Research On Parallel Operation Of DC-DC Converters

Micro-grid is small distribution power system, made up of distributed power source, energy storage devices, energy conversion devices, load, control and protection device. It is an autonomous system which is able to achieve self-control, protection and management. It can be run with an external power grid and also can be run in isolation. It is an important part of smart grid. Micro-grid has many advantages of meeting a variety of power quality requirements and improving the reliability of power supply. It is a useful and necessary complement of Backbone grid. Micro-grid can be divided into DC and AC micro grid. The present study is mainly for AC micro gird, that is, distributed power source respectively connected to an AC network through the power electronic devices. AC micro-grid demands much difficult controls of distributed power source, it needs to consider the frequency, voltage, power and other factors separately. In addition, compared with the DC micro-grid, AC micro-grid adds inverter links which produce the additional loss and reduce energy utilization. If the distributed power sources are connected to DC micro-grid, it will reduce the requirements for control and omit the inverter part. Thus, it can get better use of distributed power source, meanwhile, power electronic devices can be saved.DC-DC converters operating in parallel circumstances present in micro-grid which consists of distributed energy resources. This thesis introduces the research on the structure of the DC-DC converters,the control strategy and the impact of the DC-DC converters to the micro-grid under the circumstances that the DC-DC converters are operating in parallel. Author did experiments on the structure of the converters and control scheme that the author proposed, the experimental results show that the structure of the converters and control scheme are feasible.