade, strength enhancing