JP2001224129A - Generation system and its installation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a generation system which does not generate unnecessary interrupt, at external ground faults. SOLUTION: In a generation system, composed at least of a transformerless inverter and a DC power source having grounding capacity, and connected through a power-receiving ground leakage breaker to a low-voltage distribution system which is connected to a plurality of customers, having ground leakage breakers and has one grounded line, the operating time interval of the power- receiving ground leakage breaker of the generation system is set longer than the operating time intervals of the ground leakage breakers fitted for the group of customers. Or the direction of grounding judging means, which judges whether the position of grounding is inside or outside the generation system, is provided with.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power generation system and a method of installing the same, and more particularly to a power generation system capable of preventing unnecessary operation due to an external ground fault and a method of installing the same.

[0002]

2. Description of the Related Art A photovoltaic power generation system connected to a general low-voltage distribution system will be described with reference to FIG. FIG. 9 is a schematic conceptual diagram showing a conventional photovoltaic power generation system and its connection to a low-voltage distribution system. In the figure, A indicates a consumer having a photovoltaic power generation system, and a photovoltaic power generation system includes a solar cell array 1, a grid-connected inverter 2, and a power leakage breaker 3 for receiving power. Solar array 1 as DC power supply
Is configured by connecting solar cell modules in series and / or parallel so that a desired voltage and current can be obtained. The solar cell array 1 is connected to a system interconnection inverter 2, and the system interconnection inverter 2 is connected to a low-voltage distribution system 4 via a power leakage breaker 3. Further, a load 5 is connected between the system interconnection inverter 2 and the earth leakage breaker 3 for receiving power. DC power from the solar cell array 1 is input to the grid-connected inverter 2, converted into AC power, and output to the load 5 or the low-voltage distribution system 4. The wiring in the customer A is connected to the system interconnection inverter 2 side of the earth leakage breaker 3 for receiving power and the load 5.
Side. The earth leakage circuit breaker 3 for receiving power detects a ground fault accident in the customer A by detecting a ground fault current, so that the influence does not spread to the low voltage distribution system 4 outside the customer A. Disconnect the connection.

In addition, another customer B who does not have a power generation facility
1 and B2 are connected to a low-voltage distribution system 4 via a power leakage breaker 3 for receiving power.

The solar cell array 1 has a floating capacitance 6 to the ground because of its large area. In recent years, as a solar cell module constituting the solar cell array 1, a building material integrated type or a thinned type has been developed.
In some cases, a conductive member (such as a metal plate) is used as a reinforcing material, or a conductive member such as a metal plate is laid as a base material. In such a case, there is a case where the solar cell and the metal plate face each other at a short distance and a large area, and the stray capacitance 6 to the ground increases. In particular, when such a metal plate is grounded, the solar cell or the solar cell module has a stable ground floating capacity.
In addition, if moisture adheres to the surface of the solar cell module due to rain or the like, the ground floating capacitance 6 may be generated via the moisture.

On the other hand, in recent years, in order to increase the efficiency, reduce the size, reduce the weight, and reduce the cost, the grid-connected inverter 2 often employs a so-called transformerless system without an insulating transformer. ing.

[0006]

However, we have found that if a ground fault occurs in another customer B1 or B2 when the stray capacitance 6 to the ground is large and the grid-connected inverter 2 is of a transformerless type, a ground fault current will occur. It has been found that Ig2 intrudes into the system through the ground floating capacitance 6 of the solar cell array 1 and passes through the system interconnection inverter 2, which is detected by the power receiving earth leakage breaker 3 and causes unnecessary operation. When this unnecessary operation occurs in the power receiving circuit breaker 3, the customer A having the photovoltaic power generation system is disconnected from the low-voltage distribution system 4 even though the accident does not necessarily occur in the customer A, and the solar cell is If power is not being generated, the power inside the customer A will be interrupted.

[0007] The above problems are not limited to solar power generation systems. For example, even in a power generation system using a wind power generation system or a fuel cell, a similar problem occurs if the floating capacity to the ground is large, and an external ground fault accident may cause unnecessary operation of the earth leakage breaker for power reception, resulting in a power outage within the customer There is.

An object of the present invention is to solve the above-described problem, and an object of the present invention is to provide a power generation system that can prevent unnecessary operation of a power receiving earth leakage breaker due to an external ground fault.

[0009]

That is, the present invention is connected to a low-voltage power distribution system to which a plurality of consumers each having an earth leakage breaker are connected and one line is grounded, through an earth leakage breaker for receiving power. In a power generation system including at least a transformerless inverter and a DC power supply having a floating capacitance to the ground, the operation time of the earth leakage breaker for power reception of the power generation system is set to be longer than the operation time of the earth leakage breaker provided in the above-mentioned consumer group. The present invention provides a power generation system characterized in that:

Further, the present invention relates to a power generation system which is connected to a low-voltage distribution system in which one line is grounded via a ground leakage circuit breaker for power reception and comprises at least a transformerless inverter and a DC power supply having a floating capacity to ground. There is provided a power generation system having a ground fault direction determining means for determining whether a fault position is inside or outside the power generation system.

Further, the present invention relates to a power generation system which is connected to a low-voltage power distribution system in which one line is grounded via a ground leakage circuit breaker for power reception and comprises at least a transformerless inverter and a DC power supply having a floating capacity to ground. An earth leakage breaker for receiving power is connected to the ground voltage detecting means, the zero-phase current transformer, the zero-phase current detecting means connected to the zero-phase current transformer, and connected to the ground current detecting means and the zero-phase current detecting means. Phase comparing means, a time selector connected to the phase comparing means for selecting a different time period according to a signal output from the phase means, and a zero-phase current level connected to the zero-phase current detecting means. A power generation system comprising: a determination unit; and a contact driving unit connected to the zero-phase current level determination unit and the time selector and driving a contact according to each output. Subjected to.

The present invention also relates to a power generation system which is connected to a low-voltage distribution system in which one line is grounded via a power receiving circuit breaker and comprises at least a transformerless inverter and a DC power supply having a floating capacity to ground. A power receiving earth leakage circuit breaker, a ground voltage detecting means, a ground voltage level determining means connected to the ground voltage detecting means, a zero-phase current transformer, and a zero-phase current detecting means connected to the zero-phase current transformer; A zero-phase current level determining means connected to the zero-phase current detecting means; and a contact driving means connected to the zero-phase current level determining means and the ground voltage level determining means for driving a contact in accordance with respective outputs. And a power generation system.

Further, the present invention relates to a power generation system which is connected to a low-voltage distribution system in which one line is grounded via a power receiving earth leakage breaker and comprises at least a transformerless inverter and a DC power supply having a floating capacity to ground. An earth leakage circuit breaker for receiving power is connected to the ground voltage detecting means, a ground voltage level determining means connected to the ground voltage detecting means, and a time limit is connected to the ground voltage level determining means and a time limit is set according to an output of the ground voltage determining means. A time selector to be selected; a zero-phase current transformer; zero-phase current detection means connected to the zero-phase current transformer; zero-phase current level determination means connected to the zero-phase current detection means; A power generation system comprising: a phase current level determining means; and a contact driving means connected to the time selector and driving a contact according to each output.

The present invention also relates to a power generation system comprising at least a transformerless inverter and a DC power supply having a floating capacity to the ground in a low-voltage distribution system to which a plurality of customers each having an earth leakage breaker are connected and one line is grounded. In the installation method of the power generation system connecting the system via the power receiving circuit breaker, as the power receiving circuit breaker, the operation time is set to be longer than the operation time of the circuit breaker provided in the customer group. Provided is a method for installing a power generation system, characterized by connecting an earth leakage breaker.

Further, the present invention provides a power generation system comprising at least a transformerless inverter and a DC power supply having a floating capacity to the ground in a low-voltage distribution system in which one line is grounded.
A method of installing a power generation system connected via a power leakage breaker for receiving power, the method comprising: installing a ground fault direction determining means for determining whether a ground fault position is inside or outside the power generation system. provide.

The power generation system of the present invention is preferably connected to a low-voltage distribution system composed of a single-phase low-voltage distribution system and a three-phase distribution system that are commonly grounded.

In a preferred aspect of the power generation system according to the present invention, when the ground fault direction determining means determines that the ground fault position is inside, the time required for the power receiving circuit breaker to operate is equal to the ground fault. When the direction determining means determines that the ground fault position is outside, a mode shorter than the time until the power receiving earth leakage breaker operates, and when the ground fault direction determining means determines that the ground fault position is internal. The power receiving earth leakage breaker operates when the ground fault direction determining means determines that the ground fault position is outside, and the power receiving earth leakage breaker does not operate.

It is preferable that the ground fault direction determining means determines whether the ground fault position is inside or outside based on the phase difference between the ground voltage and the zero-phase current of the ground terminal of the low-voltage distribution system. Also,
If the transformerless inverter is connected to a single-phase distribution system, the ground fault position is determined to be external when the ground voltage of the ground terminal of the single-phase distribution system is higher than a normal value in the single-phase distribution system. The ground fault direction determining means is also preferably used.

The DC power source preferably includes a solar cell, particularly preferably the solar cell has a solar cell element and a metal plate, and more preferably the metal plate is grounded. A DC power supply composed of a solar cell array in which a plurality of solar cells are connected in series and / or in parallel is also suitably used in the present invention.

The above preferred embodiments are the same for the installation method of the present invention.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) In this embodiment,
A system in which the operation time limit of the power receiving earth leakage breaker on the power generation system side is set later than the operation time limit of the power receiving earth leakage breaker of another customer group connected to the same low-voltage distribution system will be described. The feature of this embodiment is that it achieves the purpose of the present invention very simply, inexpensively and substantially.

In most cases, a customer other than a customer having a power generation system is also provided with a power receiving circuit breaker (hereinafter simply referred to as a circuit breaker), and a ground fault accident occurs inside the customer. In this case, the earth leakage breaker operates at an appropriate speed (often within 0.1 second), and the power supply from the low-voltage distribution system to the customer is cut off. At that time, the essential technology of the present embodiment is to prevent the leakage breaker of the customer having the power generation system from operating for a certain period of time to prevent the interruption caused by the leakage in the other customers. It is an idea. Hereinafter, a specific description will be given.

FIG. 1 shows a power generation system according to this embodiment.
This will be described with reference to FIG. FIG. 1 is a schematic conceptual diagram showing a preferred example of a power generation system according to the present embodiment and its connection to a low-voltage distribution system.

(DC Power Supply) The DC power supply of the power generation system of the present invention is not particularly limited as long as it has a floating capacity to the ground. As described later, a power supply including a solar cell is suitable as the DC power supply.

(Solar Cell Array) A solar cell array 1 suitably used as a DC power supply of the power generation system of the present invention.
Can have various configurations. Of course, instead of an array, one solar cell can be used as a DC power supply, but a solar cell array having a plurality of solar cells is suitable for obtaining large power. The solar cell array 1 only needs to have a ground floating capacitance 6,
The type of the solar cell module constituting the array is not limited. The effect of the present invention is greater as the ground floating capacitance 6 is larger, a solar cell module in which solar cells (elements) are resin-sealed on a metal reinforcing plate, a solar cell module constructed to be in contact with the metal plate, The present invention is particularly effective when a solar cell array is formed by building material integrated solar cell modules and the like. In addition, the effect of the present invention can be obtained even when a solar cell array using a solar cell module in which the floating capacitance 6 to the ground becomes large due to rain or the like even when the floating capacitance 6 to the ground is small normally. In addition, when the metal reinforcing plate, the metal plate, and the like are grounded, since there is a stable floating capacitance to the ground, unnecessary interruption is likely to occur, and the effect of the present invention is remarkably exhibited. become. The range of the stray capacitance to the ground where the effect of the present invention is particularly remarkable is 0.1 μF
That is all. (In principle, the larger the capacity, the more easily the leakage current flows, so there is no upper limit.) In this embodiment, a solar cell module having a metal plate on the back surface (manufactured by Canon, product type BS2-01, rated output 60 Wp (Watt peak)), and a 3.6 kWp array was constructed using 60 sheets (15 in series and 4 in parallel). All the back metal plates were grounded. The measured value of the floating capacitance 6 at this time was 2.4 μF. Note that, in principle, the capacity 6
This naturally includes the capacity of a filter capacitor or the like inside the inverter. The point is that the capacitance of the DC circuit with respect to the ground becomes a problem.

(Inverter) The inverter 2 is a transformerless inverter, and various transformerless inverters can be used. The present invention has been made by focusing on the fact that intrusion of an external ground fault current occurs in a power generation system combining a non-insulated type inverter and a DC power supply having a stray capacitance. In order for such a situation to occur, a transformerless inverter is essential. In the present embodiment, a transformerless inverter (model LINEBACK FX) manufactured by Nippon Battery was used. In addition, it is desirable that the output electric system (single-phase / three-phase, voltage, frequency) of the inverter is adjusted to the distribution system to be interconnected.

(Low-voltage distribution system) The low-voltage distribution system 4 may be a low-voltage distribution system in which one line is grounded, and there is no limitation on voltage, frequency, and wiring system. In the present embodiment, a single-phase three-wire 100 V / 200 V, 60 Hz power distribution system is used.

(Load) The load 5 may be anything as long as it consumes power, for example, a general electric appliance. In the present embodiment, an electric stove of 1 kW is used as the load 5 and installed in the consumers A, B1, and B2.

(Electric Leakage Circuit Breaker for Power Receiving) As the earth leakage circuit breaker 3A used in the power generation system, one incorporating the operation time setting means 7 was adopted. There are many commercially available earth leakage breakers of this type, which can be used. The operating current is 30 mA. Needless to say, the operation time limit setting means 7 may be externally provided, and various known techniques may be applied to the operation time limit setting method irrespective of digital or analog.

In this embodiment, another customer group B
1, the rated operating current 30m as the earth leakage breaker 3 of B2
A, those with an operation time limit of 0.1 second or less were selected. The reason for the selection is that the earth leakage breaker of this degree of sensitivity and operating current is most frequently used in ordinary households.

The essential technical idea of the present embodiment is that the leakage breaker of the customer having the power generation system is not operated for a certain period of time to prevent the interruption caused by the leakage in the other customers. Things. Therefore, the operation time of the earth leakage breaker 3A of the power generation system is set to 0.8 seconds, which is longer than the operation time of the earth leakage breakers 3 of the other customer groups B1 and B2. It is desirable that the operation time limit of the earth leakage breaker 3A is short as long as the object of the present invention can be achieved. More specifically,
It is preferable that the time be 0.1 second or more and 1.0 second or less.

To change the time period, there is a method of changing the rated operating current in addition to directly changing the delay time period. This method utilizes the fact that a leakage breaker with a large rated operating current (the one with lower sensitivity) operates slowly when a leakage current of the same magnitude flows. That is, the earth leakage breaker 3 on the power generation system side
The rated operating current of A is connected to the earth leakage breakers 3 of the customer groups B1 and B2.
May be set to a value larger than the rated operating current, but it is preferable to consider that extreme reduction in sensitivity should not be caused. Specifically, the rated operating current of the earth leakage breaker 3A is preferably 100 mA or more and 1000 mA or less.

When a system is constructed using a commercially available earth leakage breaker, a method of directly changing the delay time is preferable to a method of changing the rated operating current because the condition can be easily set.

(Operation Test) In the customer B2, a ground fault having a leakage current of 500 mA for 0.1 second was generated. B2
The circuit breaker of No. 1 operated in about 50 ms, and the circuit breaker of B1 did not operate because there was no leakage current intrusion. In addition, although the leakage current leaking into the power generation system at this time reached almost 200 mA, it was confirmed that the leakage breaker 3A itself did not operate, and unnecessary breakage did not occur.

(Second Embodiment) In this embodiment,
A system using a ground fault direction determining means for determining whether or not a ground fault has occurred in the ground fault detection function on the power generation system side will be described.

As shown in FIG. 9, which is a conventional example, the ground fault current Ig2 enters the power generation system A through the ground floating capacitance 6. The pseudo equivalent circuit at this time is shown in FIG. Ground fault current Ig0 generated by ground fault resistance Rx of customer B2
Means that the current Ig1 flowing through the B-class grounding resistor Rb, which should flow normally, and the series circuit of the D-class grounding resistor Rd and the stray capacitance C to the ground (when the back metal plate of the solar cell module is D-class grounded) Current Ig2. Therefore, in this case, when the ground potential of the neutral wire is set to the reference phase, the zero-phase current (intrusion ground fault current Ig2) flowing through the power generation system becomes a leading current. In this embodiment, by detecting the intrusion ground fault current Ig2 by utilizing this fact, it is determined whether the ground fault has occurred outside or inside the customer A and the operation of the circuit breaker is controlled. It is a big feature of.

FIG. 2 is a schematic conceptual diagram showing a preferred example of a power generation system according to the present embodiment and its connection to a low-voltage distribution system. In FIG. 2, A is a customer having a photovoltaic power generation system, and the earth leakage breaker 3B in the power generation system has a ground fault direction determining means 8A. In FIG.
The solar cell array 1, the grid-connected inverter 2, the low-voltage distribution system 4, the load 5, and the earth leakage breaker 3 used for the customer groups B1 and B2 are the same as those in the first embodiment.

(Structure of Circuit Breaker 3B) The earth leakage breaker 3B used in the present embodiment includes a ground fault direction determining means 8A. The ground fault direction determining means 8A may be included in the earth leakage breaker 3B as shown in FIG. 2, or may be provided separately from the earth leakage breaker 3B. Earth leakage breaker 3B
Is shown in FIG. FIG. 3 is a schematic block diagram showing the configuration of the earth leakage breaker 3B.

The ground fault direction determining means 8A includes a ground voltage detecting means 82, a zero-phase current transformer 81, and a zero-phase current detecting means 8
3. It comprises a phase comparing means 84. Ground fault direction determining means 8A
Is determined that a ground fault has occurred outside the customer A (external ground fault) when the phase of the ground voltage based on the zero-sequence current falls within a certain phase range, and , The ground fault has occurred inside the customer A (internal ground fault), and the result is output. In this example, from -30 degrees to -150 degrees (-
It is determined that an external ground fault has occurred when the vehicle enters an area up to 90 ° ± 60 °). In the case of this example, since the intrusion route has a stable stray capacitance, the range for determining an external ground fault is narrower around −90 degrees (for example, 90 degrees).
(± 30 degrees). A variety of voltage detectors, current detectors, phase comparators, and the like that can be used for such purposes are commercially available as signal converters, and known and publicly available technologies can be used.

The judgment result (judgment output) output from the phase comparing means 84 is sent to the time limit selector 32 to select a time limit. Specifically, when it is determined that an external ground fault has occurred, 0.8 second is selected, and when it is determined that an internal ground fault has occurred, 0.1 second is selected.

The result of the time period selection is sent to the contact driving means 33 together with the result of the zero-phase current level judging means 31 (judgment level 30 mA), and the contact 34 is operated.

(Operation test) As in the first embodiment, 5
When a ground fault of 00 mA and 0.1 second was generated at the customer B2, it was confirmed that unnecessary shutoff of the power generation system did not occur. Furthermore, in the present embodiment, the operation time limit at the time of external determination is set to infinity, that is, non-operation, so that the power generation system can be shut down even if there is a ground fault in the mains of the distribution system 4 that is not protected from ground fault. Can be suppressed. However, it is necessary to consider the necessity of disabling in consideration of the necessity of system safety and the like.

Further, the earth leakage circuit breaker for power reception according to the present embodiment enables highly accurate inside / outside judgment, and does not reduce the response speed in case of an internal ground fault. In other words,
When an internal ground fault occurs, the operation is exactly the same as that of a normal earth leakage breaker for power reception, so that the safety is very high.

(Third Embodiment) In the present embodiment,
The case where the low-voltage distribution system is composed of a single-phase system and a three-phase system that are commonly grounded (including an irregular V connection, etc.) will be described. Such systems are most susceptible to external ground faults. This is particularly noticeable when the power generation system is connected to a single-phase system. First, the reason will be described with reference to the drawings. For example, as shown in FIG. 4, an example of a vector diagram when a three-phase system of Δ connection and a single-phase three-wire system are commonly grounded is as shown in FIG. When a ground fault occurs in the S phase (S line), a larger ground potential than when a ground fault occurs in the R phase or the T phase of the single phase system. (N line) and the ground. Therefore, the zero-phase current also increases. That is, the ground fault current that enters the power generation system increases, and the unnecessary operation of the earth leakage breaker tends to occur. According to the present invention, a greater effect can be expected when interconnected to a low-voltage distribution system having such a common ground line. It should be noted that such an example of the common grounding is considered to be peculiar to the power generation system linked to the low-voltage distribution system.

With respect to such a system, a simpler means than the second embodiment can be used as the ground fault direction determining means. Hereinafter, this embodiment will be specifically described with reference to FIG.

In FIG. 4, the solar cell array 1, the inverter 2, the load 5, and the power receiving earth leakage breakers 3 of the customers B1 and B2 have the same configuration as that of the first embodiment. Regarding other points, the description of the same points as those in the second embodiment is omitted.

(Low-voltage distribution system 4) Here, as shown in FIG. 4, a system for commonly distributing a single-phase three-wire system and a three-phase system from a three-phase transformer was used as a low-voltage distribution system. Besides this,
Two systems having a common ground point, for example, a system having individual transformers as shown in FIG.
An irregular V-connection using a combination of the two can also be applied to the present embodiment.

(Blocking Means 3C) The direction determining means 8B, which is simpler than the second embodiment, can be used for the circuit breaker 3C used in the present embodiment. Such a circuit breaker 3
FIG. 5 shows an outline of C and the direction determination means 8B. In the example of FIG. 5, specifically, the output level of the ground voltage detecting means 82 is determined by the ground voltage level determining means 85, and the result is determined. That is, in the present embodiment, the neutral line (N line)
Only the ground voltage of the above is determined to determine whether it is an external ground fault or an internal ground fault. More specifically, the determining unit 85 determines that the output of the ground voltage detecting unit 82 is lower than a preset voltage threshold value as an internal ground fault, and determines that the output is higher than the preset voltage threshold value. Then, the judgment output is sent to the time period selector 32 to select the time period. The result of the time period selection is sent to the contact driving means 33 together with the result of the zero-phase current level judging means 31 to operate the contact. It is convenient to set the voltage threshold value so as to determine that an external ground fault has occurred when a voltage higher than the system voltage to which the power generation system is connected is detected. The worst-case ground fault (ground fault that causes the highest ground voltage) actually occurs inside the power generation system, and the voltage threshold is set based on the ground potential at that time. Since it can be lower, it is more preferable from the viewpoint of power generation system protection. In the present embodiment, the fluctuation of the commercial system voltage is also considered,
The voltage threshold was set at 110V.

In the second embodiment, the direction is determined by comparing the phases, but in the present embodiment, the determination is performed by detecting the voltage. Therefore, there is a feature that the configuration is simplified and the cost is advantageous.

Elements other than the direction determination are the same as those in the second embodiment, so that the description is partially omitted.

(Operation test) A ground fault (5
(00 mA, 0.1 second), the ground potential rose to 130 V, and it was confirmed that unnecessary interruption (unnecessary operation of the earth leakage breaker) did not occur. However, when an R-phase or T-phase ground fault common to the single-phase power distribution system is generated, unnecessary interruption occurs. This is because the ground potential does not rise to 110 V when an S-phase or T-phase ground fault is generated. Such an unnecessary cutoff is performed by the time selector 3.
2 can be prevented by delaying the operation time limit of the earth leakage breaker 3C in the same manner as in the second embodiment.

As shown in FIG. 7, the most suitable system for performing the direction judgment with respect to the ground voltage as in the present embodiment is that the single-phase system and the three-phase system have separate transformers and one line is shared. This is the case when it is grounded. In the case shown in FIG. 7, unlike the case shown in FIG. 4, a ground potential rise also occurs when an R-phase or T-phase ground fault occurs, and it is possible to determine whether an internal ground fault or an external ground fault is occurring. . That is, in the case shown in FIG. 7, the time selector 32 becomes unnecessary. In the case shown in FIG. 7, since the neutral S and N phases are originally grounded, it is not generally necessary to detect a ground fault in these phases.

[0054]

As described above, the present invention has the following remarkable effects. (1) Unnecessary shutoff operation is not performed in the event of an external ground fault. This reduces power outages in the power generation system. (2) Since the number of power outages is reduced, the chance of stopping power generation is also reduced, and power generation loss is hardly caused.

[Brief description of the drawings]

FIG. 1 is a schematic conceptual diagram showing a preferred example of a power generation system according to a first embodiment of the present invention and its connection to a low-voltage distribution system.

FIG. 2 is a schematic conceptual diagram showing a preferred example of a power generation system and a connection to a low-voltage distribution system according to a second embodiment of the present invention.

FIG. 3 is a schematic conceptual diagram showing an example of a configuration of an earth leakage breaker used in the present invention.

FIG. 4 is a schematic conceptual diagram showing a preferred example of a power generation system according to a third embodiment of the present invention and its connection to a low-voltage distribution system.

FIG. 5 is a schematic conceptual diagram showing an example of a configuration of an earth leakage breaker used in the present invention.

FIG. 6 is an example of a voltage vector diagram of a common ground system.

FIG. 7 is a schematic conceptual diagram showing an example of a common grounding system that can be connected to a power generation system according to a third embodiment of the present invention.

FIG. 8 is a conceptual diagram illustrating a pseudo-equivalent circuit showing a generation path of an inrush ground current.

FIG. 9 is a schematic conceptual diagram showing an example of a conventional power generation system and its connection to a low-voltage distribution system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Solar cell array (DC power supply) 2 Grid connection inverter (Transformerless inverter) 3 Earth leakage breaker for receiving power 3A Earth leakage breaker with operation time delay 3B, 3C Earth leakage direction judgment function earth leakage direction breaker 4 Low voltage distribution system 5 Load 6 Stray capacitance to ground 7 Operation time limit setting means (delay means) 8A, 8B Ground fault direction determining means 31 Zero-phase current level determining means 32 Time limit selector 33 Contact driving means 34 Load switching contact 81 Zero-phase current transformer 82 Ground voltage detection Means 83 Zero-phase current detecting means 84 Phase comparing means 85 Ground voltage level determining means A Consumers having a photovoltaic power generation system B1, B2 Consumers having no power generation facilities Ig0 Ground fault current Ig1 Distribution system grounding pole (Class B grounding) ) Ground fault current flowing into the Ig2 power generation system

Claims (24)

[Claims] 1. A low-voltage distribution system to which a plurality of consumers each having an earth leakage breaker are connected and one line is grounded is connected via an earth leakage breaker for power reception to connect at least a transformerless inverter and a stray ground to ground. In the power generation system comprising a DC power supply, the operation time limit of the earth leakage breaker for power reception of the power generation system is set to be longer than the operation time period of the earth leakage breaker provided in the customer group. . 2. The power generation system according to claim 1, wherein the low-voltage distribution system is a low-voltage distribution system including a single-phase low-voltage distribution system and a three-phase distribution system that are commonly grounded. 3. A power generation system connected to a low-voltage power distribution system in which one line is grounded via a ground fault circuit breaker for power reception and comprising at least a transformerless inverter and a DC power supply having a floating capacity to ground. A power generation system comprising: a ground fault direction determination unit that determines whether the power generation system is inside or outside. 4. When the ground fault direction determining means determines that the ground fault position is inside, the time until the power receiving earth leakage breaker operates is determined by the ground fault direction determining means determining that the ground fault position is outside. 4. The power generation system according to claim 3, wherein the time is shorter than the time required for the power receiving circuit breaker to operate. 5. When the ground fault direction determining means determines that the ground fault position is inside, the power receiving earth leakage breaker operates, and when the ground fault direction determining means determines that the ground fault position is outside. 4. The power generation system according to claim 3, wherein the power leakage breaker does not operate. 6. The power generation system according to claim 3, wherein the low-voltage distribution system is a low-voltage distribution system configured by a single-phase low-voltage distribution system and a three-phase distribution system that are commonly grounded. 7. A ground fault direction determining means for determining whether a ground fault position is inside or outside based on a phase difference between a ground voltage and a zero-phase current of a ground terminal of a low-voltage distribution system. Item 7. The power generation system according to any one of Items 3 to 6. 8. The single-phase distribution system, wherein the transformerless inverter is connected to a single-phase distribution system, and the ground fault direction determining means determines that a ground voltage of a ground terminal of the single-phase distribution system is higher than a normal value in the single-phase distribution system. The power generation system according to claim 6, wherein the ground fault position is determined to be outside when the ground fault is high. 9. The DC power source includes a solar cell.
9. The power generation system according to any one of items 1 to 8. 10. The power generation system according to claim 9, wherein the solar cell is a solar cell module having a solar cell element and a metal plate. 11. The apparatus according to claim 1, wherein the metal plate is grounded.
0. The power generation system according to 0. 12. The power generation system according to claim 9, wherein the DC power supply comprises a solar cell array in which a plurality of solar cells are connected in series and / or in parallel. 13. A power generating system connected to a low-voltage power distribution system in which one line is grounded through a power leakage breaker for power reception and comprising at least a transformerless inverter and a DC power supply having a floating capacity to ground, A zero-phase current transformer, a zero-phase current detector connected to the zero-phase current transformer, and a phase comparator connected to the ground current detector and the zero-phase current detector. Means, and a time selector which is connected to the phase comparing means and selects a different time according to a signal output from the phase means,
Zero-phase current level determination means connected to the zero-phase current detection means, contact drive means connected to the zero-phase current level determination means and the time selector and driving contacts according to respective outputs, A power generation system comprising: 14. A power receiving system connected to a low-voltage power distribution system in which one line is grounded via a power leakage breaker for power reception and comprising at least a transformerless inverter and a DC power supply having a floating capacity to ground, A ground voltage detecting means, a ground voltage level determining means connected to the ground voltage detecting means, a zero-phase current transformer; a zero-phase current detecting means connected to the zero-phase current transformer; Zero-phase current level determining means connected to the phase current detecting means, and contact driving means connected to the zero-phase current level determining means and the ground voltage level determining means and driving a contact according to each output, A power generation system comprising: 15. A power supply system connected to a low-voltage power distribution system in which one line is grounded via a power leakage breaker for power reception and comprising at least a transformerless inverter and a DC power supply having a floating capacity to ground, A ground voltage detecting means, a ground voltage level determining means connected to the ground voltage detecting means, and a time selection connected to the ground voltage level determining means and selecting a time period according to an output of the ground voltage determining means A zero-phase current transformer; zero-phase current detection means connected to the zero-phase current transformer; zero-phase current level determination means connected to the zero-phase current detection means;
A power generation system comprising: a contact driving means connected to the zero-phase current level determining means and the time selector for driving a contact according to each output. 16. A power generation system comprising at least a transformerless inverter and a DC power supply having a ground floating capacity is connected to a low-voltage distribution system to which a plurality of consumers each having an earth leakage breaker are connected and one wire is grounded. In the installation method of the power generation system connected via the earth leakage breaker, as the earth leakage breaker for receiving, an earth leakage breaker whose operation time is set to be longer than an operation time of the earth leakage breaker provided in the customer group is used. A method for installing a power generation system, characterized by connecting. 17. A method of installing a power generation system in which a power generation system including at least a transformerless inverter and a DC power supply having a floating capacity to ground is connected to a low-voltage distribution system in which one line is grounded via a power leakage breaker for receiving power. At
A method for installing a power generation system, comprising: a ground fault direction determining means for determining whether a ground fault position is inside or outside the power generation system. 18. The ground fault direction determining means determines that the ground fault position is outside when the ground fault direction determining means determines that the ground fault position is internal, until the power receiving earth leakage breaker operates. 18. The method according to claim 17, wherein a control unit is provided so as to be shorter than the time required for the power receiving circuit breaker to operate when the power receiving system is operated. 19. When the ground fault direction determining means determines that the ground fault position is inside, the power receiving earth leakage breaker is operated, and when the ground fault direction determining means determines that the ground fault position is outside. 18. The method according to claim 17, further comprising: providing a control unit that does not operate the earth leakage breaker for power reception. 20. As the ground fault direction determining means, a ground fault direction determining means for determining whether a ground fault position is inside or outside from a phase difference between a ground voltage and a zero-phase current of a ground terminal of a low-voltage distribution system is used. The method for installing a power generation system according to claim 17, wherein: 21. The method according to claim 15, wherein a power supply including a solar cell is provided as the DC power supply. 22. The method according to claim 21, wherein a solar cell module having a solar cell element and a metal plate is used as the solar cell. 23. The method according to claim 22, further comprising a step of grounding the metal plate. 24. The method according to claim 21, wherein a solar cell array in which a plurality of solar cells are connected in series and / or in parallel is provided as the DC power supply.