Proportional Band Research Articles

Optimization for Setpoints of Steam Generator Water Level Control Systems in Power-uprated YGN 1 & 2 and Kori 3 & 4

Korean nuclear industry has performed power uprating project for YGN 1&2 and Kori 3&4 to increase the plant licensed power by 4.5%. The power uprating of 4.5% changes the plant operating conditions. Particularly, it reduces the capacity of steam dump valves from 70 to 59.1% of turbine steam flow at the full power. Thus, we evaluated the bounding transient of 95% load rejection as a function of a proportional band (PB) of SDCS whether the steam dump capacity was sufficient to accommodate the increased thermal load without the modification of component. Also, we performed the sensitivity studies for a PB of SDCS and a KPFM of FWCS to determine the optimized setpoints of FWCS and SDCS which minimized the fluctuation of steam generator (SG) water level due to swelling and shrinking. From these analyses results, we determined the optimized setpoints of FWCS and SDCS in power uprated YGN 1&2 and Kori 3&4. After then, we verified the appropriateness of these setpoints through analyzing SG level setpoint step change and turbine power ramp change. These verification analyses showed that the revised control setpoints of SDCS and FWCS were appropriate all over the plant normal operation range. Therefore, in order to accommodate the increased thermal load and to modulate SG water level stable, it was appropriate that the PB of SDCS set to 15.0 and the KPFM of FWCS to 0.6 in power uprated YGN 1&2 and Kori 3&4.

STUDY ON OPTIMUM PID CONTROLLER SETTINGS FOR TEMPERATURE CONTROL IN A GROWTH CABINET

To obtain the criteria for the optimum setting of the PID controller of temperature, the effect of the setting combinations of proportional band (PB), reset time (TI) and rate time (TD) on the response characteristics in temperature control was analyzed by measuring the control area and the settling time in step response of air temperature in a growth cabinet (KG 208) . From the results, following points were made clear:1) The response characteristics were remarkably affected by PB setting; the PB was most responsible for the control area and the settling time.2) When PB was more than 50%, the control area and the settling time were very large, and in most cases, the temperatures were not settled during an hour.3) When PB was 3%, the cycling occurred in all cases, regardless of TI and TD settings.4) When PB was 10%, the control area and the settling time were very small. However, when TD was 2 min, the cycling occurred even when PB was 10%.5) Optimum setting was given when PB is 10%, TI=10-20 min and TD=0-0.5 min.