JP2938298B2 - Method for estimating salt content on outdoor insulators - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining the amount of contamination of an outdoor suspension insulator used to insulate and support a transmission line from the ground.

[0002]

2. Description of the Related Art It is very important to grasp the state of contamination of outdoor insulators in order to eliminate power failures. The amount of contamination of the insulator is evaluated based on the amount of salt attached to the insulator surface. Most of the substances that adhere to the insulator surface are actually salt, but other substances also adhere. The attached salt content is a value obtained by examining the conductivity of the attached matter and converting all the attached matter into an amount equivalent to the salt content from the relationship between the salt content in the saline solution and the conductivity that is known in advance. That is, the amount of attached salt corresponds to the amount corresponding to the electrical conductivity of whatever fouling substance, and indicates the degree of fouling of the insulator.

Conventionally, as a method of determining the amount of salt attached to an insulator, a pilot insulator is installed near a power transmission tower, a pollutant attached to the surface of the insulator is peeled off, and the amount of salt attached is determined from the conductivity. . The amount of the attached salt corresponds to the amount of contamination of the insulator used for the transmission line near the pilot insulator. These pilot insulators are arranged at various points on the transmission line, and the status of contamination of the transmission line insulator is grasped. A device that automatically removes pollutants from a pilot insulator and obtains and outputs the amount of salt attached thereto is also used.

[0004]

However, the conventional apparatus as described above has a problem that the accumulated amount of salt attached to the insulator surface cannot be obtained. That is, in the measurement method using the pilot insulator, the pollutant is peeled off each time the measurement is performed, and thus the measured value is only the accumulated amount of salt deposited from the previous measurement. Insulators used for transmission lines have accumulated accumulated salt content from the past. In fact, when heavy rain falls, considerable deposits run down, but persistently adhered fouling materials are less likely to come off. Therefore, the method using the pilot insulator does not always accurately indicate the amount of salt attached to the actually used insulator.

As a method of determining the amount of contamination of an insulator actually used in a transmission line, a method of determining a leakage current flowing on the surface of each insulator by a current transformer interposed in a ground wire of the insulator has been known. Have also been studied in various ways. However, it was very difficult to estimate the amount of salt attached to the insulator from the leakage current. In other words, the leakage current greatly varies depending on the surrounding weather conditions, particularly when wet and dry, and also varies depending on the applied voltage. Further, when a leakage current flows through the insulator, a drying zone is formed on the surface of the insulator by Joule heat due to the current, and the leakage current fluctuates. Further, an arc discharge occurs between the dry zone and the wet zone, and a pulse-like current is mixed in the leakage current. As described above, the phenomenon at the time of fouling is extremely complicated, and thus cannot always be evaluated simply by the magnitude of the leakage current.

An object of the present invention is to make it possible to estimate the amount of salt attached to a suspension insulator that is actually used from a leakage current.

[0007]

In order to achieve the above object, according to the method of the present invention, when an AC voltage is applied to a suspension insulator that insulates and supports an outdoor power transmission line from the ground, the AC power is applied through the insulator surface. The leakage current flowing to the ground is obtained over a predetermined period, and this leakage current is converted into sampling data that is peak-held at each set time of the applied voltage, and the frequency at which each of the sampling data occurs within the predetermined period is calculated. From the frequency distribution pattern indicating the relationship between the frequency and the size of each sampling data, the amount of salt attached per unit surface area of the suspension insulator is determined.

[0008]

According to the configuration of the present invention, the leakage current flowing through the actually used suspension insulator is determined over a predetermined period. This leakage current is peak-held at each set time of the applied voltage and converted into sampling data. The frequency at which each of the sampling data occurs within a predetermined period is obtained.
The present inventors have found that the frequency distribution indicating the relationship between the frequency and the sampling data has a unique pattern determined by the applied voltage and the amount of attached salt when the surrounding fog condition is a high concentration of 5 to 8 g / m. I discovered that. Therefore, when the high-concentration fog is generated, if the frequency distribution pattern is examined, the amount of salt attached to the insulator surface can be estimated.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the embodiments of the present invention, the results of a soiling test on a suspension insulator will be described. The test is 5-8g
/ M ³ mist is artificially generated. In this mist, two suspension insulators are connected in series, and suspended at both ends while suspended vertically.
Hz AC voltage was applied. Leakage current was measured by interposing a current transformer in series with the suspension insulator. Here, the fog density was measured using a heating type fog density meter described in the cited document (1). The suspension insulator is JIS-
A 250 mm suspension insulator used for most of the outdoor transmission lines described in C-3810 was used, and the amount of attached salt was artificially changed under several conditions.

Reference document (1): Paper No. 299 of the Institute of Electrical Engineers of Japan, Power and Energy Division, 1991. The measured value of the leakage current is every half cycle of the applied voltage (this setting time is arbitrary, (Set for each half-wave and negative half-wave), the maximum value during the half cycle is stored as sampling data, and the sampling data (3 × 10 ⁴ ) is continuously stored for a predetermined period, for example, 300 seconds. Accumulated.

FIG. 2 is a frequency distribution diagram of sampling data when the applied voltage is 10 kV and the amount of attached salt is 0.01 mg / cm ² . That is, the horizontal axis indicates the size of the sampling data, and the vertical axis indicates the frequency of occurrence of the size of the sampling data among all the sampling data. FIG. 2 shows three curves of a solid line, a dotted line, and a dash-dot line.
This is the result of processing the sampling data for 00 seconds.
The form of the frequency distribution is characterized in that the frequency is biased toward the small current side, and the frequency monotonically decreases as the current increases. Here, such a shape is temporarily referred to as a pattern A.

FIGS. 3 to 5 are frequency distribution diagrams of sampling data under conditions different from those in FIG. That is, FIG. 3 shows that the conditions are as follows: applied voltage 18 kV, attached salt content 0.1
For mg / cm ^2, Figure 4 is the applied voltage 12 kV, when the deposition amount of salt 0,05mg / cm ^2, Figure 5 is an applied voltage 12
The case of kV and the attached salt content of 0.1 mg / cm ² are shown, and the horizontal axis and the vertical axis are the same as those in FIG. Also, the solid line,
Each of the three curves of the dotted line and the dashed line is also a result of processing the sampling data for 300 seconds at different points in time, as in FIG.

A characteristic form of the frequency distribution in FIG. 3 is that a curve that monotonously decreases with an increase in current has a bending point on the way, and a large current component is included in the sampling data. Such a shape is temporarily referred to as a pattern B. The characteristic shape of the frequency distribution in FIG.
One peak is formed and the maximum is seen. Such a shape is temporarily referred to as a pattern C.

The characteristic form of the frequency distribution in FIG. 5 is that the curve forms a plurality of peaks, and the pattern D
Provisionally. As a result of performing many tests other than those shown in FIGS. 2 to 5, it was found that the frequency distribution of the sampling data can be roughly classified into four types of patterns A to D. FIG. 6 is a frequency distribution diagram schematically showing various patterns of the frequency distribution of the sampling data. The frequency distribution patterns are A, B, C, and D from the upper stage to the lower stage.

FIG. 1 is a pattern distribution diagram obtained by classifying the above-described test results into patterns and plotting them at positions corresponding to the applied voltage and the amount of attached salt. The amount of attached salt on the vertical axis is on a logarithmic scale. The alphabetic symbols of each pattern were plotted as they were under the corresponding conditions. According to FIG. 1, it can be seen that the types of patterns generated at the boundaries 1 and 2 are roughly separated. That is, the lower left area of the boundary 1 is the pattern A,
The patterns C and D are mixed in the area between. Further, the pattern B occupies most of the upper right area of the boundary line 2. Each pattern may be slightly changed near the boundary lines 1 and 2, but it can be seen that the pattern largely depends on the applied voltage and the amount of attached salt. As both the applied voltage and the amount of attached salt increase, the pattern A →
C, D → B, and the condition is close to the flashover of the insulator.

The phenomenon in which the frequency distribution pattern is divided by the boundaries 1 and 2 as shown in FIG. 1 is a fact first found by the present inventors. If the leakage current of a suspended insulator in actual use is measured during dense fog and the frequency distribution pattern is known, the approximate range of the amount of salt attached to the suspended insulator can be known from the applied voltage at that time and FIG. . FIG. 1 shows a test result in the case of a double suspension insulator. 2
According to the test results of a plurality of suspension insulators, the amount of salt attached to an arbitrary number of suspension insulators can be estimated by converting the applied voltage per suspension insulator. That is, if the numerical value on the horizontal axis in FIG. 1 is halved, it can be converted into a diagram showing the relationship between the voltage applied per insulator and the amount of attached salt.

Although the predetermined period for accumulating the sampling data is 300 seconds (5 minutes) in FIG. 1, it is generally arbitrary. However, based on the fact that it is better to measure during a period in which the fog condition is relatively stable and the required number of sampling data, it is appropriate to set the predetermined period to several minutes to tens of minutes.

[0018]

As described above, according to the present invention, the amount of salt attached to the suspension insulator is estimated from the frequency distribution pattern and the applied voltage of the leakage current sampling data. By this method, the amount of contamination of the actually used insulator can be obtained. Unlike the conventional method, there is no work to remove the contaminants on the surface of the pilot insulator, so it is possible to calculate the accumulated amount of salt attached to the surface, and if the computation processing of the sampling data and the pattern determination of the frequency distribution are performed by a computer. The amount of attached salt can be known instantaneously.

[Brief description of the drawings]

FIG. 1 is a pattern distribution diagram showing a relationship between a frequency distribution pattern, an applied voltage, and an attached salt amount.

FIG. 2 shows an applied voltage of 10 kV and an attached salt content of 0.01 mg /
Frequency distribution diagram for cm ²

FIG. 3 shows an applied voltage of 18 kV and an attached salt content of 0.1 mg / c.
Frequency distribution diagram for m ²

FIG. 4 shows an applied voltage of 12 kV and an attached salt content of 0.05 mg /
Frequency distribution diagram for cm ²

FIG. 5: Applied voltage: 12 kV, amount of attached salt: 0.1 mg / c
Frequency distribution diagram for m ²

FIG. 6 is a frequency distribution diagram schematically showing various patterns.

[Explanation of symbols]

 1 boundary line 2 boundary line

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-48-95590 (JP, A) JP-A-64-31062 (JP, A) JP-A 4-43274 (JP, U) JP-A Sho-56- 1323 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) G01R 31/12-31/20

Claims (1)

(57) [Claims] 1. A method for determining a leakage current flowing to the ground via an insulator surface when an AC voltage is applied to a suspension insulator which insulates and supports an outdoor power transmission line from the ground over a predetermined period of time. Is converted into peak-held sampling data for each set time, and the frequency at which each of the sampling data occurs within the predetermined period is obtained. From the frequency distribution pattern indicating the relationship between this frequency and the size of each sampling data, A method for estimating the amount of salt attached to an outdoor insulator, wherein the amount of salt attached to a suspended insulator per unit surface area is determined.