Research On Single-three Phase Power Flow And Network Reconfiguration Of Distribution System

Power flow analysis and distribution network reconfiguration are two importantissues in distribution network automation. How to improve the computing speed andcomputational efficiency has been a popular research subject in academic andengineering circles.Aimed at the above two problems, a exploration and study have been done in thisthesis and many satisfactory achievements are obtained. The contents andachievement of this thesis are as follows:1．This thesis proposes a hybrid single-three phase model and the correspondingalgorithm. In the hybrid model, three-phase model is considered at the network partwhere unbalance is obvious and single-phase model is considered where unbanlanceis negligible. And these two parts are connected by an equivalent network interface. Inorder to improve the calculation accuracy of the single-three phase power flowanalysis, a direct calculation accuracy indicator, the current on the equivalentadmittance at the interface, is proposed. Further more, measures to dynamically adjustthe interface position are proposed. Change the position of the interface dynamicbased on the current at the interface at each iteration, until the current is small enough.Results of the examples show that, the hybrid single-three phase power flow model,algorithm and the interface movement strategy proposed is effective.2．In this thesis, the distribution network is firstly simplified to achieve asimplification network according to the structural characteristics, then, a fast methodto judge the topology radial property for a reconfiguration solution based on basic-treeis proposed, and is further added to the method of network reconfiguration based onPSO to accelerate the calculation speed. The results of the examples show that, themethod proposed in this paper has a distinct advantage in the calculation speedcompared with traverse method that is popularly used, and as the size of the networkincreases, its superiority is more obvious.3．This thesis proposes a new distribution network reconfiguration method basedon the Mayeda’s listing tree method. The basic process is as follows. The distributionnetwork is firstly simplified to achieve a simplification network which is equivalent intopology. Then, a continuous tree branch exchange operation that can obtain any spanning tree of the graph is proposed base on the Mayeda’s listing tree method.Combining the simplified network and branch exchange operation, a new encodingmethod for the evolution of PSO (Particle Swarm Optimization) algorithm ispresented. Further, in order to overcome the shortcoming that the PSO algorithm iseasy to fall into the local minima, FFM (filled function method) is proposed in orderto achieve a better feasible solution out of the local minima in the optimizationprocess of PSO. The results of the examples show the effectiveness of the algorithm.