A method and apparatus for laser digital detection of gas in a transformer.
By installing transparent pipes and laser emitters and receivers at specific locations on the transformer, the changes in laser brightness during the circulation of insulating oil are monitored. Combined with flow rate, voltage, and temperature, the problem of accidents caused by failure to detect gas before transformer commissioning is solved, and fault prediction and safe commissioning are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHONGWEI POWER SUPPLY COMPANY OF STATE GRID NINGXIA ELECTRIC POWER
- Filing Date
- 2023-08-04
- Publication Date
- 2026-05-26
AI Technical Summary
In the existing technology, the gas in the insulating oil of the transformer is not fully detected before it is put into operation, which may lead to discharge accidents after the transformer is put into operation.
A laser digital detection method is adopted, which involves installing a transparent pipe and a laser emitter and receiver at a specific location on the transformer to monitor the changes in laser brightness during the circulation of insulating oil. Combined with flow rate, voltage rise rate and temperature, fault values are calculated to predict whether gas will cause a fault.
It enables accurate monitoring of air bubbles in insulating oil before transformer commissioning, predicts whether a fault will occur, and avoids breakdown accidents caused by air bubbles during commissioning.
Smart Images
Figure CN117055126B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of transformer technology, and in particular to a method and apparatus for laser digital detection of gases in transformers. Background Technology
[0002] Oil-immersed transformers are commonly found in power grid equipment. Before being put into operation, they require a long period of hot oil circulation and cooling to ensure that air bubbles are not generated in the insulating oil during the injection process. This process removes the gas from the insulating oil.
[0003] Before a transformer is put into operation, relying solely on this method still has many drawbacks. For example, even if the above-mentioned venting process is implemented, it may not be possible to guarantee that the insulating oil is free of any air bubbles. In other cases, since the transformer cooler also contains air, if the hot oil circulation process was not carried out before operation, the gas in the cooler will be integrated into the insulating oil after direct operation, resulting in a floating potential and causing a discharge accident.
[0004] In existing technologies, there are instances where the gas in the insulating oil is not adequately checked before commissioning, leading to accidents after commissioning. Summary of the Invention
[0005] This invention provides a method and device for laser digital detection of gases in transformers, to solve the problem that accidents occur when transformers are put into operation before sufficient gas detection in the insulating oil.
[0006] In a first aspect, a method for laser digital detection of gas in a transformer is provided, comprising:
[0007] Replace at least a portion of the pipes at a specific location on the transformer with transparent pipes, wherein the specific location includes at least one of the following: oil inlet, oil pump, and oil tank connection.
[0008] Multiple laser emitters and receivers are evenly spaced on the outer surface of the sidewall of the transparent pipe. Each laser emitter and receiver is located on the circumference of the same circular cross-section perpendicular to the central axis of the transparent pipe. The emitting end and receiving end of each laser emitter and receiver are located on the diameter of the circular cross-section.
[0009] Before the transformer is put into operation, the insulating oil circulation in the transformer is started;
[0010] During the circulation of insulating oil, the transmitting end of each laser transmitter and receiver emits a laser, so that the receiving end of each laser transmitter and receiver receives the laser emitted by the corresponding transmitting end;
[0011] Obtain the difference between the brightness of the laser emitted by the transmitting end of each laser transmitter and receiver and the brightness of the laser received by the corresponding receiving end;
[0012] If the difference in brightness of the laser corresponding to at least one of the laser emitters and receivers is greater than a preset threshold, then detection data within a detection cycle is acquired, wherein the detection data includes: the first flow rate of transformer oil, the first rate of rise of voltage applied to transformer oil through the needle plate electrode, the first rate of change of brightness detected by the receiving end of the laser emitter and receiver, and the first average temperature of transformer oil.
[0013] Based on the detection data, the fault value corresponding to the detection data is calculated according to a predetermined functional relationship;
[0014] Based on the relationship between the fault value and the fault threshold, it is predicted whether the gas in the transformer oil will cause the transformer fault.
[0015] In a second aspect, an apparatus for laser digital detection of gas in a transformer is provided, comprising: a processor for performing the method for laser digital detection of gas in a transformer as described in the first aspect embodiment.
[0016] Thus, in this embodiment of the invention, the presence of air bubbles in the insulating oil can be determined based on the change in laser brightness. This can simulate whether the transformer insulating oil will carry air from the equipment under voltage fluctuations, thereby accurately detecting air bubbles before commissioning. This allows for prediction of whether the transformer will fail during commissioning, and thus determines whether to continue commissioning the transformer, avoiding accidents caused by air bubbles during commissioning that could lead to transformer breakdown. Attached Figure Description
[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a flowchart of a method for laser digital detection of gas in a transformer according to an embodiment of the present invention. Detailed Implementation
[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] This invention discloses a method for laser digital detection of gases in a transformer. For example... Figure 1 As shown, the method of this embodiment of the invention includes the following steps:
[0021] Step S101: Replace at least a portion of the conduit at a specific location on the transformer with a transparent conduit.
[0022] The specific locations include at least one of the following: oil inlet, oil pump, and oil tank connection. These locations are not only representative, but also make pipeline replacement easier and facilitate subsequent testing.
[0023] Replacing the tube with a transparent one facilitates subsequent laser brightness detection. Depending on the actual project complexity, only a portion or all of the tubes can be replaced.
[0024] Step S102: Multiple laser emitters and receivers are evenly spaced on the outer surface of the sidewall of the transparent pipe.
[0025] Multiple laser emitters and receivers are located on the circumference of a circular cross-section perpendicular to the central axis of the transparent pipe. The emitting and receiving ends of each laser emitter and receiver are located on the diameter of the circular cross-section. This ensures that as many air bubbles as possible flowing through that circular cross-section are missed. The specific location of this circular cross-section can be determined empirically, and could be the beginning, middle, or end of the transparent pipe, etc. The emitting and receiving ends of the laser emitters and receivers can be mounted on the outer surface of the sidewall of the transparent pipe using conventional mechanical fixing methods such as brackets.
[0026] Step S103: Before putting the transformer into operation, start the circulation of insulating oil in the transformer.
[0027] Step S104: During the circulation of insulating oil, the transmitting end of each laser transmitter and receiver emits a laser, so that the receiving end of each laser transmitter and receiver receives the laser emitted by the corresponding transmitting end.
[0028] Step S105: Obtain the difference between the brightness of the laser emitted by the transmitter and the brightness of the laser received by the receiver at each laser transmitter and receiver.
[0029] When the transmitter emits a laser, the brightness of the emitted laser can be preset. After the receiver receives the laser, it can collect the brightness of the received laser and thus calculate the difference in brightness.
[0030] Step S106: If the difference in brightness of the laser corresponding to at least one laser emitter and receiver is greater than a preset threshold, then acquire the detection data within a detection cycle.
[0031] When the emitted laser encounters a bubble, the reflection from the bubble causes partial reflection, resulting in a decrease in the brightness of the received laser compared to the case where there are no bubbles in the transformer oil. When the brightness decreases to a certain level, it indicates the possible presence of a large number of bubbles in the transformer oil, requiring further, more accurate detection. Therefore, to minimize the risk of malfunctions caused by bubbles in the transformer oil after the transformer is put into operation, in this embodiment of the invention, if the difference in brightness between the lasers emitted and received by at least one laser on the same circumference exceeds a preset threshold, further detection is required.
[0032] Specifically, the detection data includes: the first flow rate of the transformer oil, the first rate of increase of the voltage applied to the transformer oil through the needle plate electrode, the first rate of change of brightness detected by the receiving end of the laser emitter receiver, and the first average temperature of the transformer oil.
[0033] The transformer oil flow rate is the quotient of the transformer oil throughput within one testing cycle and the testing cycle itself, i.e., Q = ΔQ / T, where Q represents the transformer oil flow rate within one testing cycle, ΔQ represents the transformer oil throughput within one testing cycle (obtainable via a flow meter), and T represents the testing cycle. The duration of the testing cycle can be set empirically.
[0034] The first rate of increase of the voltage applied to the transformer oil through the needle plate electrode is the quotient of the voltage increase value within one cycle and the detection cycle, i.e., V = ΔV / T, where V represents the first rate of increase of the voltage applied to the transformer oil through the needle plate electrode, and ΔV represents the voltage increase value applied to the transformer oil through the needle plate electrode within one detection cycle. T -V0, V T V0 represents the voltage applied to the transformer oil through the needle plate electrode at the end of the detection cycle, while V0 represents the voltage applied to the transformer oil through the needle plate electrode at the beginning of the detection cycle.
[0035] The first rate of change of brightness detected by the receiver of the laser emitter-receiver is the quotient of the change in brightness detected by the receiver within one detection period and the detection period, i.e., L = (L T -L0) / T,L TL0 represents the minimum brightness detected by the laser transmitter receiver at the end of the detection cycle, and L0 represents the maximum brightness detected by the laser transmitter receiver at the beginning of the detection cycle. Since there are multiple receivers, multiple brightness levels will be collected. Therefore, the minimum brightness is selected at the end of the detection cycle, and the maximum brightness is selected at the beginning of the detection cycle for calculation.
[0036] The first average temperature of the transformer oil is the average temperature of the transformer oil at the beginning and end of a detection cycle.
[0037] It should be understood that the terms "first," "second," etc., used in the embodiments of the present invention are for distinction purposes only and have no practical significance.
[0038] During the flow of transformer oil, bubbles may merge, forming larger bubbles from smaller ones. This process is related to the flow rate of the transformer oil, the voltage applied to the transformer oil through the needle plate electrodes, and the temperature of the transformer oil. Therefore, in addition to changes in brightness, the aforementioned detection data needs to be collected to further determine whether bubbles in the transformer oil will cause transformer failure.
[0039] Step S107: Based on the detection data, calculate the fault value corresponding to the detection data according to a predetermined functional relationship.
[0040] Specifically, the functional relationship includes: G = a T *Q+b T *V+c T *L.
[0041] Where G represents the fault value, Q represents the transformer oil flow rate within one detection cycle, and a T The first weight represents the average temperature of the transformer oil within a detection cycle, V represents the rate of rise of the voltage applied to the transformer oil through the needle plate electrode within a detection cycle, and b T The second weight represents the average temperature of the transformer oil within a detection cycle, L represents the rate of change of brightness detected by the receiver of the laser emitter-receiver within a detection cycle, and c represents the second weight. T This represents the third weighting of the average temperature of the transformer oil within a testing cycle.
[0042] The influence of transformer oil flow rate and temperature on the generation and changes of bubbles is complex, and changes in bubbles directly lead to changes in the collected brightness. Through repeated and extensive experiments and creative efforts, the inventors summarized the above-mentioned functional relationship, which can more accurately reflect the relationship between these factors and bubbles in transformer oil, thereby enabling more accurate prediction of whether transformer failures will occur.
[0043] Specifically, this step includes the following process:
[0044] 1. Query the preset temperature-weight correspondence table to obtain the first weight, second weight and third weight corresponding to the first average temperature.
[0045] The first, second, and third weights are related to the average temperature of the transformer oil; therefore, the corresponding weights for the average temperature are obtained in advance. The design, where weights change with transformer oil temperature, allows for more accurate subsequent judgments. The temperature-weight correspondence table is a pre-set table based on experience.
[0046] 2. Using the obtained first weight, second weight, and third weight, as well as the first flow rate, first rise rate, and first change rate, the fault value is calculated according to the functional relationship.
[0047] By substituting the collected detection data and the obtained weights into the above functional relationship, the fault value corresponding to the detection data can be calculated.
[0048] Step S108: Based on the relationship between the fault value and the fault threshold, predict whether the gas in the transformer oil will cause a transformer fault.
[0049] The fault threshold can be obtained through the following process:
[0050] 1. When gas in the transformer oil causes a transformer fault, obtain the second flow rate of the transformer oil within a detection cycle, the second rate of rise of the voltage applied to the transformer oil through the needle plate electrode, the second rate of change of brightness detected by the receiving end of the laser emission receiver, and the second average temperature of the transformer oil.
[0051] 2. Query the preset temperature-weight correspondence table to obtain the first weight, second weight and third weight of the transformer oil at the second average temperature.
[0052] 3. Based on the functional relationship, using the second flow rate, second rate of increase, second rate of change, first weight, second weight, and third weight at the second average temperature, calculate the fault value at the second average temperature of the transformer oil, which is used as the fault threshold at the second average temperature.
[0053] Through the above steps, the corresponding physical quantities of the transformer fault caused by the gas in the transformer oil at the second average temperature were collected. Thus, the fault threshold when the transformer fault is caused by the gas in the transformer oil at the second average temperature can be calculated, which can be used as the basis for judging whether the transformer is faulty.
[0054] Specifically, the results of this step can be one of the following two:
[0055] 1. If the fault value at the average temperature of the same transformer oil is greater than the fault threshold, it is predicted that the transformer will fail.
[0056] This indicates that there is still a large amount of gas in the transformer oil. If the transformer is put into use at this time, the excessive gas will create floating potentials and cause a discharge accident. Therefore, the insulating oil in the transformer should be vented by circulating the insulating oil until the fault value at the same transformer oil average temperature does not exceed the fault threshold.
[0057] 2. If the fault value at the average temperature of the same transformer oil is not greater than the fault threshold, it is predicted that the transformer will not fail.
[0058] In this situation, it indicates that the gas in the insulating oil has been largely expelled, the transformer meets the operating conditions, and there will be no discharge accident caused by excessive gas forming a floating potential. At this point, the circulation of the insulating oil in the transformer can be stopped, there is no need to vent further, and the transformer will not fail when put into operation.
[0059] Furthermore, embodiments of the present invention also provide a device for laser digital detection of gas in a transformer, comprising: a processor for performing the method for laser digital detection of gas in a transformer as described in the above embodiments.
[0060] In summary, the embodiments of the present invention can determine whether there are air bubbles in the insulating oil based on the brightness change of the laser. It can simulate whether the transformer insulating oil will carry air from the equipment under voltage fluctuations, so as to accurately detect air bubbles before commissioning, predict whether the transformer will fail, and determine whether to continue commissioning the transformer. This avoids the accident of transformer breakdown caused by air bubbles during commissioning.
[0061] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A method for laser digital detection of gas in a transformer, characterized in that, include: Replace at least a portion of the pipes at a specific location on the transformer with transparent pipes, wherein the specific location includes at least one of the following: oil inlet, oil pump, and oil tank connection. Multiple laser emitters and receivers are evenly spaced on the outer surface of the sidewall of the transparent pipe. Each laser emitter and receiver is located on the circumference of the same circular cross-section perpendicular to the central axis of the transparent pipe. The emitting end and receiving end of each laser emitter and receiver are located on the diameter of the circular cross-section. Before the transformer is put into operation, the insulating oil circulation in the transformer is started; During the circulation of insulating oil, the transmitting end of each laser transmitter and receiver emits a laser, so that the receiving end of each laser transmitter and receiver receives the laser emitted by the corresponding transmitting end; Obtain the difference between the brightness of the laser emitted by the transmitting end of each laser transmitter and receiver and the brightness of the laser received by the corresponding receiving end; If the difference in brightness of the laser corresponding to at least one of the laser emitters and receivers is greater than a preset threshold, then detection data within a detection cycle is acquired, wherein the detection data includes: the first flow rate of transformer oil, the first rate of rise of voltage applied to transformer oil through the needle plate electrode, the first rate of change of brightness detected by the receiving end of the laser emitter and receiver, and the first average temperature of transformer oil. Based on the detection data, the fault value corresponding to the detection data is calculated according to a predetermined functional relationship; Based on the relationship between the fault value and the fault threshold, it is predicted whether the gas in the transformer oil will cause the transformer fault.
2. The method for laser digital detection of gas in a transformer according to claim 1, characterized in that, The functional relationship includes: G = a T * Q + b T * V + c T * L ; in, G Indicates the fault value. Q This indicates the flow rate of transformer oil within one monitoring cycle. a T The first weight represents the average temperature of the transformer oil within a detection cycle. V This indicates the rate of increase of the voltage applied to the transformer oil through the needle plate electrodes within one detection cycle. b T The second weight represents the average temperature of the transformer oil within a detection cycle. L This represents the rate of change in brightness detected by the receiver of the laser emitter / receiver within one detection period. c T This represents the third weighting of the average temperature of the transformer oil within a testing cycle.
3. The method for laser digital detection of gas in a transformer according to claim 2, characterized in that, Also includes: When gas in the transformer oil causes a transformer fault, the system obtains the second flow rate of the transformer oil within a detection cycle, the second rate of rise of the voltage applied to the transformer oil through the needle plate electrode, the second rate of change of brightness detected by the receiving end of the laser emission receiver, and the second average temperature of the transformer oil. Query the preset temperature-weight correspondence table to obtain the first weight, the second weight, and the third weight of the transformer oil at the second average temperature; Based on the functional relationship, the fault value at the second average temperature of the transformer oil is calculated using the second flow rate, the second rate of increase, the second rate of change, the first weight, the second weight, and the third weight at the second average temperature, and is used as the fault threshold at the second average temperature.
4. The method for laser digital detection of gas in a transformer according to claim 3, characterized in that, The step of calculating the fault value corresponding to the detection data includes: Query the preset temperature-weight correspondence table to obtain the first weight, the second weight, and the third weight corresponding to the first average temperature; Using the acquired first weight, second weight, and third weight, as well as the first flow rate, first rise rate, and first change rate, the fault value is calculated according to the functional relationship.
5. The method for laser digital detection of gas in a transformer according to claim 3, characterized in that, The step of predicting whether the gas in the transformer oil will cause the transformer failure includes: If the fault value at the average temperature of the same transformer oil is greater than the fault threshold, then the transformer is predicted to fail. If the fault value at the average temperature of the same transformer oil is not greater than the fault threshold, then it is predicted that the transformer will not fail.
6. The method for laser digital detection of gas in a transformer according to claim 2, characterized in that, The formula for calculating the rate of change of brightness detected by the receiving end of the laser emitter / receiver within one detection cycle includes: L =( L T - L 0) / T； in, L T This represents the minimum brightness detected by the laser transmitter and receiver at the end of the detection cycle. L 0 represents the maximum brightness detected by the laser transmitter receiver at the start of the detection period, and T represents the detection period.
7. A device for laser digital detection of gas in a transformer, characterized in that, include: A processor for performing the laser digital detection of gas in a transformer as described in any one of claims 1 to 6.
Citation Information
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