Computer predictions of the behaviour of digital control systems

The automatic station control system for Heysham 2/Torness nuclear power stations are implemented by a distributed computer control system incorporating direct digital controllers (DDC). A two-stage approach was adopted in the design of a viable automatic control system; firstly an equivalent continuous-time control system representation was generated within a non-linear total-plant model, and secondly improvements were made if and where necessary with explicit DDC representations within the model. Comparisons of computer predictions using both continuous-time and direct digital control systems are presented together with results of computer predictions from the direct digital control system and actual plant responses from the Torness nuclear power station. (author)