1 - Alaska Energy Data Inventory

G. Load Demand Surge and Selection of Bottom Elevation.Condition 0 on Plate 818 represents full load demand. Thiscondition determines the lowest water surface elevation that will occur inthe surge tank. The parameters are minimum power pool elevation of 825 ft,wicket gates opened to full gate, tailwater elevation of 12.5 ft andmaximum hydraulic losses through the power conduit. A zero flow conditionis assumed at zero time with the wi cket gates fu lly opened ina governortime of 5 s. The initial water surface elevation in the surge tank was 825ft which corresponds to minimum power pool; Calame - Gaden, R.D. Johnson,IIMSURGE II and IIWHAMO II resulted in minimum water surface elevations of 772.0,770.6, 774.6 and 771.4 respectively. The result of IIWHAMO II at elevation771.4 is to be used for minimum surge elevation. On this basis the topelevation of the surge tank drift tunnel was selected at elevation766.4 ft. This will provide a 5 ft seal under the worst condition.Pl ate B20 shows the surge tank load demand prof il es produced by programsIIWHAMO II and IIMSURGE".H. Load Acceptance Characteristics.Plate 820 also includes a curve which illustrates the turbineoutput in hp for condition D. This curve shows the rapid load pickupcapability of the turbine with the vented surge tank. Assumptions used forload demand, condition 0, are conservative in nature in that no initialflow was assumed through the turbine at the beginning of the demand cycle.In most cases the turbine would be operated at speed-no-load before loadingto full gate which would result in a downsurge not quite as severe as theone computed. A remote possibility exists that the turbine could be thrownon full load when operating as a synchronous motor with tailwater aepresseawith compressed air. In such a case no flow would exist through theturbine prior to load demand, and the demand profile shown on Plate 820could apply. Good correlation between IIWHAMO II and IIMSURGE II can be seen onPlate 820.B3-12