1 - Alaska Energy Data Inventory

4.06 PRESSURE AND SPEED REGULATIONA. General. The generator-turbine polar Moment of Inertia (WR2) isequal to 1,075,000 lb-ft 2 as established by HEDB. Synchronous speed ofthe generator-turbine is 600 r/min with maximum overspeed limited to a 50pct increase which is 900 r/min based on HEDB recommendations. In orderto calculate pressure and speed rise a computer program called "MSRWH" waswritten by Al aska District Personnel for the Harris Computer. "MSRWH"utilizes model data, which in this case was the Dworshak model and is basedon the arithmetic integration process as illustrated in reference 14.Pressure and speed rise values were based on results from "MSRWH" whichwere checked when possible by manual calculations.B. Wicket Gate Closing Rates. The valve closing pattern and theclosure times are the same as that used for the recommended plan.Equivalent closing time from full gate and 70 pct gate are 5.0 sand 3.5 s,respectively.The 5.0 s closure time results in maximum speed rise at anet head of 835 ft while the 3.5 s closure rate at maximum pool (maximumnet head), results in maximum pressure at the turbine. Figure 11 ofHydaulic Appendix B2 shows the gate closure rate.C. Pressure and Speed Rise. Pressure and speed rise were calculatedfor two conditions as follows:(1) Maximum penstock pressure is based on maximum load rejectionwhich is defined by blocked power output of 47,190 hp, maximum pool elevationof 1,022 ft, tail water elevation of 11.4 ft and minimum hydraul iclosses. Rejection Condition A on Plate B22 shows the location of the pOintwhich is defined by the above parameters.The maximum pressure gradient atthe turb'ine was 1,329.4 ft whi le the unit speed (at 3.5 s closure) wascalculated at 792 r/min • A 3.5 s valve closure was used because theinitial valve opening was equal to 70 pct as opposed to full gate as shownon Plate B22.These values were calculated by the above mentioned computerprogram "MSRWH," written by the Alaska District. Manual calculations usingthe Allievi Charts resulted in a maximum pressure gradient of 1,324.4 ftwith conditions as described above.B4-23