带分流叶片水泵水轮机甩负荷过渡过程中的压力脉动特征OA北大核心CSTPCD
Characteristics of pressure fluctuation in pump turbines with splitter blades during the load rejection transient process
为减轻水泵水轮机过渡过程中剧烈压力脉动对抽水蓄能电站安全产生的不利影响,需充分认识水泵水轮机的压力脉动特征.本文对某带分流叶片水泵水轮机甩负荷过渡过程中的实测压力脉动数据开展深入研究.首先从压力脉动的频域特性出发,提出了一种基于变分模态分解的时均压力和脉动压力提取方法.然后采用傅里叶变换和短时傅里叶变换分析水泵水轮机稳定运行和甩负荷过程中蜗壳进口、无叶区、顶盖和尾水锥管进口的脉动压力,揭示了带分流叶片水泵水轮机在稳定运行和甩负荷过渡过程中压力脉动的频率组成和时频变化特性的普遍规律.研究表明,带分流叶片水泵水轮机无叶区压力脉动的主频由叶片通过频率及其半次谐波共同主导,且叶片通过频率的半次谐波具有向上下游传播的特点.尾水锥管进口压力脉动频率主要由低频成分及叶片通过频率的半次谐波构成.甩负荷过渡过程中,无叶区叶片通过频率及其谐波的频率会随着时间的变化出现增大和减小现象,且变化规律与转轮转速的变化趋势一致.本文所提出的方法为压力脉动实测数据分析提供了一种新手段,为带分流叶片水泵水轮机压力脉动的特征研究提供了参考与借鉴,对结构异常振动溯源和保障机组安全运行具有重要意义.
In order to reduce the adverse effects of severe pressure pulsations generated during the transition process of the pump turbine on the safety of pumped storage power stations,it is necessary to fully understand the characteristics of pressure pulsation of pump-turbine.This paper conducts an in-depth study on the measured pres-sure data of the pump-turbine with splitter blades during the load rejection transition process.First,a method for extracting time-average pressure and pulsating pressure based on variational mode decomposition(VMD)is presen-ted based on the frequency domain characteristics of pressure pulsations.Then,Fast Fourier Transform(FFT)and Short Time Fourier Transform(STFT)are used to analyze the pulsating pressure at the spiral casing inlet,vaneless area,top cover,and draft tube cone inlet during the stable operation and load rejection of the pump turbine.The general behaviors of frequency composition and time-frequency variation features are revealed during the transition period of steady operation and load rejection of pump turbines with splitter blades.The research shows that the main frequency of the pressure pulsation in the vaneless area of the pump turbine with splitter blades is dominated by the blade passing frequency(BPF)and its half-order harmonics,and the half-order harmonics of the BPF have the characteristics of upstream and downstream propagation.The draft tube inlet pressure pulastion frequency is mainly composed of the low frequency component and the half-harmonic of the BPF.During the load rejection transition process,the BPF and its harmonic frequency in the vaneless area will increase and decrease with time,and the change rule is consistent with the change trend of the runner speed.The method provided in this research presents a novel approach for analyzing collected pressure pulsations and provides a reference for the study of the pressure pul-sation characteristics of pump turbines with splitter blades.It is of great significance to trace the source of the ab-normal vibration of structure and ensure the safe operation of the units.
周廷鑫;俞晓东;张健;徐辉
河海大学水利水电学院,江苏南京 210098
水利科学
分流叶片水泵水轮机过渡过程压力脉动信号处理
pump-turbine with splitter bladestransition processpressure pulsationssignal processing
《水利学报》 2024 (009)
1098-1109 / 12
国家自然科学基金面上项目(52179062,51839008)
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