Operational strategy for multi-converter based variable speed wind generator during network fault S. M. Muyeen 1 * ,y and J. Tamura 2 1 Department of Electrical Engineering, The Petroleum Institute, P.O. Box 2533, Abu Dhabi, U.A.E 2 Kitami Institute of Technology, 165 Koen-Cho, Kitami, Hokkaido 090-8507, Japan SUMMARY This paper proposes novel multiconverter operation and control scheme for variable speed wind energy conversion system to withstand against grid fault. The full or partial rating frequency converters (FCs), in general, are widely used in variable speed wind turbine (VSWT) driven wind generators. Among the variable speed wind generators, permanent magnet synchronous generator (PMSG), which uses a full rating FC for grid interfacing, is drawing much attention nowadays due to its salient features. However, considering the factors such as higher-reliability, higher efficiency, and lower harmonics, the multiconverter based topology might be preferable instead of using a full rating FC. This paper proposes a coordinated control scheme for multiple parallel-connected FC units integrated with VSWT driving PMSG to augments the transient performance during a network disturbance. Multimode operation (inverter and rectifier) of the individual FC unit is another salient feature of this study. Copyright # 2010 John Wiley & Sons, Ltd. key words: frequency converter; multiconverter; permanent magnet synchronous generator (PMSG); transient stability; variable speed wind turbine (VSWT) 1. INTRODUCTION Over the last decade the renewable energy sources such as solar, wind, biomass, wave, etc. have been investigated considerably from the viewpoint of increasing demand of electricity, depletion of fossil fuel, and global warming. Among those renewable energy sources wind energy stands as true alternatives to conventional technologies for electricity generation. Wind energy also has the clean energy feature which is important considering the fact of global warming. In 2008, 27 GW wind power has been installed all over the world, bringing world-wide installed capacity to 120.8 GW. This is an increase of 36% compared with the 2007 market, and represents an overall increase in the global installed capacity of about 28.8% [1]. From these statistics it can be predicted that huge number of wind turbine generator units are going to be connected to the existing power system. Therefore, the efficiency, stability, and reliability of the wind energy conversion system are the major concerns from the viewpoint of transmission system operators (TSOs), especially when bulk amount of electrical power is expected from wind farm. This study focuses on the stability and reliability issues of particular wind turbine generator system (WTGS) in which the generator is decoupled from the grid using a full-scale frequency converter (FC). Transient stability analysis for fixed speed wind generators has been reported in many literatures [2– 4]. But variable speed WTGS has recently become more popular than the fixed speed WTGS. A few types of variable speed wind turbine (VSWT) generator systems are commercially available, nowadays. Among those technologies, the direct drive concept is becoming very popular these days. *Correspondence to: S. M. Muyeen, Department of Electrical Engineering, The Petroleum Institute, P.O. Box 2533, Abu Dhabi, U.A.E. y E-mail: muyeen0809@yahoo.com This is the author's version of an article published in EUROPEAN TRANSACTIONS ON ELECTRICAL POWER. Changes were made to this version by the publisher prior to publication. DOI: 10.1002/etep.539