Design And Realization Of A Comprehensive Feeder Terminal Unit

At present, with the fast development of economy and the standard of living, the need for power energy increased. It encouraged the power system to grow faster. And the power grids were enlarged continuously. At the same time, with the development of technology and high tech products, the requirement for power energy with better quality and reliability increased. Traditional structure, protection and management mode for distribution network do not suit for the economy growth. New distribution management methods are urgently required. Distribution automation is to monitor, control and protect the power equipment in the distribution network. It mainly consists of distribution management and feeder automation. There are two modes for feeder automation nowadays. One is called distant centralized monitoring and controlling system; the other is called local automation system. The former is growing with the development of computer, network and communication technology. The facilities in the distribution network are controlled and protected in a full-scale under this mode. The load data and parameters of power facilities are accurately acquired. When there is a fault in the distribution line, the substation system will find the exact location of the fault and isolate it. Then the system will help to restore the healthy part in a very short time. The distant centralized monitoring and controlling system is the advanced form of distribution automation. It will bring the power distribution system full-scale maintenance. But this automation mode highly relies on communication system. It is a fatal limitation because the automation system cannot work when there are certain errors in the communication system. Besides, high cost is another flaw. The local automation mode is comparatively simple in its structure. It mainly consists of reclosers and sectionalizers. The function of fault location and isolation is realized through the cooperation of them in which there is no need for communication network. But this mode cannot provide the full and fast monitoring and protection of course. Each has its strong points. Under this background, this dissertation proposes a feeder automation system with a comprehensive function. This system can deal with the situation when there are problems in the communication system. Also, a new type of Feeder Terminal Unit (FTU) is designed and realized combined the merits of the distant centralized monitoring and controlling system and the local automation system. It is the key component in the comprehensive feeder automation system. It can automatically recognized the communication fault and choose an adequate protection mode. The reliability of the power distribution system is enhanced by this system.