Study On Cluster Partition Method Of Distributed Generation Considering Flexibility

In order to achieve large-scale renewable energy coordinate with the grid friendly and maximize the demand for grid-connected absorption functions,the cluster approach,which is used for planning construction and scheduling control,has become a forward-looking solution for the distribution network.Under the background of complex multi-element fusion distribution network,the high volatility and uncertainty of distributed renewable energy output,such as wind power and photovoltaic power and so on,have deepened the complexity of the operation characteristics of the cluster on a short time scale and hindered the process of realizing the friendly grid-connection characteristics of the distributed generation cluster.Therefore,in this paper,the concept of flexibility is introduced into cluster partitioning,and various schedulable resources are integrated into a unified framework of analysis and optimization in distributed generation clusters,so as to study the cluster division method of its short time scale and the regulation characteristics of flexible resources within the cluster.According to the requirements of different research scenarios,we propose a set of indicators to reflect the flexibility of cluster,and establish a cluster partition model and method to consider the flexibility.Then the results of partition are further studied.The specific work contents of this paper are as follows:Firstly,this paper summarizes the existing cluster division theory and the flexible supply and demand relationship.From the perspective of cluster division,the principle and basis of cluster division are explained,and the existing indicators and methods of cluster division are summarized in general.According to the research of four aspects of flexibility,we give the analysis of narrow and broad flexibility demand characteristics,and explore the supply characteristics of source-load-storage multiple flexibility equipment.The above theoretical analysis lays a solid foundation for the following research on the method of distributed generation cluster division considering the flexibility.Secondly,in the deterministic background of the large-scale distributed renewable energy access,combined with the research focus of this paper,a distributed generation cluster division method for distribution network considering flexibility is proposed.The concept of cluster flexibility balance is proposed based on the definition of cluster flexibility.In order to reflect the flexible supply and demand relationship of the cluster,the flexible supply and demand balance index and the flexible balance time index are proposed.A distributed generation cluster partition model is established,which combines the flexibility and structure of the comprehensive cluster,then the genetic algorithm of adjacency matrix coding is used to solve the problem.An example based on the actual power distribution system shows that the proposed method can improve the flexibility of cluster operation.Finally,this paper further improves and proposes a more general distributed power generation cluster division method considering flexibility based on the uncertainty of the cluster's net load.According to the uncertainty problem of cluster net load,the cluster flexibility demand is analyzed with the randomness of forecast error.We propose a cluster flexibility risk index with probabilistic characteristics,and establish a cluster partition model that considers the ability to adjust flexibility resources under uncertainty.In the process of division,a coordinated control scheme for flexible resources is reasonably formulated according to the flexible demand value,and an improved genetic algorithm with adjacency matrix coding is adopted for calculation.Taking an actual county calculation example as an example,it is verified that the cluster division method considering the flexibility risk index can reduce the flexibility risk loss,and analyze the relationship between resource capacity and forecast standard deviation on the division result.