Study And Design Of Expert Three Phase Power Flow For Distribution Network

Electric energy plays a more and more important role in the development of modern society and people's life,the demand for power supply reliability and power quality is also higher and higher.Distribution system is an important part of power system,it directly affects the user's electricity quality and the reliability of electricity,the importance of distribution system analysis is self-evident.Power flow calculation is the most basic and core calculation in distribution system analysis,it is used to analyze and evaluate the operation status of distribution system.The results of power flow are the basis of steady state analysis,transient analysis and short circuit calculation,which has the basic position and function in the analysis of distribution system.In distribution system,because of the asymmetry of three-phase parameters,the unbalance of three-phase load and other problems,three phase power flow calculation must be used.In the three phase power flow for distribution network,the convergence problem has received extra attention.This thesis studies the problem of expert three phase power flow for distribution network.The algorithms are designed from the two aspects of improving the convergence of the calculation and analyzing the reason that the power flow calculation does not converge in MATLAB.In the three-phase power flow calculation,it should be considered that the phase deviation of the transformer.If the flat value start method is used to set the initial value of each node voltage phase angle,the voltage phase angle of some nodes will be far away from the solution of power flow calculation,leading to divergence of power flow calculation.A new initial voltage setting method for three-phase power flow calculation is put forward,fully considered the voltage phase angle deviation of transformer.By searching the branch in the distribution system,along the search path,then the initial value of the phase angle of each node voltage is set according to the digital label of different branch connection groups,the initial voltage value of each node is closer to the solution of the power flow calculation.So improving the convergence of three phase power flow calculation in distribution system.The input data of distribution network system is the data source of power flow calculation in distribution system,and it is the basis of power flow calculation.Its validity greatly affects the accuracy of the power flow calculation results.When the calculation shows that the calculation does not converge or the calculation result is not normal,based on the expert's experience,this thesis designs expert three-phase power flow for distribution network,the data is checked so as to find the abnormal data.The distribution network connectivity,transformer connection group and the correctness of solving the equation have been examined,to help researchers analyze the reasons for the non-convergence of power flow.Finally,an example is given to illustrate that the proposed algorithm has strong practical value in improving the convergence of power flow calculation and in analyzing the causes of non-convergence of power flow calculation.