JPH06153405A - Customer power source islanding prevention device or islanding prevention method - Google Patents

Abstract

(57) [Summary] [Purpose] It is to prevent the customer power supply installed in the power customer who supplies power from the substation from operating independently. [Structure] Even if the transmission breaker that sends electric power from the substation to the electric power consumer is open, if the voltage exists on the load side of this transmission breaker, the consumer power supply operates independently. Therefore, an artificial ground fault accident occurs on the load side of this transmission breaker. This ground fault is detected by the customer power supply side, and the customer power supply is disconnected from the power distribution system to prevent islanding. Here, the artificial ground fault is a one-wire ground fault, a three-wire ground fault, or a combination of both, until the load-side voltage of the output circuit breaker becomes zero (that is, until the customer power supply is disconnected from the distribution system). ) Repeated ground faults will occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a customer who can avoid the risk of the customer power supply operating independently even if the substation cuts off the power distribution system while the distribution system and the customer power supply are operating in parallel. The present invention relates to an islanding prevention device or an islanding prevention method for a power source.

[0002]

2. Description of the Related Art Even a thermal power plant of a million kilowatt class has a power generation efficiency of slightly over 40%, and the remaining 60% or less of energy is discarded as heat into the atmosphere or cooling water. It's closed. The power generation efficiency of a power generation facility with a smaller capacity than this, for example, a 1,000 kilowatt class engine power generation facility is even smaller, generally 30% or less, and 70% of energy is discarded without being used, which is extremely uneconomical. . Therefore, in urban areas, power generation facilities with this level of output are often installed for emergency use, and there was almost no continuous operation. However, if the heat generated during power generation and wasted in the past is also used at the same time, the total thermal efficiency will be as high as 70 to 80%. Therefore, consumers such as office buildings and department stores that consume a large amount of heat together with electric power have a lower energy cost than purchasing only electric power, and thus such equipment has been introduced more often. Such equipment that also uses heat generated together with electric power at the same time is generally called cogeneration equipment.

FIG. 12 is a single-line circuit diagram showing a conventional example of a power distribution system for supplying electric power from a substation to an electric power consumer equipped with a consumer power source. In FIG. 12, the substation 10
The electric power input to the transformer 3 is transformed by the transformer 3 via the power receiving circuit breaker 2 and passes through the first circuit breaker 11, the second circuit breaker 21, and the third circuit breaker 31 provided as the transmission circuit breakers on the bus bar 4. Power to each power consumer. That is, from the first circuit breaker 11 to the first customer 13 as a power consumer via the power distribution system 12, from the second circuit breaker 21 to the second customer 23 as a power consumer via the power distribution system 22, From the third circuit breaker 31 through the power distribution system 32 to the third
Electric power is being sent to the customer 33.

The first customer 13 is composed of an input circuit breaker 14, a first load 15 and a first power source 16 as shown in the figure.
If the first customer 13 is provided with the cogeneration equipment as described above, the energy cost can be reduced. Therefore, the first power supply 16 as the cogeneration equipment is provided and the first power supply 16 is used as the power distribution system 12. And run in parallel. The first load 15 is supplied with electric power from the first power supply 16, but only the electric power that is still insufficient is received from the substation 10. The first power source 16 is a cogeneration facility as described above, but the heating portion is not related to the present invention, so the illustration is omitted and only the generator portion is shown. If a fuel cell is used instead of the engine power generation facility, hot water is generated together with the generation of electric power (DC power is converted into AC power by an inverter), so that it becomes a cogeneration facility.

Similarly, the second consumer 23 also comprises an input circuit breaker 24, a second load 25 and a second power source 26, and the second power source 26 is a cogeneration facility. However, the third customer 33 does not have a customer power supply, and the input circuit breaker 34
And the third load 35 only. In the conventional example circuit of FIG. 12, the first power source 16 and the second power source 26 in the first consumer 13 and the second consumer 23 operate in parallel with their respective distribution systems. Therefore, for example, when an abnormality occurs in the first power supply 16, unless the power is immediately disconnected from the distribution system, the distribution system is disturbed and the substation 1
0, and the second consumer 23 and the third consumer irrelevant to the abnormality are
There is a risk that the customer 33 will be cut off. Therefore, it is obligatory to install protection relays for overcurrent protection, overvoltage protection, reverse current protection, ground fault protection, etc. in the customer power supply.If an abnormality occurs in the customer power supply, disconnect it from the power distribution system promptly. You can do it.

[0006]

While the substation 10 is supplying electric power to each customer, for example, if an internal accident such as a failure of the transformer 3 occurs, the power receiving circuit breaker 2 trips. Since the first circuit breaker 11, the second circuit breaker 21, and the third circuit breaker 31 also trip, the voltage of the power distribution system 12, the power distribution system 22, and the power distribution system 32 should be zero. However, in the case where the first customer 13 is operating the first power supply 16 at the time of the in-house accident and the power generated by the first power supply 16 and the power consumption of the first load 15 are substantially balanced, Means that even if the first circuit breaker 11 trips, the first power source 16 keeps the first circuit
Power may be continuously supplied to the load 15, and at this time, the distribution system 12 is in a charged state.

As described above, even if the electric power from the substation 10 to the distribution system 12 is cut off, the phenomenon that the first power supply 16 as a consumer power supply continues to operate and charges the distribution system 12 is operated independently. However, there is a risk of electric shock because the load side of the first circuit breaker 11 is charged even though the first circuit breaker 11 is opened by the independent operation of the first power supply 16. Therefore, it is required as a system linkage technical requirement to install a device for preventing an independent operation in a power source for a customer such as a cogeneration facility. However, as described above, the conventional islanding prevention device may not operate depending on the system conditions.

Therefore, an object of the present invention is to prevent a customer power supply installed in a power customer who supplies power from a substation from operating independently.

[0009]

In order to achieve the above-mentioned object, a consumer power supply islanding prevention device or an islanding prevention method according to the present invention is an electric power configured by connecting a load and a customer power source in parallel. In a power system configured to supply power to a consumer via a transmission breaker that transmits power from a substation and a distribution system, a voltage that detects the presence or absence of the voltage of the distribution system on the load side of the transmission breaker. A detection unit and a one-line ground fault unit for generating a one-line ground fault condition in the distribution system for a certain period of time;
If a voltage exists in the power distribution system when the delivery breaker is off, the first islanding prevention device configured by the operation command means for giving an operation command to the one-line ground fault means is the delivery breaker. Or a voltage detecting means for detecting the presence or absence of voltage in the distribution system,
If there is a voltage in the three-wire ground fault means for generating a wire-ground fault condition for a certain period of time and the distribution system when the delivery breaker is off, an operation command for giving an operation command to the three-wire ground fault means. Or a voltage detection means for detecting the presence or absence of voltage in the distribution system, and a one-line ground fault means for generating a one-line ground fault condition in the distribution system for a certain period of time. A three-wire ground fault means for generating a three-wire ground fault condition in the power distribution system for a certain period of time; and a one-wire ground fault device if a voltage exists in the power distribution system when the delivery breaker is off. It is provided with a third islanding operation preventing device configured to give an operation command and an operation command means for giving an operation command to the three-wire ground fault means if a voltage exists in the distribution system at this point, or these first independent operation prevention devices are provided. Driving prevention device or second islanding prevention device or 3 alone driving preventing device power distribution system voltage is assumed to repeatedly operate until zero.

[0010]

The present invention focuses on the fact that the customer power supply is always provided with a ground fault detection relay that disconnects the customer power supply from the power distribution system to prevent the system from being disturbed if a ground fault is detected. However, despite the fact that the transmission circuit breaker that transmits electric power from the substation to the electric power consumer is open,
If a voltage exists on the load side of the delivery breaker, it is determined that the consumer power supply is operating independently, and an artificial ground fault occurs on the load side of the delivery breaker. This ground fault is detected on the customer power supply side and the customer power supply is disconnected from the power distribution system, so islanding is prevented. Here, the artificial ground fault is a one-wire ground fault, a three-wire ground fault, or a combination of both, until the load-side voltage of the output circuit breaker becomes zero (that is, until the customer power supply is disconnected from the distribution system). ) Repeated ground faults will occur.

[0011]

FIG. 1 is a single-line circuit diagram showing a basic embodiment of the present invention. The power receiving circuit breaker 2 shown in FIG.
Transformer 3, bus bar 4, first circuit breaker 1 as a transmission circuit breaker
1, distribution system 12, first consumer 1 as a power consumer
3, input circuit breaker 14, first load 15, first power supply 16, second circuit breaker 21 as a delivery circuit breaker, distribution system 22, second consumer 23 as a power consumer, input circuit breaker 24, second
Names, uses, and functions of the load 25, the second power supply 26, the third circuit breaker 31 as a delivery circuit breaker, the power distribution system 32, the third customer 33 as an electric power consumer, the input circuit breaker 34, and the third load 35. 12 is the same as that of the conventional circuit described above with reference to FIG.

According to the present invention, the islanding prevention device 41 is provided on each of the load breakers of the first breaker 11 and the second breaker 21 for sending electric power to the electric power consumer equipped with the consumer power supply. And the islanding prevention device 42 are separately connected, and when the islanding fault occurs in the power distribution system by the islanding prevention device 41 or 42, and the substation 40 has a power failure, the first power source 16 or the second power source 26. To prevent it from operating independently. In the following, the islanding prevention device 41 for preventing the first power source 16 provided in the first consumer 13 from operating alone will be described.
Since 2 has the same configuration as this, its description is omitted.

It should be noted that the islanding prevention device 41 is constituted by either the first islanding operation preventing device 50, the second islanding operation preventing device 60, or the third islanding operation preventing device 70, as will be described below. To do. Similarly, the islanding prevention device 42 is also configured by either the first islanding prevention device 50, the second islanding prevention device 60, or the third islanding prevention device 70.

FIG. 2 is an external view showing the configuration of a first islanding prevention device which is the first embodiment of the present invention, and corresponds to the islanding prevention device 41 shown in the basic circuit of FIG. It is a thing. The first embodiment of FIG. 2 corresponds to claim 1, and the first islanding prevention device 50 shown in the drawing is the distribution system 1
2 system voltage measuring device 51 for measuring the presence or absence of voltage, 1-line ground fault device 52 for artificially generating a 1-line ground fault condition in this distribution system 12 for a certain period of time, system voltage measuring device 51 and 1-line ground First operation command circuit 53 for giving an operation command to the relay device 52
It consists of and.

FIG. 3 is a first flow chart showing the operation of the first embodiment shown in FIG. 2, and also corresponds to claim 1. In this first flow chart, the first circuit breaker 11
Is determined to be off or on by determination 81, and if it is off, processing 91 determines power distribution system 12
The voltage is measured, and the judgment 82 judges the presence or absence of the voltage. If the input circuit breaker 14 is also off when the first circuit breaker 11 is off, the voltage is not applied to the distribution system 12 even when the first power supply 16 is operating, and the voltage is zero. If the circuit breaker 14 is turned on during operation and the power distribution system 12 is charged, the presence of voltage is detected. Therefore, if the determination 82 determines that there is a voltage, the one-line ground fault device 52 is activated by the process 92, so that the artificial one-line ground fault state continues for a certain period of time. Due to this artificial 1-line ground fault condition, the ground fault detection relay equipped in the first power source 16 operates to disconnect the first power source 16 from the power distribution system 12, that is, the input circuit breaker 14 is turned off. Because the operation is done, the first
The independent operation of the power supply 16 can be avoided.

FIG. 4 is a second flow chart showing a second embodiment of the present invention showing the operation when the first islanding prevention device shown in FIG. 2 is used, and corresponds to claim 2.
The functions of the judgments 81 and 82 and the processes 91 and 92 shown in the second flow chart are the same as those in the case of the first flow chart described above with reference to FIG.
In this second flowchart, the voltage of the power distribution system 12 after the one-line ground fault device 52 is operated in the process 92 is measured in the process 93, and if the judgment 83 judges that there is a voltage, the power distribution system 1
The operation of the one-wire ground fault device 52 and the voltage detection by the system voltage measuring device 51 are repeated until the voltage of 2 becomes zero.

FIG. 5 is an external view showing the configuration of a second islanding prevention device which is a third embodiment of the present invention, and corresponds to the islanding prevention device 41 shown in the basic circuit of FIG. It is a thing. The third embodiment of FIG. 5 corresponds to claim 3, and the illustrated second islanding prevention device 60 includes a system voltage measuring device 51 for measuring the presence or absence of voltage in the distribution system 12, and artificial distribution. A three-wire ground fault device 62 for generating a three-wire ground fault condition in the system 12 for a certain period of time, and these system voltage measuring devices 51 and 3
The line-to-ground fault device 62 and the second operation command circuit 63 that gives an operation command.

FIG. 6 is a third flow chart showing the operation of the third embodiment shown in FIG. 5, and also corresponds to claim 3. In this third flowchart, if the judgment 82 judges that there is a voltage, the process 94 operates the three-wire ground fault device 62, which is a point different from the first flowchart described above in FIG. And 82 and the function of the process 91 are the same as in the case of the first flow chart, and therefore their explanation is omitted.

FIG. 7 is a fourth flowchart showing a fourth embodiment of the present invention showing the operation when the second islanding prevention device shown in FIG. 5 is used, and corresponds to claim 4.
This fourth flow chart has a configuration in which the processing 95 and the determination 84 are added to the third flow chart described in FIG. 6, and the three-wire ground fault device 62 is operated in the processing 94 and then the power distribution system is processed in the processing 95. The voltage of 12 is measured, and if the determination 84 determines that there is a voltage, the operation of the three-wire ground fault device 62 and the voltage detection by the system voltage measuring device 51 are repeated until this voltage becomes zero.

FIG. 8 is an external view showing the configuration of the third islanding prevention device which is the fifth embodiment of the present invention, and corresponds to the islanding prevention device 41 shown in the basic circuit of FIG. It is a thing. The fifth embodiment of FIG. 8 corresponds to claim 5, and the third islanding prevention device 60 includes a system voltage measuring device 51 for measuring the presence or absence of voltage in the distribution system 12, and this distribution system artificially. A 1-line ground fault device 52 for generating a 1-line ground fault condition for 12 hours for a certain period of time, as well as artificially
A three-wire ground fault device 62 for generating a linear ground fault condition for a certain period of time,
A third operation command circuit 73 that gives an operation command to the system voltage measuring device 51, the one-line ground fault device 52, and the three-line ground fault device 62.
It consists of and.

FIG. 9 is a fifth flowchart showing the operation of the fifth embodiment shown in FIG. 8, and also corresponds to claim 5. This fifth flow chart has a configuration in which the first flow chart described above with reference to FIG. 3 and the third flow chart described above with reference to FIG. If the determinations 81 and 82 determine that there is a fault, first, in a process 91, the 1-line ground fault device 52
However, if the determination 83 still determines that there is voltage, the three-wire ground fault device 62 is operated in step 94.

FIG. 10 is a sixth flow chart showing a sixth embodiment of the present invention showing the operation when the third islanding prevention device shown in FIG. 8 is used, and corresponds to claim 6. The sixth flowchart has a configuration in which the process 95 and the determination 84 are added to the fifth flowchart described above in FIG. 9, and the three-wire ground fault device 62 is operated in the process 94 and then the power distribution system 12 is processed in the process 95. If the determination 84 determines that there is a voltage, the operation of the three-wire ground fault device 62 and the voltage detection by the system voltage measuring device 51 are repeated until the voltage becomes zero.

FIG. 11 is a seventh flow chart showing a seventh embodiment of the present invention showing an operation when the third islanding prevention device shown in FIG. 8 is used, and corresponds to claim 7. Although the configuration of the seventh flowchart is the same as the configuration of the sixth flowchart described above with reference to FIG. 10, the three-wire ground fault device 62 is operated in process 94 and then the power distribution system 12 is processed in process 95.
If the determination 84 determines that there is a voltage, the 1-line ground fault device 52 is first operated to detect the voltage by the system voltage measuring device 51 until the voltage becomes zero, and then 3
The line-to-ground fault device 62 is operated to repeatedly perform voltage detection by the system voltage measuring device 51.

[0024]

[Effects of the Invention] When power is supplied from a substation to a power consumer equipped with a customer power supply through a distribution system, the transmission breaker for sending power to the distribution system is shut off due to a failure of the substation or the like. However, if the customer power supply is in the isolated operation state, the load side of the output circuit breaker remains charged and there is a danger of electric shock, which is extremely dangerous in the past. It was difficult to do. However, in the present invention, if the islanding prevention device is installed on the load side of the transmission circuit breaker of the substation, that is, on the distribution system, and if the voltage exists in the distribution system despite the fact that the transmission circuit breaker is off, this will occur. It is determined that the consumer power supply is in the independent operation state, and this power distribution system artificially causes the one-line ground fault state or the three-line ground fault state. Since the customer power supply must always have the ground fault detection relay installed, the artificial power supply is detected and the customer power supply is disconnected from the power distribution system, so that the isolated operation can be reliably avoided. Furthermore, this artificial 1-wire ground fault or 3-wire ground fault is repeatedly performed until the voltage of the distribution system becomes zero so that the malfunction of the ground fault detection relay of the customer power supply can be dealt with. Driving can be avoided more reliably.

[Brief description of drawings]

FIG. 1 is a single-line circuit diagram showing a basic embodiment of the present invention.

FIG. 2 is an external view showing the configuration of a first islanding prevention device that is a first embodiment of the present invention.

FIG. 3 is a first flowchart showing the operation of the first embodiment shown in FIG.

FIG. 4 is a second flowchart showing a second embodiment of the present invention, which shows the operation when the first islanding prevention device shown in FIG. 2 is used.

FIG. 5 is an external view showing the configuration of a second islanding prevention device which is a third embodiment of the present invention.

6 is a third flowchart showing the operation of the third embodiment shown in FIG.

FIG. 7 is a fourth flow chart showing a fourth embodiment of the present invention, which shows the operation when the second islanding prevention device shown in FIG. 5 is used.

FIG. 8 is an external view showing the configuration of a third islanding prevention device which is a fifth embodiment of the present invention.

FIG. 9 is a fifth flowchart showing the operation of the fifth embodiment shown in FIG.

FIG. 10 is a sixth flow chart showing a sixth embodiment of the present invention showing the operation when the third islanding prevention device shown in FIG. 8 is used.

FIG. 11 is a seventh flow chart showing a seventh embodiment of the present invention, showing the operation when the third islanding prevention device shown in FIG. 8 is used.

FIG. 12 is a single-line circuit diagram showing a conventional example of a distribution system that supplies electric power from a substation to an electric power customer equipped with a customer power supply.

[Explanation of symbols]

 2 Power receiving circuit breaker 3 Transformer 4 Bus 10 Substation 11 First circuit breaker as a transmission circuit breaker 12 Distribution system 13 First customer as a power consumer 14 Input circuit breaker 15 First load 16 First power supply 40 Transformer 41 41 islanding prevention device 50 1st islanding prevention device 51 system voltage measuring device 52 1-line ground fault device 53 1st operation command circuit 60 2nd islanding prevention device 62 3 wire ground fault device 63 2nd operation command circuit 70 Third islanding prevention device 73 Third operation command circuit 81 Judgment 82 Judgment 83 Judgment 84 Judgment 91 Processing 92 Processing 93 Processing 94 Processing 95 Processing

Claims (7)

[Claims] 1. A power system configured to supply power to a power consumer configured by connecting a load and a power source in parallel to a power consumer via a transmission breaker for transmitting power from a substation and a power distribution system. A voltage detecting means for detecting the presence or absence of voltage in the distribution system,
1-line ground fault means for generating a 1-line ground fault condition in the power distribution system for a certain period of time, and an operation command to the 1-line ground fault device if a voltage exists in the power distribution system when the delivery breaker is off. A first isolated operation preventing device configured with a first operation commanding means for providing a power supply to a consumer side, the isolated operation preventing device for a consumer power supply. 2. A power system configured to supply power to a power consumer configured by connecting a load and a power source in parallel to a power consumer via a transmission breaker for transmitting power from a substation and a power distribution system. If a voltage exists in the distribution system after the 1-line ground fault condition is generated for a certain period of time by the first islanding prevention device according to claim 1, the first islanding prevention is performed until the voltage disappears. A method for preventing an isolated operation of a customer power supply, which comprises repeatedly operating the device. 3. A power system configured to supply power to a power consumer, which is configured by connecting a load and a power source in parallel, to a power consumer via a transmission breaker for transmitting power from a substation and a power distribution system. A voltage detecting means for detecting the presence or absence of voltage in the distribution system,
3-wire ground fault means for generating a 3-wire ground fault condition in the power distribution system for a certain period of time, and an operation command to the 3-wire ground fault device if voltage exists in the power distribution system when the delivery breaker is off. A second islanding operation preventing device configured to provide a second operation commanding means for providing a power source to a consumer power source. 4. A power system configured to supply power to a power consumer configured by connecting a load and a power source in parallel to each other via a transmission breaker for transmitting power from a substation and a power distribution system. If a voltage exists in the distribution system after the three-wire ground fault condition is generated for a certain period of time by the second islanding prevention device according to claim 3, the second islanding prevention is performed until the voltage disappears. A method for preventing an isolated operation of a customer power supply, which comprises repeatedly operating the device. 5. A power system configured to supply power to a power consumer configured by a load and a power source connected in parallel to a power consumer via a transmission breaker for transmitting power from a substation and a power distribution system. A voltage detecting means for detecting the presence or absence of voltage in the distribution system,
A one-line ground fault means for generating a one-line ground fault condition in the power distribution system for a certain period of time, a three-wire ground fault device for generating a three-line ground fault condition in the power distribution system for a certain period of time, and the delivery breaker being turned off. If there is a voltage in the distribution system during the operation, an operation command is given to the one-line ground fault means, and if there is a voltage in the distribution system at this point, an operation command is given to the three-wire ground fault means.
An independent operation prevention device for a consumer power supply, comprising a third isolated operation prevention device configured with operation command means on the load side of the delivery breaker. 6. A power system configured to supply power to a power consumer configured by a load and a power source connected in parallel to a power consumer via a transmission breaker for transmitting power from a substation and a power distribution system. If a voltage exists in the distribution system after the three-wire ground fault condition is generated for a certain period of time by the third islanding prevention device according to claim 5, the third islanding prevention is performed until the voltage disappears. A method for preventing isolated operation of a customer power supply, characterized in that a three-wire ground fault means of the device is repeatedly operated. 7. A power system configured to supply power to a power consumer configured by connecting a load and a power source in parallel to a power consumer via a transmission breaker for transmitting power from a substation and a power distribution system. If a voltage exists in the distribution system after the three-wire ground fault condition is generated for a certain period of time by the third islanding prevention device according to claim 5, the third islanding operation is performed until the voltage disappears. The preventive device first activates the one-line ground fault means, and then repeats the operation of operating the three-line ground fault means.