Sizing Approach for a Single-Phase Grid-Connected Photovoltaic Converter with Active and Reactive Power Management

This paper proposes a sizing approach for the passive components of a photovoltaic (PV) full-bridge dc-dc converter connected to a full bridge inverter and an LCL filter with grid connection. An expression for the PV capacitor is derived from the rms voltage equation at the terminals of the PV array. A polynomial method based on a frequency domain analysis of the LCL circuit is developed to select the inductance values of the filter. A damping resistance is added in series with the filter capacitor to reduce the resonance peak and to improve the stability margin of the control system. The dc-link capacitor is obtained from an expression that calculates the ripple magnitude of the second order harmonic, and its sizing takes into account not only the active power processed, but also the maximum amount of reactive power that the converter will manage. The control scheme has three objectives: the maximum power extraction from the PV array, the dc-link voltage regulation, and both active power injection and reactive power management interacting with the grid. The proposed sizing procedure is validated via simulation in a 1.41 kVA converter.