Power Flow Calculation And Related Issues Study Of Urban Distribution Network Closing Loop Operation In Huhehaote City

Loop closing operation in distribution network is a necessary step of power systems operation,in such model,when it comes to overhaul or load shift,by using closed-loop operation,load can maintain power supply,but it may generate large circulation flow affecting security and stability of the system.Operators often decide whether to operate by experience.Being afraid to endanger whole network of power systems,they always apply closed-loop operation conservatively at the price of power failure.So it is necessary to develop a computer-aid decision-making software which can offer some guidance to operators before making the operation,it has pragmatic values.This topic is initiated by production department of Hohhot electric power company.Therefore,in this thesis,the operation of closing loop in distribution system is carefully studied and a network model fit for calculation is explained.Such a model is applied in flow calculation and leads to a more exact and reasonable calculation result.On the basis of analyzing the features of distribution network structure and the merits and drawbacks of existing load flow calculation method for distribution network,a superposition principle and the forward/backward sweep method based algorithm of load flow calculation for meshed distribution network is put forward.The meshed network is converted into pure radial networks by applying the superposition principle.Theoretical study on convergence of forward/backward sweep algorithm which is fits for radial distribution power flow calculation is done in the paper.A searching method based on the adjacent nodes table is presented to search the loops and obtain its impedance matrix.Based on making the model of Hohhot electric power system and inputting parameters to the model, the loop-closing software has been used in real-time calculation,and the field tests have proved that the presented method is effective.