汽轮机阀门关闭试验中的噪声分析和信号处理

在进行汽轮机汽阀关闭试验时，可能会发生阀位信号受噪声污染的现象，从而无法计算准确的关闭时间，严重影响汽轮机安全评估的可靠性。针对某电厂汽阀关闭试验中被污染的信号，采用快速傅立叶变换（fast Fourie transform，FFT）对信号的构成进行了分析，采用波形比较的方法对单一正弦分量污染下的关闭时间进行了计算；采用无限脉冲响应（infinite impulse response，ⅡR）数字滤波法对多频率正弦噪声分量影响下的信号进行了滤波，比较了不同滤波器的滤波效果并对滤波后的关闭时间进行了计算。结果表明，波形比较法可用于单一分量污染下的关闭时间计算，巴特沃斯（Butterworth）滤波器和切比雪夫（Chebyshev）Ⅰ型滤波器可用于多频率正弦噪声分量影响下的信号滤波，基于巴特沃斯滤波的汽阀关闭时间计算结果略优于切比雪夫Ⅰ型。

Noise Analysis and Signal Processing in the Turbine Valve Closing Test

The valve position signal may be contaminated by noise during the turbine valve closing test, which makes it hard to calculate the closing time accurately. As a result the reliability of turbine safety assessment will seriously be affected. In this paper, the components of the contaminated signal sampled in turbine valve closing test were first analyzed using fast Fourie transform (FFT). Then the accurate closing time was calculated by waveform comparison regarding the noise signal with single sinusoidal waveform component. Afterwards, the signal contaminated by multi-frequency sinusoidal noises was filtered by infinite impulse response (ⅡR) digital filtering method. The filtering effects of different filters were compared and the closing time after the filtering were calculated. It is suggested the waveform comparison method is very suitable for the computation of closing time with the signal contaminated by single component sinusoidal waveform. Both the Butterworth filter and Chebyshev I type filter can be used for signals contaminated by multi-frequency sinusoidal noises, while the former is slightly better than the latter regarding the accuracy of calculation results.