| 摘要 |
<p>In a computer-controlled process, a method using an algorithm-controlled monitoring of disturbances apt to occur at random or in bursts in the process is performed. Counting values are used, that are obtained from a counter for counting said disturbances. The method starts by defining an abnormal event regarded to be a disturbance. In a second step a base against which disturbance are to be counted is defined, followed by defining a unit to be used as a measure of a disturbance frequency. Then there are determined values of the disturbance frequency in a variety of circumstances that can be excepted in operation of a process generating the disturbance to be monitored, said values including a critical value fC of the disturbance frequency where the monitoring nominally issues an alarm. At said critical value there is determined for the process, a peakedness factor F, being a measure of how bursty the disturbances are, as the ratio of the variance to the mean of occurrences of disturbances in the process. For the algorithm an inertia value J is chosen that is a measure of how fast or slowly the algorithm is desired to react to changes in the disturbance frequency, so as to achieve an acceptable compromise between speed and reliability of the monitoring. Parameters are calculated for the monitoring based upon the disturbance frequency value fC, the peakedness factor F and the inertia value J, and the parameters are used to calculate according to 1/fC*J*F a threshold value T of the counter considered to be unacceptable. The algorithm for the monitoring is designed with said parameters, the monitoring is initiated and results thereof are awaited. Finally, the results are evaluated and, if necessary, the parameters are adjusted.</p> |
