Jian Jiang

A Fiber Bragg Grating Tension and Tilt Sensor Applied to Icing Monitoring on Overhead Transmission Lines

A novel ice monitoring system for the overhead transmission lines based on fiber Bragg grating (FBG) sensing is proposed in this paper. Compared to the existing systems, this system has several unique advantages, such as unnecessary power supply onsite, excellent ability for avoiding electromagnetic interference, and long lifespan. First, two near-elliptical-shaped concavities with FBG in each side are designed on the column structure to improve accuracy in measuring eccentric load. Then, a high reliability and high resolution tilt sensing section is developed based on a beam of uniform strength where an FBG is fixed on. Finally, an unforced FBG is placed in the sensor to solve the cross-sensitivity of strain and temperature in FBG sensing. Tension and angle experiments are conducted in our laboratory to calibrate the sensor. The tension experiment results indicate that the sensor is sensitive to tension, and the sensitivity and resolution of the sensor are 0.0413 pm/N and 24.21 N. The results of the tilt angle experiment show that the sensitivity and resolution of the sensor is 16.17 pm/° and 0.0619°. The temperature effect on the tension and angle measurement, evaluated by putting the sensor in an oven, is less than ±0.3% and ±0.38% separately. A 250-h outdoor experiment was carried out in the testing field, and the results prove the sensor can work properly in harsh environments and no creep is observed during the experiment.

A Passive Optical Fiber Anemometer for Wind Speed Measurement on High-Voltage Overhead Transmission Lines

Measurement of wind speed is an essential part of overhead transmission line monitoring. To overcome the drawbacks of the existing anemometer, such as the requirement on field power, the sensitivity to electromagnetic interference, and the unavailability of real-time measurement, a novel anemometer is developed on the basis of the fiber Bragg grating (FBG) sensing technique. In the anemometer, a beam with uniform strength was used to measure the force generated by the wind; two naked FBGs were symmetrically glued on the upper and lower surfaces of the beam to solve the problem of cross-sensitivity between strain and temperature of FBG sensing. Furthermore, the temperature effect on the zero output was investigated by putting the FBG anemometer into a temperature-controlled cabinet, and the experimental results indicated that the temperature effect on the zero output of the wind speed was less than ±5 pm (-10° C to 50 °C). The results from the wind tunnel experiment indicated that the measurement error of the anemometer was less than ±0.5 m/s.

Measurement of VFTO Based on the Transformer Bushing Sensor

Disconnector switching operations in large gas-insulated switchgear (GIS) systems may produce very fast transient overvoltages (VFTOs), causing high electric stress to other apparatuses in the substation, such as power transformers. This paper presents a VFTO measuring technique based on a transformer bushing sensor, which consists of the transformer bushing (C1) and a capacitor sensor (C2) installed at the test tap of transformer bushing. In order to solve the problem of the frequency limitation of the transformer bushing sensor for measuring VFTO, a convolution model on the square-wave response of the transformer bushing sensor is introduced to obtain the frequency response of the transformer bushing sensor, and a deconvolution model based on the incremental Wiener filter is applied to reconstruct the input transient voltage waveform at the tip of the bushing by using the output signals from the bushing sensor. A 110-kV transformer bushing sensor and a fast transient overvoltage source are built in our laboratory. The results from the laboratory indicate that a transient voltage can be measured correctly based on our technique with the 110-kV transformer bushing sensor. A 750-kV transformer bushing sensor is built in a 750-kV substation. The measuring results from the 750-kV substation by using our technique show that the peak value of the VFTO produced by the disconnector (AIS) switching off operations is about 775 kV, and the dominant oscillating frequencies of the VFTO are 3.5 MHz, 1.6 MHz, and 650 kHz.

Design of Fiber Bragg Grating load sensor used in ice monitoring on overhead transmission lines

Icing of high voltage transmission lines poses a great threat to the safety of the power grid. A Fiber Bragg Grating (FBG) load sensor is developed to monitor the load of the conductor. The major factor affecting the accuracy of the sensor is the structure of elastic element, and a novel closed-loop U structure is proposed to improve the accuracy. Finite Element Method (FEM) is introduced to investigate the strain distribution on the traditional structure and novel structure under axial load and eccentric load. The results of load experiment carried out in our laboratory indicate the sensor sensitivity is 0.0407pm/N and the sensor resolution is 24.57N.

Ice Monitoring on Overhead Transmission Lines with FBG Tension Sensor

Ice monitoring on the overhead transmission lines is very important to insure the power grid safe during the ice disaster. To solve the electromagnetic interference, a tension sensor based on Fiber Bragg Grating is developed to measure the tension of the power transmission line. The sensitivity of the sensor is 0.2286 pm/N calibrated with a test machine. The relative error of the load and sag, measured by the FBG sensing system, are smaller than 5% and 2% respectively based on our ice simulation system.

A novel Fiber Bragg Grating tension sensor for ground conductor

Ground conductor is easily broken when ice accumulates on it. Thus a novel Fiber Bragg Grating (FBG) sensor is proposed to measure the tension of the ground conductor to warning the danger. The factors affecting the sensitivity of the sensor are studied. The results of tension experiment indicate the sensitivity and resolution of the sensor are 0.2286pm/N and 2.18N respectively, and both of them can be easily altered by the equation proposed. The temperature effect on the measurement, which is caused by the crosstalk of FBG, is reduced by setting a zero-force FBG. The error of the sensor caused by temperature, evaluated by putting the sensor in an oven, is lower than 10 pm from −30 °C to 50 °C. An ice simulation platform is build in our laboratory, the results show the relative error of the simulated ice load calculated by the output of the sensor is lower than 5%.

Using Fiber Bragg Grating sensor on ice monitoring on electric power transmission lines, part I: the measurement of the temperature

A temperature measurement system and algorithm method based on Fiber Bragg Grating (FBG) sensors and Fabry-Perot Filter (FPF) is put forward. Three reference FBGs were used to eliminate the change of the FPF induced by the environment temperature and the nonlinearity of the FPF. Two FBG temperature sensors with different temperature sensitivity were used to measure the temperature, without the expensive standard light wave length component that provide absolute stable light wave length. Arithmetic was induced how to using the fixed wavelength difference of the reference FBGs to eliminate the influence of the environment temperature, and how to using the difference sensitivity of the temperature FBGs to get the absolute temperature of the transmission lines. Experiments with a glass of water were made to contrast the measurement results of this system with that of a mercury temperature meter whose precision is 0.1°C. The experiment results shown that this FBG system has precision bigger than 99.5%

Measurement And Analysis Of VFTO In a 750kV Substation

Disconnector operations in GIS may generate very fast transient overvoltage (VFTO), which is characterized by its high peak value, short rise time, and high frequencies. Mostly, researches on VFTO are focusing on the apparatus involving in the active circuit. However, VFTO may pass through open devices by electromagnetic coupling. To measure VFTO under this situation, lots of field experiments have been carried out in a 750 kV substation. VFTO is measured at the test tap of the high voltage reactor bushing, using the sensor we developed. In one of the experiments, the breaker is kept open, VFTO is generated by disconnector operations (in AIS) on one side of the breaker and measured on the other side. Results show that under this situation, VFTO could reach the peak values of about 55 kV and - 70 kV, the main oscillation frequencies are about 236 kHz, 535 kHz and 1.59 MHz. To verify this case further, computer simulation has also been carried out in the laboratory with the help of ATP. The results agree with each other well.

Ice monitoring system of transmission lines based on fiber bragg grating sensor

Ice monitoring on the overhead transmission lines is very important to insure the power grid safe during the ice disaster. However, the existing monitoring systems have some disadvantages such as sensitivity to electromagnetic interference, and short lifespan. In order to solve these problems, a novel on-line monitoring system based on Fiber Bragg Grating (FBG) sensing technique is developed. The temperature effect on the tension and angle measurement is reduced by setting temperature compensation FBG, and the effect is evaluated by putting the sensor in an oven. A long-term experiment is carried out outdoor to check the reliability of the monitoring system, the results indicate the system can work properly in harsh environment, no creep happened to the sensor, and the wind speed measured by the sensor in the system coincides with the speed provided by the meteorological bureau. The developed ice monitoring system is suitable for long-term ice monitoring.

Optical measurement of ice load on transmission lines

Traditional tension sensors used in ice monitoring on transmission lines are easily disturbed by the strong electromagnetic field. In this paper, a novel optical measuring system in the basis of Fiber Bragg Grating(FBG) sensing technology is proposed. The FBG tension sensor is designed based on shear beam, and its sensitivity is then analyzed. The results of tension experiment indicate the sensor sensitivity is 0.0495pm/N and the sensor resolution is 20.2N. In the end of this paper, algorithm of ice load using the date from only one sensor is discussed.