Time-frequency feature extraction from multiple impulse source signal of reciprocating compressor based on local frequency

Vibration signals generated by reciprocating compressor present a multiple impulse source property, which is typical non-stationary. For this kind of signal, time-frequency analysis techniques, such as STFT, WVT, WT and HHT, represent some limitations. To alleviate this problem, a novel concept of local frequency (LF) is proposed in the paper. Based on the concept, a time-frequency distribution algorithm is established. Some non-stationary simulation signals, including multi-harmonic signal, FM signal and multiple impulse source signal, are investigated to identify the feasibility and effectiveness of the novel time-frequency analysis technique. Compared with WVT, WT and HHT, time-frequency analysis based on LF represents a higher resolution and more useful information. Moreover, the proposed approach is applied to the fault feature extraction of reciprocating compressor gas valve vibration signal in normal valve state and gap valve state. The results indicate the superiority of proposed approach in extracting time-frequency features from multiple impulse source signal of reciprocating compressor, which obtains a more precise result than WVT, WT and HHT. So it can provide an effective basis to fault diagnosis of reciprocating compressor.