Calculation And Correlation Analysis Of 10kV Distribution Network Line Loss Based On System State Characteristics

The line loss rate of distribution network is an important economic indicator of power supply company.Aiming at the problem of low accuracy,three-phase imbalance and distributed generators access,this paper proposes a line loss calculation method based on system state characteristics,and analyzes the correlation of line loss and its influence factors,is helpful to grasp the change law of line loss,providing a new method for line loss management.The main work of this paper is as follows:(1)Aiming at the contradiction between the calculation precision of the line loss and the quantity of data transmission,this paper puts forward the thought of the system state characteristic.First of all,this paper by using millisecond sampling measurement automation terminal building every 5 minutes for current,voltage characteristic of line loss calculation.Considering the influence of current and voltage phase Angle in calculation,and considering the influence of transformer on the phase Angle,the characteristic quantity is calculated to the transformer high voltage side.The characterization current has clear physical meaning and good precision,which can reduce the pressure of data transmission while ensuring high accuracy.(2)On the basis of the two kinds of distribution network line loss calculation method is put forward.The loop current method considers the power supply and the path of each branch as a loop,and calculates the loss of each circuit through the superposition theorem to get the whole distribution network’s line loss.According to kirchhoff’s current law,the current in the distribution network is calculated from the current characteristic of the distribution network and the current of all the branches is calculated and the line loss is calculated by the current forward sweep method.In the case of distributed generators access distribution network,the definition of the current of the above two methods is carried out.The loop current method does not require the data of the distribution network topology and equipment parameters,which can quickly calculate the line loss of the whole distribution network.The current forward sweep method can grasp the distribution of line loss.The characteristics of the two methods complement each other,and the results can be verified by each other.Finally,the line loss calculation results of the actual distribution network in Dongguan show that the accuracy and practicability of the method.(3)When the sample size is small,the correlation coefficient method is proposed to analyze the line loss rate and its influencing factors.Firstly,the monthly and working days and holidays variation characteristics are analyzed,the correlation coefficients of the two are calculated to reflect the influence of influence factors on line loss.In this way,the change characteristics of line loss can be reflected fully.The various factors of line loss also can be analyzed quantitatively.When the sample size is large,the correlation is analyzed by random matrix theory,and the mean spectral radius(MSR)is used as the correlation quantitative index.Firstly,the line loss rate and the influence factors are constructed as matrix data source,and the sliding sampling window is used to obtain the window matrix of the sample,and the MSR of the computing window matrix is calculated.And the comparison matrix is constructed to calculate its MSR.The difference of MSR of the window matrix and the comparison matrix is worth the correlation size.Finally,an example is given to show the effectiveness of the proposed method.