Numerical Simulation of Hydraulic Transients in Hydropower Plant Using Safety Membranes

A new mechanical device consisting of a set of safety membranes has been used in several small hydropower stations in China in lieu of a surge tank. Safety membranes are controlled weak points mounted on the penstock near the powerhouse. Whenever pressure on the membranes rises to the preset value, one or more membranes rupture, protecting the penstock and the unit effectively. The device is simple, reliable, and beneficial. This paper proposes a mathematical model for analyzing hydraulic transients of a hydropower plant where a set of safety membranes is mounted to replace an expensive surge tank. The prevailing method is employed in order to solve the momentum and continuity equations describing transient flow in closed conduits. An optimization procedure is developed to guarantee the convergence of the interative process for calculating pressure rises due to water hammer when Kaplan turbines are installed. Using this model, transients of generator load rejections are calculated in Linzhengqu hydropower station (Hebei Province, China). Computed results agree well with those of field tests.