JP2012200049A - Power-generation plant and method of protecting the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power-generation plant capable of avoiding damage to a steam turbine and stably supplying electric power even if a normal protection operation of releasing a first circuit breaker is not performed, and a method of protecting the same.SOLUTION: When a first predetermined period of time has elapsed after a reverse power relay 12 is operated, a protection circuit 1 releases a first circuit breaker 6. When the first circuit breaker 6 continues IN state for a second predetermined period of time or more while a steam turbine 13 is in a trip state, the protection circuit 1 releases a second circuit breaker 3. Thereby, it is possible to reliably prevent damage to the steam turbine 13 even when the first circuit breaker is not released by a breakdown, for example.

Description

  The present invention relates to a power plant and a protection method thereof.

  In a power plant having a steam turbine, during normal power generation operation, steam generated by a boiler or the like is supplied to and driven by the steam turbine, and the generator is driven by the generated torque to generate electric power, which is supplied to the grid. .

  However, when steam is not supplied to the steam turbine with the generator connected to the grid, typically when the steam turbine is in a tripped state, that is, when the steam turbine stops, the steam turbine does not generate torque. In such a case, instead of the generator being driven by the steam turbine, the power from the grid is received in reverse, so-called reverse power is applied to act as a motor to drive the steam turbine.

  Such an operation state is called motoring operation, and the rotation speeds of the steam turbine and the generator are maintained at the rated rotation speed (generally 50 Hz or 60 Hz) in synchronization with the grid.

  By the way, the steam supplied to a steam turbine has the effect | action which passes the inside of a steam turbine and cools the internal structure other than the effect | action which drives a steam turbine. At the time of motoring operation, the high speed state in which the rotational speed is synchronized with the rated rotational speed is maintained in a state where the steam having the cooling action is lost. For this reason, the temperature of the steam turbine exhaust chamber or the like may increase due to windage and the steam turbine may overheat.

  Therefore, in order to protect the steam turbine, the reverse power relay detects that the motoring operation has been performed, opens the first circuit breaker, and disconnects the generator from the grid.

  When there is no reverse power supplied from the grid, the generator no longer drives the steam turbine as a motor. For this reason, the rotational speeds of the steam turbine and the generator are reduced, and the rotational speed becomes extremely low with no influence of windage loss with the passage of time.

  In general, the temperature of the turbine exhaust chamber or the like does not rise rapidly. Therefore, if the steam turbine is in a short time (hereinafter, this short time is, for example, 60 seconds), the motoring operation can be permitted. Therefore, after the start of the motoring operation is detected by the reverse power relay, the delay time is used to reduce the time that the steam turbine allows for the motoring operation with a margin (hereinafter, this time is assumed to be, for example, 20 seconds). In general, the first circuit breaker is opened after the elapse of time. This is performed in order to eliminate the influence of the transient short-time driving situation and to stabilize the driving.

  FIG. 3 shows a configuration of a power plant including a protection device 101 according to a conventional technique.

  Electric power from the generator 14 is transmitted to the grid 2 via the transmission path 5. The power transmission path 5 is provided with a first circuit breaker 6, a main transformer 4, and a second circuit breaker 3 provided in a switch station in the plant, and from a generator 14 in this order during normal power generation operation. Electric power is transmitted to the grid 2. During the motoring operation described above, the power of the grid 2 is transmitted to the generator 14 in the reverse order.

  By the way, valves such as pumps and fans are installed as a large number of auxiliary machines (not shown) in the power plant, and an in-house power source 7 is used as a power source for driving the electric motor 8 of these auxiliary machines.

  As the in-house power supply 7, one that is branched from the power transmission path 5 between the first circuit breaker 6 and the second circuit breaker 3 and whose voltage is stepped down by the in-house transformer 9 is used. Therefore, during normal power generation operation, the power generated by the generator as the in-house power source 7 is branched from the power transmission path 5 and supplied. On the other hand, during motoring operation, electric power is supplied from the grid 2 via the second circuit breaker 3 and the in-house transformer 9 to become the in-house power source 7.

  When the in-house power supply 7 is lost, the auxiliary motor 8 stops, and the steam turbine stops, that is, trips. However, some important auxiliary motors 8 need to continue to operate even when the steam turbine is tripped.

  Therefore, power for these important auxiliary motors 8 is supplied by the emergency diesel generator 10. The emergency diesel generator 10 detects the loss of the in-house power supply 7 and starts to start. However, since the emergency diesel generator 10 requires time until the diesel engine is started, it takes 30 seconds to 50 seconds (hereinafter, this time is 35 seconds) before power can be supplied. For this reason, the important auxiliary motor 8 is temporarily stopped for 35 seconds and then supplied with power and restarted.

  FIG. 4 shows an internal circuit of the protection device 101. The reverse power relay operation 18 by the motoring operation is detected by the reverse power relay 15 and a detection signal 19 is output. In the delay circuit 20, the detection signal 19 is delayed for a predetermined time (here, 20 seconds), and the delayed signal 21 is a first circuit breaker opening command signal 23 indicating a first circuit breaker opening command 22. 6 is output. Thereby, the 1st circuit breaker 6 is open | released.

JP-A-63-7142

  However, when a lightning strike or the like occurs in the power transmission path 5, a wide range of damage occurs in the electrical equipment. First, an overcurrent is generated in the generator 14, the main transformer 4, and the in-house transformer 9, and the generator 14 is stopped, and the steam turbine 13 is stopped by the interlocking interlock thereof, that is, trips to the steam turbine 13. Is shut off and motoring operation is started.

  In such a case, the reverse power relay 15 is activated to open the first circuit breaker 6 as a normal protection operation. However, if an accident occurs that includes the first circuit breaker 6 and the reverse power relay 15 in the damage range of the electrical equipment, the first circuit breaker 6 remains in the “ON” state and is not opened, so the motoring operation is eliminated. The temperature of the turbine exhaust chamber rises. As a result, the steam turbine may be overheated.

  In view of the above circumstances, the present invention avoids the failure of important equipment such as damage to the steam turbine and stabilizes power even when the reverse power relay is activated and the normal protection operation for opening the first circuit breaker is not performed. It is an object of the present invention to provide a power plant that can be supplied as a power source and a protection method thereof.

  A power plant according to the present invention includes a steam turbine, a generator that is driven by the steam turbine to generate electric power, a power transmission path for transmitting the power generated by the power generator to a grid, and the power transmission path. A first circuit breaker for interrupting power transmission between the generator and the grid, and the generator provided between the first circuit breaker and the grid in the power transmission path. A second circuit breaker for interrupting power transmission between the power grid and the grid, a reverse power relay for detecting occurrence of motoring operation of the steam turbine, and a first after the reverse power relay is activated And a protection device having a first circuit breaker opening means for opening the first circuit breaker when a predetermined time elapses, wherein the protection device further includes the steam turbine in a trip state and the first circuit breaker. There wherein the state of "containing" is provided with a second circuit breaker opening means for opening said second circuit breaker to continue the second predetermined time or more.

  The power plant protection method of the present invention includes the steam turbine, the power generator, the power transmission path, the first circuit breaker, the second circuit breaker, the reverse power relay, and the protection device. A power plant protection method comprising: when the steam turbine is in a tripped state and the first circuit breaker is in the “on” state for a second predetermined time or longer by the protection device. It is characterized by opening.

  According to the power plant and the protection method of the present invention, the turbine exhaust chamber temperature increases due to the motoring operation when the reverse power relay is activated and the normal protection for opening the first circuit breaker is not performed. By opening the second circuit breaker before starting, it is possible to avoid failure of important equipment such as turbine damage and to supply power stably.

The layout which showed the structure of the power plant by Embodiment 1-5 of this invention. The circuit diagram which showed the structure of the protective device contained in the power plant by the Embodiments 1-5. The layout which showed the structure of the conventional power plant. The circuit diagram which showed the structure of the protective device contained in the conventional power plant.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1
(Constitution)
A power plant and a protection method thereof according to Embodiment 1 of the present invention will be described with reference to FIG.

  In this Embodiment 1, generation | occurrence | production of motoring driving | operation is detected using a different component from the reverse power relay used by original protection operation, and a 2nd circuit breaker is open | released. When the second circuit breaker is opened, the grid and the generator are disconnected, so that no power is supplied from the grid and the motoring operation is canceled.

  During normal power generation operation, the electric power output from the generator 14 passes through the first circuit breaker 6, the main transformer 4, and the power transmission path 5 provided with the second circuit breaker 3 provided in the on-site switchgear in this order. Power is transmitted to the grid 2. In the motoring operation, the power of the grid 2 is transmitted to the generator 14 in the reverse order.

  Further, an in-house power source 7 is installed as a power source for driving an auxiliary electric motor 8 such as a pump or a fan.

  During normal power generation operation, a voltage that is branched from the power transmission path 5 between the first circuit breaker 6 and the second circuit breaker 3 and stepped down by the in-house transformer 9 is used as the in-house power supply 7.

  At times other than normal power generation operation including motoring operation, electric power supplied from the grid 2 through the second circuit breaker 3 and the in-house transformer 9 is used as the in-house power source 7.

  When the in-house power supply 7 is lost, the auxiliary motor 8 stops and the steam turbine 13 stops, that is, trips.

  In the first embodiment, the emergency diesel generator 10 used for backup when the in-house power supply 7 is lost may not necessarily be provided.

  Here, as described above, when an accident occurs in the transmission line 5 and an overcurrent occurs in the electrical equipment, the generator 14 is stopped, the steam turbine 13 is stopped, the steam to the steam turbine 13 is shut off, and the motoring operation is performed. Is started. When the first circuit breaker 6 and the reverse power relay 15 are not broken, the first circuit breaker 6 is opened by the operation of the reverse power relay 15 and the motoring operation is canceled.

  However, if the first circuit breaker 6 or the reverse power relay 15 breaks down, the first circuit breaker 6 remains in the “on” state and is not released, and the motoring operation is not canceled. The turbine 13 may be damaged.

  Therefore, in the first embodiment, the trip of the steam turbine 13 and the “on” of the first circuit breaker 6 are separated from the configuration in which the reverse power relay 15 detects the motoring operation and opens the first circuit breaker 6. It is determined that the motoring operation is being performed when the operation continues even after a lapse of a certain time, and the second circuit breaker 3 is opened to automatically disconnect from the grid 2.

  FIG. 2 shows the configuration of the protection device 1 included in the power plant according to the first embodiment.

  As shown in FIG. 1, the protective device 1 has input terminals connected to the output terminals of the emergency oil pressure detection pressure switch 12, the first circuit breaker open / close limit switch 16, and the reverse power relay 15, respectively. The output terminals are connected to the input terminals of the second circuit breaker 3, the emergency diesel generator 10, and the first circuit breaker 6, respectively.

  The protection device 1 includes an AND circuit 30 and a delay timer 32 as components, and the NOT circuit 38 and the delay timer 20 do not necessarily have to be included.

  The AND circuit 30 includes a turbine trip signal 28 indicating the turbine trip 26 output from the emergency oil pressure detection pressure switch 12, and “ON” of the first circuit breaker 6 output from the first circuit breaker open / close limit switch 16. The first circuit breaker input signal 29 indicating the state 27 is input. When both are input, an output signal 31 is output from the AND circuit 30, and after being delayed by a delay timer 32 for a predetermined time, an output signal 33 is output. The output signal 33 indicates an opening command 34 for the second circuit breaker 3 and is given to the second circuit breaker 3 as a second circuit breaker opening command signal 35. Thereby, the 2nd circuit breaker 3 is open | released and the power transmission path 5 and the system grid 2 are interrupted | blocked.

(Function)
According to the first embodiment of the present embodiment having the above-described configuration, the turbine trip 26 is detected by the emergency oil pressure detection pressure switch 12 and the first circuit breaker open / close limit switch 16 detects the first circuit breaker. When it is detected that 6 is in the “ON” state 27, the output signal 31 from the AND circuit 30 starts to be measured for a predetermined time set by the delay timer 32. When the output signal 31 from the AND circuit 30 continues for a predetermined time set in the delay timer 32, the second breaker opening command signal 35 is given to the second breaker 3 by the output signal 33 from the delay timer 32. Released.

(effect)
Conventionally, only the configuration for detecting the motoring operation by the reverse power relay 15 and opening the first circuit breaker 6 is provided, and the power transmission path 5 is disconnected from the grid 2. On the other hand, according to the first embodiment, the motoring operation state is established when the turbine trip 26 and the “ON” state 27 of the first circuit breaker 6 continue for a predetermined time independently of this route. Therefore, the second circuit breaker 3 is opened, and the power transmission path 5 is automatically disconnected from the system grid 2. Thereby, even if it is a case where opening of the 1st circuit breaker 6 is not performed by some accident, damage to the steam turbine 13 can be prevented beforehand.

Embodiment 2
(Constitution)
A power plant and a protection method thereof according to Embodiment 2 of the present invention will be described with reference to FIGS. The second embodiment corresponds to a specific implementation of the set time of the delay timer 32 in the first embodiment.

  When the second circuit breaker is opened to eliminate the motoring operation, the in-house power supply 7 is lost, and even an important auxiliary machine that requires continuous operation is stopped. Therefore, in the second embodiment, when a motoring operation occurs, the original protection operation of opening the first circuit breaker 6 by operating the reverse power relay 15 as much as possible is left. Only when this protection does not operate normally due to a failure or the like, the second circuit breaker 3 is opened. Therefore, the state 27 in which the steam turbine 13 is in a trip state and the first circuit breaker 6 is “ON” does not stop even after the time that the first circuit breaker 6 should be opened after the reverse power relay 15 is activated. Only when continuing, the 2nd circuit breaker 3 shall be open | released.

  As described above, the turbine trip signal 28 from the emergency oil pressure detection pressure switch 12 and the first circuit breaker input signal 29 from the first circuit breaker open / close limit switch 16 are input to the AND circuit 30. When both are input, an output signal 31 is output from the AND circuit 30 and input to the delay timer 32.

  Here, the predetermined time set in the delay timer 32 to determine whether or not the output signal 31 from the AND circuit 30 has continued for a predetermined time is 30 seconds.

  When both the output signals 28 and 29 continue for the predetermined time, the output signal 33 from the delay timer 32 is established, and the second circuit breaker opening command signal 35 indicating the second circuit breaker opening command 34 is output and the second signal is output. The circuit breaker 3 is opened.

  The predetermined time set in the delay timer 32 is the first after the reverse power relay 15 is activated when the reverse power relay 15 outputs the output signal 19 indicating that the reverse power relay operation 18 is detected. The predetermined time until the circuit breaker 6 is opened, for example longer than 20 seconds, and the time for which the steam turbine 13 allows motoring operation, here needs to be shorter than 60 seconds, for example 30 seconds here. Is set.

  In other words, after the 20 seconds required for the path for opening the first circuit breaker 6 to operate without failure, the first circuit breaker 6 is not opened for some reason, and the motoring operation time is exceeded. By opening the second circuit breaker 3 in a short time, the power transmission path 5 is surely disconnected from the grid 2.

(Function)
With the above configuration, according to the second embodiment, the signal 28 indicating the turbine trip 26 and the signal 29 indicating the state 27 in which the first circuit breaker 6 is “ON” are input to the AND circuit 30 and output. When the state where the signal 31 is established continues for 30 seconds, an output signal 35 indicating the second circuit breaker opening command 34 is given from the delay circuit 32 to the second circuit breaker 3 to be opened.

(effect)
According to the second embodiment, even when the first circuit breaker 6 is still not opened at the time when the first circuit breaker 6 has been opened for a long time after the turbine is tripped, When the turbine trip 26 and the “ON” state 27 of the first circuit breaker 6 continue for 30 seconds, it is determined that the motoring operation state is continuing, the second circuit breaker 3 is opened, and the transmission line 5 By disconnecting from the grid 2, damage to the steam turbine 13 can be reliably prevented.

Embodiment 3
(Constitution)
A power plant and a protection method thereof according to Embodiment 3 of the present invention will be described with reference to FIGS.

  In the third embodiment, in addition to the configuration of the second embodiment, in FIG. 1, an important auxiliary motor that needs to be operated even when the steam turbine trips and the in-house power supply 7 is lost. As an emergency backup power source for 8, an emergency diesel generator 10 is provided.

  The emergency diesel generator 10 starts when it detects that the in-house power supply 7 has been lost, but it takes a predetermined time until the power can be supplied.

  In the present third embodiment, when the second circuit breaker 3 is opened to eliminate the motoring operation, when the steam turbine 13 is in a trip state and the first circuit breaker 6 is in the “on” state 27, The emergency diesel generator 10 is started immediately without delay so as not to hinder the continued operation of the important auxiliary equipment as much as possible.

  In the protection circuit 1 shown in FIG. 2, the output signal 28 indicating the turbine trip 26 and the output signal 29 indicating the state 27 in which the first circuit breaker 6 is “ON” are input to the AND circuit 30 and output signal 31. Is established, the output signal 37 indicating the emergency diesel generator start command 36 is immediately output to the emergency diesel generator 10 to start the start.

  As described above, the emergency diesel generator 10 takes 35 seconds from when a command is given until it can supply power.

(Function)
As described in the second embodiment, the turbine trip 26 detects the output signal 19 indicating the reverse power relay operation 18 from the reverse power relay 15 and the first circuit breaker 6 is not opened. When the state where the first circuit breaker 6 is turned on is continued for 30 seconds after being made, the second circuit breaker 3 is opened. In such a case, the power transmission path 5 is disconnected from the system grid 2, the in-house power supply 7 is lost, and no electric power is supplied to the auxiliary motor 8.

  Even in such a case, according to the second embodiment, the turbine trip 26 is detected, the state 27 in which the first circuit breaker 6 is “ON” is detected, and the output signal 31 of the AND circuit 30 is detected. When established, the output signal 37 indicating the emergency diesel generator start command 36 is immediately output to the emergency diesel generator 10 to start the start.

(effect)
According to the third embodiment, even if the reverse power relay 15 is activated as a normal protection operation and the first circuit breaker 6 is not opened, the emergency breaker is opened before the second circuit breaker 3 is opened. By starting the diesel generator 10 for a vehicle, it is possible to secure the in-house power source 7 that is the power source of the important auxiliary motor 8.

Embodiment 4
(Constitution)
A power plant and a protection method thereof according to Embodiment 4 of the present invention will be described with reference to FIGS. In the fourth embodiment, similarly to the first embodiment, the protection circuit 1 includes an AND circuit 30 and a delay timer 32, and further includes a delay timer 20. Further, as in the third embodiment, the emergency diesel generator 10 shown in FIG. 1 is provided.

  In the fourth embodiment, the second circuit breaker is opened after the time when the activated emergency diesel generator can supply power so as not to hinder the continued operation of important auxiliary equipment as much as possible. To be done.

  In FIG. 2, as described in the first embodiment, the output signal 28 indicating the turbine trip 26 and the output signal 29 indicating the “ON” state 27 of the first circuit breaker 6 are supplied to the AND circuit 30. When the output signal 31 is input and the output signal 31 continues for a predetermined time, the output signal 33 is output from the delay timer 32. This predetermined time is set to 45 seconds here, for example, based on the reasons described later.

  When the reverse power relay 15 detects the reverse power relay operation 18 due to the motoring operation, an output signal 19 indicating that is output to the delay timer 20. The signal is output as a signal 21 after being delayed for a predetermined time in the delay timer 20, for example, 20 seconds here. This signal 21 indicates a first circuit breaker opening command 22, and this first circuit breaker opening command signal 23 is given to the first circuit breaker 6 and opened.

  Further, as described in the third embodiment, the output signal 28 indicating the turbine trip 26 and the output signal 29 indicating the state 27 in which the first circuit breaker 6 is “ON” are input to the AND circuit 30 and output. When the signal 31 is established, the output signal 37 indicating the emergency diesel generator start command 36 is immediately output to the emergency diesel generator 10 to start the start. Here, it takes 35 seconds from when the emergency diesel generator 10 is given a command until it can supply power.

  Therefore, the time from when the turbine trip 26 is detected until the first circuit breaker 6 is opened (20 seconds), and the time until the emergency diesel generator 10 can supply power (35 seconds). Of these, the delay time of the delay timer 32 is set to 45 seconds as the longer time, that is, longer than 35 seconds and shorter than the time (60 seconds) during which the steam turbine 13 allows motoring operation. .

  When the input of the output signals 28 and 29 to the AND circuit 30 continues for 45 seconds, the output signal 33 is output from the delay timer 32 and the second circuit breaker opening command signal 35 is output to the second circuit breaker 3. Opened.

(Function)
According to the fourth embodiment having the above-described configuration, the emergency diesel generator 10 is instructed to start as soon as the turbine trip 26 is detected and the “ON” state 27 of the first circuit breaker 6 is detected. After 35 seconds, power can be supplied. Further, when 20 seconds have elapsed after the turbine trip 26 is detected, the first circuit breaker 6 is instructed to open.

  However, when the first circuit breaker 6 is not opened due to some failure and the “trip” state 27 of the turbine trip 26 and the first circuit breaker 6 continues for 45 seconds, the second circuit breaker opening command signal 35 is output. Then, the second circuit breaker 3 is opened.

(effect)
If the steam turbine 13 trips and the first circuit breaker 6 is in the “ON” state 27, a start command is immediately output to the emergency diesel generator 10, but 35 seconds before power can be supplied. Cost. The first circuit breaker 6 is commanded to open 20 seconds after the turbine trip 26 is detected, but nevertheless is not opened, and the turbine trip 26 and first circuit breaker 6 "entered" state 27 is When it continues for 45 seconds, the 2nd circuit breaker 3 is open | released. That is, the second circuit breaker 3 is opened 45 seconds after it has been ensured that the backup power source has been secured after 35 seconds have elapsed from the trip of the steam turbine 13 to the emergency diesel generator 10 rising. Thus, it is possible to reliably continue the important auxiliary machine.

Embodiment 5
(Constitution)
A power plant and a protection method thereof according to Embodiment 5 of the present invention will be described with reference to FIGS.

  In the fifth embodiment, the protection circuit 1 includes an AND circuit 30 and a delay timer 32 as in the third embodiment, and the emergency diesel generator 10 shown in FIG. The protection circuit 1 includes a NOT circuit 38.

  In the fifth embodiment, when the original protection is operated without any problem and the reverse power relay 15 is activated and the first circuit breaker 6 is opened, the emergency circuit that is once activated in preparation for the opening of the second circuit breaker 3 is used. The operation of the diesel generator 10 is stopped.

  As described in the third embodiment, the output signal 28 indicating the turbine trip 26 and the output signal 29 indicating the state 27 in which the first circuit breaker 6 is “ON” are input to the AND circuit 30 and output signal 31. Is established, the output signal 37 indicating the emergency diesel generator start command 36 is immediately output to the emergency diesel generator 10 to start the start. The emergency diesel generator 10 is ready to supply power after 35 seconds when given a command.

  On the other hand, when both the output signal 28 indicating the turbine trip 26 and the output signal 29 indicating the “ON” state 27 of the first circuit breaker 6 are input to the AND circuit 30, an output signal 31 is output.

  However, when the reverse power relay 15 is normally operated and the first circuit breaker opening command signal 23 is output to the first circuit breaker 6 to be opened, the AND circuit 30 displays “ The signal 29 indicating the “ON” state 27 is not input, and the output signal 31 is not established in the AND circuit 30. In this case, the second breaker opening command signal 35 is not output from the delay timer 32 and the second breaker 3 is not opened. In such a case, since the in-house power supply 7 is supplied to the auxiliary electric motor 8, there is no need to operate the emergency diesel generator 10 for backup.

  Therefore, since the output of the AND circuit 30 is not established, the output from the NOT circuit 38 is established, and the emergency diesel generator stop command signal 40 indicating the emergency diesel generator stop command 39 is output. As a result, the emergency diesel generator 10 that has been started and started operation stops.

(Function)
As a normal protection operation, when the reverse power relay 15 is activated and the first circuit breaker 6 is opened, the second circuit breaker 3 is not opened, and the output signal 31 from the AND circuit 30 is not established and the NOT circuit. At 38, the emergency diesel generator stop command signal 40 is output, and the emergency diesel generator 10 stops operating.

(effect)
By operating the reverse power relay 18 which is a normal protection operation, the first circuit breaker 6 is opened, the second circuit breaker 3 is not opened, and the operation of the backup emergency diesel generator 10 becomes unnecessary. By stopping automatically, useless electric power can be reduced, and an operation related to the operation of the operator is unnecessary, and the load is reduced.

  The above embodiments are merely examples, and various modifications can be made within the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Protection device 2 System grid 3 Second circuit breaker 4 Main transformer 5 Transmission path 6 First circuit breaker 7 In-house power supply 8 Auxiliary motor 9 In-house transformer 10 Emergency diesel generator 11 Third circuit breaker 12 Emergency oil Pressure detection pressure switch 13 Steam turbine 14 Generator 15 Reverse power relay 16 First circuit breaker open / close limit switch 18 Reverse power relay operation 20 Delay timer 22 First circuit breaker open command 26 Turbine trip 27 First circuit breaker “ON” State 30 AND circuit 32 delay timer 34 second circuit breaker open command 36 emergency diesel generator start command 38 NOT circuit 39 emergency diesel generator stop command

Claims (10)

A steam turbine;
A generator driven by the steam turbine to generate electric power;
A power transmission path for transmitting the power generated by the generator to the grid, and
A first circuit breaker provided in the power transmission path, for interrupting power transmission between the generator and the grid;
A second circuit breaker provided between the first circuit breaker and the system grid in the power transmission path, for interrupting power transmission between the generator and the system grid;
A reverse power relay for detecting occurrence of motoring operation of the steam turbine;
A protective device having a first circuit breaker opening means for opening the first circuit breaker when a first predetermined time has elapsed after the reverse power relay is activated;
With
The protective device further includes:
And a second circuit breaker opening means for opening the second circuit breaker when the steam turbine is in a trip state and the first circuit breaker is in the “on” state for a second predetermined time or longer. Power plant. The second circuit breaker opening means includes
A logic circuit that outputs a logic circuit output signal when the steam turbine is in a trip state and the first circuit breaker is in an “on” state;
When the logic circuit output signal continues for the second predetermined time or more, a delay timer that outputs a second circuit breaker opening command signal to the second circuit breaker;
Have
2. The power plant according to claim 1, wherein the second predetermined time is longer than the first predetermined time and shorter than a time during which the steam turbine allows motoring operation. The power plant further includes an emergency diesel generator used as an emergency power source,
The protection circuit further includes:
3. The power plant according to claim 2, wherein when the logic circuit outputs the logic circuit output signal, a start command is given to the emergency diesel generator.   The second predetermined time is longer than the first predetermined time and the time from when the emergency diesel generator starts to start supplying electric power, whichever is longer, and the steam turbine The power plant according to claim 3, wherein is shorter than a time during which motoring operation is allowed. The protection circuit further includes:
The power plant according to claim 3 or 4, wherein the operation of the emergency diesel generator is stopped when the logic circuit does not output the logic circuit output signal. A steam turbine;
A generator driven by the steam turbine to generate electric power;
A power transmission path for transmitting the power generated by the generator to the grid, and
A first circuit breaker provided in the power transmission path, for interrupting power transmission between the generator and the grid;
A second circuit breaker provided between the first circuit breaker and the system grid in the power transmission path, for interrupting power transmission between the generator and the system grid;
A reverse power relay for detecting occurrence of motoring operation of the steam turbine;
A protective device having a first circuit breaker opening means for opening the first circuit breaker when a first predetermined time has elapsed after the reverse power relay is activated;
A power plant protection method comprising:
The power plant according to claim 1, wherein the protection device opens the second circuit breaker when the steam turbine is in a tripped state and the first circuit breaker is in the "on" state for a second predetermined time or more. Protection method.   7. The power plant protection method according to claim 6, wherein the second predetermined time is longer than the first predetermined time and shorter than a time during which the steam turbine allows motoring operation. The power plant further includes an emergency diesel generator used as an emergency power source,
The protection circuit further
The power plant protection method according to claim 6 or 7, wherein the emergency diesel generator is activated when the steam turbine is in a trip state and the first circuit breaker is in an "on" state. .   The second predetermined time is longer than the first predetermined time and the time from when the emergency diesel generator starts to start supplying electric power, whichever is longer, and the steam turbine The method for protecting a power plant according to claim 8, wherein is shorter than a time during which motoring operation is permitted. The protection circuit further
10. The operation of the emergency diesel generator is stopped except when the steam turbine is in a trip state and the first circuit breaker is in an "on" state. Power plant protection method.

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