Research On Operation Simulation Technique And Control Strategy Of Micro-Grid

Human cannot live and make production without energy. However, traditional fossil energy will gradually exhaust. The development of new energy and the utilization of renewable energy sources are the inevitable choices to solve the energy shortage. Distributed power is widely concerned by the international community because of flexibility, economy and environmental protection etc. However, the intermittent and instability of distributed power output is the mainfactors to restrict the access of large power grid. Micro-grid concept is proposed in order to solve the problem of uncontrolled distributed power and improve the utilization ratio of renewable energy. On the one hand, the micro-grid has its own energy management system, to maintain the internal energy balance, it can be regarded as a small power system; On the other hand, the micro-grid can act as a virtual source or load, to peak load shift of largepower grid. This thesis is based on the demand of development and research, and research into the micro-grid modeling, simulation and control strategy, providing theoretical support for the practical application of micro-grid. The researches are done as follows:Firstly, mathematic model of photovoltaic cell is built on the basis of the project. The photovoltaic cell simulation model and MPPT model are built by using the simulation software. Analysis of effect of temperature and light intensity on the output characteristics of photovoltaic cells is done. Battery system is designed and its model is built. Simulation of charge and discharge of battery is done to analyze its characteristics.Secondly, the control structure and principle of the master-slave control, peer control and hierarchical control are analyzed. At the same time, control (PQ control, V/f control) of micro power grid connected inverter in different control mode are analyzed in detail and theoretically derivate. A controller simulation model of V/f and PQ is constructed, and simulation is done respectively. The reliability and the effectiveness of the controller simulation model are verified.Finally, the micro-grid load balancing optimal control strategy for the operation is proposed, which includes connected grid load balancing optimal control strategy, isolated grid operation load balancing optimal control strategy, connected grid to isolated grid load balancing optimal control strategy and isolated grid to connected grid load balancing optimal control strategy. Simulation model of micro-grid including photovoltaic and energy storage is built. The grid connected operation under switching load and change the PV output, isolated network operation under switching load and change the PV output and mode switching between the two are simulated and researched.