Th USODA (U-tube Steam Generator Optimal Controller Design Analysis) code was developed to simulate the transient behavior of a vertical natural circulation U-tube steam generator in PWRs and to design the optimal level controller.
The linear steam generator model and optimal control theory were used in the model. The steam generator was represented by 6th order linear differential equations through matrix reduction.
The momentum equation for the recirculation flow implements the effects of the separators, U-bend regions, and spatial acceleration. To assure stability, Lyapunov theorem was adopted. The optimal gains were obtained by minimizing the quadratic performance index and by using both the Newton-Raphson and Successive Overrelation (SOR) methods.
By taking the advantages of both methods, fast converging was achieved.
Sample calculation for KNU-2 showed that a control system consisting of standard proportional and reset controls on water level deviation from a desired setpoint and of proportional control on the difference between steam and feedwater mass flow rates can be successfully employed for the control of water level. The optimization procedure led to a stable system with good controlled response.
Also it was shown that the system response can be adjusted to suit the system designer by varying the level weighting.
가압 경수형 원자력 발전소의 과도상태에 증기 발생기의 거동을 열수력적으로 묘사하여 증기발생기 내의 수위를 최적으로 조절하는 전산 프로그램(USODA)을 개발하였다. 이 전산 코드의 기본모형 은 6차 선형 미분 방정식으로 나타낸 증기 발생기의 열수력 모형과 최적 제어 이론으로 구성하였다. 여기에는 seperator, U-bend region 및 spatial acceleration의 효과를 나타내기 위하여 recirculation flow에 대한 운동량 방정식이 고려되었으며 제어계의 안정성을 위해 Lyapunov 이론이 도입되었다. 또한 최적의 gain을 얻기 위해 quadratic performance index를 최소화시켰으며, Newton-Raphson 및 SOR 방법을 사용하여 계산의 수렴을 빠르게 하였다.
KNU-2 발전소를 대상으로 시산한 결과 본 전산 프로그램은 수위 조절에 있어 안정된 제어를 보였다.
