Research On Optimization And Application For Network Reconfiguration Of Power Systems

The Operating conditions of modern power system are complex and changeable,as a result,widespread blackout couldn't be avoided fundamentally.As the scale of power sys-tem becomes larger and the modern society is more dependent on the power supply exces-sively,the damage due to widespread blackout is more and more severe.Therefore,as one of self-rescue measures,the research on power system black-start restoration and its opti-mization technique is of great importance to relieving restoration burdens,speeding up the system restoration process,reducing the economic loss and social influence resulting from faults.After thoroughly investigating the previous work about the black-start issue,and com-bining with the technology projects of state grid corporation,the optimization technique about network reconfiguration and power system restoration with pumped storage station as the black-start power supply has been studied.The main work of this thesis is described as following:1.To solve the oversize dimensions of optimal searching problem for complex power systems,dimensionality reduction and optimization technique about network reconfigura-tion are studied.A kind of network-reconfiguration which search for the node as a search object is proposed.Generally speaking,for complex power system,the number of its nodes is less than lines.So,the method search for the node as a search object can reduce the di-mensionality of optimal searching problem.Network-reconfiguration with introduction of an improved ant colony algorithm introduces an improved ant colony algorithm to net-work-reconfiguration.A trunk line is obtained by improved ant colony algorithm before op-timizing backbone grid.The states of some lines are confirmed by the trunk line,so the di-mensionality of follow-up optimal searching problem is reduced.A kind of method to select network-reconfiguration based on Dijkstra algorithm is proposed because of the drawback of existing method for network connectivity assurance.The validity of the proposed meth-ods is verified by IEEE 118-bus system.2.Multi-objective network reconfiguration strategy for power systems considering restoration rates of lines.Restoration rates of lines are transformed into restoration rates of nodes,and the restoration rates of nodes are obtained by Monte Carlo method.Three objec-tives are included in the developed network reconfiguration model,namely maximizing the total number of the restored power load,minimizing the time for establishing a network frame,and maximizing the restoration mean rates of nodes in network frame.The differen-tial evolution algorithm is employed to find the optimal strategies.The correctness and va-lidity of the proposed methods are verified by IEEE 3 0-bus system.3.The black-start processes in some power grid with pumped storage station as black-start power supply are analyzed.Then the backbone-network is obtained by the pro-posed dimensionality reduction methods for network-reconfiguration and multi-objective network reconfiguration strategy.