Three-Phase Grid-Connected Photovoltaic Switched Boost Inverter with Low-Voltage Ride-Through Capability

The recent trends of the high level of penetration of photovoltaic (PV) systems with the grid, due to increasing load demands and continuous depletion of conventional energy sources, have attracted more extensive research in this area. Generally, PV systems utilize two-stage topologies which suffer from less efficiency, poor dynamic behavior etc. So, in this paper, the three-phase switched boost inverter (SBI) has been adopted, as a single-stage topology, to integrate PV system and the grid. Additionally, it has advantages over classical voltage source inverter (VSI) such as satisfying both dc and ac load requirements simultaneously, a wide range of output ac voltage, the capability to allow shoot-through, superior protection against electromagnetic interference (EMI) noise etc. With the help of a maximum power point tracking (MPPT) algorithm, Incremental Conductance method, the SBI extracts maximum available power from the PV system. In order to achieve accurate tracking of the grid current, the proportional resonant (PR) has been chosen as current controller which is coupled with harmonic compensator (HC) for superior harmonic performance. According to many updated grid standards, PV systems should incorporate low-voltage ride-through (LVRT) capability, i.e., to support the grid under fault conditions. Hence, the proposed system, called PVSBI in this paper, uses a control strategy to work with both MPPT and LVRT mode of operation. The three-phase PV-SBI has been verified in normal grid conditions, as well as balanced and unbalanced grid voltage sag conditions, using PSCAD/EMTDC.