An Analytical Approach to Maximum Power Tracking and Loss Minimization of a Doubly Fed Induction Generator Considering Core Loss

Abstract

To get maximum output power from a doubly fed induction generator (DFIG), it is essential to extract maximum mechanical power from the wind turbine and to minimize generator losses. The goal of maximum power tracking and minimum loss is usually achieved through vector control of rotor current. In other words, the d-axis and q-axis rotor currents I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dr</sub> and I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">qr</sub> must be properly controlled as wind speed changes with time. In this paper, an analytical approach is developed to determine proper rotor current commands I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dr</sub> * and I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">qr</sub> * which give maximum mechanical power and minimum loss based on the measured generator speed. The proposed analytical approach is more efficient than the exhaustive search approach proposed in a previous study and is, therefore, more suitable for real-time performance improvements. In addition, core loss component, which was usually neglected in previous studies, is included in the DFIG model in order to have more accurate results. The effectiveness of the derived analytical formulas is demonstrated by an example.