Transformer device and power receiving and distribution facility

Abstract

To suitably enable a cancellation of an odd harmonic component.SOLUTION: A transformer device includes: an R-phase main winding, an S-phase main winding, and a T-phase main winding that are main windings wound around an R-phase core, an S-phase core, and a T-phase core respectively corresponding to a U-phase core, a V-phase core, and a W-phase core that output to a secondary side of a three-phase AC input to a primary side; and an R-phase branch winding, an S-phase branch winding, and a T-phase branch winding that are branch windings wound around the R-phase core, the S-phase core, and the T-phase core and having a number corresponding to the number of harmonics to be removed. In a pair determined by dividing a voltage output from each main winding and a voltage output from each branch winding into two, a pair phase difference, which is a phase difference between voltages included in the pair, is a value corresponding to the order of harmonics to be removed, and among voltages to be output, the voltages having a phase difference of approximately 120[°] are supplied to the same system, and in each pair, two voltages included in the pair are supplied to different systems.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a transformer device and a power receiving and distribution facility. [Background technology]

[0002] Generally, consumers who receive high voltage electricity have implemented measures and conducted extensive research to reduce the amount of harmonic current flowing out in order to prevent adverse effects on equipment and accidents caused by harmonics. For example, Patent Document 1 discloses a technology for removing odd harmonic components by using star-connected and delta-connected polyphase windings on the primary side of a transformer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-55718 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technology described in Patent Document 1 had difficulty completely removing the fifth and seventh harmonic components, which are often found among odd harmonic components. If the harmonic components could not be sufficiently removed and the outflowing harmonic current exceeded the standard set by the guidelines, it became necessary to consider additional countermeasures or install new, expensive countermeasure equipment such as an active filter. Therefore, there was a demand for a low-cost method for sufficiently removing odd harmonic components.

[0005] The present invention has been made in view of the above-mentioned points, and has as its object to provide a technique capable of suitably removing odd harmonic components. [Means for solving the problem]

[0006] One aspect of the present invention is a transformer device including an R-phase main winding, an S-phase main winding, and a T-phase main winding, which are main windings wound around an R-phase core, an S-phase core, and a T-phase core, respectively corresponding to a U-phase, a V-phase, and a W-phase that are output to a secondary side of a three-phase AC (not shown) input to a primary side, and R-phase branch windings, S-phase branch windings, and T-phase branch windings, which are wound around the R-phase core, the S-phase core, and the T-phase core, and the number of branch windings corresponds to the number of harmonics to be removed, wherein a voltage output from each of the main windings and a voltage output from each of the branch windings are divided into two pairs, and a pair phase difference, which is a phase difference between the voltages included in the pair, is a value corresponding to the order of the harmonic to be removed, and between the voltages output from each of the main windings and the voltages output from each of the branch windings, voltages with a phase difference of approximately 120° are supplied to the same system, and the two voltages included in each pair are supplied to different systems.

[0007] Furthermore, in a transformer device according to one embodiment of the present invention, when the pair phase difference is P, the order of the harmonic to be removed is A, and an arbitrarily determined positive odd number is K, the following formula is satisfied:

[0008]

number

[0009] In the transformer device according to an aspect of the present invention, when there are a plurality of harmonics to be removed, the pairing method differs for each of the harmonics to be removed.

[0010] In addition, in a transformer device according to one aspect of the present invention, when a first voltage is a reference voltage among the voltages output from each of the main windings and each of the branch windings, a second voltage is a voltage having a pair phase difference between the first voltage and the first voltage that corresponds to the order of a first harmonic that is one of a plurality of harmonics to be removed, a third voltage is a voltage that does not have a phase difference of approximately 120° from the first voltage or the second voltage but is one of the first voltage and the second voltage, and the third voltage and the fourth voltage are voltages having a pair phase difference of a value that corresponds to the order of the first harmonic, the first voltage and the third voltage, and the second voltage and the fourth voltage have a pair phase difference of a value that corresponds to the order of a second harmonic that is one of the plurality of harmonics to be removed but is one of the first harmonic, and the first voltage, the second voltage, the third voltage, and the fourth voltage are each supplied to different systems.

[0011] In addition, in a transformer device according to one aspect of the present invention, the branch windings are phase vectors that indicate the phase difference of the phase of the voltages output from the branch windings with respect to the neutral point of the main winding, and the end points of the phase vectors are located on circumscribed circles that pass through the end points of vectors that indicate the phase differences of the voltages output from the main windings in the R phase, S phase, and T phase with respect to the neutral point. By decomposing the phase vector into at least one of R phase, S phase, and T phase vectors, the branch positions on the winding from which the branch windings branch, the number of turns, and the phase of the core to be wound are determined.

[0012] In addition, in a transformer device according to one aspect of the present invention, the phase vector for the branch winding is resolved so that the number of turns from the position where the branch base winding branches out to the branch position of the branch winding on the branch base winding is equal to or greater than the number of turns of the branch winding.

[0013] In addition, in a transformer device according to one aspect of the present invention, the wire diameter of the branch winding is determined so that the allowable current value is larger by a predetermined percentage than the rated current value predetermined for the branch winding.

[0014] Another aspect of the present invention is a power receiving and distribution facility including the transformer device described above. [Effects of the Invention]

[0015] According to the present invention, odd harmonic components can be suitably removed. [Brief explanation of the drawings]

[0016] [Figure 1] 10A and 10B are diagrams for explaining a method for removing harmonic components of any order in the present embodiment. [Figure 2] FIG. 10 is a diagram for explaining how to form pairs when there is one harmonic to be removed and there are multiple pairs. [Figure 3] FIG. 3 is a diagram showing the waveforms of the first to fourth waves when the pairing shown in FIG. 2(A) is used. [Figure 4] FIG. 10 is a diagram for explaining how to form pairs when there are two harmonics to be removed and there are two pairs. [Figure 5] FIG. 5 is a diagram showing waveforms of the first to fourth waves of the fundamental wave, which are paired as shown in FIG. 4. [Figure 6] FIG. 5 is a diagram showing waveforms of first to fourth harmonics to be removed, in the pairing manner shown in FIG. 4. [Figure 7] 1 is a diagram illustrating an example of a basic configuration of a power receiving and distribution facility according to an embodiment of the present invention. [Figure 8] 3 is a diagram illustrating an example of the configuration of a secondary winding of the transformer device according to the present embodiment. FIG. [Figure 9] 4A and 4B are diagrams for explaining vectors of individual windings of a secondary winding of the transformer device according to the present embodiment. [Figure 10] 4A and 4B are diagrams for explaining the phase of the secondary side of the transformer device according to the present embodiment. [Figure 11] 3 is a diagram for explaining systems to which voltages output from each output terminal are supplied; FIG. [Figure 12]FIG. 1 is a first diagram for explaining a method for determining the branch positions, number of turns, and phase of the core to be wound for a winding having a desired phase. [Figure 13] FIG. 2 is a second diagram for explaining a method for determining the branch positions, number of turns, and phase of the core to be wound of a winding having a desired phase. [Figure 14] 10A and 10B are diagrams for explaining a specific method for determining the branch positions or the number of turns of a winding having a desired phase. [Figure 15] FIG. 10 is a diagram for explaining an example in which a phase difference changes due to a voltage drop. [Figure 16] 10 is a diagram for explaining the results of calculating high-voltage-converted harmonic current as a guideline standard for harmonic suppression measures for consumers receiving high voltage or extra-high voltage electricity. FIG. [Figure 17] 10 is a diagram for explaining an example of the configuration of a secondary winding of a transformer device according to Modification 1. FIG. [Figure 18] 10 is a diagram for explaining vectors of individual windings of a secondary winding of a transformer device according to Modification 1. FIG. [Figure 19] 10 is a diagram illustrating an example of the configuration of a secondary winding of a transformer device according to Modification 2. FIG. [Figure 20] 10 is a diagram for explaining the phases of the secondary sides of first to fourth transformers included in the transformer device according to Modification 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] [Embodiment] A preferred embodiment of a transformer device and a power receiving and distribution facility according to the present invention will be described in detail below with reference to the accompanying drawings. In the drawings, identical or similar parts are designated by identical or similar reference numerals. Note that the present invention is not limited to these embodiments and includes various modifications and improvements. In other words, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially identical, and the components described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components of the present invention may be made without departing from the spirit and scope of the present invention.

[0018] [Number of harmonics to be removed is 1] First, a method for removing one harmonic component of any order will be described with reference to FIGS.

[0019] FIG. 1 is a diagram illustrating a method for removing harmonic components of any order in this embodiment. FIG. 1(A) shows a first voltage and a second voltage having the same waveform as the first voltage but a different phase from the first voltage in a fundamental wave (first order). Hereinafter, the first voltage and the second voltage may be referred to as a first wave and a second wave. In FIG. 1(A), the phase difference between the first wave and the second wave is determined according to the order of the harmonic to be removed. Two voltages (first wave and second wave) having a phase difference according to the order of the harmonic to be removed are referred to as a pair. The phase difference between the two voltages included in the pair is referred to as a pair phase difference P. The pair phase difference P is calculated using the following equation (1): A is the order of the harmonic to be removed. K is an arbitrarily determined positive odd number.

[0020]

number

[0021] Specifically, we will explain the case of removing the fifth harmonic as an example. When removing the fifth harmonic, "5", which is the order of the fifth harmonic, is substituted for P. Furthermore, when "1" is substituted for K, the pair phase difference P becomes 360 ÷ (5 × 2) × 1 = 36°.

[0022] Figure 1(B) shows the first and second waves of the fifth harmonic. If the phase difference between the first and second waves of the fundamental wave (pair phase difference P) is 36°, then the phase difference between the first and second waves of the fifth harmonic, which is five times the frequency, is 180°. The first and second waves of the fifth harmonic, which are out of phase with each other, cancel each other out. By setting the phase difference between the first and second waves of the fundamental wave to P, the first and second waves of the fifth harmonic can be eliminated. If "3" is substituted for K in equation (1), the phase difference between the first and second waves of the fundamental wave becomes 108°, and the phase difference between the first and second waves of the fifth harmonic becomes 540°. Therefore, the first and second waves of the fifth harmonic are out of phase with each other and cancel each other out. Note that if an even number is substituted for K, the first and second waves of the harmonic to be removed will be in phase and reinforce each other. Therefore, an odd number should be substituted for K.

[0023] FIG. 2 is a diagram illustrating how to configure pairs when there is one harmonic to be removed and there are multiple pairs. FIG. 2 shows voltages with the same waveform but different phases, arranged in ascending order of phase difference from the first wave, with the first wave as the reference. FIG. 2(A) shows a first pair including the first and second waves, a second pair including the third and fourth pairs, and a third pair including the fifth and sixth waves. FIG. 2(A) shows an example in which the pair phase difference P between the first, second, and third pairs is set to 36° to remove the fifth harmonic. Here, because the first and second pairs have different voltages to be reversed, the phase difference between the first and second pairs (the phase difference between the first and third waves) can be any value other than 120°.

[0024] FIG. 2B shows an example of pairing different from that shown in FIG. 2A. FIG. 2A shows an example in which adjacent voltages are paired together, arranged in ascending order of their phase difference from the first wave. In contrast, FIG. 2B shows an example in which, arranged in ascending order of their phase difference from the first wave, a voltage is paired with the voltage two steps behind that voltage. In other words, in FIG. 2B, every other voltage is paired. Specifically, the first and third waves are paired as the first pair, and the second and fourth waves are paired as the second pair. Note that if the first and fourth waves were paired and the second and third waves were paired, the phase difference between the first and fourth waves would be greater than the phase difference between the second and third waves, and therefore the phase difference P between each pair would not be 36°. Any harmonic can be removed by forming regular pairs, such as pairing adjacent voltages or voltages every nth voltage (n is any natural number).

[0025] Figure 3 shows the waveforms of the first to fourth waves when the pairing arrangement shown in Figure 2(A) is used. Specifically, the first and second waves form the first pair, and the third and fourth waves form the second pair. In Figure 3, the harmonic order to be removed is assumed to be "5." Figure 3(A) shows the waveforms of the first to fourth waves of the fundamental wave. Because the harmonic order to be removed is "5," equation (1) derives the pair phase difference P as 36°. An example is shown in which the phase difference between the pair (the phase difference between the first and third waves) is 72°. Figure 3(B) shows the waveforms of the first to fourth waves of the fifth harmonic. In Figure 3(B), the first and second waves, and the third and fourth waves, are in opposite phase. Therefore, it can be seen that harmonics of any order can be removed even if the number of pairs is increased.

[0026] [Multiple harmonics to be removed] Next, a method for removing multiple harmonic components of any order will be described with reference to FIGS.

[0027] FIG. 4 is a diagram for explaining how to form pairs when there are two harmonics to be removed and there are two pairs. Similar to FIG. 2, FIG. 4 shows voltages with the same waveform but different phases, arranged in ascending order of phase difference from the first wave, with the first wave as the reference. The pair phase difference P(P1) of the pair at the fifth harmonic can be calculated as 36° by substituting "5" for A and "1" for K in Equation (1). The pair phase difference P(P2) of the pair at the seventh harmonic can be calculated as 77.15° by substituting "7" for A and "3" for K in Equation (1).

[0028] Because the pair phase difference P1 (36°) at the fifth harmonic is smaller than the pair phase difference P2 (77.15°) at the seventh harmonic, the first wave is paired with the adjacent second wave at the fifth harmonic, and the first wave is paired with the third wave, which is every other wave from the first wave, at the seventh harmonic. Specifically, at the fifth harmonic, the first and second waves are paired as the first pair, and the third and fourth waves are paired as the second pair, similar to the pairing shown in FIG. 2(A) (where adjacent voltages are paired). Also, at the seventh harmonic, the first and third waves are paired as the first pair, and the second and fourth waves are paired as the second pair, similar to the pairing shown in FIG. 2(B) (where every other voltage is paired).

[0029] FIG. 5 shows the waveforms of the first to fourth waves of the fundamental wave, paired as shown in FIG. 4. The first and second waves, and the third and fourth waves, each have a pair phase difference P1 (36°) at the fifth harmonic. The first and third waves, and the second and fourth waves, each have a pair phase difference P2 (77.15°) at the seventh harmonic. Therefore, the second and third waves have a phase difference of 77.15-36=41.15°.

[0030] Figure 6 shows the waveforms of the first to fourth waves of the harmonics to be removed, when paired as shown in Figure 4. Figure 6(A) shows the waveforms of the first to fourth waves of the fifth harmonic. In Figure 6(A), the voltages of the first pair (first and second waves) and the second pair (third and fourth waves) of the fifth harmonic are in opposite phase and cancel each other out. Therefore, the first to fourth waves of the fifth harmonic are removed.

[0031] Also, Figure 6(B) shows the waveforms of the first to fourth waves of the seventh harmonic. In Figure 6(B), the voltages contained in the first pair (first and third waves) and the second pair (second and fourth waves) of the seventh harmonic are in opposite phase and cancel each other out. Therefore, in the seventh harmonic, the first to fourth waves are removed. Therefore, even if the number of harmonics to be removed is increased, harmonics of any order can be removed.

[0032] In the above description, an example is shown in which four voltages, the first to fourth waves, are used to remove two harmonics of any order. However, this embodiment is not limited to this example, and the fifth to eighth waves may also be used. In this case, the phase difference between the first and fifth waves can be any value. That is, when removing two harmonics, the number of voltages is a multiple of four. Also, a third harmonic may be removed using the phase difference between the first and fifth waves. Another set of voltages (the fifth to eighth waves) can be used in addition to the set of first to fourth waves that removes the fifth and seventh harmonics, thereby removing another arbitrary harmonic. Specifically, an example of a pair for removing the fifth, seventh, and eleventh harmonics will be described. The pairs for the fifth harmonic are the first pair including the first and second waves, the second pair including the third and fourth waves, the third pair including the fifth and sixth waves, and the fourth pair including the seventh and eighth waves. The pairs for the seventh harmonic are the first pair including the first and third waves, the second pair including the second and fourth waves, the third pair including the fifth and seventh waves, and the fourth pair including the sixth and eighth waves. The pairs for the eleventh harmonic are the first pair including the first and fifth waves, the second pair including the second and sixth waves, the third pair including the third and seventh waves, and the fourth pair including the fourth and eighth waves. In this way, by using an additional set of voltages capable of removing any number of harmonics, the number of harmonics to be removed can be increased by one. Note that the number of voltages required doubles for each additional harmonic to be removed.

[0033] [Transformer device according to this embodiment] Next, with reference to FIGS. 7 to 11, a specific example of the configuration of a transformer device that removes the fifth harmonic and the seventh harmonic using the above-described method for removing harmonics will be described.

[0034] FIG. 7 is a diagram showing an example of the basic configuration of a power receiving and distribution equipment 1 according to this embodiment. The power receiving and distribution equipment 1 converts 6600 V high-voltage three-phase AC power received from a high-voltage three-phase power source 2 into power having a voltage and frequency that conforms to the specifications of a consumer's load equipment. The power receiving and distribution equipment 1 outputs the converted power divided into different systems, namely, a first system, a second system, a third system, and a fourth system. The power receiving and distribution equipment 1 includes a transformer device 3. The power receiving and distribution equipment 1 may be, for example, a cubicle in which a set of equipment that converts high-voltage power into power that conforms to the consumer's specifications is housed in a metal outer box. The power receiving and distribution equipment 1 may also be referred to as a power receiving and transforming equipment or a power receiving equipment. In addition to the transformer device 3, the power receiving and distribution equipment 1 includes various other equipment such as a power capacitor and a high-voltage load switchgear, but these are not shown in the figure. Although a transformer device that converts power received from a high-voltage three-phase power supply into low-voltage power has been given as an example, the present invention also includes a method of converting from a low-voltage three-phase power supply.

[0035] FIG. 8 is a diagram illustrating an example of the configuration of the secondary winding of the transformer device 3 according to this embodiment. The transformer device 3 includes a primary winding and a secondary winding as components. The primary winding includes an input winding. The secondary winding includes a main winding 10, a base winding 11, a first branch winding 21, a second branch winding 22, and a third branch winding 23. The main winding 10 has three winding portions (an R-phase main winding 10R, an S-phase main winding 10S, and a T-phase main winding 10T) corresponding to the input three-phase power (U-phase, V-phase, and W-phase). Like the main winding 10, the base winding 11, the first branch winding 21, the second branch winding 22, and the third branch winding 23 also have three winding portions. The U-phase, V-phase, and W-phase are input to the primary side (not shown). Furthermore, the R phase, S phase, and T phase are output to the secondary side.

[0036] The secondary side of the transformer device 3 has 12 output terminals: the R, S, and T terminals of the main winding 10, the R1, S1, and T1 terminals of the first branch winding 21, the R2, S2, and T2 terminals of the second branch winding 22, and the R3, S3, and T3 terminals of the third branch winding 23. The base winding 11 has an R01, S01, T01, R02, S02, and T02 terminals. The main winding 10 also has an R03, S03, and T03 terminal.

[0037] The input winding (not shown) may be either delta-connected or star-connected. High-voltage AC power is connected to the R-phase input terminal, S-phase input terminal, and T-phase input terminal of the input winding. A system of converting from a low-voltage three-phase power supply input may also be used. The main winding 10, base winding 11, first branch winding 21, second branch winding 22, and third branch winding 23 are each star-connected. However, the first branch winding 21, second branch winding 22, and third branch winding 23 are not completely star-connected.

[0038] The star-connected neutral points N of the main winding 10 and base winding 11 are connected to each other, and the base winding 11 is wound around the core so that its polarity is opposite to that of the main winding 10. The first branch winding 21 and the second branch winding 22 are formed by branching off from the base winding 11, and also serve as the neutral point N of the base winding 11. The third branch winding 23 is formed by branching off from the main winding 10, and also serves as the neutral point N of the main winding 10.

[0039] The R-phase base winding 11R branches off from the neutral point N, is wound around the R-phase core, and has terminals T01 and T02. The S-phase base winding 11S branches off from the neutral point N, is wound around the S-phase core, and has terminals R01 and R02. The T-phase base winding 11T branches off from the neutral point N, is wound around the T-phase core, and has terminals S01 and S02.

[0040] The R-phase first branch winding 21R branches off from the R01 terminal of the S-phase base winding 11S, is wound around the R-phase core, and has an R1 terminal. The S-phase first branch winding 21S branches off from the S01 terminal of the T-phase base winding 11T, is wound around the S-phase core, and has an S1 terminal. The T-phase first branch winding 21T branches off from the T01 terminal of the R-phase base winding 11R, is wound around the T-phase core, and has a T1 terminal.

[0041] The R-phase second branch winding 22R branches off from the S02 terminal of the T-phase base winding 11T, is wound around the R-phase core, and has an S2 terminal. The S-phase second branch winding 22S branches off from the T02 terminal of the R-phase base winding 11R, is wound around the S-phase core, and has a T2 terminal. The T-phase second branch winding 22T branches off from the R02 terminal of the S-phase base winding 11S, is wound around the T-phase core, and has an R2 terminal.

[0042] The R-phase third branch winding 23R branches off from the T03 terminal of the S-phase main winding 10S, is wound around the R-phase core, and has a T3 terminal. The S-phase third branch winding 23S branches off from the R03 terminal of the T-phase main winding 10T, is wound around the S-phase core, and has an R3 terminal. The T-phase third branch winding 23T branches off from the S03 terminal of the R-phase main winding 10R, is wound around the T-phase core, and has an S3 terminal.

[0043] FIG. 9 is a diagram illustrating the vectors of the individual windings of the secondary winding of the transformer device 3 according to this embodiment. FIG. 9 shows the phase of the power output from each winding with reference to the phase of the power output from the R-phase main winding 10R. As shown in the figure, the R-phase main winding 10R, S-phase main winding 10S, and T-phase main winding 10T, which are three-phase windings of the main winding 10, output voltages having a phase difference of 120° from the R-terminal, S-terminal, and T-terminal, respectively, similar to the input three-phase power. Furthermore, the R-phase main winding 10R, S-phase main winding 10S, and T-phase main winding 10T output voltages having a phase difference of 120° from the S03-terminal, T03-terminal, and R03-terminal to the T-phase third branch winding 23T, R-phase third branch winding 23R, and S-phase third branch winding 23S, respectively, similar to the input three-phase power.

[0044] The R-phase base winding 11R outputs a voltage having an opposite phase to the voltage output from the R terminal of the R-phase main winding 10R from the T01 terminal to the T-phase first branch winding 21T and from the T02 terminal to the S-phase second branch winding 22S. The S-phase base winding 11S outputs a voltage having an opposite phase to the voltage output from the S terminal of the S-phase main winding 10S from the R01 terminal to the R-phase first branch winding 21R and from the R02 terminal to the T-phase second branch winding 22T. The T-phase base winding 11T outputs a voltage having an opposite phase to the voltage output from the T terminal of the T-phase main winding 10T from the S01 terminal to the S-phase first branch winding 21S and from the S02 terminal to the R-phase second branch winding 22R.

[0045] The R1 terminal of the R-phase first branch winding 21R outputs a voltage in phase with the R terminal of the R-phase main winding 10R. The S1 terminal of the S-phase first branch winding 21S outputs a voltage in phase with the S terminal of the S-phase main winding 10S. The T1 terminal of the T-phase first branch winding 21T outputs a voltage in phase with the T terminal of the T-phase main winding 10T.

[0046] The S2 terminal of the R-phase second branch winding 22R outputs a voltage in phase with the R terminal of the R-phase main winding 10R. The T2 terminal of the S-phase second branch winding 22S outputs a voltage in phase with the S terminal of the S-phase main winding 10S. The R2 terminal of the T-phase second branch winding 22T outputs a voltage in phase with the T terminal of the T-phase main winding 10T.

[0047] The T3 terminal of the R-phase third branch winding 23R outputs a voltage that is opposite in phase to the R terminal of the R-phase main winding 10R. The R3 terminal of the S-phase third branch winding 23S outputs a voltage that is opposite in phase to the S terminal of the S-phase main winding 10S. The S3 terminal of the T-phase third branch winding 23T outputs a voltage that is opposite in phase to the T terminal of the T-phase main winding 10T.

[0048] 10 is a diagram illustrating the phase of the secondary side of the transformer device 3 according to this embodiment. The absolute value and phase of the voltage between the neutral point N, the R-phase main winding 10R, and the R terminal are equal to the absolute value and phase of the voltage between the neutral point N and the R1 terminal of the R-phase first branch winding 21R, and the phase lags by 36°. The absolute value and phase of the voltage between the neutral point N, the R-phase main winding 10R, and the R terminal are equal to the absolute value and phase of the voltage between the neutral point N and the R2 terminal of the T-phase second branch winding 22T, and the phase lags by 36+41.15=77.15°. The absolute value and phase of the voltage between the neutral point N, the R-phase main winding 10R, and the R terminal are equal to the absolute value and phase of the voltage between the neutral point N and the R3 terminal of the S-phase third branch winding 23S, and the ... phase lags by 36+41.15+36=113.15°.

[0049] If the voltage output from the R terminal is the first wave, the voltage output from the R1 terminal is the second wave, the voltage output from the R2 terminal is the third wave, and the voltage output from the R3 terminal is the fourth wave, then the first and second waves, and the third and fourth waves, respectively, have a phase difference of 36°. Furthermore, the first and third waves, and the second and fourth waves, respectively, have a phase difference of 77.15°. Therefore, the fifth and seventh harmonics can be eliminated by using the first to fourth waves. The phase of the voltage output from the S terminal of the S-phase main winding 10S or the T terminal of the T-phase main winding 10T as the reference is the same as the phase of the voltage output from the R terminal of the R-phase main winding 10R as the reference.

[0050] 11A and 11B are diagrams illustrating systems to which voltages output from each output terminal are supplied. Fig. 11A is a diagram illustrating voltages output from each output terminal of the transformer device 3 that are supplied to the first system. The voltages output from the R terminal of the R-phase main winding 10R, the S terminal of the S-phase main winding 10S, and the T terminal of the T-phase main winding 10T, each having a phase difference of 120°, are supplied to the first system. That is, the first system is supplied with three-phase power output from the main winding 10.

[0051] 11(B) is a diagram illustrating voltages supplied to the second system among the voltages output from the output terminals of the transformer device 3. The voltages output from the R1 terminal of the R-phase first branch winding 21R, the S1 terminal of the S-phase first branch winding 21S, and the T1 terminal of the T-phase first branch winding 21T, each having a phase difference of 120°, are supplied to the second system. That is, the three-phase power output from the first branch winding 21 is supplied to the second system.

[0052] 11(C) is a diagram illustrating voltages supplied to the third system among the voltages output from the output terminals of the transformer device 3. The voltages output from the S2 terminal of the R-phase second branch winding 22R, the T2 terminal of the S-phase second branch winding 22S, and the R2 terminal of the T-phase second branch winding 22T, each having a phase difference of 120°, are supplied to the third system. That is, the three-phase voltages output from the second branch winding 22 are supplied to the third system.

[0053] 11(D) is a diagram illustrating voltages supplied to the fourth system among the voltages output from the output terminals of the transformer device 3. The voltages output from the T3 terminal of the R-phase third branch winding 23R, the R3 terminal of the S-phase third branch winding 23S, and the S3 terminal of the T-phase third branch winding 23T, which have a phase difference of 120°, are supplied to the fourth system. That is, the four system is supplied with three-phase power output from the third branch winding 23.

[0054] In the transformer device 3 according to this embodiment, the voltages having a phase difference of approximately 120° are output to the same system. The voltages at the R terminal, R1 terminal, R2 terminal, and R3 terminal are output to different systems. The voltages at the S terminal, S1 terminal, S2 terminal, and S3 terminal are output to different systems. The voltages at the T terminal, T1 terminal, T2 terminal, and T3 terminal are output to different systems. This allows any harmonics to be removed.

[0055] FIG. 12 is a first diagram for explaining a method for determining the branch positions, number of turns, and phase of the core to be wound for a winding having a desired phase. FIG. 12 shows the voltage output from the S-phase main winding 10S, the voltage output from the T-phase main winding 10T, and the voltage of the desired phase, with the phase of the voltage output from the R-phase main winding 10R as the reference. In the following explanation, a vector indicating the phase of the output voltage relative to the neutral point N is referred to as a phase vector. In FIG. 12, the R-phase is the first phase, the S-phase is the second phase, and the T-phase is the third phase. In FIG. 12, the desired voltage has the same absolute value and a phase difference of 36° when the phase of the voltage output from the R-phase main winding 10R relative to the neutral point N is used as the reference. The tip (end point) of the phase vector (NY vector) of the desired voltage exists on a circumscribed circle that passes through the tips of the N-R vector indicating the phase of the R-phase main winding 10R (first phase) relative to the neutral point N, the NT vector indicating the phase of the T-phase main winding 10T (third phase), and the NS vector indicating the phase of the S-phase main winding 10S (second phase).

[0056] The branch position, number of turns, and core phase of the winding that outputs the desired voltage can be determined by decomposing the phase vector of the desired voltage into vectors for the R phase (first phase), S phase (second phase), and T phase (third phase). The phase vector of the desired voltage (NY vector) can be decomposed, for example, into an N-X1 vector, which is a first-phase vector, and an X1-Y vector, which is a second-phase vector. Since the X1-Y vector is a second-phase vector with its origin at X1, it branches off from a position on the first-phase main winding that corresponds to the magnitude of the N-X1 vector and is wound around the second-phase core (S-phase core) with a number of turns that corresponds to the magnitude of the X1-Y vector. The position that corresponds to the magnitude of the N-X1 vector is a position where "number of turns of the main winding: number of turns from the neutral point N to the branch position = magnitude of the NR vector: magnitude of the N-X1 vector." Furthermore, the number of turns according to the magnitude of the X1-Y vector is the number of turns that satisfies the following formula: "Number of turns of main winding: Number of turns of winding that outputs the voltage of the X1-Y vector = Magnitude of NR vector: Magnitude of the X1-Y vector." A winding that is formed by branching off from a winding and outputs a desired voltage is called a branch winding, and among the windings from which the branch windings branch off, a winding that is not a main winding may be called a base winding.

[0057] The above-described method of decomposing the phase vector is merely an example, and the phase vector may be decomposed into vectors other than those described above. The N-Y vector may be decomposed into, for example, a second-phase N-X2 vector and a first-phase X2-Y vector. Here, the X1-Y vector and the N-X2 vector, and the N-X1 vector and the X2-Y vector, are parallel to each other. Because the opposite sides are parallel to each other, a rectangle with vertices N, X1, Y, and X2 is a parallelogram. Because the opposite sides of a parallelogram have the same length, the X1-Y vector and the N-X2 vector, and the N-X1 vector and the X2-Y vector have the same magnitude. The winding that outputs the N-X2 vector voltage branches off from the neutral point N and is wound around the second-phase core with the same number of turns as the winding that outputs the X1-Y vector voltage. In addition, the winding that outputs the X2-Y vector voltage branches off from the tip (X2) of the winding that outputs the N-X2 vector voltage, and is wound around the first phase core with the same number of turns as the winding that outputs the N-X1 vector voltage.

[0058] FIG. 13 is a second diagram illustrating a method for determining the branch position, number of turns, and phase of the core to be wound for a winding having a desired phase. In FIG. 13, a desired first phase vector (N-Y1) and a desired second phase vector (N-Y2) are formed by branching from a common winding. Specifically, the N-Y1 vector can be decomposed into a second-phase N-X2 vector and a first-phase X2 vector. The N-Y2 vector can be decomposed into a second-phase N-X2 vector, a second-phase X2-X3 vector, and a third-phase X3-Y2 vector. When decomposed as described above, the N-Y1 vector and the N-Y2 vector share the second-phase N-X2 vector as a component. If the decomposed vectors are common, it is possible to share part of the winding without forming a winding for one of the vectors, which may reduce the number of turns of the entire transformer device 3.

[0059] FIG. 14 is a diagram for explaining a specific method for determining the branch position or number of turns of a winding having a desired phase. FIG. 14 shows, as an example, a case where the branch winding (X1-Y vector) branches off from the X1 position on the main winding. If the voltage between the R terminal of the R-phase main winding 10R and the S terminal of the S-phase main winding 10S is 200 V, the voltage between N-Y and N-R is 200 / √3 = 115.47 V. The voltage between X4 and Y is 115.47 × sin(36°) = 67.87 V. The voltage between X1 and Y is 67.87 × (2 / √3) = 78.38 V. From these results, (voltage between X1 and Y) / (voltage between N and R) = 78.38 / 115.47 = 67.9 [%], and the number of turns of the branch winding that outputs the voltage of the X1-Y vector is determined to be 67.9 [%] of the number of turns of the main winding.

[0060] Additionally, the voltage between X1 and X4 is 78.38 / 2 = 39.79 [V]. The voltage between N and X4 is 115.47 × cos(36°) = 93.42 [V]. The voltage between N and X1 is 93.42 - 39.19 = 54.23 [V]. From these results, (voltage between N and X1) / (voltage between N and R) = 54.23 / 115.47 = 47.0 [%], and the position where the branch winding that outputs the X1-Y vector voltage branches out is determined to be a position on the main winding that is 47.0 [%] from the neutral point N.

[0061] 12 to 14, it is possible to determine the number of turns of the winding that outputs the desired voltage, the branching position, and the phase of the core to be wound. Note that the above-mentioned determination method can be used in the same way even when one of the R phase, S phase, and T phase is set as the first phase, one of the remaining two phases is set as the second phase, and the remaining phase is set as the third phase.

[0062] Although the transformer device 3 supplies voltage to the first, second, third, and fourth systems, the power consumed by each system is not necessarily equal. Specifically, the number of devices, such as air conditioning equipment, operating on the first system may be smaller than the number of devices operating on the second system, resulting in an imbalance in the load on the system side. This imbalance in the load may result in a difference in the voltage drop across each winding, resulting in a phase difference that differs from the ideal value and potentially weakening the effectiveness of harmonic component removal. The branch windings have a smaller wire diameter (smaller capacitance) and larger conduction loss than the main winding, resulting in a greater impact of voltage drop. The transformer device 3 according to this embodiment reduces the impact of voltage drop by increasing the wire diameter of the branch windings. Specifically, the wire diameter of the branch windings is determined so that the allowable current value is a predetermined percentage greater than the rated current value predetermined for the branch windings. The predetermined percentage may be, for example, 20% or more. In other words, the wire diameter of the branch windings may be determined so that the allowable current is 1.2 times or more the rated current.

[0063] Furthermore, the influence of voltage drop may be reduced by decomposing the phase vector so that the number of turns of the branch winding is reduced. FIG. 15 is a diagram for explaining an example of how the phase difference changes due to voltage drop. FIG. 15 shows an example of decomposing a desired phase vector (N-R1) into an N-X1 vector and an X1-R1 vector. When the phase vector is decomposed as shown in FIG. 15, the N-X1 vector (branch winding) is larger than the X1-R1 vector (portion shared with the main winding). Because the branch winding has a smaller wire diameter (smaller electric capacity) than the main winding, the influence of voltage drop increases as the number of turns increases. In this embodiment, the phase vector for the branch winding is decomposed so that the number of turns from the branch position (e.g., neutral point N) of the branch base winding (main winding or base winding) of the branch winding to the branch position of the branch winding on the branch base winding is equal to or greater than the number of turns of the branch winding. That is, the vector of the branch winding is decomposed so as to be smaller than the vector from the neutral point N to the branch position on the branch base winding. The transformer device 3 according to the embodiment reduces the number of turns of the branch winding by decomposing the desired phase vector (N-R1) into an N-X2 vector and an X2-R1 vector.

[0064] FIG. 16 illustrates the results of calculating high-voltage-converted harmonic currents as the harmonic suppression guideline standard for consumers receiving high or extra-high voltage power. FIG. 16 shows the guideline compliance criteria and the harmonic current outflows at each order for the transformer device 3 according to the embodiment and a reactor-less six-pulse converter with a conversion coefficient K31 of 3.4 (hereinafter sometimes referred to as the comparison device). In FIG. 16, the calculations for the transformer device 3 are performed assuming that the maximum voltage is used in the first through fourth systems. The comparison device's harmonic current outflow exceeds the standard value for all orders, requiring additional measures or the addition of new equipment. In contrast, the transformer device 3 is able to reduce the outflow of the fifth and seventh harmonics, which are targeted for removal, to near 0 mA. Furthermore, the transformer device 3 is able to reduce the outflow of harmonics of orders 11 and above, which are not targeted for removal, compared to the comparison device. This reduces the cost of additional measures and investigations required to meet the guideline criteria.

[0065] The above-described transformer device 3 removes the fifth and seventh harmonics. However, this embodiment is not limited to this example, and harmonics of any order can be removed by adjusting the phase difference between the windings.

[0066] [Variation 1] Next, a transformer device 3A, which is a first modification of the transformer device 3, will be described in detail with reference to Figs. 17 and 18. In the transformer device 3 according to the embodiment, the first branch winding 21, the second branch winding 22, and the third branch winding 23 branch off from the main winding 10 or the base winding 11, and some windings of the main winding 10 or the base winding 11 are shared and used when outputting voltages of different phases. The transformer device 3A according to the first modification differs from the transformer device 3 in that it does not have any windings that are shared and used when outputting voltages of different phases. Note that in the following description, matters that have already been described may be omitted.

[0067] 17 is a diagram illustrating an example of the configuration of the secondary winding of the transformer device 3A according to Modification 1. The secondary winding of the transformer device 3A includes a main winding 10, a first base winding 31, a second base winding 32, a third base winding 33, a first branch winding 21, a second branch winding 22, and a third branch winding 23. The first base winding 31, the second base winding 32, and the third base winding 33 each have three winding portions.

[0068] The first base winding 31, the second base winding 32, and the third base winding 33 are each star-connected. The star-connected neutral points N of the main winding 10, the first base winding 31, the second base winding 32, and the third base winding 33 are connected to each other. The first base winding 31 and the second base winding 32 are wound around the core so that their polarities are opposite to those of the main winding 10. Furthermore, the third base winding 33 is wound around the core so that its polarity is the same as that of the main winding 10.

[0069] The R-phase first base winding 31R branches off from the neutral point N, is wound around the R-phase core, and has a T01 terminal. The S-phase first base winding 31S branches off from the neutral point N, is wound around the S-phase core, and has a R01 terminal. The T-phase first base winding 31T branches off from the neutral point N, is wound around the T-phase core, and has a S01 terminal.

[0070] The R-phase second base winding 32R branches off from the neutral point N, is wound around the R-phase core, and has a T02 terminal. The S-phase second base winding 32S branches off from the neutral point N, is wound around the S-phase core, and has a R02 terminal. The T-phase second base winding 32T branches off from the neutral point N, is wound around the T-phase core, and has a S02 terminal.

[0071] The R-phase third base winding 33R branches off from the neutral point N, is wound around the R-phase core, and has an S03 terminal. The S-phase third base winding 33S branches off from the neutral point N, is wound around the S-phase core, and has a T03 terminal. The T-phase third base winding 33T branches off from the neutral point N, is wound around the T-phase core, and has an R03 terminal.

[0072] Fig. 18 is a diagram for explaining vectors of the individual windings of the secondary winding of the transformer device 3A according to Modification 1. Fig. 18 shows the phase of the power output from each winding with reference to the phase of the power output from the R-phase main winding 10R.

[0073] The R-phase first base winding 31R outputs a voltage having an opposite phase to the voltage output from the R terminal of the R-phase main winding 10R from the T01 terminal to the T-phase first branch winding 21T. The S-phase first base winding 31S outputs a voltage having an opposite phase to the voltage output from the S terminal of the S-phase main winding 10S from the R01 terminal to the R-phase first branch winding 21R. The T-phase first base winding 31T outputs a voltage having an opposite phase to the voltage output from the T terminal of the T-phase main winding 10T from the S01 terminal to the S-phase first branch winding 21S.

[0074] The R-phase second base winding 32R outputs a voltage having an opposite phase to the voltage output from the R terminal of the R-phase main winding 10R from the T02 terminal to the S-phase second branch winding 22S. The S-phase second base winding 32S outputs a voltage having an opposite phase to the voltage output from the S terminal of the S-phase main winding 10S from the R02 terminal to the T-phase second branch winding 22T. The T-phase third base winding 32T outputs a voltage having an opposite phase to the voltage output from the T terminal of the T-phase main winding 10T from the S02 terminal to the R-phase second branch winding 22R.

[0075] The R-phase third base winding 33R outputs a voltage from the S03 terminal to the T-phase third branch winding 23T that is in phase with the voltage output from the R terminal of the R-phase main winding 10R. The S-phase third base winding 33S outputs a voltage from the T03 terminal to the R-phase third branch winding 23R that is in phase with the voltage output from the S terminal of the S-phase main winding 10S. The T-phase third base winding 33T outputs a voltage from the R03 terminal to the S-phase third branch winding 23S that is in phase with the voltage output from the T terminal of the T-phase main winding 10T.

[0076] [Variation 2] Next, a transformer device 3B, which is a modified example 2 of the transformer device 3, will be described in detail with reference to Figures 19 and 20. In the transformer device 3A according to the embodiment, the main winding 10 and the neutral point N of each base winding are connected, and any harmonics are removed by a single transformer. The transformer device 3B according to the modified example 2 differs from the transformer device 3A in that the main winding 10 and the neutral point N of each base winding are not connected, and any harmonics are removed by the same number of transformers as the number of systems.

[0077] 19 is a diagram illustrating an example of the configuration of the secondary windings of a transformer device 3B according to Modification 2. The transformer device 3B includes a first transformer TR1, a second transformer TR2, a third transformer TR3, and a fourth transformer TR4 as components. The first transformer TR1 includes a main winding 10. The second transformer TR2 includes a first base winding 31 and a first branch winding 21. The third transformer TR3 includes a second base winding 32 and a second branch winding 22. The fourth transformer TR4 includes a third base winding 33 and a third branch winding 23. Unlike the transformer device 3A, the main winding 10, the first base winding 31, the second base winding 32, and the third base winding 33 are not connected at their neutral point N. The primary winding, the winding provided in the first transformer TR1, the winding provided in the second transformer TR2, the winding provided in the third transformer TR3, and the winding provided in the fourth transformer TR4 are magnetically coupled to one another.

[0078] Fig. 20 is a diagram for explaining the phases on the secondary side of the first transformer TR1 to the fourth transformer TR4 included in the transformer device 3B according to Modification 2. Fig. 20 shows the phase of the power output from each winding with reference to the phase of the power output from the R-phase main winding 10R.

[0079] The first transformer TR1 supplies voltages having a phase difference of 120° from the R, S, and T terminals to the first system. The second transformer TR2 supplies voltages having a phase difference of 120° and a phase difference of 36° from the voltage output from the first transformer TR1 from the R1, S1, and T1 terminals to the second system. The third transformer TR3 supplies voltages having a phase difference of 120° from the voltage output from the first transformer TR1 from the R2, S2, and T2 terminals to the third system. The fourth transformer TR4 supplies voltages having a phase difference of 120° from the voltage output from the first transformer TR1 from the R3, S3, and T3 terminals to the fourth system. The fourth transformer TR4 supplies voltages having a phase difference of 120° from the voltage output from the first transformer TR1 from the R3, S3, and T3 terminals ...36+41.15+36=113.15° from the voltage output from the first transformer TR1 from the R3, S3, and T3 terminals.

[0080] [Summary of the embodiment and modifications] According to the above-described embodiment, the transformer device 3 includes an R-phase main winding 10, an S-phase main winding 10, and a T-phase main winding 10, which are main windings wound around an R-phase core, an S-phase core, and a T-phase core, respectively corresponding to the U-phase, V-phase, and W-phase output on the secondary side of the three-phase AC input to the primary side, and an R-phase branch winding, an S-phase branch winding, and a T-phase branch winding, the number of which corresponds to the number of harmonics to be removed, wound around the R-phase core, the S-phase core, and the T-phase core. The voltages output from each main winding 10 and each branch winding are divided into pairs, and the pair phase difference, which is the phase difference between the voltages included in the pair, is a value corresponding to the order of the harmonic to be removed. Of the voltages output from each main winding 10 and the voltages output from each branch winding, voltages with a phase difference of approximately 120° are supplied to the same system, while the two voltages included in each pair are supplied to different systems. The above-described transformer device 3 can use three-phase power with phases that differ by 120° in each system while removing odd-numbered harmonic components of any order. Furthermore, the transformer device 3 can suppress harmonic components of orders other than those to be removed. Therefore, the transformer device 3 can suppress harmonic components without using expensive harmonic suppression equipment, thereby enabling inexpensive harmonic suppression.

[0081] Furthermore, according to the above-described embodiment, the following equation is satisfied when the pair phase difference is P, the order of the harmonic to be removed is A, and an arbitrarily determined positive odd number is K. According to the following equation, the pair phase difference P for removing any harmonic can be obtained, and therefore, the transformer device 3 that suppresses any odd harmonic component can be easily designed.

[0082]

number

[0083] Furthermore, according to the above-described embodiment, when there are multiple harmonics to be removed, the pairing method differs for each of the harmonics to be removed. Since the pairing method differs for each of the harmonics to be removed, the phase difference between the pairs can be set to the pair phase difference P of one of the harmonics to be removed. Therefore, the transformer device 3 according to the embodiment can remove multiple harmonics.

[0084] Furthermore, according to the above-described embodiment, when the first voltage is a reference voltage among the voltages output from each main winding 10 and each branch winding, the second voltage is a voltage having a pair phase difference P between the first voltage and the second voltage, a value corresponding to the order of the first harmonic, which is one of the multiple harmonics to be removed, the third voltage is a voltage having a phase difference of approximately 120° from the first voltage or the second voltage but not the first or second voltage, and the fourth voltage is a voltage having a pair phase difference between the third voltage and the first voltage and the second voltage and the fourth voltage, a value corresponding to the order of the second harmonic, which is one of the multiple harmonics to be removed but not the first harmonic, and the first voltage, second voltage, third voltage, and fourth voltage are each supplied to a different system. By determining the phase differences of the voltages as described above, two harmonics can be removed. Furthermore, by repeating the above-described method for determining the voltage phase difference, three or more harmonics can be removed. Therefore, by using the above-described method for determining the voltage phase difference, any number of harmonics of any order can be removed.

[0085] Furthermore, according to the above-described embodiment, the branch windings of the first branch winding 21, the second branch winding 22, and the third branch winding 23 are phasors that indicate the phase difference of the voltages output from the branch windings with respect to the neutral point N of the main winding 10. The end points (opposite the neutral point N) of the phasors are located on circumscribed circles that pass through the end points of the vectors that indicate the phase differences of the voltages output from the R-phase, S-phase, and T-phase main windings with respect to the neutral point N. By decomposing the phasors into at least one of R-phase, S-phase, and T-phase vectors, the branch positions on the base windings from which the branch windings branch, the number of turns, and the phase of the core to be wound are determined. By determining the branch positions on the windings, the number of turns, and the phase of the core to be wound using the above-described method, it is possible to easily configure windings that output voltages with a predetermined phase difference. Furthermore, in the transformer device 3 in which the branch positions of the windings are determined using the above-described method, the branch windings are formed by branching off from the main winding 10 or the base winding 11. By forming the branch windings by branching off from the main winding 10 or the base winding 11, the transformer device 3 can be configured with a single transformer. Furthermore, the branch windings can be made thinner than the main winding 10 or the base winding 11. By making the branch windings thinner, the transformer device 3 can use less material and therefore be cheaper. Furthermore, by making the branch windings thinner, the transformer device 3 can be made more compact, and the space required for installation can be reduced.

[0086] Furthermore, according to the above-described embodiment, the phase vectors for the branch windings are resolved so that the number of turns from the branch position of the branch base winding (main winding 10 or base winding 11) of the branch winding to the branch position of the branch winding on the branch base winding is equal to or greater than the number of turns of the branch winding. That is, the phase vectors for the branch windings are resolved so that the number of turns of the branch windings is reduced. Because the branch windings have a smaller wire diameter than the main winding 10 or base winding 11, if the load balance of each system is disrupted, a large voltage drop occurs, resulting in the output of a voltage with a phase difference different from the specified phase difference. By reducing the number of turns of the branch windings, the influence of the voltage drop in the branch windings can be suppressed. Therefore, the transformer device 3 with a small number of turns of the branch windings can eliminate harmonics even if the load balance is disrupted.

[0087] Furthermore, according to the above-described embodiment, the wire diameter of the branch winding is determined so that the allowable current value is a predetermined percentage greater than the rated current value predetermined for the branch winding. Specifically, the wire diameter of the branch winding is increased so that the allowable current of the branch winding is 1.2 times or more the rated current. Increasing the wire diameter of the winding reduces the resistance of the winding and can suppress the effects of voltage drop. Therefore, a transformer device 3 with a branch winding having a large wire diameter can eliminate harmonics even when the load balance is disrupted.

[0088] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design modifications can be made without departing from the spirit of the present invention. Furthermore, the configurations described in the above-described embodiments and examples can be combined. [Explanation of symbols]

[0089] 1...power receiving and distribution equipment, 2...high voltage three-phase power supply, 3...transformer device, 10...main winding, 11...base winding, 21...first branch winding, 22...second branch winding, 23...third branch winding, 31...first base winding, 32...second base winding, 33...third base winding, N...neutral point

Claims

1. an R-phase main winding, an S-phase main winding, and a T-phase main winding, which are main windings wound around an R-phase core, an S-phase core, and a T-phase core, respectively corresponding to a U-phase, a V-phase, and a W-phase, which are output to a secondary side of the three-phase AC input to the primary side; an R-phase branch winding, an S-phase branch winding, and a T-phase branch winding, the number of which corresponds to the number of harmonics to be removed, and which are wound on an R-phase core, an S-phase core, and a T-phase core; Equipped with a pair of voltages determined by dividing the voltages output from the main windings and the voltages output from the branch windings into two pairs, the pair phase difference being the phase difference between the voltages included in the pair, is a value corresponding to the order of the harmonic to be removed, The voltages output from the main windings and the voltages output from the branch windings, which have a phase difference of approximately 120°, are supplied to the same system, In each of the pairs, the two voltages included in the pair are supplied to different systems. Transformer device.

2. When the pair phase difference is P, the order of the harmonic to be removed is A, and an arbitrarily determined positive odd number is K, the following formula is satisfied: The transformer device according to claim 1 . [Equation 1]

3. When there are multiple harmonics to be removed, the pairing method differs for each harmonic to be removed. The transformer device according to claim 1 .

4. When any one of the voltages output from each of the main windings and each of the branch windings as a reference voltage is defined as a first voltage, a voltage having a pair phase difference between the first voltage and the second voltage that corresponds to the order of a first harmonic that is one of a plurality of harmonics to be removed is defined as a second voltage, a voltage not having a phase difference of approximately 120° with the first voltage or the second voltage but excluding the first voltage and the second voltage is defined as a third voltage, and a voltage having a pair phase difference between the third voltage and the third voltage that corresponds to the order of the first harmonic is defined as a fourth voltage, the first voltage and the third voltage, and the second voltage and the fourth voltage have a pair phase difference of a value corresponding to the order of a second harmonic, which is any one of a plurality of harmonics to be removed excluding the first harmonic; the first voltage, the second voltage, the third voltage, and the fourth voltage are supplied to different systems. The transformer device according to claim 1 .

5. The branch windings are phase vectors that indicate the phase difference of the voltages output from the branch windings with respect to the neutral point of the main winding, and the end points of the phase vectors are located on circumscribed circles that pass through the end points of vectors that indicate the phase differences of the voltages output from the R-phase, S-phase, and T-phase main windings with respect to the neutral point. By decomposing the phase vector into at least one of R-phase, S-phase, and T-phase vectors, the branch positions on the windings from which the branch windings branch, the number of turns, and the phases of the cores to be wound are determined. The transformer device according to any one of claims 1 to 4.

6. The phase vector for the branch winding is resolved such that the number of turns from the position where the branch base winding branches out to the branch position of the branch winding on the branch base winding is equal to or greater than the number of turns of the branch winding. The transformer device according to claim 5 .

7. The wire diameter of the branch winding is determined so that the allowable current value is larger by a predetermined percentage than the rated current value predetermined for the branch winding. The transformer device according to claim 5 .

8. A transformer device comprising: the transformer device according to any one of claims 1 to 4; Power receiving and distribution equipment.

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