Maximum Active and Reactive Power Capability of a Matrix Converter-Fed DFIG-Based Wind Energy Conversion System

Matrix converter (MC)-fed doubly fed induction generators (DFIGs) as wind energy converters are attracting increasing research interest due to their compact size and longer life span. This paper presents the active-reactive power diagrams, similar to the operational chart of a synchronous generator, for an MC-fed DFIG-based wind energy conversion system (WECS) at different wind speeds. These diagrams are useful for estimating the available reactive power support to the grid from the WECS. To derive these diagrams an algorithm is developed to calculate the optimum reactive power share of the DFIG stator and the MC which maximizes the active power injected to the grid at a given grid power factor at each wind speed within the design limits of the system components. A new steady-state model of the MC, as seen from its input side, is also developed to accurately predict the maximum possible reactive power support by the MC under different operating conditions. Predictions from this model and the optimal reactive power sharing algorithm are experimentally validated on a laboratory prototype. Finally, the active-reactive power diagrams of an MC-fed grid-connected DFIG-based WECS are derived at different wind speeds.