Study On Laser-powered Current Transformer Based On PCB-Rogowski Coil

Along with the voltage grade of the national power grid rises ceaselessly, thetraditional electromagnetism style current transformer has exposed serious limitations,which Restricts its further applications. It is inevitable to design a new type of currenttransformer to replace the traditional current transformer. Because the technologies ofoptoelectronic, optical fiber communication and digital signal processing develop quickly,it will carry on a technology revolution in the aspect of measuring the high voltage andthe high current. This paper aims to study and design an active photoelectric currenttransformer. It can solve a series of problems which are the electromagnetism stylecurrent transformer is difficult to solve. The higher the voltage level is, the more theunique superiority can show.Active photoelectric current transformer has the good qualities of the provenelectricity optical sensing technology and the optical fiber technology, using the opticalfiber to realize the transmission of energy and information. In this paper, it uses theschematic design of the current transformer which is combined with PCB-Rogowski coiland the technologies of voltage-frequency conversion and photo-electricity conversion,and establishes the theoretical model between the current input and the frequency output.In this scheme, it converts the current signal into the light pulse signal which ismodulated by pulse frequency, then conveys the light pulse signal to the low voltage sidethrough the optical fiber, solving the problems of the insulation and the anti-interferenceexisting in the conventional current transformer. It focuses on studying the improvementof the current sensing probe and the design schemes of the laser energy supply systemand the optical fiber communication system. This paper puts forward the laser energysystem to solve the problem of the working power supply for the measurement circuit inthe high voltage side, which can offer dozens of milliwatts power and meet the workrequirement of the measurement circuit in the high voltage. In the low voltage side, ituses the digital demodulation scheme based on the microprocessor to calculate the pulse frequency signal, then get the digital signal output. Meanwhile, it restores the pulsefrequency signal to the analog current signal by using the analog-to-digital conversionchip. So this system can provide two ways of signal interface, which are the analog andthe digital. Its wavelet threshold denoising method provides a new analysis method forthe microcomputer analyzing and processing the signals.It gets the simulation curve of the test data by the MATLAB software, whichverifies the rationality and feasibility of the measurement system. In this paper，thedesign scheme of photoelectric current transformer meets the development needs of thenational electric power system, which requires the current measurement equipment iscomputerizable and intelligent.