Research On DC Micro-Grid Simulation System

As global warming and energy depletion problems increasingly cause the attention of people, effective use of renewable energy to replace fossil material and reduce greenhouse gas emissions has become a global problem. Dc micro power grid as a new concept developed in the field of power system in recent years provides the solution to solve the problem of the use of renewable energy. In order to realize the interconnection of dc micro renewable energy with power grid, providing reliable power supply for end users, the simulation system of dc micro power grid were studied in this paper as follows:Firstly, this article puts forward the voltage balancer suitable for dc micro power grid, analyzes the principle of voltage balance according to the main circuit topology structure, and uses state space average method for mathematical modeling of circuitThe simulation results show that the voltage balance can better realize the stability of the dc output voltage.Secondly, the research on the bidirectional dc converter applied in dc micro-grid is expanded. Different working modes of the converter are analyzed in detail, the dc converter applicable to micro power grid is formed through the symmetry extension of traditional bidirectional DC/DC converter structure. This paper adopts double loop control method of the limiting implementation achieving the free flow of energy on both sides. The simulation results show that the proposed bidirectional DC/DC converter can realize exchange of power effectively and dc bus voltage stability to the reference at the same time.Thirdly, super capacitors is used for DC micro-grid energy storage device to adjust the energy of the system, fuel cell as a distributed power supply. Both are connected to DC micro power grid according to the principle and function of super capacitor and the fuel cell through micro interface bidirectional DC/DC converter.Finally, power flow problems of the whole dc micro grid system are studied considering the micro grid system under various operation modes during load change and the remove and interconnection of power supply. Dc micro grid simulation results show that the simulation system can realize fuel cell interconnection, super capacitor energy storage device can effectively complete energy flow of the grid, maintain normal power supply ensuring the stable operation of power grid under the load and micro power access to and removal from the system.