Effect of detailed hydro turbine models on power system analysis

Simplified ideal models of hydro turbines are applied in power system simulation, while the effect of detailed model of hydro turbine on simulation results of power system analysis remains to be solved. The authors present four models of hydro turbine, including the nonlinear analytical hydro turbine model, the linearized model based on the prototype characteristics, the linearized model based on the internal characteristics, and the ideal model. The effect and the applicability of different detailed models of hydro turbines on power system analysis are compared and analyzed on a test system. The simulation results show that For power system transient stability analysis, the effect of different detailed hydro turbine models is not evident, and the transient process of the power system is not always a large disturbance to the hydraulic system. The effect on the hydraulic variables is more than the effect on the electrical variables. For power system small signal stability analysis, the electro mechanic oscillation mode has some correlation with the hydraulic oscillation mode. The four different hydro turbine models have much effect on the electro mechanic oscillation mode and the hydraulic oscillation mode, and have little effect on the excitation system oscillation mode. The damping coefficients of the oscillation modes vary a little when the operating points change. The damping coefficients at low power operating pint of the linearized hydro turbine model base on the prototype characteristics will have some error.