Patent Number: 040615332
Section: summary

This invention relates to a control system for a nuclear power producing unit having a reactor in which a coolant, such as water under high pressure, is heated and circulated in parallel through a plurality of steam generators supplying steam to a prime mover such as a turbine generator. As an order of magnitude, the reactor in such a unit may have a heat output of upwards of 3,400 Mw and a net electric output of 1,200 Mw. In accordance with the invention a primary feed forward control signal corresponding to the desired or demand power output adjusts, in parallel, through separate discrete control loops, the reactor heat output required to satisfy the power demand, and the total rate of feedwater flow to and steam flow from the steam generators required to maintain critical system parameters at set point. Further in accordance with the invention the feed forward control signal to each discrete control loop is modified by the time integral of the difference between demand and actual power outputs to thereby continuously calibrate, under steady state conditions, changes in reactor heat output required to satisfy the power demand because of changes in cycle efficiency and the corresponding changes in total rate of feedwater flow to and steam flow from the steam generators required to maintain critical system parameters at set point. Further in accordance with the invention the feed forward control signal to each discrete control loop is further modified in proportion to transient changes in the difference between demand and actual power outputs and critical system parameters. Further in accordance with the invention the relative rates of feedwater flow to the steam generators are additionally adjusted in proportion to changes in the relative rates of coolant flows through the steam generators. Further in accordance with the invention the relative rates of feedwater flows to the steam generators are further adjusted in accordance with the difference in temperatures of the feedwater entering the steam generators. Further in accordance with the invention the relative rates of feedwater flows to the steam generators are additionally adjusted in accordance with the time integral of the difference between the average coolant temperatures in the steam generators. These and further objectives of the invention will be apparent as the description proceeds in connection with the drawings, in which: