In the paper a synthesis of advanced control structures of turbine and synchronous generator for nuclear power plant working under changing operating conditions (supplied power level) is presented. It is based on the nonlinear models of the steam turbine and synchronous generator cooperating with the power system. The considered control structure consists of multi-regional fuzzy control systems with local linear controllers, including PID controllers, in particular control loops of turbine and generator. Soft switching between the local controllers is performed by the Takagi-Sugeno-Kang fuzzy logic mechanism. Parameters of the local controllers were optimally tuned for a priori chosen operating points within the range of 50-100% of nominal active power generated by the synchronous generator. Simulation results show that proposed advanced control structure is superior to widely used classic control structure (local controllers tuned for nominal operating points). During simulations the data of the real devices was used, respectively for the 4 CK 465 steam turbine and synchronous generator GTHW-600, which were planned to be used in the first Polish nuclear power plant in Żarnowiec.

The paper presents the dynamic multivariable model of Nuclear Power Plant steam turbine. Nature of the processes occurring in a steam turbine causes a task of modeling it very difficult, especially when this model is intended to be used for on-line optimal process control (model based) over wide range of operating conditions caused by changing power demand. Particular property of developed model is that it enables calculations evaluated directly from the input to the output, including pressure drop at the stages. As the input, model takes opening degree of valve and steam properties: mass flow and pressure. Moreover, it allows access to many internal variables (besides input and output) describing processes within the turbine. The model is compared with the static steam turbine model and then verified by using archive data gained from researches within previous Polish Nuclear Power Programme. Presented case study concerns the WWER-440 steam turbine that was supposed to be used inŻarnowiec. Simulation carried out shows compliance of the static and dynamic models with the benchmark data, in a steady state conditions. Dynamic model also shows good behavior over the transient conditions.

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