Study Of Operation Optimization And Energy Management For Microgrids

In recent years, in order to make full use of distributed energy resources, many attentions are paid to integration and operation control of microgrid, which is also an important part of smart grid. As a new energy supply and network management technology, microgrid could allow renewable and clean resources to penetrate into a utility. At the same time, it could achieve demand-side management and maximum utilization of existing energy. It is flexible and dispatchable, namely it could operate in grid-connected or stand-alone mode and could switch between the two modes seamlessly. This paper focuses on issues related to the operation optimization and energy management of microgrid.First of all, this paper gives an in-depth study of development and research about microgrid at home and abroad. From the viewpoint of technical connotation, the present research situation of key technologies for the microgrid is reviewed. These technologies include such as modeling and simulation research in component-level and system-level, issues related to operation control and energy management, microgrid environmental and economic evaluation.Secondly, in contrast to traditional power system, two kinds of current structure and three types of operational control methods for microgrid during the stand-alone mode are summarized and described in detail. The characteristics and application occasions of those methods are compared. Besides, based on existing achievements of energy management, the author sums up several aspects, which are about new generation of energy management for microgrid and should be paid more attention, taking into account the impacts, similarities and differences between traditional energy generation systems and distributed generation systems.Thirdly, this paper selects some distributed generation technologies as objects, which are relatively mature and have better prospects. And their relevant features are studied and analysed. Then, based on steady state characteristics of these distributed generators, this paper proposes an optimization and dispatch model of microgrids in centralized control, objective functions with minimizing the cost of operation or depreciation and maximizing environmental or comprehensive benefit, and three interactive operational control strategies. The problem is figured out by improved genetic algorithm adopting tournament selection, single-point crossover and Gaussian mutation. In addition, the model is validated by studying a specified case with different factors.Then, energy storage technologies have been widespread concerned, because microgrid that includes intermittent renewable energy power generations could withstand relatively weak disturbances. The paper gives a review on energy storage technologies. The technical data and characteristics of NAS battery, lithium-ion batteries and vanadium redox flow battery are described in detail. NAS battery is then selected as the object. It is commercial and suitable in power system application. The battery also has various performances. Considering the operational modes and impact of battery, an economic operation optimization model for microgrids including NAS battery has been proposed. Furthermore, the model is validated by studying a specified case with a variety of scenarios.Finally, framework of microgrid energy management system is researched in this part. The differences between microgrid energy management system and traditional energy management system are pointed out. A survey of microgrid energy management system is presented. These aspects are mainly composed of development issues, key functions, design objectives and architecture about software. And, withal, the application of economic operation optimization for microgrids is elaborated.