Energy Management And Control System Improvement For Microgrid

?Nowadays, in international society, environmental regulatory requirements are becoming increasingly stringent and the energy reserve of chemical fuel is rapidly dwindling. Thus the applications of green energy sources have becoming the focus of world's attention. In China, large area of ice storms and frequent earthquakes causes great losses such as the damage of power supply line in these years.In the circumstance, the power supply method which combines traditional grid and distributed generation (DG) has been considered as an effective way to reduce investment, lower energy consumption and improve the reliability and flexibility of power system. DG enjoys many advantages such as improved power quality and reliability of power supply, optimized resource allocation, saved operational cost of transmission and distribution, energy conservation and environment protection, etc. On the other hand, DG also suffered from a number of disadvantages such as low generation power, high cost of stand-alone access, difficulties of running control, etc.The concept of microgrid is created to overcome the shortcomings of DG and the conflicts between traditional grid and DG. Microgrid itself is a combination of DGs and energy storage units. It can achieved the energy storage and conversion within the system, which results an improved rubustness and emergency solving ability. Microgrid can also provide power of satisfying power quality to the customers.Microgrid runs in two modes: grid-connected mode and stand-alone mode. The thesis studied the controlling goals of microgrid running in these two modes respectively, and studied the joint control and management of DG. This paper carried out the following work:1) To conclude the external characteristics of microgrid according to the control strategies for single DG(photovoltaic cells, batteries, fuel cells, wind turbines, micro turbines). And then modify and approximate on this basis and processing them as three types of corresponding nodes in flow calculation.2) According to the reference system provided by CIGRE C6.04.02 group, to establish a 8-node-microgrid system. The line parameters and loads' and power resources' capacities are all referred to the relevant recognized documents.3) To program in Matlab, basing on the open source codes in Matpower toolkit, modifying with niche immune optimization algorithm. Its objective function is powerflow calculation and its control variables are status of DGs and search the optimal solution under one certain goal.4) To calculate and analyze a variety of power management strategies under two running modes of microgrid, aiming at minimum network loss and optimal power quality. 5)To take an instance of grid which adapted IEEE30 system, analyzing the influence on main grid when microgrid exchanges energy with main grid, working out the penetration limit. To take Dongying grid as example, analyzing the impact of wind power into main grid.