Research On All Optic-Fibre High Voltage Transducer Based On Modular Interference

In modern industrial power transportation system, instrument transducers are prerequisite equipments. They can provide the important information for measurement, control and protection in power system. However, with the high voltage and large power demands in power grid, traditional instrument transducers based on electromagnetic induction and capacitance divider have a lot of disadvantages. And a novel Optical Voltage Transducer (OVT) is expected urgently in power system and has attracted eyes of institute and scientific research department.This paper reviews the development actuality, basic theory, advantages and disadvantages of OVT in the world. And an optic-fibre high voltage transducer which has the capacity of compensating the environment temperature perturbation automatically is brought out. This paper studies the principle of modular interference in Elliptical core Polarization Maintenance Fiber (E-core PMF) and the rule of interference output intensity distribution in theoretical and experimental scope. The high voltage transducer, which is based on modular interference in E-core PMF and converse piezoelectric effect of quart crystal is designed and discussed detailedly in the paper. And the optimized transducer head configuration of the OVT is studied theoretically with finite element method. The general experiment setup and result of the transducer prototype is also fulfilled in this paper. The contents of this study are as follow:First, the relationships between interference output lobes and modular phase difference of several low order polarization modes in perfect circular core step-index fibre are analyzed with optic-fibre mode theory, and some 3D plots of interference output intensity is given. Then, the calculation for discovering the rules of modular phase difference and interference output intensity distribution of LP0 1 and LP1e1v en(even LP1 1 mode) in E-core PMF is fulfilled.Second, the scheme of a novel optic-fibre high voltage transducer which based on modular interference in E-core PMF and converse piezoelectric effect is designed, and the mathematical model of the sensor system is also established. This paper studies the characteristics of some important components in the transducer system. The dual mode wavelength, propagation difference and modular beat length of the E-core PMF are gotten by calculating the propagation characteristics of several low order modes in E-core PMF with equal-area theory and effective refractive index method. At the same time, the primary character and special demands of quartz crystal and PZT in the OVT are analyzed. And an excellent signal process circuit is designed in this paper.Third, the electric field distribution in the transducer head which is composed of four electrodes and three quartz crystal cylinders is simulated with finite element method. And an optimized configuration of the transducer head is designed after comparing the electric field distribution rules at different electrodes shape, size, material, and different sustain tube and different insulated gas.At last, the propagation characteristics of the E-core PMF is researched experimentally. As the main object, the feasibility and measurement accuracy of the all optic-fibre high voltage transducer prototype is validated with a high voltage generator, and the experiment result is also given.This paper achieves a mass of theory and experiment study on a high voltage transducer prototype based on modular interference and converse piezoelectric effect, which can provide valuable reference for the practical design and application of OVT.