| Summary: | 碩士 === 國立臺灣大學 === 電機工程學研究所 === 104 === After International Electrotechnical Commission (IEC) defined IEC-61850, it becomes a new reference for digital substation and creates a substantial market for electronic instruments. Many countries in Europe or America adopts IEC-61850 as the new standard for their substation in the future. On the other hand, State Grid Corporation of China (SGCC) referred to IEC-61850 and published similar technical documents. In the conventional substations, analog instruments are used to implement function of protection or measurement with copper used as wires. However, EMI problems become more important as time goes by. Besides, there could be problems resulted from different manufacturer such as compatibility and interoperability between devices, and these are implicit cost for power corporation. Therefore, IEC-61850 defines basic rules that manufactures must follow and it adopts optical fiber as media to reduce the effect of EMI. Merging Unit is to convert the values sampled from potential transformer or current transformer to a special format to fulfill Sampled Value protocol, specified in IEC-61850-9-2. After converted, the data is sent to Ethernet process bus, and the Intelligent Electronic Devices (IEDs) connected to the Ethernet apply this data to implement protection and measurement. In this research, embedded controller, CompactRIO-9067 developed by National Instruments, is adopted as the development platform of Merging Unit because of the advantage of modularization and a suite of Intelligent Development Environment (IDE) to help us save a lot of time on layout and system integration. The prototype of Merging Unit in this thesis uses GPS as the source of time synchronization, also it completes the sampling of voltage and the transmitting of data packets under Sampled Valued protocol. The future work is about sampling current and using IEEE 1588 as second source of time synchronization.
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