Prediction of hydraulic transient phenomena in Francis turbine

Hidravlični prehodni pojav je vsaka sprememba stacionarnega stanja v hidravličnem pretočnem sistemu. V hidroelektrarnah so vzrok hidravličnih prehodnih pojavov obratovalni manevri turbine. S simulacijskim programom SIMSEN smo simulirali trenutno razbremenitev in hitro zaustavitev Francisove turbine za dva primera hidroelektrarn. Rezultati so pokazali, da pride v pretočnem sistemu hidroelektrarne do vodnega udara. Vodni udar je hidravlični prehodni pojav, pri katerem pride do tlačnih pulzacij, ki lahko ogrozijo varnost celotnega sistema. V hidroelektrarnah vodni udar blažimo s podaljševanjem časa zapiranja vodilnika in z ventilom za vzporedni izpust vode. Rezultate programa SIMSEN smo primerjali z rezultati programa WCF. Rezultati obeh programov se dovolj dobro ujemajo, da lahko zaključimo, da je program SIMSEN primeren za napovedovanje hidravličnih prehodnih pojavov v hidroelektrarnah. A hydraulic transient phenomenon is every change of stationary state in a hydraulic flow system. The causes for hydraulic transient phenomena in hydroelectric power plants are operating manoeuvres of the turbine. Using the simulation software SIMSEN we simulated the load rejection and rapid shutdown of the Francis turbine in two cases of hydroelectric power plants. The results have shown that in the flow system of the hydroelectric power plant a water hammer occurs. The water hammer is a hydraulic transient phenomenon where pressure pulsations take place, which can endanger the safety of the whole system. In hydroelectric power plants the water hammer is alleviated by the prolongation of the guide vane closing time and with the pressure relief valve. We compared results of the software SIMSEN with the results of the software WCF. The results of both software match good enough, so it can be concluded that the software SIMSEN is suitable for predicting hydraulic transient phenomena in hydroelectric power plants