Optimal Energy Dispatch Of Grid-connected Microgrid

In order to give full play to the advantages of distributed generation technology and implement load demand side management and maximize the use of renewable energy, microgrid through the integration of a variety of distributed generation, it has important significance to guarantee the reliability and flexibility of power supply and improve the quality of power supply and reduce environmental pollution and improve energy utilization efficiency, etc. At present, the microgrid energy optimal dispatch is the key technology in the research of the microgrid research field, however, there are still many problems need to be solved. On the one hand, in order to meet the requirements of the microgrid system, such as security, reliability, economy, etc, the method and strategy of the microgrid energy optimal dispatch is needed to study, which is the emphasis and difficulty in the research of the microgrid research field, on the other hand, it has very important practical significance to reduce the randomness and volatility in the renewable power generation through the microgrid energy optimal dispatch technology with the increasing of the penetration of renewable generation.Firstly, this article summarizes the overseas and domestic research status of the microgrid energy optimal dispatch based on the consideration of economy, environmental protection, reliability, security, etc, then detailed analyze the basic concept of distributed generation technology, the economic operation strategies of the microgrid and the optimal operation characteristics of the microgrid. Given the features of each distributed power in the microgrid and the purpose of maximizing the advantages of the techiques of distributed generation which are shown in the aspects of economy, environment and energy, after meeting the constraints from the system, this paper proposes an economic dispatching model of the multi-objective microgrid which is an integrated consideration of the running costs, voltage bias and the capability of cutting the summit and filling the peak valley of the microgrid.Secondly, the paper proposed an optimal load distribution method in microgrid. The model of economic dispatch of microgrid was set up to illuminate the intermittent uncertainty of power generation output, load and the system equipment which will bring the influence to microgrid, In this model, the indexes of the voltage safety margin and the load loss rate were provided to satisfy the security and reliability of power system under the condition of system constraint. This paper analyses the microgrid’s economy relationship between safe and reliable constraint indexes under different confidence level, which can offer useful guidance to the secure, reliable and economical operation of the microgrid. This article analyses the microgrid economy with different confidence level of safe and reliable constraint relations through an actual example, and it has a certain guiding role to the micro grid safe, reliable, economic operation.Thirdly, in order to reduce the randomness and volatility of renewable generation, and to realize the microgrid’s safe, reliable and economic operation, this paper proposes the double-layers of microgrid energy optimal dispatch model considering the coordination of economy and reliability under the condition of system constraint. The model of economic dispatch of microgrid is set up to illuminate the intermittent uncertainty of power generation output, load and the system equipment which will bring the influence to microgrid, In this model, the schedule layer obtains spinning reserve and operation plans to satisfy the indexes of reliability and the indexes of resources of power system, while the dispatch layer provides the optimal allocation policy of spinning reserve. Using double-layers of microgrid energy optimal dispatch model to deal with the indeterminacy of uncontrollable units, and to realize the requirements of power reliability as well as the rational use of systematic resources. The actual example analyses the relationship between the economy and the security and reliability constraint indexes under the different confidence level of microgrid, which proves the validity of the proposed model and the effectiveness of the proposed method. The simulation results showed that the double-layer of microgrid energy coordinated dispatch more economical than the traditional dispatch patterns, and have a better effect to the network security and reliable operation.With the development of microgrid technology, the study about method and strategy of microgrid optimal dispatch will become more and more popular. In the process of development, innovation and applications there will be many new problems, in order to solve the control problem in scheduling of microgrid more reasonably, effectively and specifically, we need a deeper and further research.