JPH0993821A - System linked operation control system for distributed power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To disconnect a distributed power supply surely when power supply from a commercial power supply is interrupted under a state where a commercial power supply and a distributed power supply are supplying power to a load by being linked mutually. SOLUTION: A signal of specific frequency is superposed by providing a signal superposition means 2 on the power supply side of a commercial power supply system. A system linkage protective unit 8 comprises means 8a for receiving the signal of specific frequency and a control means 8b. When the receiving means receives the signal of specific frequency, a switch 7 is closed through the control means 8b to connect a distributed power supply 6 and when the receiving means does not receive the signal of specific frequency, the distributed power supply 6 is disconnected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for connecting and disconnecting a commercial power supply system and a distributed power supply, and particularly to a commercial power supply system side by an independent operation of the distributed power supply when power supply from the commercial power supply system is stopped. The present invention relates to a system interconnection operation control system for distributed power sources that can reliably prevent reverse power flow.

[0002]

2. Description of the Related Art Conventionally, in the interconnection operation of a commercial power supply system and a distributed power supply that allows reverse power flow from the distributed power supply to the commercial power supply system, a predetermined time has elapsed since the commercial power supply system was established. And the voltage and frequency of the commercial power supply system are within a predetermined range, the operation disconnection between the commercial power supply system and the distributed power supply is performed when the system voltage or frequency during the interconnection operation is within the predetermined range. It was done on the condition that it was outside.

The purpose of performing such control is to stop the power supply when the commercial power supply system is stopped due to an accident or the like.
When the distributed power source continues to operate independently, electric power is supplied from the distributed power source side to the commercial power system side to prevent the expansion of accident points and the hindrance of accident processing.

[0004]

The above-mentioned conventional method has the following problems. (B) When the power supply from the commercial power system is stopped while the rotating machine such as an electric motor is connected to the load when the commercial power system and the distributed power supply are in interconnection operation, the rotation of the rotating machine will take some time due to inertia due to inertia. continue. In this case, the rotating machine functions as a generator, and the generated voltage may be very similar to the voltage of the commercial power supply system, so it cannot be detected by the isolated operation detection method of the distributed power supply by voltage or frequency monitoring. There's a problem.

(B) As a result, electric power is supplied from the distributed power source side to the rotating machine load and the commercial power source system side, which leads to the spread of the accident in the case of a system accident and the personal injury of the maintenance personnel in the case of system maintenance. become.

(C) As a countermeasure against this, there is a method of increasing the sensitivity of voltage and frequency monitoring to detect even a slight fluctuation, but if this kind of detection method is adopted, even a normal fluctuation is erroneously detected. It will be.

(D) As a result, even in the case of normal voltage fluctuations and frequency fluctuations that may continue the interconnection operation of the commercial power supply system and the distributed power source, the interconnection operation is often disconnected. Furthermore, by irregularly repeating the disconnection with the grid connection, unnecessary power fluctuations are given to the commercial power system side, leading to a decrease in power supply stability, and the power supply from distributed power sources is reduced. As a result, there are problems such as a decrease in operating rate and a decrease in service life due to frequent operation of the interconnection / disconnection switch, and there is a limit to increasing the sensitivity of voltage and frequency monitoring.

(E) Recently, paying attention to the occurrence of a peculiar phenomenon such as a sudden change in the voltage phase when an isolated operation of the distributed power source occurs, and when the peculiar phenomenon is detected, the parallel operation is disconnected. Before the operation, only the operation of the distributed power supply is temporarily stopped, and the presence or absence of the power supply stoppage from the commercial power supply system is confirmed by the voltage or frequency monitoring.

However, even with such a method, the phenomenon due to the change in the power factor of the load and the total interference with other distributed type power sources operating in parallel is very similar to the phenomenon when the isolated type power source operation occurs. It turns out that there is a problem similar to (d),
After all, it is difficult to reliably detect only islanding.

Further, there are problems that the cost of the device increases with the expansion of the function, the device becomes large, and the maintenance becomes complicated. The present invention has been made to solve the above-mentioned problems, and a system interconnection operation control system for distributed power sources that can reliably disconnect the distributed power source from the commercial power source system when the commercial power source system stops. Is intended to provide.

[0011]

According to a first aspect of the present invention, there is provided a system interconnection control system for a distributed power source, a signal superimposing means for superimposing a predetermined frequency signal on a commercial power source of a commercial power source system under a predetermined condition, and a commercial power source. An opening / closing means for interconnecting the power supply system and the distributed power supply, a receiving means for receiving a predetermined frequency signal superimposed on the commercial power supply system, and a control means for controlling the opening / closing of the opening / closing means by the received signal are provided. It is composed of a system interconnection protection device. Therefore, the interconnection operation of the commercial power system and the distributed power source and the interconnection disconnection control can be carried out depending on whether or not the predetermined frequency signal superimposed on the commercial power source is received.

According to a second aspect of the present invention, there is provided a system interconnection control system for a distributed power source according to the first aspect, wherein the interconnection switch is controlled by the receiving means of the system interconnection protection device receiving a predetermined frequency signal. It is configured to perform the close control with the presence and the open control without receiving the predetermined frequency signal. As a result, the system interconnection operation can be safely performed.

According to a third aspect of the present invention, there is provided a system interconnection control system for a distributed power supply according to the first aspect, in which the interconnection switch is controlled because the receiving means of the system interconnection protection device does not output a predetermined frequency signal. When it is received that the presence is present, the closing control is performed after a predetermined time has elapsed, and when the presence of the predetermined frequency signal is received, the open control is instantaneously performed.

Therefore, when there is no received signal and when there is a received signal, grid interconnection can be started after a predetermined time required for the power supply of the commercial power source system to stabilize, and when there is no received signal, the distributed power source shifts to the commercial power source system side. To prevent unnecessary power supply, it is possible to immediately disconnect the interconnected operation.

According to a fourth aspect of the present invention, in the system interconnection control system for distributed power sources according to the first aspect, the predetermined frequency signal superimposed via the signal superimposing means is a signal having a different frequency for each commercial power source system. Configured to be. As a result, it is possible to control the grid disconnection between the commercial power supply system and the distributed power supply for each commercial power supply system.

According to a fifth aspect of the present invention, in the system interconnection control system for distributed power sources according to the first aspect, the predetermined frequency signals to be superposed via the signal superimposing means are plural for one commercial power source system. It was configured to be signals of different frequencies. As a result, it is possible to start and continue the distributed system interconnection with the commercial power system only when a plurality of predetermined frequency signals are received.

According to a sixth aspect of the present invention, in the system interconnection control system for distributed power sources according to the first aspect, the predetermined frequency signal superimposed via the signal superimposing means has no abnormality in the commercial power source system and is abnormal. It is configured to start the superimposition on the condition that a predetermined time has passed since the disappearance. As a result, it is possible to perform grid interconnection and disconnection control regardless of whether or not the commercial power system is supplied with power.

According to a seventh aspect of the present invention, in the system interconnection control system for distributed power sources according to the first aspect, the predetermined frequency signal superimposed via the signal superimposing means causes the commercial power system to transmit or cut off the power. Therefore, it was configured to send or stop sending to the commercial power supply system according to the opening and closing of the circuit breaker installed in the substation. As a result, system interconnection is automatically possible depending on whether the circuit breaker is opened or closed.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of a system interconnection control system for distributed power sources according to claim 1 of the present invention will be described with reference to FIG. Reference numeral 1 denotes a commercial power supply, which is connected to the signal superposing means 2 and also connected to the load 5 via the commercial power supply system 4.

On the other hand, the distributed power source 6 is connected to the commercial power source system 4 via the interconnection switch 7. Also, commercial power supply system 4
Is connected to the input of the receiving means 8a of the grid interconnection protection device 8,
The output of the receiving means 8a is connected to the input of the control means 8b, and the output of the control means 8b is connected as an opening / closing control signal of the interconnection switch 7.

The operation of the system interconnection control system for distributed power sources according to claim 1 of the present invention will be described. First, in FIG.
A predetermined frequency signal F is supplied to the commercial power source 1 by the signal superposing means 2.
s is superimposed and input to the receiving means 8a of the grid interconnection protection device 8 via the commercial power supply system 4.

The receiving means 8a detects the predetermined frequency signal Fs from the input commercial power source 1 and passes it as an input to the control means 8b. The control means 8b outputs a predetermined opening / closing control output to the interconnection switch 7 depending on the presence or absence of the predetermined frequency signal Fs.

According to the above-described embodiment, when the commercial power supply system 4 and the distributed power supply 6 are interconnected and the interconnected operation is released, is the predetermined frequency signal Fs superimposed on the commercial power supply 1 supplied from the commercial power supply system 4? It can be implemented by a simple method of whether or not.

The configuration of an embodiment of the system interconnection protection device 8 applied to the system interconnection control system for distributed power sources according to claim 2 of the present invention will be described with reference to FIG. The commercial power supply system 4 is connected to the input of the receiving means 8a of the system interconnection protection device 8, the output of the receiving means 8a is connected to the input of the control means 8b, and the control means 8b.
It has already been described that the output of is connected as the switching control signal of the interconnection switch 7.

The operation of the system interconnection protection device 8 applied to the system interconnection control system for distributed power sources according to claim 2 of the present invention will be described. First, the commercial power source on which the predetermined frequency signal Fs is superimposed is input to the receiving means 8a of the grid interconnection protection device 8.

The receiving means 8a detects the presence or absence of the predetermined frequency signal Fs from this input and passes it as an input to the control means 8b. The control means 8b outputs a close control output to the interconnection switch 7 when the predetermined frequency signal Fs is present, and outputs an open control output to the interconnection switch 7 when the predetermined frequency signal Fs is not present.

According to the above embodiment, the interconnection operation can be started or continued only when the predetermined frequency signal Fs is present. According to this method, the grid interconnection operation is canceled without the predetermined frequency signal Fs in any case, so that the grid interconnection operation can be controlled more safely.

The configuration of an embodiment of the system interconnection protection device 8 applied to the system interconnection control system for distributed power sources according to claim 3 of the present invention will be described with reference to FIG. The commercial power supply system 4 is connected to the input of the receiving means 8a of the system interconnection protection device 8.

The output of the receiving means 8a is connected to the input of the operation delay means 8c, the output of the operation delay means 8c is connected to the input of the control means 8b, and the output of the control means 8b is the opening / closing control of the interconnection switch 7. It is configured to be connected as a signal.

The operation of the system interconnection protection device 8 applied to the system interconnection control system for distributed power sources according to claim 3 of the present invention will be described with reference to FIG. First, the commercial power source on which the predetermined frequency signal Fs is superimposed is input to the receiving means 8a of the grid interconnection protection device 8. The receiving means 8a detects the presence or absence of the predetermined frequency signal Fs from this input, and passes it as the input of the operation delay means 8c.

The operation delay means 8c controls the control means 8b after a lapse of a predetermined time when the predetermined frequency signal Fs changes from none to present.
When the predetermined frequency signal Fs changes from the presence to the absence, the output is instantaneously passed to the control means 8b. Control means 8b
Outputs a close control output to the interconnection switch 7 when the predetermined frequency signal Fs is present, and outputs an open control output to the interconnection switch 7 when the predetermined frequency signal Fs is not present.

According to the above embodiment, the predetermined frequency signal Fs
The interconnection operation can be started and continued only when it has been present for a predetermined time or more since it was not present. According to this method, in any case, when the predetermined frequency signal Fs is present or absent, the grid interconnection operation is instantly released, so that more stable and safe control of the grid interconnection operation can be implemented.

The configuration of an embodiment of the predetermined frequency signal superimposing method applied to the system interconnection control system for distributed power sources according to claim 4 of the present invention will be described with reference to FIG. The commercial power supply 1 is connected to inputs of a filter 9 and a filter 19 that block a predetermined frequency, and signal superimposing means 2 and signal superimposing means 12 are connected to the outputs of the filter 9 and the filter 19, respectively. It is configured to be connected to the commercial power supply system 14.

The operation of the predetermined frequency signal superimposing method applied to the system interconnection control system for distributed power sources according to claim 4 of the present invention will be described. First, the commercial power supply 1 passes through the filter 9 and the filter 19 and then the signal superposing means 2 for the predetermined frequency signal Fa.
The predetermined frequency signal is superimposed by the signal superimposing means 12 for the predetermined frequency signal Fb and the commercial power supply system 4 and the commercial power supply system 14.
Sent to.

Here, the filters 9 and 19 are filters provided to prevent the predetermined frequency signals sent from the signal superposing means 2 and the signal superposing means 12 from flowing out to the other side via the commercial power source 1 side. .

According to the above-described embodiment, the commercial power supply system 4 and the commercial power supply system 14 can separately control the distributed power supply and the interconnecting operation and the disconnection of the interconnecting operation. Therefore, it is possible to always limit the distributed power sources that can be interconnected to the specified commercial power source system to the distributed type power sources of its own system, so that even in the case of a complicated commercial power source system, management can be easily performed. It becomes possible.

The configuration of an embodiment of the predetermined frequency signal superimposing method applied to the system interconnection control system for distributed power sources according to the fifth aspect of the present invention will be described with reference to FIG. The commercial power supply 1 includes a plurality of signal superimposing means, for example, the signal superimposing means 2 and the signal superimposing means.
12 and the signal superimposing means 22 and the commercial power supply system 4.

The operation of the predetermined frequency signal superimposing method applied to the system interconnection control system for distributed power sources according to claim 5 of the present invention will be described. First, in the commercial power source 1, a predetermined frequency signal F is generated by the signal superimposing means 2, the signal superimposing means 12, and the signal superimposing means 22.
a, Fb, and Fc are superimposed and sent to the commercial power supply system 4.

According to the above-described embodiment, the interconnection operation of the commercial power source system 4 and the distributed power sources connectable to the commercial power source system 4 and the cancellation of the interconnection operation can be performed for each of the predetermined frequency signals Fa, Fb, Fc. it can. Therefore, it is possible to individually select the distributed power sources that are connected to the commercial power source system or select only the limited areas, and it becomes easy to manage even in the case of a complicated commercial power source system.

The configuration of an embodiment of the predetermined frequency signal superimposing method applied to the system interconnection control system for distributed power sources according to claim 6 of the present invention will be described with reference to FIG. The commercial power source 1 is connected to the signal superimposing means 2 as well as to the commercial power source system 4, and the signal superimposing means 2 is connected to the signal superimposing control means 10.

The operation of the predetermined frequency signal superimposing method applied to the system interconnection control system for distributed power sources according to claim 6 of the present invention will be described. First, whether or not to superimpose the predetermined frequency signal Fs on the commercial power source 1 by the signal superimposing means 2 is determined by a signal superimposing control command from the signal superimposing controlling means 10.

The signal superimposing control means 10 is provided on the condition that a predetermined time has elapsed, that the commercial power supply system has no trouble such as an accident, and that there is no problem in operating the distributed power supply in an interconnected manner. The signal superimposition instruction is output to No. 2, and when these conditions are not satisfied, the signal superimposition instruction is stopped.

According to the above-described embodiment, it is possible to arbitrarily control whether or not the predetermined frequency signal Fs is superimposed on the commercial power source 1. Therefore, the start and cancellation of the interconnection operation of the commercial power system and the distributed power source can be finely set. It becomes possible to do.

An embodiment of a predetermined frequency signal superimposing method applied to the system interconnection control system for distributed power sources according to claim 7 of the present invention will be described with reference to FIG. The commercial power source 1 is connected to the signal superimposing means 2 and also connected to the commercial power source system 4 via the circuit breaker 3, and the commercial power source system 4 is connected to the load 5.

On the other hand, the distributed power source 6 is connected to the commercial power source system 4 via the interconnection switch 7. The commercial power system 4 is connected to the input of the receiving means 8a of the system interconnection protection device 8, and the output of the receiving means 8a is connected to the input of the control means 8b.
The output of 8b is connected as an open / close control signal for the interconnection switch 7.

The operation of the predetermined frequency signal superimposing method applied to the system interconnection control system for distributed power sources according to claim 7 of the present invention will be described. First, in FIG. 7, the predetermined frequency signal Fs is superimposed on the commercial power source 1 by the signal superimposing means 2. When the circuit breaker 3 is closed in this state, commercial power is supplied to the commercial power system 4, so that the predetermined frequency signal Fs is also sent to the commercial power system 4.

Therefore, the receiving means 8a of the grid interconnection protection device 8 which operates by using the commercial power source of the commercial power source system 4 as an input receives the predetermined frequency signal Fs and passes the output with the received signal as the input of the control means 8b. The control means 8b determines that the system interconnection condition is satisfied from the presence of the received signal, and outputs an output for controlling to close the system interconnection switch 7.

By closing the system interconnection switch 7, the commercial power supply system 4 and the distributed power supply 6 are in an interconnected operating state, and the load 5 connected to the commercial power supply system is connected to the commercial power supply 1 and the distributed power supply 6. Power can be supplied from both sides.

In this state, when the circuit breaker 3 opens, the commercial power supply system 4 is temporarily supplied with power from the distributed power supply 6. However, since the predetermined frequency signal Fs is not superimposed on the electric power supplied from the distributed power source 6, the grid interconnection protection device 8 that operates by using the commercial power source of the commercial power source system 4 as an input.
The receiving means 8a of FIG. 2 cannot receive the predetermined frequency signal Fs, and passes the output without the received signal as the input of the control means 8b.

Since there is no received signal, the control means 8b judges that the system interconnection condition is not satisfied, and outputs an output for controlling the system interconnection switch 7 to open. When the system interconnection switch 7 is opened, the interconnection operation state of the commercial power source system 4 and the distributed power source 6 is released, and the power supply to the load connected to the commercial power source system is stopped.

According to the above-described embodiment, the interconnection operation of the commercial power source system 4 and the distributed power source 6 and the release control of the interconnection operation can be performed in conjunction with the opening / closing operation of the circuit breaker 3.
Further, when the predetermined frequency signal Fs cannot be received regardless of the switching operation of the circuit breaker 3, the grid interconnection operation is canceled, so that the grid interconnection operation can be controlled more reliably and safely. You can

[0052]

As described above, according to the present invention, when the distributed power source is connected to or disconnected from the commercial power source system,
By performing control depending on whether or not a predetermined frequency signal is superimposed on the commercial power system, voltage fluctuation, frequency fluctuation, harmonic content, system disconnection, system short circuit, system ground fault, load fluctuation, etc. of the commercial power system Regardless of any change in the situation, it is possible to determine whether the power is supplied or stopped based on whether or not the predetermined frequency signal is received, so that reliable interconnection and disconnection control can be performed. In addition, the system interconnection protection device can realize the necessary functions only by the means for controlling the interconnection switch depending on the presence or absence of a predetermined frequency signal, so it is simpler than the conventional method, so a small and inexpensive product can be obtained. Can be supplied.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a system interconnection control system for distributed power sources according to claim 1 of the present invention.

FIG. 2 is a block diagram showing the configuration of an embodiment of a system interconnection protection device applied to the system interconnection control system for distributed power sources according to claim 2 of the present invention.

FIG. 3 is a block diagram showing a configuration of an embodiment of a system interconnection protection device applied to a system interconnection control system of a distributed power source according to claim 3 of the present invention.

FIG. 4 is a block diagram showing the configuration of an embodiment for explaining a predetermined frequency signal superimposing method applied to the system interconnection control method for distributed power sources according to claim 4 of the present invention.

FIG. 5 is a block diagram showing the configuration of an embodiment for explaining a predetermined frequency signal superimposing method applied to the system interconnection control system for distributed power sources according to claim 5 of the present invention.

FIG. 6 is a block diagram showing the configuration of an embodiment for explaining a predetermined frequency signal superimposing method applied to the system interconnection control system for distributed power sources according to claim 6 of the present invention.

FIG. 7 is a block diagram showing the configuration of an embodiment for explaining a predetermined frequency signal superimposing method applied to the system interconnection control system for distributed power sources according to claim 7 of the present invention.

[Explanation of symbols]

 1 Commercial power source 2, 12, 22 Signal superimposing means 3 Circuit breaker 4 Commercial power source system 5 Load 6 Distributed power source 7 Interconnection switch 8 System interconnection protection device 8a Receiving means 8b Control means 8c Operation delaying means 9,19 Filter

Claims (7)

[Claims] 1. A distributed power source connected to a commercial power supply system through an opening / closing means, and a system interconnection protection device for controlling the opening / closing of the opening / closing means by inputting a voltage and a current supplied from the commercial power supply system. In the configured power supply system, a signal superimposing means for superimposing a predetermined frequency signal on the power source side of the commercial power supply system is provided, and a receiving means for receiving the predetermined frequency signal in the grid interconnection protection device and the received signal And a control means for controlling the opening / closing of the opening / closing means. 2. The control of the switch for interconnection is closed by the receiving means of the system interconnection protection device when the predetermined frequency signal is received,
2. The system interconnection control system for distributed power sources according to claim 1, wherein the open control is performed without receiving a predetermined frequency signal. 3. The control of the interconnection switch is such that, when the receiving means of the system interconnection protection device receives the predetermined frequency signal from the absence to the presence, the close control is performed after a predetermined time elapses, and the predetermined frequency signal is turned on. When I receive the message that it is changed from yes to no,
2. The system interconnection operation control system for distributed power sources according to claim 1, wherein the open control is performed instantaneously. 4. The system interconnection control system for distributed power sources according to claim 1, wherein the predetermined frequency signal to be superimposed via the signal superimposing means is a signal having a different frequency for each commercial power system. . 5. The distributed power supply system according to claim 1, wherein the predetermined frequency signal to be superimposed via the signal superimposing means is a signal having a plurality of different frequencies with respect to one commercial power supply system. Interconnected operation control method. 6. The predetermined frequency signal to be superposed via the signal superimposing means has no abnormality in the commercial power supply system, and superimposition is started on condition that a predetermined time has elapsed after the abnormality has disappeared. 2. The system interconnection operation control system for distributed power sources according to claim 1. 7. The predetermined frequency signal to be superposed via the signal superimposing means is sent to the commercial power supply system or stopped to be sent to the commercial power supply system in response to opening and closing of a circuit breaker provided in a substation for transmitting or cutting off power to the commercial power supply system. Claim 1 characterized by the above.
The system operation control system for the distributed power sources described.