52results about How to "Address cross-sensitivity issues" patented technology

The invention discloses a fiber bragg grating (FBG) sensor based transformer fault gas monitoring system in the technical field of on-line monitoring system. The system comprises a gas sensor array, FGG demodulation equipment, a transformer fault monitoring center and the like. In the system, an FBG sensor is adopted, and the FBG sensor has strong anti-electromagnetic interference and is beneficial to application to environment with extremely severe electromagnetic environment; the sensor has high sensitivity and high resolution and can be used for simultaneously detecting all parts of the transformer on line, thereby the system maintenance cost is greatly reduced; and the system solves a series of problems of cross sensitivity among gases, slow oil-gas separation and balancing, short breathable film service life, and the like in the traditional fault monitoring method.

The invention discloses a Brillouin Optical Time Domain Reflectometry (BOTDR) temperature and strain rapid separation method in the icing monitoring of a smart grid. The optical fiber composite overhead ground wire (OPGW) cable in the power grid is used for sensing and monitoring to obtain Brillouin Abyss scattering spectrum. Select points within 3dB of the maximum value of the Brillouin scattering spectrum along the fiber path to perform quadratic polynomial fitting based on the least squares method. After fitting, the polynomial equation is obtained. After calculating the peak power and center frequency according to the polynomial coefficients, the obtained Power and frequency shift curves. According to the frequency shift curve and power curve, select the fiber splicing point, and recalibrate the temperature coefficient and gauge coefficient of Brillouin power. After the coefficient is corrected, the temperature and strain can be accurately separated.

The invention discloses a detection method suitable for a sensing device of optical fiber distribution type temperature and stress. The sensing device of the optical fiber distribution type temperature and stress mainly comprises a light source module (1), a frequency discriminator module (2), and a thermo tank module (3), which are all connected with one another by polarization-preserving fiber. The detection method of the invention is a direct detection method which is based on optical fiber Raman scattering used as a carrier wave of temperature information, brillouin scattering used as a carrier wave of stress, rayleigh scattering used for measuring the relative frequency of a outgoing laser beam to the frequency discriminator and Fabry-Perot etalon used for discriminating frequency and distributing sensing temperature and stress. The invention has the advantages of simple structure, fine stability, avoidance of outgoing power of the light source during coherent detection, and outgoing frequency of the light source. Instability of acoustic modulation or electro-optic modulation frequency is directly referred to measure errors and the direct detection technology of frequency discrimination is not sensitive to the frequency drift of the light source and the fluctuation of signal intensity.

The invention discloses a vibration monitoring system and a vibration monitoring method for divided conductors. The vibration monitoring system comprises a divided conductor vibration monitoring device (25), optical fiber (26), an optical fiber composite overhead ground wire (29), a fiber bragg grating demodulator (30) and a computer system (31). According to the vibration monitoring system and the vibration monitoring method, vibrations of the divided conductors of a power transmission line in three directions, especially the integral torsional vibration and the sub-conductor torsional vibration of a divided conductor beam are monitored, and the multipoint real-time monitoring can be carried out on the torsional rigidity of the power transmission line; and various types of divided conductors can be monitored through simple transformation, and the influence on the inherent property of the line is less. The defects that a field power supply is needed, the anti-electromagnetic interference capability is poor and the like as the torsional vibration of the conductors cannot be monitored, especially a system which can be used for implementing vibration monitoring of the divided conductors is absent and the self property of the line is easily influenced by installation of the traditional sensing system in the prior art are overcome, and convenience is provided for operation and maintenance of the line.

The invention discloses a side surface polished open-loop PCF-SPR sensor. The side surface polished open-loop PCF-SPR sensor comprises a fiber core and a cladding covered outside the fiber core, wherein the fiber core is eccentric with the cladding, and the cladding is provided with air holes which are arranged in the axial direction of the fiber core; the air holes comprises a first air hole, a plurality of second air holes and a plurality of third air holes, the first air hole is arranged at the center of the cross section of the optical fiber, the second air holes surround the first air hole to form an annular N-angle structure with a layer number of K, and the third air holes are symmetrically arranged on two sides of the fiber core to substitute the positions of second air holes; theside surface of an optical fiber is provided with a polishing plane, and the polishing plane is provided with an open loop; and the open loop is covered with a sensing membrane, and the open ring is used as a sensing channel. By adopting a way of combining the side surface polished optical-fiber end surface and the open loop, the SPR sensing layer is most closest to the fiber core, so that substances with a refractive index less than 1.3 such as liquid oxygen, liquid CO2, fluorine-containing organic matters can be detected sensitively at a high amplitude or high wavelength and can be sensed byvirtue of multiple channels, so that the application range of the existing PCF-SPR sensor can be enlarged.

The invention proposes a method for simultaneously measuring the magnetic field and temperature based on the magnetic fluid filling the photonic crystal microcavity. Two cascaded photonic crystal microcavities are formed by filling two different types of magnetic fluids in the air holes in two different regions of a photonic crystal waveguide plate, so that the output spectrum of the photonic crystal waveguide will appear in two independent resonance valleys (corresponding to two resonance wavelengths). As the external magnetic field or temperature changes, the refractive index of the two filled magnetic fluids will change to varying degrees, so that the two resonance wavelengths in the output spectrum of the photonic crystal waveguide will move, and the two resonance wavelengths will refract the magnetic fluid. Sensitivity to rate changes is inconsistent. Finally, the dual-wavelength matrix method is used to deduce the change of the external magnetic field and temperature according to the movement of the two resonance wavelengths, so as to realize the simultaneous measurement of the magnetic field and temperature. It can be calculated that the minimum detectable magnetic field change is 1.333Oe, and the minimum detectable temperature change is 0.301K.

The invention provides a rotating wheel vibration measurement method and a rotating wheel vibration measurement device based on fiber gratings. The rotating wheel vibration measurement method comprises the following steps of binding the fiber gratings with different central wavelengths with two sides of a rotating wheel; making the rotating wheel rotate in a constant speed, in rotation of the rotating wheel, transmitting a vibration signal which is generated by the rotating wheel to the fiber gratings, and generating strain signals by the fiber gratings; performing photoelectric conversion on the strain signals of the fiber gratings, and performing data acquisition; processing the acquired data and drawing a time-wavelength line chart in which the wavelength changes along with time, and obtaining a corresponding vibration characteristic of the rotating wheel; making the rotating wheel perform constant-speed rotation in different rotating speeds, performing data acquisition in different rotating speeds, drawing a rotating-speed-wavelength line chart in which the wavelength changes along with the rotating speed, and obtaining the corresponding vibration characteristic of the rotating wheel; making the rotating wheel perform constant-speed rotation in a certain rotating speed, performing data acquisition in different angles-of-attack, drawing an angle-of-attack-wavelength line chart in which the wavelength changes along with the angle-of-attack, and obtaining corresponding vibration characteristic of the rotating wheel.

The invention discloses a multi-parameter identification system and method of a tapered fiber, belongs to the field of fiber sensors, and mainly aims at solving the technical problems that a fiber sensor manufacturing technology is complex and the measuring accuracy is hard to ensure at present. The multi-parameter identification system comprises a signal collection system, a data preprocessing system and a data processing system; the data processing system comprises an output processing unit which includes a SVR (Support Vector Regression) model; and data is collected by the signal collection system, the collected data is processed by the data preprocessing system to form sample data, and the data processing system uses the sample data and a relation model, established by a support vector machine, between input and output, inputs a measured quantity to be measured to the model, and obtains a required output value. According to the invention, variation of the resonant wavelength between two different loss peaks of the tapered fiber is detected to measure temperature and strain of the same tapered fiber at the same time, the operation steps of detection is fewer, and the cost is reduced.