Transient Modeling And Simulation Of The Lv Micro-grid With Multiple Distributed Energy Sources And Energy Storage Elements

At present, the most common distributed generation (DG) technologies include wind power, solar photovoltaic generation, fuel cell generation and micro-gas turbine, etc. Multiple distributed energy sources (DERs) can be integrated into the large grid to supply power as complementary sources. Moreover, these small, modular distributed generation technologies interconnected to the distribution system have the potential to form a new type of power system, the Micro-grid. Micro-grid is an integration of distributed energy sources, energy storage elements, various loads and kinds of controllers. This new grid, which can efficiently take use of multiple energy sources and possess high flexibility, is developing fast as one of the strategic goals of the future power system.Transient modeling and simulation is an efficient method to analyze dynamic characteristics of the micro-grid. Transient modeling of the micro-grid requires detailed modeling of all the DERs, energy storage elements and controllers, and it also needs precisely simulate switching actions of all the power electronic devices. Transient simulation of the micro-grid is mainly used to analyze dynamic behaviors occurred in the grid, such as fault, power quality analysis, controls for different operations, etc. Since transient simulation targets on fast transient in the system, it must use detailed element models and small simulation step to obtain accurate simulation results. Moreover, distributed energy sources include both still ones (such as PV cells, fuel cells) and circumvolving ones (such as micro-turbines, wind-turbines), and plenty of power electronic devices and multi-stage energy conversion also exist in the micro-grids, so transient modeling and simulation of the micro-grid is definitely a quite complex work.In the paper, two simulation programs, MATLAB/Simulink and EMTDC/PSCAD, are used to build detailed transient models for the grid-connected photovoltaic generation system, fuel cell generation system, micro-gas turbine generation system and battery energy storage system. In addition, different cases are simulated to test these transient models for each distributed generation system. What is more, these DG units are interconnected into the EU benchmark low-voltage distribution system to form a LV micro-grid with multiple DERs and energy storage elements. Finally, steady-state operation and short-circuit fault cases are simulated on this LV micro-grid. All simulation results have verified both the feasibility of the transient models and the validity of the control methods.