I have implemented an EKF to estimate the dynamic state of a synchronous generator in Matlab/Simulink. The model of the generator is a 6th order sub-transient dynamic model. Ignoring the effects of saturation in the machine, I can achieve a good performance of the EKF. However, when I simulate the behavior of the machine including saturation, it results in an steady state error in my estimates.
How could I account for the effects of saturation in the estimation process? Or how could I reduce the steady state error when including saturation in the machine.