Study On The Fault Location And Service Restoration Strategy Of Distribution System With Distributed Generators

In recent years, with the aggravation of environmental pollution, the increasing depletion of conventional energy and the increasing demand for power supply,multi-types of distributed generation (DG) as a new type of power supply for power system environmental protection has aroused wide attention of scholars at home and abroad. Although the DG with clean, environmentally friendly, pollution-free renewable and many other advantages, large-scale multi-types of access to distribution network has brought great impact, resulting in the relay protection system to malfunction, the traditional fault location and reconfiguration technology is no longer applicable etc..Therefore, in order to minimize the impact of multi-type distributed power supply to the distribution network, to ensure that the safety and reliability of the user power supply, in this thesis, first of all, the basic concept of distributed power generation, the principle of grid connection, the mode of operation and the change of power flow calculation after distributed power supply are briefly introduced and analyzed,and the influence of DG access to the distribution network from two aspects of stable operation of the distribution network and the change after the failure of electrical quantities. On this basis, this thesis adopts improved harmony search algorithm for fault location in distribution network, considering the traditional harmony algorithm is easy to fall into local optimal solution and the convergence speed is slow, this thesis based on the ranking method to update the memory database and dynamically modify the memory selection probability and probability of fine-tuning to improved harmony search algorithm was improved to a certain extent enhanced harmony algorithm, Through the simulation analysis, harmonic algorithm has the strong ability of global optimization and targeting efficiency in distribution network fault location.The complexity of fault restoration in distribution networks caused by natural disasters, as well as the traditional distribution network fault restoration algorithm is difficult to realize the restoration quickly for important user and the optimization of the global restoration. Therefore, this thesis under the premise of considering distributed power and the important user, adopting the breadth-first search quickly restore skeleton channel and improved ant colony to restore the rest load two-phase type recovery strategy,to ensure that the user can in the shortest possible time to restore power. Considering the over-limit node voltage may be caused by the access of distributed generation and the fault restoration, this thesis adopts the method of adjusting the on-load transformer tap do utmost to ensure the node voltage in the range of stability, to gain reliable fault recovery scheme. Finally, compared with the traditional ant colony algorithm, the feasibility and effectiveness of the proposed restoration model and the improved method are verified.