JP2005168156A - Ground fault countermeasure device and power generating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground fault countermeasure device capable of effectively utilizing power generated with a power generating device by re-starting power supply to a load system and a power system by using power generated with a module, in which a ground fault does not occur, by separating the connection of the module, in which the ground fault occurs, and a power conditioner by quickly specifying the module, in which the ground fault occurs, when the ground fault occurs in the power generating device. <P>SOLUTION: Switches 21-24 are provided corresponding to a plurality of the modules 11-14 constituting the power generating device respectively. When the ground fault is detected by a ground fault detector 10, a control part 100 controls the opening/closing of the switches 21-24 on the basis of preset prescribed procedures, and consequently, the module, in which the ground fault occurs, is specified. When the control part 100 specifies the module in which the ground fault occurs, the information is outputted to a notification part 200. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ground fault countermeasure device used in a power generation system, and more particularly to a ground fault countermeasure device used in a solar power generation system.

In a photovoltaic power generation system, in general, in order to obtain a desired voltage, a plurality of battery cells are connected in series to form a module, and in order to obtain an output power capacity, a plurality of modules are connected in parallel. Connect to form a power generator.
The DC power generated by the power generator is converted into AC power by a power conditioner configured by an inverter, a booster, a control device that controls each unit, and the like, and is supplied to a load system and a power system.
By the way, in the above-mentioned electric power generating apparatus, insulation of a battery cell, wiring, etc. may be destroyed for some reason, and a ground fault may occur.
In this case, it is necessary to identify the location where the insulation is broken and take appropriate measures.
Therefore, for example, in Japanese Patent Laid-Open No. 2001-21606 (Patent Document 1), a voltage divider is connected between the output lines of the solar cells, and a current detector is connected between the voltage dividing point of the voltage divider and the ground potential. And the technique which detects a ground fault correctly is disclosed by adjusting the voltage dividing ratio of a voltage divider so that this detection result may be set to zero.
JP 2001-21606 (paragraphs [0018] to [0039] and FIGS. 1 to 5)

By the way, in patent document 1 mentioned above, when a ground fault is detected, the conductor which has connected the electric power generating apparatus and the power conditioner is open | released, and also the operation | movement of a power conditioner is stopped. According to the present invention, high safety can be ensured when a ground fault occurs, but there are the following problems.
That is, in the invention of Patent Document 1 described above, when a ground fault location is detected even in a part of the power generation device, the operation of the power conditioner is stopped and the supply of generated power is completely stopped. There has been a problem that the power generated by a normal module in which no entanglement has occurred is wasted.

  The present invention has been made to solve the above problem. When a ground fault occurs in the power generation device, the module in which the ground fault has occurred is immediately identified, and the module and the power conditioner are connected. Provides a ground fault countermeasure device and a power generation system that can effectively use generated power by ensuring safety by separating and maintaining a connection with a power conditioner for modules that do not generate a ground fault The purpose is to do.

  In order to solve the above problems, the present invention employs the following means.

  The ground fault countermeasure device of the present invention is a ground fault provided between a plurality of modules constituting a power generation device and a power conditioner for supplying power generated by these modules to a load system or a power system. A countermeasure device, provided in correspondence with each of the modules, and an opening / closing means disposed between the module and the power conditioner, and an opening / closing set in advance when a ground fault is detected. Control means for identifying the module in which the ground fault has occurred by controlling the opening and closing of each of the opening and closing means based on the procedure.

The module of the power generation apparatus is configured by directly connecting a plurality of battery cells. The power generator is configured by connecting a plurality of modules in parallel to obtain an output power capacity.
The power conditioner is mainly for converting DC power generated by the power generator into AC power and supplying it to a load system or power system. For example, an inverter, a booster, and control for controlling each unit Consists of devices and the like.
Opening and closing means constituting the ground fault countermeasure device are provided corresponding to each module of the power generation device, and by opening this opening and closing means, the module can be separated from the circuit, ensuring safety. it can.
The control means constituting the ground fault countermeasure device controls the opening / closing of the opening / closing means based on a preset opening / closing procedure when a ground fault is detected by the ground fault detecting means for detecting a ground fault. Identify the module where the ground fault occurred.
For example, the control means sequentially switches the combination of the opening means to be inserted and the opening / closing means to be opened, and specifies the module in which the ground fault has occurred based on the presence or absence of the ground fault detection when switching.
Specific examples of the opening / closing procedure include the following.
For example, when a ground fault is detected, the control means first opens all the opening / closing means and then sequentially turns on each opening / closing means, and a ground fault occurs depending on whether or not the ground fault is detected at that time. Identify the module that
When a ground fault is detected, the control means first opens all the opening / closing means, then opens one opening means and all the other opening means, and sequentially switches the opening / closing means to open. You may make it identify the module which the entanglement generate | occur | produced.
In addition, the control means, for example, divides the opening / closing means into a plurality of groups, performs the opening / closing operation for each group, and specifies by gradually narrowing down the modules in which the ground fault occurs. Also good. According to this operation, it is possible to identify a module in which a ground fault has occurred with a small number of opening / closing operations, compared to a method in which switches are inserted one by one.
The control means includes a CPU (Central Processing Unit), ROM (Read
Only Memory), RAM (Random
For example, the ROM stores a program describing an opening / closing procedure of the opening / closing means when a ground fault is detected. When a ground fault is detected, the CPU expands the program stored in the ROM to the RAM, and controls opening / closing of the opening / closing means based on the expanded program execution procedure.
In addition, the ground fault countermeasure device does not need to include a ground fault detection means. For example, it may be provided in a power conditioner. In short, it is sufficient that information indicating that a ground fault has occurred is transmitted to the control means.

  The ground fault countermeasure apparatus of the present invention is further characterized by further comprising notification means for notifying information on the module identified as having a ground fault.

The notifying means notifies information about the module in which the ground fault has occurred when the module in which the ground fault has occurred is specified by the ground fault detecting means.
As a result, it is possible to notify the user or system administrator of the module in which a ground fault has occurred immediately.
Note that examples of the notification method include a visual notification method such as lighting of a lamp, and a visual notification method such as an alarm sounding. The notification destination may be notified to a display device provided in the system, or to the system administrator via a predetermined network (for example, a dedicated line, the Internet, etc.). Also good.

  Moreover, the ground fault countermeasure apparatus of this invention is suitable for a power generation system, and it becomes possible by using this ground fault countermeasure apparatus to use effectively the electric power generated by the power generator.

  The ground fault countermeasure apparatus of the present invention has the following effects.

  According to the present invention, it is possible not only to detect a ground fault, but also to identify a module in which a ground fault has occurred. With respect to, the power generated by the power generation device can be used effectively by resuming the supply of power from the power generation device while being connected to the power conditioner.

When a module with a ground fault is identified by the ground fault detection means, a notification means is provided for notifying information about the module with the ground fault. It is possible to notify about the module in which the error occurred.
As a result, it is possible to quickly respond to the occurrence of a ground fault, and at the same time, it is possible to easily grasp the status of the module in which the ground fault has occurred and to perform quick and appropriate repair work.
In addition, even if the ground fault detection means is erroneously operated, it is possible to immediately confirm that the malfunction has occurred and to prevent unnecessary seconding or contact.

Hereinafter, an embodiment of a ground fault countermeasure device according to the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a photovoltaic power generation system according to an embodiment of the present invention.
In this figure, the code | symbol 1 is a solar cell (electric power generating device), and generate | occur | produces direct-current power in response to sunlight irradiation. The solar cell 1 is configured by connecting a plurality of modules in which several solar cells are connected in series, in parallel. Note that the number of solar cells in series and the number of modules in parallel are appropriately selected so that the voltage and power capacity necessary for the photovoltaic power generation system can be obtained.
Reference numeral 2 denotes a connection box (including a ground fault countermeasure device) 2, and wirings for outputting DC power generated by each module of the solar cell 1 are connected in parallel here. Thereby, the electric power generated by each module is supplied to the power conditioner 3 via one power line (P in the figure).
The DC power generated by the solar cell 1 is converted into AC power by the inverter 31 in the power conditioner 3, and the harmonic component is removed by the noise filter 32.
The AC power from which the harmonic component has been removed by the noise filter 32 is supplied to the load system or the power system. In addition, as load connected to a load system, household appliances, such as an air conditioner, a refrigerator, and a vacuum cleaner, are mentioned, for example.
On the output side of the power conditioner 3, a conductor 33 is provided for disconnecting the connection between the power conditioner 3 and the system and ensuring safety when an abnormality occurs.
The control unit 34 performs PWM control on the switching elements constituting the inverter 31 so that the power supplied to the load system is AC power having a predetermined voltage and a predetermined frequency. Further, when a ground fault is detected by a ground fault detector provided in the connection box 2 described later, the control of the inverter 31 is temporarily stopped, the conductor 33 is once opened, and the power conditioner 3 is disconnected from the system.

Next, the junction box 2 that connects the power generator 1 and the power conditioner 3 will be described with reference to FIG.
FIG. 2 is a diagram illustrating a configuration in which a solar cell 1 that functions as a power generation device is connected to a junction box 2 according to an embodiment of the present invention.
As shown in this figure, the modules 11 to 14 constituting the solar cell 1 are connected in parallel by a connection box 2. In the connection box 2, corresponding to each of the modules 11 to 14, a circuit is provided for the module in which an abnormality occurs when maintenance or inspection of the solar cell 1 or an abnormality such as a ground fault occurs in a part of the solar cell 1. Switches (opening / closing means) 21 to 24 for disconnecting from the circuit are provided, and the circuit is opened and closed under the control of the control unit 100.
A backflow prevention diode 5 is provided corresponding to each module. This is to prevent the flow of current that occurs when the power generation voltage of each module differs depending on the installation position of the modules 11 to 14, the irradiation condition of sunlight, and the like.
A ground fault detector (ground fault detection means) 10 for detecting a ground fault is provided on the power conditioner 3 side of the connection point where the modules 11 to 14 are connected in parallel. The ground fault detector 10 detects a difference current flowing through both electric wires by a magnetic field generated from each of the current forward and return wires, and if the detection result is equal to or greater than a certain value, it indicates a ground fault. (Hereinafter referred to as “ground fault signal”) is output to the control unit 100.
Furthermore, after each module is connected in parallel, a conductor 6 for disconnecting the connection between the connection box 2 and the power conditioner 3 is disposed in the middle of a path for supplying power to the power conditioner 3.
When receiving the ground fault signal, the control unit (control means) 100 opens the conductor 6 and then controls the opening and closing of the switches 21 to 24 based on a predetermined procedure set in advance. Identifies the module where the occurred.
Furthermore, the control unit 100 outputs information on the module identified by the occurrence of the ground fault and the above-described opening / closing operation to the notification unit (notification unit) 200.
The control unit 100 includes a CPU (Central Processing Unit) (not shown) and a ROM (Read
Only Memory), RAM (Random
For example, the ROM stores opening / closing programs of the switches 21 to 24 when a ground fault is detected. As a result, when a ground fault is detected, the CPU expands the open / close program stored in the ROM to the RAM, and controls the opening / closing of the switches 21 to 24 based on the expanded program execution procedure. It is possible to identify the module in which the error occurred.
The notification unit 200 notifies the outside that a ground fault has occurred based on the information received from the control unit 100 and the occurrence location. The notification method includes, for example, notification to the outside of the apparatus by lighting a lamp, ringing an alarm, etc., and information transmission through a network. The notification destination may be notified to a ground fault countermeasure device or a display device provided in the power generation system, or may be notified to the power generation system administrator via the Internet or the like.
Here, in the present embodiment, the ground fault countermeasure device is configured by the switches 21 to 24, the control unit 100, the ground fault detector 10, and the notification unit 200.

Next, the operation of the ground fault countermeasure device when a ground fault occurs in any module or its wiring in the photovoltaic power generation system having the above configuration will be described.
Here, a case where a ground fault occurs in a part of the module 12 will be described.
First, when a ground fault occurs, the ground fault detector 10 detects a ground fault and outputs a ground fault signal to the control unit 100. The control unit 100 opens the conductor 6 and outputs a signal indicating that a ground fault has been detected to the control unit 34 in the power conditioner 3 (see FIG. 1). Thereby, the control part 34 in the power conditioner 3 opens the conductor 33 and stops the control of the inverter 31. As a result, power supply to the load system or the like is temporarily stopped.
Furthermore, the control unit 100 in the connection box 2 outputs information indicating that a ground fault has occurred to the notification unit 200. Thereby, the notification unit 200 notifies that a ground fault has occurred.
Next, the control unit 100 opens all the switches 21 to 24 to make them open.
Subsequently, the control unit 100 turns on the switch 21 and closes it, and then turns on the conductor 6. At this time, since a ground fault has not occurred in the module 11, the ground fault detector 10 does not detect a ground fault. Therefore, the control unit 100 recognizes that no ground fault has occurred in the module 11.
Subsequently, the control unit 100 turns on the switch 22 while maintaining the above open / closed state. At this time, since the module 12 generates a ground fault, the ground fault detector 10 detects the ground fault and outputs a ground fault signal to the control unit 100.
Upon receiving this signal, the control unit 100 recognizes that the ground fault has occurred in the module 12 and stores it, and opens the switch 21.
Next, the control unit 100 turns on the switch 23 while maintaining the above open / closed state. At this time, since a ground fault has not occurred in the module 13, the ground fault detector 10 does not detect a ground fault. Therefore, the control unit 100 recognizes that no ground fault has occurred in the module 13. Similarly, the switch 24 is turned on and it is confirmed that no ground fault has occurred in the module 14.

As a result of the operation of this switch, only the switch 22 corresponding to the module 12 in which the ground fault has occurred is opened, and the switches 21, 23, and 24 corresponding to the other modules 11, 13, and 14 are turned on. It will be in the state.
In this state, the control unit 100 outputs a signal indicating that the control of the inverter 31 is started to the control unit 34 (see FIG. 1) in the power conditioner 3. When receiving the signal, the control unit 34 turns on the conductor 33 and resumes control of the inverter 31. As a result, the power generated by the other modules 11, 13, and 14 in which no ground fault has occurred is supplied to the load system or power system by the power conditioner 3.
After the series of operations described above is completed, the control unit 100 outputs information indicating that a ground fault has occurred in the module 12 to the notification unit 200. Thereby, the location where the ground fault has occurred is notified by the notification unit 200.

As mentioned above, according to embodiment mentioned above, the following effects can be acquired.
Switches 21 to 24 are provided corresponding to the modules 11 to 14, respectively. Then, when a ground fault is detected by the ground fault detector 10, the control unit 100 controls the opening and closing of the switches 21 to 24 based on a predetermined procedure set in advance, thereby causing a ground fault. Identify the module. In this way, the control unit 100 identifies the module in which the ground fault has occurred, thereby disconnecting the connection with the power conditioner 3 for the module in which the ground fault has occurred, and the power conditioner 3 for the other modules. And connected. As a result, the supply of power from the power generation device 1 can be resumed, and the power generated by the power generation device 1 can be used effectively.

Further, the notification unit 200 notifies that a ground fault has occurred and a module in which the ground fault has occurred. Thereby, the user or the manager of the power generation system can immediately know that the ground fault has occurred or the module in which the ground fault has occurred.
As a result, it is possible to quickly respond to the occurrence of a ground fault, and at the same time, it is possible to easily grasp the status of the module in which the ground fault has occurred and to perform quick and appropriate repair work.
In addition, even if the ground fault detection means is erroneously operated, it is possible to immediately confirm that the malfunction has occurred and to prevent unnecessary seconding or contact.

In the above-described embodiment, information indicating the occurrence of a ground fault is output to the notification unit 200 when a ground fault is detected. In addition, information indicating that a ground fault has occurred may be output.
In addition, the control unit 100 instructs the control unit 34 in the power conditioner 3 to resume control of the inverter 31 and the like after identifying the module in which the ground fault has occurred, but is not limited to this timing. When at least one normal module is recognized, that is, in the above-described embodiment, when the switch 21 is turned on and it is recognized that a ground fault has not been detected, It may be instructed to resume the control 31.

  In the above-described embodiment, the example in which the switches 21 to 24 are sequentially inserted has been described. However, the order of insertion is not limited to this. For example, as described above, one normal module is provided. However, when the inverter control is resumed at the time when it is recognized, the control unit 100 may execute a detection procedure for starting detection from a module having a large power generation capacity from the viewpoint of early recovery of power supply.

Moreover, in the said embodiment, when a ground fault generate | occur | produced and the ground fault was detected by the ground fault detector 10, it was supposed that all the switches 21-24 were open | released, However, this operation is not performed but the following operation is performed. The opening / closing operation may be performed according to a procedure.
That is, from the state where all the switches are turned on, first, one of the switches is opened and the conductor 6 is turned on. At this time, if a ground fault has occurred in the module corresponding to the opened switch, the ground fault is not detected by the ground fault detector 10. Thereby, the control part 100 can pinpoint the module corresponding to the open switch as a ground fault generation | occurrence | production location. On the other hand, if a ground fault is detected again even if the switch is opened, the conductor 6 is opened once, and any other switch is opened, and the conductor 6 is turned on again. To do. This operation is repeated until no ground fault is detected. By this operation, it is possible to specify that a ground fault has occurred in the module corresponding to the switch opened immediately before the ground fault is no longer detected.

Moreover, in the above-mentioned embodiment, when a ground fault occurs and a ground fault is detected by the ground fault detector 10, after opening all the switches 21 to 24, the switches are turned on one by one. However, the module that caused the ground fault can be identified by the following procedure.
First, the switches are divided into a plurality of groups (for example, the switch 11 and the switch 12 are a first group, the switch 13 and the switch 14 are a second group, etc.). Each time an open / close operation is performed, a group in which a ground fault has occurred is identified. Thereafter, the switching operation is performed for each switch in the group, and the switch in which the ground fault has occurred is specified.
According to this operation, it is possible to identify a module in which a ground fault has occurred with a small number of opening / closing operations, compared to a method in which switches are inserted one by one.
This is particularly effective when the number of modules is large. Alternatively, the number of switches constituting the group may be gradually reduced to narrow down the ground fault locations in stages.
Note that other procedures as described above can also be realized by storing sequence data according to the procedures in the memory in the control unit 100.

In the above-described embodiment, the ground fault detector 10 is provided in the junction box 2, but may be provided in the power conditioner 3. In this case, the installation place is between the conductor 6 and the inverter 31 in the power conditioner 3.
Further, the function of the control unit 100 may be included in the control unit 34 in the power conditioner 3.
Furthermore, the control unit 100 is configured by a CPU, a RAM, a ROM, and the like. However, the control unit 100 is not limited to this, and any configuration that can realize the opening / closing operation of the switch described above is a monitoring server connected to the network. Any configuration may be used, such as sending and receiving control signals.

It is a block diagram which shows the structure of the solar energy power generation system which concerns on one Embodiment of this invention. It is a block diagram which shows the connection structure of the electric power generating apparatus 1 and the connection box 2 which concern on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power generator 2 Connection box 3 Power conditioner 5 Backflow prevention diode 6 Conductor 10 Ground fault detectors 11-14 Modules 21-24 Switch 31 Inverter 32 Noise filter 33 Conductor 34 Control part 100 Control part 200 Notification part

Claims (3)

A ground fault countermeasure device provided between a plurality of modules constituting a power generation device and a power conditioner for supplying power generated by these modules to a load system or a power system,
Opening / closing means provided corresponding to each of the modules, and disposed between the module and the power conditioner;
Control means for identifying a module in which a ground fault has occurred by controlling the opening and closing of each of the opening and closing means based on a preset opening and closing procedure when a ground fault is detected, Ground fault countermeasure device. The ground fault countermeasure apparatus according to claim 1, further comprising notification means for notifying information about the module identified as having a ground fault. A plurality of modules constituting the power generation device;
A power conditioner for supplying the power generated by the module to the load system or the power system;
A ground fault detection means for detecting a ground fault;
A power generation system comprising the ground fault countermeasure device according to claim 1.

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