JP7510370B2 - Method and system for monitoring operation of stationary electromagnetic devices - Google Patents

Description

The present invention relates to a method and system for monitoring the operation of stationary electromagnetic equipment, and a current measurement unit used therein.

Transformers and other static electromagnetic equipment used to convert transmission voltages in power systems have two windings, one for high voltage and one for low voltage, wound around an iron core made of soft magnetic materials such as oriented silicon steel and amorphous alloys whose main component is iron. To maintain electrical insulation between the windings, which are subjected to high voltage, and between the windings and the iron core, the iron core and windings of large-capacity static electromagnetic equipment are generally covered with insulating materials such as paper and housed in a tank filled with oil, gas, etc.

Once installed, static electromagnetic equipment must continue to operate for decades. As a result, the iron core, windings, and insulating materials of static electromagnetic equipment deform and deteriorate over time, leading to breakdowns, mainly caused by insulation breakdown, which ultimately brings about the end of the product's life.

Therefore, technology is being developed to measure and monitor various physical quantities of stationary electromagnetic equipment in operation, detect signs of failure in advance, and avoid the social disadvantages that would result from sudden power outages.

For example, Patent Document 1 discloses a technology for detecting electromagnetic waves emitted when an abnormality such as partial discharge occurs inside an electric power device in which a high-voltage conductor arranged inside an airtight container is supported by an insulator, using an antenna stored inside an antenna storage tube provided in the airtight container.

Patent Document 2 also discloses a technology that directly detects abnormalities in the amplitude and waveform of the magnetic flux density in the iron core of a stationary induction device by arranging a magnetic field detection means on the surface of the yoke portion of the iron core, excluding the portion where the winding is wound to become the magnetic legs, and preferably by arranging the magnetic field detection means at a certain distance from the surface of the bus bar connected to the low-voltage winding of the stationary induction device.

Furthermore, Patent Document 3 discloses a technology that uses an annular core with a gap to detect the magnetic flux passing through a transformer core with a gap, into which magnetic flux leaking from the gap flows, thereby directly detecting the magnetic flux passing through the transformer core from the outside, detecting bias magnetization, and using the technology for various controls according to the detected bias magnetization.

Japanese Patent No. 4860795 JP 2019-4056 A JP 2017-72481 A

In the technology disclosed in Patent Document 1, if partial discharge occurs on the opposite side of the antenna installed in the sealed container, it is difficult to detect the electromagnetic waves, and it is necessary to install multiple antennas in the sealed container.

In addition, the technology disclosed in Patent Document 2 can detect localized abnormalities in the leakage magnetic field near the iron core or busbar of a stationary induction device, but has the problem that it is difficult to detect abnormalities occurring in distant locations.

Furthermore, the technology disclosed in Patent Document 3 only detects magnetic flux leaking from the gap in the transformer core, making it difficult to detect abnormalities occurring in areas away from the gap.

The above issues can be improved by installing multiple detectors, but this will increase costs. Moreover, it is difficult to completely eliminate situations where abnormalities cannot be detected.

The objective of the present invention is to detect changes in leakage magnetic fields caused by abnormalities occurring at any point in a stationary electromagnetic device using additional components with a simple configuration.

The method for monitoring the operation of a stationary electromagnetic device of the present invention is a method for monitoring the operation of a stationary electromagnetic device including an iron core, a winding wound around the iron core, and a tank that houses the iron core and the winding using a determination unit, and includes the steps of: providing an annular conductive member on the outside of the tank; providing a current measurement unit on the conductive member; and determining whether or not there is an abnormality in the stationary electromagnetic device based on a change in the waveform of the circulating current.

According to the present invention, a change in leakage magnetic field due to an abnormality occurring at any point in a stationary electromagnetic device can be detected using an additional component with a simple configuration. Furthermore, since the additional component is installed outside the tank, it can also be applied to existing stationary electromagnetic devices.

FIG. 1 is a transparent perspective view showing a stationary electromagnetic device according to a first embodiment. 1 is a configuration diagram showing a system for monitoring the operation of a stationary electromagnetic device according to a first embodiment; 1 is a flow diagram showing a method for monitoring the operation of a stationary electromagnetic device according to a first embodiment; FIG. 2 is an enlarged configuration diagram showing an example of a current measuring unit in FIG. 1 . FIG. 11 is a perspective view showing a stationary electromagnetic device according to a second embodiment of the present invention. FIG. 11 is a configuration diagram showing a system for monitoring the operation of a stationary electromagnetic device according to a second embodiment. FIG. 11 is a perspective front view showing a stationary electromagnetic device according to a third embodiment. FIG. 11 is a transparent perspective view showing a stationary electromagnetic device according to a fourth embodiment. 8 is an enlarged cross-sectional view of a portion indicated by a dashed dotted line A in FIG. 7 .

The present invention relates to a technology that can easily diagnose the health of static electromagnetic equipment such as transformers and predict failures based on changes over time in the leakage magnetic field generated by the equipment.

Below, several examples of this disclosure are described in detail with reference to the drawings.

The configuration and effects of the first embodiment are explained using Figures 1 to 3.

Figure 1 is a perspective view showing the stationary electromagnetic device of this embodiment.

In this diagram, the static electromagnetic device 100 has a configuration in which U-phase, V-phase, and W-phase windings 12a, 12b, and 12c are provided on the magnetic legs of a three-phase iron core 11 (also simply called an "iron core") and housed inside a metal tank 1. The three-phase iron core 11 is made of soft magnetic materials such as directional silicon steel plate and amorphous alloys whose main component is iron. The windings 12a, 12b, and 12c are each wound in two overlapping systems, one for the low voltage side and one for the high voltage side. The inside of the tank 1 is filled with oil, gas, etc. to ensure electrical insulation.

In this diagram, one annular conductor 2 is provided on the outside of the tank 1. More specifically, the annular conductor 2 is wound around the outer periphery (side surface) of the tank 1 in a ring shape. Therefore, the annular conductor 2 can be called an "annular conductive member." A current measuring means 3a (current measuring unit) is provided at least at one location on the annular conductor 2. In this embodiment, the annular conductor 2 and the current measuring means 3a are additional components.

In a typical stationary electromagnetic device 100, the annular conductor 2 and the current measuring means 3a are not provided. Therefore, the method for monitoring the operation of a stationary electromagnetic device described below may include a step of attaching the annular conductor 2 and the current measuring means 3a to a predetermined position.

When the two windings 12a, 12b, and 12c are connected to a power system and a load, respectively, current flows through the windings 12a, 12b, and 12c, generating a leakage magnetic field 13. As the leakage magnetic field 13 interlinks with the annular conductor 2, a circulating current 2a flows through the annular conductor 2. The current measuring means 3a acquires the time waveform of the circulating current 2a.

Figure 2A is a configuration diagram showing a system for monitoring the operation of stationary electromagnetic devices according to this embodiment.

As shown in this diagram, the operation monitoring system for stationary electromagnetic equipment includes a current measuring means 3a (current measuring unit), a storage means 52 (database), a difference signal generating and comparing means 54 (determination unit), and a display and notification means 58 (display unit). In addition, a load current monitoring means 56 (load current measuring unit) and a temperature measuring means 57 (temperature measuring unit) installed in the stationary electromagnetic equipment may be used.

A plurality of circulating current waveforms acquired under different conditions regarding the load factor and temperature of the stationary electromagnetic equipment are stored in the storage means 52 as a data group 30. The difference signal generating and comparing means 54 (determination unit) calculates the difference I-I ₀ described later and makes a predetermined determination.

Figure 2B is a flow diagram showing a method for monitoring the operation of a stationary electromagnetic device according to this embodiment.

In this figure, first, when the stationary electromagnetic equipment starts operating, the circulating current waveform _I0 in the initial state acquired by the current measuring means 3a is stored in the storage means 52 (S110). At this time, a plurality of circulating current waveforms acquired under different conditions regarding the load factor and temperature of the stationary electromagnetic equipment are classified into a data group 30.

Next, after the stationary electromagnetic equipment starts operating, the circulating current waveform I obtained successively is input to the difference signal generating and comparing means 54 (S120). With reference to the load rate obtained by the load current monitoring means 56 provided in the stationary electromagnetic equipment and the temperature obtained by the temperature measuring means 57, the circulating current waveform _I0 in the initial state that matches the load rate and temperature conditions is read from the storage means 52 to the difference signal generating and comparing means 54 (S130). The difference signal generating and comparing means 54 calculates the difference I- _I0 between the two circulating current waveforms I and _I0 (S140).

The difference signal generating and comparing means 54 then judges whether the change in the waveform is equal to or greater than a preset reference value from the difference I-I ₀ (S150). If it is judged to be equal to or greater than the predetermined reference value, a signal is sent to the display and notifying means 58 (display unit) to notify of an abnormality (S160). The display unit may be a mobile terminal, a personal computer (PC), or the like.

The notification of an abnormality may be made without displaying it on the display unit, for example, by sounding a buzzer.

Furthermore, the above circulating current waveform _I0 is not necessarily limited to the "initial state", and the earlier circulating current waveform acquired before and after in time may be regarded as the "initial state" and used for calculation.

Figure 3 is an enlarged diagram showing an example of the current measuring means 3a in Figure 1.

The current measuring means 3a shown in this figure has a configuration in which a coil 33 is wound around a portion of the annular core 3. The annular core 3 is made of a soft magnetic material.

The annular core 3 is formed by laminating a large number of ribbon-shaped soft magnetic materials made of an amorphous alloy mainly composed of iron, and a connection part 32 is formed at one end of the ribbon using a structure such as a lap joint. With this configuration, the current measuring means 3a can be easily attached to the annular conductor 2 shown in FIG. 1 by opening the connection part 32. Furthermore, the current measuring means 3a can be replaced or added without processing or replacing the annular conductor 2.

In summary, the annular core 3 has a connection portion 32 configured so that the ring can be opened and attached to the annular conductor 2.

When an AC current crosses the annular core 3, a proportional AC voltage V is generated across the coil 33. By measuring this, the circulating current waveform I is obtained.

Electromagnetic analysis of a transformer of several tens of megawatts has shown that a current of several tens of amperes flows through the annular conductor 2. Therefore, it is quite possible to detect changes in the waveform of the static electromagnetic device 100 (transformer) using the current measuring means 3a of this embodiment.

The configuration and effects of the second embodiment will be described with reference to Figures 4 and 5. Note that descriptions of parts that overlap with the first embodiment will be omitted.

Figure 4 is a perspective view showing the stationary electromagnetic device of this embodiment.

In this figure, three annular conductors 2 are provided in parallel on the outside of the tank 1. Current measuring means 3a, 3b, and 3c are provided at at least one location on each of the annular conductors 2. In this embodiment, the annular conductors 2 and the current measuring means 3a, 3b, and 3c are additional components.

Figure 5 is a configuration diagram showing the operation monitoring system for stationary electromagnetic devices in this embodiment.

As shown in the figure, current measuring means 3a, 3b, and 3c acquire circulating current waveforms _Ia , _Ib , and _Ic , respectively.

The method for monitoring the operation of stationary electromagnetic equipment is basically the same as that shown in Figure 2B, so only the differences will be explained below.

When the stationary electromagnetic device starts operating, the initial state circulating current waveforms I _a0 , I _b0 , and I _c0 acquired by the current measuring means 3 a , 3 b , and 3 c , respectively, are stored in the storage means 52 .

As for the differences, _Ia - _Ia0 , _Ib - _Ib0 , and _Ic - _Ic0 are calculated, and it is determined whether each of them is equal to or greater than a predetermined reference value.

In this embodiment, the change over time in the leakage magnetic field 13 can be detected with higher accuracy than in the first embodiment, and the accuracy of detecting abnormalities in stationary electromagnetic equipment can be improved.

Note that in Examples 1 and 2, the static electromagnetic device having one and three annular conductors 2 is described, but the static electromagnetic device of the present disclosure is not limited to these, and may have two annular conductors 2, or four or more annular conductors 2.

The configuration and effects of Example 3 are explained using Figure 6.

Figure 6 is a perspective front view showing a stationary electromagnetic device having the same configuration as Figure 4. Explanations of the same reference numerals as Figure 4 are omitted.

In this embodiment, the method for calculating the difference is different from that in embodiment 2.

As shown in the graph on the left side of Fig. 6, the mutual differences Ia- _Ib , Ib-Ic, and Ic _{- Ia} between the three sets of circulating current waveforms _Ia , _Ib , and _Ic acquired by the current measuring means _3a , _3b , and _3c are calculated by the difference signal generating and comparing means 54 in Fig. 5. Then, from these differences Ia _{-Ib , Ib} - _Ic , and _Ic - _Ia , it is determined whether the change in the waveform is equal to or greater than a preset reference value. In other words, the change in the waveform of the circulating current is determined from the difference in the waveforms for two of the three conductive members.

In FIG. 6, when the U-phase winding 12a shifts as shown by the dashed line and the initial leakage magnetic field 13 (solid line) changes to leakage magnetic field 13a (dashed line), an abnormality occurs, which can be detected quickly and easily without using the initial circulating current waveform stored as data group 30 in memory means 52.

The configuration and effects of Example 4 are explained using Figures 7 and 8.

Explanation of symbols that are the same as those described in the explanations of Examples 1 to 3 will be omitted.

Figure 7 is a perspective view showing the stationary electromagnetic device of this embodiment.

In this figure, three structural members 21 configured in a ring shape are provided on the outside of the tank 1 of the stationary electromagnetic device 200. The structural members 21 are formed of a conductive material. In this embodiment, the structural members 21 are provided to reinforce the tank 1. In other words, the structural members 21 are components (reinforcements) of the tank 1. Current measuring means 3a, 3b, and 3c are attached to at least one location of each of the structural members 21. Thus, the structural members 21 can be called "ring-shaped conductive members." Therefore, in this embodiment, the method for monitoring the operation of the stationary electromagnetic device may include a step of attaching the current measuring means 3a, 3b, and 3c to predetermined locations of the structural members 21 that have been provided in advance. In this embodiment, the current measuring means 3a, 3b, and 3c are additional parts.

The current measuring means 3a, 3b, and 3c are capable of acquiring the time waveform of the circulating current 2a flowing through the structural material 21. The method of detecting an abnormality in the stationary electromagnetic device 200 from these circulating current waveforms and the method of notifying the abnormality are the same as those in the first to third embodiments.

In this figure, an example is shown in which there are three structural members 21, but the static electromagnetic device of the present disclosure is not limited to this, and there may be two structural members 21, or four or more structural members 21.

Figure 8 is an enlarged cross-sectional view of the portion indicated by dashed line A in Figure 7.

As shown in FIG. 8, the structural material 21 is provided for the purpose of improving the strength of the tank 1, and the two are connected at a welded portion 1a. The welded portion 1a is provided partially as shown in the figure. This increases the electrical resistance between the tank 1 and the structural material 21, and most of the circulating current 2a flows within the structural material 21.

Therefore, in this embodiment, as in the first to third embodiments, it is possible to detect abnormalities in stationary electromagnetic equipment. Furthermore, in this embodiment, since there is no need to provide a new conductive material that surrounds the tank 1 in a ring shape, it is possible to build an operation monitoring system for stationary electromagnetic equipment at minimal cost.

Even in a configuration in which the structural material 21 is installed on the tank 1 via the welded portion 1a as in this embodiment, it is still possible to detect changes in the waveform of the stationary electromagnetic device 200 using the current measuring means 3a, 3b, and 3c.

The structural material 21 may be installed not only by connecting it to the tank 1 by welding as described above, but also by clamping the tank 1. A spring or the like may be used as a clamping means. Also, a convex or concave portion may be provided on the tank 1, and the structural material 21 may be installed so as to be hooked onto the convex or concave portion. Even in this case, it is desirable that the tank 1 and the structural material 21 are configured so as to be in partial contact with each other.

The multiple examples described above do not limit the configuration of the present disclosure, and the effects of the configuration of the present disclosure can be obtained in the same way even if any multiple examples are combined.

In the above explanation, a static electromagnetic device such as a transformer is given as an example, but the configuration of the present disclosure is not limited to this, and can also be applied to motors (electric motors) that have moving parts such as rotating parts, housings for manipulators, etc.

1: Tank, 1a: Welded part, 2: Annular conductor, 2a: Circulating current, 3: Annular core, 3a, 3b, 3c: Current measuring means, 11: Three-phase core, 12a, 12b, 12c: Windings, 13, 13a: Leakage magnetic field, 21: Structural material, 30: Data group, 32: Connection part, 33: Coil.

Claims (13)

A method for monitoring an operation of a stationary electromagnetic device including an iron core, a winding wound around the iron core, and a tank containing the iron core and the winding, using a determination unit, comprising:
a ring-shaped conductive member is provided on the outside of the tank;
The conductive member is provided with a current measuring unit;
the current measuring unit measuring a circulating current flowing through the conductive member;
The determination unit determines whether or not there is an abnormality in the stationary electromagnetic equipment from a change in the waveform of the circulating current. The method for monitoring the operation of a stationary electromagnetic device according to claim 1, wherein the conductive member is a component of the tank. the change in the waveform of the circulating current is a difference in the waveform at different times;
2. The method for monitoring an operation of a stationary electromagnetic device according to claim 1, wherein the determining unit calculates the difference, and determines that the abnormality exists when the difference is equal to or greater than a predetermined reference value. The method for monitoring the operation of a stationary electromagnetic device according to claim 3, wherein the determination unit calculates the difference using the waveform of the circulating current that matches the load factor and temperature conditions of the stationary electromagnetic device. A plurality of the conductive members are provided on the outside of the tank,
the current measuring unit is provided on each of the plurality of conductive members,
the change in the waveform of the circulating current is a difference in the waveform for two of the plurality of conductive members;
2. The method for monitoring an operation of a stationary electromagnetic device according to claim 1, wherein the determining unit calculates the difference, and determines that the abnormality exists when the difference is equal to or greater than a predetermined reference value. 2. The method for monitoring the operation of a stationary electromagnetic device according to claim 1, wherein , when the determination unit determines that there is an abnormality, the determination unit notifies a display unit of the abnormality. A system for monitoring the operation of a stationary electromagnetic device including an iron core, a winding wound around the iron core, and a tank containing the iron core and the winding,
a current measuring unit provided on an annular conductive member provided on the outside of the tank;
A determination unit,
The current measuring unit measures a circulating current flowing through the conductive member;
The determination unit determines whether or not there is an abnormality in the stationary electromagnetic device based on a change in the waveform of the circulating current. The stationary electromagnetic device operation monitoring system according to claim 7, wherein the conductive member is a component of the tank. The stationary electromagnetic device operation monitoring system according to claim 8, wherein the conductive member and the tank are configured to be in partial contact with each other. The stationary electromagnetic device operation monitoring system according to claim 9, wherein a partial weld is provided between the conductive member and the tank. the change in the waveform of the circulating current is a difference in the waveform at different times;
8. The system for monitoring the operation of a stationary electromagnetic device according to claim 7, wherein the determining unit calculates the difference, and determines that the abnormality exists when the difference is equal to or greater than a predetermined reference value. The stationary electromagnetic device operation monitoring system according to claim 11, wherein the determination unit calculates the difference using the waveform of the circulating current that matches the load factor and temperature conditions of the stationary electromagnetic device. A plurality of the conductive members are provided on the outside of the tank,
the current measuring unit is provided on each of the plurality of conductive members,
the change in the waveform of the circulating current is a difference in the waveform for two of the plurality of conductive members;
8. The system for monitoring the operation of a stationary electromagnetic device according to claim 7, wherein the determining unit calculates the difference, and determines that the abnormality exists when the difference is equal to or greater than a predetermined reference value.

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