Analysis and treatment of power oscillations in hydropower plant Dubrava.

The paper introduces, describes and analyses the specific power oscillations in hydroelectric power plant Dubrava that can appear in large bulb turbines operating with low tailwater levels. The procedure for the identification of the cause of oscillations is described and it is experimentally shown that the cause of power oscillations is a disturbance on a specific runner blade. The physical background of the cavitation‐related phenomena that causes these oscillations is presented. Furthermore, it is shown that neither the automatic voltage regulator nor the transmission network disturbance is the source of oscillations, while the power system stabiliser can only partially damp them. Power oscillations reduce the average power output due to the operation in the unsteady output zone. These oscillations can cause damage to the equipment and reduce its lifespan. The effectiveness of various measures for treatment of these oscillations is discussed. A simple model for simulation of these oscillations is shown and verified against measurements. [ABSTRACT FROM AUTHOR]