Research On Low Voltage Unit Of Photoelectric Hybrid Current Transformer

A current transformer is very important equipment for system protection and electrical measurement in electrical power system. Its accuracy and reliability have significant impact on safety, stability, and efficiency in power system. A photoelectric hybrid coupling current transformer has a lot of obvious advantages over a traditional electromagnetic current transformer. It will definitely find more and more applications. Low voltage side is a very important part in photoelectric hybrid coupling current transformer implementation. It has direct impact on system precision and reliability. It is the focus of this paper.In this paper, various types of current transformer principle with the advantages and disadvantages are studied. It presents a hybrid optoelectronic current transformer design. On the part of the theory and implementation have made a detailed analysis. The paper mainly completed the study design and implementation of the low-voltage side part. FPGA has character of high integration density, high speed, and high reliability. DSP has its super computational capability. By combining of superiorities of these two devices, the FPGA+DSP design has been proposed to implement a high performance photoelectric hybrid current transformer at its low voltage side.In this article detailed the circuit design of the hardware system of low pressure side, chip selection and the circuit implementation and debugging of the various parts. At the same time, the composition of software systems and programming ideas to do a specific elaboration, which may include synchronization signal extraction, data of the Manchester decoding, the start code detection and information code extraction, CRC checksum, the restoration of three-phase signals and data in real time output. Finally It gives the overall system simulation, testing and hardware debugging, verify the function of the system implementation.The test results have proven that the proposed system design can perform the expected functionality of photoelectric coupling current transformer at low voltage side. The proposed system integrates the superiority of both FPGA and DSP. It can better meet the power system's requirements in the high-speed data processing, large data quantity and complex operation. It also has merit of being simple in structure and easier for modification. It is worth of further investigation.