Research Of Analog Signal Transmission Method Via Optical Fiber

The importance of high voltage segregation is increasing all the time in such an era that science and technology is updating day by day. The idea of analog signal transmission by optical fiber at the high voltage and low voltage ends may help to solve the high voltage segregation problem in the potential transformer, because it will decrease production cost of transformer, make an effective segregation on high voltage, and enhance the accuracy and reasonability of the segregation signal obtained from the control center of the power station.In order to measure the voltage parameters of HVDC bus, this paper designs an approach that integrates digital signal transmission and optical fiber communications, by which this; industrial engineering problem is simplified and researched in a theoretical experiment. The research approach for this problem in this paper goes as follows. First, we take the produced 0-5V analog signal as the input signal in the analog signal fiber transmission unit. The A/D converter in the optical transmitting end will convert the input analog signal into corresponding digital signal, and converted digital signal output by the A/D port will be latched by the data latch at the same time. Second, the parallel/series converter in the transmitting end will convert the transmitted digital signal from parallel to serial for the convenience of later employment of CMI code. Third, CMI coder will encode the serial signal according to coding rules, and such signal will be transmitted to the optical receiving end through optical fiber. The received code stream will be decoded in receiving CMI decoder, and the decoded signal will be converted to parallel by the series/parallel converter. The output parallel signal should be identical to the previous parallel signal input by the transmitting end; if not error has occurred in the decoding. Fourth, D/A converter will convert the received digital signal into corresponding analog signal, and the undesired signal will be filtered away by a low pass filter, which is to ensure a more accurate value. Compare the obtained analog signal and the previous input signal. We can deem it correct if the difference is within a specific deviation range. The whole analog signal fiber transmission is completed when the above steps are finished. But in the last, the received analog signal should be processed by a microprocessor for the purpose of direct use in supply station, because we need to send the signal to the supply station in real life. Besides, it also provides convenience for the supply station in observing voltage stability.After conducting the experiment step by step according to the said approach, the final experiment result indicates that in the comparison between the output voltage signal and the input voltage, the result will be correct if the deviation does not exceed 1%. We can see from the above facts that the data measured by the research approach designed in this paper is of high accuracy and low deviation, and most importantly, it can solve the high voltage segregation problem.