Research On The Operation Characteristic Of Microgrid Base On Energy Storage Device

Due to the technology development and environment protection, some distributed energy resources (DER), such as micro turbines, photovoltaic, fuel cells and wind power, have entered people's field of vision. However, application of individual distributed generators can cause as many problems as it may solve, which including problem of high access costs and single DER control. The micro-grid is the most effective way to make e use of DER. Micro-grid is a small-sized grid that integrates a number of micro-sources, energy storage devices, control device and loads, which is controllable, and can either be connected to distribution grid as a special load, or disconnected from the utility to operate in island model. As a good supplementation to the traditional power supply model, micro-grid represents the new development direction of power system.When the micro-gird is operated in island mode. It should ensure the power reliability of crucial loads. In addition, different energy sources have different characteristic, which need different control methods. When connected to the utility, the micro-sources need only to supply right amount of power to keep power balance. During disturbances, the micro-grid can separate from the distribution system to isolate the local load from the distribution grid, micro-turbines immediately switch to the V/f control mode to maintain the micro-grid voltage and frequency stable, and Photovoltaic module is still running on PQ control to export stable electric power. Because of the grid-connected and independent operation is affected by the volatility of photovoltaic module, the method of using photovoltaic generation compatible with super capacitor to curb the Power fluctuations of photovoltaic power fluctuations and voltage fluctuations.At last, through simulating and analyzing the transient characteristics of the micro-Grid on the grid connected operation, the autonomous operation and ride- through mode that are conducted in terms of the load variation and 3 phases grounding fault, it shows that control strategy for DERs can sure stability of micro-grid and maintain voltage quality at required range, even during islanding transients. Therefore,the propose integrated control approach is proved to be effective and reasonable. This design offered a preferably reference for application of super capacitor in the field of the micro-grid energy storage and quality improvement of electricity power.