| 摘要 |
A method and apparatus for controlling the rate of supply of a first substance (for example sulphur dioxide or chlorine) to a fluid (for example water). The method comprises determining a supply rate parameter B from an input error parameter E indicative of the difference between a desired concentration R of a second substance in the fluid and a measured concentration C of the second substance in the fluid. The supply rate parameter is calculated by summing a proportional term updated at predetermined time interval T 1, an integral term updated at predetermined time interval T 2 and a correctional term CT at predetermined time interval T 3, T 2 is longer than TI, and also longer than T3. The correctional term is determined based upon the current value of E, the previous value of E, the desired concentration R and the measured concentration C. The correctional term increases the speed of response of the controller to changes in the desired concentration and reduces the amount of oscillation during changes in the supply rate parameter. The controller may be a Proportional - Integral (PI) controller. |
