A novel low voltage ride through strategy of two-stage grid-connected photovoltaic inverter

With the power of photovoltaic power plants becoming increasingly larger, low voltage ride-through capability of photovoltaic inverter have been required in many country. over voltages in dc side and over currents in ac side of photovoltaic inverter may occur when the grid voltage dips, which may lead to the problem of inverter dropping from the grid. This paper proposed a control strategy based on input and output power-balance for photovoltaic inverter. The max power point tracking strategy is disabled during the period of the grid voltage dip. The operation voltage was deviated from the max power point voltage, which reduced the input power of the inverter. The low voltage ride through requirement of photovoltaic inverter was achieved. In addition, the control strategy feasibility was verified by PSCAD/EMTDC simulation results.