水泵水轮机飞逸稳定性及其与反S特性曲线的关联

Runaway Stabilities of Pump-turbines and Its Correlations with S Characteristic Curves

抽水蓄能电站的安全稳定运行与水泵水轮机反S特性直接相关。在电站甩负荷工况下,时有发生调速器事故,导致水泵水轮机导叶拒动,使机组进入飞逸工况。而由于水泵水轮机的反S特性会使得机组参数不能像常规水轮机一样快速收敛,甚至出现振荡的现象,导致事故进一步扩大。针对布置有下游调压室的抽水蓄能电站,采用线性化处理方法获得了水泵水轮机反S特性曲线的传递函数,并建立了流道-水轮机-发电机耦合的常微分数学模型,并进一步推导了水泵水轮机飞逸工况稳定性的判别条件。结果表明飞逸振荡的现象由多种因素共同决定,其中水泵水轮机飞逸点的曲线斜率为关键因素。利用已建立的物理模型平台,对这些影响因素进行了分析,并验证了所得的理论分析结论。

Pumped-storage stations can store energy and generate power according to load fluctuations, and play an important role as efficient ＂and effective regulators in the electric grid. The safety and stability of pumped-storage station are directly related to S characteristics of pump-turbines. When pump-turbines reject their load, servomotor often fails with uncertain issues, thus leading to guide vane closing failure and the unit will go into runaway operations with high rotational speed. Pump-turbine S characteristics, however, will prevent unit parameters from converging to constants as normal Francis turbines, thus aggravating the accidents with some harmful oscillations. This phenomenon occurred in pumped-storage stations installed at the downstream surge tank was studied. The linearization method of pump-turbine characteristics was adopted to gain the transfer coefficients of pump turbines. Then, a coupling mathematic model composed of pump-turbines, conduits, surge tank and generators was established based on matrix method. It was used to deduce the stability criterion of runaway operations. It can be concluded that the runaway oscillation of pump-turbines was caused by a couple of factors, in which the slopes of characteristic curves at the runaway point were dominated. Model tests were conducted on a model pumped-storage station in the laboratory which is composed of nine sub-systems. The model data of runaway conditions of two different pump-turbines were gained, and the conclusions of the theoretical analyses were validated.