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An isolated wind power generation scheme using slip ring induction machine (SRIM) is proposed. The proposed scheme maintains constant load voltage and frequency irrespective of the wind speed or load variation. The power circuit consists of two back-to-back connected inverters with a common dc link, where one inverter is directly connected to the rotor side of SRIM and the other inverter is connected to the stator side of the SRIM through LC filter. Developing a negative sequence compensation method to ensure that, even under the presence of unbalanced load, the generator experiences almost balanced three-phase current and most of the unbalanced current is directed through the stator side converter is the focus here. The SRIM controller varies the speed of the generator with variation in the wind speed to extract maximum power. The difference of the generated power and the load power is either stored in or extracted from a battery bank, which is interfaced to the common dc link through a multiphase bidirectional fly-back dc–dc converter. The SRIM control scheme, maximum power point extraction algorithm and the fly-back converter topology are incorporated from available literature. The proposed scheme is both simulated and experimentally verified. [ABSTRACT FROM AUTHOR]

A rotor position estimation scheme for stator flux-oriented speed sensorless control of slip ring induction machine (SRIM) is presented in this paper. Position of the rotor is estimated by integrating the rotor back-electromotive force. The problem of DC drift during integration is eliminated using an error-decaying mechanism in the estimator. This estimation scheme reduces the propagation of noise in the sensed current to the estimated rotor side unit vectors. This scheme also eliminates the need for differentiating the unit vectors for estimating slip frequency. The proposed scheme is simulated and experimentally verified. [ABSTRACT FROM AUTHOR]