Improved dynamic modelling of DFIG driven wind turbine with algorithm for optimal sharing of reactive power between converters

In this paper, dynamic modelling of Doubly Fed Induction Generator (DFIG) considering the stator-rotor circuit electromotive force model is developed to compensate for the voltage drop and ensure ease in the calculation. Converter control of DFIG is designed to share reactive power at lower than rated wind speeds, effectively reducing rotor winding copper losses. Loss reduction and maximum power control are achieved by adequately controlling active and reactive components of rotor currents through the Rotor Side Converter (RSC) control for an efficient system. Control strategies for decreasing DFIG losses are described in this article. The stator power factor is offered to determine DFIG's reactive power support by rotor and grid side converters. At any wind speed, the reactive power-sharing ratio for converters is estimated to reduce machine copper losses. The optimum source of the reactive power depends on the relative loss consideration in the machine. However, this reactive power-sharing approach enhances system efficiency. To test the suggested formulation and examine the grid-interactive DFIG fed wind turbine performance for the controlling techniques, a Matlab/Simulink model of a 2.5 MW wind turbine is developed.