Topology Identification And Parameter Calculation Of Power Supply Network Based On Smart Meter Data

With the rapid development of modern power system,the scale of power grid is expanding day by day,and the operation mode is more flexible,which puts forward higher requirements for the operation and management of power distribution network.As the last link of the distribution network,the low-voltage power supply network directly supplies power to customers,which plays an important role in ensuring the reliability of power supply.In order to meet the safety,reliability and economy of the distribution network and improve the lean management level of the distribution network,it is necessary to conduct real-time monitoring and analysis of the running state of the low-voltage power supply network.The realization of state estimation,power flow calculation,fault location and other functions depends on accurate topology structure and line parameters of low-voltage power supply network.In recent years,Advanced Metering Infrastructure(AMI)has developed rapidly.As the terminal device of AMI,intelligent meters are responsible for the collection and upload of electricity information,which has generated massive measurement data.These data not only contain the electricity consumption information of each node at each moment,but also contain the topology information of the power supply network.There is a specific mathematical relationship between the electricity consumption information and the network topology.Therefore,the topology structure of the power supply network can be obtained by inversely derive the connection relationship between the nodes according to the measurement data of the smart meter,and then the line parameters can be obtained.At present,the researches on power supply network topology identification mainly focus on the regular topology structure,that is,the power supply network with single node type,clear hierarchical relationship and radial distribution.However,there are many kinds of low-voltage power supply networks in our country that has complex structure.Many low-voltage power supply networks have unclear hierarchy and irregular user distribution.Therefore,a more general method is needed for topology identification and line parameter recognition.To solve the above problems,this paper mainly carried out the following work:Firstly,the general structure of low-voltage power supply network is established.Considering the complex situation that there may be users connected on the branch lines between adjacent branch nodes,a representative topology model of complex power supply network is established.The electricity meters are divided into two categories:branch meters and user meters,and the overall topology recognition strategy is proposed,which is to identify the connection relation of branch nodes first,and then identify the location of user nodes.Secondly,according to the overall topology recognition strategy,a topology recognition method of low-voltage power supply network based on wavelet transform feature extraction and 0-1 integer quadratic programming is proposed.This method analyzes the power sequence variation characteristics of the branch nodes,takes the power mutation as the feature,uses the wavelet transform to extract the mutation characteristics,and identifies the connection relation of the branch nodes by comparing the similarity of the feature power sequence.After the connection relation of the branch nodes is obtained,the power of each branch segment is calculated,and the mathematical model of 0-1 integer quadratic programming is established by using the equal relation between the power of the segment and the sum of the power of the users connected to the segment,and the position of the user nodes is obtained by solving the mathematical model.Then,the method of testing hypothesis is used to check and correct the topology identification results,and an accurate and complete network topology is obtained.Field data are used for example analysis of the above method,and the results show that the method has high accuracy and reliability.Finally,on the basis of the topology is obtained,a line parameter recognition method based on multivariate nonlinear optimization is proposed.Based on the voltage drop equation of the user line,the multivariate nonlinear optimization mathematical model is established,and the Levenberg-Marquarat method is used to solve the optimization model to get the parameter estimation of the user line.Based on the parameter estimation method of user line,an iterative method for estimating parameters of branch line with hidden nodes is proposed,and the parameter recognition of all lines is completed.A simulation model was built on the PSCAD platform,and the meter measurement data obtained from the simulation was used for example analysis.The results show that the method in this paper has high accuracy.