Modal Identification and Analysis of Photovoltaic Converter Based on Random Subspace

Abstract

A large number of photovoltaic grid-connection brings many harmonic resonance problems to the power grid. A joint model including photovoltaic converter and grid equivalent impedance was established for the photovoltaic converter resonance problem. The s-domain model of photovoltaic converter impedance and grid impedance was derived. The photovoltaic output current contains not only the voltage frequency component but also the resonant component of the photovoltaic impedance by using the inverse Laplace transform. The stochastic subspace method was used to analyze the modal components of photovoltaic grid-connection points and currents. The impedance modes of photovoltaic converters were extracted according to the difference between the two modes. Finally, the effectiveness of the proposed method was verified by simulation and experimental data analysis.

Keywords

• photovoltaic
• converter
• equivalent impedance of power grid
• resonance
• stochastic subspace
• mode