JP2009004801A - Current transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current transformer including an inexpensive Rogovski coil which protects current measurement not to be affected from any external magnetic field penetrating an opening formed at the center of a winding core, and thus can achieve high precise current measurement. <P>SOLUTION: The current transformer includes a multilayered printed circuit substrate 7 which has an opening 9 formed at the center thereof, a substrate front-surface 11a, a substrate back-surface 11b, and a plurality of substrate inner-layers 12a... sandwiched by the substrate front-surface 11a and the substrate back-surface 11b. In the front surface, the back surface, and the inner layer of each substrate, there are formed a layer having a metal foil which is composed of a plurality of metal foils 2a, 2b extending radially outwardly from a substantially center of the opening; and a layer having a metal foil which is composed of a metal foil 3a extending peripherally around a substantially center of the opening. Radially-extending metal foils between any two layers among the layers having a plurality of radially-extending metal foils are electrically connected by a plated hole which penetrates in the direction of the thickness of the printed circuit substrate, thereby forming one winding. The current transformer includes these (2×N+1) windings. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a current transformer and a current transformer system used for measuring the amount of main circuit alternating current supplied to a power transmission and transformation device, and more particularly to a current transformer that is digitized using a Rogowski coil. Related to the vessel.

  Generally, a through-type current transformer is often used to measure an alternating current supplied to a power transmission / transformer device or the like. A conventional through-type current transformer is a current transformer in which a secondary winding is wound around an annular winding core and a conductor through which a primary current to be measured is passed is passed through an opening in the center of the winding core. Such current transformers include those using an iron core as the winding core and those using a non-magnetic material. Among these, those using nonmagnetic materials are called air core current transformers or Rogowski coils, and can obtain excellent linear characteristics without saturation.

  FIG. 14 shows a configuration of a general Rogowski coil. The Rogowski coil 1 shown in FIG. 1 winds the winding 2 from a point P to a point Q at regular intervals over the entire circumference of the core 6 made of nonmagnetic material, and winds the return line 3 from the point Q to the point R. It is constituted by returning along the winding core in the direction opposite to the winding advance direction of 2. Usually, the return line 3 is returned through between the core 6 and the winding 2. Further, the conductor 5 through which the main circuit alternating current flows is passed through the opening 6 a of the core 6.

  At this time, a voltage is generated between the terminals 4 and 4 in proportion to the magnitude of the temporal change in the primary current passed through the conductor 5. Therefore, the primary current can be measured by integrating this voltage and multiplying by a constant determined by the shape of the coil. In the case of an ideal Rogowski coil, the voltage between the terminals 4 and 4 is not affected by a deviation between the conductor 5 and the center position of the core 6, a magnetic field outside the Rogowski coil, or the like.

  Here, an ideal Rogowski coil is (a) the winding interval (pitch) of the winding 2 is constant, (b) the area surrounded by the winding 2 is equal to the area surrounded by the return line 3 ( c) The cross-sectional area of the core 6 is constant over the entire circumference and is not affected by temperature, and (d) the winding 2 is completely wound over the entire circumference of the core 6 so that a missing portion is present. A Rogowski coil that has no characteristics.

  However, when a Rogowski coil as shown in FIG. 14 is manufactured, it is difficult to realize the condition (a) above, that is, to wind the winding 2 around the core 6 while maintaining a constant winding interval. . In order to achieve this, a constant winding interval can be maintained by providing a groove or protrusion for fixing the position of the winding 2 on the core 6. A device is required, and the price of Rogowski coil becomes extremely expensive.

  In order to solve this problem, a configuration of a Rogowski coil shown in FIG. 15 is conventionally considered. In the Rogowski coil shown in the figure, the metal foil 2e is formed on the front and back surfaces of the printed circuit board 7 having the opening 9 in the center so as to coincide with a plurality of straight lines extending radially from the center of the opening 9. ing. In addition, between the radial metal foil on one surface of the printed circuit board 7 and the radial metal foil on the opposite surface is electrically connected by a plated hole penetrating the printed circuit board 7, so that the winding 2 and the return path are connected. A line 3 is formed.

In the example shown in FIG. 15, the return line 3 also forms a winding, which increases the output voltage between the terminals 4 and 4 per unit current and unit frequency, thereby improving the sensitivity of the Rogowski coil. As for the winding advance direction, the winding 2 is clockwise, and the return line 3 is wound counterclockwise. (For example, refer to Patent Document 1.)
According to such a conventional technique, by applying a general printed circuit board manufacturing technique, it is possible to manufacture a Rogowski coil in which the winding interval between the winding 2 and the return line 3 is exactly constant. . Therefore, the above-described condition (a) can be realized to a considerable extent.
A Rogowski coil in which a winding is formed of a metal foil formed on a printed circuit board is hereinafter referred to as a printed circuit board type Rogowski coil.
Japanese Patent Laid-Open No. 6-176947 (page 3, FIGS. 1 and 2)

  By the way, in the conventional Rogowski coil mentioned above, the condition of (b) mentioned above, that is, the condition that the area surrounded by the winding 2 and the area surrounded by the return line 3 cannot be completely satisfied, and therefore the influence of the external magnetic field. This increases the error in current measurement.

  FIG. 16 shows a state in which a magnetic flux Φ due to an external magnetic field in a direction penetrating the central opening 6a of the core 6 is interlinked with the winding 2 of a general Rogowski coil 1 as shown in FIG. It is a schematic diagram. FIG. 17 is a schematic diagram showing a state in which the magnetic flux Φ by the same external magnetic field is linked to the return line 3 of the general Rogowski coil 1 as shown in FIG.

  In the voltage generated between the terminals 4 and 4 of the Rogowski coil 1 shown in FIG. 14, the winding advance direction of the winding 2 and the winding advance direction of the return line 3 are opposite, and therefore the point PQ shown in FIG. It is equal to the difference between the voltage generated between and the voltage generated between the points QR shown in FIG. Here, for example, if the magnetic flux Φ due to the external magnetic field is uniform over the entire surface of the Rogowski coil 1, the area A surrounded by the winding 2 in FIG. 16 is not equal to the area B surrounded by the return line 3 in FIG. In this case, a voltage due to the external magnetic field is generated between the terminals 4 and 4. Since this voltage is not related to the primary current that should be measured, it causes measurement errors.

  Factors that generate an external magnetic field include the following cases. For example, as shown in FIG. 18, when the conductor 5 is bent, or when there is a conductor 8 that is energized outside the Rogowski coil 1, or as shown in FIG. 19, the Rogowski coil For example, the conductor 5 is disposed obliquely with respect to 1. When the Rogowski coil 1 is applied to an actual power transmission / transformation device, it is impossible to completely eliminate the above-described factors. In addition, since the magnetic flux Φ due to an actual external magnetic field is not uniform, the influence is further complicated.

  By making the area A surrounded by the winding 2 and the area B surrounding the return line 3 equal, more preferably, the error can be reduced by making the shape of the winding 2 and the shape of the return line 3 exactly the same. Although it is possible, it is extremely difficult to avoid the influence of an external magnetic field in the general Rogowski coil 1 shown in FIG. It is.

  On the other hand, in the Rogowski coil 1 shown in FIG. 15, the influence of the external magnetic field can be considerably reduced, but the reason for the configuration is that the area surrounded by the return line 3 is smaller than the area surrounded by the winding 2. Therefore, it will be affected by the external magnetic field.

Now that the influence of the external magnetic field applied to the Rogowski coil has been described so far, another problem will be described here.
That is, as described above, it is possible to considerably reduce the influence of the external magnetic field by employing the Rogowski coil shown in FIG. 15. However, the general Rogowski coil shown in FIG. The problem is that it cannot be simply replaced with the Rogowski coil shown.

  The reason why the two cannot be simply replaced is the logo shown in FIG. 15 indicating the magnitude of the secondary output voltage of the Rogowski coil 1 with respect to the primary current (corresponding to the current transformation ratio in the case of an iron core type current transformer). This is because the level of the level of the general Rogowski coil shown in FIG.

  As is well known, the secondary output voltage of a Rogowski coil is proportional to the product of the number of coil turns and the cross-sectional area of one turn. In the general Rogowski coil 1 shown in FIG. 14, the secondary output voltage with respect to the rated primary current is usually several tens of volts. In the Rogowski coil 1 of FIG. 14, the cross-sectional area of one turn can be arbitrarily determined (as long as the installation space permits), and the number of turns of the coil is double and triple, and the required secondary output voltage is Since it can adjust so that it may be obtained, the secondary output voltage of several 10V is easily realizable.

  If a secondary output voltage of several tens of volts can be obtained from the Rogowski coil, noise will be generated between the substation equipment at the site where the Rogowski coil is installed and the main building where the protection control device is installed. It is possible to transmit an analog voltage signal without being greatly affected by (i.e., without being accompanied by signal deterioration that affects the protection control device).

  However, the Rogowski coil shown in FIG. 15 has a physical limit on the size of both the number of coil turns and the cross-sectional area of the turn because of the structural reason that the coil is formed of metal foil formed on the printed circuit board. Although it varies depending on the size of the substrate and the width of the metal foil, the maximum number of coil turns is about 1000 turns, and the manufacturing limit of the substrate thickness is about 5 mm to 6 mm at most for one-turn cross-sectional area. Limited.

  Therefore, the secondary output voltage of the Rogowski coil shown in FIG. 15 is limited to about 100 mV / kA at most. Even if 10 Rogowski coils are connected in series, the secondary output voltage is about 1 V / kA, and it is difficult to transmit an analog voltage signal to the main building of the electric station from the viewpoint of noise resistance.

  The present invention has been proposed in order to solve the above-described problems of the prior art. The purpose of the present invention is to provide an external magnetic field even when there is an external magnetic field penetrating the opening at the center of the core. An object of the present invention is to provide a current transformer having an inexpensive Rogowski coil that prevents current measurement from being affected and enables highly accurate current measurement.

  In order to achieve the above object, the invention according to claim 1 of the present invention has an opening through which a conductor penetrates in the center, and is sandwiched between the substrate surface, the substrate back surface, and the substrate surface and the substrate back surface. A plurality of metal foils each including a printed circuit board having a multilayer structure having a plurality of substrate inner layers, wherein the metal foils are arranged radially on the substrate front surface, the substrate back surface, and the substrate inner layer, with the center of the opening being substantially centered. And a layer formed by a circumferential metal foil in which the metal foil is substantially centered on the center of the opening, and among the layers having the plurality of radial metal foils, A radial metal foil between any two layers is electrically connected by a plated hole penetrating the printed circuit board in the thickness direction to form one winding, and the winding thus formed is (2 × N + 1) and has a printed circuit board Of the windings, (N + 1) windings and the remaining N windings are wound in opposite directions, and the (2 × N + 1) windings and the circumferential metal foil are electrically connected. The Rogowski coil is connected in series, and the winding direction of the circumferential metal foil is the same direction as the remaining N windings, and this is used as a return line.

  According to the present invention, the winding is constituted by the metal foil formed on the printed circuit board by the conventional general printed circuit board manufacturing technique, and an odd number of multi-winding Rogowski coils are obtained. Achieving error performance equivalent to that of a ski coil, and with a board size equivalent to that of a conventional printed circuit board type Rogowski coil, it is possible to obtain a secondary output voltage that is a multiple corresponding to the number of multiple windings. Improves noise resistance against the Rogowski coil.

  As described above, according to the present invention, a metal foil is formed on the outer substrate surface of the multilayer printed circuit board and the inner layer of the multilayer printed circuit board by applying a multilayer printed circuit board manufacturing technique of a general printed circuit board. A plurality of windings are formed by electrically connecting through the wire, and a metal foil serving as a return line is formed on the inner layer of the substrate, and the return line and the plurality of windings are electrically connected in series. In addition, since the radius of the winding is determined so that the area surrounded by the winding and the area surrounded by the return line are equal, it affects the external magnetic field that penetrates the central opening of the Rogowski coil. Therefore, it is possible to obtain an inexpensive current transformer that has excellent noise resistance and can perform highly accurate current measurement.

  Also, by combining a multi-winding Rogowski coil made of a printed circuit board and a sensor unit that converts the secondary output voltage of the Rogowski coil arranged in the vicinity thereof into a digital optical signal, the central opening of the Rogowski coil It is possible to obtain an inexpensive current transformer system that is not affected by an external magnetic field that penetrates the section, has excellent noise resistance, and can perform highly accurate current measurement.

  Embodiments of a current transformer according to the present invention will be described below with reference to the drawings. 1, 2 and 3 are diagrams showing the configuration of the Rogowski coil of the current transformer according to the first embodiment of the present invention. In this embodiment, a case where a double winding is formed as a winding on a printed circuit board having a five-layer structure will be described.

  In FIG. 1, a printed circuit board 7 is a printed circuit board having a five-layer structure including a substrate surface 11a, a substrate back surface 11b, and three substrate inner layers 12a, 12b, and 12c sandwiched between the substrate surface 11a and the substrate back surface 11b. . The printed circuit board 7 has a circular opening 9 at the center through which a conductor through which a main circuit alternating current flows is passed.

FIG. 2 is an external view of the printed circuit board 7 shown in FIG. 1 viewed from the central axis direction of the opening 9.
FIG. 3 is a schematic sectional view of the printed circuit board 7 shown in FIG. 1 cut along the line III-III and viewed in the direction of the arrow.

  In the Rogowski coil 1 of the current transformer according to the present embodiment, a plurality of linear radial metal foils 2a spreading radially around the center of the opening 9 on the substrate surface 11a (first layer) of the printed circuit board 7 are provided. The same radial metal foil 2b is formed on the substrate back surface 11b (fifth layer), and the radial metal foil 2a on the substrate surface 11a (first layer) and the radial metal foil 2b on the substrate back surface 11b (fifth layer) Are electrically connected by plated through holes 2c penetrating the printed board in the thickness direction.

  One winding 2 is formed on the printed circuit board 7 by the radial metal foil 2a, the radial metal foil 2b, and the through hole 2c.

Although not shown in FIGS. 1 and 2, as shown in FIG. 3, a plurality of linear shapes spreading radially around the center of the opening 9 in the substrate inner layer 12 a (second layer) of the printed circuit board 7. A radial metal foil 2a ′ formed on the substrate inner layer 12c is formed.
The same radial metal foil 2b ′ is formed on the (fourth layer), and the gap between the radial metal foil 2a ′ of the substrate inner layer 12a (second layer) and the radial metal foil 2b ′ of the substrate inner layer 12c (fourth layer) is formed. These are electrically connected by plated through holes 2c ′ that penetrate the printed board in the thickness direction.

  Another winding 2 ′ different from the winding 2 is formed on the printed circuit board 7 by the radial metal foil 2a ′, the radial metal foil 2b ′, and the through hole 2c ′ formed in the inner layer of the substrate, A double winding is formed by the winding 2 and the winding 2 ′ formed on the printed circuit board 7.

  Further, on the substrate inner layer 12b (third layer) at the approximate center in the thickness direction of the printed circuit board 7, there are a circumferential metal foil 3a and a circumferential metal foil 3a ′ having the center of the opening 9 as the center. Is formed. The circumferential metal foil 3a and the circumferential metal foil 3a ′ are electrically connected so as to be a return line to the winding 2 and the winding 2 ′, and the winding 2, the winding 2 ′, the circle The circumferential metal foil 3a and the circumferential metal foil 3a ′ are electrically connected in series at a point Q.

  In FIG. 2, the radial metal foil 2a on the substrate surface 11a (first layer) is indicated by a solid line, and the radial metal foil 2b on the substrate back surface 11b (fifth layer) is indicated by a broken line. (The radial metal foils 2a 'and 2b' of the second layer and the fourth layer are not shown). Further, the circumferential metal foil 3a and the circumferential metal foil 3a 'are indicated by two-dot chain lines.

  Further, the area surrounded by the winding 2 composed of the radial metal foil 2a on the substrate surface 11a (first layer) and the radial metal foil 2b on the substrate back surface 11b (fifth layer), and the circumferential metal foil 3a as the return line The radius of the circumferential metal foil 3a in the substrate inner layer 12b (third layer) of the printed circuit board 7 is determined so that the surrounding area is equal. Further, the area surrounded by the winding 2 ′ composed of the radial metal foil 2a ′ of the substrate inner layer 12a (second layer) and the radial metal foil 2b ′ of the substrate inner layer 12c (fourth layer), and the circumferential metal as the return line The radius of the circumferential metal foil 3a ′ in the substrate inner layer 12b (third layer) of the printed circuit board 7 is determined so that the area surrounded by the foil 3a ′ is equal.

  In these printed circuit boards, the winding 2, the winding 2 ′, the circumferential metal foil 3 a, and the circumferential metal foil 3 a ′ are placed in sufficiently accurate positions by using a conventional general printed circuit board manufacturing technique. It is possible to produce.

FIG. 4 is an example of a specific external view of the printed circuit board 7 of the printed circuit board type Rogowski coil. The outer shape of the printed circuit board 7 is a regular octagon, and a mounting hole 10 is provided at each apex of the regular octagon.
According to the current transformer having the above-described configuration according to the first embodiment of the present invention, the following operations and effects can be obtained.

  That is, since it is possible to provide a Rogowski coil having a multi-winding structure in a printed circuit board type Rogowski coil in which windings are formed of metal foil formed on the printed circuit board, While achieving the same error performance, it is possible to obtain a secondary output voltage that is a multiple corresponding to the number of multiple turns with the same board size as a conventional printed board type Rogowski coil. Therefore, the conventional printed circuit board type Rogowski coil has excellent noise resistance.

  In addition, as shown in FIG. 18 or FIG. 19, when the conductor is bent, when the conductor exists outside the Rogowski coil, or when the conductor is arranged obliquely with respect to the Rogowski coil. As described above, an external magnetic field in a direction penetrating the central opening 9 of the printed circuit board 7 may exist due to the arrangement of the Rogowski coil. Even in such a case, by determining the radius of the circumferential metal foils 3a and 3a ′ so that the total area surrounded by the plurality of windings and the total area surrounded by the plurality of return lines are equal, The impact can be reduced.

Therefore, even when there is an external magnetic field in a direction penetrating the central opening 9 of the printed circuit board 7, the total area surrounded by the plurality of windings is equal to the total area surrounded by the plurality of return lines. The sum of the voltages generated in the plurality of windings and the sum of the voltages generated in the plurality of return lines are substantially the same in magnitude and reversed in polarity because the magnetic flux generated by
For this reason, it is possible to prevent the current measurement from being affected by the external magnetic field, and to realize a highly accurate current measurement.

  Also, with the printed circuit board type Rogowski coil, it is possible to easily manufacture multiple windings and return lines in the correct position using general printed circuit board manufacturing technology. Can be produced.

  In particular, when the number of multiple windings is relatively small, such as a double winding or triple winding structure, there are only two or three circumferential metal foils as return paths, so a plurality of circumferential metal foils. Are all arranged on the same substrate inner layer, the number of layers of the substrate can be reduced, and a printed circuit board can be manufactured at a lower cost.

  In addition, by making the outer shape of the printed circuit board 7 into a regular octagon, the outer shape of the printed circuit board 7 can be machined in a linear shape with a low processing cost, and at the same time, the installation space for the Rogowski coil can be reduced with respect to a square shape or the like. Can do. In particular, compared to a case where the outer shape, which is expensive to process the printed circuit board, is circular, a regular octagon can provide a similar mounting space.

  In the present embodiment, the case where a double winding is formed as a coil on a printed circuit board having a five-layer configuration has been described as an example. However, when a triple winding is formed as a coil on a printed circuit board having a seven-layer configuration, Further, multiple windings such as a five-fold winding, a six-fold winding, etc. can be formed. In this case, the same effect as the first embodiment can be obtained.

  In the first embodiment, the circumferential metal foils 3a and 3a ', which are return lines, are all formed on the substrate inner layer 12b (third layer). On the other hand, the printed circuit board 7 may have a six-layer structure, and the circumferential metal foil 3a may be formed on the third layer, and the circumferential metal foil 3a 'may be formed on the fourth layer. In this case, the radial metal foils formed on the fourth layer and the fifth layer in the first embodiment are formed on the fifth layer and the sixth layer, respectively.

  In addition, although the modification of 1st Embodiment was mentioned as an example here, in the case of a more multiple winding structure, for example, in the case of a triple winding structure, there are three circumferential metal foils. These may be formed individually on the three layers of the substrate. Alternatively, two may be formed on the same inner layer, and the other may be formed on another inner layer. The same applies to the case of a more multiple winding structure.

  Even in such a modified example, the same effect as the first embodiment can be obtained, and when the number of multiple windings is relatively large, the circumferential metal foil serving as the return line is divided into several inner layers. This has the advantage that the area surrounding the return line can be easily adjusted. However, it goes without saying that it is desirable to reduce the number of inner layers constituting the return route as much as possible from the viewpoint of cost reduction.

  Next, a second embodiment of the present invention will be described with reference to the drawings. 5, 6 and 7 are diagrams showing the configuration of the Rogowski coil of the current transformer according to the second embodiment of the present invention. In this embodiment, a case will be described in which a quadruple winding is formed as a winding on a printed circuit board having an eight-layer structure.

  In FIG. 5, the printed circuit board 7 has an eight-layer structure comprising a substrate surface 11a, a substrate back surface 11b, and six substrate inner layers 12a, 12b, 12c, 12d, 12e, and 12f sandwiched between the substrate surface 11a and the substrate back surface 11b. It is a printed circuit board of composition. The printed circuit board 7 has a circular opening 9 at the center through which a conductor through which a main circuit alternating current flows is passed.

FIG. 6 is an external view of the printed circuit board 7 shown in FIG. 5 as viewed from the central axis direction of the opening 9.
FIG. 7 is a schematic cross-sectional view of the printed circuit board 7 shown in FIG. 5 cut along the line VII-VII and viewed in the direction of the arrow.

  The Rogowski coil 1 of the current transformer according to the present embodiment is a radial metal formed in a plurality of linear shapes radially extending from the substrate surface 11a (first layer) of the printed circuit board 7 about the center of the opening 9 as a center. The foil 2a-1 is formed, the same radial metal foil 2b-1 is formed on the substrate inner layer 12a (second layer), and the radial metal foil 2a-1 and the substrate inner layer 12a (first layer) on the substrate surface 11a (first layer) are formed. The two-layer radial metal foil 2b-1 is electrically connected by a plated through hole 2c-1 that penetrates the printed board in the thickness direction.

One winding 2-1 is formed on the printed circuit board 7 by the radial metal foil 2a-1, the radial metal foil 2b-1, and the through hole 2c-1.
Although not shown in FIGS. 5 and 6, as shown in FIG. 7, as shown in FIG. 7, a plurality of linear shapes spreading radially around the center of the opening 9 in the inner layer 12 b (third layer) of the printed circuit board 7. The same radial metal foil 2b-2 is formed on the substrate inner layer 12c (fourth layer), and the radial metal foil 2a-2 of the substrate inner layer 12b (third layer) is formed. And the radial metal foil 2b-2 of the substrate inner layer 12c (fourth layer) are electrically connected by a plated through hole 2c-2 that penetrates the printed board in the thickness direction.

  A second winding different from the first winding 2-1 is formed on the printed circuit board 7 by the radial metal foil 2a-2, the radial metal foil 2b-2, and the through hole 2c-2 formed in the inner layer of the substrate. A line 2-2 is formed.

  Similarly, a third winding 2-3 and a fourth winding 2-4 are formed on the printed circuit board 7 in the same manner as the first winding 2-1, the second winding 2-2. A quadruple winding is formed on the printed circuit board 7.

In FIG. 6, the radial metal foil 2a-1 on the substrate surface 11a (first layer) is indicated by a solid line, and the radial metal foil 2b-1 on the substrate inner layer 12a (second layer) is indicated by a broken line. (Radial metal foils 2a-2 to 2b-4 of the third to eighth layers are not shown)
Here, the winding 2-1 and the winding 2-3 are wound around the central axis of the opening 9 in FIG. On the other hand, the windings 2-2 and 2-4 are wound around the central axis of the opening 9 in FIG. The winding 2-1, the winding 2-2, the winding 2-3, and the winding 2-4 are electrically connected in series.

Further, the shape of each winding is determined so that the total area surrounded by the windings 2-1 and 2-3 is equal to the total area surrounded by the windings 2-2 and 2-4. Yes.
According to the current transformer having the above-described configuration according to the second embodiment of the present invention, the following operations and effects can be obtained.

  That is, since it is possible to provide a Rogowski coil having a multi-winding structure in a printed circuit board type Rogowski coil in which windings are formed of metal foil formed on the printed circuit board, A secondary output voltage that is a multiple corresponding to the number of multiple turns can be obtained with the same board size as a conventional printed circuit board type Rogowski coil while achieving the same error performance. Therefore, the conventional printed circuit board type Rogowski coil has excellent noise resistance.

  Further, in the Rogowski coil of the current transformer in the present embodiment, the windings 2-1 and 2-3 wound on one direction (clockwise) formed on the printed circuit board 7 are the conventional ones shown in FIG. The windings 2-2 and 2-4 wound in the opposite direction (counterclockwise direction) correspond to the conventional return path 3. In order to reduce the influence of the external magnetic field, the total area surrounded by multiple windings wound in one direction and the total area surrounded by multiple windings wound in the opposite direction are almost equal. It is only necessary to design, and it is possible to easily manufacture an accurate winding by using a general printed circuit board technology.

  Therefore, even when there is an external magnetic field that penetrates through the central opening 9 of the printed circuit board 7, the magnetic flux Φ interlinked by the external magnetic field is substantially common to a plurality of windings wound in opposite directions. Therefore, the voltage generated in each of the plurality of windings wound in opposite directions by the magnetic flux Φ is canceled out, so that the current measurement is prevented from being affected by the external magnetic field, and high-accuracy current measurement can be realized. .

  In the present embodiment, the case where a quadruple winding is formed as a winding on an eight-layer printed circuit board has been described as an example. However, only the even number) can be configured, and in this case, the same effect as that of the second embodiment can be obtained.

  In the present embodiment, the winding in the clockwise direction and the winding in the counterclockwise direction are alternately formed with respect to the quadruple winding, but the first and second windings are Similar effects can be obtained even when the third and fourth windings are wound counterclockwise and wound counterclockwise.

  Further, of the (2 × N) windings, N windings are wound clockwise, and the remaining N windings are stacked in any order as long as the remaining N windings are wound counterclockwise. However, similar effects can be obtained.

  Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 8 is a diagram showing a configuration of a Rogowski coil of a current transformer according to the third embodiment of the present invention.

  In this embodiment, a case will be described in which a quadruple winding is formed as a winding on a printed circuit board having an eight-layer structure.

  In FIG. 8, the printed circuit board 7 includes a substrate surface 11a, a substrate back surface 11b, and six substrate inner layers 12a, 12b, 12c, 12d, 12e, and 12f sandwiched between the substrate surface 11a and the substrate back surface 11b. This is a printed circuit board having an eight-layer structure. The printed circuit board 7 has a circular opening 9 at the center through which a conductor through which a main circuit alternating current flows is passed.

As shown in the figure, a plurality of linear metal foils 2a-1 are formed on the substrate surface 11a (first layer) of the printed circuit board 7 so as to extend radially about the center of the opening 9, and the substrate inner layer 12c. The same radial metal foil 2b-1 is formed on the (fourth layer), and the radial metal foil 2a-1 on the substrate surface 11a (first layer) and the radial metal foil 2b-1 on the substrate inner layer 12c (fourth layer) Are electrically connected by plated through holes 2c-1 penetrating the printed board in the thickness direction.
A first winding 2-1 wound around the printed circuit board 7 in the clockwise direction is formed by the radial metal foil 2a-1, the radial metal foil 2b-1, and the through hole 2c-1.

  Similarly, a plurality of radial metal foils 2a-2 are formed on the substrate inner layer 12a (second layer) of the printed circuit board 7 and are formed in a plurality of linear shapes extending radially about the center of the opening 9, and the substrate inner layer 12b ( The same radial metal foil 2b-2 is formed on the third layer), and the radial metal foil 2a-2 of the substrate inner layer 12a (second layer) and the radial metal foil 2b-2 of the substrate inner layer 12b (third layer) are formed. The space is electrically connected by a plated through hole 2c-2 that penetrates the printed board in the thickness direction. By the radial metal foil 2a-2, the radial metal foil 2b-2, and the through hole 2c-2 formed in the inner layer of the substrate, a second winding 2-2 wound clockwise around the printed circuit board 7 is formed. Has been.

The windings 2-1 and 2-2 wound in the clockwise direction are electrically connected in series to form a set of double windings 2X-1.
A third winding 2-3 and a fourth winding 2-4 wound in a counterclockwise direction are formed on the printed circuit board 7 with the same configuration, and the winding 2-3 and the winding 2-4 are formed. Are electrically connected in series to form another set of double windings 2X-2.
Here, the first set of double windings 2X-1 and the other set of double windings 2X-2 constitute the windings so that they are mirror images of each other.

Two double windings 2X-1 and 2X-2 that are mirror images of each other are electrically connected in series.
According to the current transformer according to the third embodiment of the present invention having the above configuration, the following effects are obtained in addition to the operational effects of the current transformer according to the second embodiment.

  That is, a set of multiple windings 2X-1 wound in one direction (clockwise) formed on the printed circuit board 7 corresponds to the winding 2 of the conventional Rogowski coil shown in FIG. Another set of multiple windings 2X-2 wound in the direction (counterclockwise) corresponds to the conventional return line 3. In the present invention, one set of multiple windings 2X-1 wound in one direction (clockwise) and another set of multiple windings 2X-2 wound in the opposite direction (counterclockwise) are mutually connected. Because of the mirror image relationship, the area surrounded by the two multiple windings 2X-1 and 2X-2 can be made very accurately equal. Therefore, even in the presence of an external magnetic field that penetrates through the central opening 9 of the printed circuit board 7, the magnetic flux Φ interlinking the two multiple windings by the external magnetic field is common, and therefore, two windings are generated by the magnetic flux Φ. Since the voltage generated in each of the lines is canceled out, it is possible to prevent current measurement from being affected by an external magnetic field, and to realize highly accurate current measurement.

  In the present embodiment, the case where a quadruple winding is formed as a winding on an eight-layer printed circuit board has been described as an example. However, only an even number) can be configured, and in this case, the same effect can be obtained.

  Next, a fourth embodiment of the present invention will be described with reference to the drawings. The fourth embodiment is an example in which the configuration of the Rogowski coil 1 according to the second embodiment is modified, and will be described with reference to a schematic cross-sectional view of a printed board shown in FIG.

In the present embodiment, a case will be described in which a triple winding is formed as a winding on a printed circuit board having a seven-layer structure.
In FIG. 9, the printed circuit board 7 has a seven-layer structure comprising a substrate surface 11a, a substrate back surface 11b, and five substrate inner layers 12a, 12b, 12c, 12d and 12e sandwiched between the substrate surface 11a and the substrate back surface 11b. It is a printed circuit board. The printed circuit board 7 has a circular opening 9 at the center through which a conductor through which a main circuit alternating current flows is passed.

As shown in the figure, the Rogowski coil 1 has radial metal foils 2a-1 formed in a plurality of linear shapes radially extending from the surface substrate 11a (first layer) of the printed circuit board 7 about the center of the opening 9 as a center. The same radial metal foil 2b-1 is formed on the substrate inner layer 12a (second layer), and the radial metal foil 2a-1 of the front substrate 11a (first layer) and the radial of the substrate inner layer 12a (second layer) are formed. The metal foil 2b-1 is electrically connected by a plated through hole 2c-1 penetrating the printed board in the thickness direction.
A first winding 2-1 is formed on the printed circuit board 7 by the radial metal foil 2a-1, the radial metal foil 2b-1, and the through hole 2c-1.

  Similarly, a second winding 2-2 is formed between the substrate inner layer 12b (third layer) and the substrate inner layer 12c (fourth layer) of the printed circuit board 7, and the substrate inner layer 12e (sixth layer) and the back substrate 11b. A third winding 2-3 is formed between the (seventh layer).

Thus, a triple winding is formed on the printed circuit board 7 by the winding 2-1, the winding 2-2, and the winding 2-3.
In addition, a circumferential metal foil 3 a having the center of the opening 9 as a center is formed in the substrate inner layer 12 d at a substantially center in the thickness direction of the printed board 7.

Here, the winding 2-1 is wound around the printed board 7 in the clockwise direction in the figure, and the winding 2-3 is wound in the counterclockwise direction in the figure.
Winding 2-3 is formed to act as a return line for winding 2-1. That is, the winding is formed so that the area surrounded by the winding 2-1 is equal to the area surrounded by the winding 2-3.

  On the other hand, the circumferential metal foil 3a is formed to be a return line for the winding 2-2. That is, the radius of the circumferential metal foil 3a in the substrate inner layer 12d of the printed circuit board 7 is determined so that the area surrounded by the winding 2-2 is equal to the area surrounded by the circumferential metal foil 3a that is the return line. ing.

The thus formed winding 2-1, winding 2-2, circumferential metal foil 3 a and winding 2-3 are electrically connected in series.
In the current transformer according to the fourth embodiment having the above-described configuration, the following effects are obtained in addition to the operational effects of the current transformer according to the second embodiment.

  That is, the application of the second embodiment of the present invention is limited to the case where the number of multiple windings is an even number, but the present embodiment is limited to the case where the number of multiple windings is an odd number. It can be implemented. When the number of multiple windings is an odd number, that is, (2 × N + 1), the concept of the second embodiment is applied to 2 × N windings 2-1 and 2-3 wound in opposite directions. Thus, errors due to an external magnetic field can be reduced. For the remaining one winding 2-2, the error caused by the external magnetic field can be reduced by adjusting the area surrounded by the circumferential metal foil 3a corresponding to the return line by applying the concept of the first embodiment. it can.

  Therefore, even when there is an external magnetic field that penetrates through the central opening 9 of the printed circuit board 7, it is possible to prevent the external magnetic field from being affected by the current measurement, and to realize highly accurate current measurement.

  In this embodiment, a case where a triple winding is formed as a winding on a printed circuit board having a seven-layer structure has been described as an example. However, a multiple winding (9 windings, 11 windings,... However, the same effect can be obtained even when only odd numbers are configured.

  Next, a fifth embodiment of the present invention will be described with reference to the drawings. The fifth embodiment is an example in which the configuration of the Rogowski coil 1 according to the first to fourth embodiments is modified. Therefore, the configuration of the printed circuit board 7 to be applied is the same as the configuration of the printed circuit board in any one of the first to fourth embodiments, and thus the description thereof is omitted.

In FIG. 10, the Rogowski coil 1 is provided with a plurality of printed circuit boards 7 in any of the first to fourth embodiments described above, and the central axis of the opening 9 at the center of each printed circuit board 7 is It is fixed in close contact to match. Each printed circuit board 7 is configured to be electrically connected in series.
In the current transformer according to the fifth embodiment having such a configuration, the following effects can be obtained in addition to the operational effects of the current transformers of the first to fourth embodiments.

  That is, the output of each printed circuit board 7 is added as the output voltage of the Rogowski coil 1, and the output voltage per unit current and unit frequency appears doubled by the number of printed circuit boards 7.

  Therefore, according to the present embodiment, in the state where the relationship that the area surrounded by the winding is equal to the area surrounded by the return line is maintained, the output current per unit current and unit frequency, that is, the sensitivity of the Rogowski coil 1 is set. Can be adjusted. Therefore, it is possible to easily obtain an output voltage at a level suitable for processing in the sensor unit described later while preventing the external magnetic field from being affected by the current measurement.

Next, a sixth embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a system configuration diagram of a current transformer according to the present invention. In the figure, the current transformer is composed of a Rogowski coil 1 through which a conductor 5 is attached, a sensor unit (SU) 20 disposed in the vicinity of the Rogowski coil 1, and an optical transmission means 30.
The Rogowski coil 1 and the sensor unit 20 are connected by a twisted pair electric wire 31.

  Since the configuration of the Rogowski coil 1 is the same as that of the Rogowski coil to which the configuration of the printed circuit board 7 of any of the first to fifth embodiments is applied, description thereof is omitted here.

  The sensor unit 20 cuts harmonics in order to reduce aliasing errors in an integration circuit 21 for analog signal processing of an analog voltage signal input from the Rogowski coil 1 via a twisted pair electric wire 31 and before the analog / digital conversion. A low-pass filter (LPF) 22 that turns off, an analog / digital converter 23 (hereinafter abbreviated as A / D converter) that converts an analog voltage signal into a digital electric signal, and a PLD (Programmable) that performs processing related to the digital electric signal A logic device) 24; a CPU (Central Processing Unit) 25; an electric / optical converter 26 (hereinafter abbreviated as an E / O converter) for converting a digital electric signal into a digital optical signal and outputting the digital optical signal; It consists of and.

  The power supply circuit 27 is supplied from a substation common power supply (not shown) or the like, and may be DC48V or DC220V. Generally, it is adjusted to the standard power supply of the substation, DC ± 5V, DC ± 3.3V, etc. A voltage necessary for the operation of the sensor unit 20 is generated. Although not shown, the sensor unit 20 may have a backup power source such as a battery.

  In the figure, the Rogowski coil connected to the sensor unit 20 is one channel, but the input is not necessarily one channel. For example, in the case of a three-phase batch type GIS, the U phase, V phase, W It is good also as a form which inputs the Rogowski coil output for three phases of phases into one sensor unit. In this case, the sensor unit 20 is configured such that an analog input circuit composed of an integrator and an LPF 22 forms a circuit for an input channel, and an A / D converter 23 is used as one to switch a multi-channel input by an analog multiplexer. The analog / digital conversion is performed.

  The configuration below the PLD 24 is the same as in the case of 1-channel input. In addition, between each input terminal of each Rogowski coil 1 and the sensor unit 20 is connected by the twisted pair electric wire 31 one by one.

  The optical transmission means 30 transmits the digital optical signal from the sensor unit 20 to a host system such as a protection control device. Although not shown, the optical transmission path 30 may be a one-to-one communication path, or may be configured to be connected by a LAN.

  According to the current transformer system having the above-described configuration according to the sixth embodiment of the present invention, in addition to the functions and effects of the current transformers of the first to fifth embodiments, the following functions and effects are provided. Is obtained.

The output voltage of the Rogowski coil 1 is an analog voltage signal proportional to the differential value of the main circuit alternating current flowing through the conductor 5 and is input to the sensor unit 20 via the twisted pair electric wire 31. The analog voltage signal input to the sensor unit 20 is integrated by the integrating circuit 21 to become an analog electric signal proportional to the main circuit alternating current. Next, harmonic components that cause aliasing errors are cut by the low-pass filter 21 and converted to digital electric signals by the A / D converter 23. Processing related to the digital electrical signal is performed by the PLD 24 and the CPU 25. The PLD 24 performs processing such as generation of an A / D converter timing signal (synchronization signal), generation of a control signal, and data transfer with the CPU 25. The CPU 25 converts the digital electric signal into a transmission format such as Manchester code, for example. At this time, a CRC code (Cyclic Redundaney Check) or an inverted duplex code can be added to the transmission format to improve transmission reliability. The digital electrical signal processed by the PLD 24 and the CPU 25 is converted into a digital optical signal by the E / O converter 26 and transmitted to the host system such as a protection control device via the optical transmission means 30.

  Since the Rogowski coil 1 in the current transformer of the present invention described in the first to fifth embodiments is composed of a printed circuit board, even if it adopts a multiple winding structure, its secondary output voltage. Is about several V / kA, and transmitting the secondary output voltage over a long distance is problematic in terms of noise resistance. However, in the present embodiment, since the sensor unit 20 that converts the secondary output voltage of the Rogowski coil 1 into a digital optical signal is arranged in the vicinity of the Rogowski coil 1 (printed circuit board 7), it is transmitted as an analog electric signal. The distance to be transmitted is 1 m or less at most, and the problem of signal quality degradation due to the influence of external noise can be avoided. In particular, since the Rogowski coil 1 and the sensor unit 20 are connected by a twisted pair electric wire 31, an external magnetic field received by the weak analog voltage output of the Rogowski coil 1 during transmission between the Rogowski coil 1 and the sensor unit 20. The influence of electromagnetic induction due to can be reduced.

  Since a digital optical signal is transmitted between the sensor unit 20 and the protection control device of the electric office main building, there is no signal deterioration due to the influence of noise even in long-distance transmission, and a high-quality alternating current amount is provided to the protection control device. it can.

  In addition, since the printed circuit board type Rogowski coil in the present invention adopts a multi-winding structure, the secondary output voltage of the Rogowski coil several times larger than the case where the conventional printed circuit board type Rogowski coil is used is used as the sensor unit. Can be entered. Therefore, it is easy to improve the S / N of the sensor unit, and it is possible to provide the protection control device with a higher quality AC current amount than before.

The CPU 25 may apply a digital filter to the digital electric signal representing the main circuit alternating current amount, or correct variations of the Rogowski coil 1 and analog circuits such as an integration circuit and a low-pass filter circuit (sensitivity correction, and The software may be configured to correct the phase. Further, the effective value of the main circuit current, which has been conventionally performed in a host system such as a BCU (Bay Control Unit), may be calculated and transmitted to the host system.
Further, although not shown, a temperature sensor may be provided in the sensor unit 20 and the temperature correction calculation may be performed by the CPU 25.

  In the configuration of the present invention, since the sensor unit 20 is disposed in the vicinity of the Rogowski coil 1, the temperature measured by the sensor unit 20 can be regarded as being substantially equal to the ambient temperature of the Rogowski coil 1, and fine temperature correction is possible. .

  Further, the following effects can be obtained as an incidental effect of the present invention. In other words, the input / output circuit between the main body of the transformation equipment that was previously mounted on the protection control device can be deleted, and all input / output is via communication, and there is no circuit that handles large voltage and large current. The hardware configuration of the control device can be configured only by a digital arithmetic processing unit for processing the protection control function and a communication unit for performing communication processing, and the hardware can be greatly reduced.

  Furthermore, since the current transformer of the present invention has a calculation function by the CPU, a part of the calculation conventionally performed by the protection control device can be substituted and the calculation load on the protection control device side can be reduced. it can. Furthermore, the protection control device uses the CPU free time generated by sharing a part of the calculation that the current transformer performed in the protection control device, so that the protection control device has more advanced protection control calculation and monitoring functions. Since it can be implemented, the performance of the entire protection control system can be improved.

  Next, a seventh embodiment of the present invention will be described with reference to the drawings. FIG. 12 is a system configuration diagram of a current transformer according to the seventh embodiment of the present invention. In the figure, the current transformer includes a Rogowski coil 1 attached with a conductor 5 passing therethrough, a sensor unit (SU) 20 disposed in the vicinity of the Rogowski coil 1, an optical transmission means 30, and a plurality of sensor units 20. It is comprised from the integrated unit (MU) 40 which integrates the digital optical signal transmitted from.

In the figure, the structure of the Rogowski coil 1 may be any of the Rogowski coils of the first to fifth embodiments, and the description thereof is omitted. Further, the configuration of the sensor unit (SU) 20 is the same as the configuration of FIG. 11 described in the sixth embodiment, and thus description thereof is omitted.
A configuration example of the integrated unit (MU) 40 will be described with reference to FIG. The sensor unit 20 and the integrated unit 40 are connected by an optical transmission means 32.

      The integrated unit 40 includes an optical / electrical converter 41 (hereinafter abbreviated as an O / E converter) that receives a digital optical signal from each sensor unit 20 and converts it into a second digital electrical signal, and a second digital signal. An integration unit 42 that integrates electrical signals to generate an electrical integrated transmission signal, a communication interface 46 with a host system, and a second electrical / optical converter 47 that converts the electrical integrated transmission signal into a second digital optical signal. (Hereinafter abbreviated as a second E / O converter) and a power supply circuit 49 and the like.

  The integration unit 42 includes a PLD 43, a CPU 44, a synchronization unit 45, and the like. The O / E converter 48 connected to the host system converts a synchronization signal transmitted as an optical signal from the host system into an electrical synchronization signal.

  The power supply circuit 49 is integrated from DC110V (DC48V, DC220V, etc., generally matched to the standard power supply of the substation) supplied from the substation common power supply 50, etc., DC ± 5V, DC ± 3.3V, etc. A voltage necessary for the operation of the unit 40 is generated. Although not shown, the integrated unit 40 may have a backup power source such as a battery.

A digital optical signal including information on the amount of alternating current from the sensor unit 20 connected to the integrated unit 40 is integrated into an integrated transmission signal in units of phases, integrated into an integrated transmission signal in units of lines, or in units of protection control. Various variations are conceivable, such as integration into an integrated transmission signal or integration into two or more integrated transmission signals in a protection control unit. Signal integration in the integration unit is not limited to integration into a certain type of integrated transmission signal, but an integrated transmission signal in the optimal format according to the layout of the substation, the system configuration of the protection control device, etc. To be integrated.
According to the current transformer system having the above-described configuration according to the seventh embodiment of the present invention, the following operational effects can be obtained.

Since the operational effects of the Rogowski coil 1 and the sensor unit 20 are the same as the operational effects described in the first to sixth embodiments, the description thereof is omitted.
The integrated unit 40 receives the digital optical signal from each sensor unit 20 by the O / E converter 41 and converts it into a second digital electric signal. The integrating means 42 integrates each second digital electric signal to generate an electric integrated transmission signal. The electrical integrated transmission signal is converted into a second digital optical signal by the communication interface 46 and the E / O converter 47 and transmitted to a host system such as a protection control device.

  Next, the operation of the integration unit 42 will be described in detail. The second digital electric signal converted by the O / E converter 41 is exchanged with the CPU 44 by the PLD 43. At this time, the PLD 43 checks the CRC code and the inverted duplex code added to the second digital electric signal, and detects a transmission error.

  The synchronization means 45 receives the time synchronization reference signal and the reference time data transmitted from the host system, and extracts and generates the sampling synchronization signal and the time stamp time data.

  The CPU 44 extracts the digital value of the AC current amount from the second digital electric signal received from each sensor unit 20, performs a synchronization complement calculation based on the sampling synchronization signal, and performs a synchronization complement calculation on the sampling synchronization deviation between the sensor units. Necessary information such as a time stamp and CRC code is added to the later alternating current digital value to generate an integrated transmission signal. Further, the CPU 44 performs abnormality monitoring of the sensor unit 20 and self-abnormality monitoring of the integrated unit 40, and transmits an alarm to the host system when an abnormality occurs. The abnormality monitoring of the sensor unit 20 includes, for example, power supply abnormality monitoring of the sensor unit 20, A / D converter accuracy monitoring, analog circuit monitoring, and the like.

FIG. 13 shows an example of a system configuration in which a plurality of alternating current amounts in a line unit as a protection control unit are transmitted as one integrated transmission signal. This figure is an example of a line 101 of a single-phase switchgear having a single bus configuration 105, and is shown in a three-phase connection diagram. The Rogowski coils 1 are attached to both sides of the circuit breaker 102 through the conductors 5, and sensor units 20 are attached in the vicinity of the Rogowski coils 1. Each of the sensor units 20a1 to 20a3, 20b1 to 20b3 and the integrated unit 40 are connected by an optical transmission means 32. The integrated system 40 and the host system 104 such as a protection control device are connected by a second optical transmission means 103. The integration unit 40 integrates digital values (digital optical signals) of alternating current amounts transmitted from all the sensor units 20a1 to 20a3 and 20b1 to 20b3 of the line line 101 attached to both sides of the circuit breaker into an integrated transmission signal. And transmitted to the host system 104.

As described above, since the AC unit information can be transmitted in the protection control unit by the integrated unit 40 disposed in the vicinity of the substation main body at the site, the transmission means can be efficiently operated. Since the digital unit transmits light between the integrated unit 40 and the protection control device of the electric power station main building, there is no signal deterioration due to the influence of noise even in long-distance transmission, and a high-quality alternating current amount is provided to the protection control device. it can.
In addition, since a large amount of electrical cables connecting the substation equipment on site and the protection control device in the main building can be greatly reduced, the installation time and cost of equipment installation work can be reduced.

  In addition, the following effects can be obtained as incidental effects of the present invention. In other words, the input / output circuit between the main body of the transformation equipment that was previously mounted on the protection control device can be deleted, and all input / output is via communication, and there is no circuit that handles large voltage and large current. The hardware configuration of the control device can be configured only by a digital arithmetic processing unit for processing the protection control function and a communication unit for performing communication processing, and the hardware can be greatly reduced.

  Furthermore, since the current transformer of the present invention has a calculation function by the CPU, a part of the calculation conventionally performed by the protection control device can be substituted and the calculation load on the protection control device side can be reduced. it can. Furthermore, the protection control device uses the CPU free time generated by the current transformer to share a part of the calculation performed by the protection control device, so that the protection control device has a more advanced protection control calculation and monitoring function. As a result, it is possible to improve the performance of the entire protection control system.

  Note that the integration of the digital value of the alternating current amount into the integrated transmission signal is not necessarily limited to the integration into one integrated transmission signal as described above. An example in the case of integrating into two integrated transmission signals will be described below.

  In FIG. 13, the alternating current amount by the Rogowski coil 1a attached to the busbar 105 side of the circuit breaker 102 is used for protection calculation of a line protection relay (not shown). On the other hand, the alternating current amount by the Rogowski coil 1b attached to the power transmission line side (not shown) of the circuit breaker 102 is used for protection calculation of a bus protection relay (not shown). In the line protection relay, the AC current amount transmitted from the sensor units 20a1 to 20a3 is integrated into the first integrated transmission signal so that it is not necessary to determine the type of current amount transmitted on the protection relay side. Transmit to the line protection relay. On the other hand, in the bus protection relay, the AC current amount transmitted from the sensor units 20b1 to 20b3 is integrated into the second integrated transmission signal and transmitted to the bus protection relay.

  The method of generating an integrated transmission signal in such a format is a configuration in which each unit (line protection relay, bus protection relay, BCU, etc.) of the integration unit 40 and the host system 104 is connected with a one-to-one transmission path. It is effective when

  Next, a modification of the embodiment of the present invention will be described. In the description of the sixth embodiment, the various calculation functions of the CPU 25 of the sensor unit 20 have been described. Among these, various calculation functions (sensitivity correction, excluding calculations related to data transmission between the sensor unit 20 and the integrated unit 40). As for the phase correction or the like, some or all of the calculations may be performed by the CPU 44 of the integrated unit 40.

  It is obvious that the same operational effects as those of the seventh embodiment can be obtained in such a modification. In this case, the sensor unit 20 only needs to have a function of converting the analog voltage signal, which is the output of the Rogowski coil 1, into a digital optical signal and transmitting the data to the integrated unit 40 via the optical transmission means 30. The CPU 25 of the unit 20 can be deleted. Therefore, the configuration of the sensor unit 20 is a very simple hardware configuration.

  The fact that the CPU 25 of the sensor unit 20 is unnecessary means that a control LSI equivalent to a high-precision CPU is unnecessary, and the minimum control means necessary for realizing the control and optical transmission means necessary for analog / digital conversion. Implementation of is necessary. With regard to this point, for example, control by the PLD 24 or such control can be realized by combining a general-purpose logic IC to realize the control.

  Furthermore, another modification of the present embodiment will be described. In the seventh embodiment, the sampling timing of analog / digital conversion of the analog voltage signal performed by the sensor unit 20 is asynchronous between the sensor units 20, and the sampling synchronization signal transmitted from the host system by the CPU 44 of the integrated unit 40 is used. Based on this, it is configured to perform synchronous interpolation calculation. On the other hand, a sampling synchronization signal can be transmitted from the integrated unit 40 to the sensor unit 20, and the sensor unit 20 can be configured to perform analog / digital conversion sampling based on the sampling synchronization signal. That is, the sampling timing in the sensor unit 20 can be synchronized with a time synchronization reference signal common to substations.

  In this case, the sampling synchronization signal is transmitted from the integrated unit 40 to the sensor unit 20 by optical transmission. Although not shown, an optical transmission means for sampling synchronization signal transmission is added to the sensor unit 20 and the integration unit 40 as hardware. In this case as well, it is obvious that the sensor unit 20 can have either a configuration having the CPU 25 or a configuration without the CPU 25. However, in either case, it is efficient to add the time stamp by the CPU 44 of the integrated unit 40. is there.

  In such a modified example, in addition to the same operational effects as those of the seventh embodiment, the following operational effects are obtained. According to this modification, the sampling timing of the analog voltage signal between the sensor units 20 that are normally arranged in plurality is synchronized with the time synchronization reference signal common to the substations. Therefore, the CPU 44 of the integrated unit 40 does not need to perform the sampling synchronization complement calculation, the load on the CPU 44 is lightened, and the software development burden is reduced.

  In this modification, the time synchronization reference signal common to the substation is transmitted to the sensor unit 20 via the integrated unit 40. However, the hardware configuration directly transmits the time synchronization reference signal common to the substation to the sensor unit 20. It is obvious that a similar effect can be obtained even if

  The present invention is not limited to the embodiment as described above. For example, one-to-one transmission between the integrated unit and each device of the host system (line protection relay, bus protection relay, BCU, etc.) Embodiments connected by roads are also included. According to such an embodiment, since the transmission information between the current transformer of the present invention and the host system can be simplified, the entire system can be simplified. In this case, it is often efficient to construct a plurality of integrated transmission signals generated in the integrated unit according to the transmission destination, such as a line protection relay and a bus protection relay.

  Further, an embodiment in which the integrated unit and each device of the host system (line protection relay, bus protection relay, BCU, etc.) are connected by a LAN (local area network) is also included. According to such an embodiment, since the transmission information between the current transformer of the present invention and the host system is transmitted on one LAN, one piece of information can be shared at each place, The configuration of the parts can also be standardized.

  Moreover, in order to improve the reliability of the current transformer system as a whole according to the present invention, the Rogowski coil, the sensor unit, and the integrated unit can be duplicated. Regarding the redundant configuration, various configurations such as a configuration in which all the components are completely duplicated to achieve mutual operation, a completely independent duplex configuration of each component, and a partial duplex configuration are conceivable. This is determined by the reliability and cost balance required by the system to which the current transformer of the present invention is applied, and is not limited to one redundant configuration.

  Further, the present invention relates to an electronic current transformer, but part of the invention can be applied in combination with an electronic instrument transformer. That is, when the instrument transformer to be adopted is an electronic instrument transformer and has a digitized output, or when the output of the electronic instrument transformer is an analog signal, or a conventional instrument Even when a transformer is used, when adding a unit for analog / digital conversion of the analog output, the digital output signal of the instrument transformer is also processed by the integrated unit described in the seventh embodiment. be able to. That is, the integrated unit can collectively transmit the main circuit AC electricity quantity (current and voltage information) detected by the current transformer and the instrument transformer to the host system in a protection control unit. In this case, the transmission means can be operated more efficiently, and the large number of electrical cables connecting between the on-site substation equipment and the protection control device in the main building can be further greatly reduced, reducing the installation time and cost of the equipment installation work. Needless to say, it can be further reduced.

The perspective view which shows the structure of the Rogowski coil in the 1st Embodiment of this invention. The front view which shows the structure of the printed circuit board in the 1st Embodiment of this invention. Sectional drawing which cut | disconnected FIG. 1 along the III-III line and looked at the arrow direction. FIG. 3 is an outline view showing a specific example of a printed circuit board according to the first embodiment of the present invention. The perspective view which shows the structure of the Rogowski coil in the 2nd Embodiment of this invention. The front view which shows the structure of the printed circuit board in the 2nd Embodiment of this invention. Sectional drawing which cut | disconnected FIG. 5 along the VII-VII line and looked at the arrow direction. Sectional drawing which shows the structure of the printed circuit board in the 3rd Embodiment of this invention. Sectional drawing which shows the structure of the printed circuit board in the 4th Embodiment of this invention. The perspective view which shows the structure of the Rogowski coil in the 5th Embodiment of this invention. The block diagram which shows the structure of the current transformer system by the 6th Embodiment of this invention. The block diagram which shows the structure of the current transformer system by the 7th Embodiment of this invention. The block diagram which shows the system structural example in the case of transmitting the some alternating current amount of the line unit in the 7th Embodiment of this invention as one integrated transmission signal. The front view which shows the structure of the conventional common Rogowski coil. The front view which shows the structural example of the other conventional Rogowski coil. FIG. 15 is a schematic diagram for explaining a state in which an external magnetic field is linked to a winding in the Rogowski coil shown in FIG. 14. FIG. 15 is a schematic diagram for explaining a state in which an external magnetic field is linked to a return line in the Rogowski coil shown in FIG. 14. The perspective view explaining an example of the factor which an external magnetic field generates. The perspective view explaining the other example of the factor which an external magnetic field generate | occur | produces.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rogowski coil, 2-1 to 2-4 ... Winding, 2X-1, 2X-2 ... Multiple winding, 2a, 2b ... Radial metal foil, 2c ... Through hole, 3 ... Return line, 3a ... Circle Peripheral metal foil, 4 ... terminal, 5 ... conductor, 6 ... core, 7 ... printed circuit board, 9 ... opening, 11a ... substrate surface, 11b ... substrate back surface, 12a-12f ... substrate inner layer, 20 ... sensor unit, DESCRIPTION OF SYMBOLS 21 ... Integrator, 22 ... Low pass filter, 23 ... Analog / digital converter, 24 ... PLD, 25 ... CPU, 26 ... Electric / optical converter, 27 ... Power supply circuit, 30, 32 ... Optical transmission means, 31 ... Twisted pair Electric wire, 40 ... integrated unit, 41 ... optical / electrical converter, 42 ... integrating means, 43 ... PLD, 44 ... CPU, 45 ... synchronizing means, 46 ... communication interface, 47 ... second electric / optical converter, 48 ... light / air converter, 49 ... power supply circuit 50 ... substation common power, 101 ... line circuit, 102 ... breaker, 103 ... second optical transmission means, 104 ... host system 105 ... single busbar.

Claims (2)

  A printed circuit board having a multilayer structure having an opening through which a conductor passes in the center, a substrate surface, a substrate back surface, and a plurality of substrate inner layers sandwiched between the substrate surface and the substrate back surface, A layer formed by a plurality of metal foils each having a metal foil radially arranged on the back surface of the substrate and the inner layer of the substrate, the center being the center of the opening, and the metal foil being substantially centered on the center of the opening A layer formed by a circumferential metal foil, and among the layers having the plurality of radial metal foils, the plating in which the radial metal foil between any two layers penetrates the printed board in the thickness direction Are electrically connected by the holes formed to form one winding, (2 × N + 1) windings formed in this way, and among the windings configured on the printed circuit board, (N + 1) windings and the remaining N windings Winding in opposite directions, electrically connecting the (2 × N + 1) windings and the circumferential metal foil in series, and setting the winding direction of the circumferential metal foil to the remaining A current transformer having a Rogowski coil in the same direction as the N windings and using this as a return line. Winding wound in one direction, winding wound in the opposite direction and circumferential metal foil are alternately laminated, and the alternately wound winding and circumferential winding The current transformer according to claim 1, wherein the metal foil is electrically connected in series.

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