Abstract
This thesis presents the development and operation control of a DC microgrid with photovoltaic (PV) cell and wind permanent-magnet synchronous generator (PMSG). A single-phase three-wire (1P3W) 60Hz 220V/110V load inverter is equipped for making its operation performance test. The robust controls for the developed bidirectional 1P3W inverter are proposed to yield good AC output voltage waveforms and good line drawn current in switch mode rectifier (SMR) operation mode. The PV source is interfaced to the common DC bus of microgrid via two interleaving boost DC/DC converters. Smaller PWM ripples and rating enlargement of the established converter are preserved thanks to the interleaving approach. The maximum power point tracking (MPPT) control is also applied to extract the solar energy as effective as possible. As to the wind PMSG, it is connected to the common DC bus through a properly designed Vienna three-phase SMR. Sinusoidal armature winding currents are obtained using only three power switches. The effects of commutation shift on the generating performance of an SPMSM are also studied experimentally. The developed microgrid is supported by an energy storage system including a Li-ion battery, a supercapacitor and a flywheel. Each storage device is interfaced to the common DC bus by an one-leg bidirectional DC-DC converter. Good charging and discharging characteristics of each device are achieved through proper schematic and controller designs. And the effective use of energy storage to improve the microgrid power quality can be obtained by properly dispatching these storage devices according to their response characteristics and capacities. Moreover, the charges of these devices can be made via the plug-in a charger formed by the 1P3W inverter from mains for the occurrence of long-term renewable energy exhaustion. While the Vienna SMR is implemented employing a specific power module, all other constituted interface converters of PV source, energy storage devices and 1P3W inverter are constructed using two three-phase intelligent power modules. The digital control algorithms of all power stages are realized using digital signal processor (DSP). Some experimental results are provided to demonstrate their performances.