Generator field loss judgment method, device and electronic equipment

Abstract

The present invention discloses a method for judging the loss of excitation of a generator in a power supply system of a control rod drive mechanism, including: collecting the excitation current, the three-phase voltage at the generator terminal, and the three-phase current at the generator terminal; calculating the excitation current value, the effective value of the positive-sequence voltage at the generator terminal, the sudden drop amount of the positive-sequence voltage at the generator terminal, and the reactive power; in response to the simultaneous satisfaction of three conditions: the reduction of the excitation current value, the sudden drop of the positive-sequence voltage at the generator terminal, and the reverse of the reactive power, it is determined that a loss-of-excitation fault occurs in the excitation circuit of the generator in the power supply system of the control rod drive mechanism. The solution of the present invention can quickly identify the excitation circuit fault, and the time-delay setting value of the loss-of-excitation protection does not need to be coordinated with other protections, and only needs to be set according to a short delay, solving the problem of overstepping tripping caused by the excitation circuit fault of the generator in the power supply system of the control rod drive mechanism.

Description

Technical Field

[0001] The present invention belongs to the field of relay protection of power systems, and particularly relates to a method, device and electronic equipment for judging the loss of excitation of a generator in a power supply system of a control rod drive mechanism. Background Art

[0002] The power supply system (RAM) of the control rod drive mechanism of a nuclear power plant is used to supply power to the reactor control rod drive mechanism. It passes through the emergency shutdown circuit breaker of the reactor protection system, and after rectification and regulation by the reactor rod control system, it provides power to the reactor control rod drive mechanism. RAM consists of two motor-generator sets with inertial flywheels, an excitation regulating mechanism, a motor power supply line, a generator output line, and related electrical protections. The two asynchronous motors driving the generator are powered by 380V busbars of different systems. Power is supplied to the control rod drive mechanism through the outgoing line circuit breaker and the shutdown circuit breaker. When the entire RAM system fails and shuts down, the power coils of the control drive mechanism lose power. This will cause the control rod to quickly drop under the action of gravity, resulting in reactor shutdown, with serious consequences. Therefore, the reliability requirements for the generator protection of the RAM system are high. At present, most of the RAM generator protections still use traditional relays, and very few use imported RAM protection devices, resulting in problems such as imperfect protection principles and improper coordination of different protections. In particular, the loss of excitation protection principle is simply designed. Different from conventional generator sets, the loss of excitation protection based on impedance principle is no longer applicable to RAM generators. Currently, only excitation overcurrent is used for discrimination, which is difficult to cope with complex faults and has too long setting delays. As a result, it cannot be effectively coordinated with the backup protection of RAM generators. When a fault occurs in the excitation circuit, it is very likely to cause overstepping tripping, expanding the power outage range and bringing potential safety hazards to the safe operation of nuclear power plants. Summary of the Invention

[0003] The main purpose of the present invention is to provide a method for judging the loss of excitation of a generator in a power supply system of a control rod drive mechanism, so as to solve the problems that the existing loss of excitation protection is difficult to cope with complex faults and has too long setting delays, resulting in ineffective coordination with the backup protection of RAM generators and very likely causing overstepping tripping when a fault occurs in the excitation circuit. This application also provides a corresponding device and electronic equipment for judging the loss of excitation of the generator at the same time.

[0004] To achieve the above object, the solution of the present invention is:

[0005] According to the first aspect of the present application, a method for judging the loss of excitation of a generator in a power supply system of a control rod drive mechanism is provided, including:

[0006] Collect the excitation current, the three-phase voltage at the generator terminal, and the three-phase current at the generator terminal;

[0007] Calculate the excitation current value, the effective value of the positive-sequence voltage at the generator terminal, the sudden drop amount of the positive-sequence voltage at the generator terminal, and the reactive power;

[0008] When the three conditions of a decrease in the excitation current value, a sudden drop in the positive-sequence voltage at the machine terminal, and a reverse reactive power are simultaneously satisfied, it is determined that a field loss fault has occurred in the generator excitation circuit of the control rod drive mechanism power supply system.

[0009] Preferably, when the generator of the control rod drive mechanism power supply system is of brushless excitation type, the excitation current is the exciter excitation current; when the generator of the control rod drive mechanism power supply system is of phase compound excitation type, the excitation current is the generator excitation current.

[0010] Preferably, the determination condition for the decrease in the excitation current value is that the excitation current value is lower than the excitation current setting value.

[0011] Preferably, the excitation current setting value is set to avoid the excitation current under the no-load condition of the generator of the control rod drive mechanism power supply system.

[0012] Preferably, when the criterion of formula (1) is satisfied, it is determined that the excitation current value has decreased:

[0013]

[0014] wherein, I F is the excitation current value; I F.set is the excitation current setting value; k1 is a reliability coefficient, taking a value of 0.5 - 0.8; I F.d0 is the excitation current under the no-load condition of the generator of the control rod drive mechanism power supply system.

[0015] Preferably, the determination condition for the reverse reactive power is that the reactive power is lower than the reverse reactive power setting value.

[0016] Preferably, when the criterion of formula (2) is satisfied, it is determined that the reactive power is reversed:

[0017]

[0018] wherein, Q fdj is the reactive power of the generator of the control rod drive mechanism power supply system; Q set is the reverse reactive power setting value; k2 is a reliability coefficient, taking a value of 5% - 10%; Q n is the rated reactive power of the generator of the control rod drive mechanism power supply system.

[0019] Preferably, the determination condition for the sudden drop in the positive-sequence voltage at the machine terminal is that the sudden drop amount of the positive-sequence voltage at the machine terminal is higher than the positive-sequence voltage sudden drop setting value.

[0020] Preferably, when the criterion of formula (3) is satisfied, it is determined that there is a sudden drop in the positive-sequence voltage at the machine terminal:

[0021]

[0022] Wherein: Δt is the data window duration; U f1 [t] is the effective value of the positive-sequence voltage of the generator terminal of the control rod drive mechanism power supply system at time t; U f1 [t + Δt] is the effective value of the positive-sequence voltage of the generator terminal of the control rod drive mechanism power supply system at time t+Δt; ΔU f1 is the actual sudden drop in the positive-sequence voltage of the generator terminal of the control rod drive mechanism power supply system; ΔU f1.set is the set value of the sudden drop in the positive-sequence voltage of the generator terminal of the control rod drive mechanism power supply system.

[0023] Preferably, if the criterion of formula (3) is satisfied, it is determined as a sudden drop in the positive-sequence voltage of the generator terminal after the first time delay; if the criterion of formula (3) is no longer satisfied, it is determined that the sudden drop in the positive-sequence voltage of the generator terminal is not satisfied after the second time delay.

[0024] According to the second aspect of the present application, a device for judging the loss of excitation of a generator of a control rod drive mechanism power supply system is provided, including a collection unit, a calculation unit, and a loss-of-excitation fault determination unit, wherein:

[0025] The collection unit is used to collect the excitation current, the three-phase voltage at the generator terminal, and the three-phase current at the generator terminal;

[0026] The calculation unit is used to calculate the excitation current value, the effective value of the positive-sequence voltage of the generator terminal, the sudden drop amount of the positive-sequence voltage of the generator terminal, and the reactive power;

[0027] The loss-of-excitation fault determination unit is used to determine that a loss-of-excitation fault has occurred in the excitation circuit of the generator of the control rod drive mechanism power supply system when the three conditions of a decrease in the excitation current value, a sudden drop in the positive-sequence voltage of the generator terminal, and a reverse of the reactive power are simultaneously satisfied.

[0028] According to the third aspect of the present application, an electronic device for judging the loss of excitation of a generator of a control rod drive mechanism power supply system is provided, including:

[0029] One or more processors;

[0030] A storage device for storing one or more programs;

[0031] When the one or more programs are executed by the one or more processors, the one or more processors implement the method described in the first aspect.

[0032] The beneficial effects of the present invention are: a new RAM generator loss-of-excitation protection is realized, which can quickly identify faults in the excitation circuit, greatly improve the sensitivity of detecting faults in the excitation circuit, and at the same time, the delay setting value does not need to cooperate with other protections, and only needs to be set according to a short delay, thus avoiding the possibility of overstepping tripping due to improper grading cooperation during excitation circuit faults, and better ensuring the safe operation of nuclear power plants. Description of the Drawings

[0033] Figure 1 The figure shows a flowchart of an embodiment of a method for judging the loss of excitation of a generator in a power supply system of a control rod drive mechanism provided by the present application.

[0034] Figure 2 The figure shows a schematic diagram of the measurement of electrical quantities of a generator in a power supply system (RAM) of a control rod drive mechanism. Among them: IB is an excitation current transmitter of the exciter, TV is a generator terminal voltage transformer of the RAM generator, TA is a current transformer for power calculation of the RAM generator, 40G is the loss-of-excitation protection of the RAM generator, and F is the fault location of the excitation circuit.

[0035] Figure 3 The figure shows a logic block diagram of the present application. Among them: a is the excitation current criterion, b is the reactive power reverse criterion, c is the positive-sequence voltage sudden drop criterion, d is the delay start / return logic, e is the "AND gate" logic, f is the delay action logic, and g is the action output.

[0036] Figure 4 The figure shows a schematic diagram of an embodiment of a device for judging the loss of excitation of a generator in a power supply system of a control rod drive mechanism. Detailed implementation manners

[0037] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present application.

[0038] The present application provides an embodiment of a method for judging the loss of excitation of a generator in a power supply system of a control rod drive mechanism. According to the Figure 1 schematic diagram, the following steps are included:

[0039] S100: Collect the excitation current, the three-phase voltage at the generator terminal, and the three-phase current at the generator terminal.

[0040] Figure 2 It is a schematic diagram of the measurement of electrical quantities of a generator in a power supply system (RAM) of a control rod drive mechanism. IB is an excitation current transmitter of the exciter for collecting the excitation current, TV is a generator terminal voltage transformer of the RAM generator for collecting the three-phase voltage at the generator terminal, and TA is a current transformer for power calculation of the RAM generator for collecting the three-phase current at the generator terminal.

[0041] In some embodiments, when the generator in the power supply system of the control rod drive mechanism is of a brushless excitation mode, the excitation current is the excitation current of the exciter. In some embodiments, when the generator in the power supply system of the control rod drive mechanism is of a phase compound excitation mode, the excitation current is the excitation current of the generator.

[0042] S200: Calculate the excitation current value, the effective value of the positive-sequence voltage at the generator terminal, the sudden drop amount of the positive-sequence voltage at the generator terminal, and the reactive power.

[0043] Calculate the excitation current value based on the collected excitation current. Calculate the effective value of the positive-sequence voltage at the generator terminal based on the collected three-phase voltages at the generator terminal. Calculate the sudden drop amount of the positive-sequence voltage at the generator terminal based on the effective value of the positive-sequence voltage at the generator terminal. Calculate the reactive power based on the collected three-phase voltages and three-phase currents at the generator terminal.

[0044] S300: In response to the simultaneous satisfaction of three conditions: the decrease of the excitation current value, the sudden drop of the positive-sequence voltage at the generator terminal, and the reverse of the reactive power, it is determined that a loss-of-excitation fault occurs in the generator excitation circuit of the control rod drive mechanism power supply system.

[0045] When a fault occurs in the excitation circuit, the excitation current of the control rod drive mechanism power supply system will decrease, the positive-sequence voltage at the generator terminal will decrease, and at the same time, the generator absorbs reactive power, that is, reactive power reverses. Therefore, in this embodiment, the decrease of the excitation current value is used as the main criterion, and the reactive power reverse condition and the sudden drop condition of the positive-sequence voltage at the generator terminal are used as auxiliary criteria to quickly identify the excitation circuit fault. For the RAM generator loss-of-excitation protection delay setting value using this determination method, there is no need to cooperate with other protections, and only short-delay setting is required, and the delay is taken as 0.5 s to 1.0 s.

[0046] Specifically, the determination condition for the decrease of the excitation current value is: the excitation current value is lower than the excitation current setting value. The determination condition for the reverse of the reactive power is: the reactive power is lower than the reactive power reverse setting value. The determination condition for the sudden drop of the positive-sequence voltage at the generator terminal is: the sudden drop amount of the positive-sequence voltage at the generator terminal is higher than the positive-sequence voltage sudden drop setting value.

[0047] In a preferred embodiment, when the criterion of Equation (1) is satisfied, it is determined that the excitation current value decreases:

[0048]

[0049] where, I F is the excitation current value; I F.set is the excitation current setting value; k1 is the reliability coefficient, taking 0.5 to 0.8; I F.d0 is the excitation current of the generator of the control rod drive mechanism power supply system under no-load conditions.

[0050] In a preferred embodiment, when the criterion of Equation (2) is satisfied, it is determined that the reactive power reverses:

[0051]

[0052] where, Q fdj is the reactive power of the generator of the control rod drive mechanism power supply system; Q setis the reactive power reverse setting value; k2 is the reliability coefficient, taking 5% - 10%; Q n is the rated reactive power of the generator of the control rod drive mechanism power supply system.

[0053] In a preferred embodiment, when the criterion of formula (3) is satisfied, it is determined that the positive sequence voltage at the machine terminal suddenly drops:

[0054]

[0055] where: Δt is the data window duration; U f1 [t] is the effective value of the positive sequence voltage at the machine terminal of the generator of the control rod drive mechanism power supply system at time t; U f1 [t + Δt] is the effective value of the positive sequence voltage at the machine terminal of the generator of the control rod drive mechanism power supply system at time t + Δt; ΔU f1 is the actual sudden drop amount of the positive sequence voltage of the generator of the control rod drive mechanism power supply system; ΔU f1.set is the sudden drop setting value of the positive sequence voltage of the generator of the control rod drive mechanism power supply system.

[0056] In a preferred embodiment, if the criterion of formula (3) is satisfied, it is determined that the positive sequence voltage at the machine terminal suddenly drops after the first time delay; if the criterion of formula (3) is no longer satisfied, it is determined that the sudden drop of the positive sequence voltage at the machine terminal is not satisfied after the second time delay.

[0057] The method proposed in this application will be further described below in combination with specific applications. The basic parameters of a certain RAM generator and its excitation system are as follows:

[0058] RAM generator parameters: rated capacity S n is 400 kVA, power factor is 0.25, rated stator voltage U n is 260 V, rated stator current I n is 888 A, and the ratio of the machine terminal voltage transformer is 260 V / 100 V.

[0059] Brushless exciter parameters: rated power P n is 11.8 kW, no-load rated excitation current I F.d0 is 1 A.

[0060] The adopted generator loss-of-excitation judgment method includes:

[0061] Step 1: Collect the excitation current, three-phase voltage at the machine terminal, and three-phase current at the machine terminal.

[0062] Step 2: Calculate the excitation current value, the effective value of the positive sequence voltage at the machine terminal, the sudden drop amount of the positive sequence voltage at the machine terminal, and the reactive power.

[0063] Step 3: Determine that a fault occurs in the excitation circuit of the RAM generator when the excitation current value is lower than the setting value IF.set and the reactive power is lower than the fixed value Q set and the sudden drop amount of the positive-sequence voltage at the machine terminal is higher than the fixed value ΔU f1.set It is determined that a field loss fault has occurred in the generator excitation circuit of the control rod drive mechanism power supply system. The time-delay setting value of the field loss protection of the RAM generator using this determination method does not need to cooperate with other protections and only needs to be set with a short time delay. In this embodiment, the time delay is taken as 0.5 s.

[0064] The criterion for the reduction of the field current value is:

[0065]

[0066] where I F is the field current value of the exciter; I F.set is the field current setting value of the RAM generator field loss protection; k1 is the reliability coefficient, taken as 0.5; I F.d0 is the field current of the RAM generator under no-load conditions.

[0067] When a fault occurs in the excitation circuit, the RAM generator absorbs a large amount of reactive power, and the reactive power is lower than the fixed value Q set , that is, the reactive power reverse condition is satisfied.

[0068] The reactive power reverse criterion is:

[0069]

[0070] where Q fdj is the reactive power of the RAM generator; Q set is the reactive power reverse setting value; k rel is the reliability coefficient, taken as 10%; Q n is the rated reactive power of the RAM generator.

[0071] When a fault occurs in the excitation circuit, the positive-sequence voltage at the machine terminal of the RAM generator decreases, and the sudden drop amount of the positive-sequence voltage at the machine terminal is higher than the fixed value ΔU f1.set , and it is put into operation after a time delay t1; when the sudden drop amount of the positive-sequence voltage at the machine terminal is no longer higher than the fixed value ΔU f1.set after that, it is withdrawn after a time delay t2;

[0072] The sudden drop criterion of the positive-sequence voltage at the machine terminal is:

[0073]

[0074] where: Δt is the data window, taken as 40 ms; U f1 [t] is the effective value of the positive-sequence voltage of the RAM generator at time t; U f1 [t + Δt] is the effective value of the positive-sequence voltage of the RAM generator at time t + Δt; ΔU f1 is the actual sudden drop amount of the positive-sequence voltage of the RAM generator; ΔUf1.set The threshold of the positive-sequence voltage dip at the terminal of the RAM generator is taken as 2.5 V; t1 is taken as 0.2 s; t2 is taken as 10 s.

[0075] Based on the above, the specific protection logic block diagram is as Figure 3 shown. Then, a criterion for the loss-of-excitation protection of the generator in the power supply system of the control rod drive mechanism is:

[0076]

[0077] When the above action equation is satisfied during the operation of the RAM generator, the loss-of-excitation protection operates and trips the outlet circuit breaker of the local RAM generator.

[0078] After adopting the method of the present invention, the faults in the excitation circuit can be quickly identified. The delay setting value does not need to be coordinated with other protections and only needs to be set according to short delay, solving the problem of overstepping tripping caused by the faults in the excitation circuit of the RAM generator.

[0079] Figure 4 This is an embodiment of a device for judging the loss of excitation of a generator in the power supply system of a control rod drive mechanism, including an acquisition unit 1001, a calculation unit 1002, and a loss-of-excitation fault determination unit 1003, where:

[0080] The acquisition unit 1001 is used to acquire the excitation current, the three-phase voltage at the generator terminal, and the three-phase current at the generator terminal. In some embodiments, when the generator in the power supply system of the control rod drive mechanism is of brushless excitation type, the excitation current is the excitation current of the exciter. In some embodiments, when the generator in the power supply system of the control rod drive mechanism is of phase compound excitation type, the excitation current is the excitation current of the generator.

[0081] The calculation unit 1002 is used to calculate the excitation current value, the effective value of the positive-sequence voltage at the generator terminal, the amount of positive-sequence voltage dip at the generator terminal, and the reactive power;

[0082] The loss-of-excitation fault determination unit 1003 is used to determine that a loss-of-excitation fault occurs in the excitation circuit of the generator in the power supply system of the control rod drive mechanism when the three conditions of a decrease in the excitation current value, a positive-sequence voltage dip at the generator terminal, and a reverse of the reactive power are simultaneously satisfied.

[0083] Specifically, the calculation unit 1002 calculates the excitation current value according to the acquired excitation current. The effective value of the positive-sequence voltage at the generator terminal is calculated according to the acquired three-phase voltage at the generator terminal, and the amount of positive-sequence voltage dip at the generator terminal is calculated according to the effective value of the positive-sequence voltage at the generator terminal. The reactive power is calculated according to the acquired three-phase voltage at the generator terminal and the three-phase current at the generator terminal.

[0084] In the loss-of-excitation fault determination unit 1003, the determination condition for a decrease in the excitation current value is that the excitation current value is lower than the excitation current setting value. In a preferred embodiment, when the criterion of formula (1) is satisfied, it is determined that the excitation current value decreases:

[0085]

[0086] Among them, I F is the excitation current value; I F.set is the set value of the excitation current; k1 is the reliability coefficient, taking 0.5 to 0.8; I F.d0 is the excitation current under the no-load condition of the generator of the control rod drive mechanism power supply system.

[0087] In the field loss fault determination unit 1003, the determination condition for the reverse of reactive power is: the reactive power is lower than the reverse reactive power set value. In a preferred embodiment, when the criterion of formula (2) is satisfied, it is determined as reverse reactive power:

[0088]

[0089] Among them, Q fdj is the reactive power of the generator of the control rod drive mechanism power supply system; Q set is the reverse reactive power set value; k2 is the reliability coefficient, taking 5% to 10%; Q n is the rated reactive power of the generator of the control rod drive mechanism power supply system.

[0090] In the field loss fault determination unit 1003, the determination condition for the sudden drop of the positive sequence voltage at the machine terminal is: the sudden drop amount of the positive sequence voltage at the machine terminal is higher than the set value of the sudden drop of the positive sequence voltage. In a preferred embodiment, when the criterion of formula (3) is satisfied, it is determined as the sudden drop of the positive sequence voltage at the machine terminal:

[0091]

[0092] Among them: Δt is the data window duration; U f1 [t] is the effective value of the positive sequence voltage at the machine terminal of the generator of the control rod drive mechanism power supply system at time t; U f1 [t + Δt] is the effective value of the positive sequence voltage at the machine terminal of the generator of the control rod drive mechanism power supply system at time t + Δt; ΔU f1 is the actual sudden drop amount of the positive sequence voltage at the machine terminal of the generator of the control rod drive mechanism power supply system; ΔU f1.set is the set value of the sudden drop of the positive sequence voltage at the machine terminal of the generator of the control rod drive mechanism power supply system.

[0093] In a preferred embodiment, if the criterion of formula (3) is satisfied, it is determined as the sudden drop of the positive sequence voltage at the machine terminal after the first time delay; if the criterion of formula (3) is no longer satisfied, it is determined that the sudden drop of the positive sequence voltage at the machine terminal is not satisfied after the second time delay.

[0094] This application also provides an embodiment of an electronic device for judging the field loss of the generator of the control rod drive mechanism power supply system, including:

[0095] One or more processors;

[0096] A storage device for storing one or more programs;

[0097] When the one or more programs are executed by the one or more processors, the one or more processors implement the method and refinement scheme as Figure 1 shown.

[0098] The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modifications made on the basis of the technical solution according to the technical idea proposed by the present invention fall within the protection scope of the present invention.

Claims

1. A method for judging the loss of excitation of a generator in a power supply system of a control rod drive mechanism, characterized in that, Including: Collecting the excitation current, the three-phase voltage at the generator terminal, and the three-phase current at the generator terminal; Calculating the excitation current value, the effective value of the positive-sequence voltage at the generator terminal, the sudden drop amount of the positive-sequence voltage at the generator terminal, and the reactive power; In response to the simultaneous satisfaction of the three conditions of a decrease in the excitation current value, a sudden drop in the positive-sequence voltage at the generator terminal, and a reverse of the reactive power, it is determined that a field loss fault has occurred in the generator excitation circuit of the control rod drive mechanism power supply system.

2. The method for judging the loss of excitation of the generator in the power supply system of a control rod drive mechanism according to claim 1, wherein: When the generator of the control rod drive mechanism power supply system is of the brushless excitation type, the excitation current is the excitation current of the exciter; when the generator of the control rod drive mechanism power supply system is of the phase compound excitation type, the excitation current is the excitation current of the generator.

3. The method for judging the loss of excitation of the generator in the power supply system of a control rod drive mechanism according to claim 1, wherein: The determination condition for the decrease in the excitation current value is: the excitation current value is lower than the excitation current setting value.

4. The method for judging the loss of excitation of the generator in the power supply system of a control rod drive mechanism according to claim 3, wherein: The excitation current setting value is set according to the excitation current under the no-load condition of the generator of the control rod drive mechanism power supply system.

5. The method for judging the loss of excitation of the generator in the power supply system of a control rod drive mechanism according to claim 3, characterized in that: When the criterion of formula (1) is satisfied, it is determined that the excitation current value has decreased: Among them, I F is the excitation current value; I F.set is the set value of the excitation current; k1 is the reliability coefficient, taking 0.5 to 0.8; I F.d0 is the excitation current of the control rod drive mechanism power supply system under the no-load condition of the generator.

6. The method for judging the loss of excitation of the generator in the power supply system of a control rod drive mechanism according to claim 1, characterized in that: The determination condition for the reverse of the reactive power is: the reactive power is lower than the reactive power reverse setting value.

7. A method for judging the loss of excitation of a generator in a power supply system of a control rod drive mechanism according to claim 6, characterized in that: When the criterion of formula (2) is satisfied, it is determined that the reactive power is reversed: Among them, Q fdj is the reactive power of the generator of the control rod drive mechanism power supply system; Q set is the reactive power reverse setting value; k2 is the reliability coefficient, taking 5% - 10%; Q n is the rated reactive power of the generator of the control rod drive mechanism power supply system.

8. A method for judging the loss of excitation of a generator in a power supply system of a control rod drive mechanism according to claim 1, characterized in that: The determination condition for the sudden drop in the positive-sequence voltage at the generator terminal is: the sudden drop amount of the positive-sequence voltage at the generator terminal is higher than the positive-sequence voltage sudden drop setting value.

9. A method for judging the loss of excitation of a generator in a power supply system of a control rod drive mechanism according to claim 8, characterized in that: When the criterion of formula (3) is satisfied, it is determined that there is a sudden drop in the positive-sequence voltage at the generator terminal: Where: Δt is the data window duration; U f1 [t] is the RMS value of the positive-sequence voltage of the generator terminal of the control rod drive mechanism power supply system at time t; U f1 [t + Δt] is the RMS value of the positive-sequence voltage of the generator terminal of the control rod drive mechanism power supply system at time t + Δt; ΔU f1 is the actual sudden drop in the positive-sequence voltage of the generator terminal of the control rod drive mechanism power supply system; ΔU f1.set is the set value of the sudden drop in the positive-sequence voltage of the generator terminal of the control rod drive mechanism power supply system.

10. A method for judging the loss of excitation of a generator in a power supply system of a control rod drive mechanism as described in claim 9, characterized in that: If the criterion of formula (3) is satisfied, it is determined that there is a sudden drop in the positive-sequence voltage at the generator terminal after a first-time delay; if the criterion of formula (3) is no longer satisfied, it is determined that the sudden drop in the positive-sequence voltage at the generator terminal is not satisfied after a second-time delay.

11. A judging device for the loss of excitation of a generator in a power supply system of a control rod drive mechanism, characterized in that: Including a collection unit, a calculation unit, and a field loss fault determination unit, where: The collection unit is used to collect the excitation current, the three-phase voltage at the generator terminal, and the three-phase current at the generator terminal; The calculation unit is used to calculate the excitation current value, the effective value of the positive-sequence voltage at the generator terminal, the sudden drop amount of the positive-sequence voltage at the generator terminal, and the reactive power; The field loss fault determination unit is used to determine that a field loss fault has occurred in the generator excitation circuit of the control rod drive mechanism power supply system when the three conditions of a decrease in the excitation current value, a sudden drop in the positive-sequence voltage at the generator terminal, and a reverse of the reactive power are simultaneously satisfied.

12. An electronic device for judging the loss of excitation of a generator in a power supply system of a control rod drive mechanism, characterized in that, Including: One or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method according to any one of claims 1-10.

Images