水电机组振动与压力脉动峰峰值算法对比研究

Methods comparison for calculating peak-to-peak amplitudes of vibrations and pressure pulsations in hydropower units

运行稳定性参数的准确获取是水电机组状态监测与故障诊断的重要基础,其中振动与压力脉动峰峰值是众多稳定性参数中的核心。文章首先梳理了各标准中不同水电机组振动测点峰峰值计算方法,对置信区间算法概念进行了剖析,指出了工程应用与统计学概念上存在的歧义;其次采用不同噪声条件下的仿真信号对各算法适用性进行了验证;考虑现场测试信号的复杂性,采用实测信号对不同的算法性能进行了分析。研究表明:对于低频分量占主要成分的信号,±1.96倍标准差算法与仿真和实际信号峰峰值偏差大,不应采用;对于含有明显高频成分的信号,不同算法之间存在显著差异;推荐采用95%置信区间算法计算各种信号的峰峰值,该方法计算结果保守,但具有鲁棒性强、对噪声不敏感的优点。研究结果为GB/T 17189、IEC 60994及相关ISO相关标准的修订提供了技术支撑。

Collecting accurate data of stability parameters is a key to monitoring and fault diagnosis of hydropower units, particularly the core stability parameters： peak-to-peak amplitudes of vibrations and pressure pulsations. First, this paper examines different methods for calculating peak-to-peak values specified in different standards and discusses the concept of confidence interval from the two viewpoints of statistics and engineering application. Then, considering signal collection in a complicated field environment, we verify each method using both numerically simulated signals with normally distributed noises and field measurements. Results show that for low frequency dominated signals, the ±1.96σ method produces large errors and thus is not applicable, while for signals with high frequency components, different methods often result in great differences. This study recommends the method of 95% confidence interval for calculation of peak-to-peak values of the signals, which is conservative but robust and insensitive to noises. These results would help the revision of GB/T 17189, IEC 60994 and other related ISO specifications.