Nuclear Technology / Volume 185 / Number 3 / March 2014 / Pages 239-258
Technical Paper / Fission Reactors / dx.doi.org/10.13182/NT12-130
The Canadian supercritical water-cooled reactor (SCWR) can be modeled as a multiple-input multiple-output system. It has a high power-to-flow ratio, strong cross coupling, and a high degree of nonlinearity in its dynamic characteristics. Because of the existence of strong cross coupling among system inputs and outputs, it is difficult for a traditional control system design methodology to produce a satisfactory control system. In this paper, the direct Nyquist array method is used first to decouple the system into a diagonally dominant form via a precompensator. After decoupling the system successfully, three single-input single-output dynamic compensators are synthesized in the frequency domain. By using the precompensator, the temperature variation because of disturbances at the reactor power and pressure is significantly reduced. The control system can effectively maintain the overall system stability and regulate the plant around a specified operating condition. To deal with the nonlinearities, a control strategy based on gain scheduling is adopted. Different sets of controllers are used for the plant at different load conditions. The proposed control strategies have been evaluated under various operating scenarios. The robustness of the controller with respect to operating condition changes is also investigated. It is shown that the decoupling control can effectively reduce the cross coupling inherent in the Canadian SCWR, and gain scheduling control can successfully achieve satisfactory performance for different operating conditions.