| Steam generator is an important heat exchanger in nuclear power plant, which is called the hinge of nuclear and conventional island. Steam generator level is a non-linear, mutative and multi-variable system. It is a problem to design the control system because of"false level". The cascade PID control system of steam generator level is prevalent used in industry. However, limited by the technology development, it do not make its best effect.Based on the steam generator operation principle, expert knowledge of the related field and operation experience on site, we analyze in theory to the dynamic character of"false level"during transient, Then point out the deficiency of the cascade PID control system and the progress of main and bypass valve switching. To the steam fluid measurement, the way to estimate the fluid for steam based on the balance of Steam Generator and compensate of steam flux coefficient, in allusion to the problem of low measure precision in low power. In the course of the design of the program for valve switch, we calculate not only the effect of feedwater as a result of nonlinear characteristic of regulate valve, but also the effect of sluggish, deadband and leakage in real state. Then, we point out the way of loop control to make sure the bumpyless during valve switch process.The phenomena of"false level"which is occurred in power transient, it can not be measured by routine method. As"false level"take place at instant state of non- harmony of gas and liquid, this article use interrelated principle to measure the pertinence of the flux of steam and feedwater, and to estimate the"false level". Thus, we use the idea of Model Predictive Control to design the state estimator based on knowledge of Kalman filter, which can be used to observe and find the"false"component of steam generatorlevel. After eliminating those components from feedback of cascade PID control system, itis confirmed and validated on the simulation software Labview.
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