Research On Pressure Control Of The Once-Through Steam Generator

Steam generator (SG), an important heat exchanger that connects pressured water reactor's primary loop with secondary loop, is considered that the intersection of primary loop and secondary loop. The main function of steam generator is transferring the heat from the reactor core carried by primary side coolant to secondary side water through U-tube, then secondary side water change into steam which is carried to the turbine.Steam generator can be divided into natural circulation steam generator and once-through steam generator. This object of study is the helical coil once-through steam generator. Its pressure control has a direct effect on steam quality and the safety of steam generator. Therefore it is important and necessary for us to control and it is valuable to have study on pressure control.Physical process of once-through steam generator is a very complex process. It is provided with nonlinear, parameter variability and uncertainty characteristics of the various disturbances, so it is hard to control pressure of once-through steam generator satisfactorily by traditional PID methods. On the basis of analyzing in depth the principle of the neural network,the paper has researched on the applications of neural network in control system, making use of it self-1earning ability. Based on PSD algorithm,the paper proposes the gain adaptive algorithm, to make the gain of the controller have self-adaptive ability.It has excellent robustness characteristics. It is fit for the pressure control of once-through steam generator.Then the proposed strategy is applied to pressure control of the helical coil once-through steam generator, the results of simulation show that under this control strategy the system may overcome the disadvantageous influence and it has smaller maximum overshoot than the cascade feedforward-feedback control system.