Improved nonlinear turbine-governor model and parameter assessment for a large hydropower plant

摘要

In the presented power system analysis software, the actuator model of hydro turbine governor system cannot effectively reflect the actual characteristics of the section closing law. The accuracy of Francis turbine model simulation is not high since the Francis turbine static characteristic curve between turbine power and guide vane opening is obviously nonlinear under a certain water head. An improved actuator model was proposed with section closing rate limits, which reflects the section closing law of the guide vane. The simulation analysis shows that the section closing point has a great effect on the Francis turbine in case of load rejection when the vane is fully closed. Compared with different fitting methods of the mechanical power and guide vane opening, the cubic polynomial fitting method is more suitable and recommended. An improved nonlinear turbine model with nonlinear characteristics of mechanical power versus gate position was established. The comparison between the simulation and field test data demonstrates that the improved nonlinear Francis turbine-governor model considering section closing law of guide vane is more practical and effective than the existing models, thus can be better applied in power system simulation analysis.