Dynamic Closing Modelling of the Penstock Protection Valve for Pipe Burst Simulations

Abstract

The penstock protection valve equipped with downstream air valve is a safety component aiming to cut off the discharge in case of pipe burst. The hydraulic transient simulation of pipe burst scenario is challenging since the closing time results from the system dynamics, air is admitted through the downstream air valve and cavitation may occur in the penstock. To perform such simulation, a dynamic model of the penstock protection valve is developed and presented in this paper. Closing time, maximum flow rate reached during the pipe burst or maximum oil pressure in the cylinder of servomotor during the non-linear closing law are results derived with this model. Moreover, influence of cavitation in the valve and in the penstock are considered in the model. It is showed that simulation of pipe burst should consider i) cavitation model in the penstock protection valve, ii) water column separation in the penstock and iii) air admission by the air valves located downstream to the valve to obtain realistic results.