JPH0334285B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a protective relay circuit that monitors a signal transmission circuit that sends a status signal of a device or circuit to a protective relay for protecting the device or circuit, and detects an abnormality. Regarding monitoring equipment.

[Prior art and its problems]

When an abnormality occurs in important electrical machines or circuits, it is necessary to reliably detect this abnormality and promptly take measures such as disconnecting these machines or circuits from the power supply. For example, if a large-capacity generator or large-capacity transformer connected to the power system experiences an overcurrent for some reason, and the overcurrent is not detected and burns out, the damage to this equipment can be repaired. Until this happens, the power system will suffer significant damage.

In order to prevent the above-mentioned accidents, important electrical equipment is often equipped with redundant protection devices. For example, when protecting a generator from overcurrent, an overcurrent continuator is connected to the secondary side of a current transformer inserted in the generator main circuit, and the generator current continues at a predetermined value or higher for a predetermined period of time. When current flows, this overcurrent relay operates, tripping the circuit breaker and disconnecting the generator from the grid.In addition, there is a A second current transformer is inserted therein, and a second overcurrent relay is connected to the secondary side of the second current transformer to improve the reliability of protection against overcurrent abnormalities. Such a method is also applied to elements to be protected other than overcurrent, such as voltage and rotational speed.

By the way, these protective relays such as overcurrent relays do not operate all the time, but are required to operate reliably in abnormal situations, and for this purpose, periodic operation checks are required. Taking an overcurrent relay as an example, this operation check first shorts the secondary side of the current transformer inserted in the main circuit, then disconnects the overcurrent relay from the secondary side of the current transformer and installs it separately. A current corresponding to the predetermined overcurrent of the generator is applied from a simulated current source to this overcurrent relay to confirm that it operates. Once this operation check is completed, reverse the above procedure, i.e., disconnect the simulated current source from the overcurrent relay, connect it to the secondary side of the current transformer, and then release the short circuit on the secondary side of the current transformer and restore it. It returns it to the state of .

For example, if the short circuit on the secondary side of the current transformer is not released when restoring to the original state after the above-mentioned operation check, when the generator enters an overcurrent state,
Since this overcurrent information is not transmitted to the overcurrent relay, the generator will burn out. In other words, even if the protective relay is constantly inspected to ensure that it operates properly in the event of an abnormality, if there is a short circuit or disconnection in the circuit leading to the protective relay, information about the abnormality in the protected equipment such as the generator will be transmitted to the protective relay. Failure to do so may result in a serious accident. Moreover, there is a problem in that it is difficult to detect a failure in the circuit that transmits information to the above-mentioned protective relay.

[Purpose of the invention]

The present invention provides a protective relay circuit monitoring device that constantly monitors a signal transmission circuit that transmits a status signal sent by a detector that detects the status of protected equipment such as electrical equipment to a protective relay, and reliably detects abnormalities in the circuit status. The purpose is to provide.

[Key points of the invention]

The present invention further extends the signal transmission circuit that transmits the status signal transmitted by the first detector that detects the status of the protected equipment to the protective relay, extracts the signal, and transmits the status signal and the second detector. The purpose of this system is to monitor the state of the signal transmission circuit and detect abnormalities in this circuit by comparing the state signal with the current state signal.

[Embodiments of the invention]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, which is a protective relay circuit monitoring device using current elements of a three-phase alternating current generator, in which redundancy is provided by two sets of protective relays. . Note that the configuration of each phase is the same, so to avoid complicating the diagram, T
Only the phases are described, and the R phase and S phase are omitted.

In FIG. 1, the T-phase current of the three-phase alternator 1 is detected separately by independent current transformers 11 and 31, respectively. 10 is a first current protection circuit, in which the current detected by the current transformer 11 passes through the normally closed current transformer circuit contact 15 to the main current coil 12A of the current relay 12 and the main current coil 28 of the power relay 28.
A further flows through the current comparator 3 in series, but if there is a relay that requires current detection other than the above, it may be connected in series to the above-mentioned continuator or the like. When checking the current operation of the current relay 12 and the power relay 28, first check the short-circuit contact 1, which is always open.
4 is closed and the secondary side of the current transformer 11 is short-circuited, the current transformer circuit contact 15 is opened, and the simulated current circuit contact 16, which is always open, is closed to generate a simulated current from the simulated current source 13. A current signal is passed in series to the inspection current coil 12B of the current relay 12 and the inspection current coil 28B of the power relay 28. Since the signal level of this simulated current signal can be freely changed by adjusting the simulated current source 13, these current relays 1
You can check operations such as 2.

Once the operation check is completed, the procedure is the reverse of the above, i.e., first open the simulated current circuit contact 16, then close the current transformer circuit contact 15, and then close the short circuit contact 1.
If 4 is opened, the original state is restored.

After checking the operation of the first current protection circuit 10, the current transformer 31, current relay 32 and its main current coil 3 are
2A and inspection current coil 32B, power relay 48 and its main current coil 48A and inspection current coil 48B, simulated current source 33, normally open short circuit contact 34, normally closed current transformer circuit contact 35, and The operation of the second current protection circuit 30, which is the simulated current circuit contact 36 which is always open, is checked, and the procedure is the same as that for the first current protection circuit 10.

Since the same current flows through the primary sides of current transformers 11 and 31, if the current transformation ratios of both current transformers are the same, current transformer 1 to which these protective relays are connected
As long as there is no abnormality in the secondary side circuits 1 and 31, the currents from both current transformers flowing into the current comparator 3 are the same. If short-circuit contact 14 or 34 or current transformer circuit contact 15 or 35 has malfunction or poor contact, or if the secondary circuit of current transformer 11 or 31 has an abnormality such as disconnection, short circuit, or grounding, A difference is generated between the two current values flowing into the current comparator 3. The current comparator 3 converts two currents into DC voltages proportional to their current values and compares them, or uses the magnetic action of the currents to cause both currents to act in opposite polarities to each other, so that the currents become unbalanced. By incorporating a means for detecting the magnetic flux generated when the circuit becomes weak, it is possible to know whether there is a circuit abnormality and the extent of the abnormality. Note that when the current transformation ratios of the current transformers 11 and 31 are different, the operation of the current comparator 3 may be set in consideration of the current difference.

28C and 28D in FIG. 1 are the main voltage coil and inspection voltage coil, respectively, of the power relay 28, and 48C and 48D are the main voltage coil and inspection voltage coil, respectively, of the power relay 48, the operation of which will be described later. Therefore, I will not discuss it here.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention, in which the current elements of a three-phase alternating current generator are protected by a set of protective relays, and as in the case of FIG. Only the phases are listed.

In FIG. 2, the current transformer 11 that detects the T-phase current of the three-phase alternating current generator 1 transmits the secondary current to the main current coil 17A of the current relay 17 and the current comparator 3 through the current transformer circuit contact 19. flows in series. This current relay 17 does not have a current coil for inspection, so when inspecting the operation, short-circuit the secondary side of the current transformer 11 with the short-circuit contact 14, and then connect the current transformer circuit contact 1
9 and the simulated current circuit contact 16 to connect the main current coil 1.
The operation is checked by switching the current flowing to 7A from the secondary side of the current transformer 11 to the simulated current source 13. It has already been explained that an abnormality in the protective relay circuit can be detected by adding the converter 31 to the T phase, connecting its secondary side to the current comparator 3, and comparing the secondary currents of both current transformers 11 and 31. As I said.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention, in which a three-phase alternating current generator is protected by two sets of voltage element protective relays, but the diagram is complicated. In order to avoid this, only the area between the R phase and T phase lines is shown.

In FIG. 3, 20 is a first voltage protection circuit, and the line voltage of the R phase and T phase of the three-phase alternating current generator 1 detected by the instrument transformer 21 is connected to the normally closed instrument transformer. Voltage relay 2 via circuit contact 25
2 main voltage coil 22C, main voltage coil 28C of power relay 28, and voltage comparator 5. However, if there are other relays that require voltage detection in addition to the above, connect them in parallel to the above relays, etc. good.
When checking the voltage operation of this voltage relay 22 and power relay 28, check the voltage transformer circuit contact 2.
5 is opened and the normally closed simulated voltage circuit contact 26 is closed to input the simulated voltage signal from the simulated voltage source 23 to the inspection voltage coils 22D and 28D of the voltage relay 28, thereby generating the simulated voltage source 23. Change the voltage. When the operation check is completed, the potential transformer circuit contacts 25 and the simulated voltage circuit contacts 26 are returned to their original states.

The second voltage protection circuit 40 includes an instrument transformer 41 that detects the line voltage of the R phase and T phase, a voltage relay 42 and its main voltage coil 42C, an inspection voltage coil 42D, and a power relay 48 and its main voltage coil 4.
8C, an inspection voltage coil 48D, a voltage transformer circuit contact 45, and a simulated voltage circuit contact 46, and the simulated voltage source 23 is connected to the first voltage protection circuit 2.
It is shared with 0. The operation of this second voltage protection circuit 40 is the same as that of the first voltage protection circuit 20 described above, so the explanation thereof will be omitted. Also, the main current coils 28A and 48A and the inspection current coils 28B and 48B of the power relays 28 and 48, respectively.
has already been explained and is not relevant to voltage protection, so it will not be discussed here.

If there is an abnormality in the secondary circuits of the two voltage transformers 21 and 41, such as disconnection, short circuit, grounding, or malfunction or contact failure of the voltage transformer circuit contacts 25 or 45, this is input to the voltage comparator 5. Since there is a difference between the two voltages, the voltage comparator 5 can easily detect the presence or absence of the above-mentioned circuit abnormality and the extent of the abnormality.

FIG. 4 is a circuit diagram showing a fourth embodiment of the present invention, in which a three-phase alternating current generator is protected by a protective relay of one set of voltage elements, and the line between R and S phases is Only voltage protection is listed.

In FIG. 4, each line voltage of the three-phase alternating current generator 1 is detected by V-connecting two potential transformers 21 and 41. The voltage between R and S is transmitted from the secondary side of the V-connected instrument transformer to the voltage relay 27 via the normally closed instrument transformer circuit contact 25.
While the main voltage coil 27C and the voltage comparator 5 are applied, the voltage between ST and T on the secondary side of the potential transformer is input to the voltage comparator 5, and this voltage between R and S and ST Monitors for circuit abnormalities in the secondary circuit of the voltage transformer by comparing the voltage between the two. If the line voltages of the three-phase circuit are balanced, it is possible to monitor circuit abnormalities with the circuit configuration of this embodiment without particularly adding a voltage transformer. 23 is a simulated voltage source, 26 is a simulated voltage circuit contact, and when inspecting the operation, the power applied to the main voltage coil 27C of the voltage relay 27 is switched from the secondary side of the voltage transformer to this simulated voltage source 23. and use it.

The voltage comparator 5 described in the third and fourth embodiments only receives a voltage input, and its structure, function, etc. are almost the same as the current comparator 3 described above.

〔Effect of the invention〕

According to this invention, the signal transmission circuit that transmits the status signal from the detector that detects the status of the protected equipment to the protective relay is extended, the status signal is extracted, inputted to the signal comparator, and the signal is transmitted from the second detector to the protective relay. The state signal is also input to the signal comparator and compared. With such a configuration, an abnormality in the signal transmission circuit can be detected from the difference between the two status signals, so that it is possible to prevent the protection relay from operating due to the circuit abnormality, thereby preventing a serious failure from occurring in the protected equipment. Furthermore, it is also possible to detect an abnormality in the signal emitted by the detector due to a failure of the detector itself.

Note that if the protected device is an important device and multiple protective relays are installed, the reliability of protection can be improved by adding only a signal comparator.

[Brief explanation of drawings]

1, 2, 3, and 4 are circuit diagrams showing first, second, third, and fourth embodiments of the present invention. 1... Three-phase alternator, 3... Current comparator, 5
... Voltage comparator, 10 ... First current protection circuit, 1
1, 31...Current transformer, 12, 17, 32...Current relay, 12A, 17A, 32A...Current relay main current coil, 12B, 32B...Current coil for current relay inspection, 13, 33...Simulation voltage source, 1
4, 34... Short circuit contact, 15, 19, 35... Current transformer circuit contact, 16, 36... Simulated current circuit contact, 20... First voltage protection circuit, 21, 41...
Instrument transformer, 22, 27, 42... Voltage relay, 22C, 27C, 42C... Voltage relay main voltage coil, 22D, 42D... Voltage relay inspection voltage coil, 23... Simulated voltage source, 25, 45 …
...Instrument transformer circuit contact, 26,46...Simulated voltage circuit contact, 28,48...Power relay, 28
A, 48A...Power relay main current coil, 28
B, 48B...Current coil for power relay inspection, 2
8C, 48C...Power relay main voltage coil, 28
D, 48D... Voltage coil for power relay inspection, 3
0...Second current protection circuit, 40...Second voltage protection circuit.

Claims (1)

[Claims] 1 The status signal emitted by the first detector that detects the status of the protected equipment is guided to the protective relay by the signal transmission circuit, while the simulated status signal from a simulated signal source that is installed separately is used to check the operation of the protective relay. A second detector for detecting a state of a protected device; and a second detector for detecting a state of a protected device; 1. A protective relay circuit monitoring device comprising means for comparing a status signal emitted by the first detector with a status signal from the first detector taken out from the load side of the signal transmission circuit open section.