Research On Distribution Network Reconfiguration And Fault Recovery With Distributed Generation

As the middle bridge linking transmission network, distribution network in the state of stable, reliable and economical has important influence. Distribution network reconfiguration is the reflection of self optimization and self-healing, it is the important assurance of reducing the loss of network, improving the quality of electric power and recovering power supply.The traditional power flow model of distribution network has been changed due to the access of DGs. The situation changes the loss and node voltage of power grid. Therefore, how to optimize operational economy, stability, and solve fault recovery problem of the distribution network containing DGs through reconfiguration has an important practical significance.The paper aims to research two aspects which are operation optimization and fault recovery of distribution network.The main research work is as follows:The power model and node type of each type of DGs are established. Dealing with some difficult points in power flow calculation, The other types of nodes are transformed by the method of reactive power compensation and reactive power conversion.Effect of uncertain output of distributed generation, The probability calculation based on two points estimation is proposed to improve the efficiency and accuracy of power flow calculation.In the reconstruction of power supply path, according to the distributed power supply is divided into static reconfiguration and dynamic reconfiguration strategy. The topology is simplified through the distribution network to the initial complex. Simplifying the calculation process. The introduction of generating trees without duplications, simplify the network starting from the basic tree to through the radiation type network structure tree branches and even the support exchange non repeating, radiation type constraint checking without repetition in the optimization,reduce redundancy, improve the efficiency of power supply path optimization. With the new swarm intelligence optimization algorithm- dynamic improvement of "Teaching Learning Based Optimization algorithm", to improve the global optimization ability of dynamic optimization.In the dynamic optimization, because the output of distributed power with time uncertainty changes.Based on the probability of scene model construction, proposing the influence of the time scale of the scenario analysis method to describe the distributed power supply based on random output.This method can be well adapted to the influence of the wind turbines photovoltaic output of intermittent power distribution system,in accordance with engineering practice, for the power supply path the intelligent distribution network real-time optimization provide certain theoretical guidance.In the process of recovery of fault in distribution network,considering the multi-objective and multi constraint situation.To adapt to the operating characteristics of the distribution network, which is comprehensive, aiming at the islanding problem, The two stage of processing method is adopted, CSP model can apply to multi point power access complex situation, and applying to the first stage of islanding to find feasible solution. The second stage voltage index evaluation model on the initial solution by modified appraised according to) to find the optimal solution; finally on the island and the rest of the network model of switch combination optimization, to obtain the final containing multiple types of DG access to distribution network fault restoration scheme.The IEEE33 bus system and 69 bus system are examples to verify the proposed method, the results show the validity and feasibility of the proposed method.