A comparative power quality study of DFIG and PMSG renewable energy conversion systems

Abstract

Wind Energy Conversion Systems (WECS) are faced with escalating demand for power quality and total harmonic distortion (THD) control. With the advances in power electronics technology, the rapid growth of variable speed WECS is now witnessed. However, the power quality still remains an important issue to be addressed thoroughly by researchers. This project presents a comparative study on grid connected WECS (DFIG and PMSG) in terms of output powers (P&Q), Voltages and currents, THD and dynamic responses following a fault (duration=90ms) on the machine side bus (B575). Both systems are connected to power grid through unconventional back to back converters. The DFIG is modeled using the direct-quadrature rotating reference frame circuit along with the aligned stator flux, and the field-oriented control approach is applied for independent control of the active and reactive power and the DC-link voltage at the grid side. Improvement of the controllers of the DFIG from the rotor side and the stator (grid) side converters are done to enhance the dynamic performance. The comparison also aims to present in a thorough and coherent way the aspects of power quality in terms of reduction in Total Harmonic Distortion (THD) during the fault period. All the simulations are made in Matlab/Simulink.