CN111316555A - Power conversion device and power generation system - Google Patents

Abstract

The power conversion device includes: a detection circuit that detects an insulation resistance value on a negative electrode side and an insulation resistance value on a positive electrode side of the direct-current power supply; and an insulation distance securing element provided between the detection circuit and the ground point for securing an insulation distance between the detection circuit and the ground point.

Description

Power conversion device and power generation system

technical field

The present invention relates to a power conversion device, and more particularly, to a power conversion device and a power generation system including a detection circuit for detecting the insulation resistance value of the negative electrode side and the insulation resistance value of the positive electrode side of a DC power supply.

Background technique

Conventionally, there has been known a ground fault detection device including a detection unit that detects a ground fault (insulation resistance value) of a DC power supply. Such a ground fault detection device is disclosed, for example, in Japanese Patent Laid-Open No. 2012-119382.

Japanese Patent Laid-Open No. 2012-119382 discloses a solar cell system including: a solar cell string formed by connecting a plurality of solar cell modules in series; and a solar cell array in which It is formed by connecting solar cells in series and parallel. In this solar cell system, a switch unit for electrically disconnecting a solar cell array or a solar cell string (hereinafter referred to as a DC power supply) from the solar cell system is provided. In addition, this solar cell system is provided with a detection unit that detects a ground fault of the DC power supply in a state where the DC power supply is electrically disconnected from the solar cell system.

In Japanese Patent Laid-Open No. 2012-119382, the detection unit includes: a detection resistor provided between the DC power supply and a ground; and a voltage detector on one side (DC power supply side) and the other side of the detection resistor (Ground point) connection to detect the voltage drop between one side and the other side of the sense resistor. Then, the voltage detector detects a voltage drop between one side and the other side of the detection resistor in a state where the positive side of the DC power supply and the ground point are electrically connected. In addition, the voltage detector detects a voltage drop between one side and the other side of the detection resistor in a state where the negative electrode side of the DC power supply and the ground point are electrically connected. Then, based on the results of these voltage drops, the insulation resistance value is calculated. In addition, the presence or absence of a ground fault is detected based on the insulation resistance value.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2012-119382

SUMMARY OF THE INVENTION

Invention to solve problem

However, since the voltage detector of Japanese Patent Laid-Open No. 2012-119382 is connected to the other side (the ground point) of the detection resistor, it is considered that the insulation distance between the voltage detector and the ground point is relatively small (the potential of the voltage detector is close to the ground point). ground potential). Therefore, it is necessary to secure a relatively large insulation distance between the voltage detector and other devices. Therefore, there is a problem that the size of the apparatus is increased because other devices cannot be arranged near the voltage detector (detection circuit).

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a device capable of suppressing an increase in size of the apparatus due to the inability to arrange other devices near a detection circuit for detecting an insulation resistance value. Power conversion device and power generation system.

solution to the problem

In order to achieve the above object, a power conversion device according to a first aspect of the present invention includes: a power conversion unit that converts DC power supplied from a DC power source into AC power; and a detection circuit that is provided between the DC power source and the power conversion unit Between detection of the insulation resistance value of the positive side and the insulation resistance value of the negative side of the DC power supply; and an insulation distance ensuring element, which is arranged between the detection circuit and the ground point to ensure the insulation distance between the detection circuit and the ground point .

The power conversion device according to the first aspect of the present invention includes, as described above, an insulation distance securing element provided between the detection circuit and the ground point for securing the insulation distance between the detection circuit and the ground point. Thereby, the insulation distance between the detection circuit and the ground point can be ensured, so that the potential of the detection circuit becomes a potential different from the ground potential. As a result, the insulation distance required between the detection circuit and other devices becomes relatively small, so that other devices can be arranged in the vicinity of the detection circuit. As a result, it is possible to suppress an increase in size of the apparatus due to the inability to arrange another device in the vicinity of the detection circuit for detecting the insulation resistance value.

In the power conversion device according to the first aspect, it is preferable that the insulating distance securing element includes a chip resistor having a pair of terminals and a resistor body provided between the pair of terminals. With this configuration, the insulating distance can be easily secured by utilizing the space (distance) between the pair of terminals of the chip resistor.

In this case, it is preferable that the insulating distance securing element includes a plurality of chip resistors connected in series with each other. With this configuration, even when the insulating distance cannot be sufficiently secured by one chip resistor, the insulating distance can be sufficiently secured by the plurality of chip resistors connected in series with each other.

In the power conversion device including the above-described plurality of chip resistors connected in series, it is preferable that the plurality of chip resistors are arranged in a straight line. If configured in this way, the distance between one end and the other end of the plurality of chip resistors connected in series changes, unlike a state where the plurality of chip resistors connected in series are not linear (curved, etc.). is relatively large, so the insulation distance can be effectively ensured.

Preferably, the power conversion device in which the insulating distance securing element includes a chip resistor further includes: a first resistor provided between the detection circuit and the positive side of the DC power supply; and a second resistor provided in the detection circuit The insulation distance securing element, the first resistor, and the second resistor are composed of the same chip resistor with respect to the negative side of the DC power supply. With this configuration, the types of components constituting the power conversion device can be reduced compared to the case where the first resistance, the second resistance, and the insulating distance securing elements are formed of different elements.

In this case, it is preferable to further include a detection resistor provided between the first resistor and the second resistor and the insulating distance securing element composed of the chip resistor, and the detection resistor has a resistance value higher than that of the first resistor. The resistance value of the resistor, the second resistor, and the insulating distance securing element constituted by the chip resistor are all small, and the detection circuit is configured to detect the voltage across the detection resistor. With this configuration, even when the insulation resistance value is relatively small, the detection circuit can easily detect the voltage across both ends of the detection resistor having a relatively small resistance value.

In the power conversion device according to the first aspect, it is preferable that the insulation distance securing element is configured to secure the insulation distance between the detection circuit and the ground point such that the potential of the detection circuit with respect to the ground point is electrically suspended . With this configuration, since the potential of the detection circuit with respect to the ground point is in an electrically floating state, other devices can be placed near the detection circuit with the insulation distance being substantially zero.

A power generation system according to a second aspect of the present invention includes a power generation unit that generates power using natural energy, and a power conversion device that converts power supplied from the power generation unit, the power conversion device includes a power conversion unit that converts power from the power generation unit The supplied DC power is converted into AC power; a detection circuit is provided between the power generation part and the power conversion part, and detects the insulation resistance value of the positive electrode side of the power generation part and the insulation resistance value of the negative electrode side; and an insulation distance securing element, which It is arranged between the detection circuit and the ground point to ensure the insulation distance between the detection circuit and the ground point.

The power generation system according to the second aspect of the present invention includes, as described above, an insulation distance securing element provided between the detection circuit and the ground point for securing the insulation distance between the detection circuit and the ground point. Thereby, the insulation distance between the detection circuit and the ground point can be ensured, so that the potential of the detection circuit becomes a potential different from the ground potential. As a result, the insulation distance required between the detection circuit and other devices becomes relatively small, so that other devices can be arranged in the vicinity of the detection circuit. Thereby, it is possible to provide a power generation system capable of suppressing an increase in size of the apparatus due to the inability to arrange another device in the vicinity of the detection circuit for detecting the insulation resistance value.

effect of invention

According to the present invention, as described above, it is possible to suppress an increase in size of the apparatus due to the inability to arrange another device in the vicinity of the detection circuit for detecting the insulation resistance value.

Description of drawings

FIG. 1 is a schematic diagram (1) showing the configuration of a power generation system according to the present embodiment.

FIG. 2 is a schematic diagram ( 2 ) showing the configuration of the power generation system according to the present embodiment.

FIG. 3 is a circuit diagram showing the configuration of the power conversion device (insulation resistance detection unit) according to the present embodiment.

FIG. 4 is a schematic diagram showing the structure of the chip resistor according to the present embodiment.

Detailed ways

Hereinafter, embodiments that embody the present invention will be described based on the drawings.

[this embodiment]

The configuration of the power generation system 100 (power conversion device 20 ) according to the present embodiment will be described with reference to FIGS. 1 to 4 .

As shown in FIGS. 1 and 2 , the power generation system 100 includes a solar panel 10 that generates power using natural energy. In addition, the solar panel 10 is an example of the "power generation part" and "direct current power supply" of a claim.

Further, the power generation system 100 includes a power conversion device 20 (inverter) that converts the power supplied from the solar panel 10 . The power conversion device 20 includes a DC/AC converter 21 (DC/AC) that converts DC power supplied from the solar panel 10 into AC power. In addition, the AC power converted by the DC-AC conversion unit 21 is supplied to the system 201 via the transformer 200 . In addition, the transformer 200 may not be provided in some cases. In addition, the DC-AC conversion unit 21 is an example of the "power conversion unit" in the claims.

In addition, the power conversion device 20 includes an insulation resistance detection unit 30 provided on the input side (the solar panel 10 side) of the DC/AC conversion unit 21 . The insulation resistance detection unit 30 includes a detection circuit (voltage detection circuit) 31 , a relay 32 , a relay 33 , a first resistor 34 , a second resistor 35 , an insulation distance securing element 36 , and a detection resistor 37 . Hereinafter, it demonstrates concretely.

The detection circuit 31 is provided between the solar panel 10 and the DC-AC conversion unit 21 . Further, the detection circuit 31 is configured to detect the insulation resistance value of the positive electrode side and the insulation resistance value of the negative electrode side of the solar panel 10 . Specifically, the relay 32 is provided between the detection circuit 31 and the wiring 41 connecting the positive electrode side (high voltage positive electrode side P) of the solar panel 10 and the DC/AC converter 21 . In addition, a relay 33 is provided between the wiring 42 connecting the negative electrode side (high voltage negative electrode side N) of the solar panel 10 and the DC/AC converter 21 and the detection circuit 31 . In addition, the input side and the output side of the relay 32 (relay 33 ) are insulated from each other.

In addition, as shown in FIG. 3, the detection circuit 31 includes an isolation amplifier 31a. The isolation amplifier 31a refers to an amplifier in which an input portion and an output portion are isolated. Moreover, the power supply circuit 51 which supplies electric power to the isolation amplifier 31a is provided. The power supply circuit 51 is configured to supply electric power to the input side of the isolation amplifier 31a (the side connected to the detection resistor 37 described later).

In addition, as shown in FIGS. 1 and 2 , the power conversion device 20 (insulation resistance detection unit 30 ) includes a first resistor 34 provided between the detection circuit 31 and the positive side (relay 32 ) of the solar panel 10 . In addition, the power conversion device 20 (insulation resistance detection unit 30 ) includes a second resistance 35 provided between the detection circuit 31 and the negative electrode side (relay 33 ) of the solar panel 10 . The first resistor 34 and the second resistor 35 are connected to each other. In addition, the relay 32, the first resistor 34, the second resistor 35, and the relay 33 are connected in series in this order.

Further, the power conversion device 20 (insulation resistance detection unit 30 ) includes a detection resistance 37 provided between the first resistance 34 and the second resistance 35 and an insulation distance securing element 36 described later. Specifically, the detection resistor 37 is provided between the connection point of the first resistor 34 and the second resistor 35 and the insulating distance securing element 36 described later. Further, the detection circuit 31 is configured to detect the voltage across both ends of the detection resistor 37 .

Here, in the present embodiment, the power conversion device 20 (insulation resistance detection unit 30 ) includes the insulation distance securing element 36 provided between the detection circuit 31 and the ground point for securing the detection circuit 31 Insulation distance from ground. Specifically, as shown in FIG. 3 , the insulating distance securing element 36 includes a plurality of chip resistors 60 connected to each other in series. As shown in FIG. 4 , the chip resistor 60 has a pair of terminals 61 and a resistor 62 provided between the pair of terminals 61 . Also, the distance L between the pair of terminals 61 corresponds to the insulation distance.

In addition, in the present embodiment, as shown in FIG. 3 , a plurality of (five) chip resistors 60 are arranged in a linear shape. Thereby, an insulation distance corresponding to the length of the distance L×5 between the pair of terminals 61 is ensured by the insulation distance ensuring element 36 . In addition, the insulating distance securing element 36 is configured to secure the insulating distance between the detection circuit 31 and the ground point so that the detection circuit 31 is in an electrically floating state. For example, by securing an insulation distance corresponding to the length of the distance L×5 by five chip resistors 60 , the electric potential of the detection circuit 31 with respect to the ground point is electrically floated.

In addition, in the present embodiment, the insulating distance securing element 36 , the first resistor 34 , and the second resistor 35 are constituted by the same chip resistor 60 . Specifically, the first resistor 34 is composed of a plurality of (five) chip resistors 60 that are connected in series (arranged in a straight line), similarly to the insulating distance securing element 36 . In addition, the second resistor 35 is constituted by a plurality of (five) chip resistors 60 connected in series (arranged in a linear shape), similarly to the insulation distance securing element 36 . Thereby, the insulation distance between the detection circuit 31 and the positive electrode side of the solar panel 10 is ensured by the first resistor 34 . In addition, the insulation distance between the detection circuit 31 and the negative electrode side of the solar panel 10 is ensured by the second resistor 35 .

In addition, in the present embodiment, the resistance value of the detection resistor 37 is smaller than the resistance value of the first resistor 34 , the second resistor 35 , and the insulation distance securing element 36 including the chip resistor 60 . Specifically, the resistance value of the detection resistor 37 is several hundreds of Ω, and the resistance values of the first resistor 34 , the second resistor 35 , and the insulating distance securing element 36 are each several MΩ. In addition, these resistance values are an example, and each resistance value is not limited to the above-mentioned resistance value.

In addition, as shown in FIG. 3 , other devices other than the detection circuit 31 such as the control circuit 70 are arranged in the vicinity of the detection circuit 31 . Moreover, the power supply circuit 52 which supplies electric power to other equipment, such as the control circuit 70, is provided. Here, when the insulation distance securing element 36 is not provided, the potential of the detection circuit 31 (power supply circuit 51 ) is close to the ground potential, so a predetermined insulation distance needs to be ensured between the power supply circuit 51 and the power supply circuit 52 . On the other hand, in the present embodiment, by providing the insulating distance securing element 36, the potential of the detection circuit 31 (power supply circuit 51) becomes a floating potential (electrically floating state), so that the distance between the power supply circuit 51 and the power supply circuit 52 can be shortened. insulation distance between. In addition, the power supply circuit 51 and the power supply circuit 52 are constituted by, for example, a transformer, and the transformer can be reduced in size by shortening the insulation distance between the power supply circuit 51 and the power supply circuit 52 .

Next, the operation of the insulation resistance detection unit 30 will be described with reference to FIGS. 1 and 2 .

As shown in FIG. 1 , the relay 32 is turned off, and the relay 33 is turned on. Thereby, the ground fault current Ig flows from the positive side of the solar panel 10 to the negative side of the solar panel 10 via the ground point, the insulating distance securing element 36 , the detection resistor 37 , the second resistor 35 and the relay 33 . The voltage value of the ground fault current Ig is detected by the detection circuit 31 . An insulation resistance value Rg is obtained based on this voltage value, and a ground fault on the positive electrode side of the solar panel 10 is detected based on the insulation resistance value Rg.

In addition, as shown in FIG. 2 , the relay 32 is turned on, and the relay 33 is turned off. Thereby, the ground fault current Ig flows from the positive side of the solar panel 10 to the negative side of the solar panel 10 via the relay 32 , the first resistor 34 , the detection resistor 37 , the insulation distance securing element 36 , and the ground point. The voltage value of the ground fault current Ig is detected by the detection circuit 31 . An insulation resistance value Rg is obtained based on this voltage value, and a ground fault on the negative electrode side of the solar panel 10 is detected based on the insulation resistance value Rg.

[Effects of the present embodiment]

In the present embodiment, the following effects can be obtained.

In the present embodiment, as described above, the insulating distance securing element 36 is provided, and the insulating distance securing element 36 is provided between the detection circuit 31 and the ground point for securing the insulation distance between the detection circuit 31 and the ground point. As a result, the insulation distance between the detection circuit 31 and the ground point can be ensured, so that the potential of the detection circuit 31 becomes a potential different from the ground potential. As a result, the insulation distance required between the detection circuit 31 and other devices becomes relatively small, so that other devices can be arranged in the vicinity of the detection circuit 31 . As a result, it is possible to suppress an increase in size of the apparatus due to the inability to arrange another device in the vicinity of the detection circuit 31 for detecting the insulation resistance value.

In addition, in the present embodiment, as described above, the insulation distance securing element 36 includes the chip resistor 60 having the pair of terminals 61 and the resistor body provided between the pair of terminals 61 . Thereby, the insulating distance can be easily secured by utilizing the space (distance L) between the pair of terminals 61 of the chip resistor 60 .

In addition, in the present embodiment, as described above, the insulating distance securing element 36 includes the plurality of chip resistors 60 connected in series with each other. Thereby, even when the insulating distance cannot be sufficiently secured by one chip resistor 60, the insulating distance can be sufficiently secured by the plurality of chip resistors 60 connected in series with each other.

In addition, in the present embodiment, as described above, the plurality of chip resistors 60 are arranged in a linear shape. As a result, the distance between one end and the other end of the plurality of chip resistors 60 connected in series becomes relatively large, unlike a state in which the plurality of chip resistors 60 connected in series are not linear (curved, etc.). , so the insulation distance can be effectively ensured.

In the present embodiment, as described above, the insulating distance securing element 36 , the first resistor 34 and the second resistor 35 are constituted by the same chip resistor 60 . Thereby, compared with the case where the 1st resistor 34, the 2nd resistor 35, and the insulating distance securing element 36 are comprised by mutually different elements, the kind of components which comprise the power conversion apparatus 20 can be reduced.

In addition, in the present embodiment, as described above, the resistance value of the detection resistor 37 is smaller than the resistance value of the first resistor 34 , the second resistor 35 , and the insulation distance securing element 36 including the chip resistor 60 , and the detection circuit 31 It is configured to detect the voltage across the detection resistor 37 . Accordingly, even when the insulation resistance value is relatively small, the detection circuit 31 can easily detect the voltage across both ends of the detection resistor 37 having a relatively small resistance value.

In the present embodiment, as described above, the insulation distance securing element 36 secures the insulation distance between the detection circuit 31 and the ground point so that the potential of the detection circuit 31 with respect to the ground point is electrically suspended. As a result, since the potential of the detection circuit 31 with respect to the ground point is in an electrically floating state, other devices can be arranged in the vicinity of the detection circuit 31 with the insulation distance being substantially zero.

[Variation]

In addition, all points of the embodiment disclosed this time should be considered as illustrative and not restrictive. The scope of the present invention is shown by the claims, not by the description of the above-mentioned embodiment, and the scope of the present invention also includes the meaning equivalent to the claims and all the changes (modifications) within the scope.

For example, in the above-mentioned embodiment, the example in which the insulating distance securing element is constituted by the chip resistor is shown, but the present invention is not limited to this. For example, the insulating distance securing element may be constituted by an element other than a chip resistor such as a diode or a Zener diode.

In addition, in the above-described embodiment, the example in which the insulating distance securing element is constituted by a plurality of chip resistors is shown, but the present invention is not limited to this. For example, if the insulating distance can be sufficiently secured by one chip resistor, the insulating distance securing element may be constituted by one chip resistor.

In addition, in the above-described embodiment, the example in which the plurality of chip resistors are arranged in a straight line is shown, but the present invention is not limited to this. For example, if the insulating distance can be sufficiently ensured, the plurality of chip resistors may be arranged in a shape other than a straight shape such as a curved shape.

In addition, in the above-described embodiment, the example in which the first resistor, the second resistor, and the insulating distance securing element are constituted by the same chip resistor is shown, but the present invention is not limited to this. In the present invention, even if the first resistor, the second resistor, and the insulating distance securing element are formed of different elements (resistors), the insulating distance required between the detection circuit and other devices can be relatively small.

In addition, in the above-mentioned embodiment, the example in which the insulation distance between the detection circuit and the ground point is ensured so that the electric potential of the detection circuit with respect to the ground point is electrically floated is shown, but the present invention is not limited to this. For example, even if the detection circuit is not electrically suspended with respect to the potential of the ground point, the insulation distance required between the detection circuit and other devices can be shortened as long as the potential of the detection circuit is kept away from the potential of the ground point by the insulating distance securing element.

In addition, in the said embodiment, the example which used the solar panel as the "DC power supply" of this invention was shown, but this invention is not limited to this. For example, as the "DC power supply" of the present invention, a DC power supply other than a solar panel such as a wind turbine generator may be used.

Description of reference numerals

10: solar panel (DC power source, power generation unit); 20: power conversion device; 21: DC/AC conversion unit (power conversion unit); 31: detection circuit; 34: first resistor; 35: second resistor; 36: insulation Distance securing element; 37: resistor for detection; 60: chip resistor; 61: terminal; 62: resistor body; 100: power generation system.

Claims (8)

1. A power conversion device is provided with:

a power conversion unit that converts dc power supplied from a dc power supply into ac power;

a detection circuit provided between the dc power supply and the power conversion unit, the detection circuit detecting an insulation resistance value on a positive electrode side and an insulation resistance value on a negative electrode side of the dc power supply; and

and an insulation distance securing element provided between the detection circuit and a ground point for securing an insulation distance between the detection circuit and the ground point.

2. The power conversion device according to claim 1,

the insulation distance securing element includes a chip resistor having a pair of terminals and a resistor body provided between the pair of terminals.

3. The power conversion device according to claim 2,

the insulation distance securing element includes a plurality of the chip resistors connected in series with each other.

4. The power conversion device according to claim 3,

the plurality of chip resistors are arranged in a linear shape.

5. The power conversion device according to any one of claims 2 to 4, further comprising:

a first resistor provided between the detection circuit and a positive electrode side of the dc power supply; and

a second resistor provided between the detection circuit and a negative electrode side of the DC power supply,

the insulation distance securing element, the first resistor, and the second resistor are formed by the same chip resistor.

6. The power conversion device according to claim 5,

further comprising a detection resistor provided between the first resistor and the second resistor and the insulation distance securing element formed by the chip resistor,

the resistance value of the detection resistor is smaller than the resistance values of the first resistor, the second resistor, and the insulation distance securing element formed by the chip resistor,

the detection circuit is configured to detect a voltage across the detection resistor.

7. The power conversion device according to any one of claims 1 to 6,

the insulation distance securing element is configured to secure an insulation distance between the detection circuit and the ground point so that a potential of the detection circuit with respect to the ground point is electrically floating.

8. A power generation system is provided, which comprises a power generation unit,

comprises a power generation unit for generating power by using natural energy, and a power conversion device for converting power supplied from the power generation unit,

the power conversion device includes:

a power conversion unit that converts the dc power supplied from the power generation unit into ac power;

a detection circuit provided between the power generation unit and the power conversion unit, the detection circuit detecting an insulation resistance value on a positive electrode side and an insulation resistance value on a negative electrode side of the power generation unit; and

and an insulation distance securing element provided between the detection circuit and a ground point for securing an insulation distance between the detection circuit and the ground point.

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