Research On Optical Measurement Of The Electric Parameters In High Voltage Electric Power System

This paper explicitly describes the optical measurement of the electric parameters in the high-voltage electric power system, and an optic fiber large current sensor based on Farady magnetooptic effect and an optic fiber high voltage sensor based on the linear transformation characteristic of LED are developed from research on both theory and experiments. By combining the two sensors to form a synchronous system, the task of harmonic analysis, phase demodulation, power and wattless power computation is accomplished, which helps to monitor and control the electric power system. In laboratory, this system has fulfilled the measurement of simulant large current and high voltage, with the precision better than 1% to the fundamental wave. As to the harmonics, the precision satisfies the state standard known as GB/T14549-93. And the results in laboratory show a high temperature stability in this measurement system.Concerning the problem of the frequency instability, slight but not negligible, in electric power system, this paper discusses the resultant error in measurement in detail and develops an error-correction interpolated algorithm in frequency domain. Taking advantage of the high calculating speed of PC, the measurement error in frequency, amplitude, and phase are well eliminated.This system based on optical effects is greatly superior to the traditional electromagnetic PT,CT in the following aspects: electric insulation of the low voltage side from the high voltage side through optic fiber, no electrical connection and electromagnetic interference in signal transmission, avoidance of magnetic saturation, small in volume and light in weight. It has a prospective future in the electric power system.