Abstract
This dissertation is aimed at the development and operation controls of a DC micro-grid powered by wind permanent-magnet synchronous generator (PMSG) and DC source with hybrid energy storage devices. The DC sources are interfaced to the common DC bus via an interleaved DC/DC boost converter. As to the wind PMSG, after exploring the derated characteristics of PMSG systems with various AC/DC converters, a three-phase Vienna switch-mode rectifier (SMR) is developed as its interface to establish the common DC bus voltage of DC micro-grid. Its developed power is improved by proper commutation tuning and robust controls. The possible harvested DC or AC sources can be interfaced to the DC micro-grid via the embedded circuit components of Vienna SMR. Since the generating powers from various sources in a micro-grid are unpredictable and fluctuated, energy storage buffer is required to improve its power supplying quality. In the developed micro-grid, the battery/flywheel/super-capacitor hybrid energy storage system with bidirectional DC/DC interface converters is developed. And the droop control approach with adaptive predictive current control is proposed to yield good energy storage support control characteristics. Moreover, a chopped resistive dump load is equipped to regulate the energy balance when system energy surplus occurs. In test load arrangement, a single-phase three-wire (1P3W) inverter is established to yield 60Hz 220V/110V AC voltages for powering the home appliances. Good sinusoidal output voltage waveforms and dynamic responses due to load and DC-bus voltage changes are obtained by the proposed robust control schemes. When the renewable energy is surplus or insufficient, the microgrid-to-grid (M2G)/grid-to-microgrid (G2M) bidirectional operations can be also conducted by the established 1P3W inverter. Moreover, the bidirectional inter-connected operations between the developed micro-grid and the electric vehicle (M2V/V2M) can also be applicable. In addition, various motor drives, lighting devices and DC converter fed loads can be directly powered from the DC bus of the established micro-grid.