基于正交设计的灯泡贯流式机组关闭规律优化

Optimal design of close law for bulb tubular type turbine based on orthogonal design

建立以转速升高、导叶前水压力以及轴向水推力组成的过渡过程目标函数,选取了相应的权重系数.采用适于多因素、多水平的正交设计计算法进行机组关闭规律寻优.给定导叶第一段关闭时间,以第二段关闭时间、分段点开度和桨叶关闭时间为因子,每个因子取4水平进行正交设计计算.研究表明:最佳导叶、桨叶关闭规律下,转速升高、导叶前水压力、轴向水推力以及尾水管进口压力等过渡过程品质较优化前有明显的改善.桨叶缓慢关闭能减小引水管中水击压力以及尾水管进口的真空度,可显著降低机组转速升高及轴向反推力.通过正交设计计算法可以寻求较佳的关闭规律,使灯泡贯流式机组在甩负荷时获得较好的过渡过程,对保障电站安全稳定运行具有指导意义.

The power station of bulb tubular type turbine is characteristic of low head and large discharge.The transient quality of unit is impacted greatly by the close law of gates and blades during the large fluctuation after load rejection.The objective function for the transient composed of the unit＇s rotate speed rise,the water pressure at the gates＇ front and the axial hydraulic thrust was established and corresponding weight coefficients were determined.The orthogonal design calculation suitable for multifactor and multi-level was adopted to optimize the close law of unit.Specifying the first time of gates close,the second time,the inflection point of gates close and the close time of blades were appointed as factors.The orthogonal design calculation was implemented with four levels adopted for every factor.The results show that the transient quality such as the rotate speed rise,the water pressure at the gates＇ front,the axial hydraulic thrust and the water pressure at the draft tubes＇ inlet,are improved significantly under the optimal close law of gates and blades.The water hammer pressure in penstock and thevacuum degree at the draft tubes＇ inlet can be decreased in the case of blades closed slowly.The rotate speed rise of unit and the axial backward thrust can be notably reduced.A better close law can be obtained by the orthogonal design calculation so that the better transient of bulb tubular type turbine after load rejection would occur.It can provide guidance of ensuring safety and stable operation of power station.