The increasing penetration of photovoltaic (PV) energy in power grids will impose system instability issues, especially in the occurrence of faults. However, very limited research has been conducted on the low-voltage ride-through (LVRT) control of PV systems in the low-voltage distribution networks (LVDNs) with predominantly resistive line impedances. To fulfil this remaining gap, the effects of active current injection (ACI) on the grid voltage support in LVDN is mathematically analysed in this study. Subsequently, a novel LVRT control scheme for the PV grid-forming inverter is proposed, where the control distinguishes itself from other existing methods due to its optimisation of ACI and PV energy harvesting with the premise of system safety and specified reactive current injection as per grid codes. Multi-mode control modes are involved in the proposed method for dealing with different environmental conditions and voltage dips. Meanwhile, the DC-link voltage is adaptively operated in a self-adjustable control structure for improving grid resilience. The effectiveness of the proposed control method is verified by simulations in MATALB Simulink and hardware experiments on a PV microinverter. Compared with the traditional LVRT control, the post-fault power recovery and voltage support capability can be significantly improved.
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment