Fault-Tolerant Permanent Magnet Synchronous Generator Drives for Wind Turbine Applications

摘要

This thesis intends to present new solutions for extending the reliability and availability levels of wind energy conversion systems based on permanent magnet synchronous generator (PMSG) drives. Therefore, fault-tolerant power converters for PMSG drives with the ability to handle open-circuit faults and current sensor faults are developed and proposed. By considering distinct control strategies, diagnostic techniques and converter topologies for post-fault operation, a wide range of solutions for fault-tolerant PMSG drive can be adopted with the contribution of this work. Firstly, taking into account that a standard PMSG drive is composed of two power converters in a back-to-back topology, four of the most broadly adopted control strategies for each converter are addressed in detail and their normal and faulty operation is analyzed by means of simulation and experimental results, permitting to verify the merits of each strategy under normal operation and to evaluate the fault impact. Having recognized that currents and reference voltages are suitable quantities to perform fault diagnosis, current- and voltage-based approaches are proposed in a total of six algorithms for open-circuit fault diagnosis and one algorithm for current sensor fault diagnosis. These techniques demonstrate high effectiveness and robustness, without requiring additional measurements or high computational effort. With the aim to handle open-circuit faults by employing non-redundant converters, alternative converter topologies and respective control strategies are necessary for post-fault operation. Accordingly, four topologies for post-fault operation are chosen and studied, and suitable control strategies are proposed. Once again, various control strategies are considered for each converter topology, and their performance is evaluated and compared by means of simulations and experiments. Finally, three fully-integrated fault-tolerant PMSG drives are suggested by taking into consideration their design, control system and real-time response.