Yu Wenbin

The Analysis on Temperature Characteristic of Fiber Optic Current Sensor Ratio Error

This paper researched on the error ratio of fiber optical current sensor (FOCS) induced by temperature drift. The principle about the influence of temperature fluctuation on FOCS was explained. Based on the principle, the math module of the influence of temperature on linear birefringence and the influence of linear birefringence on FOCS were established to deduce the math module of the influence of temperature on FOCS. By the math module, the reason of FOCS error drift was described to explain the relationship among temperature, linear-birefringence and FOCS ratio error. In the range of testing temperature, both the ratio error of FOCS and linear birefringence had a linear relationship with temperature. The experiment results conformed theoretical analysis. The FOCT ratio error had a linear relationship with experiment temperature 10-60°C.

Research on Magnetic Crosstalk Characteristics of Straight Light Path Type Optical Current Transformer

The straight light path type optical current transformer is exposed to the magnetic field interference in the three-phase power system. In this paper the mathematical model of magnetic interference rate (MIR) of straight light path type optical current transformer was established, and the MIR characters of straight light path type optical current transformer were researched. The research showed that the structural parameters of straight light path type optical current transformer are the key factors influencing the MFI of straight light path type optical current transformer, and the study discovered that the MIR of straight light path type optical current transformer decreases with the decreasing length of the magneto-optic crystal or distance between the magneto-optical and the current to be measured. Basing on that, an optimization method was proposed to improve the anti-interference ability of straight light path type optical current transformer by reducing the distance between the magneto-optic crystal and the current to be measured. The experimental results showed that the error of straight light path type optical current transformer induced by magnetic crosstalk decreased by at least one order of magnitude when the distance between the magneto-optical and the current to be measured reduced from 20cm to 4.4cm. The experimental results are consistent with the theoretical analysis conclusions, and that demonstrates the correctness and practicality of the proposed optimization method.

Analysis of the Functional Mechanism of the Interference Magnetic Field on Straight Light Path Type Optical Current Transformers

The straight light path type OCTs feature simple optical paths and high reliability, but are vulnerable to interference from the external magnetic field. In this paper, the method of Jones matrix is adopted to establish the sensing models of the straight light path type OCTs for analyzing their sensing characteristics and thus revealing the functional mechanism of the interference magnetic field. It is found from the analysis that the interference magnetic field works either by changing the sensing coefficient of the straight light path type OCT or by changing the target magnetic field, moreover, the analysis also shows that the impact of the interference magnetic field on the sensing coefficient can be neglected, but the impact is significantly seen on the target magnetic field, which thus can significantly reduce the measurement accuracy of the straight light path type OCTs. The simulation results show that, under the action of 1000A interference current, the measurement error of the straight light path type OCTs is 2.91%, which is far beyond the accuracy level limit of 0.2, so the simulation results coincide with the theoretical analysis. The research in this paper can lay the theoretical basis for analyzing and optimizing the magnetic resistance characteristics of the straight light path type OCTs.

Optimization Design of Optical Current Sensor with Magnetic Concentrator Ring for Gas Insulated Switchgear

To improve the flexibility and practicality of the magnetic concentrator ring optical current sensor (OCS), the extra-hoop OCS scheme with large size magnetic concentrator ring and double-incision structure was proposed. The sensing character of the extra-hoop OCS was analyzed and the results showed that the double-incision structure, leakage flux and permeability are three key factors affect the sensitivity and the linearity of the extra-hoop OCS and there are specific relations between them. The magnetic circuit model and sensing model were established, and the optimum scheme was designed. The precision of the designed extra-hoop OCS reaches the 0.2-class.

Calculation and Theoretical Analysis on Mini Optical Current Transformer

In the article, relationship between sensing length and sensing performance has been studied. In order to realize microminiaturization of optical current transformer, sensing structure must be simplified first. Considering measure performance and material character, straight light path type optical current transformer which is made of block glass is the simplest structure. The Faraday optical rotation curve which reflects the relationship between Faraday angle and magneto-optical material length has been obtained. This paper has put forward a simple algorithm of knee point, which could fix the knee point on curve fleetly. The magneto-optical material length on knee point has a highest utilization ratio. According to the research, knee point position is related with glasses location and sectional shape of conductor. So the best location is the place nearest to conductor.

Determination of Response Threshold of Optical Current Transformer

For an all-electric ship, power system is not only the energy source of power distribution, but also the energy source of ship driving system, so it is the development direction of ship in future. The optical current transformer is very important in all-electric ship. Its necessary to do some further microminiature research on the optical current transformer used in all-electric ship. The first problem is relationship between sensing length and sensing performance has been studied in this paper. According to the relationship between accuracy and resolution, resolution threshold has been presented and defined as lower limit of magneto-optical material length.