Abstract
In recent years, multi-phase permanent magnet synchronous generators (PMSGs) have become attractive in the field of tidal current energy conversion systems (TCECS) due to their high-power density, reliability, and availability. However, external disturbances and malfunctions in power conversion chains will bring challenges to achieving stable and continuous tidal current energy harnessing. Using generalized proportional integral observers, an active fault-tolerant control (AFTC) strategy is therefore proposed for a five-phase PMSG based TCECS that is subjected to an open switch fault (OSF) in the generator side converter. This proposed AFTC strategy is applied into q-axis current control loops, which contain fault detection and compensation. The fault compensator will be smoothly activated using a sigmoid function once the OSF is detected. Finally, a small-scale power experimental platform emulating the TCECS is established in order to verify the feasibility and efficiency of the proposed FTC strategy. Experiment results show that this AFTC strategy can detect faults rapidly and effectively attenuate torque ripples in the post-fault operation mode.
Highlights
Tidal current energy has predominant advantages relative to other types of renewable energies, such as predictability, high power density, and energy continuity at almost all times, which significantly facilitates controller designs and grid connection [1]
It is composed by a five-phase permanent magnet synchronous generators (PMSGs) which is connected to a DC load through a five-leg converter
The five-phase PMSG is essentially an inertial motion system that can be indicated by a first order mechanical equation as below
Summary
Tidal current energy has predominant advantages relative to other types of renewable energies, such as predictability, high power density, and energy continuity at almost all times, which significantly facilitates controller designs and grid connection [1]. Pham et al [8] proposed a fault tolerant strategy incorporating finite control set and model predictive control methods for a five-phase PMSG based TCECS. A limitation torque control strategy according to the response of torque commands was designed by Guo et al [10] considering both short circuit and open circuit faults in a dual stator based ten-phase machine. These PFTC methodologies are able to achieve great robustness and implementability in normal and abnormal operation modes while they have obvious shortcomings, such as complicated design process of controllers, lack of supports of fault information.
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