JP2001231119A - Insulator contamination detector and insulator contamination detecting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulator contamination detector and an insulator contamination detecting system that can always accurately monitor contamination of insulator. SOLUTION: A leak current of an insulator 1 is detected with a current transformer 3 and an output signal is converted to an optical signal with a converting means 5. A DC bias current is supplied to a conversion element to give a low impedance thereto. Consequently, a low price current transformer may be used. Since an optical signal is transferred to a detector main unit 9 with an optical fiber 8, space noise is no longer picked with the signal line. The detector main unit isolates the optical signal to a DC element corresponding to the DC bias current and an AC element corresponding to the leak current to determine contamination degree of insulator based on the ratio of these elements. Since the DC element and AC element are attenuated in the same manner, an accurate leak current can be obtained by taking a ratio of these elements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting contamination of an insulator and a system for detecting contamination of the insulator using the apparatus.

[0002]

2. Description of the Related Art Insulators connected to electric power equipment are deteriorated in insulation performance when the insulators are contaminated by salt or the like. In the initial stage of insulator contamination, a partial discharge occurs in the insulator and an insulator leakage current flows. If this condition is left unattended and the insulator is further contaminated, it may develop into a serious accident such as a ground fault or short circuit accident due to insulation breakdown, which may be a serious problem leading to a trouble in power supply. Therefore, it is necessary to detect the initial state of insulator contamination and perform insulator cleaning to restore the insulating performance of the insulator.

Conventionally, methods for detecting the initial state of insulator contamination include a method using a pilot insulator, a method for detecting an electromagnetic wave accompanying partial discharge, and a method for detecting a leak current of an actual machine. In the method using the pilot insulator, the contamination of the insulator proceeds in the same manner as in the actual machine by placing the pilot insulator in the same environment as the actual machine. When measuring the degree of pollution, a brush-washing method is used to manually collect the surface fouling substance and measure the amount of fouling, or a method of automatically immersing the pilot insulator in fresh water to dissolve the attached salt and automatically measure the salt concentration. It is used.

A method of detecting an electromagnetic wave is to detect the presence or absence of contamination by detecting an electromagnetic wave generated by a partial discharge from an actual device using an antenna sensor and analyzing the intensity and frequency of the detected electromagnetic wave. . In a method of detecting a leakage current of an actual device, a current transformer is inserted in a path of the leakage current, the leakage current is directly measured, and the degree of contamination is determined from the value.

[0005]

Each of the above-mentioned conventional detection methods has the following problems. In the detection method using the pilot insulator, it is necessary to newly provide a steel tower and a foundation on which the pilot insulator is installed. In addition, it is necessary to wash the pilot insulator manually in accordance with the washing of the actual insulator. When this cleaning is performed automatically, it is necessary to provide a device for cleaning the pilot insulator in accordance with the cleaning of the insulator. In this method, the measurement of the amount of fouling is also performed manually, so that a great deal of time and costs are spent on the apparatus and labor.

Further, as a method of installing a pilot insulator, there is a method of automatically cleaning the insulator and measuring the amount of contamination. However, since this method uses a mechanical device, the introduction cost is expensive, and a dedicated cleaning method is used. It is necessary to prepare equipment for producing distilled water for use and a water storage tank. In addition, the periodic maintenance increases the management cost for managing the mechanical device, the distilled water production device, and the water storage tank. For this reason, such a device is introduced only in important substations, and is an obstacle to maintenance labor saving.

[0007] Further, the contamination may vary depending on the installation location or type of the insulator, and in the above-described method, only the contamination tendency of one type of insulator is grasped. Furthermore, in the above method, since the pollutants on the surface of the pilot insulator are irreversibly collected, once the amount of contamination is measured, the surface of the pilot insulator differs from the actual amount of contamination of the insulator. The amount of fouling cannot be measured frequently and continuously.

[0008] For this reason, several pilot insulators are provided and operated separately for measurement of accumulated pollution amount and for occasional measurement, and estimation of the current pollution amount is performed by adding to the previous measurement value. ing. However, in practice, the measured value is often high, despite the fact that the pollutants on the insulator are removed due to the cleaning effect of rainfall during that time, and the actual amount of insulator fouling is low. However, there is a problem that it is not possible to directly grasp the pollution status of insulators of electric power equipment in real time.

Next, in the method of detecting electromagnetic waves, the antenna sensor detects external noises other than those caused by the pollution phenomenon, and the frequency band of the generated electromagnetic waves varies depending on the type of insulator and the state of the pollution. In addition, it is difficult to detect partial discharge due to insulator contamination. In the method of measuring the leakage current of the insulator with a current transformer, if a very large leakage current flows due to the contamination, the contamination can be detected. However, in order to detect the initial contamination, it is necessary to detect a minute leakage current of several tens μA to several mA. In this leakage current region, the influence of environmental factors such as humidity, rainfall, and temperature on the leakage current value is relatively large. Therefore, it has been difficult to determine whether the increase in the leakage current is due to contamination or an environmental factor. In addition, a current transformer for detecting a leakage current has a low detection sensitivity in a very small area, and therefore has several tens μA.
There is a disadvantage that it is not possible to detect a small leakage current of up to several mA.

Further, a phenomenon in which a very small pulse leakage current of several tens μA to several mA is similarly superimposed in the course of the progress of contamination,
Although there is a phenomenon that the waveform is distorted, such a minute waveform distortion and pulse current cannot be detected. Here, the fact that detection using a general current transformer has low detection sensitivity in the minute current region will be described. Leakage current due to insulator fouling is several tens μA to several mA, and current accompanying discharge is several mA to several hundred A. When the current to be detected is small, the exciting impedance of the current transformer becomes smaller in the low current region relative to the current to be measured, so that the surrounding magnetic field links to the current transformer winding. This makes it more susceptible to magnetic noise, and noise larger than the measured current is generated by the magnetic noise. For this reason, the current transformer does not function as a current source having a large internal impedance, which is a major feature of the current transformer, and is susceptible to noise.

In particular, a large induced magnetic field is generated by a current in the vicinity of a device through which a current flows, such as a substation.
The small current could not be detected by the current transformer. On the other hand, there is a device in which a minute current can be detected using a current transformer having a built-in amplifier. In this case, to use a metallic signal line for connecting the current transformer to the detection device main body, the signal line functions as an antenna sensor,
It is superimposed on the spatial noise signal. In particular, electromagnetic radiation from an external corona generated in the charging section of the device may be superimposed on the signal of the current transformer. In this case, the inter-signal noise may cancel the signal, and the discharge current may be reduced.

Further, when a discharge occurs, there is a risk that the detecting device may be damaged by surge energy. As described above, since it is easily affected by the electromagnetic noise in the space, it is necessary to use a very expensive system in consideration of the countermeasure. Furthermore, several tens μA in the process of progress of insulator fouling
In order to detect the minute distortion of the leakage current waveform of about to several mA and the superposition of the pulse current, in addition to the detection of the minute current, the gain bandwidth of the amplifier, that is, the GB product is limited, so that the frequency range from several tens Hz to several MHz is obtained. It was difficult to amplify a small current in a wide band. Further, if the band is widened, the above-described noise is mixed in, and this is inadvertently amplified, so that the SN characteristic is deteriorated. For this reason, it has been general to obtain sensitivity by manufacturing a general small current detecting device with a limited band, such as a device dedicated to 50 Hz.

In the above conventional method for detecting insulator fouling,
The pollution progresses rapidly due to a typhoon or the like, or the pollution recovers due to a cleaning effect by rainfall. However, with the conventional fouling detection method, it is impossible to monitor fouling in real time, it is not possible to perform continuous measurement by collecting irreversible fouling substances, and it is difficult to simultaneously measure insulators of equipment with different specifications. There's a problem. Therefore, it is difficult to grasp the contamination due to the type of the insulator, and it is difficult to determine an accurate cleaning time as a whole.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an insulator fouling detection device capable of accurately monitoring the actual fouling degree of an insulator of an electric device directly and in real time without being affected by noise or an external environment. Things. It is another object of the present invention to provide an insulator fouling detection system that can be applied in a widely distributed manner and that can predict a fouling development area from operation through a network.

[0015]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object. In the present invention,
Instead of the conventional indirect pollution detection method using a pilot insulator, by directly measuring the leakage current of the equipment insulator, the pollution amount of the equipment is grasped directly and continuously. Generally, a phenomenon in which the leakage current increases due to the contamination of the surface of the insulator is observed. However, in order to detect the leakage from the initial stage, it is necessary to detect a very small leakage current without the influence of noise. The leak current method according to the present invention is capable of detecting a very small leakage current of several tens μA to several mA at the initial stage of the contamination, which cannot be measured conventionally, without the influence of noise. Is to be detected.

[0016] For this reason, the danger of flashing of the equipment due to the decrease in the amount of contamination due to rain washing and the increase in the contamination can be directly grasped and monitored in real time in each case, so that compared with the conventional indirect method using the pilot insulator. Detailed application is possible. Further, the detection current transformer for detecting the leakage current of the insulator enables detection of a minute current without being affected by noise. Therefore, a detection current transformer, a current transformer, a conversion element connected to the output side of the current transformer for converting an output signal into an optical signal, and supplying a DC bias current to the conversion element, And means for lowering the impedance of the element.

Then, the optical signal is transmitted to the main body of the detecting device by an optical fiber. The detection device body determines the contamination degree of the insulator based on the transmitted optical signal. Thus, by flowing a DC bias current to the conversion element,
The impedance at the output side of the current transformer can be reduced, and as a result, the magnetic flux density of the current transformer becomes small, so that the excitation impedance of the current transformer becomes relatively large and the minute current of the current transformer becomes small. The region error characteristics are greatly improved. For this reason, the noise resistance characteristic, which is a major feature of the current transformer, is improved, and it becomes possible to measure a minute current such as a leakage current and a partial discharge.

Due to the improvement of the noise resistance of the current transformer in the minute current region and the inherent noise-free performance due to the use of the optical fiber, the detection device main body has a small leakage current and a small noise current without being affected by noise. The detection of the contamination of the insulator can be accurately performed based on the partial discharge current. In addition, the temperature and humidity, which affect the minute leakage current that flows when the surface of the insulator is contaminated, are measured at the same time, and the leakage current value is corrected from these values, so that the influence of these environmental conditions on the leakage current is measured. It is possible to correct and further detect the amount of fouling. In addition, since only the current transformer and the light conversion unit are provided in the electric device, a new dedicated foundation, a tower for installation, or a distilled water production device, such as a method using a conventional pilot insulator, There is no need to prepare a water tank.

For this reason, the cost of introduction and operation is extremely low, and it is possible to introduce it in various places where it could not be introduced before. Therefore, a system for predicting the progress of pollution over a wide range through a network has been developed. It can be built at low cost.

[0020]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an overall circuit configuration of an insulator fouling detection device to which the present invention is applied, FIG. 2 shows a circuit configuration of a detection current transformer in the insulator fouling detection device, and FIG. 1 shows a circuit configuration of a detection device main body.

In FIG. 1, 1 is an insulator attached to a power device (not shown), 2 is a ground wire connecting between a mounting portion of the insulator 1 and the ground, and 3 is a leak flowing through the ground wire 2. A current transformer for measuring current / discharge current, which constitutes a part of the detection current transformer 4. The detection current transformer 4 includes the current transformer 3 and the measurement circuit 5. FIG. 2 shows a configuration of the detection current transformer 4.

Referring to FIG. 2, the current transformer 3 includes a core 6 and a winding 7, and the ground wire 2 passes through the center of the core 6. The electric signal detected by the winding 7 is guided to the measuring circuit 5. This electric signal is applied to the light emitting diode LED via the capacitor C and the diode D1. This capacitor C
Is provided so that a DC bias current does not flow through the winding 7, and has a value that minimizes the impedance with respect to the commercial frequency component detected by the current transformer 3. The diode D1 is provided for protecting the light emitting diode LED.

A light emitting diode LED is supplied from a DC power supply DS through resistors R1 and R2 and a Zener diode ZD2.
Passing a DC bias current I ₁ to. Thereby, the impedance of the light emitting diode LED decreases. Further, the DC power source DS supplies a resistor R to the diode D1.
1, R3, the DC bias current I ₂ flows through the Zener diode ZD1. Thereby, the diode D1
Is reduced in impedance.

Therefore, the output impedance seen from the winding 7 is low, and a minute current such as a leakage current can easily flow through the light emitting diode LED. The light emitting diode LED outputs light corresponding to the current flowing therethrough. The optical signal is a combination of the leakage current and the direct current component of the AC component and the DC bias current I ₁ of the discharge current.

Here, Zener diodes ZD1, ZD
2 will be described. The DC bias current I ₁ is
As will be described later, it is necessary to use a constant current because it becomes a reference for the final calculation. However, since the forward voltage of the light emitting diode LED and the diode D1 changes according to the temperature change, in order to prevent the current value from fluctuating with the temperature change, the light emitting diode LED and the diode D1 have the same reverse direction as the light emitting diode LED and the diode D1. Zener diode Z with temperature coefficient
D1 and ZD2 are inserted to perform temperature compensation. Thus, the DC bias currents I ₁ and I ₂ are always constant.

Returning to FIG. 1, an optical signal output from the light emitting diode LED is transmitted to the main body 9 of the detecting device by the optical fiber 8. Unlike the metallic signal line, the optical fiber 8 does not pick up spatial noise, so that no noise is superimposed on the transmitted optical signal. Further, a temperature sensor and a humidity sensor 21 are provided, and their detection outputs are input to the detection device main body 9.

FIG. 3 shows a circuit configuration of the detection device main body 9, and FIG. 4 shows signal waveforms at key points of the circuit of FIG. The optical signal transmitted by the optical fiber 8 is converted into an optical / electrical
Is converted into an electric signal. This electric signal waveform includes a DC component and an AC component as shown in FIG. DC component corresponds to the DC bias current I ₁ of FIG. 2, the AC component current transformer 3 in Fig. 2 correspond to the signal detection. This electric signal is amplified by the preamplifier 12, and
An AC / DC separation circuit 13 separates the AC component AC and the DC component DC. FIG. 4B shows the separated AC component AC, and FIG. 4C shows the DC component DC.

The AC component AC is input to a peak hold circuit 16 through an amplifier 14 and a full-wave rectifier 15.
The peak hold circuit 16 detects a peak value P / H of an AC component, and the peak value P / H is converted into a digital signal by an AD converter 17. The AC component AC is further input to an effective value conversion circuit 19 through an amplifier 18. The effective value conversion circuit 19 obtains an effective value RMS from the AC component, and the effective value RMS is converted into a digital signal by the AD converter 17.

The signal value of the DC component DC is calculated by the A / D converter 1
7 is converted into a digital signal. In addition, the temperature,
The temperature and humidity detected by the humidity sensor 21 are the signal converter 2
The signal is converted into an analog signal by the A / D converter 2, and is converted into a digital signal by the A / D converter 17.

The output signal of the A / D converter 17 is
Is output to The bus 23 includes a CPU 24 and a memory 2
5. The input / output interface 26 is connected. The input / output interface 26 includes a display 27, a printer 2
8. The operation panel 29 and the relay 30 are connected. next,
The operation of the insulator fouling detection device will be described.

FIG. 5 is a waveform diagram for explaining the operation principle of the insulator contamination detecting device. When the insulator 1 is not contaminated, the peak value of the leakage current does not change when the insulator surface is dried or when moisture is attached. The leakage current becomes a capacitive current due to the relationship between the capacitance of the insulator 1 (several pF for the 77 kV insulator) and the normal ground voltage, and has a waveform as shown in FIG. This is basically a sine wave. The peak value is about several tens μA.

If salt adheres to the insulator 1 due to sea breeze or the like and becomes soiled, the resistance value of the insulator 1 extremely decreases. In this case, the leakage current is obtained by adding a resistive current to a capacitive current. Furthermore, since the moisture adheres to the surface of the insulator 1 in a mottled manner, the capacitive current also increases. Therefore, as the contamination progresses, the current waveform becomes close to a triangular wave as shown in FIG. 5B, the peak value also increases, and rises to about several hundred μA.

When the contamination further progresses, the current waveform becomes
As shown in FIG. 5C, a waveform including a whisker-like pulse due to a local arc is observed. The peak value also increases, and the peak value becomes several mA to several tens mA. Further, this waveform changes depending on temperature, humidity, and the like. Based on the above operation principle, the CPU 24 determines the degree of contamination of the insulator 1 by the following method.

FIG. 6 is a block diagram showing the function of the determination operation of the CPU 24. The first calculating means 31 includes:
The peak value P / H of the AC component of the detection signal and the DC component DC are input, and the ratio between the two is calculated. Calculated peak value P / H
The ratio between the DC component and the DC component is compared in the determination unit 32 with the pollution degree management value stored in the management value storage unit 33. The peak value P / H is, as shown in FIG.
(B) Light pollution (initial stage) and (c) heavy pollution (local arc generation) are different. By preparing control values according to these situations, the pollution degree of the insulator 1 can be determined. Is done.

The effective value RMS of the AC component of the detection signal and the DC component DC are input to the second calculating means 34, and the ratio between the two is calculated. Calculated effective value RMS and DC component DC
Is determined by the first calculation means 3 in the determination unit 32.
The determination is made in the same manner as in the output of FIG. The determination method using the first and second calculation means 31, 34 eliminates the influence of signal attenuation by taking the ratio with the DC component DC. The AC component DC and the DC component DC are similarly attenuated during transmission from the detection current transformer 4 to the detection device main body 9. On the other hand, when the ratio with the DC component DC is taken, the influence of the signal attenuation can be eliminated to accurately obtain the measured values of the leakage current and the discharge current.

The first and second calculating means 31, 31
In the case of the determination method using No. 34, the dangerous leakage current value differs depending on the type of the insulator 1 and the like. In other words, for the same insulator, the peak value and the effective value increase with the progress of contamination, but if the type of insulator is different, the dangerous leakage current value will be different.
It is necessary to prepare for each specification of each insulator.

Since the peak value P / H and the effective value RMS change substantially in accordance with the degree of contamination of the insulator, one of the first calculating means 31 and the second calculating means 34 is omitted. It is also possible to detect insulator fouling. The peak value P / H and the effective value RMS of the AC component of the detection signal are input to the third calculating means 35, and a crest factor, which is a ratio between the two, is calculated. This crest factor value is determined by the determination unit 3
In 2, the value is compared with the second pollution degree management value stored in the management value storage unit 33. As shown in FIG. 5, the crest factor has different values for (a) non-fouling, (b) lightly fouling, and (c) heavy fouling.

In the case of the non-fouling state shown in FIG. 5A, the waveform of the detected current is substantially a sine wave, and the crest factor (P / H ÷)
RMS / DC) is 1.414. At the time of light contamination shown in FIG. 5B, the detected current waveform is substantially a triangular wave, and the crest factor is 1.732. Fig. 5
In the case of (c) heavy contamination, a waveform including a whisker-like pulse current due to a local arc is generated, the distortion is increased, and a value of crest factor = 2.0 or more is exhibited. Therefore, by preparing a plurality of management values corresponding to these values, the contamination degree of the insulator 1 is determined.

This crest factor changes when pulse current due to external noise is superimposed. However, according to this example, the minute detection current is converted into an optical signal in a wide band, and transmitted without noise, so that only the pulse current and the waveform distortion due to the insulator fouling development phenomenon are utilized using the crest factor. It can be detected easily and accurately.

This change in the crest factor shows the same tendency in any insulator regardless of the kind of the insulator. Therefore, the method of calculating the crest factor can reduce the number of management values to be stored in the storage unit 33, as compared with the method using the first and second calculation units 31, 34. . The determination unit 32 outputs the degree of contamination obtained as a result of the determination, and the degree of contamination is output to the display 27, the printer 28, and the like. When it is determined that the insulator contamination degree has exceeded a predetermined management value, the relay 30 is operated to notify that the insulator cleaning time has come.

The determining unit 32 uses various management values for determining the degree of contamination. The management value storage unit 33 can store a management value according to the specifications of each insulator according to the type of the insulator. In other words, factors that determine the ease of leakage current flow due to contamination, such as the effective length of the insulator, the average diameter, the number of bulks, the size of the bulk, the presence or absence of under-folds, and the depth of under-folds There is. Before the operation of the fouling detection device is started, a management value corresponding to the specifications of the insulator to be monitored is selected from the management value storage unit 33. As a result, there is no need to perform the operation of determining the leakage current by actually polluting the insulator and determining the management value from the contamination level and the value of the leakage current.

The judging section 32 includes the first calculating means 31 and the second
By using both of the above calculation means, it is possible to detect the flashing risk of the insulator, which is the final stage of the development of fouling.
Immediately before the insulator finally flashes due to fouling, a large pulse-like arc current that flows intermittently and short-circuits between the dry belts formed on the surface of the insulator is observed. At this time, since the leakage current waveform is distorted by the large arc current, when simultaneously detecting the specific increase in the crest factor and the specific increase in the effective value of the leakage current, the insulator 1 to be monitored may be in danger of flashover. It is determined that there is.

Thus, it is possible not only to detect the contamination of the insulator but also to directly detect the risk of flashover. In such a case, instead of taking measures to induce a flash accident such as washing insulators in the live state, take appropriate measures such as stopping the line at the opportunity and washing the insulators. . FIG. 7 shows an example in which contamination detection of a plurality of insulators is performed by one device.

When there are a plurality of insulators to be monitored, the contamination does not always proceed to the same degree depending on the place where the insulators are installed and the type of the insulators. Therefore, in order to detect the contamination of all the insulators, in the above-mentioned insulator contamination detection device, a plurality of identical devices are provided for each insulator. However, this results in an expensive device. In this example,
It is possible to simultaneously detect contamination of a plurality of insulators without increasing the cost of the device.

A current transformer 3 is arranged on each ground line 2 of the plurality of insulators 1. The secondary side of each current transformer 3 is a channel selector 3
6 is connected to the measurement circuit 5. Under the control of the controller 37, the channel selector 36 sequentially switches the output of each current transformer 3 in a time-division manner and outputs the output to the measuring circuit 5.
The detection device main body 9 outputs a switching control signal to the controller 37 through the optical fiber 38, and detects contamination of each insulator 1 in a time sharing manner. The configuration of the measurement circuit 5 and the determination unit 32, the method of determining the degree of contamination in the determination unit 32, and the like are described in
As described with reference to FIGS.

With reference to FIG. 8, a description will be given of the correction of the fluctuation of the leakage current due to the humidity. Leakage current due to insulator contamination is
Varies depending on the outdoor environment. The determination unit 32 determines whether the sensor 21
The leak current value is corrected based on the humidity measured by the method, and only the fluctuation of the leak current due to the contamination is accurately grasped. As shown in FIG. 8, when the contamination levels are the same, the leakage current value increases due to an increase in the relative humidity. When the relative humidity is the same, the leakage current value increases due to the increase in the contamination level. In this example, in order to detect only a change in the contamination level, a leakage current value serving as an index for determining contamination is converted into a leakage current value at a relative humidity of 80%, for example. When the measurement result of the humidity and the leakage current value is point A shown in the drawing, this is converted to a leakage current value _AD point at a relative humidity of 80%.

[0047] As a simple correction method, the range of relative humidity shown _{HM L (70%) ~HM H} (95%), since a substantially proportional relationship between the humidity and the leakage current, it is a primary correction. If the current humidity is HMx (%) and the leakage current is ix (mA), the corrected leakage current i converted when the humidity is 80 (%) is
i = ix (80 / HMx).

Referring to FIG. 9, a description will be given of the correction of the fluctuation of the leakage current due to the change rate of the humidity. (A) shows a change in humidity and a change in leakage current over time.
(A) The left side shows a state in which the humidity suddenly changes, and the right side shows a state in which the humidity changes slowly. If the humidity increases rapidly, the leakage current also tends to increase significantly. On the other hand, when the humidity rises slowly, the leakage current does not rise so much. This tendency tends to change as the insulator contamination degree increases.

(B) shows the relationship between the rate of change of humidity, the rate of change of leakage current, and the degree of contamination. As shown in (b), the greater the degree of contamination, the greater the rate of change in leakage current relative to the rate of change in humidity. The determination unit 32 calculates the change rate (% / H) of the humidity per unit time measured by the sensor 21 and the corresponding change rate (mA / H) of the leakage current value per unit time.
The contamination degree of the insulator 1 is determined using the relationship (b). This alone makes it possible to roughly detect the degree of contamination.

Referring to FIG. 10, the correction when the measured humidity is equal to or lower than the lower limit or equal to or higher than the upper limit will be described. As shown in FIG. 8 described above, when the measured humidity falls in a low humidity range, for example, 70% or less, or when the measured humidity is in a high humidity range, for example, 9%.
When it becomes 5% or more, the change of the leakage current becomes unstable. If this is corrected to the value at the time of 80%, the leakage current value after correction becomes rather inaccurate.

When the humidity changes as shown in FIG. 10A, the leakage current changes according to the humidity as shown in FIG. The leakage current value corrected by the humidity in the method shown in FIG. 8 described above eliminates the influence of the humidity change as shown in FIG. However, if the leakage current is similarly corrected when the humidity becomes equal to or less than the lower limit or equal to or more than the upper limit, an incorrect value is obtained as shown in (c).

On the other hand, the judgment unit 32 determines that
If the value is lower or higher than the upper limit, the value immediately before the corrected leakage current value
A₁, A_TwoIs stored. And the humidity is below the lower limit
Or, as long as the value is equal to or more than the upper limit, as shown by a dotted line in FIG.
And the stored corrected leakage current value A ₁, A_TwoUsing insulator
Determine the degree of contamination. When this example is adopted, the humidity is
When it is less than or equal to or greater than the upper limit, a fixed correction leakage current
Value A₁, A_TwoUse During this time, insulator fouling progresses
This is not without the possibility. However, low humidity
If there is no damp wind from the sea,
It can be assumed that there is no loss development. Thus, low
In the case of humidity, the fouling situation does not change.
More accurate judgment by using the previous corrected leakage current value
can do.

The case where the humidity is extremely high is the case of dense fog, relatively strong rainfall, or the like. In such a case, the leakage current value fluctuates frequently and is not stable. Therefore, in a high-humidity situation, performing the humidity correction not only causes an error but also has no meaning in the correction, so that the use of the immediately preceding corrected leakage current value makes a stable determination. In addition,
The predetermined effect can be obtained by storing the immediately preceding corrected leakage current value A ₁ or A ₂ only when the determination unit 32 detects either the lower limit value or less of the humidity or the upper limit value or more. be able to.

Referring to FIG. 11, a description will be given of an example in which the variation of the leakage current due to the temperature is corrected to a temperature of 20 (° C.). The conductivity of the aqueous salt solution changes with temperature. FIG.
As shown in FIG. 1, the leakage current varies with the coefficient k depending on the temperature. Therefore, in the determination unit 32, the sensor 21
From the temperature T ₀ and the leakage current i ₀ coefficient k measured by
The corrected leakage current i ₂₀ is calculated as i ₂₀ = (1+ (20−T ₀ ) ×
k) × i ₀ is corrected.

Thus, it is possible to compensate for a change in leakage current due to a change in temperature, and to make an accurate determination. FIG.
The correction of the fluctuation of the leakage current due to the temperature change rate will be described using FIG. Rapid changes in temperature can result in rapid drying or condensation. When the temperature sudden change occurs, if the correction based on the temperature described with reference to FIG. 11 is performed, an error due to the correction occurs. FIG. 12A shows a change state of a temperature change rate (temperature change per unit time), and FIG.
5 shows a state of change in a corrected leakage current value.

When the temperature change rate exceeds the upper limit value or the lower limit value,
If rapid drying or rapid condensation occurs, an error occurs in the corrected leakage current value, and it becomes impossible to accurately determine the degree of contamination. For this reason, when the temperature change rate exceeds the upper limit value or the lower limit value, the previous values A ₃ and A ₄ are stored as the corrected leakage current values, and are stored while the temperature exceeds the upper limit value or the lower limit value. The degree of contamination is determined using the corrected leakage current values A ₃ and A ₄ .
This makes it possible to determine the degree of contamination while eliminating the effects of rapid drying and rapid condensation. Only when the determination unit 32 detects one of the lower limit value or the upper limit value or more of the temperature change rate, the immediately preceding corrected leakage current value A
₃ or may be configured to store the A _4.

Referring to FIG. 13, the leakage of the insulator surface during freezing is shown.
The correction of the current will be described. It is explained using FIG.
As described, the leakage current value is 20 ° depending on the measured temperature.
Converted into C and corrected leakage current value i₂₀Is used as an index for determining the degree of contamination.
I am. In this case, as shown in FIG.
When it drops to around 0 degree (5 ° to -5 ° C), the leakage current value
Becomes very small, and when converted to 20 ° C,
Positive leakage current value i ₂₀Can not be obtained.

On the other hand, when the temperature measured by the sensor 21 becomes equal to or lower than the predetermined value x ° C. near 0 ° C., a correction value i _{20 obtained} by converting the immediately preceding leakage current value ix into 20 ° C. is stored. Keep it. While the temperature is equal to or lower than x ° C., the degree of insulator contamination is determined using the corrected leakage current value i ₂₀ . The example in which the humidity sensor and the temperature sensor are used as the sensor 21 has been described. According to the present invention, it is possible to use the wind speed sensor, the wind direction sensor, the rainfall sensor, and the like as the sensor 21 to make the determination of the insulator contamination degree more precise.

For example, when the leakage current increases rapidly even when the wind from the sea is not blowing, it is determined that the leakage current is not caused by the progress of the contamination but is caused by, for example, an increase in humidity due to rainfall or the like. If the wind speed exceeds the specified value and the wind direction is from the sea, and if the leakage current rises sharply, it is determined that the contamination has rapidly progressed due to the wind containing salt. At this time, the indicator 2 indicates whether urgent insulator cleaning is necessary.
7 is displayed to inform that the time for cleaning the insulator has come by operating the relay 30.

Although this can be determined only by the humidity sensor, the reliability can be further secured by using the plurality of sensors in combination. A system in which the insulator fouling detection device is arranged in a wide area will be described with reference to FIG. A plurality of devices 39 for detecting insulator fouling by the leakage current described above are arranged in a wide area. These devices 39 are connected to a network 41
To the central monitoring station 42. Each device 39 periodically transmits the detected degree of contamination to the central monitoring station 42. The central monitoring station 42 is provided with means for collectively displaying the status of insulator contamination in various places, and visual display means distributed on a map based on the information.

As a result, the central monitoring station 42 can grasp the progress of the insulator contamination in each place and the extent of the contamination in a two-dimensional manner, and predict in advance the power supply disturbance due to the insulator contamination, that is, the occurrence of salt damage to the electronic equipment. And can be applied to maintenance.

[0062]

According to the present invention, there is provided an insulator fouling detection apparatus capable of accurately monitoring the actual fouling degree of an insulator of an electric device directly and in real time without being affected by noise or an external environment. Can be. Further, according to the present invention, it is possible to provide an insulator fouling detection system which can be widely distributed and applied, and which can be used for operation to predict a fouling development area from a network.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an insulator fouling detection device to which the present invention is applied.

FIG. 2 is a diagram showing a circuit configuration of the detection current transformer of FIG.

FIG. 3 is a diagram showing a circuit configuration of a detection device main body of FIG. 1;

FIG. 4 is a view showing signal waveforms of respective portions in the circuit of FIG. 3;

FIG. 5 is a waveform chart for explaining the operation principle of the insulator fouling detection device of FIG. 1;

FIG. 6 is a functional block diagram of the CPU in FIG. 3;

FIG. 7 is an overall configuration diagram of an insulator fouling detection device according to a second example to which the present invention is applied.

FIG. 8 is a view for explaining correction of leakage current due to humidity in the device of the present invention.

FIG. 9 is a view for explaining correction of leakage current based on the rate of change of humidity in the apparatus of the present invention.

FIG. 10 is a diagram illustrating correction of leakage current when the humidity in FIG. 8 is equal to or lower than a lower limit and equal to or higher than an upper limit.

FIG. 11 is a view for explaining correction of leakage current based on temperature in the device of the present invention.

FIG. 12 is a view for explaining correction of leakage current based on the rate of change of temperature in the device of the present invention.

FIG. 13 is a view for explaining correction of leakage current at the time of icing on the insulator surface in the device of the present invention.

FIG. 14 is a diagram showing a configuration of an insulator fouling detection system of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulator 2 ... Grounding wire 3 ... Current transformer 4 ... Detection current transformer 5 ... Measurement circuit 6 ... Core 7 ... Winding 8 ... Optical fiber 9 ... Detector main body 11 ... Optical / electrical converter 12 ... Preamplifier 13 ... AC / DC separation circuit 14 ... Amplifier 15 ... Full-wave rectifier 16 ... Peak hold circuit 17 ... A / D converter 18 ... Amplifier 19 ... Effective value conversion circuit 21 ... Sensor 22 ... Signal converter 23 ... Bus 24 ... CPU 25 ... Memory 26 input / output interface 27 display unit 28 printer 29 operation panel 30 relay 31 first calculation means 32 determination unit 33 management value storage unit 34 second calculation means 35 third calculation means 36 channel selector 37 controller 38 optical fiber 39 insulator fouling detector 41 network 42 central monitoring station

Continued on the front page (72) Inventor Jin Hoshino 3-7-1, Ichibancho, Aoba-ku, Sendai, Miyagi Prefecture Inside Tohoku Electric Power Co., Inc. Shin Electric Co., Ltd. (72) Inventor Munetaka Saito 1219-6, Ikuhara, Minato-cho, Gunma-gun, Gunma Prefecture Reference) 2G014 AA16 AB62 AC15 2G036 AA21 BB22 CA06 CA08 2G060 AA08 AA20 AE07 EA06 HC02 HC04 HC07 HC10 HC13 HD02

Claims (15)

[Claims] 1. A current transformer for detecting a leakage current of an insulator, a conversion element connected to an output side of the current transformer for converting an output signal into an optical signal, and a DC bias current supplied to the conversion element. A current transformer having means for lowering the impedance of the conversion element; a detection device main body for detecting presence / absence of contamination of the insulator based on the optical signal; and detecting the optical signal from the detection current transformer. An optical fiber for transmitting to an apparatus main body, wherein the detector main body is configured such that, from the transmitted optical signal, a DC component corresponding to the DC bias current and an AC component corresponding to the leakage current. Means for calculating a ratio between the DC component and the AC component; a means for storing a pollution degree management value corresponding to the pollution degree of the insulator; and a leakage current value of the insulator based on the ratio. Calculation Means for determining the degree of contamination of the insulator by comparing with the contamination degree management value. 2. A plurality of current transformers are provided corresponding to a plurality of insulators, and a channel selector for switching a secondary current signal of each current transformer in a time-division manner and outputting the signal to the conversion element. 2. The insulator fouling detection device according to 1. 3. The detecting device body includes: means for calculating a peak value and an effective value of the AC component; means for calculating a ratio between the peak value and the effective value; and a crest factor management value corresponding to a degree of contamination of the insulator. 3. The insulator fouling detection device according to claim 1, further comprising: a unit configured to store the crest factor management value by comparing the ratio with the crest factor management value. 4. 4. The ratio between the peak value and the effective value increases beyond a predetermined second crest factor management value, and the leakage current value exceeds a predetermined second contamination degree management value. 4. The insulator fouling detection device according to claim 3, wherein in this case, it is determined that the danger of the insulator flash has increased, and a warning is issued. 5. A humidity sensor for measuring humidity in the vicinity of the insulator, wherein the detecting device main body corrects the leakage current value to a leakage current value at a standard humidity based on the measured humidity. The current value is used as an index for determining the degree of contamination of the insulator.
The insulator fouling detection device according to any one of the above. 6. A humidity sensor for measuring humidity in the vicinity of the insulator, and means for storing a correspondence relationship between a humidity change rate, a leak current change rate, and an insulator contamination degree, wherein the detection device main body includes The rate of change per unit time is calculated, the rate of change of the leakage current per unit time is calculated, and the degree of contamination of the insulator is determined from the correspondence.
The insulator fouling detection device according to any one of the above. 7. When the current humidity is equal to or lower than a predetermined lower limit management humidity value, the detection device main body determines a correction leakage current value immediately before decreasing the lower limit management humidity value as an index for determining the amount of insulator fouling. The insulator fouling detection device according to claim 5, wherein 8. When the current humidity is equal to or higher than a predetermined upper limit management humidity value, the detection device main body uses the corrected leakage current value immediately before exceeding the upper limit management humidity value as an index for determining the amount of insulator fouling. The insulator fouling detection device according to claim 5. 9. A temperature sensor for measuring a temperature in the vicinity of the insulator, wherein the detecting device main body corrects the leakage current value to a leakage current value at a standard temperature based on the measured temperature. The current value is used as an index for determining the amount of insulator fouling.
The insulator fouling detection device according to any one of the above. 10. A temperature sensor for measuring a temperature in the vicinity of the insulator, wherein the detecting device body calculates a rate of change of the temperature per unit time, and sets an upper limit management value and a lower limit management value for the temperature change rate. Each is set, When the temperature change rate deviates from the upper limit control value and the lower limit control value, the leakage current value at the temperature change rate immediately before the departure is used as an index of the insulator contamination amount determination. 2. The insulator fouling detection device according to claim 1. 11. A temperature sensor for measuring a temperature in the vicinity of the insulator, wherein the main body of the detecting device detects a temperature immediately before the present temperature when the current temperature drops below a preset icing management value near 0 degrees. The insulator fouling detection device according to any one of claims 1 to 8, wherein the corrected leakage current value in (1) is used as an index for determining the amount of fouling of the insulator. 12. The insulator fouling detection device according to claim 1, wherein said means for storing the control value stores a control value corresponding to various insulator specifications as the various control values. apparatus. 13. A sensor for measuring at least one of a wind speed, a wind direction, and rainfall near the insulator, wherein the main body of the detecting device determines the amount of insulator contamination based on environmental conditions detected by the sensor. Item 13. The insulator fouling detection device according to any one of Items 1 to 12. 14. A sensor for measuring a wind speed and a wind direction in the vicinity of the insulator, wherein the detection device main body has a wind direction in a predetermined wind direction range and the wind speed is equal to or higher than a predetermined wind speed. 13. The insulator fouling detection device according to any one of claims 1 to 12, wherein it is determined that rapid fouling is provided when the leakage current value increases, and a warning is issued. 15. An insulator contamination detecting device according to any one of claims 1 to 14, which is dispersedly arranged at a plurality of locations in a wide range, and each device is connected by a network, and a value serving as an insulator contamination index in each of said locations. Is a collective display, and a visual display is provided on which a value serving as an index of the insulator contamination of each region is distributed on a map.