Oscillation Detection on Offshore Oil Platforms Control Loops
Celso Jose Munaro1; Vinicius Belmuds Vasconcelos1; Débora de Souza Martins1; Paulo Emílio Altoe Targa2
1 Universidade Federal do Espírito Santo; 2 Petrobrás
Resumo
The presence of oscillations in control loops results in increased product variability and hence reduction of profitability. Oscillation detection on offshore oil platforms control loops is a challenge due to the presence of high amplitude non-oscillatory disturbances, causing distortions on spectra calculated by available methods in existent literature. In this article it is shown that the use of prefilters tends to eclipse low frequency oscillatory signals. A procedure for data segmentation is proposed to select data to be used for detection of oscillations. Considering that in such plants, many different and similar oscillations may result, an important step is also proposed to cluster similar frequencies and to keep only those that cause higher impact in the variance of the original signals. The methodology is applied daily during four days to 36 signals of an offshore oil platform, resulting in a reliable and easy to use report of oscillations that persist in subsequent analyzes, categorized by their impact.