CN114720516A - Method and device for evaluating aging degree of transformer oil and sensing system - Google Patents
Method and device for evaluating aging degree of transformer oil and sensing system Download PDFInfo
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Abstract
The embodiment of the invention provides a method, a device and a sensing system for evaluating the aging degree of transformer oil, wherein the method comprises the following steps: recording a polarization curve and a non-polarization curve of the transformer oil under direct-current voltage; collecting at least one voltage effective value and at least one current effective value of the transformer oil under an alternating current excitation signal; calculating the first conductivity of the transformer oil by combining the capacitance of the conductive electrodes at the two ends of the transformer oil; calculating at least one second conductivity based on the voltage and current effective values; and acquiring the infrared light absorption rate of each aging product, and calculating the aging index of the transformer oil by combining the first conductivity and at least one second conductivity to obtain the aging degree evaluation result of the transformer oil. Compared with the prior art, the method can be used for testing on line, and the influence of impurities on the conductivity of the transformer oil is considered by acquiring at least one conductivity of the transformer oil under the direct-current voltage and the alternating-current voltage, so that the accuracy and the real-time performance of the test are improved.
Description
Technical Field
The invention relates to the field of transformer oil, in particular to a method and a device for evaluating the aging degree of transformer oil and a sensing system.
Background
The transformer oil is mineral insulating oil refined based on petroleum products, and the main components of the transformer oil comprise alkane, cyclane, aromatic hydrocarbon and the like. Transformer oil is the main liquid insulating medium used for insulation, cooling and arc extinction in electrical equipment. With the lapse of equipment running time, the transformer oil can have the phenomenon such as oxidation aging, generate ageing products such as free radical, alcohol, aldehyde and ketone, seriously influence the insulating properties of transformer oil.
At present, the aging degree evaluation method of transformer oil mainly comprises the steps of taking out the transformer oil, placing the transformer oil in a constant-temperature drying oven, heating the transformer oil to a temperature 10 ℃ lower than the flash point of the transformer oil, and measuring various components and the content of the components through chromatography and infrared spectroscopy. The method cannot perform real-time test when the equipment runs on line, so that the aging degree of the transformer oil cannot be reflected timely. The existing online tester obtains single information, can only test under the condition of single frequency conductivity, and is difficult to accurately judge the aging degree of the transformer oil.
Disclosure of Invention
The invention provides a method and a device for evaluating the aging degree of transformer oil and a sensing system, and a more accurate aging degree evaluation result is obtained by acquiring the conductivity of the transformer oil under different voltage conditions.
In order to solve the technical problem, an embodiment of the present invention provides a method for evaluating an aging degree of transformer oil, including:
respectively collecting polarized current and non-polarized current of the transformer oil under direct current voltage in real time, and recording a polarization curve and a non-polarization curve of the transformer oil under the direct current voltage according to the collected polarized current and the non-polarized current; wherein the polarization curve is a curve of the polarization current of the transformer oil along with the change of time; the non-polarization curve is a curve of the non-polarization current of the transformer oil along with the change of time;
respectively acquiring not less than one voltage effective value and not less than one current effective value of the transformer oil under each alternating current excitation signal in real time; each alternating current excitation signal corresponds to the type of an aging product;
calculating first conductivity of the transformer oil according to the polarization curve, the non-polarization curve and the direct-current voltage by combining capacitance of conductive electrodes at two ends of the transformer oil; respectively calculating not less than one second conductivity of the transformer oil according to the not less than one voltage effective value and the not less than one current effective value;
acquiring the infrared light absorption rate of each aging product, and calculating the aging index of the transformer oil by combining the first conductivity and the at least one second conductivity to obtain the aging degree evaluation result of the transformer oil; wherein each infrared light absorption rate corresponds to the characteristic frequency of each aging product. Compared with the prior art, the on-line evaluation method is provided, the influence of impurities on the conductivity of the transformer oil is considered by acquiring at least one conductivity of the transformer oil under the direct-current voltage and the alternating-current voltage, and the accuracy and the real-time performance of on-line detection are improved.
As a preferred scheme, the obtaining of the infrared light absorption rate of each aging product, and combining the first conductivity and the at least one second conductivity to calculate the aging index of the transformer oil specifically include:
obtaining the infrared absorptivity x of the aged producti1、xi2、…、ximIn combination with said first electrical conductivity σi1Said at least one second electrical conductivity σi2、σi3、σi4And σi5Performing multiple linear regression analysis according to the following formula to obtain the aging index y of the transformer oil in the ith testi：
yi＝b0+b1σi1+b2σi2+…+b5σi5+c1xi1+c2xi2+c3xi3+…+cmxim+Di；
Wherein, b0Is intercept, DiFor residual, the number of correction set samples is n, the number of spectra is m, and n > m + 5. By implementing the embodiment of the application, the aging degree of the transformer oil is effectively evaluated by combining the conductivity of the transformer oil under direct-current voltage and alternating-current voltage and the analysis of absorption spectra of different aging products, and the aging index is obtained.
As a preferred scheme, the calculating, according to the polarization curve, the non-polarization curve and the direct-current voltage, and by combining capacitances of conductive electrodes at two ends of the transformer oil, a first conductivity of the transformer oil is respectively calculated, specifically:
obtaining the polarization curve ip(t) the non-polarization curve id(t) and the DC voltage U0Calculating a first electrical conductivity σ of the transformer oil according to:
wherein, C0Capacitance of the conductive electrodes at both ends of the transformer oil, epsilon0Is the dielectric constant of the transformer oil.
Correspondingly, the embodiment of the invention also provides an evaluation device of the aging degree of the transformer oil, which comprises a first acquisition module, a second acquisition module, a conductivity acquisition module and an aging evaluation module; wherein the content of the first and second substances,
the first acquisition module is used for acquiring the polarized current and the non-polarized current of the transformer oil under the direct current voltage in real time respectively, and recording the polarized curve and the non-polarized curve of the transformer oil under the direct current voltage according to the acquired polarized current and the non-polarized current; wherein the polarization curve is a curve of the polarization current of the transformer oil along with the change of time; the non-polarization curve is a curve of the non-polarization current of the transformer oil along with the change of time;
the second acquisition module is used for respectively acquiring not less than one voltage effective value and not less than one current effective value of the transformer oil under each alternating current excitation signal in real time; each alternating current excitation signal corresponds to the type of an aging product;
the conductivity acquisition module is used for calculating first conductivity of the transformer oil according to the polarization curve, the non-polarization curve and the direct current voltage by combining the capacitance of the conductive electrodes at two ends of the transformer oil; respectively calculating not less than one second conductivity of the transformer oil according to the not less than one voltage effective value and the not less than one current effective value;
the aging evaluation module is used for acquiring the infrared light absorption rate of each aging product, and calculating the aging index of the transformer oil by combining the first conductivity and the at least one second conductivity to obtain the aging degree evaluation result of the transformer oil; and the infrared light absorptivity corresponds to the characteristic frequency of each aging product one by one.
As a preferred scheme, the aging evaluation module obtains an infrared light absorption rate of each aging product, and calculates an aging index of the transformer oil by combining the first conductivity and the at least one second conductivity, specifically:
the aging evaluation module acquires the infrared absorptivity x of the aging producti1、xi2、…、ximIn combination with said first electrical conductivity σi1Said at least one second electrical conductivity σi2、σi3、σi4And σi5Performing multiple linear regression analysis according to the following formula to obtain the aging index y of the transformer oil in the ith testi：
yi＝b0+b1σi1+b2σi2+…+b5σi5+c1xi1+c2xi2+c3xi3+…+cmxim+Di；
Wherein, b0Is intercept, DiFor residual, the number of correction set samples is n, the number of spectra is m, and n > m + 5.
As a preferred scheme, the conductivity obtaining module calculates the first conductivity of the transformer oil according to the polarization curve, the non-polarization curve and the dc voltage by combining the capacitances of the conductive electrodes at the two ends of the transformer oil, specifically:
the conductivity acquisition module acquires the polarization curve ip(t) the non-polarization curve id(t) and the DC voltage U0Calculating a first electrical conductivity σ of the transformer oil according to:
wherein, C0Capacitance of the conductive electrodes at both ends of the transformer oil, epsilon0Is the dielectric constant of the transformer oil.
Correspondingly, the embodiment of the invention also provides a sensing system for the aging degree of the transformer oil, wherein the sensing system comprises a computer and an infrared composite sensor;
the infrared composite sensor comprises a conductance cell and an infrared absorption cell; the first end of the conductivity cell is connected with one output end of the transformer to be tested; the second end of the conductivity cell is connected with the first end of the infrared absorption cell, and the second end of the infrared absorption cell is connected with one input end of the transformer to be tested;
two opposite planes of the conductivity cell are provided with conductivity electrodes for measuring the conductivity of the transformer oil;
the infrared absorption cell is used for measuring the infrared light absorption rate of each aging product of the transformer oil under the irradiation of infrared incident light; the infrared light absorptivity corresponds to the characteristic frequency of each aging product one by one;
the computer is used for executing the method for evaluating the aging degree of the transformer oil. Implement this application embodiment, transformer oil flows in from the first end of conductance pond, flows out from the second end of infrared absorption pond, realizes online and real-time detection to transformer oil among the transformer operation process, need not to take out transformer oil from the transformer, has improved the convenience of detecting.
Preferably, the conductive electrode is a bright platinum electrode. By implementing the embodiment of the application, the bright platinum electrode is adopted, the adsorption of trace moisture by the electrode is prevented, the influence of capacitance change on the conductivity is avoided, and the error of the conductivity test is reduced.
As a preferred scheme, an electromagnetic shielding box is arranged outside the conductivity cell. By implementing the embodiment of the application, the influence of an external electromagnetic field on the test result is eliminated through the electromagnetic shielding box, and the accuracy of the test result is improved.
As a preferred scheme, sapphire windows are arranged at the incident position and the emergent position of infrared incident light of the infrared absorption pool; and a plurality of layers of silica gel gaskets are arranged between the sapphire windows. By implementing the embodiment of the application, the sapphire window is adopted, so that the erosion of water in the transformer oil sample is avoided, and the service life of the infrared absorption cell is prolonged; the size of infrared absorption pond is changed to the silica gel packing ring between the accessible regulation sapphire window, and then changes the light path length of infrared incident light in infrared absorption pond to the concentration range of adaptation ageing product improves the accuracy of measuring.
Drawings
FIG. 1: the invention provides a flow schematic diagram of an embodiment of a method for evaluating the aging degree of transformer oil.
FIG. 2: the invention provides a schematic structural diagram of an embodiment of a device for evaluating the aging degree of transformer oil.
FIG. 3: the invention provides a schematic structural diagram of an embodiment of an infrared composite sensor.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that, in the prior art, accurate online judgment on the aging degree of the transformer oil cannot be performed. The conductivity of the pure transformer oil is 5 xl 0 under the environment of 80 DEG C-14S/m, and a normal mineral oil containing impurities has a conductivity of 10-9And (5) S/m. The prior art generally uses a megger or an online conductivity meter, but because the conductivity meter adopts a fixed and single frequency to test, the judgment basis of the conductivity or the aging degree obtained by the conductivity meter is relatively single, and a reliable result is difficult to give.
The first embodiment is as follows:
referring to fig. 1, fig. 1 is a method for evaluating the aging degree of transformer oil according to an embodiment of the present invention, including steps S1 to S4; wherein the content of the first and second substances,
step S1, collecting polarized current and non-polarized current of the transformer oil under direct current voltage respectively in real time, and recording a polarization curve and a non-polarization curve of the transformer oil under the direct current voltage according to the collected polarized current and the non-polarized current; wherein the polarization curve is a curve of the polarization current of the transformer oil along with the change of time; the non-polarization curve is a curve of the non-polarization current of the transformer oil along with time.
In this embodiment, a DC voltage U is applied to the two end conductive electrodes0And collecting the polarized current and the non-polarized current of the transformer oil at the moment in real time. According to the polarization electricity over timeThe direct current U of the transformer oil can be obtained by current and non-polarized current0Polarization curve i ofp(t) and the non-polarization curve id(t)。
Step S2, respectively collecting not less than one voltage effective value and not less than one current effective value of the transformer oil under each alternating current excitation signal in real time; wherein each ac excitation signal corresponds to a category of aging products.
In the embodiment, according to the types of aging products, including but not limited to alcohol, aldehyde, ketone, carboxylic acid and the like, the frequency and amplitude of the alternating current excitation signal are sequentially changed, and not less than one voltage effective value and not less than one current effective value of the transformer oil are acquired in real time.
Step S3, calculating a first conductivity of the transformer oil according to the polarization curve, the non-polarization curve and the direct current voltage by combining the capacitance of the conductive electrodes at two ends of the transformer oil; and respectively calculating to obtain not less than one second conductivity of the transformer oil according to the not less than one voltage effective value and the not less than one current effective value.
In this embodiment, the polarization curve i is obtainedp(t) the non-polarization curve id(t) and the DC voltage U0Calculating a first electrical conductivity σ of the transformer oil according to:
wherein, C0Capacitance of the conductive electrodes at both ends of the transformer oil, epsilon0Is the dielectric constant of the transformer oil.
The second conductivity is the ratio of the effective value of the current I and the effective value of the voltage, and is used as a test signal. In the present embodiment, a total of four second conductivities σ are obtainedi2、σi3、σi4And σi5。
Step S4, acquiring the infrared light absorptivity of each aging product, and calculating the aging index of the transformer oil by combining the first conductivity and the at least one second conductivity to obtain the aging degree evaluation result of the transformer oil; wherein each infrared light absorption rate corresponds to the characteristic frequency of each aging product.
In this example, the number of samples of the calibration set in the infrared spectroscopic analysis is n, and the characteristic frequency λ of the aged product is selected and obtained1、λ2、…、λmInfrared absorption rate x in one-to-one correspondence with the samei1、xi2、…、xim. Combining said first conductivity σi1Said at least one second electrical conductivity σi2、σi3、σi4And σi5Performing multiple linear regression analysis according to the following formula to obtain the aging index y of the transformer oil in the ith testi：
yi＝b0+b1σi1+b2σi2+…+b5σi5+c1xi1+c2xi2+c3xi3+…+cmXim+Di；
Wherein, b0Is intercept, DiFor residual, the number of correction set samples is n, the number of spectra is m, and n > m + 5. The aging index yi can accurately evaluate the aging degree of the transformer oil. The method combines the conductivity of the transformer oil under direct current voltage and alternating current excitation signals, and can effectively evaluate the aging degree of the transformer oil through analysis of absorption spectra of different aging products.
Correspondingly, referring to fig. 2, an embodiment of the present invention further provides an apparatus for evaluating the aging degree of transformer oil, including a first acquisition module 101, a second acquisition module 102, a conductivity acquisition module 103, and an aging evaluation module 104; wherein the content of the first and second substances,
the first acquisition module 101 is used for acquiring polarized current and non-polarized current of the transformer oil under direct current voltage in real time respectively, and recording a polarization curve and a non-polarization curve of the transformer oil under the direct current voltage according to the acquired polarized current and the non-polarized current; wherein the polarization curve is a curve of the polarization current of the transformer oil along with the change of time; the non-polarization curve is a curve of the non-polarization current of the transformer oil along with the change of time;
the second acquisition module 102 is configured to acquire at least one voltage effective value and at least one current effective value of the transformer oil under each ac excitation signal in real time; wherein each alternating current excitation signal corresponds to a type of aging product;
the conductivity obtaining module 103 is configured to calculate a first conductivity of the transformer oil according to the polarization curve, the non-polarization curve and the dc voltage, in combination with capacitances of conductive electrodes at two ends of the transformer oil; respectively calculating at least one second conductivity of the transformer oil according to the at least one voltage effective value and the at least one current effective value;
the aging evaluation module 104 is configured to obtain an infrared light absorption rate of each aging product, and calculate an aging index of the transformer oil by combining the first electrical conductivity and the at least one second electrical conductivity to obtain an aging degree evaluation result of the transformer oil; wherein each infrared light absorption rate corresponds to the characteristic frequency of each aging product.
In this embodiment, the aging evaluation module 104 obtains an infrared light absorption rate of each aging product, and calculates an aging index of the transformer oil by combining the first electrical conductivity and the at least one second electrical conductivity, specifically:
the aging evaluation module 104 acquires the infrared absorption rate x of the aging producti1、Xi2、…、ximIn combination with said first electrical conductivity σi1Said at least one second electrical conductivity σi2、σi3、σi4And σi5Performing multiple linear regression analysis according to the following formula to obtain the aging index y of the transformer oil in the ith testi：
yi＝b0+b1σi1+b2σi2+…+b5σi5+c1xi1+c2xi2+c3xi3+…+cmXim+Di；
Wherein, b0Is intercept, DiFor residual, the number of correction set samples is n, the number of spectra is m, and n > m + 5.
In this embodiment, the conductivity obtaining module 103 calculates the first conductivity of the transformer oil according to the polarization curve, the non-polarization curve and the dc voltage, in combination with the capacitance of the conductive electrodes at the two ends of the transformer oil, specifically:
the conductivity acquisition module 103 acquires the polarization curve ip(t) the non-polarization curve id(t) and the DC voltage U0Calculating a first electrical conductivity σ of the transformer oil according to:
wherein, C0Capacitance of the conductive electrodes at both ends of the transformer oil, epsilon0Is the dielectric constant of the transformer oil.
Correspondingly, the embodiment of the invention also provides a sensing system for the aging degree of the transformer oil, which comprises a computer and an infrared composite sensor (refer to fig. 3). The infrared composite sensor is connected with the transformer 1 to be measured and is used for measuring the conductivity and the aging degree of the transformer oil of the transformer 1 to be measured.
The computer is used as an execution main body and used for executing the method for evaluating the aging degree of the transformer oil. The infrared composite sensor comprises a conductive electrode 2, a conductive cell 3, an electromagnetic shielding box 4, a thermostat 5, an infrared absorption cell 6 and a sapphire window 7.
The first end of the conductivity cell 3 is connected with one output end of the transformer 1 to be tested; the second end of the conductivity cell 3 is connected with the first end of the infrared absorption cell 6, and the second end of the infrared absorption cell 6 is connected with one input end of the transformer 1 to be tested. In the running process of the transformer 1 to be tested, the transformer oil flows out from one output end of the transformer 1 to be tested, enters the conductivity cell 3, flows in from one input end of the transformer 1 to be tested after passing through the infrared absorption cell 6, and flows back into the transformer 1 to be tested again.
An electromagnetic shielding box 4 is arranged outside the conductivity cell 3, and the electromagnetic shielding box 4 is used for shielding the influence of an electromagnetic field of an external environment on a test process (the electromagnetic shielding box is necessary due to on-line and real-time test). And a constant temperature box 5 is also arranged outside the electromagnetic shielding box 4 and used for eliminating the influence of temperature on the conductivity.
And two opposite planes of the conductivity cell 3 are provided with conductivity electrodes 2 for measuring the conductivity of the transformer oil. The conductive electrode 2 adopts a bright platinum electrode, so that the influence of capacitance change on a test result due to the adsorption of a platinum black electrode on trace moisture is prevented. Meanwhile, the surface area of the conductive electrodes 2 is properly increased relative to the conductive electrodes in the prior art, and the distance between the conductive electrodes 2 is properly reduced, so that the capacitance C of the conductive electrodes 2 is increased0. Since the conductivity is determined for an arbitrary sample, when the capacitance C is determined0When the current value becomes larger, the corresponding current value change value becomes larger, i.e. ip(t)-idThe greater (t) and thus the higher the sensitivity, the more accurate the conductivity obtained1。
The infrared absorption cell 6 is used for measuring the infrared light absorption rate of each aging product of the transformer oil under the irradiation of infrared incident light; and the infrared light absorption rate corresponds to the characteristic frequency of each aging product one by one. Sapphire windows 7 are arranged at the incident position and the emergent position of the infrared incident light of the infrared absorption pool 6, so that the corrosion of moisture in the transformer oil sample is avoided, and the service life of the infrared absorption pool 6 is prolonged; meanwhile, a plurality of layers of silica gel gaskets are arranged between the sapphire windows 7. The number of piles through adjusting the silica gel packing ring can adjust the distance between roof beam sapphire window 7 to change infrared absorption cell 6's size, and then adjust the light path length of infrared incident light in infrared absorption cell 6, so that the concentration scope that the length of light path can the different ageing products of adaptation improves the measuring accuracy.
Compared with the prior art, the embodiment of the invention has the following beneficial effects:
the embodiment of the invention provides a method and a device for evaluating the aging degree of transformer oil and a sensing system, wherein the method comprises the following steps: respectively collecting polarized current and non-polarized current of the transformer oil under direct current voltage in real time, and recording a polarization curve and a non-polarization curve of the transformer oil under the direct current voltage according to the collected polarized current and the non-polarized current; respectively acquiring not less than one voltage effective value and not less than one current effective value of the transformer oil under each alternating current excitation signal in real time; calculating first conductivity of the transformer oil according to the polarization curve, the non-polarization curve and the direct current voltage by combining capacitance of conductive electrodes at two ends of the transformer oil; respectively calculating at least one second conductivity of the transformer oil according to the at least one voltage effective value and the at least one current effective value; and acquiring the infrared light absorption rate of each aging product, and calculating the aging index of the transformer oil by combining the first conductivity and the at least one second conductivity to obtain the aging degree evaluation result of the transformer oil. Compared with the prior art, the method can be used for testing on line, and the influence of impurities on the conductivity of the transformer oil is considered by acquiring at least one conductivity of the transformer oil under the direct-current voltage and the alternating-current voltage, so that the accuracy and the real-time performance of the test are improved.
The above-mentioned embodiments are provided to further explain the objects, technical solutions and advantages of the present invention in detail, and it should be understood that the above-mentioned embodiments are only examples of the present invention and are not intended to limit the scope of the present invention. It should be understood that any modifications, equivalents, improvements and the like, which come within the spirit and principle of the invention, may occur to those skilled in the art and are intended to be included within the scope of the invention.
Claims (10)
1. A method for evaluating the aging degree of transformer oil is characterized by comprising the following steps:
respectively collecting polarized current and non-polarized current of the transformer oil under direct current voltage in real time, and recording a polarization curve and a non-polarization curve of the transformer oil under the direct current voltage according to the collected polarized current and the non-polarized current; wherein the polarization curve is a curve of the polarization current of the transformer oil along with the change of time; the non-polarization curve is a curve of the non-polarization current of the transformer oil along with the change of time;
respectively acquiring not less than one voltage effective value and not less than one current effective value of the transformer oil under each alternating current excitation signal in real time; wherein each alternating current excitation signal corresponds to a type of aging product;
calculating first conductivity of the transformer oil according to the polarization curve, the non-polarization curve and the direct current voltage by combining capacitance of conductive electrodes at two ends of the transformer oil; respectively calculating not less than one second conductivity of the transformer oil according to the not less than one voltage effective value and the not less than one current effective value;
acquiring the infrared light absorptivity of each aging product, and calculating the aging index of the transformer oil by combining the first conductivity and the at least one second conductivity to obtain the aging degree evaluation result of the transformer oil; wherein each infrared light absorption rate corresponds to the characteristic frequency of each aging product.
2. The method for evaluating the aging degree of transformer oil according to claim 1, wherein the infrared light absorption rate of each aging product is obtained, and the aging index of the transformer oil is calculated by combining the first electrical conductivity and the at least one second electrical conductivity, specifically:
obtaining the infrared absorptivity x of the aged producti1、xi2、…、ximIn combination with said first electrical conductivity σi1Said at least one second electrical conductivity σi2、σi3、σi4And σi5Performing multiple linear regression analysis according to the following formula to obtain the aging index y of the transformer oil in the ith testi：
yi＝b0+b1σi1+b2σi2+…+b5σi5+c1xi1+c2xi2+c3xi3+…+cmxim+Di；
Wherein, b0Is intercept, DiFor residual, the number of correction set samples is n, the number of spectra is m, and n > m + 5.
3. The method for evaluating the aging degree of transformer oil according to claim 1, wherein the first electrical conductivity of the transformer oil is calculated according to the polarization curve, the non-polarization curve and the dc voltage, in combination with the capacitance of the conductive electrodes at two ends of the transformer oil, specifically:
obtaining the polarization curve ip(t) the non-polarization curve id(t) and the DC voltage U0Calculating a first electrical conductivity σ of the transformer oil according to:
wherein, C0Capacitance of the conductive electrodes at both ends of the transformer oil, epsilon0Is the dielectric constant of the transformer oil.
4. The device for evaluating the aging degree of the transformer oil is characterized by comprising a first acquisition module, a second acquisition module, a conductivity acquisition module and an aging evaluation module; wherein the content of the first and second substances,
the first acquisition module is used for acquiring the polarized current and the non-polarized current of the transformer oil under the direct current voltage in real time respectively, and recording the polarized curve and the non-polarized curve of the transformer oil under the direct current voltage according to the acquired polarized current and the non-polarized current; wherein the polarization curve is a curve of the polarization current of the transformer oil along with the change of time; the non-polarization curve is a curve of the non-polarization current of the transformer oil along with the change of time;
the second acquisition module is used for respectively acquiring not less than one voltage effective value and not less than one current effective value of the transformer oil under each alternating current excitation signal in real time; each alternating current excitation signal corresponds to the type of an aging product;
the conductivity acquisition module is used for calculating first conductivity of the transformer oil according to the polarization curve, the non-polarization curve and the direct current voltage by combining the capacitance of the conductive electrodes at two ends of the transformer oil; respectively calculating not less than one second conductivity of the transformer oil according to the not less than one voltage effective value and the not less than one current effective value;
the aging evaluation module is used for acquiring the infrared light absorption rate of each aging product, and calculating the aging index of the transformer oil by combining the first conductivity and the at least one second conductivity to obtain the aging degree evaluation result of the transformer oil; wherein each infrared light absorption rate corresponds to the characteristic frequency of each aging product.
5. The apparatus for evaluating the aging degree of transformer oil according to claim 4, wherein the aging evaluation module obtains an infrared light absorption rate of each aging product, and calculates an aging index of the transformer oil by combining the first conductivity and the at least one second conductivity, specifically:
the aging evaluation module acquires the infrared absorptivity x of the aging producti1、xi2、…、ximIn combination with said first electrical conductivity σi1Said at least one second electrical conductivity σi2、σi3、σi4And σi5Performing multiple linear regression analysis according to the following formula to obtain the aging index y of the transformer oil in the ith testi：
yi＝b0+b1σi1+b2σi2+…+b5σi5+c1xi1+c2xi2+c3xi3+…+cmxim+Di；
Wherein, b0Is intercept, DiFor residual, the number of correction set samples is n, the number of spectra is m, and n > m + 5.
6. The apparatus for evaluating the aging degree of transformer oil according to claim 4, wherein the conductivity obtaining module calculates the first conductivity of the transformer oil according to the polarization curve, the non-polarization curve and the dc voltage, in combination with the capacitance of the conductive electrodes at two ends of the transformer oil, specifically:
the conductivity acquisition module acquires the polarization curve ip(t) the non-polarization curve id(t) and the DC voltage U0Calculating a first electrical conductivity σ of the transformer oil according to:
wherein, C0Capacitance of the conductive electrodes at both ends of the transformer oil, epsilon0Is the dielectric constant of the transformer oil.
7. The sensing system for the aging degree of the transformer oil is characterized by comprising a computer and an infrared composite sensor;
the infrared composite sensor comprises a conductance cell and an infrared absorption cell; the first end of the conductivity cell is connected with one output end of the transformer to be tested; the second end of the conductivity cell is connected with the first end of the infrared absorption cell, and the second end of the infrared absorption cell is connected with one input end of the transformer to be tested;
two opposite planes of the conductivity cell are provided with conductivity electrodes for measuring the conductivity of the transformer oil;
the infrared absorption cell is used for measuring the infrared light absorption rate of each aging product of the transformer oil under the irradiation of infrared incident light; the infrared light absorption rate corresponds to the characteristic frequency of each aging product one by one;
the computer is used for executing the method for evaluating the aging degree of the transformer oil as claimed in any one of claims 1 to 3.
8. The system for sensing the level of transformer oil aging of claim 7, wherein said electrically conductive electrode comprises a bright platinum electrode.
9. The system for sensing the aging degree of transformer oil as claimed in claim 7, wherein an electromagnetic shielding box is further provided outside the conductivity cell.
10. The system for sensing the aging degree of transformer oil as claimed in claim 7, wherein sapphire windows are arranged at the incident position and the emergent position of the infrared incident light of the infrared absorption cell; and a plurality of layers of silica gel gaskets are arranged between the sapphire windows.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116482216A (en) * | 2023-06-19 | 2023-07-25 | 国网安徽省电力有限公司电力科学研究院 | Method for detecting aging degree of insulating oil of transformer |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116482216A (en) * | 2023-06-19 | 2023-07-25 | 国网安徽省电力有限公司电力科学研究院 | Method for detecting aging degree of insulating oil of transformer |
| CN116482216B (en) * | 2023-06-19 | 2023-08-25 | 国网安徽省电力有限公司电力科学研究院 | Method for detecting aging degree of insulating oil of transformer |
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