146 results about "Dielectric response" patented technology

The invention discloses an evaluation method for a paper oil insulation aging state through characteristic parameters based on time domain dielectric response. The evaluation method for the paper oil insulation aging state through the characteristic parameters based on the time domain dielectric response comprises the steps of measuring a polarization and depolarization current of a system, simulating an equivalent circuit of the polarization and depolarization current, calculating circuit parameters of an equivalent circuit model to obtain a depolarization current, smoothing the depolarization current and fitting the depolarization current to obtain depolarization power quantity, building a function relationship of aging time and characteristic parameters of the depolarization power quantity, integrating the relationship between the polymerization degree changing rule and the characteristic parameters of the depolarization power quantity through combining a first order dynamical model of a polymerization degree changing rule of mineral paper oil insulation acceleration thermal aging. By the utilization of the evaluation method for the paper oil insulation aging state through the characteristic parameters based on the time domain dielectric response, the operation is simple, sensitivity is high, and the evaluation method for the paper oil insulation aging state through the characteristic parameters based on the time domain dielectric response is suitable for the use of engineering.

The invention discloses a traction transformer layered oilpaper insulation dielectric response experiment system comprising a transformer oil tank, a layered insulation system disposed in an experiment box body, a connecting device (an oil pump, a plastic hose and multi-pipe joints) of the transformer oil tank and the experiment box body, a dielectric response tester, and a control and data acquisition system. The experiment system of the invention can be used for simulating non-uniform heat aging in an actual traction transformer oilpaper insulation system and researching the dielectric response characteristic of the oilpaper insulation of non-uniform heat aging, and can help to research remaining life evaluation of the oilpaper insulation with non-uniform heat aging distribution.

The invention provides a bushing oil-impregnated paper insulating frequency domain dielectric spectrum experiment system and a bushing oil-impregnated paper insulating frequency domain dielectric spectrum experiment method at a non-uniform temperature. The system comprises an experiment box, an oil-impregnated paper insulating temperature control system, an insulated oil box with a heating device, a 12V DC power supply, a connecting device between the experiment box and the insulated oil box, an acquiring and control system, a dielectric response tester, a switch control system and a computer. The method comprises the steps of starting the acquiring and control system so that insulating oil is circulated in an oil path, thereby keeping a constant oil temperature of the insulating oil in the experiment box; switching on the 12V DC power supply for heating to a Curie temperature; starting the dielectric response tester, performing frequency domain dielectric spectrum testing on the bushing oil-impregnated paper insulation at the non-uniform temperature by means of the switch control system, receiving data uploaded from the dielectric response tester by a computer, and performing corresponding storage and analysis. The system and the method provided by the invention can perform frequency domain dielectric spectrum testing on the bushing oil-impregnated paper at the non-uniform temperature, thereby researching the dielectric characteristic of the bushing oil-impregnated paper insulation at an actual working condition temperature.

The invention discloses a cable insulation aging degree testing method and apparatus based on impact voltages, and belongs to the electric cable detection field. According to the method, a frequency domain dielectric spectrum of a cable is obtained by obtaining voltage and current wave forms of the to-be-tested cable under the effect of different impact voltages, and the insulating aging degree ofthe cable is evaluated by obtaining dielectric response situations at the 0-10kHz frequency band in the frequency domain dielectric spectrum. Compared with a conventional dielectric response measuring method, the method has the advantages that a corresponding impact current amplitude is high, the impact currents are easy to measure and is not liable to be interfered by noise, and the impact voltage and current measuring technology is more mature. More information showing insulation aging of the cable can be obtained, and dielectric loss situations at different frequencies can be used for analysis and research. Therefore, the dielectric response under the effect of impact voltages can evaluate the aging degree of the cable more effectively.

A ceramic dielectric composition suitable for preparing capacitors for use in high-temperature service conditions is disclosed. The ceramic material and capacitors made from it exhibit unique and heretofore unrealizable properties including low variation in capacitance with voltage up to high fields, low variation in capacitance with temperature over a broad temperature range, retained high permittivity at temperatures up to 200° C. and beyond, low loss, low field-induced strain and adequate capacitance to retain performance at very low service temperatures. The material is based on sodium bismuth titanate (NBT) with selected additions of substituents and dopants to broaden and flatten its dielectric response, lower loss, lower strain, lower voltage coefficient and increase resistivity.

The invention discloses a device for measuring subsurface structure characteristic and micro-area wideband dielectric property, and the device comprises an electrostatic force microscope which comprises a conductive miniature cantilever probe comprising a conductive probe part and a miniature cantilever probe part, wherein a probe carries out the first scanning of a to-be-measured sample in a touch scanning mode. The device also comprises a phase-locking amplifier which is used for receiving a reference frequency signal and a real-time signal generated in the first scanning process, and generating a first phase signal according to the reference frequency signal and the real-time signal. After the first scanning, the probe carries out the second scanning of the to-be-measured sample along the scanning trace of the first scanning in a mode of lifted scanning. The phase-locking amplifier also generates a second phase signal according to the reference frequency signal and a real-time signal generated in the second scanning process. The device also comprises a signal source which enables a modulation voltage signal to be applied to the conductive probe part in the second scanning process, and to be outputted to an external phase-locking amplifier. The device also comprises the external phase-locking amplifier which is used for receiving the modulation voltage signal and the second phase signal, and obtaining a dielectric response signal and a dielectric loss angle signal according to the modulation voltage signal and the second phase signal.

The invention discloses a method for testing transformer oil paper insulation frequency domain dielectric response and a device thereof. The device comprises a variable frequency signal generator (1), a signal conditioning module (3), a signal acquisition module (8) and a processing module (11). The signal output end of the variable frequency signal generator (1) is connected to the input end of a tested transformer (2). The output end of the tested transformer (2) is connected to the receiving end of the signal conditioning module (3) and the receiving end of the signal acquisition module (8). The method and the device have the advantages that the operation is simple, the measurement precision is high, the anti-interference ability is strong, the measurement result information is rich, the measurement of transformer oil paper insulation frequency domain dielectric response can be completed in a complex field environment, the cost is low, the method and the device can be widely popularized and applied in a domestic power system, the transformer oil paper insulation aging state assessment and fault diagnosis are improved further, and the method and the device have an important meaning to the reliable operation of the power system.

The invention discloses a quantitative evaluation method for the internal insulation aging degree of an oil-immersed power transformer, and belongs to the field of oil-paper insulation aging state evaluation. A frequency domain dielectric characteristic basic data curve of an oil-immersed paperboard without moisture and dielectric loss factor basic data curves of the oil-immersed paperboard with different aging degrees are obtained, and the water content, the polymerization degree and the conductivity of the oil-paper are quantitatively evaluated in different frequency bands based on the frequency domain dielectric response curve; accurate assessment of the insulation state of the aged transformer oil paper through the frequency domain dielectric response test of the transformer oil paperinsulation is realized, the time of on-site transformer insulation aging assessment can be effectively reduced, and the method has important significance for assessment of the insulation aging state and the polymerization degree of the oil paper insulation equipment on site.

The invention discloses an oil paper insulation water content evaluation method based on polarization loss and electric conduction loss. The method comprises the following steps of 1, performing frequency domain dielectric spectrum test preparation; 2, solving relevant parameters of an oil soaking insulation paper board expansion Debye model conforming to the frequency domain dielectric spectrum matching requirements, so that the spectrum unscrambling of the oil soaking insulation paper board frequency domain dielectric spectrum test is completed; 3, calculating the electric conduction loss and the polarization loss of the oil soaking insulation paper board on the basis of the complex capacity test spectrum unscrambling result of the frequency domain dielectric spectrum of the oil soaking insulation paper board; 4, respectively making frequency curves of the electric conduction loss and polarization loss according to the electric conduction loss and the polarization loss, obtaining the intersecting point frequency of the two curves, and calculating the water content of the oil soaking insulation paper board through the intersecting point frequency of the frequency curves of the electric conduction loss and polarization loss. The problems that the reliability of an oil paper insulation water content evaluation method based on the physicochemical properties in the prior art is insufficient, and the measurement frequency band of the time domain dielectric response technology is narrow, the interference by the environment is obvious, and the like are solved.

The invention relates to a method for evaluating the aging state of an oil-paper insulation system of an oil-immersed transformer, and belongs to the field of power equipment evaluation, and the method comprises the steps: S1, carrying out the frequency domain dielectric response test of oil-immersed insulation paper boards with different moisture contents and aging states; S2, extracting a dielectric modulus characteristic quantity representing the synergistic interaction influence of the moisture and the aging product; and S3, constructing an association relationship between the polymerization degree of the oil-immersed insulating paper board and the imaginary part integral value of the dielectric modulus under the influence of synergistic interaction of moisture and the aging product. According to the method, the aging state of the oil-paper insulation system of the oil-immersed power transformer can be evaluated by fusing the synergistic effect of the moisture and the aging product; the moisture content can be in the range of 0.5%-5%, which is more in line with the actual operation of the on-site oil-immersed transformer, and makes up the technical problem that a traditional method only considers the single factor (moisture or aging) to evaluate the aging state of the oil-paper insulation system inaccurately.

The invention relates to a transformer insulating board dampness quantitative evaluation method based on dielectric response characteristic. The method has the main technical characteristic that taking oil on a detected transformer, and sending an oil sample test object to laboratory test; performing on-site dielectric spectral measurement of an transformer; calculating a dielectric constant of the transformer under specific frequency, performing dielectric spectral measurement on an insulation paper test object; establishing a XY model; calculating the integral dielectric spectrum of the transformer under different water contents; fitting a relation of the dielectric constant of the transformer and the water content of an insulating board under specific frequency; and calculating the water content of the insulating board of the transformer. The method has the advantages of reasonable design, convenient measurement and calculating, and accurate result, realizes a quantitative evaluation function of the dampness condition of the insulating board of the transformer under condition of a sampling, is helpful for accurately grasping the running state of the transformer for operation andmaintenance staff, test staff, and maintenance staff, and realizes the accurate analysis and equipment management functions.

The invention discloses a method for a rapid dielectric response test based on time domain and frequency domain combination. The method includes obtaining a dielectric frequency spectrum with frequency of a product to be tested being larger than a set frequency threshold value; adopting a three-electrode method to measure polarization and depolarization current curves of the product to be tested;calculating conductivity of the product to be tested according to popularization and depolarization currents; calculating to obtain a dielectric frequency spectrum with frequency of the product to betested being lower than the set frequency threshold value according to the depolarization currents and conductivity; and splicing the dielectric spectrum with frequency of the product to be tested being larger than the set frequency threshold value and the dielectric spectrum with frequency being lower than the set frequency threshold value to obtain a dielectric spectrum of the product to be tested. The method provided by the invention combines advantages of PDC and FDS, and compared with a traditional FDS measuring method, 80% of time can be saved, and an effect of accuracy is greatly improved.

The invention discloses a transformer dry casing defect simulation and performance state monitoring system and method. Two ends of a conducting rod are connected with a transparent organic glass cavity through sealing rings, two ends, extending out of the transparent organic glass cavity, of the conducting rod are respectively connected with a first grading ring and a second grading ring, one endof the conducting rod is connected to a voltage source output end of the voltage source module through the first grading ring and a corresponding connector lug, a test signal interface of a dielectricresponse test module is connected with one end of a conducting rod through the first grading ring and the corresponding connector lug, a monitoring signal interface of a discharge characteristic monitoring module is connected with the other end of the conducting rod through a second grading ring and a corresponding connector lug, and the two ends of the conducting rod are connected to two poles of a current source module through the first grading ring and the corresponding connector lug, and the second grading ring and the corresponding connector lug respectively; according to the invention,accurate detection and simulation of casing defects can be realized.

The invention discloses an oilpaper insulation system relative dielectric constant test method under low-frequency sine excitation. An actually measured parameter temperature is obtained through a test, a ratio of the total thickness of a paper cylinder to a main insulation thickness between high and low-voltage windings and a ratio of the total width of a stay to main insulation average perimeter between the high and low-voltage winding are obtained through testing, then the tested data is substituted into a relative dielectric constant expression of an oilpaper insulation system under the low-frequency sine excitation, and finally, a relative dielectric constant of a transformer oil gap under the low-frequency sine excitation is obtained. According to the method, on the basis that the relative dielectric constant of the oilpaper insulation system under the low-frequency sine excitation is effectively calculated, the problem of long time consumed for measuring dielectric parameters of the oilpaper insulation system under the low-frequency sine excitation by use of an instrument can also be solved through a valve calculation method, and the application efficiency of a frequency domain dielectric response method in actual engineering is improved.

The invention relates to a thermal ageing experiment apparatus for simulating different oil flow velocity and high and low temperature impact of a transformer. The apparatus comprises a transformer oil tank, a layered insulation system placed in an experiment box body, a connecting device (comprising an oil pump, a plastic flexible pipe and a multi-way tube joint) for connecting the transformer oil tank with the experiment box body, a dielectric response tester and a control and data acquisition system. The experiment apparatus can simulate non-uniform thermal ageing of a practical traction transformer oil paper insulation system to research the dielectric response characteristic of the non-uniformly-thermal-aged oil paper insulation, so assessment of the residual life of the oil paper insulation with the non-uniform ageing distribution characteristic is facilitated.

The invention discloses a micro-current measuring circuit for dielectric response tests; the micro-current measuring circuit comprises a logarithm operation unit, a linear optical coupler unit, an index operation unit, and a signal secondary amplification unit connected in sequence; the logarithm operation unit comprises an ultra low bias current amplifier and a negative feedback element; the linear optical coupler unit comprises a linear optical coupler chip and a negative feedback circuit; the index operation unit comprises a high speed operation amplifier and a photosensitive diode; the micro-current measuring circuit has no feedback resistor, so the measuring result cannot be affected by a resistance temperature coefficient, thus providing high temperature drift influence inhibition ability, and the temperature coefficient can reach 100ppm/C.

Embodiments of the subject method and apparatus relate to a sequence of noncontact Corona-Kelvin Metrology that allows the determination and monitoring of interface properties in dielectric/wide band gap semiconductor structures. The technique involves the incremental application of precise and measured quantities of corona charge, Q_C, onto the dielectric surface followed by determination of the contact potential difference, V_CPD, as the material structure response. The V-Q characteristics obtained are used to extract the surface barrier, V_SB, response related to the applied corona charge. An intersection of the V_CPD-Q_C characteristic obtained in the dark with the V_OX-Q_C characteristic representing the dielectric response is determined. The specific V_SB-Q_C dependence surrounding the reference V_FB value is obtained and the dielectric interface trap density and its spectrum is determined. A method and apparatus to quantify and separate trapped charge components is provided.

The invention belongs to the technical field of solid dielectric medium application and particularly relates to a method for measuring the nucleation reversible electric domain polarization intensity of a ferroelectric film. After voltages with different pulse widths are applied from the electric domain polarization direction of the pre-polarized ferroelectric film to the anti-parallel direction of applied voltage, ferroelectric capacitor discharge charge surface densities and reversal electric domain polarization intensities of the ferroelectric film are measured when different ferroelectric capacitor voltages are applied; after voltages with different pulse widths are applied from the electric domain polarization direction of the pre-polarized ferroelectric film to the parallel direction of applied voltage, ferroelectric capacitor discharge charge surface densities are measured when different ferroelectric capacitor voltages are applied; finally, the nucleation reversible electric domain polarization intensity of the ferroelectric film can be calculated. The method can be adaptable to various conditions, is high in measurement accuracy, brings convenience to a user for looking into the dynamics mechanism of the nucleation electric domain growth motion of the ferroelectric film and can be applied to novel devices such as a device with ultrahigh dielectric response performance.

The invention relates to a small-size watermelon ripeness detection method based on a dielectric frequency spectrum. The small-size watermelon ripeness detection method comprises the following steps of: placing a watermelon to be detected into a detection device formed by three sets of electrodes which are tightly stuck to the surface of the watermelon; applying alternating electromotive force among the electrodes; measuring a dielectric response signal of the watermelon to the alternating electromotive force; carrying out data processing on a dielectric frequency spectrum signal; judging the ripeness of the watermelon through a clustering analysis; meanwhile, collecting temperature information in the detecting process and carrying out temperature compensation in the data analyzing process. According to the method disclosed by the invention, dielectric spectrums with different frequencies are used for realizing the nondestructive detection, and the problem that the measurement is inaccurate, caused by only using a single frequency, is overcome; meanwhile, the dielectric spectrum scanning is carried out at a plurality of angles so that the measuring error caused by individual difference is reduced; the electromagnetic interference is eliminated and the high-frequency interference to a collection circuit by an exciting circuit is eliminated; a temperature compensation algorithm is added and the influence on the measurement accuracy by temperature variation is eliminated.

The present invention relates to a transformer insulating cardboard aging quantitative evaluation method based on dielectric response features. The main technical features of the method comprise the steps of: performing oil extraction of a tested transformer, and transmitting oil sample test objects to a lab for test; performing field transformer dielectric spectrum measurement; calculating a dielectric loss factor of the transformer under a special frequency; measuring dielectric spectrums of different insulating paper test objects through a frequency domain response dielectric spectrum testmethod; establishing an XY model, and calculating the whole dielectric spectrum of transformers with different aging degrees; fitting a relation of the transformer dielectric loss factors under the special frequency and the insulating cardboard aging degrees; and calculating the insulating cardboard aging degree. The method provided by the invention is reasonable in design, convenient to measure and calculate and accurate in result, achieve the quantitative evaluation function of the transformer insulating cardboard aging condition in a condition without hoisting cover sampling, is helpful formaintenance, test and repairing personnel to accurately grasp the operation state of the transformer and achieves accurate analysis and device management functions.

The invention relates to an experiment model device of an oiled-paper condenser bushing. The portions, located at the top end of an upper insulator and the tail end of a lower insulator, of a conducting rod are each sleeved with a pressing ring and a nut; when the nuts at the upper end and the lower end are fastened, a sealed cavity can be formed by a gap among a condenser core, the upper insulator, a flange and the lower insulator; a sensor installation base for installing a sensor is arranged on the cylindrical side wall of the flange, and a vacuumizing valve port and an oil injection valve port which are communicated with the cavity are formed in a step of the flange in a spaced mode; an oil window communicated with the cavity is further formed in the cylindrical side wall of the flange. According to the experiment model device, the size of the bushing is reduced compared with a true bushing, main structures of the true bushing are provided, the assemblies are made of materials completely the same as materials of the true bushing, and the experiment model device can be used for performing multiple dielectric response experiments of the condenser core under different conditions such as wetting and aging.

The invention relates to the technical field of high voltage and insulation, and particularly discloses a method for establishing a frequency domain dielectric response characteristic fingerprint database based on deep fitting, which comprises the following steps: acquiring a frequency domain dielectric spectrum of transformer solid insulation; respectively extracting frequency bands of frequencydomain dielectric response characteristics sensitive to transformer solid insulation aging and damp states; respectively carrying out integral operation on the extracted different frequency bands to obtain integral values of the FDS curve; obtaining a dielectric response characteristic fingerprint according to the integral value; enabling the dielectric response characteristic fingerprints to be in one-to-one correspondence with the corresponding insulation states, placing the dielectric response characteristic fingerprints and the corresponding insulation states in the same spatial dimensionto obtain a dielectric response characteristic fingerprint change rule, and performing deep fitting to establish a universal model capable of calculating the dielectric response characteristic fingerprints corresponding to any insulation state; and establishing a frequency domain dielectric response characteristic fingerprint database by utilizing the universal model. According to the method, thefrequency domain dielectric response characteristic fingerprint can be calculated by utilizing the model on the premise of not preparing any sample.

The invention discloses a transformer bushing dielectric loss live detection method and system based on transient voltage disturbance. The method comprises the steps of collecting and obtaining electromagnetic transient voltage signals generated by a system connected with a to-be-tested transformer; processing the collected electromagnetic transient voltage signals and obtaining effective electromagnetic transient voltage signal data in a preset frequency range; collecting and obtaining a transformer bushing leakage current when transient voltage disturbance occurs; and computing bushing insulation dissipation factors under different frequencies through utilization of the obtained effective electromagnetic transient voltage signal data and leakage current, thereby finishing bushing dielectric loss live detection of the to-be-tested transformer. According to the method and the system, the transient voltage signals at a position of a guide rod of a transformer bushing inlet is collectedand the transient voltage signals are taken as excitation sources of a transformer bushing insulation dielectric response test, so the live detection of an insulation state of a bushing can be realized, and manpower and time cost when conventional uncharged detection of the insulation state is carried out can be reduced.

The invention belongs to the technical field of performance test of solid dielectric medium, in particular to a method for measuring the differential capacitance of a ferroelectric film by rapid voltage sweep. Fully considering the contribution of different microcosmic ferroelectric domains in the film to a macroscopical capacitance value under the action of an external voltage, the method adoptsthe steps as following: remaining enough relaxation time after presetting impulse so that the pinning effect of charged charges on the microcosmic electric domains is reduced to the minimum; rapidly sweeping through the following impulse voltage with any amplitude, charging a capacitor, and enabling the capacitor of a ferroelectric film to generate corresponding discharging current through slightchange of the charging voltage; and calculating the discharging charges through an oscilloscope connected with a sample, thereby obtaining the corresponding differential capacitance. The invention solves the problem that a memercial electrical bridge cannot rapidly carry out voltage sweep, and provides an effectively measure for measuring the high-frequency response of the capacitance of the ferroelectric film and searching the contribution of microdefect movement to the dielectric response aspect.