Grid-connected photovoltaic inverters with low-voltage ride through for a residential-scale system: A review

Background Recent advancements in solar power generation technology have paved the way for a vast number of photovoltaic (PV) systems integration into the grid network. The global installed capacity of rooftop PV systems has already surpassed a 50 GW mark in 2020, while the total installed capacity of all types of PV systems is reaching beyond 500 GW. The influx of distributed PV-generators must be equipped with sophisticated control to ensure grid stability, especially during grid faults. A devastating grid outage may occur if the grid-tied PV inverters are not equipped with the "fault-ride-through" mechanism. Many countries have already enforced a mandatory grid code which includes a low-voltage-ride through requirements for PV-generators. Aim and Objective This paper reviews the design of a rooftop PV inverters in the light of low-voltage-ride-through requirements. Materials and Methods For the implementation of low-voltage-ride-through (LVRT), the design of low-voltage-sag detection, grid-synchronization, filter-selection, and power-controllers are examined through simulations and literature survey. LVRT implementation issues are highlighted with an emphasis on the current controller performance during grid sags. Results and Discussion From the review and analysis conducted in this study, this paper concludes that ensuring a stable DC-link and appropriate control-reference-signals during the grid faults are the keys to the LVRT implementation. Conclusion In addition to robust power control, an autonomous PV generator should promptly detect the grid conditions and fulfils the ancillary services like LVRT, anti-islanding and flicker compensation. The recommendations and the future trends in the LVRT research conclude the review article.