Control and maximum power tracking operation of hybrid excited variable speed induction generator

摘要

This paper describes a method of voltage regulation, maximum power extraction and power transfer operation in a variable speed wind-driven Induction Generator (IG) feeding DC micro grid (DCM). The IG is self-excited in a hybrid manner with fixed capacitor and a current controlled, voltage source converter (CCVSC). The control principle of CCVSC which intends to provide the VAR requirement of IG based on the power curves along with voltage regulation and maximum power tracking (MPT) with PI (proportional integral) based controllers claims the merit of the setup. The sinusoidal reference current templates of CCVSC are generated with voltage loop delivering the peak value and MPT loop delivering phase value. The frequency synchronization is effected with a 10 Phase Locked Loop (PLL). The wind power is utilized by meeting the load demand and supplying the excess power to DCM through PWM rectification of CCVSC without dissipating it through any dump load. During conditions of machine stall, the system amenably transfers power to AC loads by PWM inversion of CCVSC with fixed modulation index and frequency. When there is any fall in DCM voltage, DC voltage regulation is effected by the PWM rectification operation of CCVSC. To execute the reliable power transfer scheme, a supervisory control is employed for the automatic smooth change over in the modes of operation depending on load and wind availability. The successful operation of the system for various load/speed conditions is proved through extensive MATLAB based simulation and dSPACE 1104 controller based experimentation on a 500 W induction machine. (C) 2016 Elsevier B.V. All rights reserved.