High Head Hydro Powerplant Evaluation

Abstract

When the head on a hydroelectric powerplant is between about 250–700 m (800–2,300 ft) the turbine can be either an impulse or reaction Francis unit. For each type of unit the operating characteristics and design of the powerplant will be substantially different. This paper outlines a comparison of the two types of powerplant, which was undertaken for the 136 MW Cat Arm Development in Newfoundland, where a gross head of 386.5 m (1,268 ft) is harnessed. The initial cost‐benefit analysis indicated that a Francis unit should be selected, but a Pelton unit was chosen, based on an analysis of the operating characteristics and other unquantifiable benefits.