JPH11299083A - Digital protective unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the required number of instrument transformers and instrument current transformers by sharing an instrument transformer or an instrument current transformer when the detecting points of circuit voltage or current required for a plurality of protective elements are identical. SOLUTION: An instrument current transformer CT1 detects the neutral current of a generator motor 1 and acts on a ground overcurrent relay element 51G. Instrument current transformers CT2, CT6 detect the zero-phase current of a generator motor main circuit and act on a ground differential relay element 87G. Instrument current transformers CT3, CT5 detect the main circuit current of the generator motor 1 and act commonly on a field missing relay element 40, overcurrent relay elements 51, 51B and power relay elements 91L, 91C in addition to a generator motor ratio proportional relay element 87. This arrangement minimizes the number of instrument current transformers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital protection device for detecting an electrical accident in a main circuit of a generator or a transformer and protecting the same.

[0002]

2. Description of the Related Art Many protection elements for protecting a generator are required, such as overcurrent protection, ratio differential protection, loss of field protection, overvoltage protection, and undervoltage protection. When configuring a protection system with analog relays such as induction disk or induction cylinder, the analog relays have a relatively large burden, so each analog relay must be equipped with an instrument transformer or an instrument current transformer. was there.

[0003] In recent years, analog relays have been successively replaced by digital protection devices. However, even in the configuration of the digital protection device, as in the conventional concept, there are provided as many meter transformers or meter current transformers as the number of protection elements. .

FIG. 4 shows a single-line connection diagram of a conventional digital protection device applied to protection of a generator motor and a main transformer of a pumped storage power plant.

In the pumped storage power plant, a generator motor 1 is connected to a transmission line via a parallel-circuit breaker 2, a phase sequence switching disconnector 3, a main transformer 4, and a high-voltage cable 5. The main circuit of the generator motor 1 and the main circuit of the main transformer 4 have a relatively large number of protection elements in a pumped storage power plant.
Three instrument current transformers CT1 to CT13 and three instrument transformers PT1 to PT3 are provided, and these instrument current transformers CT1 to CT13 and instrument transformers PT1 to PT3 are provided.
The secondary circuit of the PT 3 is connected to the protection element of the generator motor 1 and the protection element of the main transformer 3.

The protection elements of the generator motor 1 include an undervoltage relay element 27, a field loss relay element 40, an overcurrent relay element 51, and an overcurrent relay element (for electric brake) 5.
1B, ground fault overcurrent relay element 51G, overvoltage relay element 59, ground fault overvoltage relay element 64B, generator ratio differential relay element 87, ground fault differential relay element 87G, power relay element (for monitoring pumping input) 91L, power A relay element (for input monitoring during phase adjustment operation) 91C, a frequency relay element (for over-frequency monitoring) 95H, and a frequency relay element (for under-frequency monitoring) 95L are provided.

[0007] The protection elements of the main transformer 4 include:
A negative phase relay element 46, an overcurrent relay element 51T, a ground fault overcurrent relay element 51TG, a cable ratio differential relay element 87C, and a main transformer ratio differential relay element 87T are provided.

As shown in FIG. 4, even when the same current or voltage is detected, a current transformer CT or a transformer PT is provided for each protection element in principle. Although three to three protection elements are put together, a large number of current transformers CT and PTs for the entire plant are required.

Next, FIG. 5 is an explanatory diagram of a conventional digital protection device provided with a protection element and a failure detection element. The digital protection device includes a main protection device 6 and a failure detection device 6F. The main protection device 6 performs a protection operation based on the current and voltage detected by the current transformer CT and the transformer PT. The failure detection device 6F prevents runaway when the main protection device 6 fails.

The main protection device 6 comprises a main protection operation unit 9 composed of two or three protection elements, and a main protection input converter 7 for converting current and voltage to the protection elements into a predetermined signal level. , 8. FIG. 5 shows a combination of the overcurrent relay element 51 and the generator ratio operation relay element 87 as protection elements of the main protection calculation unit 9.

In the main protection device 6, main protection input converters 7 and 8 are provided for each protection element, and the outputs of the main protection input converters 7 and 8 are input to a main protection calculation unit 9. The main protection input converters 7, 8 reduce the output of the secondary circuit side of the current transformer CT or the transformer PT to the input signal level of the digital protection device.

Further, the failure detection device 6F has the same configuration as the main protection device 6, and the failure detection input converter 7
F and 8F are provided, and the failure detection operation unit 9F performs failure detection with the failure detection element for each protection element.

In FIG. 5, the main circuit current of the generator motor 1 detected by the current transformer CT8 is converted from the secondary circuit of the current transformer CT8 to the main protection input for the overcurrent relay element of the main protection device 6. Input to the device 7. This secondary current is input to the fault detection input converter 7F for the overcurrent relay element of the fault detection device 6 in a series connection (series). Next, the secondary current returns to the main protection device 6 and is input to the main protection input converter 8 for the generator ratio differential relay element. It is input to the detection input converter 8F.

As described above, in the conventional digital protection device, the input converters 7, 7F, 8, 8F are provided separately for each protection element, and separately for the main protection device 6 and the failure detection device 6F.
The system had a complicated configuration.

FIG. 6 is a configuration diagram showing an example of the configuration of an input converter in a conventional digital protection device in which protection elements are duplicated instead of failure detection elements. The main protection device 6 is provided in duplicate to prevent runaway of the main protection device 6A of one system, and to enable protection of the remaining system to be continued in the case of one system failure.

In FIG. 6, an A-system input converter 7A, 8A and an A-system protection operation unit 9 are provided inside an A-system protection device 6A.
A is provided. Similarly, the B-system input converters 7B and 8B and the B-system protection operation unit 9 are provided inside the B-system protection device 6B.
B is provided. The flow of the secondary circuit current of the current transformer CT8 in this case is the same as that in FIG.

[0017]

As described above, in the conventional digital protection device shown in FIG. 4, in principle, an instrumentation transformer PT or an instrumentation current transformer CT is provided for each protection element. Since the instrumentation transformer PT or the instrumentation current transformer CT is provided for every three protection elements, the number of the instrumentation transformers PT and the instrumentation current transformers CT increases, and the closure for accommodating the instrumentation transformer PT or the instrumentation current transformer CT is increased. The size of the switchboard also increases.

[0018] Therefore, the equipment cost is increased, and it is necessary to secure a wide space for installing the closed switchboard. In particular, underground power plants such as pumped storage power plants have the disadvantage of affecting the amount of civil engineering excavation and increasing civil engineering costs.

In the configuration of the input converter in the conventional digital protection device shown in FIGS. 5 and 6, each of the protection elements, the main protection device 6 and the failure detection and protection device 6F are separately or duplicated. Since the input converters 7 and 8 are separately provided for the system main protection device 6A and the system B main protection device 6B, not only the economy as the main protection devices 6 and 6F is impaired, but also the size of the protection device is large. Become. Further, since the secondary circuit current of the current transformer CT is routed between the input converters 7 and 8 in a complicated manner, the reliability of the device is not favorable.

Therefore, the present invention reduces the number of instrumentation transformers PT and instrumentation current transformers CT to the minimum necessary, and also reduces the number of input converters of the digital protection device rationally, thereby achieving economical efficiency. It is an object of the present invention to provide an efficient, compact and reliable digital protection device.

[0021]

According to a first aspect of the present invention, there is provided a digital protection apparatus for detecting a circuit voltage of a main circuit of a main transformer or a main circuit on an output side of a generator, and a main transformer. Current transformer for detecting the circuit current on the main circuit side and the midpoint point side of the main circuit or generator, and the secondary circuit voltage of the instrument transformer and the secondary circuit current of the instrument current transformer And a plurality of protection elements that operate according to the type of accident when an electrical accident occurs in the generator based on a signal from the input converter. In the protection device, when the detection points of the circuit voltage or the circuit current required by the plurality of protection elements are the same, the instrument transformer or the current transformer for the instrument is shared. .

In the digital protection device according to the first aspect of the present invention, the main circuit voltage at the same detection point of the main transformer or the generator is detected by a common single instrument transformer PT, and the same is applied to the transformer or the transformer. The main circuit current at the same detection point of the generator is detected by one common current transformer CT. Then, the voltage converter or the current signal is amplified by a necessary protection element on the input converter side of the protection element. Thereby, the number of the transformers for an instrument PT and the current transformers for an instrument CT can be reduced.

A digital protection device according to a second aspect of the present invention is the digital protection device according to the first aspect, wherein the input converter is shared by a plurality of protection elements.

In the digital protection device according to the second aspect of the present invention, in addition to the operation of the digital protection device of the first aspect,
The input converter amplifies the voltage signal or the current signal at the same detection point by a necessary protection element. As a result, the number of input converters can be significantly reduced.

According to a third aspect of the present invention, there is provided a digital protection device comprising: a main transformer of a main transformer or an instrumentation transformer for detecting a circuit voltage of an output side main circuit of a generator; and a main circuit of the main transformer or a generator. A current transformer for detecting the circuit currents on the main circuit side and the midpoint point side, a secondary circuit voltage of the instrument transformer and a secondary circuit current of the current transformer for inputting a predetermined signal level An input converter, a plurality of protection elements that operate according to the type of accident when an electrical accident occurs in the generator based on a signal from the input converter, and a protection element when the protection element fails. If the detection points of the circuit voltage or circuit current required by the plurality of protection elements are the same in a digital protection device having a failure detection element for preventing runaway of While sharing the container, Characterized by a shared force transducer relative to the protective element and the fault detection element.

In the digital protection device according to the third aspect of the present invention, a common input converter is provided for both the protection element and the fault detection element, and the secondary circuit of the instrument transformer or the instrument current transformer is provided. The signal is input to a common input converter and distributed to each element. Thus, the number of input converters can be reduced to half.

A digital protection device according to a fourth aspect of the present invention is the digital protection device according to the third aspect, wherein the same protection for preventing runaway of the protection element in the event of a failure of the protection element instead of the failure detection element. An additional element is provided, and the input converter is shared by one protection element and the other protection element.

In the digital protection device according to the fourth aspect of the present invention, the main protection device is provided in duplicate to prevent runaway of the protection element of one main protection device, and to protect the protection elements of both main protection devices. A common input converter is provided, and the secondary circuit signal of the instrument transformer or the current transformer is input to the common input converter and distributed to each protection element. Thus, the number of input converters can be reduced to half.

A digital protection device according to a fifth aspect of the present invention is the digital protection device according to the third aspect, wherein the input converter is shared by a plurality of protection elements and fault detection elements.

In the digital protection device according to the fifth aspect of the invention, in addition to the operation of the digital protection device of the third aspect,
The input converter amplifies the voltage signal or the current signal at the same detection point by a necessary protection element and a failure detection element. As a result, the number of input converters can be significantly reduced.

[0031]

Embodiments of the present invention will be described below. FIG. 1 shows a first embodiment of the present invention according to the embodiment of the present invention.
FIG. 4 is a single-line connection diagram when the digital protection device according to the embodiment is applied to protection of a generator motor and a main transformer. FIG. 1 shows a generator motor for a pumped storage power plant and a digital protection device for a main transformer, as in the conventional example shown in FIG.

In FIG. 1, the protection elements of the generator motor 1 include a ground fault overcurrent relay element 51G, a ground fault differential relay element 87G, a generator ratio differential relay element 87, an undervoltage relay element 27, a field loss relay. Element 40, overcurrent relay element 51, overcurrent relay element (for electric brake) 51
B, power relay element (for pumping input monitoring) 91L, power relay element (for input monitoring during phase adjustment operation) 91C, undervoltage relay element 27, overvoltage relay element 59, ground fault overvoltage relay element 64B, frequency relay element (overvoltage (For frequency monitoring) 9
5H and frequency relay element (for under-frequency monitoring) 95
L is provided.

The protection elements for the main transformer 4 include:
A negative phase relay element 46, an overcurrent relay element 51T, a ground fault overcurrent relay element 51TG, a cable ratio differential relay element 87C, and a main transformer ratio differential relay element 87T are provided.

Referring to FIG. 1, a protection system for the generator motor 1 will be described first. The current transformer CT1 detects the neutral point current of the generator motor 1 and acts on the ground fault overcurrent relay element 51G. The current transformers CT2 and CT6 detect the zero-phase current of the generator motor main circuit and act on the ground fault differential relay element 87G.

Instrument current transformer CT3 and instrument current transformer CT5
The main circuit current of the generator motor 1 is detected and the generator ratio differential relay element 87 and the field loss relay element 4 are detected.
0, overcurrent relay element 51, overcurrent relay element (for electric brake) 51B, power relay element (for monitoring pumping input)
91L and power relay element (for input monitoring during phase adjustment operation)
Acts in common on 91C. For this reason, the number of the current transformers for instrument CT can be reduced to the minimum number.

Voltage detection of the main circuit of the generator motor 1 is performed only by the instrument transformer PT1, and the undervoltage relay element 27, the overvoltage relay element 59, the ground fault overvoltage relay element 64B, the frequency relay element (for overfrequency monitoring) 95H. The frequency relay element (for monitoring under-frequency) 95L, the loss-of-field relay element 40, the power relay element (for monitoring pumping input) 91L, and the power relay element (for monitoring input during phase adjustment operation) 91C operate in common. Therefore, the number of instrument transformers PT can be reduced to the minimum number.

Next, a protection system for the main transformer 4 will be described. Current transformer CT4 and current transformer CT8
Detects the current of the main transformer 4 and acts in common with the main transformer ratio differential relay element 87T, the negative phase relay element 46, the overcurrent relay element 51T, and the cable ratio differential relay element 87C. I do. For this reason, the number of the current transformers for instrument CT can be reduced to the minimum number. Then, the current transformer for instrument CT7 detects the neutral point current of the main transformer 4 and acts on the ground fault overcurrent relay element 51TG. Current transformer for instrument CT
9 acts on the cable ratio differential relay element 87C in combination with the current transformer CT8.

As described above, the detection of the voltage and the current is performed by the minimum number of the transformers for the instrument PT and the current transformer for the instrument CT, and the detected signal is supplied to each protection element in common. And the number of current transformers CT for the instrument can be reduced.

FIG. 2 is a configuration diagram showing an example of an input converter configuration of a protection element and a failure detection element in the digital protection device according to the first embodiment of the present invention. The input converter 11 is different from the conventional example shown in FIG.
Is provided outside. As in the conventional example shown in FIG. 5, an overcurrent relay element 51 and a power generation element are used as a protection element in the main protection operation section 12 of the main protection apparatus 10 and a failure detection element in the failure detection operation section 12F of the failure detection apparatus 10F. This shows a combination of the machine ratio operation relay element 87.

In FIG. 2, the main circuit current of the generator motor 1 detected by the current transformer CT5 is input to only one input converter 11 common to the protection system for the generator motor 1. The input converter 11 outputs the same main circuit current signal to the main protection device 10 and the failure detection device 10F. Protection elements 51 and 87 in the main protection calculation unit 12 in the main protection device 10.
And a failure detection element in the failure detection operation unit 12F in the failure detection device 10F, the generator motor 1
For the main circuit current signal, the relay operation of the overcurrent relay element 51 and the relay operation of the generator ratio differential relay element 87 are performed to determine the failure.

As described above, it is sufficient to provide one set of the input converters 11 in common, so that the cost of the digital protection device can be reduced and the size of the device can be reduced, and further, the electric wire can be connected to the secondary circuit of the current transformer CT. There is no need to route it, and the reliability can be improved.

Next, FIG. 3 is a configuration diagram showing an example of the input converter configuration of the duplicated protection element in the digital protection device according to the first embodiment of the present invention. 2, the same protection element (main protection calculation unit 12F) for preventing runaway of the protection element in the event of a protection element failure is additionally provided in place of the failure detection element. The converter 11 is commonly used for one protection element (main protection operation unit 12F) and the other protection element (main protection operation unit 12F).

In FIG. 3, the main circuit current of the generator motor 1 detected by the current transformer CT5 is input to only one input converter 11 common to the protection system for the generator motor 1. Input converter 11 outputs the same main circuit current signal to A-system protection device 10A and B-system protection device 10B. The A-system protection calculation unit 12A in the A-system protection device and the B-system protection calculation unit 12B in the B-system protection device respond to the common input of the main circuit current signal of the generator motor 1 by the relay of the overcurrent relay element 51. Calculation and relay calculation of the generator ratio differential relay element 87 are performed to determine a failure.

As described above, it is sufficient to provide one set of the input converters 11 in common, so that the cost of the digital protection device can be reduced and the size of the device can be reduced. There is no need to route it, and the reliability can be improved.

[0045]

As described above, according to the present invention, the number of instrument transformers and instrument current transformers required to protect the generator motor and the main transformer can be reduced. The closed switchboard that houses the instrument and the current transformer for the instrument can also be made compact, and the equipment cost can be reduced.

Further, since the installation space of the closed switchboard can be reduced, the amount of civil engineering excavation at the underground power plant can be reduced, and the civil engineering cost can be reduced. Also, only one set of input converters of the digital protection device needs to be provided in common, and the number of input converters can be reduced to reduce the size and cost of the digital protection device. Further, it is not necessary to route an electric wire to the secondary circuit of the current transformer CT, and the reliability is improved.

[Brief description of the drawings]

FIG. 1 is a single-line connection diagram when a digital protection device according to a first embodiment of the present invention is applied to protection of a generator motor and a main transformer.

FIG. 2 is a configuration diagram showing an example of an input converter configuration of a protection element and a failure detection element in the digital protection device according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing an example of an input converter configuration of a duplicate protection element in the digital protection device according to the first embodiment of the present invention.

FIG. 4 is a single-line connection diagram when a conventional digital protection device is applied to protection of a generator motor and a main transformer.

FIG. 5 is a configuration diagram showing an example of an input converter configuration in a conventional digital protection device including a protection element and a failure detection element.

FIG. 6 is a configuration diagram showing an example of an input converter configuration in a conventional digital protection device in which protection elements are duplicated.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Generator motor 2 Parallel circuit breaker 3 Phase sequence switching disconnector 4 Main transformer 5 Cable 6 Main protection device 6A A system protection device 6B B system protection device 6F Failure detection device 7 Main protection input converter 7A A system input conversion 7B B-system input converter 7F Failure detection input converter 8 Main protection input converter 8A A-system input converter 8B B-system input converter 8F Failure detection input converter 9 Main protection operation unit 9A A-system protection operation unit 9B B System protection operation unit 9F Failure detection operation unit 10 Main protection device 10A A system protection device 10B B system protection device 10F Failure detection device 11 Input converter 12 Main protection operation unit 12A A system protection operation unit 12B B system protection operation unit 12F Failure Detection calculation section PT1 to PT3 Instrument transformer CT1 to CT13 Instrument current transformer 27 Undervoltage relay element 40 Loss of field relay element 46 Negative phase relay element 51 Overcurrent relay element 51B Overcurrent relay element (for electric brake) 51G Ground fault overcurrent relay element 51T Overcurrent relay element 51TG Ground fault overcurrent relay element 59 Overvoltage relay element 64B Ground fault overvoltage relay element 87 Generator ratio operation relay element 87G Ground fault operation relay element 87C Cable ratio operation relay element 87T Main transformer ratio operation relay element 91L Power relay element (for monitoring pumping input) 91C Power relay element (for monitoring input during phase adjustment operation) 95H Frequency relay element (for overfrequency monitoring) 95L frequency relay element (for under-frequency monitoring)

Claims (5)

[Claims] 1. An instrument transformer for detecting a circuit voltage of a main circuit of a main transformer or an output side main circuit of a generator, a main circuit of the main transformer or a main circuit side of the generator and a midpoint point. Current transformer for detecting the side circuit current, and an input converter for inputting the secondary circuit voltage of the instrument transformer and the secondary circuit current of the current transformer for conversion into a predetermined signal level And a plurality of protection elements that operate according to the type of accident when an electrical accident occurs in the generator based on a signal from the input converter. A digital protection device, wherein when the detection points of the required circuit voltage or circuit current are the same, the instrument transformer or the instrument current transformer is shared. 2. The digital protection device according to claim 1, wherein said input converter is shared by a plurality of said protection elements. 3. An instrument transformer for detecting a circuit voltage of a main circuit of a main transformer or an output main circuit of a generator, a main circuit of the main transformer or a main circuit side of the generator and a midpoint point. Current transformer for detecting the side circuit current, and an input converter for inputting the secondary circuit voltage of the instrument transformer and the secondary circuit current of the current transformer for conversion into a predetermined signal level A plurality of protection elements that operate according to the type of accident when an electrical accident occurs in the generator based on a signal from the input converter, and a runaway of the protection element when the protection element fails. In the digital protection device provided with a failure detection element for preventing a failure, when the detection points of the circuit voltage or the circuit current required by the plurality of protection elements are the same, the transformer for the instrument or the transformer for the instrument is used. While sharing the sink, A digital protection device, wherein the input converter is shared by the protection element and the failure detection element. 4. The digital protection device according to claim 3, further comprising an identical protection element for preventing runaway of the protection element when the protection element fails, in place of the failure detection element, A digital protection device wherein the input converter is shared by one protection element and the other protection element. 5. The digital protection device according to claim 3, wherein said input converter is shared by a plurality of said protection elements and said fault detection elements.