Modeling and Control of a Variable-Speed Constant-Frequency Synchronous Generator With Brushless Exciter

Abstract

This paper presents the modeling, control, and implementation of a novel variable-speed constant-frequency power generation system for renewable and distributed energy applications. The generation system consists of a wound-rotor generator, a brushless exciter and a low-rating controlled power converter. The main generator is a doubly fed induction machine which is operated as a synchronous generator. The advantages of the proposed system are reduced harmonic injection to power grid, wide speed operation range covering both subsynchronous and super-synchronous speeds, self var support, and increased reliability. It can be directly applied to wind power generators, small-scale hydroelectric generators, stand-alone diesel and gasoline generators, and aerospace and naval power generation systems where a variable speed turbine/engine is employed. An equivalent circuit model of a doubly fed generator was developed incorporating stator and rotor iron losses. Then the control of a standalone generation system is developed based on the mathematical model. Detailed implementation procedure is given. An experimental system and its control were implemented using an embedded real-time digital signal processor. Measurements of the experimental system validated the system design and readiness for prototyping in a relatively large power range.

DFIG control: A fuzzy approach

“…The rest of paper is organized as follows: After the wind energy conversion system modeling, we present the fuzzy controller design. Before concluding, several simulation results are presented to confirm our objectives (Mi et al, 2004;Agarwal et al, 2009).…”

Optimal Design and Experimental Verification of Wound Rotor Synchronous Machine Using Subharmonic Excitation for Brushless Operation

“…Several brushless excitation techniques for WRSMs have been proposed [1][2][3]. In large synchronous machines such as steam or water turbine generators, an additional brushless exciter is utilized for rotor field excitation [4,5]. However, in small and medium sized electrical machines for electric or hybrid vehicles and other industry applications, it is not suitable to use a separate brushless exciter due to limitation of volume and cost.…”

A novel method for grid integration of synchronous generator based wind energy generation system

“…These power electronic converters cause harmonic distortion and thereby deteriorate the quality of power supplied. Further, they require suitable compensation in order to meet the standards for harmonic pollution which further increases the cost and complexity of the system [4] - [5].…”