Dynamic performance analysis and improvements of a current source converter based PMSM wind energy system

In a current source converter (CSC) based wind energy system, the dc link current plays an important role in determining the system dynamic performance. This paper proposes two control strategies that can be used to improve the dynamic performance of the dc link current in a CSC wind energy system using permanent magnet synchronous machine (PMSM). State space equations and small-signal models of the system are developed, based on which the system dynamic behavior is investigated. It is demonstrated that the dc current of the proposed wind energy system can be controlled by either the rectifier or the inverter, but the latter provides much better dynamic performance and is therefore recommended for practical implementation. The system performance can be further enhanced by introducing a damping control to suppress possible LC resonances caused by the generator- and grid-side LC filters. Computer simulation and experimental results are provided to verify the theoretical analysis.