Nonlinear Multiscale Modeling of Multi-Machine Power Systems Integrated with Photovoltaics

Large-scale photovoltaics (PVs) connected to the power grid through power electronic equipment have greatly changed the dynamics of the traditional power systems dominated by synchronous generators (SGs), bringing significant challenges to modeling and analysis of modern power systems. In this paper, a nonlinear model of multi-machine power systems integrated with PVs is established to reveal the multi-timescale transient synchronization characteristics using the singular perturbation technique. The fast subsystem containing the dynamics of the DC voltage control, terminal voltage control, and phase-locked loop, and the slow subsystem containing the dynamics of the rotor swing can effectively reflect the dynamics of multi-machine power systems integrated with PVs within the electromagnetic and electromechanical timescales, respectively. The proposed model provides a clearer physical picture of dynamics in the multi-machine power systems integrated with PVs within the electromagnetic and electromechanical timescales, and serves as the foundational model for further stability analysis. Finally, simulation results verify the validity of the proposed model.