Synchronous Reference Frame PLL Frequency Estimation under Voltage Variations

In this paper, MIMO space state models that represent the voltage influence in the SRF-PLL over its frequency estimations is obtained. Throughout the model development, two estimation alternatives were explored. The model accuracy was verified by simulations of the linear models and then compared with the nonlinear models. The SRF-PLL linear model represents well the behavior under single and three phase voltage sags.