Nonlinear Modeling and Simulation of a Four-phase Switched Reluctance Generator for Wind Energy Applications

Abstract

Abstrac t—Thesubject of this paper is a modeling method of switched reluctance generator (SRG) based on the nonlinear inductance model and electromagnetic field finite element analysis (FEA) to be used in wind energy applications. SRG and its behavior, modeling and Simulations results are presented. It was analyzed the characteristics of the SRG under different conditions. The nonlinear inductance model allows us to develop a control strategy that gives high performance controller with a closed loop was designed on PI controller. I. INTRODUCT ION The rapid depletion of fossil fuels has necessitated the need for the utilization of non-conventional energy sources. Among these renewable energies widely used around the world in the last years, wind energy conversion system seems to be very interesting, it is clean energy source suitable for rural areas and the stand alone wind energy conversion system in rural areas must be characterized by economic and maintenance free operation. Doubly fed induction generator (DFIG) suffers from limited rotor converter rating and has problems with over currents during voltage dips and the multistage gearbox that the DFIG must incorporate is unreliable and expensive. The direct coupled variable speed generators for these systems obviate the need for gear box which is the most unreliable and maintenance intensive component in the system. Permanent Magnet Synchronous Generator or Field Wound Synchronous Generator in standalone wind energy conversion systems eliminate the unreliability associated with gear box drive trains through direct coupled variable speed operation and even though permanent magnet machines will have a better torque density than the field wound version, the presence of permanent magnets will make assembly more difficult (1). In the Field Wound Synchronous Generator, the brushes required to excite the field winding demand maintenance at regular intervals. The variable speed direct drive synchronous generator shortfalls fr om cost, size, weight, energy yield and requirement of a converter. Although Permanent magnet generators exhibit low losses, lower weight, better torque density and perhaps low cost with the disadvantage that the excitation cannot be controlled while axial flux permanent magnet generators are heavier and more expensive than radial flux counterparts. To overcome the beyond mentioned obstacles Switched Reluctance Generator (SRG) is being considered as the generator of choice in standalone wind energy conversion