| 摘要 |
<p>A method for determining when a process variable output signal is in a steady state or in a non-steady state condition, wherein the signal detection technique is dependent upon power spectral densities. Reference data is established by first sampling a plant's process variable output signal when the plant is operating at steady state. The sampled output signal is then analyzed to derive the reference data that includes an energy content of each of a plurality of its frequency components. A current operational data base is then established by sampling a process variable signal when the plant is in operation. The sampled current output signal is analyzed to derive current data that includes an energy content of each of a plurality of its frequency components. For each common frequency component of the reference data and the current data, the system makes a comparison of the energy contents and issues a non-steady state signal if the comparison indicates that the compared energy contents exceed a predetermined limit.</p> |
