Loss of excitation protection method and system for control rod power supply system

Abstract

The present invention relates to a demagnetization protection method and system for a control rod power system. This embodiment of the demagnetization protection method includes obtaining the output voltage and output current of two generator trains in the control rod power system; performing a demagnetization protection step for each generator train, wherein the demagnetization protection step comprises determining whether the excitation system of the generator train has failed based on the output voltage and output current of the generator train and the output voltage and output current of the other generator train, and disconnecting the output switch of the generator train if a failure occurs. This technical solution, which collects and analyzes the current and voltage parameters of the generators for demagnetization protection, can prevent malfunction or misoperation of the generator output switches, thereby improving the reliability of the control rod power system and ensuring redundancy of the control rod power system.

Description

Technical Field

[0001] The present invention relates to the field of relay protection, and in particular to a demagnetization protection method and system for a control rod power supply system. Background Art

[0002] The control rod power system (RAM) of a nuclear power plant reactor is used to power the drive mechanism of the control rods and plays a vital role in the operation of the nuclear power plant. Figure 1 As shown, the control rod power supply system consists of two sets of grid-connected generators, and each set of generators is excited by a corresponding excitation system. Moreover, in the excitation system, the excitation regulation device automatically adjusts the excitation current through the real-time voltage and current data collected by the voltage transformer and current transformer.

[0003] The existing excitation system demagnetization protection is a simple electromagnetic protection, which only determines whether there is demagnetization based on the size of the generator rotor current (the excitation current output by the excitation system). If the excitation current is lower than a certain value after the generator is running, the demagnetization protection will trip to disconnect the generator train.

[0004] However, in nuclear power plant operations, it's common to find that a tripped generator appears to be operating normally. This not only deprives the control rod power system of redundancy, but also increases the voltage in the control rod drive mechanism due to the tripping of a normally operating generator. Consequently, existing de-excitation protection devices suffer from significant design flaws, resulting in poor reliability of the control rod power system. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a demagnetization protection method and system for a control rod power supply system in view of the serious design defects of the demagnetization protection device in the prior art.

[0006] The technical solution adopted by the present invention to solve the technical problem is to construct a demagnetization protection method for a control rod power supply system, comprising:

[0007] Obtain the output voltage and output current of the two generators of the control rod power system;

[0008] A demagnetization protection step is performed for each train of generators, and the demagnetization protection step is as follows: based on the output voltage and output current of the train of generators and the output voltage and output current of the other train of generators, it is determined whether the excitation system of the train of generators has failed, and when a failure occurs, the output switch of the train of generators is disconnected.

[0009] Preferably, the demagnetization protection step includes:

[0010] Determine whether the main circuit of the excitation regulating device of the generator train is faulty based on the output voltage and output current of the generator train, and disconnect the output switch of the generator train if the main circuit of the excitation regulating device is faulty;

[0011] Based on the output voltage and output current of the current train generator and the output voltage and output current of the other train generator, it is determined whether the excitation regulation device of the current train generator and its sampling circuit and output circuit are faulty. When the excitation regulation device itself fails, or the sampling circuit or output circuit of the excitation regulation device fails, the output switch of the current train generator is disconnected.

[0012] Preferably, judging whether the main circuit of the excitation regulating device of the generator train is faulty based on the output voltage and output current of the generator train includes:

[0013] Calculate the admittance of the generator in this train based on its output voltage and output current;

[0014] It is determined whether the generator of the train is in a demagnetization state according to the calculated admittance, and if in the demagnetization state, it is determined that a main circuit fault occurs in the excitation regulating device of the generator of the train.

[0015] Preferably, judging whether the excitation regulation device of the generator train and its sampling circuit and output circuit are faulty based on the output voltage and output current of the generator train and the output voltage and output current of the generator train of another generator train includes:

[0016] Calculate the reactive power of the generators in this train based on their output voltage and output current;

[0017] Calculate the reactive power of another generator set based on its output voltage and output current;

[0018] Determine whether the output voltage of the generator in this column is greater than a first preset value, whether the reactive power of the generator in this column is greater than a second preset value, and whether the reactive power of the generator in another column is less than a third preset value; and when the output voltage of the generator in this column is greater than the first preset value, the reactive power of the generator in this column is greater than the second preset value, and the reactive power of the generator in another column is less than the third preset value, determine that the excitation regulation device of the generator in this column itself is faulty, or that the sampling circuit or the output circuit of the excitation regulation device is faulty.

[0019] The present invention also constructs a demagnetization protection system for a control rod power supply system, comprising a data acquisition module and a demagnetization protection module corresponding to each generator train, wherein:

[0020] The data acquisition module is used to obtain the output voltage and output current of the two generators of the control rod power system;

[0021] The demagnetization protection module is used to determine whether the excitation system of the current generator train has failed based on the output voltage and output current of the current generator train and the output voltage and output current of the other generator trains, and to disconnect the output switch of the current generator train when a failure occurs.

[0022] Preferably, the demagnetization protection module includes:

[0023] The first protection unit is configured to determine whether a main circuit of an excitation regulating device of the generator train is faulty based on the output voltage and output current of the generator train, and to disconnect an output switch of the generator train when the main circuit of the excitation regulating device is faulty.

[0024] The second protection unit is used to determine whether the excitation regulation device and its sampling circuit and output circuit of the generator in this column are faulty based on the output voltage and output current of the generator in this column and the output voltage and output current of the generator in another column, and to disconnect the output switch of the generator in this column when the excitation regulation device itself fails or the sampling circuit or output circuit of the excitation regulation device fails.

[0025] Preferably, the first protection unit includes:

[0026] A first calculation subunit is used to calculate the admittance of the generators in this column according to the output voltage and output current of the generators in this column;

[0027] The first judgment subunit is used to judge whether the generator of this column is in a demagnetization state according to the calculated admittance;

[0028] The first control subunit is used to determine that a main circuit fault occurs in the excitation regulating device of the train of generators when the train of generators is in a demagnetized state, and to disconnect the output switch of the train of generators.

[0029] Preferably, the second protection unit includes:

[0030] The second calculation subunit is configured to calculate the reactive power of the generators in the current column based on the output voltage and output current of the generators in the current column; and to calculate the reactive power of the generators in the current column based on the output voltage and output current of the generators in the current column;

[0031] The second judgment subunit is used to judge whether the output voltage of the generator in the current train is greater than a first preset value; judge whether the reactive power of the generator in the current train is greater than a second preset value; and judge whether the reactive power of the generator in the other train is less than a third preset value;

[0032] The second control subunit is used to determine that the excitation regulation device of the current column of generators has a fault, or that the sampling circuit or the output circuit of the excitation regulation device has a fault, and disconnect the output switch of the current column of generators when the output voltage of the current column of generators is greater than a first preset value, the reactive power of the current column of generators is greater than a second preset value, and the reactive power of the other column of generators is less than a third preset value.

[0033] Preferably, the second control subunit includes a logic AND gate, and the first input end of the logic AND gate inputs a first signal, the second input end of the logic AND gate inputs a second signal, the third input end of the logic AND gate inputs a third signal, and the output end of the logic AND gate outputs a switch control signal, and the switch control signal is used to control the output switch of this column of generators, wherein the first signal is high when the output voltage of this column of generators is greater than a first preset value, and is low otherwise; the second signal is high when the reactive power of this column of generators is greater than a second preset value, and is low otherwise; the third signal is high when the reactive power of another column of generators is less than a third preset value, and is low otherwise.

[0034] The present invention also constructs a demagnetization protection system for a control rod power supply system, comprising a processor, wherein the processor implements the steps of the demagnetization protection method described above when executing a stored computer program.

[0035] In the technical solution provided by the present invention, demagnetization protection is performed by collecting and analyzing the current and voltage parameters of the generator, thereby avoiding malfunction and misoperation of the generator output switch, improving the reliability of the control rod power supply system, and ensuring the redundancy of the control rod power supply system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without inventive efforts. In the drawings:

[0037] Figure 1 This is a schematic diagram of the power supply system for the control rod power supply;

[0038] Figure 2 This is a flow chart of a first embodiment of a method for protecting a control rod power supply system from demagnetization according to the present invention;

[0039] Figure 3 This is a schematic diagram of the admittance setting principle of the demagnetization protection of the present invention;

[0040] Figure 4 1 is a logical structure diagram of a first embodiment of a demagnetization protection system for a control rod power supply system according to the present invention;

[0041] Figure 5 yes Figure 4 Logic structure diagram of the second control subunit embodiment 1 of the second protection unit. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] First, with the reactor shut down, simulation tests were conducted on the two generators in the control rod power system under various demagnetization and partial demagnetization conditions. The demagnetization protection behavior and changes in parameters such as reactive power, voltage, and current were observed. The test results are shown in Table 1:

[0044]

[0045]

[0046] Table 1

[0047] According to the test results, when the excitation system of a generator fails, the voltage and current of the generator train will change, and may also cause the voltage and current of another generator train to change. Therefore, by collecting the current and voltage parameters of the two generator trains and performing configuration analysis based on the current and voltage of the two generator trains, it can be determined whether to disconnect the output switch of the generator train.

[0048] Figure 2 1 is a flow chart of a first embodiment of a method for protecting a control rod power supply system from demagnetization according to the present invention. The method for protecting a control rod power supply system according to the present invention includes the following steps:

[0049] Step S10: Obtain the output voltage and output current of the two generators of the control rod power system;

[0050] Step S20. For each train of generators, a demagnetization protection step is performed, and the demagnetization protection step is: based on the output voltage and output current of the train of generators and the output voltage and output current of another train of generators, it is determined whether the excitation system of the train of generators has a fault, and when a fault occurs, the output switch of the train of generators is disconnected.

[0051] In the technical solution of this embodiment, demagnetization protection is performed by analyzing the current and voltage parameters of the generator, thereby avoiding malfunction and misoperation of the generator output switch and improving the reliability of the control rod power supply system.

[0052] Furthermore, from the test results shown in Table 1, two different types of demagnetization protection can be performed for the following two working conditions:

[0053] 1. In the event of demagnetization of the main circuit of the excitation control device, the admittance setting principle can be used for protection;

[0054] 2. Due to the particularity of the phase compound excitation system of the generator in the control rod power system, if the excitation regulator (AVR) itself fails, or its sampling circuit or output circuit fails, it will cause the other normal generator to trip. At this time, the reactive power and voltage of the faulty generator can be increased, while the generators of the non-faulty generator can run in phase leading mode for protection.

[0055] Based on the above analysis, in an optional embodiment, the demagnetization protection step in step S20 specifically includes:

[0056] Step S21. Determine whether the main circuit of the excitation regulating device of the generator train is faulty based on the output voltage and output current of the generator train. If the main circuit of the excitation regulating device is faulty, disconnect the output switch of the generator train.

[0057] Step S22. Based on the output voltage and output current of the current train generator and the output voltage and output current of the other train generator, determine whether the excitation regulation device and its sampling circuit and output circuit of the current train generator are faulty, and disconnect the output switch of the current train generator when the excitation regulation device itself fails, or when the sampling circuit or output circuit of the excitation regulation device fails.

[0058] Furthermore, with respect to the first type of demagnetization protection, in a specific embodiment, in step S21, whether the main circuit of the excitation regulation device of the train of generators is faulty can be determined in the following manner: the admittance of the train of generators is calculated based on the output voltage and output current of the train of generators; whether the train of generators is in a demagnetization state is determined based on the calculated admittance, and if in the demagnetization state, it is determined that the main circuit of the excitation regulation device of the train of generators is faulty.

[0059] In a specific embodiment, combining Figure 3The vertical axis G represents conductance, and the horizontal axis B represents susceptance. Furthermore, the generator's static stability curve is simulated by combining two characteristic curves (Characteristic 1 and Characteristic 2) with the same delay. These two characteristic curves are at different distances from the origin and have different inclination angles α1 and α2. If the calculated admittance exceeds Characteristic 1 or Characteristic 2, it indicates that the generator is currently experiencing slight demagnetization and has entered the static stability boundary. In this case, a trip command can be issued after a delay. There is also a Characteristic 3 curve. When the admittance value exceeds this characteristic curve, it indicates that the generator has developed a severe demagnetization state and has entered the dynamic stability boundary. Therefore, in this case, a trip command should be issued immediately.

[0060] Further, regarding the second type of demagnetization protection, in a specific embodiment, in step S22, whether the excitation regulation device and its sampling circuit and output circuit of the current train of generators are faulty can be determined in the following manner: the reactive power of the current train of generators is calculated based on the output voltage and output current of the current train of generators; the reactive power of the other train of generators is calculated based on the output voltage and output current of the other train of generators; it is determined whether the output voltage of the current train of generators is greater than a first preset value (for example, whether the terminal voltage of the current train of generators is greater than 1.05 times the rated terminal voltage), whether the reactive power of the current train of generators is greater than a second preset value (for example, whether the reactive power of the current train of generators is greater than 50 kvar), and whether the reactive power of the other train of generators is less than a third preset value (for example, whether the reactive power of the other train of generators is less than -50 kvar); and when the output voltage of the current train of generators is greater than the first preset value, the reactive power of the current train of generators is greater than the second preset value, and the reactive power of the other train of generators is less than the third preset value, it is determined that the excitation regulation device of the current train of generators itself is faulty, or the sampling circuit or output circuit of the excitation regulation device is faulty.

[0061] Regarding the second type of demagnetization protection, it should be noted that Figure 1As shown in Table 1, when there is a fault in the excitation regulation device of the generator in Column A or its sampling circuit and output circuit (Case 4 in Table 1), the excitation negative compensation link of the generator in Column A is zero, the terminal voltage of the generator in Column A increases, and a large amount of reactive power is generated. The generator in Column B can only operate in the leading power factor mode to absorb the reactive power generated by the generator in Column A. Therefore, the generator in Column B starts to lose excitation. After losing excitation, the reactive power changes from positive to negative. When the reactive power is less than -100 kVar, the loss-of-excitation protection of Column B starts (Exc < picked up = 1). Then the reactive power continues to decrease. When it drops to -133 kVar, the rate of decrease slows down. When it reaches the maximum of -138 kVar, the reactive power starts to slowly recover and finally stabilizes at around -133 kVar until the loss-of-excitation protection trips. That is to say, the test results show that when the two columns of generators are operating in parallel normally, if there is a fault in the excitation regulation device of one column of generators or its sampling and output circuits, the terminal voltage of the two columns of generators increases from the rated voltage of 260 V to 288 V (1.1Un). The reactive power of the generator in the faulty column increases, and the reactive power it generates is absorbed by the generator in the fault-free column. After the generator in the fault-free column operates in the leading power factor mode, the loss-of-excitation protection of the generator acts, and the generator in the fault-free column stops operating.

[0062] Based on the above analysis, in this embodiment, a loss-of-excitation protection design concept is constructed based on the change in the reactive power and voltage of the two columns of generators, to solve the protection problem in the case where a fault in the excitation regulation device (AVR) of the generator or its sampling circuit and output circuit may cause the loss of excitation of another column of normally operating generators. Since the traditional loss-of-excitation protection will trip the normally operating generator under such working conditions and cannot cut off the generator in the faulty column, it may lead to the shutdown of the reactor. After a large number of on-site tests and simulation tests, by using the change in the voltage and reactive power parameters of the two columns of generators under such working conditions, it is realized that the normally operating generator will not be wrongly tripped under any of the above loss-of-excitation conditions of the generator.

[0063] Figure 4 It is the logic structure diagram of the first embodiment of the loss-of-excitation protection system of the control rod power supply system of the present invention. The loss-of-excitation protection system of this embodiment includes a data acquisition module 10 and loss-of-excitation protection modules 20, 20' corresponding to each column of generators. Among them, the data acquisition module 10 is used to acquire the output voltage and output current of the two columns of generators of the control rod power supply system; the loss-of-excitation protection modules 20, 20' are used to judge whether there is a fault in the excitation system of the generator in this column according to the output voltage and output current of the generator in this column and the output voltage and output current of the generator in the other column, and disconnect the outlet switch of the generator in this column when a fault occurs.

[0064] Furthermore, the demagnetization protection module 20 includes a first protection unit 21 and a second protection unit 22. The first protection unit 21 is used to determine whether the main circuit of the excitation regulation device of the current generator train is faulty based on the output voltage and output current of the current generator train, and to disconnect the output switch of the current generator train when the main circuit of the excitation regulation device fails. The second protection unit 22 is used to determine whether the excitation regulation device and its sampling circuit and output circuit of the current generator train and another generator train are faulty based on the output voltage and output current of the current generator train and the output voltage and output current of the current generator train, and to disconnect the output switch of the current generator train when the excitation regulation device itself fails or the sampling circuit or output circuit of the excitation regulation device fails. It should be understood that the logical structure of the demagnetization protection module 20′ is the same as that of the demagnetization protection module 20 and will not be described in detail here. In this embodiment, the first protection unit 21 uses the admittance setting principle to provide protection in the event of demagnetization of the main circuit of the excitation regulation device. The second protection unit 22 uses the reactive power and voltage increase of the faulty generator and the leading phase operation of the non-faulty generator to provide protection in the event of a fault in the excitation regulation device (AVR) itself or a fault in its sampling circuit or output circuit that will cause another normal generator to trip.

[0065] Furthermore, the first protection unit 21 includes a first calculation subunit, a first judgment subunit and a first control subunit, wherein the first calculation subunit is used to calculate the admittance of the generator in this column according to the output voltage and output current of the generator in this column; the first judgment subunit is used to judge whether the generator in this column is in a demagnetization state according to the calculated admittance; the first control subunit is used to determine that the main circuit of the excitation regulation device of the generator in this column is faulty when the generator in this column is in a demagnetization state, and disconnect the output switch of the generator in this column.

[0066] Furthermore, the second protection unit 22 includes a second calculation subunit, a second judgment subunit and a second control subunit, wherein the second calculation subunit is used to calculate the reactive power of the generator in this column based on the output voltage and output current of the generator in this column, and calculate the reactive power of the generator in another column based on the output voltage and output current of the generator in this column; the second judgment subunit is used to judge whether the output voltage of the generator in this column is greater than a first preset value, judge whether the reactive power of the generator in this column is greater than a second preset value, and judge whether the reactive power of the generator in another column is less than a third preset value; the second control subunit is used to determine that the excitation regulation device of the generator in this column itself is faulty, or that the sampling circuit or output circuit of the excitation regulation device is faulty, and disconnect the output switch of the generator in this column when the output voltage of the generator in this column is greater than the first preset value, the reactive power of the generator in this column is greater than the second preset value, and the reactive power of the generator in another column is less than the third preset value.

[0067] Figure 5 yes Figure 4 The logical structure diagram of the second control subunit embodiment 1 of the second protection unit in the embodiment, the second control subunit includes a logic AND gate A1, and the first input end of the logic AND gate A1 inputs the first signal S1, the second input end of the logic AND gate A1 inputs the second signal S2, the third input end of the logic AND gate A1 inputs the third signal S3, and the output end of the logic AND gate A1 outputs a switch control signal, which is used to control the output switch of this column of generators, wherein the first signal S1 is high when the output voltage of this column of generators is greater than a first preset value (for example, U1>1.05Un, Un is the rated terminal voltage), and is low otherwise; the second signal S2 is high when the reactive power of this column of generators is greater than a second preset value (for example, Q1>50kavr), and is low otherwise; the third signal S3 is high when the reactive power of another column of generators is less than a third preset value (for example, Q2<-50kavr), and is low otherwise.

[0068] The present invention also constructs a demagnetization protection system for a control rod power supply system, the demagnetization protection system comprising a processor, and the processor implements the steps of any one of the above demagnetization protection methods when executing a stored computer program.

[0069] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be encompassed within the scope of the claims.

Claims

1. A method for protecting a control rod power supply system from demagnetization, characterized in that: include: Obtain the output voltage and output current of the two generators of the control rod power system; For each train of generators, a demagnetization protection step is performed, and the demagnetization protection step includes: judging whether the excitation system of the train of generators has a fault based on the output voltage and output current of the train of generators and the output voltage and output current of the other train of generators, and disconnecting the output switch of the train of generators if a fault occurs; The demagnetization protection step includes: Determine whether the main circuit of the excitation regulating device of the generator train is faulty based on the output voltage and output current of the generator train, and disconnect the output switch of the generator train if the main circuit of the excitation regulating device is faulty; Based on the output voltage and output current of the current generator and the output voltage and output current of the other generator, determine whether the excitation regulation device and its sampling circuit and output circuit of the current generator are faulty, and disconnect the output switch of the current generator when the excitation regulation device itself fails or the sampling circuit or output circuit of the excitation regulation device fails; The method of determining whether the excitation regulation device and its sampling circuit and output circuit of the generator in the current train are faulty based on the output voltage and output current of the generator in the current train and the output voltage and output current of the generator in the other train includes: Calculate the reactive power of the generators in this train based on their output voltage and output current; Calculate the reactive power of another generator set based on its output voltage and output current; Determine whether the output voltage of the generator in this column is greater than a first preset value, whether the reactive power of the generator in this column is greater than a second preset value, and whether the reactive power of the generator in another column is less than a third preset value; and when the output voltage of the generator in this column is greater than the first preset value, the reactive power of the generator in this column is greater than the second preset value, and the reactive power of the generator in another column is less than the third preset value, determine that the excitation regulation device of the generator in this column itself is faulty, or that the sampling circuit or the output circuit of the excitation regulation device is faulty.

2. The method for protecting the control rod power supply system from demagnetization according to claim 1, wherein: Based on the output voltage and output current of the generator in this train, determine whether the main circuit of the excitation regulation device of the generator in this train is faulty, including: Calculate the admittance of the generator in this train based on its output voltage and output current; It is determined whether the generator of the train is in a demagnetization state according to the calculated admittance, and if in the demagnetization state, it is determined that a main circuit fault occurs in the excitation regulating device of the generator of the train.

3. A control rod power system demagnetization protection system, characterized in that: It includes a data acquisition module and a demagnetization protection module corresponding to each generator, wherein: The data acquisition module is used to obtain the output voltage and output current of the two generators of the control rod power system; The demagnetization protection module is used to determine whether the excitation system of the generator in the current train has failed based on the output voltage and output current of the generator in the current train and the output voltage and output current of the generator in another train, and to disconnect the output switch of the generator in the current train when a failure occurs. The demagnetization protection module includes: The first protection unit is configured to determine whether a main circuit of an excitation regulating device of the generator train is faulty based on the output voltage and output current of the generator train, and to disconnect an output switch of the generator train when the main circuit of the excitation regulating device is faulty. The second protection unit is configured to determine whether the excitation regulation device and its sampling circuit and output circuit of the generator in the current train are faulty based on the output voltage and output current of the current train generator and the output voltage and output current of the generator in the other train generator, and to disconnect the output switch of the generator in the current train generator when the excitation regulation device itself fails or the sampling circuit or output circuit of the excitation regulation device fails; The second protection unit includes: The second calculation subunit is configured to calculate the reactive power of the generators in the current column based on the output voltage and output current of the generators in the current column; and to calculate the reactive power of the generators in the current column based on the output voltage and output current of the generators in the current column; The second judgment subunit is used to judge whether the output voltage of the generator in the current train is greater than a first preset value; judge whether the reactive power of the generator in the current train is greater than a second preset value; and judge whether the reactive power of the generator in the other train is less than a third preset value; The second control subunit is used to determine that the excitation regulation device of the current column of generators has a fault, or that the sampling circuit or the output circuit of the excitation regulation device has a fault, and disconnect the output switch of the current column of generators when the output voltage of the current column of generators is greater than a first preset value, the reactive power of the current column of generators is greater than a second preset value, and the reactive power of the other column of generators is less than a third preset value.

4. The control rod power supply system demagnetization protection system according to claim 3, characterized in that: The first protection unit includes: A first calculation subunit is used to calculate the admittance of the generators in this column according to the output voltage and output current of the generators in this column; The first judgment subunit is used to judge whether the generator of this column is in a demagnetization state according to the calculated admittance; The first control subunit is used to determine that a main circuit fault occurs in the excitation regulating device of the train of generators when the train of generators is in a demagnetized state, and to disconnect the output switch of the train of generators.

5. The control rod power supply system demagnetization protection system according to claim 3, characterized in that: The second control subunit includes a logic AND gate, and a first input end of the logic AND gate inputs a first signal, a second input end of the logic AND gate inputs a second signal, a third input end of the logic AND gate inputs a third signal, and an output end of the logic AND gate outputs a switch control signal, and the switch control signal is used to control the output switch of this column of generators, wherein the first signal is high when the output voltage of this column of generators is greater than a first preset value, and is low otherwise; the second signal is high when the reactive power of this column of generators is greater than a second preset value, and is low otherwise; the third signal is high when the reactive power of another column of generators is less than a third preset value, and is low otherwise.

6. A control rod power system demagnetization protection system, comprising a processor, characterized in that: When executing the stored computer program, the processor implements the steps of the demagnetization protection method according to any one of claims 1 to 2.

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