Abstract
This work proposes a novel post-fault maximum power point tracking (MPPT) control scheme for fixed-pitch hydrokinetic turbines (HKTs). The proposed scheme leverages an existing 4th-leg fault-tolerant converter topology to enable long-term, power-derated operation after a single-phase fault, a condition where standard control approaches are unsuitable for HKTs. Unlike strategies focused on short-term survival, the proposed approach intelligently adjusts the turbine's operating point to manage component stress while maximizing energy capture. The controller's practicality is verified with Hardware-in-the-Loop (HIL) simulations, demonstrating stable fault transition and post-fault operation under realistic hydrodynamic conditions. Furthermore, a comprehensive multi-physics evaluation framework, utilizing a one-year water mission profile, is developed to quantify the system's impact on reliability and cost-effectiveness. The results provide a quantitative basis for optimizing HKT maintenance schedules and show that the fault-tolerant system achieves a 22.83% increase in annual energy generation compared to a non-fault-tolerant system with seasonal maintenance.