양수발전소의 수력학적 과도현상에 관한 연구(Ⅰ)

Abstract

This field test was conducted to investigate the hydraulic transient at a pumped storage power plant with four 250 MW pump turbines. The occurrence of a hydraulic transient may be a problem related to the water hammer that occurs during the pump start and pump input power shutoff or turbine start and turbine load rejection, which affects the hydraulic pressure change, flow-rate change, and rotational speed change of the pump turbine caused by the water hammer of the penstock and tailrace. The water hammer was field tested to investigate such hydraulic transients. Accordingly, the main factors in the field test must be determined to analyze the water hammer. We monitored the main sensors attached to the pump turbine and those attached to the inlet valve. The result after the field study confirmed that the occurrence of the water hammer during the pump start and pump stop under a normal operation of the pump turbines was not problematic. Moreover, during the load rejection test, an upsurge occurred in the penstock under the rapid closing of the upper and lower wicket gates, while a downsurge occurred in the draft tube and spread to both the upstream and the lower stream. As a result, the pressure rose in the penstock, and the pressure rapidly fell in the draft tube. Subsequent to the full close of the upper wicket gate, the water hammer repeatedly rose and fell in the tailrace between the pump storage power plant and the lower reservoir. Moreover, the pressure in the draft tube rose, and surging occurred in every 2 minutes.