JP2555395B2 - Partial discharge diagnostic device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for diagnosing partial discharge inside an AC power equipment and notifying an abnormality, and particularly to gas insulation housed in a container having an independent structure for each phase. The present invention relates to a partial discharge diagnostic device that is optimal for detecting partial discharge inside a switchgear or the like.

[Conventional technology]

For example, there are various methods for diagnosing an abnormality inside an AC power equipment existing in a substation or a power plant. There is a method in which a partial discharge detection sensor is attached to the ground wire of the power device to detect the amount of discharge, utilizing the fact that a partial discharge occurs inside the power device due to an abnormality. There is also a method of detecting the vibration of the electric power equipment container by a vibration detection sensor (sound sensor) by utilizing the generation of an abnormal sound due to the abnormality.

However, among the methods for detecting internal discharge of, for example, gas-insulated switchgear (hereinafter referred to as GIS) housed in a container with an independent structure for each phase, the ground wire current ( It is difficult to determine external noise by an external diagnostic method that determines by detecting (e.g., due to electric discharge) or container wall vibration.

In other words, the method of detecting the amount of discharge by the ground wire has external noise such as corona in the air, and especially in high humidity such as when it is raining, the corona in the air is liable to occur, making it difficult to judge. Then, the diagnostic function is stopped. Also, in the method of detecting the vibration of the container wall, raindrops in the case of rainy weather become external noise.

Therefore, a method has been proposed, for example, as described in JP-A-55-37868, which uses a combination of a plurality of different types of sensors.

That is, it is a diagnostic method for detecting container wall vibration, in order to eliminate the sound of raindrops hitting the container as external noise,
It is equipped with different types of sensors: vibration detection sensor and discharge detection sensor.

[Problems to be Solved by the Invention]

In the prior art, for example, the external noise of the aerial corona flows through the grounding wire of the device in the case of rain, and no consideration is given to the case where sound noise when raindrops strike the container wall is generated at the same time, In order to prevent malfunction, the diagnostic function must be stopped, and there are problems in terms of device reliability and cost associated with the increase in the number of sensors. These problems are desired to be solved in order to configure an automatic diagnostic device that detects abnormal signs of the diagnosis target device at a minor stage.

An object of the present invention is to provide a diagnostic device that does not malfunction with a small number of sensors.

[Means for solving the problem]

The present invention has been made in a partial discharge diagnostic apparatus for detecting an partial discharge inside an electric power device which is an AC power device and is housed in an independent container for each phase to diagnose an abnormality.

The partial discharge detection sensor attached to the ground wire provided for each phase container, and the amount obtained by multiplying the discharge amount detected from one phase by a coefficient α (0 <α <1.0) and other Means for comparing the amount of discharge detected from the phase, the output means to generate an abnormality to determine that the internal partial discharge is true only when the amount of discharge of the other phase is small, a humidity detection sensor, Coefficient determining means for determining the coefficient α determined as a function of humidity according to the humidity at the time of determination by the detection signal from the humidity detecting sensor.

[Action]

Since the present invention detects the amount of discharge by the partial discharge detection sensor attached to the ground wire, there is no problem of picking up sound noise of raindrops as in the case of detecting container wall vibration. In addition, when discharge is generated by external noise such as corona in the air, similar discharge should be generated in other layers as well. Therefore, by comparing with the discharge amount of other phases, it may be due to external noise. You can judge whether. The coefficient α used in this determination is determined according to the humidity, which is greatly related to the susceptibility to the occurrence of external noise, so that the above determination can be performed more accurately.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1
Is a power device housed in an independent container for each phase,
It is an electric device for diagnosing the presence or absence of abnormality with the device of the present invention.
For example, there is GIS. 2 is a grounding point provided for each container of each device, and a high-frequency CT as a partial discharge detection sensor
3 is installed. The output signals of multiple high frequency CT3 are
It is input to a plurality of channels of the diagnostic device 20 by the coaxial cable 4 or the like. Input to each channel. The signal input to each channel is amplified by the amplifier 5 and then the filter 6 selects only the signal having the predetermined frequency component. The peak hold circuit 7 holds the maximum amplitude of the signal. The maximum amplitude of the signal is sequentially converted into a digital amount by an analog / digital converter (hereinafter referred to as A / D) 9 by the signal switch 8 and is processed by the processing unit 10 via the signal bus line 11.
Predetermined arithmetic processing is performed in the memory, the result is stored in the memory 13, and the interface (hereinafter referred to as I / F) 12
Is output to an output / display unit 17 such as a CRT or a printer. Furthermore, an alarm 18 or the like is output to the outside according to the diagnosis result of the device.

The signal from the humidity sensor 16 is converted into a digital amount by the A / D 14 via the I / F 15, and is taken into the processing unit 10.

The high-frequency CT3 is sensitive to only high-frequency signals flowing on the primary side.
The electric charge of the partial discharge generated in the container of S1 becomes a high frequency pulse signal and flows to the ground from the ground line, so high frequency CT3
However, the sensitivity is extremely low for low frequencies such as commercial frequencies.

Next, the operation of this embodiment will be described with reference to FIG. 3, FIG. 4, FIG.
It will be described with reference to the drawings.

With reference to a clock signal (not shown) in the processing unit 10, the signals of all input channels are acquired at regular time intervals. For example, in FIG. 3, RST is set between arbitrary time t and Δt up to t + Δt after a fixed time interval.
The maximum value P _R , P _S , and P _{T of the} amplitude of the phase channel signal is taken in as the discharge charge amount during that period. Normally, the starting point of time t is preferably determined by synchronizing with the reference phase, and the voltage zero point of the system is used as the starting point, for example, I to IV as shown in the figure.
By dividing into zones, the relationship with the voltage phase at the time of discharge occurrence can be seen, and information useful for estimating the cause of abnormality can be obtained. That is, it is possible to determine whether the cause of the abnormality is in the insulator or the contact failure of the contactor of the switch is the cause of abnormality, etc., depending on which of the zones I to IV the internal partial discharge is detected. Become. In addition, v in FIG. 3 shows a system voltage.

Now, as shown in FIG. 3, when the discharge amount is detected in each phase, the function of the present invention for determining whether this is due to external noise such as air corona or true internal partial discharge is described below. This will be described with reference to the flow charts of FIG. 4, FIG. 1 and FIG.
First, at 31 in FIG. 4, the humidity of the ambient atmosphere is measured by the humidity sensor 16, and based on this, the coefficient α is determined at 32. 33
Then, after calculating the discharge amount between time divisions Δt for each input channel and converting it into a digital amount, at 40, whether the measured discharge is due to a true internal partial discharge generated inside the device,
Determine whether it is external noise such as air corona. This determination will be described in detail later with reference to FIG. Those which are determined to be internal discharge are added to the counter at 34, and it is determined at 35 whether or not continuous measurement for a predetermined measurement period is completed. When the measurement is completed, the abnormality diagnosis is started at 36. Here, for example, the measurement period is T minutes, the divided time obtained by dividing the measurement time is Δt minutes,
When the number of divided time zones determined to have internal discharge during this period is m, the discharge occurrence rate β is calculated as β = m · Δt / T, and when β exceeds the set value, the internal discharge abnormality occurs. It is diagnosed as present, and at 37, alarm, display and output are performed.

Next, FIG. 1 shows a decision flow chart of the decision at 40. The basis of the determination is to compare the discharge amount detected in the self-phase with the discharge amount of the other phase, as a reference. Normally, the probability that true internal partial discharges due to internal abnormalities will occur simultaneously in multiple phases is extremely small.Therefore, the division time period in which the discharge amount of a specified amount or more is detected in other phases at the same time is due to external noise. Can be determined. For example, in the state shown in FIG.
determination between t + Delta] t, in the case of determining the R-phase, and the discharge amount P _R of its own phase, the coefficient alpha (0 determined by the humidity <
Based on the product α · P _R with α <1.0), the comparison with the discharge amount P _S of the other phase, that is, the S phase is performed at 41, and the comparison with the discharge amount P _T of the T phase is performed at 42. When neither of the discharges exceeds α · P _R, it is determined at 44 that an internal partial discharge of P _R amount has occurred in the R phase, and at 46, an abnormal treatment is performed. Otherwise, at 43, it is determined that the R-phase P _R discharge is due to external noise, and at 45, normal (no abnormality) treatment is performed.

The above operation is compared and judged for all the signals of the input channels which are related to each other during the time of Δt, and this is determined by Δ
The measurement is continuously performed at the t pitch for the measurement period T. This operation is executed at high speed by the function of the processing unit 10 according to the program stored in the memory 13 in FIG.

The coefficient α may be determined as a function of humidity as shown in FIG. 5, for example. This function is the structure of the electric power equipment to be diagnosed, and the characteristics of the substation as a whole, that is, whether it is a substation with many steel towers (a lot of aerial power equipment) or a substation with many power equipment in a closed round container, Alternatively, it should be set after considering the location conditions, that is, the likelihood of external noise such as aerial corona depending on whether the power equipment is in a city with a lot of radio waves or in the countryside. .

According to the present embodiment, the combination of the high frequency CT (partial discharge sensor) attached to the ground wire and the humidity sensor that detects the ambient humidity stops the monitoring function even in the case where there is a lot of corona in the air such as during rainfall. Without this, it is possible to diagnose the presence or absence of internal partial discharge of the device with high sensitivity.

Next, FIG. 6 compares a conventional example and an embodiment of the present invention in the case where an abnormality is detected by a partial discharge detection sensor attached to the ground line. In the figure, the threshold value of the discharge detection sensor is fixed to 500 pc in the past, and the discharge amount in the figure is 500 p for the S phase only.
Since it is more than c, it is diagnosed as abnormal.

On the other hand, in the present embodiment, first, the humidity at the time of determination is detected by the humidity detection sensor, and the coefficient α
Is determined. This coefficient α is predetermined as a function of humidity. This function is defined by the environment in which the GIS to be diagnosed is grounded. That is
As for the type of substation where GIS is installed, there are many aerial power devices and many steel towers, or many closed power devices and many round containers. It is defined by various environments such as whether it is mountainous or flat, and whether it is a substation in the city or a substation in the countryside.

Now assume that the humidity is 90% and the determined coefficient α is 0.6. Compare the quantity of 300 obtained by multiplying the discharge quantity 500pc detected from the S phase by 0.6 to the discharge quantity detected from the other R and T phases. Both R and T phases are not less than 300.
Since it is 450 pc and 300 pc, it is determined that the S-phase discharge amount is not a true internal partial discharge. Similarly, the amount of 270 obtained by multiplying the discharge amount of R phase of 450 pc by 0.6 is also compared with the discharge amount of other ST phases. At this time as well, neither 500 pc nor 300 pc is smaller than the amount 270 obtained by multiplication, so that it is determined that the R-phase discharge amount is not a true internal partial discharge. Similarly, the numbers 180 and 450 pc obtained by multiplying the T phase and
It is judged that the amount of discharge of the T phase is not due to the true internal partial discharge because 500 pc is compared and neither is smaller.

It is common sense that the discharge amounts shown in the table are detected for all R-phase, S-phase, and T-phase, and that these discharge amounts are not due to true internal discharge. That is, it is extremely unlikely that a true internal partial discharge indicating an abnormality will occur simultaneously in all three phases. Therefore, it is correct to determine that no abnormality has occurred in each phase, that is, it is normal. In the conventional example, since it is determined that the S phase has an abnormality, it means that an incorrect determination is made. In this example, all the phases are determined to be normal, and the correct determination is made.

As described above, according to this embodiment, the coefficient α at the time of determination, that is, at each time can be determined by the detection signal from the humidity detection sensor, and the discharge amounts of the respective phases can be compared finely. Therefore, it is possible to accurately determine whether the discharge amount is due to internal partial discharge or due to external noise such as air corona. This determination can be accurately made even in the case of extremely high humidity such as in the case of rain. Further, compared to the conventional method in which the threshold value of the partial discharge detection sensor is simply set, the judgment criterion (that is, the discharge amount α
The multiplied amount) appropriately changes at each time of the determination, and the coefficient α that determines the reference can also change depending on the humidity as a function of the humidity. Therefore, even when operating as an unattended diagnostic device constantly, the device of this embodiment can be operated with increased detection sensitivity of the sensor. Therefore, the reliability of diagnosis is increased. In addition, compared to the conventional method that combines a plurality of sensors of different types, that is, a sensor that detects the amount of discharge and a sensor that detects the vibration, that is, the sound of the container wall, to increase the reliability of diagnosis, At the same time, it is possible to reduce the cost, and at the same time, since the sensor for detecting the sound is not used, the signal processing from the sensor is simple and the device cost can be suppressed.

In this case, the digitization of the discharge amount is calculated on the basis of the maximum value for each division time of a predetermined width obtained by dividing the measurement period T, and this division is sufficiently subdivided in comparison with the pitch of the discharge repetition to obtain a plurality of correlations. The determination based on the presence or absence of simultaneous occurrence of is more effective.

Also, the ground wire to which the partial discharge detection sensor is attached is
Consider how the effects of external noise appear, for example, selecting the grounding line between adjacent phases of the same line of GIS, from the aspect of the device configuration, and select it arbitrarily according to the power device to be diagnosed. This allows a more reliable comparison.

Since the function of the coefficient α determined by the humidity has a variable factor depending on the shape of the electric power device to be diagnosed, the overall configuration, etc., it is preferable to input the function to the monitoring device based on the on-site measurement data during actual operation.

〔The invention's effect〕

According to the partial discharge diagnostic device of the present invention, the internal abnormality of the electric power equipment housed in the container is diagnosed using the partial discharge detection sensor without using the sound or sensor, so that the sound noise caused by raindrops hitting the container wall is reduced. No hassle. Moreover, the number of sensors can be reduced because the sound sensor is not used. Further, even if external noise such as corona in the air is generated, the discharge amounts of the respective phases are compared with each other and the amount obtained by multiplying the discharge amount of each phase by a coefficient is used as a reference for the comparison, thereby making a fine comparison. Further, the coefficient is determined according to the humidity at the time of the determination, and an accurate comparison can be performed to correctly determine whether or not the internal partial discharge is true. This determination can be performed even when the humidity is high, and when the humidity is high, the inconvenience of having to stop the diagnostic function in order to prevent malfunction is eliminated.

[Brief description of drawings]

FIG. 1 is a flow chart showing a comparison with the discharge amount of another phase in the device according to one embodiment of the present invention, FIG. 2 is a block configuration diagram of the device of this embodiment, and FIG. 3 is time of each phase. FIG. 4 is a diagram showing division, FIG. 4 is a flow chart showing the determination procedure of the present embodiment, and FIG.
FIG. 6 is a diagram showing a function of the coefficient .alpha. Determined by humidity, and FIG. 6 is a table for explaining the effect of the present embodiment by comparing the conventional determination and the determination of this embodiment. 1 ... Monitored device (GIS), 2 ... Ground wire, 3 ... High-frequency CT, 4 ... Coaxial cable, 5 ... Wider, 6 ... Filter, 7 ... Peak hold circuit, 8 ... Signal switch,
9 …… A / D converter, 10 …… Processing unit, 11 …… Signal bus line, 12 …… Interface (I / F), 13 …… Memory, 14 …… A / D converter, 15 …… Interface (I /
F), 16 ... Humidity sensor, 17 ... Output indicator, 18 ...
Alarm, 20 ... Diagnostic device.

Claims (1)

(57) [Claims] 1. A partial discharge diagnostic apparatus for detecting an partial discharge and diagnosing an abnormality inside an electric power device which is an AC power device and is housed in an independent container for each phase, and is provided for each phase container. Partial discharge detection sensor attached to the ground line, the amount obtained by multiplying the discharge amount detected from one phase by a coefficient α (0 <α <1.0) and the discharge amount detected from the other phase And a means for comparing with, an output means for issuing an abnormal signal by determining that the internal partial discharge is true only when the discharge amount of the other phase is small, a humidity detection sensor, and is defined as a function of humidity. And a coefficient determining unit that determines the coefficient α according to the humidity at the time of determination based on a detection signal from the humidity detection sensor.