LVRT Strategy Considering Reactive Power Support and Fluctuating Power Suppression for Photovoltaic Application

Addressing the insufficient negative sequence dynamic reactive current support and power doubling oscillations present in conventional low-voltage ride through control mechanisms for photovoltaic inverters, this study designs a q-axis command for both positive and negative sequence currents in accordance with recent regulatory requirements for photovoltaic grid integration technologies. The d-axis commands for positive and negative sequence currents are computed to effectively attenuate second harmonic fluctuations in active power output. The proposed approach establishes equilibrium between inverter current carrying capacity and oscillation mitigation, thereby concurrently enhancing dynamic reactive current support for both sequence components while diminishing power doubling fluctuations. The short-circuit current characteristics of photovoltaic installations are examined utilizing this enhanced low-voltage ride through control methodology. Comparative analysis between the suggested approach and current low-voltage ride through control techniques was conducted via simulation models, confirming both the efficiency of the proposed method and the accuracy of analytical expressions for short-circuit current.