Two-level Active Fault Tolerant Control approach

In this paper, a two-level reconfiguration action is used to design an Active Fault Tolerant Control (AFTC) system. The first level of the procedure is triggered when the impact of the fault on the system performance is limited. The reconfigurable controller is updated by the new post-fault system model. At the second level a dynamic reference modification based on Reference Governor (RG) is proposed. The idea consists of modifying the set-point or reference according to the allowable performance degradation and the system constraints which become more strict after fault occurrence in order to avoid any actuator saturation and ensure system stability. The effectiveness of the proposed solution is illustrated by a wind turbine example subjects to actuator faults and constrained on the actuator dynamic ranges.