Research On Reconfiguration Of Three-phase Unbalanced Distribution Network With Distributed Generation

Distribution network is responsible for the distribution and supply of electric energy in the power system,which is directly connected with the user's loads.The network structure is huge and complex.The unbalanced three-phase power and asymmetric line parameters are common problems.With the increasing number of distributed generation and intelligent load connected into distribution system,the traditional distribution network is gradually transforming into active distribution network with multiple sources and uncertainties,which seriously affects the safe and efficient operation of distribution network and the reliability of power supply.Therefore,it is necessary to start with the optimal operation and regulation of active distribution network,and to study the optimal operation of active distribution network and the restoration of power supply after fault.Firstly,the background and significance of distribution network reconfiguration technology are analyzed,and the current research situation is analyzed from two perspectives of distribution network optimal reconfiguration and fault recovery reconfiguration.The results and problems of existing research are summarized.Based on this,the research framework of this paper is constructed.Secondly,the purpose of the study is to build the distribution network topology and reconfiguration optimization model,develop the solution algorithm and verify the validity of the model.Based on the linear static optimal reconfiguration model of distribution network,a mathematical model for optimal reconfiguration of active distribution network is established.Considering that the objective function and constraints of the reconfiguration model contain non-linear terms,it is a non-convex model,and the optimal equidistant linear approximation method is used to relax the model into a linear programming model.Comparing with artificial intelligence reconstruction algorithm,it proves the effectiveness of the proposed linear optimization reconstruction model of distribution network,and compares the optimization performance and solution efficiency of different reconstruction models by using different scale examples.Then,the box interval model of uncertain set Considering Uncertain budget is built for the uncertain factors in distribution network with distributed generation.Based on the linear optimal reconfiguration model of distribution network,a dynamic optimal reconfiguration model of Distribution Network Considering Uncertain injection power during the reconfiguration period is established.The original optimization model is transformed into a two-level robust optimization model.The model is divided into two models,the main problem and the sub-problem,by using column constraint production algorithm with high computational efficiency and solving performance.The effective solution of the original robust optimization problem is achieved through interactive iteration,thus the switching action strategy of distribution network is obtained.The effectiveness of the proposed robust optimal reconfiguration model and decomposition algorithm is proved by 33-node standard system.Finally,based on the Distflow branch power flow and uncertain power model,the influence of the incorporation of distributed generators into distribution network on the restoration of power supply after faults is expounded,and a two-tier robust fault recovery reconfiguration strategy considering distributed generators is established to coordinate the recovery process of islands and residual networks after faults.Active distribution is studied by adding virtual root nodes and virtual branches.The method of islanding synchronization partitioning in power network is proposed,and the islanding synchronization partitioning model considering reserve capacity and frequency offset is built.Based on the robust reconfiguration mathematical model,the robust restoration model of distribution network residual network is established.Finally,through the simulation of a standard example,it is proved that this chapter's fault recovery strategy can achieve as much load recovery as possible under power fluctuation and enhance the active distribution network.The ability of load to quickly restore power supply.