Distribution Network Reconfiguration Method Based On Electrical Distance Of Transmission Impedance

Distribution network reconfiguration is an important way to improve the safety,economy and power quality of distribution network operation.It is of great significance for the construction and application of distribution automation system.With the integration of distributed generation into power grid,the operation of distribution network has changed from single-source mode to multi-source mode.The randomness and uncertainty of distributed generation make the reconfiguration of distribution network more complex.Therefore,the research of distribution network reconfiguration with distributed generation has important theoretical and practical significance.Firstly,an example of 7-node distribution network is given to illustrate that the Optimal Flow Pattern algorithm can not obtain the optimal reconfiguration result.Then the reason for this phenomenon is explained theoretically and experimentally,that is,the problem of the optimal flow mode method:the optimal flow mode method only considers the current information but neglects the voltage information.Incomplete information may lead to inaccurate results.Therefore,this paper argues that the distribution network reconfiguration based on complex power which contains more complete electrical information will be more accurate.Most of the existing algorithms can’t ensure the speed and optimal solution at the same time.Therefore,this paper proposed that using electric distance calculation method based on transmission impedance to solve reconstruction problem.The algorithm is a heuristic algorithm.For a loop network with all switches closed,the minimum loss structure of a power flow section is obtained by successive unwinding.The loop-opening operation follows three criteria:selecting the power supply path with the lowest efficiency;breaking off the weakest power supply path when there are multiple power supply paths for the candidate load;disconnecting the branch with minimum power transmission when the path to be broken is serially powered by a plurality of branches.In order to avoid local optimum,this paper proposed a modified way reserving the breaking scheme within the threshold range every time.Finally the numerical example of IEEE33 nodes distribution network show that the proposed method can get the optimal solution consistent with enumeration method,and the reconstruction speed is fast.Aiming at the reconfiguration of distribution network with distributed power sources,this paper adopted the method of dividing the multi-power network into several single-power supply networks according to the power component theory,and then transforming multi power sources into integrated power source from the load.Analogize the process of distribution network reconfiguration under single power supply according to the parameter characteristics of equivalent integrated power supply.The results of IEEE 14 nodes system with distributed generators show that the proposed method is also applicable to active distribution network with distributed generators.