JPH0794334A - Deterioration diagnostic system and life predictive system of oil-immersed transformer - Google Patents

Abstract

PURPOSE:To provide a system which is capable of easily diagnosing or predicting the current deterioration state or the life expectancy of an oil-immersed transformer at a low cost. CONSTITUTION:A gas quantity analyzer 2 measures the volume of prescribed gas component contained in insulating oil which is regularly or irregularly sampled from oil-immersed transformers 11 to 1n. A data processing device 3 estimates a variation range of dissolved gas quantity in a normal operation through a probability method basing on the past data of measured dissolved gas quantity, and the measurement result of current dissolved gas quantity is compared with the estimated variation range of dissolved gas quantity, whereby it is judged that the oil-immersed transformers 11 to 1n operate normally or not. When it is judged that the oil-immersed transformers 11 to 1n operate normally, the average polymerization degree retention rate of the insulating papers in the oil-immersed transformers 11 to 1n is calculated basing on time measurement results of the current dissolved gas quantity. Basing on a change in dissolved gas quantity with time, a time (termination of life) when a dissolved gas quantity reaches to a previously determined threshold value is predicted by calculation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for diagnosing a deteriorated state of an oil-filled transformer and predicting its future life based on the amount of a predetermined gas dissolved in insulating oil.

[0002]

2. Description of the Related Art An oil-filled transformer is an outer box filled with insulating oil (mineral oil, synthetic oil, etc.) containing a main body (structures such as an iron core and windings). Since it has a high cooling effect, it is used in most large capacity transformers. By the way, it is widely known that the life of such an oil-filled transformer greatly depends on the degree of deterioration of the insulating paper (kraft paper) wound around the winding. That is, when the mechanical strength of this insulating paper drops below a predetermined value,
Oil-filled transformers often run out of life.

In general, the mechanical strength of insulating paper can be determined by the tensile strength and the average residual polymerization degree.
Insulation paper was actually taken from the oil-filled transformer, and its tensile strength and average residual polymerization degree were measured.

[0004]

However, in order to collect the insulating paper, the operation of the oil-filled transformer must be temporarily stopped, which causes a problem of blackout. Further, in order to collect the insulating paper, the internal structure of the oil-filled transformer must be lifted by a crane or the like, which is a troublesome work, and there is a problem that the work cost is high. Further, there is a problem in that the portion where the insulating paper is taken must be repaired later.

Therefore, an object of the present invention is to provide a system capable of easily and inexpensively diagnosing the current deterioration state of an oil-filled transformer.

Another object of the present invention is to provide a system which can easily and inexpensively predict the future life of the oil-filled transformer.

[0007]

The invention according to claim 1 is
A system for diagnosing the deterioration state of an oil-filled transformer based on the amount of dissolved gas in insulating oil measured in a time series, and assuming that the oil-filled transformer is operating normally, A variation range estimation means that stochastically estimates the variation range of the current dissolved gas amount from past measurement data of the dissolved gas amount, by comparing the measurement result of the current dissolved gas amount with the estimated variation range. , A determining means for determining whether the oil-filled transformer is operating normally, and when the determining means determines the normal operation of the oil-filled transformer, based on the measurement result of the current dissolved gas amount, An average polymerization degree residual rate calculating means for calculating an average polymerization degree residual rate of the insulating paper in the oil-filled transformer is provided.

According to a second aspect of the present invention, in the first aspect of the invention, the determining means determines whether the current dissolved gas amount measurement result is within the fluctuation range estimated by the fluctuation range estimating means. If it is determined that the input transformer is operating normally and the measurement result of the current dissolved gas amount exceeds the upper limit of the fluctuation range estimated by the fluctuation range estimation means, the oil-filled transformer has failed. Or it is determined that the measurement result has an error exceeding the permissible limit, and the current measurement result of the dissolved gas amount is below the fluctuation range estimated by the fluctuation range estimation means, the measurement concerned. It is characterized in that it is determined that an error exceeding the allowable limit has occurred in the result.

The invention according to claim 3 is the invention according to claim 1 or 2.
Invention, the CO gas and CO ₂ dissolved in the insulating oil
The deterioration state of the oil-filled transformer is diagnosed based on the amount of gas.

According to a fourth aspect of the present invention, there is provided a system for predicting the life of an oil-filled transformer based on the amount of dissolved gas in insulating oil measured in a time series. Assuming that the engine is operating, the fluctuation range estimation means that stochastically estimates the fluctuation range of the current dissolved gas amount from the past measurement data of the dissolved gas amount, and the measurement result of the current dissolved gas amount. By comparing the fluctuation range
Judgment means for judging whether the oil-filled transformer is operating normally, and when the judgment means determines the normal operation of the oil-filled transformer, based on the change with time of the dissolved gas amount to the present, A predictive calculation unit is provided for predicting and calculating a time when the dissolved gas amount reaches a predetermined threshold value as a life reaching time.

According to a fifth aspect of the invention, in the fourth aspect of the invention, the life of the oil-filled transformer is predicted based on the amounts of CO gas and CO ₂ gas dissolved in the insulating oil. To do.

[0012]

In the invention according to claim 1, the variation range of the dissolved gas amount during normal operation is stochastically estimated based on the past measurement data of the dissolved gas amount in the insulating oil, and the present dissolved gas amount is calculated. It is determined whether the oil-filled transformer is operating normally by comparing the measurement result of 1. with the estimated fluctuation range. Then, when it is determined that the oil-filled transformer is operating normally, the average polymerization degree residual ratio of the insulating paper in the oil-filled transformer is calculated based on the current measurement result of the dissolved gas amount. I have to. The average residual polymerization degree of the insulating paper obtained by the calculation is used as an index indicating the deterioration state of the oil-filled transformer.

According to the second aspect of the present invention, it is determined whether the current measurement result of the dissolved gas amount is within the fluctuation range estimated by the fluctuation range estimating means, is protruding to the upper side, or is protruding to the lower side. We conduct a detailed examination of the condition of the oil-filled transformer in each case.

In the invention according to claim 4, the variation range of the dissolved gas amount during normal operation is stochastically estimated based on the past measurement data of the dissolved gas amount in the insulating oil, and the present dissolved gas amount is calculated. It is determined whether the oil-filled transformer is operating normally by comparing the measurement result of 1. with the estimated fluctuation range. Then, when it is determined that the oil-filled transformer is operating normally, the timing at which the dissolved gas amount reaches a predetermined threshold value is predicted based on the change over time of the dissolved gas amount to the present. I am trying to calculate. The threshold reaching time obtained by the prediction calculation indicates the approximate life reaching time of the oil-filled transformer.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of one embodiment of the present invention described later will be explained. When the oil-filled transformer is operating normally, the insulating paper is decomposed at low temperature and carbon monoxide and carbon dioxide (C
O + CO ₂ ) is generated. The generated CO + CO ₂ is dissolved in insulating oil. Therefore, it is considered that by analyzing the amount of CO + CO ₂ dissolved in the insulating oil, it is possible to estimate the current deterioration state of the insulating paper and the progress of the deterioration in the future. Therefore, the inventor of the present application investigated past measurement data disclosed in various documents, and further measured 100 oil-filled transformers. As a result, the average residual degree of polymerization of the insulating paper and the CO + CO dissolved in the insulating oil
It was found that there was a correlation between the _two .

FIG. 2 is a graph showing the correlation between the average residual degree of polymerization of insulating paper and CO + CO ₂ dissolved in insulating oil, which was obtained by examining past measurement data. . In FIG. 2, the horizontal axis represents C per 1 g of insulating paper.
The volume amount of O + CO ₂ (unit: ml / g) is shown on a logarithmic scale, and the vertical axis shows the average degree of polymerization residual rate (%) on an even scale. It is generally said that when the average residual polymerization degree is 20% to 30%, the mechanical strength of the insulating paper is lost.
In fact, 40% to 60% can be said to be the life of the oil-filled transformer.
From the graph in Fig. 2, the volume of CO + CO ₂ is equal to that of the insulating paper 1.
It can be seen that when the amount is 1 ml (milliliter) with respect to g, the average polymerization degree residual rate becomes 60%.

The inventor of the present application converts the horizontal axis of the graph of FIG. 2 from a logarithmic scale to a uniform scale and further considers the measurement data obtained for 100 oil-immersed transformers to show the correlation shown in FIG. Created a relationship graph. In FIG. 3, the change curve A
Is the average residual polymerization degree of insulating paper and CO for 1 g of insulating paper.
The cubic function curve approximating the correlation with the volume of + CO ₂ is shown. Further, in FIG. 3, the change curve B shows a quadratic function curve that approximates the correlation shown in FIG. As is clear from FIG. 3, the average polymerization degree residual ratio is 6
It can be seen that the cubic function curve A is closer to the above correlation than the quadratic function curve B in the vicinity of 0% to 40%.

Now, x is CO + CO ₂ for 1 g of insulating paper
Volume ratio (ml / g), and y is the average degree of polymerization residual rate (%)
Then, the cubic function curve A in FIG. 3 is represented by y = a · x ³ + b · x ² + c · x + d (1). Then, when each coefficient of the above equation (1) is obtained based on the past measurement data and the newly measured data, a = −2.06 b = 17.99 c = −56.52 d = 98.00 Became. Therefore, the above equation (1) becomes ^{y = -2.06x 3 + 17.99x 2 -56.52x} + 98.00 ... (2).

Therefore, in the embodiment described below, the current average polymerization degree residual ratio of the insulating paper is indirectly calculated using the above equation (2) to indicate the current deterioration state of the oil-filled transformer. In addition to using as an index, the time when the volume of CO + CO ₂ per 1 g of insulating paper reaches 1 ml, that is, the average residual degree of polymerization is 6
We are trying to predict when the oil-filled transformer will reach the end of its useful life by reaching 0%.

If a failure occurs in the oil-filled transformer for some reason and a short circuit or partial discharge occurs inside the transformer, the insulating paper is decomposed at a high temperature and a large amount of CO and CO ₂ is produced. Therefore, if the above-mentioned deterioration diagnosis method and life prediction method are directly applied to the oil-filled transformer, there will be no problem during normal operation of the oil-filled transformer, but accurate diagnosis and life prediction cannot be performed when a failure occurs. . Therefore, in the embodiment described below, it is determined whether the current oil-filled transformer is in a normal operating state from the past measurement data of dissolved CO + CO ₂ amount, the dissolved CO + CO ₂ amount only when it is in normal operating conditions Based on the above, the current deterioration state and the future life expiration time are calculated.

FIG. 1 is a block diagram showing the configuration of an oil-filled transformer diagnosis and life prediction system according to an embodiment of the present invention. In FIG. 1, a gas amount analyzer 2 is composed of a gas chromatography device, a simple analyzer of air bubbling system, etc., analyzes the insulating oil sampled from each oil-filled transformer 11 to 1n, and analyzes the insulating oil in the insulating oil. The amount of a predetermined gas component dissolved in the is detected. The analysis result of the gas amount analyzer 2 is given to the data processing device 3. The data processing device 3 is composed of a personal computer, a microcomputer, or the like, and calculates the deterioration state and the end of life of the oil-filled transformer based on the analysis result of the gas amount analyzer 2. The calculation result of the data processing device 3 is output to the display device 4 and the printer 5, where it is displayed and printed. A database storage device 6 is connected to the data processing device 3. The database storage device 6 stores various data regarding the oil-filled transformers 11 to 1n.

Next, the operation of the above embodiment will be described with reference to FIGS. 4 and 5. First, in step S1 of FIG. 4, a predetermined amount of insulating oil (amount required for analysis work in the gas analyzer 2; about 50 cc) is sampled from any one of the oil-filled transformers 11 to 1n. It At this time, it is necessary to take care not to collect the remaining insulating oil without causing heat convection in the lower part of the oil-filled transformer. This is because such residual oil does not convectively move in the transformer, and thus the gas generated due to the deterioration of the insulating paper is difficult to melt.

Next, the gas amount analyzer 2 expels and separates dissolved gas components from the insulating oil by vacuum degassing or air bubbling the insulating oil sampled in step S1, and the separated gas is separated. The composition and amount of the components are analyzed (step S2). Thereby, the dissolved amount of the target gas (volume amount of gas component dissolved in insulating oil per unit volume) is detected. In the present embodiment, the gas amount analyzer 2 uses carbon monoxide (CO), carbon dioxide (CO ₂ ), hydrogen (H ₂ ), methane (CH ₄ ), acetylene (C ₂ H ₂ ), ethylene ( C ₂ H ₄ ), ethane (C ₂ H ₆ ), propylene (C ₃ H ₆ ), propane (C
₃ H ₈ ) etc. are detected. The dissolved gas amount detected by the gas amount analyzer 2 is shown in the unit of ppm, for example.

Next, the number of the oil-filled transformer to be diagnosed this time, that is, the number of the oil-filled transformer from which the insulating oil was sampled in step S1 is designated (step S).
3). This designation is made by the operator operating an input device (not shown) such as a keyboard attached to the data processing device 3. When the oil-filled transformer number is designated, the data processing device 3 reads the data file of the corresponding oil-filled transformer from the database storage device 6 (step S4). This data file contains various data (capacity, rated voltage, date of manufacture, serial number, manufacturer, etc.) of various data related to the corresponding oil-filled transformer, and past measurements of the dissolved amount of each target gas. Data, data of date and time when insulating oil was sampled, etc. are stored.

Next, the data processing device 3 uses the gas amount analyzer 2 to determine the dissolved amount of each target gas measured in step S2.
Is input (step S5). Next, the data processing device 3 compares the dissolved amount of each target gas input in step S5 with a predetermined threshold value for each target gas to determine the current state of the transformer (step S6). ).
If the dissolved amount of even one of the plurality of target gases exceeds a predetermined threshold value, the data processing device 3 determines that the oil-filled transformer has a serious abnormality. To do. Next, the data processing device 3 performs the above step S6.
The determination result and the dissolved amount of each target gas input in step S5 are registered in the data file read in step S4 (step S7).

Next, the data processing device 3 creates a transition forecast graph of the dissolved CO + CO ₂ amount during normal operation from the measured data of the past dissolved CO + CO ₂ amount (for example, up to the previous time), and this transition forecast graph This time dissolved CO + C
The measurement result of the O ₂ amount is compared (step S8). The method of creating this transition prediction graph will be described below.

When the operating condition of the oil-filled transformer is normal, the transition of the amount of dissolved CO + CO ₂ is as follows: time x, dissolved CO + CO
It is empirically known that the linear function y = ax + b is substantially obeyed when y is a quantity of _two .

Now, assuming that the amount of dissolved CO + CO ₂ changes with time as shown in FIG. 6, the coefficients a and b will be determined by the least squares method. here,

[Equation 1] Then, the coefficients a and b can be obtained by solving the following simultaneous equations (3).

[Equation 2]

[0029] by solving the above equation (3), coefficients a, when determining the b, a = (u-Nb ) / S b = (tu-Sv) / (tN-S 2) , and the linear function y = ax + b Is given by the following equation (4). y = {(u-Nb) / S} x + {(tu-Sv) / (tN-S 2)} ... (4)

If the above equation (4) is used, future dissolved CO +
The change in the amount of CO ₂ can be predicted. However, due to the influence of various factors, the dissolved CO + CO ₂ amount for going remained uncertain manner, in the present embodiment considered to continue to trend with the range there are dissolved CO + CO ₂ amount. That is, the coefficient b is considered to have a standard deviation σ _b . Further, the coefficient a indicates the speed (gradient) of the future transition and is important for predicting the life, so this is also the standard deviation σ.
Think of it as having _a .

[0031] As described later, in the present embodiment, the standard deviation sigma _a, sigma _b a, "a by the least squares method by adding a random number to the measured value, obtaining a b" sufficiently large number of times trial of (e.g., 100 times) and decide to ask. This method is just an example, and the standard deviation σ
You may ask for _a and σ _b .

Next, how to obtain the standard deviations σ _a and σ _b by such a method will be described. Now, a linear function showing the transition of the dissolved CO + CO ₂ amount obtained by the least squares method from the measured data of the dissolved CO + CO ₂ amount in the past is y = ax
+ B Then, y _{i (j)} is obtained by calculating the following equation (5). y _{i (j)} = ax _i + b + r _{i (j)} (5) In the above equation (5), i = 0, 1, ..., N-1
Is. In addition, r _{i (j)} is a random number that follows a normal distribution and has a mean of 0 and the same standard deviation as the measured value. Also, j =
, M−1 (M indicates the number of trials, for example, 100). Further, x _i is the actual measurement date.

Next, the coefficients a _(j) and b _(j) are obtained from x _i and y _{i (j)} by the method of least squares. This is tried M times, and standard deviations σ _a and σ _b are obtained from the following equations (6) and (7), respectively.

[Equation 3]

Assuming that the straight line on which the amount of dissolved CO + CO ₂ changes in the future is y = a'x + b ', the coefficient a' (or b ') is between a-kσ _a and a + kσ _a (or b-kσ _b to b + kσ). _b )), in other words, assuming that the transformer is operating normally, the amount of dissolved CO + CO ₂ is the first straight line: y = ax + b + kσ _b + kσ _a (x−
x _N-1 ) Second straight line: y = ax + b−kσ _b −kσ _a (x−
x _N-1 ), the probability of transition within the region is about 68.3% when k = 1, about 95.4% when k = 2, and about 99.7% when k = 3. The first straight line is the straight line α in FIG. 6, and the second straight line is the straight line β in FIG. Also,
x _N-1 is the previous measurement value.

Next, the data processing device 3 carries out step S8.
As a result of the comparison at this time, this time dissolved CO + CO₂Amount measurement result
Is a region between the first straight line α and the second straight line β (the region in FIG. 6).
) Inside (step S)
9). This time dissolved CO + CO₂The measurement result of the amount is
If it is in the area, the transformer is operating normally
Since the possibility is extremely high, the data processing device 3 first
O and CO₂Ratio with (CO / CO₂) Is calculated (step
S10). Next, the data processing device 3 uses CO / CO ₂
Judge whether or not exceeds a predetermined value (eg 0.2)
Yes (step S11). CO / CO₂Is 0.2 or more
In this case, the data processing device 3 determines that the transformer is out of order.
And execute a failure process described later. On the other hand, CO / CO
₂Is less than 0.2, the data processing device 3 is
Judge that it is operating normally and execute normal processing.

On the other hand, when it is determined in step S9 that the measurement result of the amount of dissolved CO + CO ₂ this time does not fall within the above range, that is, the area above the first straight line α (area in FIG. 6). Alternatively, when it is determined that the area is below the second straight line β (area in FIG. 6),
The data processing device 3 causes the operator to again sample the insulating oil and analyze it (step S9a).
Then, the data processing device 3 determines again whether or not the dissolved CO + CO ₂ amount in the second measurement result is out of the range of the region (step S12). When the amount of dissolved CO + CO ₂ in the second measurement result is within the range, the data processing device 3 determines that the first measurement result has an error of the allowable value or more, and based on the second measurement result. The operation after step S10 is executed. on the other hand,
When the amount of dissolved CO + CO _{2 in the} second measurement result is out of the range of the region as in the case of the first measurement result, the data processing device 3 determines that the transformer has a failure and performs the failure treatment. Run.

Next, referring to FIG. 5, in the above normal processing
The operation will be described. First, the data processing device 3
Temperature correction is performed (step S13). Because CO
And CO₂Is easily absorbed by insulating paper at low temperatures, but 80
This is because if the temperature exceeds ℃, it will not be adsorbed. here
Is calculated by using the following equations (8) and (9).
₂Is corrected to the volume at 80 ° C. M (CO) = M₁Xexp [560 {(1 / T) -0.0028}] (8) M (CO₂) = M₂Xexp [2260 {(1 / T) -0.0028}] (9) In the above equations (8) and (9), M₁Is at temperature t ° C
Is the volume of CO, M ₂Is CO at temperature t ° C₂Volume of
Is the amount. Further, T is an absolute temperature (273 + t ° C.)
It From the above formulas (8) and (9), CO + CO₂80 ℃
The volume of time is M (CO) + M (CO₂).

Next, the data processing device 3 calculates the volume amount (ml / g) of CO + CO ₂ with respect to 1 g of the insulating paper (step S14). That is, the volume M of CO + CO ₂ detected from the sampled oil and temperature-corrected
By converting (CO) + M (CO ₂ ) into a volume amount with respect to the total oil amount and dividing the converted volume amount by the total weight of the insulating paper, the volume amount of CO + CO ₂ per 1 g of the insulating paper is obtained. Next, the data processing device 3 performs step S
The volume amount of CO + CO ₂ with respect to 1 g of the insulating paper obtained in 13 is substituted into the above-mentioned formula (2), and the current average degree of polymerization residual ratio of the insulating paper is calculated (step S15).

Next, the data processing device 3 calculates the end of life of the transformer (step S16). This operation is
Is performed on the basis of the first linear equation _{y = ax + b + kσ b} + kσ a (x-x N-1) the following equation obtained by modifying the above-described (10). x _L = - Note _{{y L (b + kσ b} -kσ a x N-1)} / (a + kσ a) ... (10), In the above equation (10), x _L is the arrival time of life. Further, y _L is the volume amount of CO + CO ₂ (for example, 1 ml / g) when the life of the insulating paper reaches the end (when the average residual polymerization degree reaches 60%).

For reference, the probability that the life of the transformer will be exhausted after the end of life x _L calculated by the above equation (10) is 84.13% when k = 1 and 97.72 when k = 2. % When k = 3, it is 99.87%. Usually, when predicting the life of a transformer, it is preferable to predict the life of the transformer earlier than it actually is, taking into account the safety factor. This is because if the life of the transformer runs out faster than expected, it will have a serious adverse effect on the system using it (power failure, etc.). In this embodiment, as is clear from the above probability value, the probability that the life of the transformer will expire before the end of the life x _L is extremely small. Therefore, the above-mentioned serious adverse effect does not occur. Next, the data processing device 3 outputs the determination result that the transformer is normal and the prediction result of the time when the life of the transformer is reached to the display device 4 and the printer 5 for display and printing (step S17). ).

Next, with reference to FIG. 5, the operation at the time of failure processing will be described. If it is determined in step S12 that the transformer has a failure, the data processing device 3
Is a gas (CO,
CO ₂ , H ₂ , CH ₄ , C ₂ H ₂ , C ₂ H ₄ , C
₂ H ₆ , C ₃ H ₆ , C ₃ H _8, etc.) is investigated, and the cause of failure of the transformer is analyzed based on the composition ratio (step S18). This is because the type of gas generated varies depending on the cause of the failure of the transformer. Next, the data processing device 3 stochastically predicts the future transition of each gas analyzed and measured in step S2 (step S19), and calculates the threshold arrival time for each gas based on the prediction result. (Step S20). Next, the data processing device 3 outputs the determination result of the failure of the transformer and the prediction result of the life of the transformer due to the failure to the display device 4 and the printer 5 for display and printing. (Step S17).

In the above embodiment, the average residual polymerization degree of the insulating paper and the average residual polymerization rate of the insulating paper in the future are set to predetermined values based on the volume of CO + CO ₂ contained in the insulating oil. Although the time to fall below is calculated, the current average degree of polymerization remaining of the insulating paper and the average degree of polymerization remaining in the future based on other impurity components (for example, furfural) contained in the insulating oil are calculated. You may make it calculate the time when a rate falls below a predetermined value.

[0043]

According to the invention of claim 1, since the deterioration state of the transformer can be measured without collecting the insulating paper,
The measurement work can be performed extremely easily and quickly, and there is no inconvenience such as power failure. Also, only when it is determined that the oil-filled transformer is operating normally, the average residual polymerization degree of the insulating paper in the oil-filled transformer is calculated based on the current measurement result of the dissolved gas amount. As a result, erroneous calculation results will not be output when the transformer fails.

According to the second aspect of the present invention, whether the current measurement result of the dissolved gas amount is within the fluctuation range estimated by the fluctuation range estimating means or is it protruding to the upper side,
Since it is checked whether the oil-filled transformer is protruding to the lower side, more detailed condition diagnosis of the oil-filled transformer can be performed.

According to the invention of claim 4, the life of the transformer can be predicted without collecting the insulating paper. Therefore, the predicting work can be performed very easily and quickly, and the inconvenience such as a power failure does not occur. In addition, as a result of being able to predict the life, the number of inspections of the oil-filled transformer can be greatly reduced, and the inspection cost can be reduced. In addition, only when it is determined that the oil-filled transformer is operating normally, the life of the oil-filled transformer is predicted and calculated based on the current measurement result of the dissolved gas amount. This prevents incorrect calculation results from being output when a device fails.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of an insulation paper deterioration measurement and life prediction system according to an embodiment of the present invention.

FIG. 2 is a graph showing the correlation between the amount of CO + CO ₂ gas generated and the average residual polymerization degree of insulating paper.

FIG. 3 is a graph showing the correlation between the amount of CO + CO ₂ gas generated and the average residual polymerization rate of insulating paper. The graph shown in FIG. 2 was converted into a uniform scale and the oil content actually used was changed. It was obtained by actually measuring a transformer.

FIG. 4 is a flowchart showing the operation of the embodiment shown in FIG.

5 is a flowchart showing the operation of the embodiment shown in FIG.

FIG. 6 is a graph showing a change over time in the amount of CO + CO ₂ gas generated.

[Explanation of symbols]

 11-1n ... Oil-filled transformer 2 ... Gas amount analyzer 3 ... Data processing device 4 ... Display device 5 ... Printer 6 ... Database storage device

Claims (5)

[Claims] 1. A system for diagnosing a deterioration state of an oil-filled transformer based on a time-series measured amount of dissolved gas in insulating oil, wherein the oil-filled transformer is operating normally. Assuming that, the fluctuation range estimation means that stochastically estimates the fluctuation range of the current dissolved gas amount from the past measurement data of the dissolved gas amount, the measurement result of the current dissolved gas amount and the estimated fluctuation. By comparing with the range, the determining means for determining whether or not the oil-filled transformer is operating normally, and the normal operation of the oil-filled transformer by the determining means, the current A deterioration diagnosis system for an oil-filled transformer, comprising an average polymerization degree residual rate calculation means for calculating an average polymerization degree residual rate of insulating paper in the oil-filled transformer based on the measurement result of the dissolved gas amount. 2. The oil-filled transformer is normally operating when the determination result of the current dissolved gas amount is within the fluctuation range estimated by the fluctuation range estimation means. If the current measurement result of the dissolved gas amount is outside the fluctuation range estimated by the fluctuation range estimation means, the oil-filled transformer is out of order or the measurement result has an allowable limit. If it is determined that the above error has occurred, and the current measurement result of the dissolved gas amount is below the fluctuation range estimated by the fluctuation range estimating means, the measurement result has an error exceeding the allowable limit. The insulating paper deterioration diagnosing system according to claim 1, wherein the deterioration diagnosing system judges. 3. The oil according to claim 1, wherein the deterioration state of the oil-filled transformer is diagnosed based on the amounts of CO gas and CO ₂ gas dissolved in the insulating oil. Deterioration diagnosis system for input transformer. 4. A system for predicting the life of an oil-filled transformer based on the amount of dissolved gas in insulating oil measured in time series, wherein the oil-filled transformer is operating normally. A fluctuation range estimation means that stochastically estimates the fluctuation range of the current dissolved gas amount from the past measurement data of the dissolved gas amount, the measurement result of the current dissolved gas amount and the estimated fluctuation range. By comparing with the determining means for determining whether the oil-filled transformer is operating normally, and when the normal operation of the oil-filled transformer is determined by the determining means, the dissolved gas amount The life prediction system for an oil-filled transformer, comprising: a prediction calculation unit that predicts and calculates a time when the amount of dissolved gas reaches a predetermined threshold value as a life expiration time based on the change with time to the present. 5. The oil-filled transformer according to claim 4, wherein the life of the oil-filled transformer is predicted based on the amounts of CO gas and CO ₂ gas dissolved in the insulating oil. Life prediction system.