Analyzing behaviors of three-level PV inverter based on multivariate phase space reconstruction

In this paper, system description of a photovoltaic powered three-phase Neutral-Point-Clamped (NPC) inverter is firstly analyzed for the sake of establishing simulation. Based on perturbation & observation method for maximal power point tracking and proportional-integral control, the simulation is carried out to explore the operational system behaviors. The curves of output variables and their phase trajectories are comparatively depicted. Based on sampled multivariate time series, mutual information and false nearest neighbor methods are introduced to determine the delay time and embedding dimension for reconstructing the phase space, based on which, the largest Lyapunov exponent and fractional dimension are calculated to characterize the chaotic behavior of this photovoltaic powered three-level inverter. The simulation results also show that the system parameter variation has significant impacts on the operational performance of inverter system, which implies that suitable control method is required to eliminate unexpected influences.