Research On Reconfiguration Of Distribution Network With DG Based On Load Change

In order to alleviate the global energy crisis and environmental pressure,improve the utilization efficiency of energy and promote energy conservation and emission reduction as well as the renewable energy's development,distributed generator(DG)has become an emerging way of energy utilization gradually.A large amount of connection of distributed power supply will have a great impact on the safe and stable operation of the power distribution system,because distributed generator has such characteristics as dispersion,random variation.The reconfiguration of distribution network is an important means to realize its safe and reliable operation.Therefore,this paper studies the method of reconfiguration of distribution network,considering the change of load and the uncertainty of distributed power output.Firstly,in terms of the calculation of power flow of distribution network with distributed power,this paper divides the distributed power into four types of node:PQ,PI,PV,PQ(V)on the basis of the forward-backward sweep calculation method of the traditional distribution network,establishes the calculation model of power flow of distributed power respectively,offers the forward-backward sweep calculation method that is also applicable to the node layering of DG and finally makes an analysis for power flow of distribution network with all types of DG included.Secondly,in terms of the static reconfiguration of distribution network with distributed power,this paper establishes the static reconfiguration model of distribution network.The active energy loss of distribution network is taken as the objective function,and the integer ring coding scheme is used to encode to greatly reduce the dimension of variables.An integer coded quantum particle swarm optimization algorithm is concluded after the improvement of the quantum particle swarm optimization algorithm.In order to eliminate the invalid solution quickly,an infeasible solution method of switching loop matrix and node hierarchical strategy is proposed.Finally,the IEEE33 node system and the PG&E69 node system are taken as examples to test and analyze the distribution network without DG,the reconfiguration of the distribution network with single type DG and the reconfiguration of the distribution network with multiple types of DG.Finally,in terms of the dynamic reconfiguration of distribution network with distributed power concerned with change in load,this paper establishes a multi-objective optimization model which demands the minimization of the total active loss and the total number of switching actions in the whole time interval of the distribution network and proposes a Multi-period Two-step Optimization Strategy for Dynamic Reconstruction of Distribution Network.The time interval of the minimum loss of active power loss is preliminarily divided,upon which the second optimal reconstruction is carried out on the period of minimization of the number of switching operations and then the best reconfiguration project can be decided.Finally,the dynamic reconfiguration of distribution network is tested and analyzed with IEEE33 node system as an example.