Self-adaptation compound feedback optical current transformer and method for determining current

Abstract

The invention discloses a self-adaptation compound feedback optical current transformer and a method for determining current and belongs to the field of electric system high-voltage circuit current measuring and controlling applications. The self-adaptation compound feedback optical current transformer comprises a magneto-optic sensing unit which is a double-ring compound magneto-optic sensing unit and N single-stage magneto-optic sensing units. The current transformer is formed by arranging an intelligent following-adjusting light source, optical splitters, front-mounted optical detectors, rear-mounted optical detectors, the magneto-optic sensing unit, collimators, polarizers and polarization analyzers according to an optical transmission optical path. Meanwhile, the invention provides a method for determining current. The compound sensing technology is adopted, and therefore the problem that because of time-varying parameters, the measurement precision of the optical current transformer is low is solved; the optical sensing loop close-loop negative feedback structure is adopted for eliminating random variations, caused by environment temperature, of light intensity on the background of the optical current transformer, and the measurement precision is further improved.

Description

technical field [0001] The invention belongs to the technical field of electric system high-voltage line current measurement and control application, and in particular relates to an adaptive composite feedback optical current transformer and a method for measuring current. Background technique [0002] The current transformer is an important equipment for power system measurement and protection control. After long-term development, the accuracy of the electromagnetic current transformer in measuring the steady-state current can reach a few ten thousandths, or even higher; but in the case of a short-circuit fault, the electromagnetic current transformer Severe magnetic saturation occurs in the relay, which leads to the distortion of the secondary output current waveform and cannot describe the transition process of the short-circuit current. This is one of the main reasons for the relay protection to malfunction and refuse to operate. In the future, the monitoring and control...

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Problems solved by technology

The transformer can run stably for a long time and has high measurement accuracy; but the invention also has shortcomings, which are shown in: the method uses multiple optical paths to average to improve the measurement accuracy when measuring the alternating current, due to the Faraday magneto-optical effect In the optical current transformer, parameters such as linear birefringence and Verdet constant are multiplied by the Faraday rotation angle. These parameters are time variables in the actual operation process, and the method of this patent cannot be completely separated. Such an optical current transformer There is also limited improvement in measurement accuracy

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