Monitoring device and monitoring method for dissolved gas in on-load tap-changer oil

Abstract

The invention discloses an on-load tap-changer oil dissolved gas monitoring device which comprises a variable capacity container, a two-way electromagnetic valve, a switching mechanism, a chromatographic column system, a high-sensitivity detector and a low-sensitivity detector which are sequentially connected, and the top and the bottom of the variable capacity container are connected through a circulating pump to form a gas flow loop. The variable-capacity container is connected with the on-load tap-changer through a connecting pipe, the switching mechanism is connected with at least two quantitative pipes with different capacities, and the switching mechanism is used for equally transferring gas in the variable-capacity container to the quantitative pipes and then sequentially transferring the gas in the quantitative pipes to the chromatographic column system. The invention further discloses a method for monitoring the dissolved gas in the on-load tap-changer oil. According to the monitoring device and the monitoring method for the dissolved gas in the oil of the on-load tap-changer, the detection range of the concentration is improved, a concentration blind area which is not detected and misjudgment of signal saturation can be avoided, and the detection accuracy is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of on-load tap changer oil analysis detection in power systems, and particularly relates to an on-load tap changer oil dissolved gas monitoring device and a monitoring method. BACKGROUND

[0002] Current on-load tap changer oil (referring to special mineral insulating oil used for insulation, cooling and arc extinguishing during the operation of on-load tap changer, the performance of which directly affects the insulation reliability of tap changer) dissolved gas monitoring (by detecting the types and concentrations of characteristic gases such as methane, ethylene, ethane, acetylene, carbon monoxide, carbon dioxide, hydrogen and other gases dissolved in the oil, to predict tap changer internal overheating, partial discharge, arc discharge and other faults, to avoid equipment burning, power grid shutdown and other major accidents) mainly relies on traditional oil chromatography online monitoring devices, and the core structure of which generally adopts a single configuration of "fixed degassing amount degassing + single quantitative tube sampling + single detector detection". When facing the wide concentration fluctuation of "ppm level trace gas (initial stage of fault) - 10 5 ppm level high gas (developing stage of fault)" of on-load tap changer, the configuration cannot simultaneously meet the detection needs of low concentration and high concentration. The specific defects are as follows: 1) The degassing amount and sampling amount of the traditional device are fixed values, which cannot be dynamically adjusted according to the oil sample concentration. When the oil sample is of low concentration, the fixed degassing amount and fixed sampling volume result in insufficient enrichment of the target gas in the gas phase, which leads to weak signals received in the subsequent detection link and easy occurrence of "undetected" or misjudgment. When the oil sample is of high concentration, the fixed degassing amount and fixed sampling volume make the concentration of the target gas in the gas phase too high, which exceeds the processing capacity of the subsequent sampling and detection modules, directly causing signal overload problem; 2) The traditional device is usually equipped with a single sensitivity detector, and the linear detection upper limit thereof is usually ≤2000ppm. When facing low concentration oil samples, although the detection needs can be met, the precision is easily affected due to the signal weakening in the previous degassing and sampling links. When facing high concentration oil samples (such as acetylene ≥10000ppm, hydrogen ≥10 5 ppm), the linear range of the detector cannot be covered at all, directly resulting in signal saturation and detection failure, and accurate concentration data cannot be obtained. In summary, the defects of the series connection of "fixed degassing amount + single quantitative tube + single detector" result in that the traditional device cannot achieve stable and accurate monitoring in a wide range in the full working condition monitoring of on-load tap changer, either the detection precision is insufficient for low concentration, or the detection is completely failed for high concentration.

[0003] That is, the conventional oil chromatographic device adopts a single structure of "fixed degassing amount + single quantitative tube + single detector", and only one set of detection data can be output for single sample injection, which has two major contradictions that cannot be reconciled: (1) Concentration adaptation contradiction: if designed according to low concentration requirements (small degassing amount + large quantitative tube + high sensitivity detector), high concentration oil samples will cause signal saturation; if designed according to high concentration requirements (large degassing amount + small quantitative tube + low sensitivity detector), low concentration oil sample signal is weak and cannot be detected, and single data cannot cover the "low-high" full concentration; (2) Periodic efficiency contradiction: if you want to cover a wide range, you need to manually adjust the degassing amount, replace the quantitative tube and repeat the sample (at least 4 times to cover 4 concentration sections), and the single sample cycle is 2h, and the 4 times cycle is 8h, which cannot meet the real-time demand of online monitoring.

[0004] The existing Chinese patent document with application number 201810073972.1 discloses an online monitoring device for dissolved gas in insulating oil, which comprises a degassing cylinder, an oil removal chamber, a linear stepper motor and a chromatographic analysis gas path module; the linear stepper motor is arranged directly below the degassing cylinder and is connected with the piston inside the degassing cylinder, one side of the upper part of the degassing cylinder is connected with the oil taking port of the transformer through the oil inlet electromagnetic valve, the other side of the upper part of the degassing cylinder is connected with the oil return port of the transformer through the oil discharge electromagnetic valve, the top of the degassing cylinder is communicated with the oil removal chamber, and the top of the oil removal chamber is connected with the chromatographic analysis gas path module. The oil sampling process: the oil sample volume entering the degassing cylinder is controlled by the displacement control of the linear stepper motor, and the cooperation of the oil inlet electromagnetic valve, the oil discharge electromagnetic valve and the emptying electromagnetic valve. The degassing process: the oil inlet electromagnetic valve, the oil discharge electromagnetic valve and the emptying electromagnetic valve are closed, the six-way valve is switched to the degassing state, the linear stepper motor drives the piston to move downward, a local vacuum is formed between the top of the piston and the oil sample, and the dissolved gas in the insulating oil is continuously separated out and moves to the top of the degassing cylinder, the oil removal chamber and the quantitative tube under the action of buoyancy during the continuous downward movement of the piston. The balance quantitative process: after the degassing is completed, the piston position is adjusted to keep the internal pressure of the degassing cylinder at one standard atmosphere, and the components in the oil and the separated gas are dynamically balanced after a period of static state; the volume of the separated gas is calculated according to the relative position of the piston under one standard atmosphere, and the concentration of the dissolved gas in the oil is calculated by further using the component gas concentration analyzed by the chromatographic analysis module and the gas solubility distribution coefficient between gas and liquid under the current temperature and pressure. The online monitoring device for dissolved gas in insulating oil has the following disadvantages: 1) a local vacuum needs to be formed between the top of the piston and the oil sample for degassing, which has a complex structure, is high and difficult to control; 2) only the component gas concentration analyzed by the chromatographic analysis module is used, which has poor accuracy and cannot realize stable and accurate monitoring in a wide range.

[0005] The Chinese patent document with the present application number 202123066501.4 discloses a high-precision transformer oil dissolved gas concentration and gas content online monitoring device, which comprises a carrier gas source, a full-automatic degassing module and a full-automatic detection module. The carrier gas source is connected with the full-automatic degassing module and the full-automatic detection module respectively. The full-automatic degassing module and the full-automatic detection module are connected. The full-automatic degassing module comprises a headspace degassing cylinder. The full-automatic detection module is a chromatographic analysis module with a detection limit lower than 0.1 muL / L. The use method of the online monitoring device is as follows: first, flush the headspace degassing cylinder. After flushing, fill the oil. Balance the pressure in the cylinder with the external pressure by supplementing the gas. The balance gas used is helium with a purity of more than 99.999%. Circulating degassing; the degassed gas is detected and judged by the full-automatic detection module after being constant volume by the constant volume tube. Although circulating degassing is adopted, the detection is still performed by the chromatographic column, and there is still the problem of poor accuracy and inability to realize stable and accurate monitoring in a wide range. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art, provide a load tap changer oil dissolved gas monitoring device and monitoring method which improve the detection range of concentration, avoid the "undetected" "concentration blind area" and signal saturation misjudgment, and improve the detection accuracy.

[0007] To solve the above technical problems, the present application adopts the following technical solutions: A load tap changer oil dissolved gas monitoring device, comprising a variable volume container, a two-way electromagnetic valve, a switching mechanism, a chromatographic column system, a high sensitivity detector and a low sensitivity detector connected in sequence. The top and bottom of the variable volume container are connected by a circulating pump to form a gas flow loop. The variable volume container is connected to the load tap changer through a connecting pipe. The switching mechanism is connected to at least two constant volume tubes with different capacities. The switching mechanism is used to divide and transfer the gas in the variable volume container to each constant volume tube, and then transfer the gas in each constant volume tube to the chromatographic column system in turn.

[0008] As a further improvement of the above technical solution: The load tap changer oil dissolved gas monitoring device further comprises two multi-way electromagnetic valves connected to the switching mechanism, and each constant volume tube is connected in parallel between the two multi-way electromagnetic valves.

[0009] The switching mechanism is a six-way electromagnetic valve, and the constant volume tube comprises a large capacity constant volume tube and a small capacity constant volume tube with smaller capacity than the large capacity constant volume tube.

[0010] A vertical piston rod is arranged in the variable volume container. The bottom end of the piston rod extends from the bottom of the variable volume container and is connected to a stepping motor.

[0011] The connecting pipe is provided with a filter.

[0012] The variable capacity container is provided with a balance intake part and a pressure sensor.

[0013] The on-load tap changer oil dissolved gas monitoring device further comprises a signal processing module, and the chromatographic column system, the high-sensitivity detector and the low-sensitivity detector are connected with the signal processing module.

[0014] The on-load tap changer oil dissolved gas monitoring method is performed by using the on-load tap changer oil dissolved gas monitoring device, and comprises the following steps: S1, degassing: the on-load tap changer supplies a variable capacity container with a set amount of insulating oil, and the capacity of the variable capacity container is started in a constant value state to start a circulating pump, so that the gas in the variable capacity container flows out from the top and flows into the bottom, until the gas phase and the liquid phase in the variable capacity container reach gas-liquid equilibrium, so as to complete the degassing of the insulating oil in the variable capacity container; S2, gas sub-packaging: the gas in the variable capacity container is evenly transferred to each quantitative pipe through the switching mechanism; S3, sample injection detection: the gas in each quantitative pipe is sequentially transferred to the chromatographic column system through the switching mechanism, and the concentration values of each component in the gas are detected by the high-sensitivity detector and the low-sensitivity detector; S4, recombination detection: the capacity of the variable capacity container is adjusted to different values, and S1 to S3 are repeated, so as to detect the comprehensive values of each component in the gas under the combination configuration of each capacity of the variable capacity container and different quantitative pipes; S5, obtaining optimal detection value: the combination configuration corresponding to the highest comprehensive value is screened out as the optimal combination configuration, and the concentration value detected by the optimal combination configuration is taken as the optimal detection value.

[0015] As a further improvement of the above technical solution: In S4, the peak shape S1, the peak height linear region S2, the signal-to-noise ratio S3 and the historical trend deviation S4 of each component in the gas under four kinds of combination configurations of a large-capacity variable capacity container + a large-capacity quantitative pipe + a high-sensitivity detector, a large-capacity variable capacity container + a small-capacity quantitative pipe + a high-sensitivity detector, a small-capacity variable capacity container + a large-capacity quantitative pipe + a low-sensitivity detector, and a small-capacity variable capacity container + a small-capacity quantitative pipe + a low-sensitivity detector are detected, and the comprehensive value is set as S, S=0.4S1+0.25S2+0.2S3+0.15S4.

[0016] The optimal combination configuration result obtained in S5 is stored in a historical database for parameter matching next time.

[0017] Compared with the prior art, the advantages of the present application are: The on-load tap changer oil dissolved gas monitoring device of the application, first, adopts a variable volume container with adjustable volume, at least two constant volume tubes with different volume sizes, a chromatographic column system, a high sensitivity detector and a low sensitivity detector, realizes detection of at least four kinds of combination configurations (one capacity of the variable volume container corresponds to two kinds of combination configurations), improves the concentration detection range (concentration range), and is beneficial to avoid the "undetected" "concentration blind area" and the misjudgment of signal saturation; second, the detection can be reorganized to obtain the optimal detection value and improve the detection accuracy.

[0018] The on-load tap changer oil dissolved gas monitoring method of the application, first, adopts a variable volume container with adjustable volume, at least two constant volume tubes with different volume sizes, a chromatographic column system, a high sensitivity detector and a low sensitivity detector, realizes detection of at least four kinds of combination configurations (one capacity of the variable volume container corresponds to two kinds of combination configurations), improves the concentration detection range (concentration range), and is beneficial to avoid the "undetected" "concentration blind area" and the misjudgment of signal saturation; second, the detection can be reorganized to obtain the optimal detection value and improve the detection accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a structure schematic view of the on-load tap changer oil dissolved gas monitoring device of the application.

[0020] The various reference numerals in the drawings represent: 1, connecting pipe; 2, filter; 3, pressure sensor; 4, variable volume container; 5, circulating pump; 6, piston rod; 7, stepping motor; 8, multi-way electromagnetic valve; 9, multi-way electromagnetic valve; 10, switching mechanism; 11, chromatographic column system; 12, high sensitivity detector; 13, low sensitivity detector; 20, large capacity constant volume tube; 21, small capacity constant volume tube; 22, signal processing module; 23, two-way electromagnetic valve. DETAILED DESCRIPTION

[0021] The application will be further described in detail below in combination with the drawings and specific embodiments.

[0022] In the description of the application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0023] In addition, the terms "first", "second", etc. are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0024] In the present application, unless otherwise explicitly specified and limited, the terms "assembly", "connection", "linkage", "fixation" and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0025] Embodiment one: Figure 1 An embodiment of the on-load tap changer oil dissolved gas monitoring device of the present application is shown, the on-load tap changer oil dissolved gas monitoring device of the embodiment includes a variable capacity container 4, a two-way electromagnetic valve 23, a switching mechanism 10, a chromatographic column system 11, a high sensitivity detector 12 and a low sensitivity detector 13 connected in sequence, the top and bottom of the variable capacity container 4 are connected into a gas flow circuit through a circulating pump 5, the variable capacity container 4 is connected with the on-load tap changer through a connecting pipe 1, the switching mechanism 10 is connected with at least two constant volume tubes (20, 21) with different capacities, the switching mechanism 10 is used to first divide and transfer the gas in the variable capacity container 4 to each constant volume tube (20, 21), and then transfer the gas in each constant volume tube (20, 21) to the chromatographic column system 11 in sequence.

[0026] The monitoring process of the dissolved gas monitoring device in the on-load tap changer oil is as follows: first step, degassing: the on-load tap changer supplies a set amount of insulating oil to the variable volume container 4, and the circulating pump 5 is started under the condition of a constant volume of the variable volume container 4, so that the gas in the variable volume container 4 flows out from the top and flows into the bottom until the gas phase and the liquid phase in the variable volume container 4 reach a gas-liquid equilibrium, thereby completing the degassing of the insulating oil in the variable volume container 4; second step, gas dispensing: the gas in the variable volume container 4 is evenly divided and transferred to each dosing tube (20, 21) through the switching mechanism 10; third step, sample injection detection: the gas in each dosing tube (20, 21) is sequentially transferred to the chromatographic column system 11 through the switching mechanism 10, and the concentration values of each component in the gas are detected by the high-sensitivity detector 12 and the low-sensitivity detector 13; fourth step, recombination detection: the volume of the variable volume container 4 is adjusted to different values, and steps S1 to S3 are repeated, thereby obtaining the comprehensive values of each component (methane, ethylene, ethane, acetylene, carbon monoxide, carbon dioxide, hydrogen, etc.) in the gas under the combination configuration of each volume of the variable volume container 4 and different dosing tubes (20, 21); fifth step, obtaining the optimal detection value: the combination configuration corresponding to the highest comprehensive value is selected as the optimal combination configuration, and the concentration value detected by the optimal combination configuration is taken as the optimal detection value.

[0027] The dissolved gas monitoring device in the on-load tap changer oil has the following advantages: first, the variable volume container 4 with adjustable volume, at least two dosing tubes (20, 21) with different volumes, the chromatographic column system 11, the high-sensitivity detector 12, and the low-sensitivity detector 13 are combined to realize detection of at least four combination configurations (one volume of the variable volume container 4 corresponds to two combination configurations), thereby improving the concentration detection range (concentration range) and avoiding the occurrence of "undetected" "concentration blind area" and signal saturation misjudgment; second, recombination detection is performed to obtain the optimal detection value, thereby improving the detection accuracy.

[0028] Further, in the embodiment, the dissolved gas monitoring device in the on-load tap changer oil further comprises two multi-way electromagnetic valves (8, 9) connected to the switching mechanism 10, and each dosing tube (20, 21) is connected in parallel between the two multi-way electromagnetic valves (8, 9).

[0029] Further, in the embodiment, the switching mechanism 10 is a six-way electromagnetic valve, and the dosing tubes (20, 21) include a large-capacity dosing tube 20 and a small-capacity dosing tube 21 with a smaller volume than the large-capacity dosing tube 20.

[0030] Further, in the embodiment, the variable volume container 4 is provided with a vertical piston rod 6, and the bottom end of the piston rod 6 extends out of the bottom of the variable volume container 4 and is connected to a stepping motor 7.

[0031] Gas dispensing process: the gas in the variable volume container 4 is evenly transferred to the large capacity dosing tube 20 and the larger capacity dosing tube 20 through the switching mechanism 10. The six-way electromagnetic valve can include a first interface 14, a second interface 15, a third interface 16, a fourth interface 17, a fifth interface 18 and a sixth interface 19, a two-way electromagnetic valve 23 is connected with the first interface 14, two multi-way electromagnetic valves (8, 9) are connected with the first interface 14 and the sixth interface 19 respectively, the third interface 16 is connected with the chromatographic column system 11, and the two multi-way electromagnetic valves (8, 9) are three-way electromagnetic valves. After gas-liquid balance, the two-way electromagnetic valve 23 is opened, and the gas dispensing is carried out, specifically: the six-way electromagnetic valve makes the first interface 14 and the second interface 15, the third interface 16 and the fifth interface 18, the fourth interface 17 and the sixth interface 19 communicate, and the two multi-way electromagnetic valves (8, 9) control the gas path to connect the large capacity dosing tube (20), at this time the stepping motor 7 makes the piston rod 6 push half of the gas phase into the large capacity dosing tube 20, and the large capacity dosing tube 20 is completed. The washing and sample storage of the large capacity dosing tube 20; then the six-way electromagnetic valve switches the first interface 14 and the third interface 16, the second interface 15 and the fourth interface 17, the fifth interface 18 and the sixth interface 19, and the two multi-way electromagnetic valves (8, 9) control the gas path to connect the small capacity dosing tube 21, at this time the stepping motor 7 makes the piston rod 6 push half of the gas phase into the small capacity dosing tube 21, and the small capacity dosing tube 21 is completed. The washing and sample storage of the small capacity dosing tube 21.

[0032] Further, in the embodiment, the connecting pipe 1 is provided with a filter 2.

[0033] Further, in the embodiment, the variable volume container 4 is provided with a balance gas inlet portion and a pressure sensor 3.

[0034] Further, in the embodiment, the on-load tap changer oil dissolved gas monitoring device further comprises a signal processing module 22, and the chromatographic column system 11, the high sensitivity detector 12 and the low sensitivity detector 13 are connected with the signal processing module 22. The signal processing module 22 can calculate the required quantity values such as the comprehensive value and the concentration value of each component in the gas through the detection results of the chromatographic column system 11, the high sensitivity detector 12 and the low sensitivity detector 13.

[0035] Further, in the embodiment, the on-load tap changer oil dissolved gas monitoring device further comprises an intelligent processing module, and the intelligent processing module (control module) is connected with the stepping motor 7, the pressure sensor 3, the two-way electromagnetic valve 23, the switching mechanism 10, the circulating pump 5, the two multi-way electromagnetic valves (8, 9) and the signal processing module 22 respectively.

[0036] The oil-gas separation stage can be: the on-load tap changer oil sample (insulating oil) enters the variable capacity container 4 through the filter 2, the intelligent processing module calls historical data, and the capacity of the variable capacity container 4, that is, the degassing amount, is adjusted by the stepper motor 7, that is, if the previous concentration is high, the capacity of the variable capacity container 4 is reduced to an appropriate gear, specifically, the piston rod 6 moves, the volume of the extracted oil sample is reduced, the volume of the extracted balance gas is increased, the pressure sensor 3 feeds back the pressure in the variable capacity container 4 in real time, the gas phase and liquid phase volumes can be accurately obtained, the circulating pump 5 is started, the top air body in the variable capacity container 4 is pushed from the bottom of the oil sample to form uniform bubbles, the bubble increases the gas-liquid contact area, and the dissolved gas is transferred from the oil phase to the gas phase; the degassing amount does not need to be adjusted during the operation of the circulating pump 5 (the position of the piston rod 6 is fixed, the circulation only strengthens the mass transfer, and the total volume of the gas phase does not change).

[0037] The relationship between the degassing amount and the degassing concentration in the gas-liquid equilibrium relationship [“GB T17623-2017 Gas Chromatographic Determination of Dissolved Gas Component Content in Insulating Oil”]: it is known that the gas-liquid distribution equilibrium formula of insulating oil is Cil=Ki x Cig, the sum of the gas phase and the liquid phase is a fixed value: Vg+Vl=V, and the material conservation (Xi x Vl=Cig x Vg+Cil x Vl) before and after the oil sample balance is brought in, and Cig=Xi x Vl / ((Ki-1) Vl+V) is obtained, wherein Xi, Ki and V are fixed values, and Cig monotonically decreases with the decrease of Vl. If the oil inlet amount Vl is reduced, the concentration Cig of the i component in the gas phase can be indirectly reduced, and the upper limit of the system detection is increased.

[0038] Ki - distribution coefficient of dissolved gas i component after gas-liquid equilibrium at test temperature; Cil - concentration of dissolved gas i component in oil under equilibrium condition; Cig - concentration of dissolved gas i component in gas phase under equilibrium condition; Vg - gas phase volume; Vl - oil sample volume; V - capacity (total volume) of the variable capacity container 4; Xi - concentration of dissolved gas i component in the oil sample; Example two: A dissolved gas monitoring method in an on-load tap changer oil, which is carried out by using the dissolved gas monitoring device in the on-load tap changer oil of example one, and includes the following steps: S1, degassing: the on-load tap changer supplies a variable-capacity container 4 with a set amount of insulating oil, and the capacity of the variable-capacity container 4 is started in a fixed state to start a circulating pump 5, so that the gas in the variable-capacity container 4 flows out from the top and flows into the bottom until the gas phase and the liquid phase in the variable-capacity container 4 reach a gas-liquid balance, so as to complete the degassing of the insulating oil in the variable-capacity container 4; S2, gas dispensing: the gas in the variable-capacity container 4 is evenly transferred to each dosing tube (20, 21) through the switching mechanism 10; S3, sample injection detection: the gas in each dosing tube (20, 21) is sequentially transferred to the chromatographic column system 11 through the switching mechanism 10, and then the concentration values of each component in the gas are detected by the high-sensitivity detector 12 and the low-sensitivity detector 13; S4, recombination detection: the capacity of the variable-capacity container 4 is adjusted to different values, and S1 to S3 are repeated, so as to detect the comprehensive values of each component in the gas under the combination configuration of the variable-capacity container 4 with different dosing tubes (20, 21) at each capacity; S5, obtaining the optimal detection value: the combination configuration corresponding to the highest comprehensive value is screened out as the optimal combination configuration, and the concentration value detected by the optimal combination configuration is taken as the optimal detection value.

[0039] The on-load tap changer oil dissolved gas monitoring method has the following advantages: first, the variable-capacity container 4 with adjustable capacity, at least two dosing tubes (20, 21) with different capacities, the chromatographic column system 11, the high-sensitivity detector 12, and the low-sensitivity detector 13 are combined to realize the detection of at least four combination configurations (one capacity of the variable-capacity container 4 corresponds to two combination configurations), which improves the concentration detection range (concentration range) and is beneficial to avoid the “concentration blind area” of “undetected” and the misjudgment of signal saturation; second, the recombination detection is used to obtain the optimal detection value, which improves the detection accuracy.

[0040] Further, in the embodiment, In S4, the peak shape S1, the peak height linear region S2, the signal-to-noise ratio S3, and the historical trend deviation S4 of each component in the gas under four combination configurations of the large-capacity variable-capacity container 4+the large-capacity dosing tube 20+the high-sensitivity detector 12, the large-capacity variable-capacity container 4+the small-capacity dosing tube 21+the high-sensitivity detector 12, the small-capacity variable-capacity container 4+the large-capacity dosing tube 20+the low-sensitivity detector 13, and the small-capacity variable-capacity container 4+the small-capacity dosing tube 21+the low-sensitivity detector 13 are detected, and the comprehensive value is set as S, S=0.4S1+0.25S2+0.2S3+0.15S4.

[0041] The combination of the large-capacity variable-volume container 4 + the large-capacity burette 20 + the high-sensitivity detector 12 is configured such that the variable-volume container 4 is degassed in the large-capacity state, and half of the gas in the variable-volume container 4 first enters the large-capacity burette 20 and then enters the high-sensitivity detector 12 to obtain the peak shape S1, the peak height linear region S2, the signal-to-noise ratio S3, and the deviation from the historical trend S4 of each component in the gas. The combination of the large-capacity variable-volume container 4 + the small-capacity burette 21 + the high-sensitivity detector 12 is configured such that the variable-volume container 4 is degassed in the large-capacity state, and half of the gas in the variable-volume container 4 first enters the small-capacity burette 21 and then enters the high-sensitivity detector 12 to obtain the peak shape S1, the peak height linear region S2, the signal-to-noise ratio S3, and the deviation from the historical trend S4 of each component in the gas. The combination of the small-capacity variable-volume container 4 + the large-capacity burette 20 + the low-sensitivity detector 13 is configured such that the variable-volume container 4 is degassed in the small-capacity state, and half of the gas in the variable-volume container 4 first enters the large-capacity burette 20 and then enters the low-sensitivity detector 13 to obtain the peak shape S1, the peak height linear region S2, the signal-to-noise ratio S3, and the deviation from the historical trend S4 of each component in the gas. The combination of the small-capacity variable-volume container 4 + the small-capacity burette 21 + the low-sensitivity detector 13 is configured such that the variable-volume container 4 is degassed in the small-capacity state, and half of the gas in the variable-volume container 4 first enters the small-capacity burette 21 and then enters the low-sensitivity detector 13 to obtain the peak shape S1, the peak height linear region S2, the signal-to-noise ratio S3, and the deviation from the historical trend S4 of each component in the gas.

[0042] The four groups of combination configurations can correspond to specific concentration intervals, ① the combination of the large-capacity variable-volume container 4 + the large-capacity burette 20 + the high-sensitivity detector 12 is suitable for "low concentration (0.1-2000 ppm)", ② the combination of the large-capacity variable-volume container 4 + the small-capacity burette 21 + the high-sensitivity detector 12 is suitable for "low-to-medium concentration (1000-8000 ppm)", ③ the combination of the small-capacity variable-volume container 4 + the large-capacity burette 20 + the low-sensitivity detector 13 is suitable for "medium concentration (5000-5×10 4 ppm)", and ④ the combination of the small-capacity variable-volume container 4 + the small-capacity burette 21 + the low-sensitivity detector 13 is suitable for "high concentration (1×10 4 -1×10 5 ppm)", achieving a "segmented adaptation" design, so that the four groups of combination configurations seamlessly connect to each other and cover a super-wide range of "ppm level-10 5 ppm level". The overlapping regions set between adjacent concentration intervals (such as 1000 ppm overlap between ① and ②, and 3000 ppm overlap between ② and ③), the two groups of data in the overlapping regions can cross-verify (such as 5000 ppm concentration, both ② and ③ groups can output effective signals), avoiding "concentration blind area" and achieving redundant design in the overlapping regions.

[0043] Further, in the embodiment, the optimal combination configuration result obtained in S5 is stored in the historical database for next parameter matching. Since the monitoring process is generally monitored every set time period, the optimal combination configuration result obtained by the last monitoring process is stored in the historical database, and the capacity of the variable capacity container 4 in S1 of the next monitoring process can be adjusted according to the capacity of the variable capacity container 4 in the optimal combination configuration obtained by the last monitoring process or comprehensively adjusted according to the capacity of the variable capacity container 4 in the optimal combination configuration obtained by the previous multiple monitoring processes, so that the detection efficiency is improved.

[0044] The device can be built-in with a historical database, and the historical data of the device is automatically called before each degassing. If more than 80% of the historical data is high concentration (such as ≥5×10 4 ppm), the core parameters of the large-capacity variable capacity container 4+large-capacity fixed volume tube 20+low-sensitivity detector 13" are automatically matched, without the need for manual judgment. If it is the first detection, the "four-group combination configuration full detection" mode is started by default, and subsequent optimization and matching are based on the first data to realize "the more you use, the more intelligent you are".

[0045] Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art can make many possible changes and modifications to the technical solutions of the present application or modify equivalent embodiments with equivalent changes without departing from the scope of the technical solutions of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application should fall within the scope of protection of the technical solutions of the present application.

Claims

1. An on-load tap changer oil dissolved gas monitoring device, characterized by: The device comprises a variable volume container (4), a two-way electromagnetic valve (23), a switching mechanism (10), a chromatographic column system (11), a high sensitivity detector (12) and a low sensitivity detector (13) connected in sequence, the top and bottom of the variable volume container (4) are connected into a gas flow loop by a circulating pump (5), the variable volume container (4) is connected with an on-load tap changer through a connecting pipe (1), the switching mechanism (10) is connected with at least two constant volume tubes (20, 21) with different capacities, and the switching mechanism (10) is used for first dividing and transferring the gas in the variable volume container (4) to each constant volume tube (20, 21) and then transferring the gas in each constant volume tube (20, 21) to the chromatographic column system (11) in sequence.

2. The on-load tap changer oil dissolved gas monitoring apparatus of claim 1, wherein: The on-load tap changer oil dissolved gas monitoring device further comprises two multi-way electromagnetic valves (8, 9) connected with the switching mechanism (10) respectively, and each constant volume tube (20, 21) is connected in parallel between the two multi-way electromagnetic valves (8, 9).

3. The on-load tap changer oil dissolved gas monitoring apparatus of claim 2, wherein: The switching mechanism (10) is a six-way electromagnetic valve, and the constant volume tubes (20, 21) comprise a large-capacity constant volume tube (20) and a small-capacity constant volume tube (21) with a smaller capacity than the large-capacity constant volume tube (20).

4. The on-load tap changer oil dissolved gas monitoring apparatus of claim 1, wherein: The variable volume container (4) is provided with a vertical piston rod (6), the bottom end of the piston rod (6) extends out of the bottom of the variable volume container (4) and is connected with a stepping motor (7).

5. The on-load tap changer oil dissolved gas monitoring apparatus of claim 1, wherein: The connecting pipe (1) is provided with a filter (2).

6. The on-load tap changer oil dissolved gas monitoring apparatus of claim 1, wherein: The variable volume container (4) is provided with a balance gas inlet part and a pressure sensor (3).

7. The on-load tap changer oil dissolved gas monitoring apparatus of any one of claims 1 to 6, wherein: The on-load tap changer oil dissolved gas monitoring device further comprises a signal processing module (22), and the chromatographic column system (11), the high sensitivity detector (12) and the low sensitivity detector (13) are connected with the signal processing module (22).

8. A method of monitoring dissolved gases in oil of a load tap changer, characterized by The on-load tap changer oil dissolved gas monitoring device is performed by adopting any one of the devices in the items 1 to 7, and comprises the following steps: S1, degassing: the on-load tap changer supplies a constant amount of insulating oil to the variable volume container (4), the capacity of the variable volume container (4) is started under a constant value state to start the circulating pump (5), so that the gas in the variable volume container (4) flows out from the top and flows into the bottom, until the gas phase and the liquid phase in the variable volume container (4) reach gas-liquid equilibrium, so as to complete the degassing of the insulating oil in the variable volume container (4); S2, gas packaging: the gas in the variable volume container (4) is divided and transferred to each constant volume tube (20, 21) through the switching mechanism (10); S3, sample injection detection: the gas in each constant volume tube (20, 21) is transferred to the chromatographic column system (11) in sequence through the switching mechanism (10), and then the concentration values of each component in the gas are detected by the high sensitivity detector (12) and the low sensitivity detector (13); S4, recombination detection: the capacity of the variable volume container (4) is adjusted to different values, and S1 to S3 are repeated, so as to detect the comprehensive values of each component in the gas under the combination of the variable volume container (4) with different capacities and different constant volume tubes (20, 21). S5, obtaining the optimal detection value: screening the combination configuration corresponding to the highest comprehensive value as the optimal combination configuration, and the concentration value detected by the optimal combination configuration as the optimal detection value.

9. The on-load tap changer oil dissolved gas monitoring method according to claim 8, characterized in that: In S4, the peak shape S1, the peak height linear region S2, the signal-to-noise ratio S3, and the historical trend deviation S4 of each component in the gas under four combination configurations of the large-capacity variable-capacity container (4) + the large-capacity burette (20) + the high-sensitivity detector (12), the large-capacity variable-capacity container (4) + the small-capacity burette (21) + the high-sensitivity detector (12), the small-capacity variable-capacity container (4) + the large-capacity burette (20) + the low-sensitivity detector (13), and the small-capacity variable-capacity container (4) + the small-capacity burette (21) + the low-sensitivity detector (13) are detected, and the comprehensive value is set as S, S = 0.4S1 + 0.25S2 + 0.2S3 + 0.15S4.

10. The method of monitoring dissolved gases in oil of a load tap changer according to claim 8, characterized in that: The optimal combination configuration result obtained in S5 is stored in a historical database for parameter matching next time.

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