Nuclear power plant emergency diesel engine test mode protection method and system

Abstract

The invention relates to the technical field of nuclear power, and discloses a nuclear power plant emergency diesel generator test mode protection method and system, and the method comprises the steps: switching on a power discrimination device after an emergency diesel generator outlet circuit breaker is in a closed state and an emergency diesel generator is switched on in a test mode; judging whether the absolute value of the reverse power of the emergency diesel generator exceeds preset power or not by using a power judgment device; and when the absolute value of the reverse power exceeds the preset power, sending out an action instruction by using the power judgment device, and controlling the emergency bus incoming circuit breaker to be switched off. A power discrimination device with a direction detection function is used to discriminate whether the inverse power transmission power is overloaded, and when the inverse power transmission power is overloaded, an action instruction is sent to control the emergency bus incoming line breaker to be switched off. The emergency bus section is ensured not to lose power, and continuous operation of important loads on the emergency bus is ensured. And the situation that emergency start cannot be completed within required time in the test operation process due to power failure of the whole plant is prevented.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power technology, and in particular to a nuclear power plant emergency diesel generator test mode protection method and system. Background Art

[0002] The emergency AC power system of the emergency power system of the high-temperature gas-cooled reactor demonstration project is a power system including its auxiliary equipment and energy storage devices that is put into use to supply electric energy when the normal power supply from the power grid is unavailable. It consists of an emergency power supply (consisting of a diesel generator set, an energy storage device and auxiliary equipment) and its emergency bus distribution equipment. After the normal power supply is lost, the emergency diesel generator set is started within the required time to supply power to the emergency bus, which is used to supply power to the AC loads that allow power outages within a certain period of time. The AC loads that allow power outages within a very short period of time include: partial lighting, security power supply for the conventional island, ventilation and air conditioning in the main control room, important plant water and equipment cooling water equipment in the nuclear island, residual heat removal and heat dissipation ventilation of the spent fuel storage plant, normal and accident negative pressure ventilation systems, and emergency power supply for the fire protection system.

[0003] In order to ensure that the emergency diesel generator can supply power to the above-mentioned important loads in a short time after the normal power supply fails, it is necessary to conduct diesel generator availability tests regularly to ensure the continuous availability of the diesel generator. The tests that need to be carried out at present are the emergency diesel generator availability test and the continuous load test. Both tests require the emergency diesel generator to be operated in the test mode and in the grid-connected operation mode. If the normal power supply fails during the test, the emergency diesel generator reverses power to carry the upstream large load, and the emergency diesel generator will trip due to overload. After the emergency diesel generator trips, the state needs to be reset and the emergency diesel generator is restarted to load the emergency bus. The entire process cannot start the emergency diesel generator to supply power to the emergency bus within the limited time. Summary of the invention

[0004] In view of this, the present invention provides a test mode protection method and system for an emergency diesel generator in a nuclear power plant, so as to solve the problem that when the emergency diesel generator in the test mode faces a power failure of the normal power supply, the emergency diesel generator cannot promptly disconnect the large load upstream of the emergency bus incoming line, resulting in the emergency diesel generator being unable to supply power to the emergency bus.

[0005] The present invention provides a nuclear power plant emergency diesel generator test mode protection method, the method comprising:

[0006] After the emergency diesel generator outlet circuit breaker is in the closed state and the emergency diesel generator is put into the test mode, the power discrimination device is put into operation;

[0007] Using the power determination device to determine whether the absolute value of the reverse power of the emergency diesel generator exceeds the preset power;

[0008] When the absolute value of the reverse power exceeds the preset power, the power discrimination device is used to issue an action instruction to control the emergency bus incoming circuit breaker to open.

[0009] The present invention provides a nuclear power plant emergency diesel generator test mode protection method, which uses a power discrimination device with a direction detection function to discriminate whether the reverse power is overloaded, and issues an action command when overloaded to control the emergency bus incoming line circuit breaker to open. Ensure that the emergency bus section does not lose power and ensure the continuous operation of important loads on the emergency bus. Prevent the entire plant from losing power during the test operation and failing to complete the emergency startup within the required time.

[0010] In an optional implementation manner, using the power determination device to determine whether the absolute value of the reverse power of the emergency diesel generator exceeds a preset power includes:

[0011] Transmitting the incoming line voltage and the incoming line current of the emergency bus to the power discrimination device;

[0012] Using the power determination device to determine whether the emergency diesel generator has reverse power;

[0013] When the reverse power exists, the power determination device is used to determine whether the absolute value of the reverse power exceeds the preset power.

[0014] In an optional implementation, using the power determination device to determine whether the emergency diesel generator has reverse power includes:

[0015] Calculate the power output of the emergency diesel generator according to the incoming line voltage and the incoming line current;

[0016] When the power is less than 0, it is determined that the emergency diesel generator has reverse power;

[0017] When the power is not less than 0, it is determined that there is no reverse power in the emergency diesel generator.

[0018] In an optional embodiment, the method further includes:

[0019] Determining whether the power is credible;

[0020] When the power is reliable, executing the step of the power determination device determining whether the emergency diesel generator has reverse power;

[0021] When the power is not credible, a PT disconnection alarm signal is output, and the step of the power determination device determining whether the emergency diesel generator has reverse power is no longer performed.

[0022] The incoming line voltage is involved in the reverse power value calculation. If the PT is disconnected, the calculated power will be wrong and the emergency incoming line circuit breaker cannot be disconnected reliably. Therefore, it is necessary to determine whether the power is reliable. When the power is not reliable, a PT disconnection alarm signal is generated.

[0023] In an optional implementation manner, determining whether the power is credible includes:

[0024] When the positive-sequence incoming line voltage is less than a first set voltage and the incoming line current of any phase is greater than a first set current, it is determined that the power is unreliable;

[0025] Alternatively, when the negative-sequence incoming line voltage is greater than a second set voltage, it is determined that the power is unreliable.

[0026] In an optional embodiment, the method further includes:

[0027] After the emergency diesel engine is put into test mode, the protective pressure plate is put into operation;

[0028] After the emergency diesel engine exits the test mode, exit the protection pressure plate.

[0029] A protective pressure plate is added to the power discrimination device with direction detection function. It is only put into operation during the grid-connected operation test and is removed after the test to prevent the emergency bus from losing power due to improper operation of the equipment.

[0030] In a second aspect, the present invention provides a nuclear power plant emergency diesel generator test mode protection system, the system comprising: a power discrimination device, an emergency busbar incoming circuit breaker and an emergency diesel generator outlet circuit breaker, wherein:

[0031] The power discrimination device is put into operation after receiving the closing signal of the emergency diesel generator outlet circuit breaker and the emergency diesel generator test mode signal;

[0032] After the power determination device is put into operation, the power determination device determines whether the absolute value of the reverse power of the emergency diesel generator exceeds the preset power. When the absolute value of the reverse power exceeds the preset power, the power determination device issues an action command to control the emergency bus incoming circuit breaker to open.

[0033] The present invention provides a nuclear power plant emergency diesel generator test mode protection system, which adds a power discrimination device with a direction detection function in the control interval of the emergency bus incoming line circuit breaker. The power discrimination device with a direction detection function is used to determine whether the reverse power is overloaded, and an action command is issued when it is overloaded to control the emergency bus incoming line circuit breaker to open. Ensure that the emergency bus section does not lose power and ensure the continuous operation of important loads on the emergency bus. Prevent the entire plant from losing power during the test operation and failing to complete the emergency startup within the required time.

[0034] In an optional implementation, the power discrimination device comprises: an analog input plug-in and a CPU plug-in, wherein:

[0035] The analog input plug-in transmits the received incoming line voltage and incoming line current of the emergency bus to the CPU plug-in;

[0036] After receiving the closing signal of the emergency diesel generator outlet circuit breaker and the emergency diesel generator test mode signal, the CPU plug-in determines that the power discrimination device is put into operation, and then determines whether the absolute value of the reverse power of the emergency diesel generator exceeds the preset power. When the absolute value of the reverse power exceeds the preset power, the power discrimination device generates an action instruction to control the emergency bus incoming circuit breaker to open;

[0037] The CPU plug-in is also used to determine whether the power is credible, and when the power is not credible, a PT disconnection alarm signal is generated.

[0038] In an optional implementation, the system further includes: a multi-function card, the multi-function card is communicatively connected to the CPU plug-in, and the multi-function card is used to output action instructions and PT disconnection alarm signals.

[0039] In an optional implementation, the system further includes: a voltage transformer and a current transformer, wherein:

[0040] The voltage transformer is used to monitor the incoming line voltage of the emergency bus and transmit the incoming line voltage to the analog input plug-in;

[0041] The current transformer is used to monitor the incoming current of the emergency bus and transmit the incoming current to the analog input plug-in. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 2 is a schematic diagram of the structure of a nuclear power plant emergency diesel generator test mode protection system according to an embodiment of the present invention;

[0044] Figure 2 is a schematic diagram of the principle of a power discrimination device according to an embodiment of the present invention;

[0045] Figure 3 is an action logic diagram of a power discrimination device according to an embodiment of the present invention;

[0046] Figure 4 is a PT disconnection determination logic diagram according to an embodiment of the present invention;

[0047] Figure 5 1 is a flow chart of a nuclear power plant emergency diesel generator test mode protection method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0049] During the test, the emergency diesel generator will reverse the power supply to carry the upstream large load after the normal power supply is lost, causing the emergency diesel generator to trip due to overload. After the emergency diesel generator trips, the state needs to be reset and the emergency diesel generator to carry the emergency busbar with load is restarted. The entire process cannot start the emergency diesel generator to supply power to the emergency busbar within the limited time. Therefore, from the perspective of the safety control of the emergency diesel generator, it is necessary to optimize the control logic of the emergency diesel generator with load and grid connection operation to ensure that the emergency diesel generator can promptly get rid of the large load upstream of the emergency busbar in the case of power failure in the entire plant, and ensure that the emergency diesel generator can reliably supply power to the emergency busbar.

[0050] To this end, the present invention provides a nuclear power plant emergency diesel generator test mode protection system, such as Figure 1 As shown, it includes: a power discrimination device 1, an emergency busbar incoming circuit breaker 2 and an emergency diesel generator outlet circuit breaker 3. The power discrimination device 1 is put into operation after receiving the closing signal of the emergency diesel generator outlet circuit breaker 3 and the emergency diesel generator test mode signal. After the power discrimination device 1 is put into operation, the power discrimination device 1 determines whether the absolute value of the reverse power of the emergency diesel generator exceeds the preset power. When the absolute value of the reverse power exceeds the preset power, the power discrimination device 1 issues an action command to control the emergency busbar incoming circuit breaker 2 to open.

[0051] Specifically, Figure 1 As shown, the power discrimination device 1 with direction monitoring function is installed in the cabinet of the emergency bus incoming line circuit breaker 2. During the periodic test of the emergency diesel generator, the emergency diesel generator is started and connected to the grid through the emergency diesel generator outlet circuit breaker 3. Therefore, the closing state of the emergency diesel generator outlet circuit breaker 3 and the emergency diesel generator test mode signal are used as the conditions for judging the start of the power discrimination device 1. When the power discrimination device 1 is put into operation and determines that the absolute value of the reverse power exceeds the preset power, the power discrimination device 1 issues an action command, which acts on the emergency bus incoming line circuit breaker 2 to realize the circuit breaker opening.

[0052] The present invention provides a nuclear power plant emergency diesel generator test mode protection system, which adds a power discrimination device with a direction detection function in the control interval of the emergency bus incoming line circuit breaker. The power discrimination device with a direction detection function is used to determine whether the reverse power is overloaded, and an action command is issued when it is overloaded to control the emergency bus incoming line circuit breaker to open. Ensure that the emergency bus section does not lose power and ensure the continuous operation of important loads on the emergency bus. Prevent the entire plant from losing power during the test operation and failing to complete the emergency startup within the required time.

[0053] In an optional embodiment, if Figure 2 As shown, the power discrimination device 1 includes: an analog input plug-in and a CPU plug-in. The analog input plug-in transmits the received incoming line voltage and incoming line current of the emergency bus to the CPU plug-in. After receiving the closing signal of the emergency diesel generator outlet circuit breaker 3 and the emergency diesel generator test mode signal, the CPU plug-in determines that the power discrimination device 1 is put into operation, and then determines whether the absolute value of the reverse power of the emergency diesel generator exceeds the preset power. When the absolute value of the reverse power exceeds the preset power, the power discrimination device 1 generates an action instruction to control the emergency bus incoming line circuit breaker 2 to open. The CPU plug-in is also used to determine whether the power is credible. When the power is not credible, a PT disconnection alarm signal is generated.

[0054] Specifically, after the CPU plug-in receives the incoming line voltage and current of the emergency bus transmitted by the analog input plug-in, it performs analog-to-digital conversion on the incoming line voltage and current, and then transmits them to the ARM microprocessor for logical judgment to generate action instructions or PT line break alarm signals.

[0055] Among them, the judgment logic in the CPU plug-in is as follows Figure 3 As shown, the closing signal of the emergency diesel generator outlet circuit breaker 3 and the emergency diesel generator test mode signal are used as the conditions for determining the start of the power determination device 1. After the power determination device 1 is put into operation, it is determined whether the power output of the emergency diesel generator is less than 0 and whether the absolute value of the power is greater than the preset power |Pset|. When the emergency diesel generator outputs reverse power and the absolute value of the reverse power is greater than the preset power |Pset|, the power determination device 1 generates an action instruction to control the emergency busbar incoming circuit breaker 2 to open.

[0056] In addition, the incoming line voltage is involved in the reverse power value calculation. If the PT is disconnected, the calculated power will be wrong and the emergency incoming line circuit breaker cannot be disconnected reliably. Therefore, it is necessary to determine whether the power is reliable. When the power is not reliable, a PT disconnection alarm signal is generated.

[0057] Specific alarm logic is as follows: Figure 4 As shown, when the positive sequence incoming line voltage U 正序 Less than the first set voltage Uset1 and any phase incoming current I MAX(Any phase) is greater than the first set current (rated current I N 5%), a PT disconnection alarm will be issued, or the negative sequence incoming line voltage U 负序 When the voltage is greater than the second set voltage Uset2, a PT disconnection alarm will also be issued.

[0058] In an optional embodiment, if Figure 2 As shown, the power determination device 1 further includes: a multi-function card.

[0059] Specifically, the multi-function card is connected to the CPU plug-in for communication, and the multi-function card is used to output action instructions and PT disconnection alarm signals.

[0060] In an optional embodiment, if Figure 1 As shown, the nuclear power plant emergency diesel generator test mode protection system also includes: a voltage transformer 4 and a current transformer 5. Among them, the voltage transformer 4 is used to monitor the incoming line voltage of the emergency bus and transmit the incoming line voltage to the analog input plug-in. The current transformer 5 is used to monitor the incoming line current of the emergency bus and transmit the incoming line current to the analog input plug-in.

[0061] Specifically, the current transformer 5 is installed between the transformer and the emergency busbar incoming line, and the transformer points to the emergency busbar as the positive direction of the current. The voltage transformer 4 is used to monitor the emergency busbar incoming line voltage and is installed in the emergency busbar incoming line circuit breaker 2 cabinet. Among them, the voltage transformer 4 has a transformation ratio of 380 / 100V, and the current transformer 5CT has a transformation ratio of 2500 / 5A.

[0062] In this embodiment, a nuclear power plant emergency diesel generator test mode protection method is also provided. Figure 5 As shown, the following steps are included:

[0063] Step S1, after the emergency diesel generator outlet circuit breaker is in a closed state and the emergency diesel generator is put into a test mode, the power determination device is put into operation.

[0064] Specifically, during the periodic test of the emergency diesel generator, the emergency diesel generator is started and connected to the grid through the emergency diesel generator outlet circuit breaker. Therefore, the closing state of the emergency diesel generator outlet circuit breaker and the emergency diesel generator test mode signal are used as the conditions for determining the start of the power determination device.

[0065] Step S2: using a power determination device to determine whether the absolute value of the reverse power of the emergency diesel generator exceeds a preset power.

[0066] Specifically, when the emergency diesel generator is in grid-connected test operation, a power determination device with a direction detection function is used to determine whether the reverse power exceeds a preset power |Pset|.

[0067] Step S3: When the absolute value of the reverse power exceeds the preset power, the power discrimination device is used to issue an action command to control the emergency bus incoming circuit breaker to open.

[0068] Specifically, when the power discrimination device with direction detection function determines that the reverse power is overloaded, the power discrimination device issues an action command to control the emergency bus incoming line circuit breaker to open. Ensure that the emergency bus section does not lose power and ensure the continuous operation of important loads on the emergency bus. Prevent the whole plant from losing power during the test operation and failing to complete the emergency start within the required time.

[0069] The present invention provides a nuclear power plant emergency diesel generator test mode protection method, which uses a power discrimination device with a direction detection function to discriminate whether the reverse power is overloaded, and issues an action command when overloaded to control the emergency bus incoming line circuit breaker to open. Ensure that the emergency bus section does not lose power and ensure the continuous operation of important loads on the emergency bus. Prevent the entire plant from losing power during the test operation and failing to complete the emergency startup within the required time.

[0070] In an optional implementation, step S2 includes the following steps:

[0071] Step S21, transmitting the incoming line voltage and the incoming line current of the emergency bus to the power determination device.

[0072] Specifically, the voltage transformer transmits the monitored incoming line voltage to the analog input plug-in. The current transformer transmits the monitored incoming line current to the analog input plug-in. The analog input plug-in transmits the received incoming line voltage and incoming line current of the emergency bus to the CPU plug-in.

[0073] Step S22, using a power determination device to determine whether the emergency diesel generator has reverse power.

[0074] Specifically, the above step S22 includes:

[0075] Step S221, calculating the output power of the emergency diesel generator according to the incoming line voltage and the incoming line current.

[0076] Step S222: when the power is less than 0, it is determined that the emergency diesel generator has reverse power.

[0077] Step S223: when the power is not less than 0, it is determined that there is no reverse power in the emergency diesel generator.

[0078] In the embodiment of the present invention, after the CPU plug-in receives the incoming line voltage and incoming line current of the emergency bus transmitted by the analog input plug-in, it performs analog-to-digital conversion on the incoming line voltage and incoming line current, and then transmits them to the ARM microprocessor for logical judgment. When the power output of the emergency diesel generator is less than 0, it means that the emergency diesel generator is reversely transmitting power to carry a large upstream load.

[0079] Step S23: When reverse power exists, a power determination device is used to determine whether the absolute value of the reverse power exceeds a preset power.

[0080] Specifically, according to Figure 3 As shown in the logic judgment diagram, when the emergency diesel generator outputs reverse power and the absolute value of the reverse power is greater than the preset power |Pset|, the power discrimination device generates an action command to control the emergency bus incoming circuit breaker to open.

[0081] In an optional implementation manner, the nuclear power plant emergency diesel generator test mode protection method further includes:

[0082] Step S224, determining whether the power is credible.

[0083] Step S225, when it is determined that the power is reliable, the power determination device is executed to determine whether there is reverse power in the emergency diesel generator.

[0084] Step S226, when it is determined that the power is unreliable, a PT disconnection alarm signal is output, and the step of the power identification device identifying whether there is reverse power in the emergency diesel generator is no longer executed.

[0085] Specifically, the incoming line voltage participates in the reverse power value calculation. If the PT is disconnected, the calculated power will be wrong and the emergency incoming line circuit breaker cannot be disconnected reliably. Therefore, it is necessary to determine whether the power is reliable. When the power is not reliable, a PT disconnection alarm signal is generated. Determining whether the power is reliable includes the following process:

[0086] Step S2241: when the positive-sequence incoming line voltage is less than the first set voltage and the incoming line current of any phase is greater than the first set current, it is determined that the power is unreliable.

[0087] Step S2242, or when the negative sequence incoming line voltage is greater than the second set voltage, it is determined that the power is unreliable.

[0088] In the embodiment of the present invention, when the positive sequence incoming line voltage U 正序 Less than the first set voltage Uset1 and any phase incoming current I MAX (Any phase) is greater than the first set current (rated current I N 5%), the power is judged to be unreliable and a PT disconnection alarm is issued, or the negative sequence incoming line voltage U 负序 When it is greater than the second set voltage Uset2, the power is judged to be unreliable and a PT disconnection alarm is also issued.

[0089] In an optional implementation manner, the nuclear power plant emergency diesel generator test mode protection method further includes:

[0090] Step S4, after the emergency diesel engine is put into the test mode, the protection pressure plate is put into operation.

[0091] Step S5, after the emergency diesel engine exits the test mode, the protection pressure plate is exited.

[0092] Specifically, a protective pressure plate is added to the power discrimination device with a direction detection function. The protective pressure plate is only put into operation during the grid-connected operation test and is withdrawn after the test to prevent the emergency bus from losing power due to improper operation of the equipment.

[0093] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A nuclear power plant emergency diesel generator test mode protection method, characterized in that: The method comprises: After the emergency diesel generator outlet circuit breaker is in the closed state and the emergency diesel generator is put into the test mode, the power discrimination device is put into operation; Using the power determination device to determine whether the absolute value of the reverse power of the emergency diesel generator exceeds the preset power; When the absolute value of the reverse power exceeds the preset power, the power discrimination device is used to issue an action instruction to control the emergency bus incoming circuit breaker to open.

2. The nuclear power plant emergency diesel generator test mode protection method according to claim 1, characterized in that: Using the power determination device to determine whether the absolute value of the reverse power of the emergency diesel generator exceeds the preset power includes: Transmitting the incoming line voltage and the incoming line current of the emergency bus to the power discrimination device; Using the power determination device to determine whether the emergency diesel generator has reverse power; When the reverse power exists, the power determination device is used to determine whether the absolute value of the reverse power exceeds the preset power.

3. The nuclear power plant emergency diesel generator test mode protection method according to claim 2, characterized in that: Using the power determination device to determine whether the emergency diesel generator has reverse power includes: Calculate the power output of the emergency diesel generator according to the incoming line voltage and the incoming line current; When the power is less than 0, it is determined that the emergency diesel generator has reverse power; When the power is not less than 0, it is determined that there is no reverse power in the emergency diesel generator.

4. The nuclear power plant emergency diesel generator test mode protection method according to claim 3, characterized in that: The method further comprises: Determining whether the power is credible; When the power is reliable, executing the step of the power determination device determining whether the emergency diesel generator has reverse power; When the power is not credible, a PT disconnection alarm signal is output, and the step of the power determination device determining whether the emergency diesel generator has reverse power is no longer performed.

5. The nuclear power plant emergency diesel generator test mode protection method according to claim 4, characterized in that: Determining whether the power is credible includes: When the positive-sequence incoming line voltage is less than the first set voltage and the incoming line current of any phase is greater than the first set current, it is determined that the power is unreliable; Alternatively, when the negative-sequence incoming line voltage is greater than the second set voltage, it is determined that the power is unreliable.

6. The nuclear power plant emergency diesel generator test mode protection method according to claim 1, characterized in that: The method further comprises: After the emergency diesel engine is put into test mode, the protective pressure plate is put into operation; After the emergency diesel engine exits the test mode, exit the protection pressure plate.

7. A nuclear power plant emergency diesel generator test mode protection system, characterized in that: The system includes: a power discrimination device, an emergency busbar incoming circuit breaker and an emergency diesel generator outlet circuit breaker, wherein: The power discrimination device is put into operation after receiving the closing signal of the emergency diesel generator outlet circuit breaker and the emergency diesel generator test mode signal; After the power determination device is put into operation, the power determination device determines whether the absolute value of the reverse power of the emergency diesel generator exceeds the preset power. When the absolute value of the reverse power exceeds the preset power, the power determination device issues an action command to control the emergency bus incoming circuit breaker to open.

8. The nuclear power plant emergency diesel generator test mode protection system according to claim 7, characterized in that: The power discrimination device comprises: an analog input plug-in and a CPU plug-in, wherein: The analog input plug-in transmits the received incoming line voltage and incoming line current of the emergency bus to the CPU plug-in; After receiving the closing signal of the emergency diesel generator outlet circuit breaker and the emergency diesel generator test mode signal, the CPU plug-in determines that the power discrimination device is put into operation, and then determines whether the absolute value of the reverse power of the emergency diesel generator exceeds the preset power. When the absolute value of the reverse power exceeds the preset power, the power discrimination device generates an action instruction to control the emergency bus incoming circuit breaker to open; The CPU plug-in is also used to determine whether the power is credible, and when the power is not credible, a PT disconnection alarm signal is generated.

9. The nuclear power plant emergency diesel generator test mode protection system according to claim 8, characterized in that: The system further comprises: a multi-function card, the multi-function card is communicatively connected with the CPU plug-in, and the multi-function card is used for outputting action instructions and PT disconnection alarm signals.

10. The nuclear power plant emergency diesel generator test mode protection system according to claim 8, characterized in that: The system further comprises: a voltage transformer and a current transformer, wherein: The voltage transformer is used to monitor the incoming line voltage of the emergency bus and transmit the incoming line voltage to the analog input plug-in; The current transformer is used to monitor the incoming current of the emergency bus and transmit the incoming current to the analog input plug-in.

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