Research On Topology Verification And Voltage Control Strategy Of Medium And Low Voltage Distribution Network

With the development of intelligent measurement equipment,power companies can obtain real-time information of the terminal users,and the low-voltage distribution network can also use the smart meter to obtain users’ data.At the same time,because of the increasing ratio of cable,a medium and low voltage mixed distribution network is gradually formed,in which the cable and overhead are existed together.In addition,in order to improve the utilization rate of clean energy,a large number of PV system is allowed and encouraged to access to the distribution network in modern power system,and the operation of the distribution network has also been changed from passive to active.However,the power distribution and voltage quality in the distribution network are related to the safe and stable operation of the distribution network.The traditional reactive voltage control equipment cooperates with controllable DG,load,energy storage,etc.to achieve the optimal power flow distribution for the purpose of optimizing dispatch.The topology verification and voltage control strategy of integrated low and medium voltage are studied in this thesis under the context.Aiming at the problem of topological connection error in GIS of low-voltage distribution network,a topology verification algorithm based on AMI dates with K-means clustering is proposed in this thesis.Aiming at the voltage problem caused by the PV grid connection,the influence of the injected power of PV on the node voltage and power loss is studied by using the sensitivity method.Voltage sensitivity and power loss sensitivity formulas are derived.A voltage control strategy based on sensitivity analysis for an integrated medium and low voltage distribution network is proposed.Aiming at the uncertainty and fluctuation of PV output,a multi-time scale local-centralized control strategy was proposed.Centralized control uses fuzzy theory to handle power uncertainty,and adaptive weights automatically adjust the weight of the objective function.Local control adjusts the PV droop control slope according to the PV and load power,and uses the voltage sensitivity to determine the droop control parameters to optimize the power loss of the low-voltage distribution network,and solves the voltage overrun caused by power fluctuations in a short time.Through the simulation,the number of clusters K can be accurately obtained by the topology verification combined with the improved K-means clustering,and the users in the station area to be verified are clustered to identify users with incorrect topology connections.Integrated low and medium voltage control strategies based on sensitivity can convert traditional multi-objective optimization into two-stage single-objective optimization to achieve voltage control and power loss optimization,which greatly improves the optimization effect and the efficiency of control equipment.Central and local control strategies can respond to the power uncertainty effetely,and achieve coordinated optimization of medium and low voltage distribution network.