| With the trend of larger capacity and higher voltage of power grid in China, the improvement of the digital measurement and control is the basis for the high reliability and intelligence of the transformation equipment. And also it plays an important role in the safe production of electric power. With the constant development of the integrated substation automation technology and the photoelectron technology, further improvement on the secondary measurement and control and the full digital operation of substation is an inevitable trend.This paper describes the fundamental of photoelectric transducer, fiber digital combiner, synchronizer, intelligence unit, and photoelectric power meter, also the corresponding digital measurement and control circuit. Comparative analysis of the digital devices and the conventional devices is presented. Based on Inner Mongolia Power Grid 220kV Duerbote Substation digital rebuilding engineering, the overall reconstruction scheme for the information collection, transmission, processing, and output of the substation's key measurement and control circuit are described. Sampling synchronization, electromagnetic interference and capacitance coupling derived from optical cable transmission, and other problems included in the scheme are investigated. Rebuilt substation operating results show that the digital secondary measurement-control circuit increases the speed of data transmission, reduces energy loss in transmission, minimizes the transmission error.In view of the present situation that there is no universal technical standard for the digital substation equipment maintenance and testing, standards and specifications for maintenance and testing are studied, related specifications for equipment calibrating are proposed, all of which provide advantages for the digital substation equipment maintenance and testing, and ensure the equipment running reliably. |
