The Development Of Feeder Terminal Unit For Distribution Network

With the fast development of electrical network, the requirement for the reliability of distribution net has been more and more high. The feeder automation (FA) is the most effective way to improve the reliability of distribution net so that it is the hot point of distribution network automation system (DA) at present. Thus, the Feeder Terminal Unit (FTU), as the core apparatus of the feeder automation, has been selected as the aim product by many manufacturers.First, in this thesis it presents automatic apparatus system, a new equipment of feeder automation, describes the functions of fault detection, fault isolation and automatic restoration of power supply in the non-broken-down sections, and discusses FTU action principles when fault occurs combining with actual running environment. The correlative techniques to achieve the monitoring function of FTU are discussed in details, including the calculation of the electric parameters in AC sampling. Also, the harmonic monitor and FFT are discussed specially.Secondly, this thesis describes its design of the hardware and software development. According to different function, the hardware part is divided into processor module, analog signals input and converting module, digital signals module, communication module, clock module and display module. The software part is divided into communication module, self-diagnosis module, data sampling module and data dispose module. The details on every module are provided. This system bases on two 16 bits microprocessor 80C196KC to sample 64 dots in a circle and deal with data in real time, using MAX125 as sampling apparatus. In such way, the frequency, the virtual value, the harmonic and power factor are acquired. It can achieve the intelligent control by way of cooperating with master station automatic apparatus system through adopting RS-485 communication standard. The software part presents the flow charts and brief introduction according to the program design. At the same time, linking with the special requests of DA in communication mode and agreement, this thesis introduces the communication technologies and explains the realization of the communication module conforming to IEC870-5-101. The anti-jamming techniques of shielding, filtering, grounding are applied in hardware part to prevent external disturbs as well.Finally, in the basis of development in hardware part and software part, this thesispresents the results of the primary tests and analyzes the causes of the existing errors. Also the approaches to reduce the errors are discussed, for example, improving the accuracy of the elements, raising he sampling frequency and so on. During the experiment, the online test between the PC and FTU is tried through the testing program in PC.In conclusion, it proves that the system can meet the requirement of reliability and price in FA, and be suitable for the improving of city distribution network.