JP2000358330A - Photovoltaic power generating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To parallel off distributed power supplies at two points by providing a controller with a parallel-off control means, which transmits an open command for switches for parallel-off based on detection of a single operation of the distributed power supplies at times of system troubles. SOLUTION: N number of distributed power supplies #1 to #n 14 are provided with a solar cell 15 and a power conversion section 16, and the power conversion sections 16 are formed of inverters 17 as inversion devices. The inverters 17 are small-capacitance inverters and provided on the alternating-current output side with a first switch 18 for parallel-off. A first parallel-off point is formed at the switch 18. A second switch 19 for parallel-off, which forms a second parallel-off point, is installed in series with the first switch 19 for parallel-off, and the inverters 17 of the distributed power supplies 14 are connected with a power system 1 via the switches 18 and 19 for parallel-off. Thus the distributed power supplies 14 can be paralleled off from the power system 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic power generator in which a plurality of distributed power sources of solar cells are connected to an electric power system, and the operation of these distributed power sources is centrally controlled by a single controller. Specifically, it relates to the disconnection of each distributed power supply at the time of the system abnormality.

[0002]

2. Description of the Related Art Conventionally, in the field of photovoltaic power generators, for example, the applicant already filed an application (Japanese Patent Application No. 8-327851).
No.), the factory,
If large-scale, large-power, large-scale solar cells cannot be installed on a roof or a side wall of a building or a general house, the large-scale solar cells are replaced with a plurality of small-scale, small-sized solar cells. A plurality of distributed power supplies having a solar cell configuration in which a battery and a small-sized and small-capacity inverter serving as a stationary inverse converter are combined are distributed and installed on the roof or the side wall.

[0003] A conventional photovoltaic power generator having a plurality of distributed power supply configurations is formed substantially as shown in FIG.

FIG. 2 shows that power system 1 has # 1, # 2,.
This shows a case where n distributed power supplies 2 are interconnected, and each distributed power supply 2 is composed of a solar cell 3 of about several KW and a power generated by, for example, an inverter 4 of 10 KW as a stationary inverse converter. And a conversion unit 5.

[0005] The inverter 4 of each distributed power source 2 is provided with a disconnecting switch 6 composed of an internal contactor or the like on the AC output side (system side), and is connected to the power system 1 via the switch 6. Connected.

Further, a common system interconnection protection device 8 for each distributed power source 2 is provided between each distributed power source 2 and a system power source 7 such as a substation of the power system 1. Is based on the detection result of the system voltage of the system interconnection protection relay 9, etc.
The common control device 10 of each distributed power supply 2 monitors and detects whether there is a system abnormality such as a system power failure.

The control device 10 transmits a drive control signal of the inverter 4 to each of the distributed power sources 2 by wire communication or wireless communication via the communication line 11 to centrally control the operation of each of the distributed power sources 2. When the system is normal, the inverters 4 of the respective distributed power sources 2 are connected to each other in synchronization with the system voltage.

By the way, in this type of photovoltaic power generation system, a so-called photovoltaic power generation system guideline (system interconnection) is used in order to prevent the individual operation of each distributed power source 2 when a system failure such as a system power failure occurs. It is necessary to provide two disconnection points for each distributed power source 2 based on the standard of the technical requirement guideline).

Then, the disconnecting switch 6 of each distributed power source 2
Form a first disconnection point, a common disconnection switch 12 that forms a second disconnection point is conventionally provided in the grid interconnection protection device 8, and each distributed power supply 2 Are connected to the system power supply 7 via the respective disconnecting switches 6 and the common disconnecting switch 12.

Further, according to the standard of the guideline, it is desirable that the independent operation of each distributed power source 2 is detected and prevented by a combination of an active system and a passive system.

For this reason, the control device 10 transmits an opening command of the respective disconnecting switches 6 to the respective distributed power sources 2 through the control line 11 by detecting the active type of isolated operation, and these disconnecting switches 6 At the same time, the switch 6 is opened, and an open command is transmitted to the disconnecting switch 12 via the internal control line 13 by detecting the passive operation of the passive type, and the disconnecting switch 12 is opened.

In the active mode of islanding detection, the frequency, active power or reactive power of the AC output of the inverter 4 of each distributed power source 2 is forcibly and periodically fluctuated, and each distributed power source 2 is wired or wirelessly. It monitors sudden changes in the voltage, current or frequency of the AC output of each inverter transmitted from the inverter and detects a transition from those sudden changes to islanding operation.

The passive operation detection of the passive type is to monitor the phase, the third harmonic or the frequency of the system voltage, and to detect a transition from the rapid change to the single operation.

When a system abnormality occurs, the disconnecting switch 6 of each distributed power supply 2 is opened based on the detection of the transition to the islanding operation, and the disconnecting switch 12 of the system interconnection protection device 8 is opened. By one or both, each distributed power source 2 is disconnected from the power system 1.

At this time, the inverter 4 of each distributed power source 2
The connection of the AC output side is switched to an emergency load (important load), not shown, and the operation mode is switched to the independent operation by the control device 10.

During a system power outage or the like, the independent operation output of each distributed power source 2 is supplied to an emergency load separated from the power system 1.

[0017]

In the case of the conventional device shown in FIG. 2, the second disconnection point of each distributed power supply 2 is formed by a common disconnection switch 12 provided in the system interconnection protection device 8. Therefore, depending on the capacity and the number of each distributed power source 2, it is necessary to provide an extremely large capacity and large switch inside the panel of the grid connection protection device 8 as the disconnecting switch 12.

In this case, there is a problem that not only the disconnecting switch 12 becomes large and expensive, but also the size of the system interconnection protection device 8 becomes large and this device 8 becomes large and expensive.

When the distributed power supply 2 is added, etc.,
At the same time, the capacity of the disconnecting switch 12 of the system interconnection protection device 8 must be increased, and in some cases, there is a problem that the panel of the system interconnection protection device 8 needs to be replaced or added.

Further, since the size of the system interconnection protection device 8 varies depending on the capacity and the number of the distributed power sources 2, the overall size of the system cannot be unified to improve productivity and reduce costs. There is also.

In addition, since the power cable on the AC output side of each distributed power supply 2 must be led into the system interconnection protection device 8, there is also a problem that the degree of freedom in panel arrangement and the like is limited. .

According to the present invention, when centrally controlling the operation of a plurality of distributed power supplies having a solar cell configuration by a common control device, the size of the grid connection protection device can be increased regardless of the capacity and the number of distributed power supplies. Without limiting the degree of freedom of board layout,
It is an object of the present invention to allow each distributed power supply to be disconnected at two points.

[0023]

In order to solve the above-mentioned problems, in a photovoltaic power generator according to the present invention, an internal contact or the like of the inverter is provided on the system side of the inverter in each of the distributed power sources. A first disconnection switch forming a first disconnection point and a second disconnection switch forming a second disconnection point are provided in series. Disconnection control means is provided for transmitting an open command for each of the two disconnection switches to each distributed power supply upon detection of isolated operation of each distributed power supply at the time of abnormality.

Accordingly, each of the distributed power supplies is provided with a disconnecting switch at the first and second disconnection points, and when the system is abnormal, these switches are transmitted from the common control device. Opened by the open command, each distributed power source is disconnected from the power system.

In this case, each of the distributed power supplies has two parallel disconnection points individually formed by the two parallel disconnection switches.

These off-switches are formed of small-capacity, small-sized switches corresponding to the capacity of each distributed power supply, regardless of the number of distributed power supplies.

Moreover, the large common disconnecting switch of the conventional system interconnection protection device is omitted.

Therefore, regardless of the capacity and the number of distributed power supplies, each distributed power supply has a small capacity without providing a large-capacity large disconnection switch in a system interconnection protection device or the like. It can be formed by providing two off-switches of small capacity and small size, each panel size does not increase, the capacity of the grid connection protection device etc. is increased by the addition of the distributed power supply, the replacement of the panel, There is no need for additional installation, and it is not necessary to lead the power cables of each distributed power supply to the system interconnection protection device, and the degree of freedom in panel layout is not limited.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, n distributed power supplies 14 of # 1 to #n each include a small-sized and small-sized solar cell 15 of several KW similar to the solar cell 3 of FIG. The power converter 16 is formed by an inverter 17 as a stationary type reverse converter.

The inverter 17 corresponds to the conventional inverter 4 shown in FIG. 2 and is a relatively small-capacity inverter of, for example, 10 kW, and its AC output side (system side) has a disconnecting switch 6 shown in FIG. Is provided with a first disconnecting switch 18 such as an internal contactor corresponding to
Is formed.

Further, a second disconnection switch 19 for forming a second disconnection point in series with the first disconnection switch 18 is provided, and the inverter 17 of each distributed power supply 14 has its own inverter. It is connected to the electric power system 1 via the disconnecting switches 18 and 19.

At this time, the two paralleling switches 18 and 19 are
Each of the distributed power supplies 14 includes a switch having a capacity and a size corresponding to the inverter 17.
2 is 1 / n smaller in capacity and smaller than the disconnecting switch 12 of FIG. 2, and does not increase in size even if the number of distributed power supplies 14 increases.

On the other hand, the system interconnection protection device 20 is, for example, shown in FIG.
In this configuration, the common disconnecting switch 12 is omitted from the device 8, and the common control device 22 performs wired communication via the communication line 23 based on the detection result of the system voltage of the system interconnection protection relay 21 and the like. Alternatively, the operation of the inverter 17 of each distributed power supply 14 and the opening and closing of both paralleling switches 18 and 19 are controlled by wireless communication.

At this time, since the system interconnection protection device 20 does not have the large disconnecting switch 12 shown in FIG. 2, the panel size is small and small irrespective of the capacity and number of the distributed power sources 14. .

When the system power supply 7 is normal (when the system is normal), a control command for interconnection operation is transmitted from the control device 22 to each distributed power supply 14, and the inverter 17 of each distributed power supply 14 Is synchronized with the operation.

In addition, when the system is abnormal, based on the detection of the active operation and the passive operation in the same manner as the control device 10 shown in FIG.
Then, for example, by changing the control code, the two parallel disconnecting switches 18, 1
9 Each open command is transmitted.

Then, these release commands are received (received).
, The disconnecting switches 18, 19 of each distributed power source 14
Is released, and each distributed power supply 14
Is disconnected from the power system 1.

At this time, the AC output side of the inverter 17 of each distributed power source 14 is connected to a common emergency load via, for example, an emergency power supply switch (not shown), and is controlled by the control device 22 to operate independently. In addition, the independent operation output of each distributed power supply 14 is supplied to the emergency load.

Then, when the system returns to normal, each distributed power supply 14 is disconnected from the emergency load, and the disconnecting switches 18 and 19 are disconnected.
Is closed, and the operation is returned to the interconnection operation.

In this case, each distributed power source 14 is formed in the same panel size by providing small capacity and small disconnecting switches 18 and 19 corresponding to the respective capacities. Conventional large-capacity, large-sized common disconnecting switch 1
2 are not provided, and the size is small irrespective of the capacity and the number of distributed power supplies 14.

Therefore, even if the number of distributed power supplies 14 increases, the panel size of the system interconnection protection device 20 and the like does not increase, and the size does not increase.

When the distributed power supply 14 is added, the capacity of the system interconnection protection device 20 or the like is not required to be increased, and it is not necessary to replace or add them.

Since the board sizes of the distributed power supply 14, the system interconnection protection device 20, and the like do not change depending on the number of the distributed power supplies 14, the board sizes are unified and standardized.
It is possible to improve productivity and reduce costs.

Further, since the power cables of the respective distributed power sources 14 are directly connected to the power system 1 and there is no need to lead those power cables into the system interconnection protection device 20, the degree of freedom in panel layout and the like is limited. Not even.

The solar cells 15 of each distributed power source 14
The capacity of the inverter 17, the configuration of the control device 22, the operation control means, the islanding detection method, and the like may be any, and are not limited to those of the embodiment.

Also, the control unit 22 sends each distributed power supply 14
The transmission method of the control command or the like may be any of various methods such as a cable transmission method using a power line, a spread spectrum method using a communication line 23, or a wireless method using radio waves.

The control device 22 is of course similarly applicable to the case where the control device 22 is not provided in the system interconnection protection device 20 but is provided in another device or provided alone.

[0048]

The present invention has the following effects. Each of the distributed power supplies 14 is provided with disconnection switches 18 and 19 at the first and second disconnection points. When the system is abnormal, these switches 18 and 19 are transmitted from the common control device 22. Each of the distributed power supplies 14 can be disconnected from the power system 1 by being released according to the respective release command.

In this case, the two parallel disconnection points of each distributed power supply 14 are individually formed by both parallel disconnection switches 18 and 19, and these parallel disconnection switches 18 and 19 are connected to the distributed power supply 14. Irrespective of the number of switches, the switch is formed by a small-capacity and small-sized switch corresponding to the capacity of each distributed power supply 14.

The large common disconnecting switch of the conventional system interconnection protection device is omitted.

Therefore, regardless of the capacity and the number of distributed power supplies 14, each distributed power supply 14 has its own capacity without providing a large-capacity, large-sized disconnection switch in a system interconnection protection device or the like. Small, small capacity two disconnecting switches 1
8 and 19 can be provided, so that the size of the panel of each part of the apparatus does not become large and their large size is prevented, and further, other panels such as a system interconnection protection device by adding a distributed power source 14 are installed. There is no need to increase the capacity, replace, add, etc., and the entire panel size can be unified. In addition, there is no need to draw the power cable of each distributed power supply 14 into a system interconnection protection device, etc. The degree of freedom is not limited.

[Brief description of the drawings]

FIG. 1 is a block connection diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power system 2,14 Distributed power supply 3,15 Solar cell 4,17 Inverter 10,22 Common control device 18 First disconnection switch 19 Second disconnection switch

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Norio Sakae Inventor No. 47 Takanecho Umezu, Ukyo-ku, Kyoto-shi F-term (reference) 5F051 KA03 KA07 KA10 5G066 HA06 HB05 5H007 AA17 BB07 CC05 DB01 FA14 FA19 GA09

Claims (1)

[Claims] 1. A plurality of distributed power supplies connected to a grid each including a solar cell and a stationary inverter, and disconnection of each of the distributed power supplies from the grid and operation of the inverter are common. Centralized control by the control device of the above, and when the system is normal, the distributed power sources are connected to the system, and when the system is abnormal, the distributed power sources are disconnected from the system to operate independently. In the distributed power supply, a first disconnection switch, which includes a contact and the like of the inverse conversion device and forms a first disconnection point, on a system side of the inverse conversion device, A second disconnection switch for forming a disconnection point is provided in series, and the common control device is connected to each of the distributed power supplies by detecting the isolated operation of each of the distributed power supplies when a system abnormality occurs. Equipped with disconnection control means for transmitting the opening command of each disconnection switch Solar power generation apparatus, characterized in that the.