JP4323396B2 - Power transformer remaining life diagnosis apparatus and remaining life diagnosis method - Google Patents

Description

  The present invention relates to a remaining life diagnosis apparatus for a power transformer and a remaining life diagnosis method.

The life of the transformer depends on the degree of deterioration of the winding insulating paper. Generally, a value at which the “average degree of polymerization” indicating the degree of deterioration decreases to about 450 is defined as the “lifetime standard” (life level). However, it is extremely difficult to collect the winding insulation paper for measuring the average degree of polymerization from the transformer in operation from the viewpoint of maintaining the insulation strength after repairing the insulation paper and the structure of the transformer including the winding.

For this reason, by collecting and measuring chemical components (CO + CO ₂ , furfural, etc.) called degradation indicator products generated in insulating oil as the insulation paper deteriorates, the relationship between the amount produced and the average polymerization degree In general, a method of diagnosing the remaining life indirectly from the accumulated amount is used (for example, Patent Document 1).

However, the constituent materials of transformers that cause the generation of these degradation index products include not only winding insulation paper but also press board and wood, and the generation rate depends on temperature, so the material composition ratio It was difficult to accurately diagnose the remaining life due to variations in the relationship between the amount generated and the average degree of polymerization due to the difference in load, the influence of the load factor, and the outside air temperature. Diagnosis with degradation index products is affected by the difference in thermal history of the highest winding point temperature that each transformer has traversed, so the estimated average degree of polymerization varies greatly and the remaining life diagnosis There was a problem that the error of the result was large.

In addition, as a diagnostic method using thermal history, a method has been proposed in which a time integration curve of average polymerization degree and winding maximum point temperature is created in advance, and the remaining life is diagnosed by comparing the curve with the temperature and time measured by the temperature sensor. (For example, Patent Document 2). In this case, in order to consider the thermal history of the transformer, it is necessary to embed a temperature sensor in the winding and to attach a data processing device such as a measuring device thereof, so that the applicable transformer is limited, When diagnosing one transformer, the equipment is complicated and impractical.
JP 2002-367842 A Japanese Patent Publication No. 2-27809

The present invention improves the above problems, obtains a direct relationship between the thermal history of the winding insulation paper and the average polymerization degree, and eliminates the difference in the thermal history and design conditions that cause error in the diagnosis by the degradation index product. Thus, a remaining life diagnosis device for a power transformer that improves the remaining life diagnosis accuracy is provided.

The remaining life diagnosis apparatus or method for a power transformer according to claims 1 and 3 of the present invention comprises:
(1)
A first means or step for estimating a history of the highest winding point temperature at which the removal transformer has been operated from an outside air temperature record or load history during operation;
(2)
A second means or step for correcting a history of the estimated highest winding point temperature from an insulating oil temperature measured during inspection during operation of the removal transformer;
(3) An index of the life loss V obtained from the history of the corrected winding maximum point temperature of the removed transformer and its duration, and the degree of deterioration of the wound insulating paper measured from the wound insulating paper of the removed transformer. A third means or step for creating a master curve from the relationship with the average degree of polymerization N,
(4)
A fourth means or step for estimating a history of the highest winding point temperature at which the life diagnosis transformer has been operated from an outside air temperature record or load history during operation;
(5)
A fifth means or step for correcting a history of the estimated highest winding point temperature from the insulating oil temperature measured at the time of inspection during operation of the lifespan diagnostic transformer;
(6) Applying the corrected life maximum loss temperature history V ₁ of the life diagnosis transformer and the life loss V ₁ obtained from the duration to the master curve created in the third means or step, sixth average polymerization degree N ₁ estimates the measured remaining life of the lifting transformer from the difference between life loss V ₀ and the lifetime loss V ₁ corresponding to the average degree of polymerization N ₀ lifetime level set It is characterized by comprising the following means or steps.

The remaining life diagnosis apparatus or method for a power transformer according to claims 2 and 4 of the present invention is the average degree of polymerization measured from the winding insulation paper of the removed transformer in the third means or step of creating a master curve. In addition, the average degree of polymerization measured from the accelerated deterioration test of the winding insulating paper is used.

According to the remaining life diagnosis apparatus or method for power transformers according to claims 1 and 3 of the present invention, it is relatively easy to obtain a load diary record of the removed transformer, the nearest weather observation data and the maximum oil temperature. A master curve was created to determine the direct relationship between the life loss V obtained from the thermal history corrected by periodic and inspection inspection records, and the average degree of polymerization N measured from the winding insulation paper of the removed transformer. Life loss V ₁ of the life level set by applying the master curve to the life loss V ₁ obtained from the log of the load of the diagnostic transformer, the nearest weather observation data, the maximum oil temperature and the thermal history corrected by the inspection inspection record by determining the remaining life from the difference between _0, it can be diagnosed accurately remaining service life, high diagnostic accuracy as compared to a diagnostic method using the deterioration index product emissions including many error factors Possible it is.

Therefore, even if the transformer has completely different thermal histories, the master curve (life loss-average polymerization degree curve) serving as an index can be simply expressed by one curve because it follows the Arrhenius rule. Especially in the remaining life diagnosis of power transformers installed outdoors that have large temperature fluctuation factors such as solar radiation and cooling capacity of the cooling device, it is possible to improve the accuracy by correcting from the difference between the measured value and estimated value of the insulation oil temperature .

According to the remaining life diagnosis apparatus or method for a power transformer according to claims 2 and 4, in addition to the average degree of polymerization measured from the winding insulation paper of the removed transformer, further from the accelerated deterioration test of the winding insulation paper By using the measured average degree of polymerization, it is possible to further improve the accuracy of diagnosis particularly at the life level and the dangerous level.

We estimated the degree of deterioration of the winding insulation paper that affects the life of power transformers, and realized a remaining life diagnosis device and remaining life diagnosis method that improved the accuracy of transformer remaining life diagnosis.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. First, in the first means or step, winding insulation paper having the highest winding point temperature (hot spot) is taken for the removed transformer, and the average degree of polymerization is measured. If necessary, the average degree of polymerization may be measured by an accelerated deterioration test of the winding insulating paper.

Next, the winding maximum point temperature is calculated from the past load record (date and time, load factor, etc.) of the removed transformer and the temperature observed at the weather observation point closest to the place where the removed transformer was installed. FIG. 1 is a diagram showing the relationship between the outside air temperature fluctuation and the temperature rise due to the load. The estimated maximum winding temperature θ ₀ during the duration h is the temperature generated by the outside air temperature change θ t and the load current according to the following equation (1). It is estimated by the sum of the rising value of θ _L.
θ ₀ [° C.] = θ t [° C.] + θ _L [K] (1)
θ ₀ : Estimated winding maximum point temperature [° C] for duration h
θt: outside air temperature [° C] for duration h
θ _L : Maximum winding temperature rise [K] for duration h
The specific temperature estimation of the winding maximum point temperature rise value is expressed by the following equation from the relationship between the internal temperature distribution of the transformer at the rated load shown in FIG. 2 and the internal temperature distribution of the transformer during the duration h shown in FIG. .
1. Load factor Lf at duration h
Lf = Px / Pn (= (load data [kW] / power factor) / transformer rated capacity [kVA])
Px: Load at duration h [kW]
Pn: Rated load [kW]
2. Load loss Wcx at duration h
Wcx = (Lf) ² × Wcn
Wcn: Load loss at rated load [kW] (factory test record data quoted)
3. Maximum oil temperature rise value θoil for duration h (see JEC-2200-1995 “Transformer”)
θoil = {(Wcx + Wfn) / (Wcn + Wfn)} ^0.8 × θoiln
Wfn: No-load loss [kW]
θoiln: Maximum oil temperature rise at rated load [K] (factory test record data quoted)
4). Temperature difference between maximum winding point and maximum oil temperature at rated load Δθwmn (see Fig. 2)
△ θwmn = θwn + εmn (= 15 or 10) −θoiln
θwn: Average winding temperature rise at the center at rated load [K]
εmn: Difference between winding maximum point temperature and winding average temperature measured by resistance method (15 ° C for oil natural circulation, 10 ° C for oil forced circulation)
5. Temperature difference between maximum winding point and maximum oil temperature during duration h Δθwm (see JEC-2200-1995 “Transformer” and Fig. 3)
△ θwm = (Lf) ^1.6 × △ θwmn
6). Winding maximum temperature rise value θ _{L for} duration h (see Fig. 3)
θ _L = θoil + △ θwm
7). Estimated maximum oil temperature θoilest for duration h
θoilest = θt + θoil

As a second means or step, the history of the highest winding point temperature estimated by the equation (1) is corrected from the insulating oil temperature measured at the time of inspection during operation of the removal transformer. In other words, since the insulation oil temperature of the transformer is measured during regular inspections and inspections, the highest winding point temperature is corrected by the following equation with reference to the insulation oil temperature periodic record at this time. θ [° C.] = θ ₀ [° C.] + (θoilmeasav [° C.] − θoilestav [° C.]) (2)
θ: Corrected winding maximum point temperature [° C] for duration h
θ ₀ : Estimated winding maximum point temperature [° C] for duration h
θoilmeasav: Actual maximum oil temperature [° C] (Annual average value of maximum oil temperature record measured by regular inspection and monthly inspection)
θoilestav: Estimated maximum oil temperature [° C] (annual average of the estimated maximum oil temperature maximum value obtained by Equation 7)

As a third means or step, a life loss V obtained from the history of the corrected winding maximum point temperature θ _i of the removed transformer and its duration h _{i is} obtained by equation (3).

Next, FIG. 4 shows the relationship between the life loss V and the average polymerization degree N as an index of the degree of deterioration of the winding insulation paper measured from the accelerated insulation test of the winding insulation paper and the winding insulation paper of the removed transformer. Plot as shown. With respect to a plurality of removed transformers, the above-described means is performed, and the relationship between the life loss V and the average polymerization degree is plotted. For example, for the removal transformer A, the life loss V _A = exp (b θ _A ) × h _A , the average polymerization degree N _A , and for the removal transformer B, the life loss V _B = exp (b θ _B ) × h _B , Average polymerization degree N _B , for removal transformer C, life loss V _C = exp (b θ _C ) × h _C , for average polymerization degree N _C , accelerated degradation sample E, life loss V _E = exp (b A master curve shown in FIG. 4 is created by obtaining θ _E ) × h _E , average polymerization degree _{NE, and the} like. From this master curve, for example, when the average degree of polymerization is reduced to 450, this is used as a life loss to determine V ₀ .




For example, when the average degree of polymerization is reduced to 250, the danger level is set.
Here, the temperatures θ _{A to} θ _E and θ ₀ are equivalent temperatures with respect to the total movement time h _{A to} h _R , h ₀ , and the following θ and h are also the same.

As a fourth means or step, from the past load record (date and time, load factor, etc.) that the life span diagnostic transformer has been operated and the temperature observed at the weather observation point closest to the place where it was installed Calculate the highest winding temperature. The highest winding point temperature is calculated by the above equation (1).

As a fifth means or step, the history of the estimated maximum winding point temperature is corrected by the above equation (2) with reference to the periodic record of the insulating oil temperature measured at the time of inspection during the operation of the lifespan diagnostic transformer. .

As a sixth means or step, the life loss V ₁ obtained from the history of the corrected winding maximum point temperature of the lifespan diagnostic transformer and its duration is obtained by the following equation (5).

When the life loss V ₁ of this life diagnosis transformer is applied to the master curve, the average polymerization degree N ₁ is estimated, and the life diagnosis is made from the difference from the life loss V ₀ of the life degree of the average polymerization degree 450 set in the master curve. The remaining life loss V ₂ of the transformer is calculated.
Remaining life loss of life-tested diagnostic transformer V ₂ = V ₀ −V ₁ (6)

Assuming that the lifespan diagnostic transformer will continue to operate in the same operating conditions as now,


Since in expressed, (8) when the right side of the equation (7) as shown in equation becomes equivalent to V _2, a remaining life h _2i.
V ₂ = exp (bθ ₁₁ ) × h ₂₁ + exp (bθ ₁₂ ) × h ₂₂ +... + Exp (bθ _1n ) × h _2n (1 ≦ n ≦ m 2) (8)
Therefore, the remaining life h _2i is
h _2i = h ₂₁ + h ₂₂ + ... + h _2n (9)
Thus, the remaining life is diagnosed as remaining (h ₂₁ + h ₂₂ +... + H _2n ).

The power transformer remaining life diagnosis device of the present invention is programmed and recorded on a recording medium such as a CD ROM, and this is installed in a computer, and data is input to be operated for calculation. Diagnose the remaining life of the transformer.

It is explanatory drawing which shows the relationship between the external temperature fluctuation | variation and the temperature rise by load. It is a conceptual diagram which shows the temperature rise distribution of a transformer winding and oil at the time of a rated load. It is a conceptual diagram which shows the temperature rise distribution of the transformer winding and oil in the continuation time h. It is a graph which shows the master curve showing the relationship between the lifetime loss of insulating paper, and an average degree of polymerization. From the lifting transformer to date lifetime loss V ₁ and lifetime level of life loss V ₀ Metropolitan obtained from the master curve, determine the remaining lifetime loss V ₂ of the lifting transformer, the now remaining life h ₂ It is explanatory drawing which shows the relationship calculated | required. It is a block diagram which shows this invention.

Claims (4)

(1) a first means for estimating a history of the highest winding point temperature at which the removal transformer has been operated from at least an outside air temperature record during operation and a load history;
(2) a second means for correcting the estimated history of the highest winding point temperature based on the insulating oil temperature measured at the time of inspection during operation of the removed transformer;
(3) An index of the life loss V obtained from the history of the corrected winding maximum point temperature of the removed transformer and its duration, and the degree of deterioration of the wound insulating paper measured from the wound insulating paper of the removed transformer. A third means for creating a master curve showing the relationship with the average degree of polymerization N,
(4) a fourth means for estimating a history of the highest winding point temperature at which the life-time diagnostic transformer has been operated from at least an outside air temperature record during operation and a load history;
(5) a fifth means for correcting the estimated history of the highest winding point temperature based on the insulating oil temperature measured at the time of inspection of the lifetime diagnostic transformer;
(6) Apply the life loss V ₁ obtained from the corrected winding maximum point temperature history and its duration to the master curve created by the third means to obtain the current average A sixth means for estimating the degree of polymerization N ₁ and measuring the remaining life of the life-tested diagnostic transformer from the difference between the life loss V ₀ corresponding to the average degree of polymerization N ₀ of the set life level and the life loss V ₁ A remaining life diagnosis device for a power transformer, characterized by comprising:   The remaining life diagnosis device for a power transformer according to claim 1, wherein in the third means for creating the master curve, the life loss and the average polymerization degree obtained from the accelerated deterioration test of the winding insulating paper are used in combination. . (1) a first step of estimating a history of the highest winding point temperature at which the removal transformer has been operated from at least an outside air temperature record during operation and a load history;
(2) a second step of correcting the estimated winding maximum point temperature history based on the insulating oil temperature measured during inspection during operation of the removed transformer;
(3) An index of the life loss V obtained from the history of the corrected winding maximum point temperature of the removed transformer and its duration, and the degree of deterioration of the wound insulating paper measured from the wound insulating paper of the removed transformer. A third step of creating a master curve showing the relationship with the average degree of polymerization N,
(4) a fourth step of estimating a history of the highest winding point temperature at which the life-time diagnostic transformer has been operated from at least an outside air temperature record during operation and a load history;
(5) a fifth step of correcting the estimated winding maximum point temperature history based on the insulating oil temperature measured at the time of inspection of the lifetime diagnostic transformer;
(6) Apply the life loss V ₁ obtained from the corrected winding maximum point temperature history and its duration to the master curve created in the third step, and calculate the current average A sixth step of estimating the degree of polymerization N ₁ and measuring the remaining life of the life-tested diagnostic transformer from the difference between the life loss V ₀ corresponding to the average degree of polymerization N ₀ of the set life level and the life loss V ₁ A remaining life diagnosis method for a power transformer, characterized by comprising:   4. The method for diagnosing the remaining life of a power transformer according to claim 3, wherein in the third step of creating the master curve, the life loss and the average polymerization degree obtained from the accelerated deterioration test of the winding insulating paper are used in combination. .