Abstract
his thesis develops a wind switched-reluctance generator (SRG) based DC micro-grid, it is equipped with a three-phase load inverter and a hybrid energy storage system consisting of a lead-acid battery and a flywheel. The established SRG is interfaced to micro-grid common DC bus via an interleaving current-fed push-pull (CFPP) DC/DC converter formed using two cells. Well regulated DC bus voltage is obtained under varying shaft driving speeds and load levels through properly treating the key issues, such as power circuit design, robust voltage and current controls, voltage command setting and commutation shift, etc. Meanwhile, lower ripples and higher reliability are possessed thanks to the interleaving operation. To make experimental evaluation for micro-grid, a three-phase load inverter is designed and implemented. The current control scheme in d-q domain with zero sequence control signal injection is adopted. Good AC output voltage waveforms and dynamic regulation characteristics under unknown and nonlinear loads are obtained. A hybrid energy storage system consisting of a flywheel and a lead-acid battery bank is established to provide energy storage support for the proposed DC micro-grid. Each storage device is interfaced to the micro-grid DC bus via a bilateral buck/boost DC/DC converter. For enhancing the SRM flywheel discharging performance, automatically adapting the voltage command, proper commutation instant setting and controller tuning are also made under generating mode. As to the battery energy storage system, good common-bus DC voltage regulation in discharging mode and good charging performance are obtained by the proper designs of its circuit and controller. Digital signal processor (DSP) is used to realize the digital controls of all constituted power stages in the developed micro-grid. The operation characteristics and control performances of the whole micro-grid are evaluated experimentally.