JPH08126338A - Solar power generation system - Google Patents

Abstract

PURPOSE: To prevent a fatal fault which results in the breakage, etc., of a solar power generation system in the system by providing a system control circuit in which protective operation sequences are incorporated so that the process to set the restoring time of the system and another process for limiting the trial number of restoration can be performed together with various kinds of protective operations at every system shutting-down cause. CONSTITUTION: A system control circuit 9 monitors the output frequency of an inverter 4 and, when the circuit 9 judges that a trouble occurs in a system, stops the system by paralleling off the inverter 4 from the system by opening a paralleling-off switch 7. Then the circuit 9 discriminates the kind of the trouble based on an operation sequence and judges whether or not the number of occurrence of the same kind of trouble reaches a set number of times individually set at every kind of trouble. When the judgment result is 'Yes', the circuit 9 opens the main switch of the system and, when the result is 'No', the circuit 9 restarts the system at the point of time when the set time individually set at every kind of trouble is reached.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar power generation system for converting a solar cell output to an AC power supply via an inverter, or a grid-connected solar power system for connecting a solar cell output to an AC power supply system via an inverter. Power generation system.

[0002]

2. Description of the Related Art A solar power generation system in which the output of a DC power source of a solar cell is converted into an AC power source by an inverter, or the output of a DC power source of a solar cell is converted into an AC power source by an inverter and is connected to an existing power system of a commercial power system. As for the grid-connected photovoltaic power generation system which is configured to supply electric power to the load, various configurations have been developed as shown in Japanese Utility Model Publication No. 62-172293 and Japanese Utility Model Publication No. 62-172294.

[0003]

The operation sequence of the protection circuit in the abnormal operation of the inverter and the protection circuit in the system abnormality is such that the output of the inverter is stopped after the protection operation and the corresponding protection stop factor is released, Or
A pattern is repeated in which the factors are automatically canceled and the operation state is restored again after a certain period of time. However,
Depending on the failure condition, there was a possibility of developing a serious failure such as system damage. The present invention aims to solve the above problems.

[0004]

[Means to solve the problem]

(1) In order to achieve the above object, the present invention, in a photovoltaic power generation system for converting a solar cell output into an AC power source through an inverter, detects an abnormality of the inverter and stops the system to perform an inverter protection operation. A sequence of protection operations is performed so that, in the recovery and the recovery after the protection operation, the processing for setting the recovery time for each system stop factor and the processing for limiting the number of recovery attempts are performed together with various protection operations. Is provided with a system control circuit. (2) In order to achieve the above object, the present invention detects an abnormality on the side of an inverter and an AC power supply system in a grid-connected photovoltaic power generation system in which a solar cell output is connected to an AC power supply system via an inverter. Process of performing system shutdown and system disconnection operation to perform protection operation of the inverter and AC power supply system, processing to set recovery time for each abnormal factor in recovery after recovery operation, and recovery recovery attempt A system control circuit incorporating a protection operation sequence is provided so as to perform the process of limiting the number of times together with various protection operations.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described below in detail with reference to the embodiments shown in the accompanying drawings. 1 is a commercial AC power supply system which is an existing power system, 2 is a commercial AC power supply system 1, a load connected to an inverter described below, and 3 is a DC power supply of an inverter described below, which is controlled to track the maximum operating point under each solar radiation condition. Solar cells. Reference numeral 4 denotes an inverter, the input terminal of which is connected to the solar cell 3 and the output terminal of which is connected to the load through the output current detector 5, the low-pass filter 6, the normally-closed disconnecting switch 7, and the interconnection transformer 8. Connected to 2.

The successive constant incorporated in the inverter 4 is changed by the control signal supplied to the control terminal 4a. The control terminal 4a is connected to a system control circuit 9 and a bimodal band filter consisting of two BPFs (bandpass filters) 10 and 11, that is, an output side of a phase control circuit 12. The input side of the system control circuit 9 is connected to the output side of the interconnection transformer 8 via the AC voltage output device 13. The other input side of the system control circuit 9 is connected to the output terminals of the solar cell 3 and the inverter 4, respectively.

The phase control circuit 12 constitutes a control system of the output current feedback loop of the inverter 4. The input of the bimodal BPF (band filter) 12 obtains the AC voltage at the interconnection point via the AC voltage detector 14. The bimodal BPF 12 has, for example, a frequency of the AC power supply system 1 of 5
When it is 0HZ, the center frequency is set at two positions of 40HZ and 60HZ, and in the vicinity of 50HZ between them, the gain-frequency differential value is set to zero and the phase is set to zero.

The system control circuit 9 includes an inverter 4
Detects the system voltage, the system voltage frequency, and the inverter output current in a state in which is connected to the AC power system. The system control circuit 9 receives the BPF 10 and the BPF 10 based on these signals.
The output current of the inverter 4 is in phase with the system voltage frequency, that is, the load 2 by changing the Q value of the PF 11 and moving the center frequency of each BPF 10, 11 with the system voltage frequency as a reference. The output voltage is controlled to have the same phase as the voltage, and thus the output power control with a power factor of 1 is performed.

The output line of the system control circuit 9 is
The output line is connected to the control terminals of the BPFs 10 and 11, and the output line is configured to supply a phase control signal to the control terminals of the BPFs 10 and 11. In the figure, 15 is a smoothing capacitor.

The operation of the system control circuit 9 will be described below with reference to the flow chart shown in FIG. When the system is in operation (step 1) and the system 1 has a power failure, the relationship of v ′ (load voltage) = v (system voltage) in the normal operation is broken, and the output current i of the inverter 4 is determined by the load 2. It is controlled based on the voltage. In this case, the control system of the output current feedback loop of the inverter 4 becomes stable at the feedback frequency at which the phase of the transfer function from i to i ′ becomes zero.

That is, according to the phase characteristics of the bimodal BPF 12, for example, when i'is a leading phase with respect to i, it is controlled so as to increase the frequency of i, and when it is a lagging phase, it is controlled so as to decrease. As a result, i moves to around 55HZ or 45HZ. The system control circuit 9 monitors the output frequency of the inverter 4, and if this frequency change occurs, determines that an abnormality has occurred in the system (step 2), excites a disconnecting relay (not shown), and disconnects the disconnecting switch. 7 is opened, the inverter 4 is disconnected from the system, and the system is stopped (step 3). In addition, the system control circuit 9 is a system 1
In addition to the power outage, the system operation status is monitored, and if an error occurs, the system is stopped.

Next, the system control circuit 9 determines the content of the abnormal stop based on the operation sequence incorporated therein (step 4). Next, the content of the abnormal stop is stored in the memory for each content (steps 5-1 to n). Next, for each of the abnormal stop contents, the number of occurrences is set individually for each of the abnormal stop contents, and the set number of times NA, N is set.
It is determined whether or not B and Nn are reached (steps 6-1 to 6-1).
n).

When affirmative determination is made, the main switch (not shown) of the system is turned off, the system is seriously stopped (step 12), an alarm is output (step 13), and a display device (not shown) is provided. The content of the abnormal stop is displayed in () (step 14). If a negative determination is made in each of steps 6-1 to n, then the content of the abnormal stop is displayed on the display device (steps S7-1 to n). Next, the system is prepared for restart (steps S8-1 to n),
It is determined whether or not the disconnection state has reached the set time set individually for each abnormal stop content (steps 9-1 to n), and if the determination is affirmative, the display of the abnormal stop content is canceled (step S10- 1 to n), transition to restart (step 1
1).

Although the above embodiment is applied to the system of the system interconnection type, it can be applied to the case of not being the system interconnection type.
In this case, the system control circuit stops the system in step 3, and determines in step S9-1 to n whether or not the stopped state of the system has reached the set time. Other operations are the same as those of the grid interconnection type.

[0015]

Since the present invention is configured as described above, it is possible to prevent a serious failure such as damage to the system.

[Brief description of drawings]

FIG. 1 is a flowchart showing an operation of a system control circuit.

FIG. 2 is a block circuit diagram of the system.

[Explanation of symbols]

 1 commercial AC power supply 2 load 3 solar cell 4 inverter 5 output current detector 6 low-pass filter 7 disconnection switch 8 interconnection transformer 9 system control circuit 10 bandpass filter 11 bandpass filter 12 phase control circuit (double-peak bandpass filter) ) 13 AC voltage detector 14 AC voltage detector

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Yamane 461 Imaiminami-cho, Nakahara-ku, Kawasaki-shi, Kanagawa Miki Puri Co., Ltd. (72) Inventor Nobu Kawasaki 3-7-4 Shibaura, Minato-ku, Tokyo

Claims (2)

[Claims] 1. A photovoltaic power generation system for converting an output of a solar cell into an AC power source via an inverter, a process of detecting an abnormality of the inverter, stopping the system to perform a protection operation of the inverter, and a reprocessing after the protection operation. A system control circuit with a built-in protection operation sequence is provided to perform the process of setting the re-recovery time for each individual system stop factor and the process of limiting the number of re-recovery attempts at the time of recovery along with various protection operations. A solar power generation system characterized by that. 2. In a grid-connected photovoltaic power generation system in which the output of a solar cell is linked to an AC power supply system via an inverter, a system stop and grid disconnection operation are performed by detecting an abnormality on the side of the inverter and the AC power supply system. Various types of protection are performed: the process of protecting the inverter and the AC power supply system, the process of setting the re-recovery time for each error factor in the re-recovery after the protective operation, and the process of limiting the number of re-recovery attempts. A photovoltaic power generation system comprising a system control circuit in which a protection operation sequence is incorporated so as to be performed together with the operation.