JP4562932B2 - System protection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photovoltaic power generation apparatus that performs system interconnection with a commercial AC power supply.
[0002]
[Prior art]
In-house power generators such as solar power generation as a clean energy source are showing signs of widespread use in recent years because grid interconnection with commercial AC power sources has become possible. In particular, solar power generation does not make noise and has no harmful emissions.
Inverters are used in photovoltaic power generation systems that are connected to commercial AC power supplies, but the “Power” compiled by the Agency for Natural Resources and Energy to protect against accidents in either commercial power supplies or photovoltaic power generation systems. As indicated in the “Guidelines for grid interconnection technical requirements”, it is necessary to provide two mechanical opening / closing points between them, or to perform one mechanical opening / closing point and a gate block of an inverse conversion device. .
[0003]
Moreover, when performing a self-sustaining operation by the output of the reverse conversion device, it is necessary to satisfy one of the following conditions 1) and 2) in order to prevent reverse charging and asynchronous charging to the system.
1) Provide two mechanical opening / closing points, or one mechanical opening / closing point and one manually opening / closing point.
2) Provide a mechanical switching prevention mechanism at the time of system stop, a self-sustained operation transition prevention function at the time of mechanical switching point failure, and an asynchronous switching prevention mechanism at the time of grid connection recovery, along with one mechanical switching point.
[0004]
In the photovoltaic power generator that performs the independent operation by the output of the reverse converter, an electromagnetic switch 5a and a circuit breaker 6a are provided between the reverse converter 11 and the commercial AC power source 3 as shown in FIG. A system that satisfies the above-mentioned condition 1) has been put into practical use by taking it from the connection point between the electromagnetic switch 5a and the circuit breaker 6a.
[0005]
[Problems to be solved by the invention]
However, in the above-described method, there is a problem that the circuit breaker is manually operated when the grid connection is turned ON / OFF, and the operation becomes complicated because automatic operation is not possible.
[0006]
The present invention has been made under such a background. The above-mentioned condition 2) (one mechanical opening / closing position, together with a mechanism for preventing erroneous input when the system is stopped, and a transition to independent operation when a mechanical opening / closing position fails) An object of the present invention is to provide a solar power generation device that can satisfy an obstruction function and a mechanism for preventing asynchronous charging at the time of grid connection return) and can perform automatic operation.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 is a system interconnection function for converting DC power obtained by a solar cell into AC power by an inverse conversion device and performing system interconnection with a commercial power supply system via one mechanical switch. In the solar power generation device having a self-sustaining operation function by the output of the reverse conversion device, in order to prevent asynchronous charging at the start of grid connection, after the reverse conversion device is temporarily stopped, gate block means for operating again, One of the signals generated first among the grid interconnection instruction for instructing the grid interconnection generated after the reverse operation of the inverse converter by the gate block means and the independent operation instruction signal for instructing the independent operation is performed. Interlock means for sending only the signal, and when the grid connection instruction signal is sent and the voltage of the commercial power system is normal, the mechanical switch is closed to A grid connection locking means for starting, a self-sustained operation locking means for starting the autonomous operation when the autonomous operation instruction signal is sent and the mechanical switch is opened and the grid interconnection is not performed; And the interlock means is a hardware interlock formed by a transistor circuit .
[0008]
According to the present invention, the reverse conversion device and the commercial AC power source are connected via a single mechanical switch, and the erroneous input prevention mechanism at the time of system stop, which cannot be turned on unless the system voltage is normal, mechanical By providing a function to prevent autonomous operation transition when a switching point failure occurs, and a reverse blocking device that temporarily stops the inverter at the time of grid recovery, it is equipped with an asynchronous charging prevention mechanism that uses gate block means to restart operation. The conditions can be satisfied and the solar power generator can be operated automatically.
[0009]
The invention described in claim 2 is the solar power generation device according to claim 1, before Symbol mechanical switch is characterized in that an electromagnetic switch.
[0010]
According to the present invention, the hardware interlock is used as an interlock means for sending out only one signal generated first among the grid interconnection instruction for instructing grid interconnection and the independent operation instruction signal for instructing independent operation. By adopting it, it is possible to avoid software malfunctions.
Moreover, manual operation can be eliminated by using an electromagnetic switch as a mechanical switch.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a connection diagram showing a configuration of a photovoltaic power generator according to an embodiment of the present invention.
In this figure, the code | symbol 1 is a solar cell panel, is connected with the commercial power source 3 via the output control apparatus 2, and performs grid connection.
[0012]
The output control device 2 includes an inverse conversion device 11 that converts the input DC power of the solar battery panel 1 into AC power and outputs the AC power, and this AC power is referred to as a make contact (hereinafter referred to as a contact) of the electromagnetic switch 23. ) The system is linked to the commercial AC power source 3 through 23a.
Further, the AC power is output to the self-supporting output terminal 24 via the contact a 22a of the electromagnetic switch 22.
[0013]
The relay 21, the a contact 21a of the relay 21, the electromagnetic switch 22, the a contact 22a of the electromagnetic switch 22, the electromagnetic switch 23, the break contact (hereinafter referred to as b contact) 23b of the electromagnetic switch 23, and the transistor 1 to 18 are connected as shown in FIG. 1 and perform gate block by intervening in the gate control unit 111 of the reverse conversion device 11, and the inverter block by the gate block means 113 that temporarily stops and restarts the inverter 112. A predetermined operation is performed based on the control signal of the grid interconnection instruction 13 or the autonomous operation instruction 14 generated after the re-operation is performed, and the grid interconnection or the autonomous operation is performed.
[0014]
The signal of the grid connection instruction 13 or the independent operation instruction 14 is not generated at the same time by the software. However, considering the case where it malfunctions for some reason, the hardware interlock circuit is configured by the transistor 15 and the transistor 16. And at least both transistor 17 and transistor 18 are not simultaneously excited.
[0015]
The signal of the grid connection instruction 13 is generated after the gate block means 113 stops the output of the gate control unit 111, temporarily stops the inverter 112, performs re-operation and confirms the synchronous operation with the commercial AC power source 3. If the transistor 16 is not turned on, the transistor 17 is excited and turned on, and the relay 21 is excited. Excitation of the relay 21 closes the contact a 21a of the relay 21 inserted in series with the electromagnetic switch 23, and the electromagnetic switch 23 is excited if the voltage of the commercial AC power supply is normal. Excitation of the electromagnetic switch 23 closes the a contact 23a of the electromagnetic switch 23 inserted between the output of the reverse conversion device 11 and the commercial AC power supply 3, and the grid interconnection is started.
[0016]
On the contrary, if the signal of the independent operation instruction 14 is generated and the signal of the grid connection instruction 13 is not present, the transistor 18 is excited and the electromagnetic switch 23 is not excited, so that the b contact 23b is closed, The electromagnetic switch 22 is excited.
Accordingly, the a contact 22 a is closed, and the AC power of the inverse conversion device 11 is output to the self-supporting output terminal 24.
[0017]
Next, a more detailed operation will be described according to the flowcharts of FIGS. FIG. 2 is a flowchart for performing grid interconnection, and FIG. 3 is a flowchart for performing independent operation.
[0018]
In step S1 in FIG. 2 (hereinafter simply referred to as S1 etc.), it is determined whether or not there is a control signal for grid connection instruction. If there is no signal, the switch for interconnection is turned off in S6 and the process is terminated. .
The signal of the grid connection instruction in S1 is stopped by the gate block means 113 of FIG. 1 to stop the output of the gate control unit 111, temporarily stop the inverter 112, and restart the operation to confirm the synchronous operation with the commercial AC power source 3. After that, it is sent out and the process proceeds to S2, and it is confirmed that there is no independent operation signal.
If the self-sustained operation signal is output, the transistor 15 in FIG. 1 is turned on, so that the grid connection instruction signal is suppressed and the transistor 17 is not excited. If there is no self-sustained operation signal, the system interconnection relay 21 is excited by exciting the transistor 17 in S3.
[0019]
In S4, it is determined whether or not the voltage of the commercial AC power supply 3 is normal. If it is normal, the interconnection electromagnetic switch 23 is excited and the a contact 23a is closed to start the grid interconnection, and the process returns to S1. The determination as to whether or not the voltage of the commercial AC power supply 3 is normal is made by exciting the electromagnetic switch 23 connected in series with the a contact 21 a by the commercial AC power supply 3.
[0020]
Next, the operation in the case of performing the independent operation will be described with reference to FIG.
First, in S11, it is determined whether or not there is an independent operation instruction signal. If there is this signal, the process proceeds to a process of determining whether or not there is a grid connection signal in S12. If there is no stand-alone operation instruction in S11, the process proceeds to S16, the self-sustained operation electromagnetic switch 22 is turned off, and the process ends.
If there is no grid connection signal in S12 and the transistor 16 is not ON, the transistor 18 is excited in S13. When there is a grid connection signal in S12, the process proceeds to S16, the self-sustaining operation electromagnetic switch 22 is turned off, and the process is terminated.
[0021]
Next, in S14, it is determined whether or not the grid connection electromagnetic switch 23 is OFF. This determination is made by inserting the b contact 23b of the grid connection electromagnetic switch 23 in series with the exciting coil of the electromagnetic switch 22 for independent operation.
If the grid connection electromagnetic switch 23 is ON for some reason, the system enters standby in S14, and if it is OFF, the self-sustaining operation electromagnetic switch 22 is excited in S15 to close the contact a 22a. The output of the reverse conversion device 11 is connected to the self-supporting output terminal 24 to perform self-supporting operation.
[0022]
The operation of one embodiment of the present invention has been described in detail with reference to the drawings. However, the present invention is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. Are also included in the present invention.
For example, the present invention is not limited to a system protection device for a solar power generation device, and can also be applied to a grid interconnection device such as a wind power generation device or a gas turbine power generation device.
[0023]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
According to the first aspect of the present invention, the reverse conversion device and the commercial AC power supply are connected via a single mechanical switch, and the erroneous input prevention mechanism at the time of system stop that cannot be input unless the system voltage is normal. By providing a function for preventing the transition to independent operation when a mechanical switching point failure occurs and a mechanism for preventing asynchronous charging by means of a gate block means that restarts the inverter after the reverse conversion device is stopped once the connection is restored, The conditions of the “Guidelines” can be satisfied and the photovoltaic power generator can be operated automatically.
[0024]
Further, according to the invention of claim 2, as the interlock means for sending out only one signal generated first among the signal of the grid connection instruction for instructing the grid connection and the signal of the independent operation instruction for instructing the independent operation. By adopting the hardware interlock, it is possible to avoid software malfunction and the like. Moreover, manual operation can be eliminated by using an electromagnetic switch as a mechanical switch.
[Brief description of the drawings]
FIG. 1 is a connection diagram illustrating a configuration of a photovoltaic power generator according to an embodiment of the present invention.
FIG. 2 is a flowchart for explaining an operation when grid connection is performed.
FIG. 3 is a flowchart for explaining the operation in the case of performing an independent operation.
FIG. 4 is a block diagram showing the configuration of a conventional photovoltaic power generation apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Solar cell panel 2, 4 ... Output control apparatus 3 ... Commercial alternating current power supply 5a ... Electromagnetic switch 6a ... Circuit breaker 11 ... Inverse converter 111 ... Gate control part 112 ... Inverter 113 ... Gate block means 12 ... Control signal 13 ... Grid connection instruction 14 ... Independent operation instruction 15, 16, 17, 18 ... Transistor 21 ... Relay 21a ... Make contact 22 of relay 21 ... Electromagnetic switch 22a ... Make contact 23 of electromagnetic switch 22 ... Electromagnetic switch 23a ... Electromagnetic switch 23a Make contact 23b of switch 23 ... Break contact of electromagnetic switch 23

Claims (2)

DC power obtained by solar cells is converted into AC power by an inverter, and a grid connection function for performing grid connection with a commercial power supply system via one mechanical switch, and independent operation by the output of the inverter In the solar cell power generator having a function,
In order to prevent asynchronous charging at the start of grid connection, after temporarily stopping the reverse conversion device, gate block means for operating again,
A grid interconnection instruction that indicates a grid interconnection that occurs after the re-operation of the inverse converter by the gate block means;
Interlock means for sending out only one signal generated first among the signals of the independent operation instruction for instructing the independent operation;
When the grid connection instruction signal is sent and the voltage of the commercial power system is normal, the grid connection locking means for closing the mechanical switch and starting the grid connection;
When the autonomous operation instruction signal is sent, and when the mechanical switch is opened and grid interconnection is not performed, an autonomous operation locking means for starting autonomous operation is provided ,
The system protection apparatus , wherein the interlock means is a hardware interlock formed by a transistor circuit . System protection system according to claim 1, wherein the pre-Symbol mechanical switch is an electromagnetic switch.

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