水泵水轮机飞逸稳定性及其与反S特性曲线的关联
|
摘要
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.
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.
引文
1 Martin C S.Stability of pump-turbines during transient operation[C]∥Proceedings of the 5th International Conference on Pressure Surges,BHRA,1986.
2 Martin C S.Instability of pump-turbines with S-shaped characteristics[C]∥Proceedings of the 20th IAHR Symposium on Hydraulic Machinery and Systems,2000.
3 Olimstad G,Nielsen T K,Borresen B.Stability limits of reversible-pump turbines in turbine mode of operation and measurements of unstable characteristics[J].ASME Journal of Fluids Engineering,2012,134(11):111202.
4 Olimstad G.Characteristics of reversible pump-turbines[D].Trondheim:Norwegian University of Science and Technology,2013.
5 Nicolet C,AllignéS,Kawkabani B,et al.Unstable operation of Francis pump-turbines at runaway:rigid and elastic water column oscillation mode[C]∥Proceedings of the 24th IAHR Symposium on Hydraulic Machinery and Systems,2008.
6 Zhou J X,Karney B W,Hu M,et al.Analytical study on possible self-excited oscillation in S-shaped regions of pump-turbines[J].Proc.IMech E,Part A:Journal of Power and Energy,2011,225(8):1132-1142.
7 Staubli T,Widmer C,Tresch T,et al.Starting pump-turbines with unstable characteristics[C].Hydro 2010,Lisbon,Portugal,2010.
8 Drfler P K,Engineer A J,Pendse R N,et al.Stable operation achieved on a single-stage reversible pump-turbine showing instability at no-load[C]∥Proceedings of the 19th IAHR Symposium Section on Hydraulic Machinery and Cavitation,1998.
9 Widmer C,Staubli T,Ledergerber N.Unstable characteristics and rotating stall in turbine brake operation of pump-turbines[J].ASME Journal of Fluids Engineering,2011,133(4):041101.
10 Widmer C,Staubli T,Tresch T,et al.Unstable pump-turbine characteristics and their interaction with hydraulic systems[R].Hydro Vision,Charlotte,NC,2010.
11 张兰金,王正伟,常近时.混流式水泵水轮机全特性曲线S形区流动特性[J].农业机械学报,2011,42(1):39-43.Zhang Lanjin,Wang Zhengwei,Chang Jinshi.Flow of pump-turbine on S-shaped region of complete characteristics[J].Transactions of the Chinese Society for Agricultural Machinery,2011,42(1):39-43.(in Chinese)
12 Yin J L,Wang D Z,Wei X Z,et al.Hydraulic improvement to eliminate S-shaped curve in pump turbine[J].ASME Journal of Fluids Engineering,2013,135(7):071105.
13 刘启钊,彭守拙.水电站调压室[M].北京:中国水利水电出版社,1995.
14 Guo W C,Yang J D,Cheng J P.Research on critical stable sectional area of surge chamber considering the fluid inertia in the penstock and characteristics of governor[C]∥Proceedings of the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting,2014,1B:Vol BT10A033.
15 赵桂连,杨建东,杨安林.电气过渡过程对转速调节品质的影响[J].水力发电学报,2007,26(1):135-138.Zhao G L,Yang J D,Yang A L.The influence of electric transient process on speed regulation quality[J].Journal of Hydroelectric Engineering,2007,26(1):135-138.(in Chinese)
16 郭涛,张立翔.混流式水轮机尾水管近壁湍流特性和流场结构研究[J].农业机械学报,2014,45(9):112-118.Guo Tao,Zhang Lixiang.Numerical study of swirling flow fields in francis turbine under small opening condition[J].Transactions of the Chinese Society for Agricultural Machinery,2014,45(9):112-118.(in Chinese)
17 王旭鹤,祝宝山,樊红刚,等.水泵水轮机转轮三维反问题设计与特性研究[J].农业机械学报,2014,45(12):93-98,116 .Wang Xuhe,Zhu Baoshan,Fan Honggang,et al.3D inverse design and performance investigation of pump-turbine runner[J].Transactions of the Chinese Society for Agricultural Machinery,2014,45(12):93-98,116.(in Chinese)
2 Martin C S.Instability of pump-turbines with S-shaped characteristics[C]∥Proceedings of the 20th IAHR Symposium on Hydraulic Machinery and Systems,2000.
3 Olimstad G,Nielsen T K,Borresen B.Stability limits of reversible-pump turbines in turbine mode of operation and measurements of unstable characteristics[J].ASME Journal of Fluids Engineering,2012,134(11):111202.
4 Olimstad G.Characteristics of reversible pump-turbines[D].Trondheim:Norwegian University of Science and Technology,2013.
5 Nicolet C,AllignéS,Kawkabani B,et al.Unstable operation of Francis pump-turbines at runaway:rigid and elastic water column oscillation mode[C]∥Proceedings of the 24th IAHR Symposium on Hydraulic Machinery and Systems,2008.
6 Zhou J X,Karney B W,Hu M,et al.Analytical study on possible self-excited oscillation in S-shaped regions of pump-turbines[J].Proc.IMech E,Part A:Journal of Power and Energy,2011,225(8):1132-1142.
7 Staubli T,Widmer C,Tresch T,et al.Starting pump-turbines with unstable characteristics[C].Hydro 2010,Lisbon,Portugal,2010.
8 Drfler P K,Engineer A J,Pendse R N,et al.Stable operation achieved on a single-stage reversible pump-turbine showing instability at no-load[C]∥Proceedings of the 19th IAHR Symposium Section on Hydraulic Machinery and Cavitation,1998.
9 Widmer C,Staubli T,Ledergerber N.Unstable characteristics and rotating stall in turbine brake operation of pump-turbines[J].ASME Journal of Fluids Engineering,2011,133(4):041101.
10 Widmer C,Staubli T,Tresch T,et al.Unstable pump-turbine characteristics and their interaction with hydraulic systems[R].Hydro Vision,Charlotte,NC,2010.
11 张兰金,王正伟,常近时.混流式水泵水轮机全特性曲线S形区流动特性[J].农业机械学报,2011,42(1):39-43.Zhang Lanjin,Wang Zhengwei,Chang Jinshi.Flow of pump-turbine on S-shaped region of complete characteristics[J].Transactions of the Chinese Society for Agricultural Machinery,2011,42(1):39-43.(in Chinese)
12 Yin J L,Wang D Z,Wei X Z,et al.Hydraulic improvement to eliminate S-shaped curve in pump turbine[J].ASME Journal of Fluids Engineering,2013,135(7):071105.
13 刘启钊,彭守拙.水电站调压室[M].北京:中国水利水电出版社,1995.
14 Guo W C,Yang J D,Cheng J P.Research on critical stable sectional area of surge chamber considering the fluid inertia in the penstock and characteristics of governor[C]∥Proceedings of the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting,2014,1B:Vol BT10A033.
15 赵桂连,杨建东,杨安林.电气过渡过程对转速调节品质的影响[J].水力发电学报,2007,26(1):135-138.Zhao G L,Yang J D,Yang A L.The influence of electric transient process on speed regulation quality[J].Journal of Hydroelectric Engineering,2007,26(1):135-138.(in Chinese)
16 郭涛,张立翔.混流式水轮机尾水管近壁湍流特性和流场结构研究[J].农业机械学报,2014,45(9):112-118.Guo Tao,Zhang Lixiang.Numerical study of swirling flow fields in francis turbine under small opening condition[J].Transactions of the Chinese Society for Agricultural Machinery,2014,45(9):112-118.(in Chinese)
17 王旭鹤,祝宝山,樊红刚,等.水泵水轮机转轮三维反问题设计与特性研究[J].农业机械学报,2014,45(12):93-98,116 .Wang Xuhe,Zhu Baoshan,Fan Honggang,et al.3D inverse design and performance investigation of pump-turbine runner[J].Transactions of the Chinese Society for Agricultural Machinery,2014,45(12):93-98,116.(in Chinese)