With The Grid Fault Location And Isolation Problems

With the reconstruction of the electric network in China, the automatic system for the fault section diagnosis and isolation in distribution networks is required, especially in those networks where faults often occur. When a fault takes place in a certain network, the real-time information is collected from breakers and sectionalizers by FTUs (Feeder Terminal Units) or RTUs (Remote Terminal Units) and is send to control center. Then, according to the information, the fault section diagnosis software can locate the fault section. However, because FTUs and RTUs are usually installed outside, they are inevitably influenced by bad weather, electromagnetic disturbance etc. Therefore, the real-time information is often distorted, which asks us to find a method that has fault-tolerance performance. Besides, because distribution networks are complex and changeful, we must consider the adaptability of the algorithm.Researchers note that GA (Genetic Algorithm) can find global optimum solution and can correct the mistake in the data automatically. At the same time, matrix algorithm is simple, practical and quick, therefore, it is also considered by researchers.In this thesis, a thorough and systematic research is made on fault section diagnosis and isolation of distribution networks, including basic principle, topologic model, all sorts of resolution, etc. An emphasis analysis and discussion is made on the application of the fault section location arithmetic to the complex multi-source power distribution system based on GA and matrix algorithm. The main content is as follows:This paper summarizes current methods to fault section location, analyzes their advantages, disadvantages, feasibility and localization. On the basis of that, three standards are put forward to appraise all kinds of methods. Then, take the difficulty of fault section location into account, choose GA as the method to fault section location.The further research is made to fault section diagnosis and isolation ofdistribution networks based on matrix algorithm. Through analyzing the construction of the information matrix, we take the direction of the short circuit current, and reconstruct the information matrix. The refined matrix algorithm is able to locate multiple fault sections in multi-source distribution networks.The further research is also made to fault section diagnosis and isolation of distribution networks based on GA. A new fitness function is developed. The refined GA is able to locate multiple fault sections in multi-source distribution networks, so it is more suitable for complex fault diagnosis in distribution networks.Then, a network model is presented, in the paper for the application of the fault section location arithmetic to the complex multi-source power distribution system. The model takes the directions of variable related to the short circuit current into account. After the positive direction decided by the assumed power flow of some source being considered, the fault section location in the multi-source distribution system is translated into the location of the single source system.Finally, the results of simulation (programmed with C language) show that this method is effective and practical: whether it is the single source system or it is the multi-source system, whether there is one fault or there are multiple faults, when the distortion in the real-time information appears, GA can correct the mistake automatically and locate the fault section accurately.