Power Flow Analysis For Multi-Source Distribution Network Based On Splitting-Compensation Method

The power flow calculation of distribution network is an important part of distribution network analysis,which provides a favorable data support for the further analysis of the transient stability,load forecasting,fault analysis and power grid planning of distribution network.With the rise of new energy and the development of technology,the power supply mode of dual-power supply and multi-power supply in distribution network become more and more widely used.However,the more the multi-power supply connecting to network,the more complex and difficult for people to predict the power flow direction of the system,and the traditional power flow calculation method is no longer applicable to the distribution network with multi-power sources.Further research on power flow calculation method for dual-power supply and multi-power supply can provide better quantitative analysis basis for further in-depth analysis.The main contents of this paper are as follows:Firstly,This paper summarizes the classical method of traditional power flow calculation of distribution network,analyzes the advantages and disadvantages of several classical methods,and studies the power flow calculation of dual-power supply and multi-power supply system combined with the advantages of the classical algorithm.Secondly,this paper puts forward the calculation method of branch splitting method of dual-power flow.Using the branch splitting method for splitting processing,the traditional forward and backward sweep method is used to obtain the power flow of the sub network after the disconnection,and the superposition theorem is used to compensate the current of the branch to the corresponding sub network.At the same time,in order to solve the problem that the inverse of the large node admittance matrix is likely to be wrong in calculation,this paper proposes the direct method to obtain the node impedance matrix and avoids the inverse process of the large node admittance matrix.Finally,the correctness of the proposed algorithm was verified in the 28 node three-phase balanced system and the IEEE33 three-phase unbalanced system,the result shows that the proposed algorithm reduces the number of iterations.Thirdly,by using three kinds of droop control characteristics of distributed power coordination strategy,and combine the five order Levenberg-Marquardt algorithm(LM),people can solve the power flow in islanding micro grid correctly.Three kinds of droop controlled distributed generations with adjustable power are proposed.This paper discusses the distributed power system islanding droop character:istics;and establish the balance equation of islanding power flow calculation,which not only considering the droop characteristics of distributed power supply,but also consider the effect of variable frequency on load;finally,based on the five order LM optimization algorithm to adjust the direction and step size of iterations,and find the optimal nonlinear power balance equation set.The correctness of the algorithm was verified in the three-phase balanced IEEE6 node system and three-phase unbalanced 25 node islanding micro grid,and the algorithm is proved to have a certain improvement effect on convergence.