Decoupled active and reactive power predictive control of impedance source microinverter with LVRT capability

Abstract

This paper presents a decoupled active and reactive power predictive control for quasi-Z-source (qZS) single-phase grid connected photovoltaic (PV) microinverter with low voltage ride through (LVRT) capability. The control algorithm structure is based on model predictive control (MPC) framework to facilitate switching between modes of operation: maximum power point tracking (MPPT) and LVRT modes. The proposed controller extracts the maximum power from the PV panels during the normal grid condition. The system is capable of injecting reactive power based on LVRT requirements by the grid codes based on commanded reactive power injection strategy. The proposed algorithm has simple structure with less complexity and computational time for easier and effective implementation. It can respond to rapidly changing PV ambient and grid conditions and appropriately alter the current injection. The performance of the controller is verified experimentally for three reactive power injection strategies.