Three-level T-type inverter (3LT2I) has been widely applied in photovoltaic (PV) system. When the grid fault occurs, the low-voltage ride-through (LVRT) and high-voltage ride-through (HVRT) capabilities of 3LT2I are the key to increase the safety and reliability of the system. However, the switch fault of 3LT2I is easy to occur in LVRT/HVRT operation due to the overcurrent. And the existing fault tolerant control (FTC) strategies are not applicable to the grid fault conditions. Therefore, this paper proposes an FTC strategy for 3LT2I in LVRT/HVRT operation. First, the negative sequence component of grid voltage is injected into the modulation waveforms and the active/reactive currents are modified to realize the fault ride-through. Second, the impossible vectors caused by the switch fault are abandoned to realize FTC. Then, the available vectors are selected according to the three-phase current polarities and the duty cycles where a compensation is introduced are calculated to realize the NP voltage oscillation suppression. Finally, simulations and experiments verify the validity of the proposed strategy.
