An Economic Operation Model For Isolated Microgrid Based On Distributed Algorithm

Microgrid can operate under grid-connected and islanded mode. When fault in main grid occurs, Microgrid will turn into islanded mode and provide power energy to loads continuously.In order to minimize the operation costs and to guarantee the reliability of power supply,the optimal dispatching for distributed generation is a necessity. In the study of microgrid optimal operation, distributed algorithm is widely used because of its simple calculation, low requirements for communication network (only local information is needed) and fast convergence speed.In order to effectively solve the energy management problem during the operation process under islanded mode, this thesis has carried out following studies regarding to the islanded mode of Microgrid.First of all, this thesis introduces current situation of the development of Microgrid, discusses the significance of Microgrid economic operation and summarizes the status of the existing algorithms applied in Microgrid economic dispatching problem. Aiming at shortcomings of the existing centralized control algorithm, the concept of distributed algorithm is introduced in this thesis, and the research status of distributed algorithm and it application in Micro-grid is summarized.Secondly, according to the characteristics of islanded Microgrid, taking the lowest economic cost and the highest power supply reliability as optimization targets, economy evaluation indexes are established. In order to solve this model, a consensus-based optimization algorithm that adopts the method of bisection is introduced. The principle of the algorithm, the design framework and the process of the distributed bisection algorithm are further illustrated, numerical simulations are given to verify the performance of the algorithm.Finally, aiming at improving the proposed economic dispatching model of Microgrid operating under islanded mode, an objective function considering user interests is proposed in this thesis, and a fully distributed algorithm based on multi-agent framework (MAS) is presented, which could be used in the dispatching of Microgrid under islanded mode. Principle and procedure of the proposed distributed algorithm is described and followed by a simulation. Number of iterations in simulation shows that the proposed algorithm is with good convergence properties. Also, the proposed algorithm is further validated by other reliable means, such as GAMS (which is successfully applied in many fields), and Particle Swarm Optimization algorithm. Results show that the fully distributed algorithm proposed in this thesis has the advantages of short calculation time and fast convergence speed.