水电站尾水调压室断面面积敏感性分析研究

Sensitivity analysis of section area of tailrace surge chamber in hydropower station

基于瞬变流理论,采用弹性水锤特征线法,建立合理的边界条件,对有较长尾水隧洞的水电站调压室断面面积变化敏感性进行数值模拟分析,重点研究尾水调压室的断面面积对大波动工况下的调压室水位波动、机组最大转速升高率、蜗壳末端压力变化和水力干扰工况下对水电站机组出力摆动的影响。对同一特征工况,在大波动下,调压室断面直径为28 m,即断面面积为615.752 m2时,调压室最低涌浪水位达到2 218.97 m,蜗壳末端最大压力达到269.17 m(压力升高24.48%),机组转速最大上升率达到42.19%,满足调节保证计算要求。水力干扰工况下,并入同一电网时,随着调压室断面面积增加,机组出力摆动减小,对于大电网而言,出力摆动相对差值变化较小,两台机组甩负荷时,受扰机组出力摆动相对差值相差0.08%,一台机组甩负荷时,受扰机组出力摆动相对差值相差0.03%。综合考虑计算结果及调压室的工程经济性,推荐本电站调压室断面面积取615.752 m^2。

Based on the theory of transient flow,the elastic water hammer characteristic line method was used to establish the reasonable boundary conditions,and the numerical simulation analysis was made on the sensitivity of section change of surge chamber in long tailrace tunnel. and detailed study the effect of surge of water level in surge chamber maximum rise rate of disturbed unit and pressure at end of volute under large fluctuation condition and unit output swing of hydropower station on the section area of Tailrace surge chamber under hydraulic interference condition. On the same characteristics condition,under the condition of large fluctuations,when the surge chamber area is 615. 752 m^2,minimum surge level water level reached 2218. 97 m,the end of the volute pressure reaches 269. 17 m（ pressure on 24. 48%）,maximum speed rise rate reached 42. 19%,which meet the request of the regulation guarantee calculation. Under hydraulic disturbance condition,incorporated into the same grid,when the surge chamber section area increased,the unit output swing will decrease. For large power grid,the relative difference of output swing have smaller minor change to small power grid. Besides,the relative difference of disturbed unit differ is 0. 08% when double units load rejection,and the relative difference of disturbed unit differ is 0. 03% when just single unit load rejection. Considering the calculation result and the engineering economy of the surge chamber synthetically,it is reasonable to recommend that the sectional area of the tailrace surge chamber of the power plant be 615. 752 m^2.