A generator differential protection method for a rod-controlled power supply system in a nuclear power plant

Abstract

This application belongs to the field of generator relay protection, and specifically discloses a generator differential protection method for a rod-controlled power supply system in a nuclear power plant. The method includes: obtaining the ratio braking characteristic differential protection action criterion, the dual-generator internal short-circuit fault main protection mode, and the current phasors at the neutral point and the machine end of each phase stator winding of each generator; using the current values ​​at the neutral point and the machine end of the corresponding phase stator winding of the dual generator, and according to the dual-generator internal short-circuit fault protection mode, calculating the differential current and braking current of each phase; for each phase stator winding, using the phase differential current, braking current, and ratio braking characteristic differential protection action criterion to determine whether the phase stator winding has a fault; for a faulty stator winding, using the negative sequence power direction criterion of the phase stator winding to determine the generator to which the fault belongs. This application can effectively identify inter-turn short circuits, inter-phase short circuits, and stator welding faults in rod-controlled power supply generators, and determine the faulty unit.

Description

Technical Field

[0001] The present application belongs to the field of generator relay protection, and more specifically, relates to a generator differential protection method for a rod-controlled power supply system of a nuclear power plant. Background Art

[0002] In nuclear power plants, the reactor rod control system (RCS) drives the lifting and insertion of fuel rods, achieving reactor power regulation. The RCPS is a dedicated electrical system that powers the control rod drive mechanism (CRDM). The core power generation unit consists of two generators operating in parallel. Internal short-circuit faults in the generator stator windings include phase-to-phase short-circuit faults, branch-to-branch short-circuit faults, and turn-to-turn short-circuit faults. Short-circuit faults can cause large short-circuit currents, causing serious damage to the generator. Main protection for internal generator faults includes generator longitudinal differential protection, split-phase transverse differential protection, and single-element transverse differential protection. Unlike conventional generators that operate in parallel only at the generator end, the generators in a RCPS system are connected at the generator end and the neutral point. This creates a closer connection between the two generators, and the fault characteristics differ from those of traditional parallel generators. Therefore, the optimal configuration of main protection involves selecting the appropriate protection type to fully address different faults.

[0003] Scholars have analyzed examples of main protection configurations for generators with different winding forms, and proposed that different optimization design schemes should be adopted for different generator winding structures. Longitudinal current differential protection mainly responds to phase-to-phase short-circuit faults, while for branch-to-branch short-circuit faults and turn-to-turn short-circuit faults, if the number of terminals led out on the neutral point side is sufficient, incomplete longitudinal differential protection and transverse differential protection schemes are adopted, and the protection sensitivity is relatively high. However, some generators have only one lead-out terminal per phase on the neutral point side, making it difficult to configure incomplete longitudinal differential protection and transverse differential protection. For branch-to-branch short-circuit faults and turn-to-turn short-circuit faults, negative-sequence power direction protection, longitudinal fundamental zero-sequence voltage protection, and rotor second harmonic current protection may be configured. For longitudinal differential protection and split-phase transverse differential protection, relevant research and applications are relatively complete, and current research is mostly focused on other auxiliary criteria.

[0004] Because the differential protection for the generators in the control rod drive mechanism power system is limited by the configuration of the protection CTs (current transformers), it can only respond to phase-to-phase short-circuit faults in the stator windings and lacks the ability to detect inter-turn faults or inter-branch faults that may occur in the stator windings. Furthermore, the existing fixed-threshold differential protection for short-circuit faults is prone to misoperation and failure. Summary of the Invention

[0005] In response to the defects of the existing technology, the purpose of this application is to provide a generator differential protection method for the rod-controlled power supply system of a nuclear power plant, aiming to solve the problem that the existing differential protection cannot identify internal faults of the stator winding and provide protection due to the use of a single-branch stator winding in the rod-controlled power supply generator.

[0006] To achieve the above objectives, in a first aspect, the present application provides a generator differential protection method for a rod-controlled power supply system in a nuclear power plant, wherein the generators of the rod-controlled power supply system operate in a dual-machine parallel operation condition, and the dual-machine joint differential protection adopts a ratio-restraint characteristic differential protection. The differential protection method comprises:

[0007] S1. Obtain the ratio braking characteristic differential protection action criteria, obtain the dual generator internal short-circuit fault main protection mode and the current value at the neutral point and the generator terminal of each phase of the stator winding of each generator;

[0008] S2. Integrate the dual-generator information and use the current values ​​at the neutral point and generator terminals of the corresponding phases of the stator windings of the dual generators. Calculate the differential current and braking current for each phase based on the dual generator internal short-circuit fault protection method.

[0009] S3. For each phase of the stator winding, the dual-machine differential current, dual-machine braking current and ratio braking characteristic differential protection action criteria of the phase are used to determine whether the stator winding of the phase is faulty;

[0010] S4. For each phase stator winding that has a fault, determine the generator that has a fault using the negative sequence power direction criterion of the phase stator winding.

[0011] Preferably, the ratio braking characteristic differential protection action criterion is:

[0012] When I res ≤I res.0 hour,

[0013]

[0014] When I res >I res.0 hour,

[0015]

[0016] Among them, I op is the differential current, I res is the braking current, I op.0 is the minimum operating current of the differential protection, which is set by measuring the unbalanced current between the two generators; I res.0 is the minimum braking current of the differential protection, which is used to provide braking effect when an external short circuit occurs in the generator; m is the slope of the protection action characteristic.

[0017] Preferably, the main protection mode for the internal short circuit fault of the dual generators is to use only incomplete longitudinal differential protection, only split-phase transverse differential protection, or both incomplete longitudinal differential protection and split-phase transverse differential protection.

[0018] Preferably, when the main protection mode for the internal short-circuit fault of the dual generators is incomplete longitudinal differential protection, the current information of the two generators is integrated and the differential current and braking current of each phase are calculated using the current of the two generators:

[0019] The differential current I of phase A op.A =|2I2-I1-I3|;

[0020] Braking current I of phase A res.A =|(2I2+I1+I3) / 4|;

[0021] The differential current I of phase B op.B =|2I6-I5-I7|;

[0022] Braking current I of phase B res.B =|(2I6+I5+I7) / 4|;

[0023] The differential current I of phase C op.C =|2I 10 -I9-I 11 |;

[0024] Braking current I of phase C res.C =|(2I 10 +I9+I 11 ) / 4|;

[0025] Among them, I1, I5, I9 are the current phasors at the neutral point of the A, B, and C phase stator windings of the first generator, respectively. I3, I7, I 11 are the current phasors at the neutral point of the A, B, and C phase stator windings of the second generator, I2, I6, and I 10 are the current phasors of the A, B, and C phase stator windings at the machine ends of the first generator, respectively, and || represents the amplitude.

[0026] Preferably, when the main protection mode for the internal short-circuit fault of the dual generators is split-phase differential protection, the current information of the two generators is integrated and the current of the two generators is used to calculate the differential current and braking current of each phase:

[0027] The differential current I of phase A op.A =|I1-I3|;

[0028] Braking current I of phase A res.A =|(I1+I3) / 2|;

[0029] The differential current I of phase Bop.B =|I5-I7|;

[0030] Braking current I of phase B res.B =|(I5+I7) / 2|;

[0031] The differential current I of phase C op.C =|I9-I 11 |;

[0032] Braking current I of phase C res.C =|(I9+I 11 ) / 2|;

[0033] Among them, I1, I5, I9 are the current phasors of the A, B, and C phase stator windings at the neutral point of the first generator, I3, I7, I 11 are the current phasors at the neutral point of the A, B, and C phase stator windings of the second generator, respectively, and || represents the amplitude.

[0034] Preferably, the main protection mode for internal short-circuit fault of the dual generators adopts incomplete longitudinal differential protection and split-phase transverse differential protection at the same time. When and only when both protection modes are judged to be in the braking area, it is determined that the stator winding of this phase has not failed. Otherwise, it is determined that the stator winding of this phase has failed.

[0035] Preferably, the generator causing the fault is determined using the negative sequence power direction criterion of the phase stator winding as follows:

[0036] like If , it is a faulty generator, otherwise, it is a normal generator; is the phase angle of ΔU2, ΔU2 is the phasor difference of the negative sequence voltage before and after the fault, is the phase angle of ΔI2, ΔI2 is the phase difference of the negative sequence current before and after the fault, It is the sensitivity angle of the negative sequence power directional relay.

[0037] Preferably, if no fault occurs in any of the three-phase stator windings, the current value at the neutral point and the machine end of each phase stator winding of each generator is re-obtained, and S2-S4 are executed again.

[0038] Preferably, the method further comprises:

[0039] When a fault is detected and the faulty generator is identified, the faulty generator is shut down and removed from the current system protection mode.

[0040] To achieve the above objectives, in a second aspect, the present application provides a computer-readable storage medium, which stores computer instructions. When a computer reads the computer instructions in the storage medium, the computer executes the differential protection method as described in the first aspect.

[0041] It can be understood that the beneficial effects of the second aspect can be found in the relevant description of the first aspect above, and will not be repeated here.

[0042] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies:

[0043] This application proposes a generator differential protection method for a nuclear power plant's rod-controlled power supply system, comprising the following steps: S1. Obtaining a ratio-restraint differential protection action criterion, obtaining the primary protection mode for a dual-generator internal short-circuit fault, and the current values ​​at the neutral point and generator terminals of each phase's stator winding for each generator; S2. Integrating dual-generator information, using the current values ​​at the neutral point and generator terminals of the corresponding phase's stator windings, and calculating the differential current and braking current for each phase based on the dual-generator internal short-circuit fault protection mode; S3. For each stator winding phase, using the dual-generator differential current, dual-generator braking current, and the ratio-restraint differential protection action criterion, determining whether a fault has occurred in that phase's stator winding; S4. For each faulty stator winding phase, using the negative-sequence power direction criterion for that phase's stator winding, identifying the generator causing the fault. Generator sets in nuclear power plant rod-controlled power supply systems typically utilize a single-branch connection for each phase's stator winding. However, both the traditional incomplete longitudinal differential protection and transverse differential protection need to extract characteristic quantities on different branches of each phase for protection, so they cannot be applied in the protection of the generator set of the rod-controlled power supply system. However, the rod-controlled power supply generator is in a dual-machine parallel state under normal operating conditions, and the neutral points and machine ends of the two generators are connected in parallel. The stator winding of each phase can be equivalent to a dual-branch connection structure. Based on this characteristic, the present application proposes a joint differential protection method for dual-machine parallel operation, and at the same time extracts the characteristic quantities of the stator windings of the two motors to construct a criterion, fuses the information of the two machines, identifies the inter-turn short circuit, inter-phase short circuit, and stator welding faults of the rod-controlled power supply generator, determines the faulty unit, and implements protection. It can solve the problem that the existing differential protection of the rod-controlled power supply generator cannot effectively identify the internal faults of the stator winding and perform protection due to the use of a single-branch stator winding. It can meet the needs of actual projects and is of great significance to ensuring the safe and stable operation of the rod-controlled power supply generator set. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This application provides a flow chart of a generator differential protection method for a nuclear power plant rod-controlled power system.

[0045] Figure 2 Schematic diagram of the ratio differential protection action characteristics provided in an embodiment of the present application.

[0046] Figure 3 This is a schematic diagram of the overall structure of the nuclear power plant rod-controlled power generator system provided in an embodiment of the present application.

[0047] Figure 4 Schematic diagram of the construction method of the incomplete longitudinal differential current of two machines and the split-phase transverse differential current of two machines provided in the embodiments of the present application.

[0048] Figure 5 This is the main wiring diagram of the equipment for implementing the dynamic mold experiment provided in the embodiment of the present application.

[0049] Figure 6 This is a waveform diagram of different protection action currents and braking currents under the generator stator winding inter-turn short-circuit fault condition provided in the embodiment of the present application.

[0050] Figure 7 This is a waveform diagram of different protection action currents and braking currents under the generator stator winding phase-to-phase short-circuit fault condition provided in the embodiment of the present application.

[0051] Figure 8 This is the phase angle difference between the negative-sequence voltage and the negative-sequence current after a stator winding fault provided in an embodiment of the present application.

[0052] Figure 9 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0054] The term "and / or" as used herein describes an association between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. The symbol " / " as used herein indicates that the related objects are in an "or" relationship, for example, A / B means either A or B.

[0055] The terms "first" and "second" in this specification and claims are used to distinguish different objects rather than to describe a specific order of objects. For example, "first response message" and "second response message" are used to distinguish different response messages rather than to describe a specific order of response messages.

[0056] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0057] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more, for example, multiple processing units means two or more processing units, etc.; multiple elements means two or more elements, etc.

[0058] Next, the technical solutions provided in the embodiments of this application are introduced.

[0059] like Figure 1 As shown, the present application provides a generator differential protection method for a rod-controlled power supply system of a nuclear power plant, wherein the generator of the rod-controlled power supply system operates in a dual-machine parallel operation condition, and the dual-machine joint differential protection adopts a ratio braking characteristic differential protection. The differential protection method includes:

[0060] S1. Obtain the ratio braking characteristic differential protection action criterion, obtain the main protection mode for the internal short-circuit fault of the dual generators, and the current value at the neutral point and the machine end of each phase of the stator winding of each generator.

[0061] Preferably, if Figure 2 As shown in FIG, the ratio braking characteristic differential protection action criterion is:

[0062] When I res ≤I res.0 hour,

[0063]

[0064] When I res >I res.0 hour,

[0065]

[0066] Among them, I op is the differential current, I res is the braking current, I op.0 The minimum operating current of the differential protection is set by measuring the unbalanced current between the two generators. It is necessary to avoid the differential current caused by the unbalanced power distribution between the two generators and the inconsistency of the generator parameters. Generally, the fundamental current value of the generator terminal under the maximum load condition is taken. For this unit, the value is 40A. res.0 It is the minimum braking current of the differential protection, which is used to show the braking effect when an external short circuit occurs. Theoretically, braking is only required when the short-circuit current is greater than the rated current. Generally, the fundamental current value of the generator end under the maximum load condition is taken. The value of this unit is 40A; m is the slope of the protection action characteristic, which is set to 0.5 based on engineering experience.

[0067] Preferably, the main protection mode for the internal short circuit fault of the dual generators is to use only incomplete longitudinal differential protection, only split-phase transverse differential protection, or both incomplete longitudinal differential protection and split-phase transverse differential protection.

[0068] S2. Integrate the dual-machine information and use the current values ​​at the neutral point and the machine end of the stator winding of the corresponding phase of the dual generators. According to the internal short-circuit fault protection mode of the dual generators, calculate the differential current and braking current of each phase.

[0069] The rod-controlled power system operates in a dual-generator parallel configuration, with the neutral points of both generators connected in parallel to the generator terminals. For example, the current parameter obtained at the neutral point of phase A of one generator's stator is I1, and the current parameter obtained at the generator terminal is I2. The current parameter obtained at the neutral point of the corresponding phase of the other generator's stator is I3.

[0070] Preferably, when the main protection mode for the internal short-circuit fault of the dual generators is incomplete longitudinal differential protection, the current information of the two generators is integrated and the differential current and braking current of each phase are calculated using the current of the two generators:

[0071] The differential current I of phase A op.A =|2I2-I1-I3|;

[0072] Braking current I of phase A res.A =|(2I2+I1+I3) / 4|;

[0073] The differential current I of phase B op.B =|2I6-I5-I7|;

[0074] Braking current I of phase B res.B =|(2I6+I5+I7) / 4|;

[0075] The differential current I of phase C op.C =|2I 10 -I9-I 11 |;

[0076] Braking current I of phase C res.C =|(2I 10 +I9+I 11 ) / 4|;

[0077] Among them, I1, I5, I9 are the current phasors at the neutral point of the A, B, and C phase stator windings of the first generator, respectively. I3, I7, I 11 are the current phasors at the neutral point of the A, B, and C phase stator windings of the second generator, I2, I6, and I 10 are the current phasors of the A, B, and C phase stator windings at the machine ends of the first generator, respectively, and || represents the amplitude.

[0078] Preferably, when the main protection mode for the internal short-circuit fault of the dual generators is split-phase differential protection, the current information of the two generators is integrated and the current of the two generators is used to calculate the differential current and braking current of each phase:

[0079] The differential current I of phase A op.A =|I1-I3|;

[0080] Braking current I of phase A res.A =|(I1+I3) / 2|;

[0081] The differential current I of phase B op.B =|I5-I7|;

[0082] Braking current I of phase B res.B =|(I5+I7) / 2|;

[0083] The differential current I of phase C op.C =|I9-I 11 |;

[0084] Braking current I of phase C res.C =|(I9+I 11 ) / 2|;

[0085] Among them, I1, I5, I9 are the current phasors of the A, B, and C phase stator windings at the neutral point of the first generator, I3, I7, I 11 are the current phasors at the neutral point of the A, B, and C phase stator windings of the second generator, respectively, and || represents the amplitude.

[0086] S3. For each phase of the stator winding, the dual-machine differential current, dual-machine braking current and ratio braking characteristic differential protection action criterion of the phase are used simultaneously to determine whether the stator winding of the phase is faulty.

[0087] If the primary protection for a dual-generator internal short-circuit fault utilizes only incomplete longitudinal differential protection or only split-phase transverse differential protection, the result is determined to be in the protection braking zone, and the stator winding of that phase is deemed to be operating normally. For dual-generator internal short-circuit faults, the primary protection utilizes both incomplete longitudinal differential protection and split-phase transverse differential protection. The incomplete longitudinal differential protection criteria and the split-phase transverse differential protection criteria of the dual-generator combined differential protection are independently used for judgment, and both current groups utilize the same ratio braking characteristics. The two judgment methods are OR-gate related; if one of the judgment criteria indicates a fault, the system is deemed to have failed.

[0088] Preferably, the primary protection for internal short-circuit faults in the dual generators utilizes both incomplete longitudinal differential protection and split-phase transverse differential protection. If and only if both protection modes indicate a braking zone, the stator winding for that phase is considered fault-free. Otherwise, the stator winding for that phase is considered faulty. This dual differential protection mechanism further ensures protection reliability.

[0089] S4. For each phase stator winding that has a fault, determine the generator that has a fault using the negative sequence power direction criterion of the phase stator winding.

[0090] A fault inside a generator is equivalent to a negative-sequence power supply inside the stator winding. Utilizing this characteristic, the present application distinguishes faulty generators from healthy ones by the direction of the negative-sequence power flow.

[0091] Preferably, the generator causing the fault is determined using the negative sequence power direction criterion of the phase stator winding as follows:

[0092] like It indicates that the phase angle of the fault component negative sequence voltage ΔU2 of the fault unit should lead the fault component negative sequence current ΔI2 by a certain angle, then it is a faulty generator, otherwise, it is a non-faulty generator; where, is the phase angle of ΔU2, ΔU2 is the phasor difference of the negative sequence voltage before and after the fault, is the phase angle of ΔI2, ΔI2 is the phase difference of the negative sequence current before and after the fault, is the sensitive angle of the negative sequence power directional relay, which is generally 70° to 80° in engineering, and 75° in this embodiment.

[0093] Preferably, if no fault occurs in any of the three-phase stator windings, the current value at the neutral point and the machine end of each phase stator winding of each generator is re-obtained, and S2-S4 are executed again.

[0094] Preferably, the method further comprises:

[0095] When a fault is detected and the faulty generator is identified, the faulty generator is shut down and removed from the current system protection mode.

[0096] It should be noted that this application does not need to distinguish between stator turn-to-turn faults, phase-to-phase faults, and open welding faults. When a fault is determined to have occurred and the faulty generator is classified, the faulty generator is directly shut down to cut off the protection mode of the current system.

[0097] Example

[0098] The overall structure of the nuclear power plant rod-controlled power generator system in this embodiment is as follows: Figure 3As shown, the control rod drive power generator includes two parallel three-phase four-wire generators, and a half-wave rectifier circuit is used on the load side to supply power to multiple groups of control rods.

[0099] Because the rod-controlled power generator set has a single-branch winding, it cannot be equipped with incomplete longitudinal differential protection and transverse differential protection. However, under normal operating conditions, the rod-controlled power generator operates in a dual-machine parallel condition, with the two generators connected in parallel at the neutral point and the machine ends. This is exactly the same as installing current transformers on the two branches of a generator. It can be roughly regarded as a single generator. In this case, protection CTs are configured on both "branches" of the generator, which can achieve similar incomplete longitudinal differential protection and split-phase transverse differential protection.

[0100] like Figure 4 As shown in the figure, in this implementation, the main protection mode for the internal short circuit fault of the dual generators adopts both incomplete longitudinal differential protection and split-phase transverse differential protection. I1, I5, I9 are the current phasors at the neutral point of the A, B, and C phase stator windings of generator No. 1, respectively. I3, I7, I 11 are the current phasors at the neutral point of the stator winding of phases A, B, and C of generator No. 2, I2, I6, I 10 They are the current phasors at the machine ends of the A, B, and C phase stator windings of generator No. 1 respectively.

[0101] Figure 5 To implement the main wiring diagram of the dynamic mold test equipment, dynamic mold units 2 and 10, with identical parameters, were operated in parallel. The two dynamic mold generators had a capacity of 7.5 kVA, a rated voltage of 220 V, and a rated current of 20 A. This prevented any impact on the fault characteristics. The 220 V bus was connected to a programmable AC load, which simulated the load of a half-wave rectified CRDM coil. Voltage and current transformers were installed at the generator neutral point and generator terminals to measure the required electrical quantities.

[0102] Figure 6 The waveforms of different protection operating currents and braking currents under the condition of inter-turn short circuit fault of generator stator winding are shown. The operating currents of dual-machine split phase differential protection and dual-machine incomplete longitudinal differential protection are higher than the operating current threshold value I after the inter-turn short circuit fault occurs. op.0 , the braking current is lower than or equal to the braking current threshold value I res.0 , the protection can operate correctly, so the dual-machine split-phase differential protection and the dual-machine incomplete longitudinal differential protection can both operate correctly on turn-to-turn short-circuit faults.

[0103] Figure 7 Waveforms of different protection operating currents and braking currents under the condition of interphase short circuit fault of generator stator winding; after the interphase short circuit fault occurs, the operating current of the dual-machine split phase differential protection is higher than the operating current threshold value I op.0 , the braking current is lower than or equal to the braking current threshold value Ires.0 , the protection can operate correctly. However, the operating current and braking current of the dual-machine incomplete longitudinal differential protection are much larger than the corresponding threshold values. Figure 5 From the corresponding ratio braking protection characteristics, it can be seen that at this time they are both in the corresponding protection action area, so both the single-machine complete longitudinal differential protection and the dual-machine incomplete longitudinal differential protection can operate correctly, and both protection types can operate correctly on phase-to-phase short-circuit faults.

[0104] Figure 8 The phase angle difference between the negative sequence voltage and negative sequence current after the stator winding fault is calculated for the inter-turn short circuit fault and the phase short circuit fault condition of the stator winding. The negative sequence current and negative sequence voltage at the machine end before and after the fault are calculated respectively. The negative sequence current and negative sequence voltage at the machine end are very small before the fault occurs. After the fault occurs, there are obvious negative sequence current and voltage components under different fault conditions. The phase characteristics can be extracted according to the voltage. The phase difference between the negative sequence voltage and negative sequence current after the fault is as follows: Figure 8 As shown, Generator 2, as the faulty generator, has a phase angle difference of approximately 70° between its terminal negative-sequence voltage and negative-sequence current, satisfying the faulty generator criterion in S4. Generator 10, on the other hand, as the normally operating generator, has a phase angle difference of approximately -110° between its terminal negative-sequence voltage and negative-sequence current, preventing it from being misidentified as a faulty generator. Table 1 shows the phase angle difference between negative-sequence voltage and negative-sequence current under different fault scenarios.

[0105] Table 1

[0106]

[0107] As can be seen from the above table, the negative-sequence power direction criterion can correctly identify faulty units and non-faulty units in different fault scenarios, thus achieving the selectivity requirements of protection.

[0108] It is understandable that the detailed functional implementation of each of the above units / modules can be found in the introduction of the aforementioned method embodiment, and will not be repeated here.

[0109] It should be understood that the above-mentioned device is used to execute the method in the above-mentioned embodiment. The implementation principle and technical effect of the corresponding program module in the device are similar to those described in the above-mentioned method. The working process of the device can refer to the corresponding process in the above-mentioned method and will not be repeated here.

[0110] Based on the method in the above embodiment, the embodiment of the present application provides an electronic device, such as Figure 9As shown, the electronic device may include: a processor, a communications interface, a memory, and a communications bus, wherein the processor, the communications interface, and the memory communicate with each other via the communications bus. The processor may call logic instructions in the memory to execute the method of the above embodiment.

[0111] In addition, the logical instructions in the above-mentioned memory can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application.

[0112] Based on the method in the above embodiment, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method in the above embodiment.

[0113] Based on the method in the above embodiment, an embodiment of the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method in the above embodiment.

[0114] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0115] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC.

[0116] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted via the computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid state drive (SSD)).

[0117] It will be understood that the various numerical numbers involved in the embodiments of the present application are merely distinctions for the convenience of description and are not intended to limit the scope of the embodiments of the present application.

[0118] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A generator differential protection method for a rod-controlled power supply system in a nuclear power plant, characterized in that: The generator of the rod-controlled power supply system operates in a dual-machine parallel operation condition, and the dual-machine joint differential protection adopts ratio braking characteristic differential protection. The differential protection method includes: S1. Obtaining the ratio-restraint characteristic differential protection action criteria, obtaining the dual-generator internal short-circuit fault main protection mode and the current values ​​at the neutral point and at the generator terminal of each phase stator winding of each generator, wherein the dual-generator internal short-circuit fault main protection mode is to use only incomplete longitudinal differential protection, only split-phase transverse differential protection, or both incomplete longitudinal differential protection and split-phase transverse differential protection; S2. Integrate the dual-generator information and use the current values ​​at the neutral point and generator terminals of the corresponding phases of the stator windings of the dual generators. Calculate the differential current and braking current for each phase based on the dual-generator internal short-circuit fault primary protection mode. S3. For each phase of the stator winding, the phase differential current, braking current and ratio braking characteristic differential protection action criterion are used to determine whether the phase stator winding is faulty; S4. For each phase stator winding that has a fault, determine the generator that has a fault using the negative sequence power direction criterion of the phase stator winding, as follows: , then it is a faulty generator, otherwise, it is a normal generator; where, for The phase angle, is the phasor difference of the negative sequence voltage at the generator end before and after the fault, for The phase angle, is the phase difference of the negative sequence current before and after the fault, It is the sensitivity angle of the negative sequence power directional relay.

2. The differential protection method according to claim 1, wherein: The ratio braking characteristic differential protection action criterion is: when hour, when hour, in, is the differential current, is the braking current, It is the minimum operating current of the differential protection, which is set by measuring the unbalanced current between the two generators; It is the minimum braking current of the differential protection, used to provide braking effect when the generator has an external short circuit; It is the slope of the protection action characteristic.

3. The differential protection method according to claim 1, wherein: When the main protection mode for dual generator internal short-circuit faults is incomplete longitudinal differential protection, the current information of both generators is integrated and the currents of both generators are used to calculate the differential current and braking current of each phase: Differential current of phase A ; Braking current of phase A ; Differential current of phase B ; Braking current of phase B ; Differential current of phase C ; Braking current of phase C ; in, are the current phasors at the neutral point of the A, B, and C phase stator windings of the first generator, are the current phasors at the neutral point of the A, B, and C phase stator windings of the second generator, are the current phasors of the A, B, and C phase stator windings at the machine ends of the first generator, respectively, and || represents the amplitude.

4. The differential protection method according to claim 1, wherein: When the main protection mode for dual generator internal short-circuit faults is split-phase differential protection, the current information of both generators is integrated and the current of both generators is used to calculate the differential current and braking current of each phase: Differential current of phase A ; Braking current of phase A ; Differential current of phase B ; Braking current of phase B ; Differential current of phase C ; Braking current of phase C ; in, are the current phasors of the A, B, and C phases of the stator at the neutral point of the first generator, are the current phasors at the neutral point of the A, B, and C phase stator windings of the second generator, respectively, and || represents the amplitude.

5. The differential protection method according to claim 1, wherein: The main protection mode for internal short-circuit fault of dual generators adopts incomplete longitudinal differential protection and split-phase transverse differential protection at the same time. If and only if both protection modes are judged to be in the braking area, it is determined that the stator winding of this phase has not failed. Otherwise, it is determined that the stator winding of this phase has failed.

6. The differential protection method according to any one of claims 1 to 5, characterized in that: If no fault occurs in any of the three-phase stator windings, the current values ​​at the neutral point and the machine end of each phase stator winding of each generator are obtained again, and S2-S4 are executed again.

7. The differential protection method according to any one of claims 1 to 5, characterized in that: The method further includes: When a fault is detected and the faulty generator is identified, the faulty generator is shut down and removed from the current system protection mode.

8. A computer-readable storage medium, characterized in that The storage medium stores computer instructions. When a computer reads the computer instructions in the storage medium, the computer executes the differential protection method according to any one of claims 1 to 7.

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