JP5414413B2 - Partial discharge diagnostic method and partial discharge diagnostic device for gas insulated switchgear - Google Patents

Description

  The present invention relates to a partial discharge diagnostic method and a partial discharge diagnostic device for a gas insulated switchgear.

  In the conventional partial discharge diagnosis method for electric power equipment, as in Patent Document 1, parameters such as discharge frequency n, discharge charge amount q, discharge generation phase φ are extracted from a partial discharge signal detected by means such as a sensor, The diagnosis of partial discharge is carried out according to the distribution of each parameter.

JP-A-6-34696

  The conventional method as described above needs to perform diagnosis by reading the correlation from a plurality of parameters such as φ-q distribution and φ-qn distribution. This is a method that is more efficient and simplified than diagnosing by observing the original discharge signal, but it is still difficult for non-experts and requires knowledge and experience.

  Further, in the conventional method as described above, when performing automatic diagnosis by an algorithm, there is a problem that since the number of parameters is plural, the algorithm is complicated and difficult to construct.

  The present invention has been made in view of the above problems, and does not require skill in diagnosis of partial discharge, and it is easy to construct an algorithm for automatic diagnosis. An object is to provide a partial discharge diagnostic apparatus.

  In order to solve the above-described problems and achieve the object, a partial discharge diagnosis method for a gas-insulated switchgear according to the present invention includes a gas-insulated switchgear in which a central conductor is housed in a metal container filled with an insulating gas. And a step of detecting, by a sensor, an electromagnetic wave radiated from a partial discharge discharge power source in the metal container, and a step-down voltage applied to the central conductor to a predetermined voltage. Obtaining the step, separating the noise from the electromagnetic wave signal output from the sensor and detecting the partial discharge signal, and for all the partial discharge signals detected within a predetermined time, based on the applied voltage signal. Then, by counting the occurrence frequency of the partial discharge with respect to the position on the applied potential phase-signal intensity plane, a discharge map representing the applied potential phase-signal intensity-occurrence frequency distribution is created. And calculating a dynamic center of gravity when the generation frequency is regarded as mass for a region that is a region representing a dense pattern of discharge signals on the applied phase-signal intensity plane; and Outputting the value of the center of gravity as a diagnosis result.

  According to the present invention, since the partial discharge can be diagnosed based on the center of gravity when the occurrence frequency of the partial discharge is regarded as the mass, the diagnosis is simplified and no skill is required. There is an effect that it is easy to construct an algorithm for.

FIG. 1 is a schematic diagram illustrating a configuration of a partial discharge diagnostic device for a gas-insulated switchgear according to a first embodiment. FIG. 2 is a diagram for explaining a discharge map generation method. FIG. 3 is an example of a discharge map showing the region and the center of gravity. FIG. 4 is a diagram showing the transition of the center of gravity with respect to the change in the applied voltage. FIG. 5 is a diagram showing a transition of density with respect to a change in applied voltage. FIG. 6 is a functional block diagram for partial discharge diagnosis processing realized by a computer.

  Embodiments of a partial discharge diagnostic method and a partial discharge diagnostic device for a gas insulated switchgear according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram showing a configuration of a partial discharge diagnostic device of a gas insulated switchgear according to the present embodiment. In FIG. 1, as main components of the gas insulated switchgear, cylindrical metal containers 1, 2 that are filled with an insulating gas and connected to each other, and stored in these metal containers 1, 2 are charged. The center conductor 3 to be electrified, the metal containers 1 and 2 are partitioned into a plurality of gas spaces, the spacer 4 made of an insulator for supporting the center conductor 3, the power transmission / distribution circuit system (not shown), and the gas A bushing 5 for connecting an insulated switchgear is shown. Depending on the power transmission / distribution circuit system in which the gas insulated switchgear is incorporated, a cable head may be attached instead of the bushing 5.

  In FIG. 1, as main components of the partial discharge diagnostic apparatus, a sensor 6 for detecting an electromagnetic wave signal, a signal amplifier 7 connected to the sensor 6, and an A / D converter connected to the signal amplifier 7 are used. 8, a voltage divider 9 as an applied voltage signal acquisition unit that divides and outputs an applied voltage applied to the center conductor 3, an A / D converter 10 connected to the voltage divider 9, and A A computer 11 is shown as a data processing unit to which both outputs of the / D converters 8 and 10 are input.

  The sensor 6 is a partial discharge sensor for measuring an electromagnetic wave radiated from a partial discharge discharge source that occurs when an insulation defect exists in the gas insulated switchgear. In FIG. 1, the sensor 6 is illustrated as a sensor that detects electromagnetic waves leaking from the spacer 4 to the outside of the gas-insulated switchgear. For example, the sensor 6 is installed in the gas-insulated switchgear. Also good.

  The signal amplifier 7 has a function of amplifying the electromagnetic wave signal detected by the sensor 6. The analog signal amplified by the signal amplifier 7 is converted into a digital signal by the A / D converter 8, and this digital signal is sent to the computer 11.

  On the other hand, the voltage divider 9 steps down the applied voltage applied to the central conductor 3 to a predetermined voltage and outputs this signal to the A / D converter 10. The A / D converter 10 converts the output signal of the voltage divider 9 from an analog signal to a digital signal, and outputs the divided applied voltage signal to the computer 11 as a digital signal. The computer 11 uses the electromagnetic wave signal input from the A / D converter 8 and the applied voltage signal input from the A / D converter 10 to perform real-time processing or storage in a storage device (not shown). The partial discharge is diagnosed by post-processing.

  Next, the operation of the present embodiment will be described. Since the operation until the signal is input from the A / D converters 8 and 10 to the computer 11 is as described above, signal processing by the computer 11 will be described below. FIG. 6 is a functional block diagram for the partial discharge diagnosis process realized by the computer 11. As shown in FIG. 6, the computer 11 as a signal processing unit includes functions of a partial discharge signal detection unit 12, a discharge map generation unit 13, a center of gravity calculation unit 14, a discharge diagnosis unit 15, and the like.

  The partial discharge diagnostic apparatus according to the present embodiment processes a discharge signal with a certain time Tf as a processing unit. Tf can be set to, for example, about 30 seconds to 1 minute. The partial discharge signal detection unit 12 separates the electromagnetic wave signal input from the A / D converter 8 into noise and partial discharge signal, and extracts only the partial discharge signal as a processing target. There is no limitation on the separation method. For example, there is a method in which a certain signal intensity is used as a threshold, and a signal equal to or higher than the threshold is separated as a partial discharge signal.

  Next, based on the partial discharge signal output from the partial discharge signal detection unit 12 and the applied voltage signal output from the A / D converter 10, the discharge map generation unit 13 performs all the observations during Tf. For the partial discharge pulse, a discharge map is created by counting the occurrence frequency n (count number) of the partial discharge with respect to the position on the applied potential phase φ-discharge charge amount q plane. Note that the applied voltage phase φ is the phase of the applied voltage signal. Further, q may be a signal intensity proportional to the discharge charge amount.

  FIG. 2 is a diagram for explaining a discharge map generation method. As shown in FIG. 2, the mesh structure is constructed by dividing the φ axis and the q axis, for example, at regular intervals (the intervals are Δφ and Δq) on the potential applied phase φ-signal intensity q plane. A small area that is each square of the mesh is called a slot. Each slot is characterized by a representative value of (φ, q) coordinates and Δφ, Δq. The discharge map generator 13 determines a corresponding slot from the discharge generation phase and the signal intensity for each partial discharge pulse, and counts the number of occurrences for each slot. Then, the construction of the discharge map is completed by finishing counting all the partial discharge pulses generated during Tf. In FIG. 2, for example, in a slot described as “18”, it means that the partial discharge corresponding to the condition of this slot has occurred 18 times. When the discharge map is displayed, it can be displayed by a two-dimensional color map in which n is converted to an appropriate color scale or a three-dimensional map. In this way, one discharge map is created for each Tf.

  In the discharge map created in this way, the partial discharge signals are observed as dense signals due to their phase synchronism. That is, there is a correlation between the type of discharge source and the discharge generation phase, and there is a characteristic that the partial discharge signal appears as a dense pattern on the discharge map.

  Next, in the present embodiment, such a dense pattern of signals on the discharge map is defined as a region, and the centroid calculation unit 14 calculates the centroid for each region. Here, the center of gravity is a mechanical center of gravity when the occurrence frequency n is regarded as mass, and is calculated for each region. The center of gravity can be interpreted as a point where the information of the discharge signal is collected.

  Regardless of the region extraction method, the region may be extracted dynamically based on the actually obtained discharge map pattern, or the region may be defined in advance based on the expected discharge characteristics. May be. For example, the center of gravity calculation unit 14 may extract a connected region including slots whose n value is not 0 in the φ-q plane as a region, or simply divide into positive discharge and negative discharge. The φ-q plane may be divided into two regions (each region of 0 ≦ φ <π and π ≦ φ <2π) depending on whether the applied voltage is positive or negative.

  The calculation of the center of gravity can be performed, for example, by regarding the slot having the occurrence frequency n in the region as the mass point of the mass n and obtaining the mechanical center of gravity. Alternatively, each discharge pulse may be regarded as a mass point of mass 1 in the region, and the mechanical center of gravity may be obtained. The center of gravity is one index indicating the place where discharge is most active in the discharge signal distribution of φ−q−n, and is a point representing the region.

  Subsequently, the discharge diagnosis unit 15 outputs the value of the center of gravity calculated for each region as a diagnosis result. Moreover, the partial discharge diagnosis part 15 displays a discharge map like FIG. 3 with a display apparatus (not shown). FIG. 3 is an example of a discharge map showing the region and the center of gravity. In FIG. 3, the horizontal axis is the applied voltage phase (φ), the vertical axis is the signal intensity (q), and the discharge frequency (n) is indicated by the difference in hatching. From FIG. 3, it can be seen that the applied voltage phase of the center of gravity G is about 270 °. The operator can identify the type of discharge source from the applied potential phase value at the center of gravity, and can know the magnitude of discharge from the signal intensity at the center of gravity.

  In addition, the discharge diagnosis unit 15 can be given a function of automatically identifying the type of discharge source. In this case, the discharge diagnosis unit 15 holds a database that relates the type of discharge source and the discharge generation phase, compares the calculated phase of the center of gravity with this database, identifies the type of discharge source, The type of discharge source is output as the diagnosis result. This database is created in advance based on actual measurement, simulation, or the like (for example, see FIG. 4).

  Conventionally, the discharge source has been identified by focusing on the phase where discharge is active in the φ-n graph or the like based on the so-called Point on Wave concept. However, it is difficult for an unskilled person to specify a phase in which discharge is active in a distribution that is wide and fluctuates, and it is also difficult to handle automatic diagnosis with a computer.

  On the other hand, in this embodiment, due to the characteristic that the discharge signal appears as a certain dense pattern on the discharge map due to the phase synchronization, a cluster of closely distributed signals is defined as a region, and each region is geometrically and statistically Diagnosis is made by calculating the center of gravity, which is a parameter representing a characteristic.

  According to the present embodiment, one point representing the discharge signal called the center of gravity is extracted, and by focusing on this single point, diagnosis by Point on Wave can be performed, and simplification of discharge source identification can be realized. it can.

  Further, according to the present embodiment, it is not necessary to make a diagnosis by looking at a wide area on the discharge map as in the prior art, so that there is an effect that no skill is required.

  Further, according to the present embodiment, when performing automatic diagnosis by an algorithm, the center of gravity only needs to be calculated, so that the algorithm can be easily constructed. This automatic diagnosis can be realized by the computer 11 whose operation is controlled by a program in which the procedure of the above-described diagnosis method is described. The computer 11 includes a control device such as a CPU, a storage device such as a ROM (Read Only Memory) and a RAM, an external storage device such as an HDD, a display device such as a display device, and an input such as a keyboard and a mouse. A normal hardware configuration with the device can be used.

  Further, since the center of gravity is obtained from the averaging process of a plurality of discharge pulses, there is an effect that the robustness is high.

Embodiment 2. FIG.
In this embodiment, paying attention to the transition of the center of gravity with respect to a change in applied voltage, the degree of progress of discharge is diagnosed.

  FIG. 4 is a diagram showing the transition of the center of gravity with respect to the change in the applied voltage. In FIG. 4, the horizontal axis indicates the applied voltage phase, the vertical axis indicates the signal intensity, and the discharge source is, for example, a needle electrode and a floating electrode. Here, the needle electrode is a needle-like metal foreign object existing in the metal containers 1 and 2. The floating electrode is a metallic foreign object supported in a state where it floats on the central conductor 3 or the like via an insulator. For example, a part of the spacer is peeled off and falls onto the central conductor 3 and further onto this. This assumes that there are missing bolts.

  FIG. 4 is a graph showing the transition of the center of gravity when the applied voltage of the center conductor 3 is increased at regular intervals, for example, for two types of floating electrodes and needle electrodes. For floating electrode discharge, the transition direction of the center of gravity is indicated by an arrow. For example, the center of gravity of the discharge signal (region 1) that uses the floating electrode as a discharge power source changes in a substantially constant direction within the range of 0 to 90 ° as the applied voltage increases. Specifically, the transition direction is a direction in which the applied voltage phase decreases and the signal intensity increases, but the increase in signal intensity is slight and the change gradient is quite small. In addition, the center of gravity of the discharge signal (region 2) using another floating electrode as a discharge power source changes in a substantially constant direction within the range of 180 ° to 270 ° as the applied voltage increases. . Specifically, the transition direction is a direction in which the applied voltage phase decreases and the signal intensity increases, but the gradient of the change is larger than that in the region 1. Further, the center of gravity of the discharge signal (region 3) using the needle electrode as a discharge source hardly changes, and the applied potential phase is stopped at around 260 °.

As described above, at least for the floating electrode, the transition of the center of gravity is observed according to a certain proportional relationship with the change of the applied voltage. In addition, since the discharge progresses as the applied voltage increases,
For at least some types of discharge sources, the progress of discharge can be diagnosed by examining the transition of the center of gravity. For example, in FIG. 4, the discharge progress degree can be diagnosed by making the applied voltage phase correspond to the discharge progress degree. Specifically, for example, the applied voltage phase is compared with a specific value, and when the applied voltage phase is smaller than the specified value, it can be determined that the degree of progress of discharge is large.

  Therefore, in the present embodiment, the discharge diagnosis unit 15 periodically creates a discharge map and examines the change in the center of gravity over time. Specifically, a graph as shown in FIG. 4 is created, and the transition of the center of gravity on the potential applied phase-signal intensity plane is examined. That is, after the discharge signal is observed, the progress of the discharge can be diagnosed by periodically calculating the position of the center of gravity and examining the transition of the center of gravity. Note that while the gas insulated switchgear is in operation, the applied voltage is controlled to be constant. However, if the insulation performance deteriorates due to decomposition of the insulating gas due to the occurrence of partial discharge, the applied voltage is substantially reduced. For example, a transition of the center of gravity is observed for the floating electrode discharge.

  According to the present embodiment, by examining the transition of the center of gravity of the discharge signal, there is an effect that the progress of discharge can be diagnosed at least for some types of discharge sources.

Embodiment 3 FIG.
In the second embodiment, the method of diagnosing the progress of discharge based on the transition of the center of gravity with respect to the change in applied voltage has been described. However, no transition of the center of gravity was observed for the needle electrode discharge, and the method of the second embodiment could not be applied. In this embodiment, therefore, the progress of discharge is diagnosed by paying attention to density transition, which is another parameter.

  The density is calculated by dividing the total number of discharges in the region by the area representing the size of the region. That is, the density is the number of discharges per unit area. The area is an area on the φ-q plane and is represented by a physical quantity of φ · q. The area calculation method is not limited. For example, the area ΔS = Δφ × Δq of a single slot on the φ-q plane is obtained, and the total number of slots K in the region is calculated by integration with S × K. There are ways to find it.

  FIGS. 5A and 5B are diagrams showing a transition of density with respect to a change in applied voltage, where FIG. 5A shows a floating electrode discharge and FIG. 5B shows a needle electrode discharge. The horizontal axis is the applied voltage, and the vertical axis is the density.

  FIG. 5A is a graph showing changes in density accompanying changes in applied voltage for the two types of floating electrode discharges in FIG. 4, that is, floating electrode discharge (region 1) and floating electrode discharge (region 2). . As shown in the figure, the density of the floating electrode discharge (region 2) hardly changes, but the density of the floating electrode discharge (region 1) increases as the applied voltage increases. The degree of change is almost linear.

  FIG. 5B is a graph showing changes in density accompanying changes in applied voltage for the needle electrode discharge (region 3) in FIG. As shown in the figure, the density increases as the applied voltage increases. The degree of change is almost linear.

  As described in the second embodiment, the discharge progresses as the applied voltage increases. Further, as shown in FIG. 5, at least the needle electrode has a density transition as the applied voltage changes. Therefore, it is understood that the progress degree of the discharge can be diagnosed by examining the density transition of the needle electrode discharge in which the degree of discharge progress cannot be diagnosed depending on the transition of the center of gravity. For example, in FIG. 5B, the discharge progress degree can be diagnosed by making the density correspond to the discharge progress degree.

  In the present embodiment, the discharge diagnosis unit 15 periodically creates a discharge map and examines the density change with time. That is, after the discharge signal is observed, the position of the center of gravity is periodically calculated to check the transition of the center of gravity, and the density is calculated to check the density transition. As described above, the applied voltage is controlled to be constant during the operation of the gas insulated switchgear. However, if the insulation performance is degraded due to decomposition of the insulation gas due to the occurrence of partial discharge, the voltage is substantially imposed. The situation is the same as when the electric voltage is increased. For example, a transition in density is observed for the needle electrode discharge.

  According to the present embodiment, by examining the density transition in addition to the center-of-gravity transition described in the second embodiment, it is possible to diagnose the progress of discharge related to a wider discharge source.

  As described above, the present invention is useful as a partial discharge diagnostic method and a partial discharge diagnostic device for a gas insulated switchgear.

1, 2 Metal container 3 Central conductor 4 Spacer 5 Bushing 6 Sensor 7 Signal amplifier 8, 10 A / D converter 9 Voltage divider
11 Computer 12 Partial Discharge Signal Detection Unit 13 Discharge Map Generation Unit 14 Center of Gravity Calculation Unit 15 Discharge Diagnosis Unit

Claims (10)

A partial discharge diagnosis method for a gas insulated switchgear in which a central conductor is housed in a metal container filled with an insulating gas,
Detecting electromagnetic waves radiated from a partial discharge discharge source in the metal container with a sensor;
Reducing the applied voltage applied to the central conductor to a predetermined voltage to obtain an applied voltage signal;
Separating a noise from an electromagnetic wave signal output from the sensor to detect a partial discharge signal;
For all the partial discharge signals detected within a certain period of time, the frequency of occurrence of the partial discharge is counted with respect to the position on the applied phase-signal intensity plane based on the applied voltage signal. Creating a discharge map representing potential phase-signal intensity-occurrence frequency distribution;
For a region that is a region representing a dense pattern of discharge signals on the applied potential phase-signal intensity plane, calculating a dynamic center of gravity when the generation frequency is regarded as mass;
Outputting the value of the center of gravity as a diagnostic result;
A partial discharge diagnostic method for a gas-insulated switchgear characterized by comprising:   After calculating the center of gravity, using a database in which the type of discharge source and the applied phase are related, by comparing the database with the applied phase value of the center of gravity, the type of the discharge source is specified. The partial discharge diagnosis method for a gas insulated switchgear according to claim 1, wherein the identification result is output.   When creating the discharge map, the applied potential phase-signal intensity plane is divided into a plurality of small areas, and a corresponding small area is determined for each detected partial discharge signal. 3. The partial discharge diagnosis method for a gas insulated switchgear according to claim 1 or 2, wherein the occurrence frequency is counted every time.   The gas-insulated switchgear according to any one of claims 1 to 3, wherein a time-dependent change of the center of gravity is examined for each region, and the progress of partial discharge is diagnosed based on the transition of the center of gravity. Partial discharge diagnosis method.   Define the density of the region by dividing the total number of discharges in the region by the area of the region, examine the change over time in the density for each region, and diagnose the progress of partial discharge based on the density transition The partial discharge diagnosis method for a gas insulated switchgear according to claim 4, wherein: A partial discharge diagnostic device for a gas insulated switchgear in which a central conductor is housed in a metal container filled with an insulating gas,
A sensor capable of detecting an electromagnetic wave radiated from a partial discharge discharge source in the metal container;
An applied voltage signal acquisition unit that acquires an applied voltage applied to the central conductor by stepping down to a predetermined voltage;
A partial discharge signal detector for detecting a partial discharge signal from an electromagnetic wave signal output by the sensor;
For all the partial discharge signals detected within a certain period of time, the partial discharge is performed with respect to the position on the applied voltage phase-signal intensity plane based on the applied voltage signal output from the applied voltage signal acquisition unit. A discharge map generation unit that creates a discharge map representing the applied potential phase-signal intensity-occurrence frequency distribution by counting the occurrence frequency of
For a region that is a region representing a dense pattern of discharge signals on the applied voltage phase-signal intensity plane, a centroid calculating unit that calculates a dynamic centroid when the occurrence frequency is regarded as mass;
A discharge diagnosis unit that outputs the calculated value of the center of gravity as a diagnosis result; and
A partial discharge diagnostic device for a gas insulated switchgear characterized by comprising:   The discharge diagnosis unit has a database that associates the type of discharge source with the applied phase, and the discharge diagnosis unit compares the phase value of the center of gravity with the database to determine the type of discharge source. The partial discharge diagnosis apparatus for a gas insulated switchgear according to claim 6, wherein the identification result is output and the identification result is output.   The discharge map generation unit divides the potential applied phase-signal intensity plane into a plurality of small areas, determines a small area to which a discharge phase and a signal intensity of the detected partial discharge signal belong, and The partial discharge diagnosis device for a gas insulated switchgear according to claim 6 or 7, wherein the occurrence frequency is counted for each region.   9. The discharge diagnosis unit according to any one of claims 6 to 8, wherein the discharge diagnosis unit examines a temporal change of the center of gravity for each of the regions and diagnoses a progress degree of partial discharge based on the transition of the center of gravity. A partial discharge diagnostic device for a gas insulated switchgear according to claim.   The discharge diagnosis unit obtains the density of the region by dividing the total number of discharges in the region by the area of the region, examines the change over time in the density for each region, and determines the partial discharge based on the density transition. The partial discharge diagnosis device for a gas-insulated switchgear according to claim 9, wherein the degree of progress is diagnosed.

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