Method for installing a power conversion device and power conversion system

Abstract

This invention provides a method for installing a power conversion device that reduces radiated noise. [Solution] The method for installing a power converter includes a power converter having a power converter circuit and a housing that covers the power converter circuit, and a power converter that supplies power to the outside of the housing, and the power converter is installed such that the shortest distance between the wiring connected to the power converter circuit and led out from the housing and the conductor facing the wiring is 0.4 m or less.

Description

Technical Field

[0001] The present disclosure relates to a method for installing a power conversion device and a power conversion system.

Background Art

[0002] When performing signal transmission between a plurality of housings of electronic devices via a cable, it is known to arrange the cable in close contact with and along one or both of the housing surfaces of the plurality of housings (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Radiated noise is generated from the wiring led out from a power conversion device having a power conversion circuit.

[0005] An object of the present disclosure is to provide a method for installing a power conversion device and a power conversion system that reduce radiated noise.

Means for Solving the Problems

[0006] An embodiment of the present disclosure includes a power conversion circuit and a housing that covers the power conversion circuit, prepares a power conversion device that supplies power outside the housing, and installs the power conversion device such that the shortest distance between the wiring connected to the power conversion circuit and led out from the housing and a conductor facing the wiring is 0.4 m or less. This is a method for installing a power conversion device.

[0007] Embodiments of the present disclosure are power conversion systems comprising: a power conversion circuit; a housing covering the power conversion circuit; a power conversion device that supplies power to the outside of the housing; and wiring connected to the power conversion circuit and led out from the housing, wherein the shortest distance between the wiring and a conductor facing the wiring is 0.4 m or less. [Effects of the Invention]

[0008] According to this disclosure, a method for installing a power conversion device and a power conversion system that reduce radiated noise can be provided. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a block diagram showing a power conversion system according to the first embodiment. [Figure 2] Figure 2 is a block diagram showing a solar power generation system in which the power conversion system in the first embodiment is used. [Figure 3] Figure 3 is a front view showing the installation of the power conversion system according to the first embodiment. [Figure 4] Figure 4 is a cross-sectional view showing the installation of the power conversion system according to the first embodiment. [Figure 5] Figure 5 shows the electric field strength radiated from the wiring in the comparative example. [Figure 6] Figure 6 shows the electric field strength radiated from the wiring in the embodiment. [Figure 7] Figure 7 shows the electric field strength as a function of position. [Figure 8] Figure 8 shows the electric field strength as a function of position. [Figure 9] Figure 9 shows the ratio of electric field strength to distance D1. [Figure 10] Figure 10 is a flowchart showing the installation method of the power conversion device according to the first embodiment. [Figure 11] Figure 11 is a cross-sectional view showing the installation of the power conversion system according to the second embodiment. [Modes for carrying out the invention]

[0010] The embodiments will be described below with reference to the attached drawings. However, this disclosure is not limited to these examples, and all modifications are intended to be included in the meaning and scope equivalent to the claims, as indicated by the claims.

[0011] In the description and drawings of each embodiment, components having substantially the same or corresponding functional configurations may be denoted by the same reference numerals, thereby omitting redundant explanations. Furthermore, for ease of understanding, the scale of each part in the drawings may differ from that of actual parts.

[0012] Power electronics equipment such as power converters generate significant radiated noise. This noise is emitted not only from the power converter itself but also from the wiring connected to it. Possible countermeasures for radiated noise include the introduction of noise filters or the use of shielded cables. However, these countermeasures have problems in terms of cost and workability. In particular, when the wiring is power wiring, the noise filters and shielded cables become large depending on the current capacity. In the following embodiment, radiated noise can be reduced by devising a method of installing the power converter. (First Embodiment)

[0013] Figure 1 is a block diagram illustrating a power conversion system according to the first embodiment. As shown in Figure 1, the power conversion system 100 comprises a power conversion device 10 and wiring 15A to 15C. The power conversion device 10 is a device that supplies power to the outside, and is, for example, a solar power conditioner (PCS: Power Conditioning System). The power conversion device 10 comprises a housing 11, a power conversion circuit 12, and a control circuit 13. The housing 11 covers the power conversion circuit 12 and the control circuit 13 and is made of a conductive material such as a metal plate. The housing 11 is grounded via the wiring 15A to 15C and may function as a shield.

[0014] The power conversion circuit 12 converts the power supplied from the wiring 15A and outputs it from the wiring 15B. The power conversion circuit 12 is, for example, an inverter that converts DC power into AC power. The power conversion circuit 12 may be a converter that converts AC power into DC power, a converter that converts the frequency of power, or a converter that converts the voltage of power. The power conversion circuit 12 converts power, for example, by switching of switching elements. The control circuit 13 controls the power conversion circuit 12.

[0015] The wirings 15A to 15C are led out from the housing 11 of the power conversion device 10. The wiring 15A is an input wiring that supplies power to the power conversion circuit 12 of the power conversion device 10. The wiring 15B is an output wiring that outputs power from the power conversion circuit 12 of the power conversion device 10. The wiring 15C is a signal wiring that transmits a signal for controlling the power conversion device 10.

[0016] FIG. 2 is a block diagram showing a photovoltaic power generation system in which the power conversion system according to the first embodiment is used. As shown in FIG. 2, the photovoltaic power generation system 102 includes a power conversion device 10, a photovoltaic module 25, a control device 26, and a high-voltage transformer 27. The photovoltaic module 25 has a plurality of solar cells and generates DC power by sunlight. The voltage of the DC power is, for example, 100V to several kV. The DC power is supplied to the power conversion device 10 by the wiring 15A which is a DC power line. The power conversion device 10 converts the DC power supplied by the wiring 15A into AC power and outputs the AC power from the wiring 15B. The voltage of the AC power is, for example, several hundred volts to several kV. The AC power is, for example, three-phase AC. The high-voltage transformer 27 converts the voltage of the AC power supplied by the wiring 15B into a high voltage and supplies the AC power to the high-voltage power distribution system 28. The voltage of the high-voltage power distribution system 28 is, for example, 6.6 kV.

[0017] FIG. 3 is a front view showing the installation of the power conversion system according to the first embodiment. FIG. 4 is a cross-sectional view showing the installation of the power conversion system according to the first embodiment. The normal direction to the bottom surface 23 is defined as the Z direction, the normal direction to the front surface 21 of the structure 20 is defined as the X direction, and the direction orthogonal to the X direction and the Y direction is defined as the Y direction.

[0018] As shown in FIGS. 3 and 4, the structure 20 is installed on the bottom surface 23. The structure 20 is, for example, a wall of a building such as a building. The bottom surface 23 is, for example, the ground. A conductor 22 is provided in the structure 20. When the structure 20 is made of reinforced concrete, the conductor 22 is, for example, a reinforcing bar. The structure 20 may also be a steel plate or a steel sheet. In this case, the conductor 22 is integral with the structure 20. The power conversion device 10 is installed on the structure 20.

[0019] The wiring 15 is led out from the housing 11 of the power conversion device 10 and extends along the structure 20. The wiring 15 is fixed to the structure 20 by, for example, a fixture 16. The fixture 16 may not be provided. Let the shortest distance between the conductor 22 and the wiring 15 be the distance D1. Let the distance between the housing 11 and the fixture 16 be the distance D2. Let the distance between the structure 20 and the wiring 15 at the location where the wiring 15 is led out from the housing 11 be the distance D3. Let the distance between the structure 20 and the wiring 15 at the location where the fixture 16 fixes the wiring 15 be the distance D4. Let the distance between the power conversion device 10 and the bottom surface 23 be the distance D5. As an example, the distance D1 is 40 cm or less, the distance D2 is 1 m or less, the distance D3 is 20 cm, the distance D4 is 5 cm, and the distance D5 is 1 m or more.

[0020] In the power conversion system 100, radiated noise is a problem. For example, if the power conversion circuit 12 has switching elements, noise generated in the power conversion circuit 12 is conducted to the wiring 15 or the shield of the wiring 15 and radiated into the surrounding space. Even when the switching frequency of the power conversion circuit 12 is several tens of kHz, the noise at the resonant frequency among the harmonic components of the switching frequency becomes large. Noise radiated from the power conversion device 10, in particular noise in the range of several tens of MHz to several tens of MHz, interferes with wireless communication (for example, Nikkei Shimbun article dated September 20, 2024, "Solar power generation interferes with disaster prevention radio; problem may worsen with increased panel installation" https: / / www.nikkei.com / article / DGXZQOUC043D90U4A900C2000000). In addition, the radiated noise level is large in the power conversion device 10 in the range of 30 MHz to 100 MHz. Based on these considerations, we defined the frequency range requiring noise countermeasures as 30 MHz to 150 MHz and investigated the conditions for reducing noise in this frequency range.

[0021] (simulation) The noise radiated from wiring 15 was simulated using an electromagnetic field simulation. The noise frequency was set to 30 MHz. Simulations were performed for a comparative example without conductor 22 and for an example in which conductor 22 was provided as a wall surface of structure 20 on the back of power converter 10.

[0022] Figure 5 shows the electric field strength radiated from the wiring in the comparative example. Figure 6 shows the electric field strength radiated from the wiring in the embodiment. The direction of the electric field is indicated by the direction of the arrow, and the electric field strength is indicated by the length and thickness of the arrow. The thick arrow near wiring 15 indicates an electric field strength of 30 V / m to 50 V / m. The position of wiring 15 in the X direction is defined as 0m, the X direction from 0m is considered positive, and the -X direction from 0m is considered negative.

[0023] As shown in Figure 5, the wiring 15 extends downward from the power converter 10. The electric field strength is high around the wiring 15. The electric field strength is high from the wiring 15 close to the power converter 10, and low from the wiring 15 further away from the power converter 10. The electric field strength is approximately symmetrical with respect to the wiring 15.

[0024] As shown in Figure 6, a conductor 22 is provided on the back of the power converter 10. The position of the conductor 22 is -0.2m. That is, the distance D0 between the conductor 22 and the wiring 15 is 0.2m. The electric field strength is greater at positions negative to the wiring 15 and smaller at positions positive to the wiring 15.

[0025] Figure 7 shows the electric field strength as a function of position. The position is the position in the X direction, with the position of the wiring 15 in Figures 5 and 6 being 0. The electric field strength is shown at position X, which is at a distance D6 in the -Z direction from the bottom surface of the housing 11 of the power converter 10 in Figures 5 and 6. The distance D6 is 20 cm.

[0026] As shown in Figure 7, in the comparative example, the electric field strength is symmetrical with respect to position 0. In the example, the electric field strength is greater than in the comparative example at negative positions and smaller than in the comparative example at positive positions. The electric field strength in the example at position 1m is 1 / 3 of that in the comparative example.

[0027] Figure 8 shows the electric field strength as a function of position. In Figure 8, the position is shown logarithmically up to 3m. As shown in Figure 8, even at a position of 3m, the electric field strength of the embodiment is smaller than that of the comparative example. Since the electric field strength is inversely proportional to the distance from the radiation source (wiring 15), it is considered that the electric field strength of the embodiment is smaller than that of the comparative example at positions greater than 3m. In this way, by providing a conductor near wiring 15, the radiated noise from wiring 15 can be reduced.

[0028] This noise reduction effect increases as the distance D0 between the conductor 22 and the wiring 15 decreases, localizing the electromagnetic field and reducing the electric field strength at a distance. On the other hand, as the distance D0 between the conductor 22 and the wiring 15 increases, the properties of the electromagnetic field become stronger, and it is assumed that the electric field strength at a distance will increase. Therefore, the noise reduction effect was simulated by changing the distance D0. The simulation was performed for noise frequencies of 30 MHz and 150 MHz. The noise reduction effect was expressed as the ratio of the electric field strength of the example to the electric field strength of the comparative example at the position 3 m in Figure 7.

[0029] Figure 9 shows the ratio of the electric field strength to the distance D0. It indicates that when the electric field strength ratio is less than 0 dB, the conductor 22 is effective, and when the electric field strength ratio is 0 dB or more, the conductor 22 increases the noise.

[0030] As shown in Figure 9, both at 30 MHz and 150 MHz, the electric field strength ratio increases and noise increases as the distance D0 increases. At 30 MHz, there is a noise reduction effect when the distance D0 is 0.4 m or less, and at 150 MHz, there is a noise reduction effect when the distance D0 is 1.4 m or less. The reason why the distance D1 at which noise can be reduced decreases as the frequency increases is thought to be because the wavelength becomes shorter as the frequency increases, thus shortening the distance at which the properties of radio waves become stronger.

[0031] (Installation method for power converters) Based on the above, the method for installing the power converter will now be described. Figure 10 is a flowchart showing the method for installing the power converter according to the first embodiment. As shown in Figure 10, the power converter 10 is prepared (step S10). As shown in Figure 1, the power converter 10 has a power conversion circuit 12 and a housing 11 that covers the power conversion circuit 12.

[0032] Next, the power converter 10 is installed (step S12). The noise frequency to be reduced is between 30 MHz and 150 MHz. As shown in Figure 9, the higher the frequency, the shorter the distance D0 must be to achieve noise reduction. Therefore, the shortest distance D1 between the wiring 15 led out from the housing 11 and the conductor 22 facing the wiring 15 is set to 0.4 m or less, which is effective in reducing noise at 150 MHz. This reduces the radiation of noise below 150 MHz generated in the power converter 10 from the wiring 15, as shown in Figure 9.

[0033] From the viewpoint of further reducing noise, the distance D1 may be 0.3m or less, 0.2m or less, or 0.1m or less. If the structure 20 is made of reinforced concrete, it is not possible to know where the reinforced concrete conductor 22 is located within the structure 20. Therefore, it is preferable to use a metal detector to determine the location of the reinforced concrete and then install the wiring 15.

[0034] From the viewpoint of reducing noise, the conductor 22 may be grounded. The conductor 22 is grounded by being connected directly or via a conductor to a grounding electrode, the ground, or a grounding point of the structure 20. Alternatively, the conductor 22 may be connected to a grounding point of the structure 20. If the maximum dimension of the conductor 22 is greater than or equal to one wavelength of noise, the conductor 22 can be considered substantially grounded. Wavelengths increase as the frequency decreases. Therefore, the wavelength at 30 MHz, where the noise frequency is lowest, is adopted. When the noise frequency is 30 MHz, the wavelength corresponds to approximately 10 m. Therefore, if the conductor 22 is not grounded, the maximum dimension of the conductor 22 may be 10 m or more. The maximum dimension of the conductor 22 is preferably 20 m or more, and more preferably 30 m or more.

[0035] As shown in Figures 4 and 5, the noise propagating through the wiring 15 in a location close to the power converter 10 is large. Also, the wavelength at 150 MHz is 2 m, and if large noise propagates within this wavelength, the radiated noise will also be large. Therefore, from the viewpoint of reducing noise radiation from the wiring 15, in Figure 4, it is preferable to make the shortest distance D1 between the wiring 15 and the conductor 22 0.4 m or less in the range R1 where the distance from the housing 11 is 1 m or less (preferably 0.5 m or less).

[0036] From the viewpoint of reducing radiated noise, it is preferable that the length of the wiring 15 is large enough so that the distance between the wiring 15 and the conductor 22 is 0.4 m or less within range R1. Therefore, in range R1 where the distance from the housing 11 is 1 m or less, the length R2 of the wiring 15 so that the distance between the wiring 15 and the conductor 22 is 0.4 m or less is preferably 0.3 m or more, and more preferably 0.5 m or more.

[0037] Noise is radiated from any of the wirings 15A to 15C. Therefore, it is preferable that the shortest distance D1 between at least one of the wirings 15A to 15C and the conductor 22 be 0.4m or less. In particular, noise is easily radiated from wiring that transmits high voltage power or wiring that has shielding. Therefore, it is preferable that the shortest distance D1 between those wirings and the conductor 22 be 0.4m or less. Multiple wirings 15A to 15C may be provided. The core wires of wirings 15A to 15C may be one or multiple. Wirings 15A to 15C may or may not have shielding. If multiple wirings 15 are provided, it is preferable that the shortest distance D1 between all of the wirings 15 and the conductor 22 be 0.4m or less.

[0038] Noise is also radiated from wiring other than wiring 15A to 15C. In addition to wiring 15A to 15C, the shortest distance D1 between at least one of the following wirings and conductor 22 may be 0.4m or less: neutral wire, ground wire, auxiliary power wiring, connection wiring, detection signal wiring, and communication wire. The neutral wire is the wiring for connecting the power converter 10 to the neutral point of the transformer. The ground wire is the wiring for protective grounding of the power converter 10. The auxiliary power wiring is the wiring that supplies auxiliary power to equipment (such as a fan or brake unit) inside the power converter 10. The connection wiring is the wiring that connects the power converter 10 to peripheral equipment such as a reactor or filter. The detection signal wiring is the wiring that transmits detection signals from sensors or detection equipment. The communication wire is the wiring that enables communication between the power converter 10 and external equipment.

[0039] As shown in Figures 3 and 4, when the power converter 10 is installed in a fixed structure, the conductor 22 may be part of the structure. In this case, a part of the structure (for example, reinforcing bars) can be used as the conductor 22. Therefore, it is not necessary to newly install the conductor 22.

[0040] The wiring 15 may be fixed to the building using a fastener 16. This allows the wiring 15 to be brought closer to the conductor 22. The distance D2 between the housing 11 and the fastener 16 is preferably 1 m or less, and more preferably 0.5 m or less.

[0041] The power converter 10 may be installed outdoors or indoors. When the power converter 10 is installed outdoors, radiated noise is a particular problem. Therefore, when the power converter 10 is installed outdoors, it is preferable to set the distance D1 to 0.4m or less. The structure 20 may be the ceiling, floor, columns, roof, etc. of a building, or it may be a fence.

[0042] The power converter 10 is, for example, a device that converts electricity and supplies it to external equipment or a power supply system. The power converter 10 may also be used in power generation systems other than the solar power generation system shown in Figure 2, industrial drive systems, industrial power supply systems, railway vehicle power conversion systems, EV (Electric Vehicle) charging systems, or UPS (Uninterruptible Power Supply) systems, etc. In particular, if the maximum DC voltage inside the power converter is large, such as 400V or more, the radiated noise will be large. Therefore, it is preferable to set the distance D1 to 0.4m or less.

[0043] Figure 11 is a cross-sectional view showing the installation of a power conversion system according to the second embodiment. As shown in Figure 11, in the power conversion system 104 of the second embodiment, the power conversion device 10 is installed on a support 18 separate from the structure 20. The support 18 is located near the structure 20. The shortest distance D1 between the wiring 15 and the conductor 22 is 0.4 m or less. As in the second embodiment, the power conversion device 10 is installed on the support 18, and the support 18 may be installed near a building. This improves the flexibility of the installation of the power conversion device 10. The support 18 may be a conductor 22 as long as the support 18 is conductive and can be installed on it. The other configurations are the same as in the first embodiment and are omitted from the description.

[0044] Although embodiments have been described above, the present invention is not limited to the embodiments described above. Various modifications and improvements, such as combinations or substitutions with some or all of other embodiments, are possible within the scope of this disclosure. [Explanation of Symbols]

[0045] 10 Power converter 11 cabinets 12 Power Conversion Circuit 13 Control circuits 15, 15A, 15B, 15C wiring 20 Structure 22 Conductors 21 Front 23 Bottom

Claims

1. A power conversion device is prepared, comprising a power conversion circuit and a housing that covers the power conversion circuit, and which supplies power to the outside of the housing. The power conversion device is installed such that, within a distance of 1 m or less from the housing, the shortest distance between the wiring connected to the power conversion circuit and led out from the housing and the conductor facing the wiring is 0.4 m or less, and within a distance of 1 m or less from the housing, the length of the wiring such that the distance between the wiring and the conductor is 0.4 m or less is 0.3 m or more. A method for installing a power converter, wherein the aforementioned conductor is grounded.

2. A power conversion device is provided, comprising a power conversion circuit and a housing that covers the power conversion circuit, wherein power is supplied to the outside of the housing, The power conversion device is installed such that, within a distance of 1 m or less from the housing, the shortest distance between the wiring connected to the power conversion circuit and led out from the housing and the conductor facing the wiring is 0.4 m or less, and within a distance of 1 m or less from the housing, the length of the wiring such that the distance between the wiring and the conductor is 0.4 m or less is 0.3 m or more. A method for installing a power converter, wherein the conductor is not grounded and the maximum length of the conductor is 10 m or more.

3. The method for installing a power converter according to claim 1 or 2, wherein the distance between the wiring and the conductor at the point where the wiring is led out from the housing is longer than the shortest distance.

4. After determining the position of the reinforcing bars within the reinforced concrete, The power converter is installed such that, within a distance of 1 m or less from the housing, the shortest distance between the wiring connected to the power conversion circuit and led out from the housing and the conductor facing the wiring is 0.4 m or less, and within a distance of 1 m or less from the housing, the length of the wiring such that the distance between the wiring and the conductor is 0.4 m or less is 0.3 m or more. A method for installing a power converter according to claim 1 or 2.

5. The method for installing a power converter according to claim 1 or 2, wherein the wiring comprises at least one of the following: an input wiring that supplies power to the power converter; an output wiring that outputs power from the power converter; a neutral wire connected to the power converter; a grounding wire that protects the power converter; an auxiliary power wiring that supplies auxiliary power; a connection wiring that connects the power converter to peripheral equipment; a signal wiring that transmits a signal to control the power converter; a detection signal wiring that transmits a detection signal; and a communication line that communicates between the power converter and an external device.

6. The method for installing a power converter according to claim 1 or 2, wherein the conductor is part of the building on which the power converter is installed.

7. The installation method according to claim 6, wherein the wiring is fixed to the building using fasteners.

8. The method for installing a power converter according to claim 1 or 2, wherein the power converter is installed on a support, and the support is installed near a building having the conductor.

9. A power conversion device comprising a power conversion circuit and a housing covering the power conversion circuit, and which supplies power to the outside of the housing, Wiring connected to the power conversion circuit and led out from the housing, Equipped with, Within a range of 1 m or less from the housing, the shortest distance between the wiring and the conductor facing the wiring is 0.4 m or less, and within a range of 1 m or less from the housing, the length of the wiring such that the distance between the wiring and the conductor is 0.4 m or less is 0.3 m or more. The aforementioned conductor is grounded in a power conversion system.

10. A power conversion device comprising a power conversion circuit and a housing covering the power conversion circuit, wherein power is supplied to the outside of the housing, Wiring connected to the power conversion circuit and led out from the housing, Equipped with, Within a range of 1 m or less from the housing, the shortest distance between the wiring and the conductor facing the wiring is 0.4 m or less, and within a range of 1 m or less from the housing, the length of the wiring such that the distance between the wiring and the conductor is 0.4 m or less is 0.3 m or more. A power conversion system in which the conductor is not grounded and the maximum length of the conductor is 10 m or more.

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