Fault distinguishing method and protection device for generator

Abstract

The invention discloses a fault distinguishing method of a generator and a protection device, and aims to solve the technical problem that it is difficult to accurately distinguish a voltage measurement loop fault and a bus system fault in the prior art. The fault distinguishing method comprises the steps that when it is judged that at least two paths of generator terminal voltage signals have faults, stator current characteristics of a generator are obtained, and whether the fault type is a voltage signal collection fault or a bus fault is judged based on whether a stator current absolute value in the stator current characteristics is abnormal or not. The protection device provided by the invention comprises corresponding function modules for executing the method. By introducing the stator current characteristics for judgment, the fault source can be accurately discriminated, and the protection system misoperation caused by the measurement loop fault is effectively prevented, so that the stability and the safety of the operation of the generator set are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system protection, in particular to a fault distinguishing method of a generator and a protection device. BACKGROUND

[0002] In a power system, a synchronous generator is a core energy conversion device, and the stability of its operation is crucial to the safety of the entire power grid. The excitation system of the generator is responsible for regulating the output voltage of the generator, and the potential transformer (PT) as an important measuring element provides accurate terminal voltage feedback signals for the excitation system. Therefore, the accuracy and reliability of the voltage signal are the basis for ensuring the stable operation of the generator.

[0003] In order to improve the reliability of the system, the related technology usually adopts a configuration mode of double voltage transformers (double PTs) as redundancy. This design aims to obtain accurate voltage data from the other when one of the voltage transformers or its measurement circuit fails, thereby avoiding the loss of control of the entire excitation system due to a single-point measurement failure.

[0004] However, in actual application, the protection logic that relies only on voltage parameters for fault judgment still has several technical defects. First, when part of the voltage transformer circuit fails and the voltage signal is lost, the protection system may mistakenly judge this measurement failure as a serious bus voltage collapse failure, thereby triggering an incorrect forced excitation action, which not only damages the generator equipment but also causes an impact on the stability of the power grid. Second, when both voltage transformer circuits fail, the related technology often lacks effective means to distinguish between the condition of complete failure of the measurement system and the symmetrical or asymmetrical fault of the bus, resulting in the protection system being unable to accurately judge the fault type and thus possibly causing a misoperation. The root cause of the above problems lies in that the related fault diagnosis method mainly relies on single voltage information and fails to fully utilize other physical quantities that can reflect the real operating state of the generator, resulting in insufficient fault positioning accuracy and the inability to discover and handle potential fault hazards in a timely manner. SUMMARY

[0005] The purpose of the present application is to provide a fault distinguishing method of a generator and a protection device, aiming to solve the technical problem that the protection system may malfunction due to the inability to accurately distinguish between voltage transformer circuit faults and bus system faults in the related technology.

[0006] In a first aspect, in order to achieve the above object, the present application provides a fault distinguishing method of a generator, which comprises the following steps: acquiring at least two voltage signals reflecting terminal voltage of the generator; acquiring stator current characteristics of the generator, wherein the stator current characteristics comprise stator current absolute value and stator current negative sequence component; when it is judged that the at least two voltage signals are both faulty, starting the following distinguishing step. The distinguishing step is specifically: judging whether the stator current absolute value of the generator is abnormal based on the stator current characteristics; if the stator current absolute value is not abnormal, determining that the fault type is a voltage signal acquisition fault; if the stator current absolute value is abnormal, determining that the fault type is a bus fault.

[0007] Through the above technical solution, after judging that the voltage signal is abnormal, the present application introduces analysis of the stator current characteristics of the generator, can accurately distinguish whether the fault is originated from the voltage signal acquisition loop itself or the bus system fault, thereby avoiding the protection system from making an erroneous protection action due to the measurement fault, and improving the stability and safety of the generator set and the power grid operation.

[0008] In a second aspect, the present application provides a protection device of a generator, which comprises: a voltage signal acquisition module, a current characteristic acquisition module and a logic judgment module. The voltage signal acquisition module is used for acquiring at least two voltage signals reflecting terminal voltage of the generator. The current characteristic acquisition module is used for acquiring stator current characteristics of the generator, wherein the stator current characteristics comprise stator current absolute value and stator current negative sequence component. The logic judgment module is connected with the voltage signal acquisition module and the current characteristic acquisition module, and is used for, when it is judged that the at least two voltage signals are both faulty, judging the running state of the generator based on the stator current absolute value in the stator current characteristics, if the stator current absolute value is not abnormal, determining that the fault type is a voltage signal acquisition fault, and if the stator current absolute value is abnormal, determining that the fault type is a bus fault.

[0009] In a third aspect, the present application further provides a protection device of a generator, which comprises: a processor, and a memory connected with the processor. The memory stores computer program instructions, and the computer program instructions are executed by the processor to realize the fault distinguishing method of any one of the preceding aspects.

[0010] In some embodiments, when the fault type is determined to be a bus fault, the fault distinguishing method further comprises the following steps: judging whether the stator current negative sequence component is abnormal based on the stator current characteristics; if the negative sequence component is not abnormal, determining that the fault type is a bus symmetric fault; if the negative sequence component is abnormal, determining that the fault type is a bus asymmetric fault.

[0011] In some embodiments, the fault distinguishing method further comprises the steps of: when it is determined that there is a fault signal in at least two voltage signals and there is a normal signal, determining that the fault type is a partial voltage signal acquisition fault; and locking the forced excitation signal and generating an alarm signal.

[0012] In some embodiments, when it is determined that the fault type is a bus symmetric fault, the fault distinguishing method further comprises issuing a generator tripping instruction.

[0013] In some embodiments, when it is determined that the fault type is a bus asymmetric fault, the fault distinguishing method further comprises triggering a forced excitation action and generating an alarm signal.

[0014] In some embodiments, when it is determined that the fault type is a voltage signal acquisition fault, the fault distinguishing method further comprises controlling the generator to switch to a constant current operation mode or a manual operation mode.

[0015] In some embodiments, the stator current negative sequence component is obtained by Fourier transform calculation on three-phase stator currents of the generator.

[0016] In some embodiments, the stator current characteristic is from a current transformer (CT) electrically connected to the generator. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0018] Figure 1 is a flowchart of a generator fault distinguishing method provided by the present application; Figure 2 is a flowchart of another generator fault distinguishing method provided by the present application; Figure 3 is a block diagram of a generator protection device provided by the present application; Figure 4 is a block diagram of another generator protection device provided by the present application.

[0019] Reference signs: 110, voltage signal acquisition module; 120, current characteristic acquisition module; 130, logic judgment module; 200, processor; 300, memory. DETAILED DESCRIPTION

[0020] The application will be described in further detail below with reference to the drawings and embodiments. It is particularly pointed out that the following embodiments are only for illustration of the application and do not limit the scope of the application. Similarly, the following embodiments are only part of the embodiments of the application, and all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the application.

[0021] Reference herein to "embodiment" means that the particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily mutually exclusive of other embodiments. It is explicitly and implicitly understood that the embodiments described herein are capable of combination and that individual features, structures, or characteristics of the embodiments can be combined with features, structures, or characteristics of other embodiments.

[0022] The embodiments of the application provide a fault distinguishing method and a protection device of a generator. It can be understood that the generator, for example, a synchronous generator, is a main device for converting other forms of energy into electric energy in a power system, and its stable operation is crucial for the safety of the power grid.

[0023] For ease of description, the following embodiments will be described by taking a steam turbine generator as an example. It should be understood by those skilled in the art that the technical solutions disclosed in the application are not limited to steam turbine generators. The solutions are also applicable to other types of synchronous generators, such as hydroelectric generators, gas turbine generators, etc. When applied to different types of generators, only the relevant thresholds in the solutions need to be adjusted according to the rated parameters and operating characteristics of the specific generator. Different types of generators do not affect the implementation of the basic technical concept of the application.

[0024] Please refer to Figure 1 , Figure 1 A flowchart of a fault distinguishing method of a generator provided by the application is shown in FIG. 1. In an embodiment, the fault distinguishing method can include steps S100, S200, S300, S400, S410, and S420.

[0025] Step S100: Obtain at least two voltage signals reflecting the terminal voltage of the generator.

[0026] In one embodiment, in order to monitor and control the operating state of the generator, it is necessary to obtain the generator terminal voltage information in real time. In order to ensure the reliability of the voltage signal and avoid misjudgment of the protection system due to partial measurement loop failure, the fault distinguishing method obtains at least two voltage signals by setting mutually redundant measurement loops. The beneficial effect of this redundant configuration is that when one of the voltage signals becomes unreliable due to measurement loop failure, the protection system can still refer to the other or the remaining normal voltage signal, thereby ensuring the continuity and accuracy of the voltage feedback and avoiding system out-of-control due to single-point measurement failure.

[0027] In some embodiments, the two voltage signals can come from two independent voltage transformers (PTs). For example, an excitation PT and an instrument PT, or two PTs with the same function, can be configured to measure the same set of voltages at the generator outlet. The two signals are sent to the protection device in parallel as a reference for subsequent fault judgment.

[0028] In one embodiment, in order to further improve the response capability to partial PT failure, a voltage monitoring module can also be provided on the basis of the double PT. The function of the voltage monitoring module is to compare the voltage signals from different PTs in real time. When the voltage monitoring module detects that one of the PT signals is abnormal (such as signal loss or significant deviation in amplitude from other signals), it can quickly identify that it is a partial PT failure. At this time, the module can immediately trigger an alarm signal to prompt the operator, and the module can also output a blocking signal at the same time to block or close the forced excitation function of the excitation system. In this way, it can effectively prevent the protection system from executing an incorrect forced excitation action due to misjudgment of partial PT failure as a voltage collapse of the power grid, thereby avoiding adverse effects on the generator equipment and the power grid.

[0029] Step S200, obtaining the stator current characteristics of the generator.

[0030] In addition to the voltage signal, the stator current is another physical quantity that can more directly reflect the real electromagnetic state of the generator and the external power grid working condition. Therefore, the fault distinguishing method of the present application also includes obtaining the stator current characteristics of the generator as a reference for fault identification when the voltage signal is abnormal.

[0031] In one embodiment, the stator current feature can come from a Current Transformer (CT) electrically connected to the stator winding of the generator. The CT converts the large current at the generator outlet into a small current signal that can be processed by the protection device. The acquired three-phase stator current signals can be used to calculate a variety of feature parameters that can represent the fault type. In this application, the stator current feature specifically includes the absolute value of the stator current and the negative sequence component of the stator current.

[0032] It can be understood that the stator current in this application refers to the three-phase alternating current output from the winding of the fixed part of the generator (i.e. the stator), which is the direct carrier of the power delivered by the generator to the power grid. In the normal operating state, the three-phase current is equal in size and 120 degrees out of phase, showing a symmetrical and balanced characteristic.

[0033] In this application, the absolute value of the stator current refers to the effective value or amplitude of the three-phase stator current. This parameter directly reflects the size of the current flowing through the stator winding of the generator. When the external power grid experiences a serious fault such as a short circuit, the absolute value of the stator current will usually increase instantaneously and far exceed its rated operating current. Therefore, by monitoring whether the absolute value of the stator current is abnormal, it can be effectively determined whether the power grid system is in a serious fault state.

[0034] In this application, the negative sequence component of the stator current refers to an important indicator for measuring the degree of imbalance of three-phase current. According to the symmetrical component method, any set of asymmetric three-phase sinusoidal quantities can be decomposed into three symmetrical components: positive sequence, negative sequence and zero sequence. Among them, the size of the negative sequence component directly reflects the degree of asymmetry of the system. When the generator is completely normal and the power grid system is also in a symmetrical and balanced state, the negative sequence component of the stator current is theoretically zero or close to zero. When the power grid experiences an asymmetric fault (e.g. single-phase or two-phase short circuit), the balance of the three-phase current is destroyed, and a significant negative sequence component will be generated. Therefore, by calculating and monitoring the size of the negative sequence component of the stator current, it can be accurately determined whether the power grid has experienced an asymmetric fault.

[0035] In one embodiment, the calculation of the negative sequence component of the stator current can be achieved by performing Fourier Transform on the discrete sampling values of the three-phase stator current acquired by the protection device. Through the Fourier Transform algorithm, the current signal in the time domain can be converted to the frequency domain, so that the size and phase of the negative sequence component can be easily separated and calculated, providing a basis for subsequent fault judgment.

[0036] Step S300, the voltage signal is faulty.

[0037] The embodiments of the present application consider the case where all voltage signals are faulty. Specifically, whether the voltage signals are faulty can be comprehensively determined based on various criteria. Those skilled in the art can understand that, for example, a commonly used criterion is a low voltage criterion, that is, when the amplitude of one or more voltage signals, after excluding normal operation fluctuations, continuously falls below a preset low voltage threshold and maintains for a short time delay, it can be determined that the voltage signal is faulty, wherein the signal amplitude directly becomes zero is a special case of the criterion. In addition, since the system obtains at least two redundant voltage signals, a signal comparison criterion can also be introduced. The criterion calculates the difference between the effective values of the two voltage signals in real time, and when the difference exceeds a preset setting value, it indicates that at least one signal is not reliable. At the same time, in addition to the amplitude information, the phase abnormal criterion can also be used as an auxiliary judgment basis, when the phase of a certain signal compared with other signals appears abnormal, that is, the offset exceeds the preset range, it can also be determined that the signal is faulty.

[0038] In the embodiments of the present application, step S300 indicates that all obtained voltage signals meet one or more of the above fault criteria.

[0039] The fault distinguishing method enters step S400, that is, to determine whether the absolute value of the stator current of the generator is abnormal, to further identify the cause of the fault.

[0040] In step S400, the protection device will make a first-level logical judgment on the actual operating state of the generator based on the stator current characteristics obtained in step S200, specifically based on the absolute value of the stator current. As the direct carrier of energy output from the stator winding of the generator to the power grid, the absolute value of the stator current is the most intuitive indicator to determine whether the generator is in a serious fault condition. In an embodiment, the way to determine whether the absolute value of the stator current is abnormal can be to compare it with the rated current value of the generator.

[0041] If it is determined through comparison that the absolute value of the stator current is not abnormal, for example, its value is still within the normal fluctuation range of the rated current, it indicates that the generator itself and the external power grid system connected thereto have not occurred a serious fault that can cause a sharp increase in current. In this case, since the power grid and the generator are healthy, the phenomenon of simultaneous failure of all voltage signals detected before can be attributed to the voltage signal acquisition circuit itself. Therefore, at this time, step S420 is performed, that is, to determine the fault type as a voltage signal acquisition fault.

[0042] If an abnormality is detected in the absolute value of the stator current, such as a value significantly exceeding the rated current, it indicates that the generator is transmitting fault current to the external power grid. This situation suggests that the fault originates from the external bus system. Therefore, step S410 is performed, determining the fault type as a bus fault. Since bus faults can be further subdivided into symmetrical bus faults and asymmetrical bus faults, and the hazards and countermeasures for these two types are not entirely the same, in some embodiments, the specific type of bus fault can be further distinguished based on other physical quantities.

[0043] As described above, the embodiments above provide a generator fault differentiation method through steps S100 to S420. The core of this method lies in the fact that when it is confirmed that all voltage measurement signals have failed, thus rendering voltage signals unreliable as a basis for fault judgment, the fault type is differentiated by introducing analysis of the generator stator current characteristics, particularly utilizing the analysis of the absolute value of the stator current. Specifically, this fault differentiation method can accurately distinguish whether the fault originates from the voltage signal acquisition circuit itself (i.e., PT fault) or from an external bus system fault. This fault differentiation method effectively prevents erroneous protection actions triggered by misjudgment in the protection system, greatly improving the overall stability and safety of the generator set and the power grid operation.

[0044] Please see Figure 2 , Figure 2 This is a flowchart illustrating another generator fault differentiation method provided in this application.

[0045] It should be noted that steps S100, S200, S300, S400, S410, and S420 in this embodiment are basically the same as those in the previous embodiments, and will not be repeated here. Compared with the previous embodiments, this embodiment provides a more comprehensive and detailed fault judgment logic, and gives specific response strategies for different fault types. Specifically, the logic of this fault differentiation method is as follows: In one embodiment, before step S300, there may be a judgment step S310, which determines whether there is a voltage signal fault. If it is determined that there is no voltage signal fault, it can be determined that the current generator is not faulty, and at this time, the voltage signal at the generator end can continue to be acquired, that is, step S100 can continue to be executed.

[0046] Understandably, if a voltage signal fault is determined in step S310, step S320 needs to be further executed to determine whether all voltage signals are faulty. If the result of step S320 is "no," meaning that a fault signal exists in the system but not all voltage signals are faulty, then step S321 is executed to determine that the fault can be identified as a partial voltage signal acquisition fault. At this time, the process executes step S322, which shuts down the forced excitation signal and generates an alarm signal. In this step, the protection device will execute the corresponding protection strategy, such as outputting an alarm signal to alert the operators, and simultaneously shutting down or blocking the forced excitation signal to prevent misoperation caused by inconsistent measurement signals.

[0047] If the judgment result of step S320 is "yes", then step S300 proceeds, indicating that the voltage signals have all failed. In one embodiment, the fault differentiation method continues to execute step S400. If, in step S400, it is determined that the absolute value of the generator stator current is not abnormal, it indicates that the fault originates from the voltage signal acquisition circuit itself. At this time, step S420 proceeds, and step S421 is executed, i.e., controlling the generator to switch to constant current operation mode or manual operation mode. In step S421, in order to maintain stable generator operation in the event of loss of voltage feedback, the protection device will control the generator to switch from automatic voltage regulation mode to constant current operation mode or manual operation mode.

[0048] If, in step S400, it is determined that the absolute value of the generator stator current is abnormal, then step S410 proceeds, i.e., the fault type is determined to be a bus fault. In one embodiment, the fault differentiation method continues to execute step S500. Step S500 will determine whether the negative sequence component of the generator stator current is abnormal based on the negative sequence component in the stator current characteristics, in order to further differentiate the specific type of bus fault.

[0049] In one embodiment, the negative sequence component is determined to be abnormal by comparing its magnitude with a preset threshold. Taking a steam turbine generator as an example, its long-term allowable negative sequence current is usually between 6% and 8% of the rated current. In order to leave sufficient operating margin and ensure protection performance, the threshold of the negative sequence component can be set to 5% of the rated stator current.

[0050] If the negative sequence component of the stator current is determined to be abnormal in step S500, step S521 is performed, i.e., the fault type is determined to be a bus symmetric fault. The bus symmetric fault usually refers to a three-phase short circuit on the bus, such as a three-phase metallic short circuit. The electrical characteristic of this type of fault is that the amplitudes of the three-phase short circuit currents are large and equal, and the phases are 120 degrees apart. The system remains symmetric in the fault state, and thus no significant negative sequence current component is generated. At this time, the fault distinguishing method performs step S522, and the protection device issues a generator tripping instruction to quickly disconnect the generator from the fault system.

[0051] On the contrary, if the negative sequence component of the stator current is determined to be abnormal in step S500, step S510 is performed, i.e., the fault type is determined to be a bus asymmetric fault. The bus asymmetric fault refers to a one-phase or two-phase short circuit on the bus, such as a single-phase grounding short circuit or a two-phase interphase short circuit. The electrical characteristic of this type of fault is that the amplitudes of the three-phase currents are no longer equal, and the phase relationship is also disordered, and the system presents serious asymmetry, thereby generating a significant negative sequence current component. The fault distinguishing method continues to perform step S511, and the protection device triggers a forced excitation action to support the grid voltage and simultaneously generates an alarm signal.

[0052] Referring to Figure 3 , Figure 3 A block diagram of a generator protection device is provided in the present application. The present application also provides a protection device for a generator. In an embodiment, the protection device can include a voltage signal acquisition module 110, a current characteristic acquisition module 120, and a logic judgment module 130.

[0053] The voltage signal acquisition module 110 is configured to acquire at least two voltage signals reflecting the terminal voltage of the generator.

[0054] The current characteristic acquisition module 120 is configured to acquire the stator current characteristic of the generator. In an embodiment, the stator current characteristic includes the stator current absolute value and the negative sequence component of the stator current.

[0055] The logic judgment module 130 is connected to the voltage signal acquisition module 110 and the current characteristic acquisition module 120. The logic judgment module 130 is configured to start a distinguishing logic when it is determined that the at least two voltage signals have occurred simultaneously. The distinguishing logic is specifically: determining the operating state of the generator based on the stator current absolute value in the stator current characteristic; if the stator current absolute value is determined to be abnormal, determining the fault type to be a voltage signal acquisition fault; and if the stator current absolute value is determined to be abnormal, determining the fault type to be a bus fault.

[0056] It should be noted that the protection device composed of the voltage signal acquisition module 110, the current characteristic acquisition module 120 and the logic judgment module 130 can be used to execute the generator fault distinguishing method in any of the foregoing embodiments. The functions of these modules can be realized by hardware circuit, software program or a combination of both.

[0057] Please refer to Figure 4 , Figure 4 Another block diagram of a generator protection device is provided in the present application.

[0058] The present application also provides a protection device for a generator. In one embodiment, the protection device can include a processor 200 and a memory 300 connected to the processor 200.

[0059] The processor 200 can be a central processing unit (CPU), a digital signal processor (DSP) or a field programmable gate array (FPGA) and other hardware units with data processing and logic operation capabilities.

[0060] The memory 300 can be a combination of one or more storage media such as random access memory (RAM), read-only memory (ROM) or flash memory. The memory 300 stores computer program instructions.

[0061] When the protection device is running, the processor 200 reads and executes the computer program instructions stored in the memory 300 to realize the generator fault distinguishing method in any of the foregoing embodiments. For example, the processor 200 can realize the functions of acquiring voltage signals and stator current characteristics, logically judging the fault type and outputting corresponding control instructions by executing program instructions.

[0062] It should be noted that the terms "first", "second", "third" in the present application are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second", "third" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0063] The above only describes some embodiments of the present application, and does not limit the protection scope of the present application, and any equivalent device or equivalent process transformation using the contents of the present application specification and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for fault differentiation of a generator, [Wispro1] characterized in that, The fault differentiation method includes the following steps: Acquire at least two voltage signals reflecting the generator terminal voltage; Obtain the stator current characteristics of the generator; wherein, the stator current characteristics include the absolute value of the stator current and the negative sequence component of the stator current; When it is determined that all the voltage signals are faulty, the following differentiation steps are performed: Based on the stator current characteristics, determine whether the absolute value of the generator's stator current is abnormal; If the absolute value of the stator current is not abnormal, the fault type is determined to be a voltage signal acquisition fault. If the absolute value of the stator current is abnormal, the fault type is determined to be a bus fault.

2. The fault differentiation method according to claim 1, characterized in that, When the fault type is determined to be a bus fault, the fault differentiation method further includes the following steps: Based on the stator current characteristics, determine whether the negative sequence component of the stator current is abnormal; If the negative sequence component does not exhibit any abnormality, the fault type is determined to be a bus symmetrical fault. If the negative sequence component is abnormal, the fault type is determined to be a bus asymmetry fault.

3. The fault differentiation method according to claim 1, characterized in that, The fault differentiation method further includes the following steps: When it is determined that both fault signals and normal signals exist in the voltage signal, the fault type is determined to be a partial voltage signal acquisition fault; and the forced excitation signal is turned off and an alarm signal is generated.

4. The fault differentiation method according to claim 2, characterized in that, When the fault type is determined to be a busbar symmetrical fault, the fault differentiation method further includes the following steps: Issue a generator trip command.

5. The fault differentiation method according to claim 2, characterized in that, When the fault type is determined to be a bus asymmetrical fault, the fault differentiation method further includes the following steps: It triggers forced excitation and generates an alarm signal.

6. The fault differentiation method according to claim 1, characterized in that, When the fault type is determined to be a voltage signal acquisition fault, the fault differentiation method further includes the following steps: Control the generator to switch to constant current operation mode or manual operation mode.

7. The fault differentiation method according to claim 1, characterized in that, The negative sequence component of the stator current is obtained by performing a Fourier transform on the three-phase stator current of the generator.

8. The fault differentiation method according to claim 1, characterized in that, The stator current characteristic originates from the current transformer electrically connected to the generator.

9. A protection device for a generator, characterized in that, The protective device includes: A voltage signal acquisition module is used to acquire at least two voltage signals that reflect the generator terminal voltage. A current characteristic acquisition module is used to acquire the stator current characteristics of the generator, wherein the stator current characteristics include the absolute value of the stator current and the negative sequence component of the stator current. The logic judgment module is connected to the voltage signal acquisition module and the current feature acquisition module, and the logic judgment module is used for: When it is determined that all the voltage signals are faulty, the following distinction logic applies: The operating status of the generator is determined based on the absolute value of the stator current in the stator current characteristics. If the absolute value of the stator current is not abnormal, the fault type is determined to be a voltage signal acquisition fault. If the absolute value of the stator current is abnormal, the fault type is determined to be a bus fault.

10. A protection device for a generator, characterized in that, include: processor; as well as A memory connected to the processor; The memory stores computer program instructions for implementing the fault differentiation method as described in any one of claims 1 to 8.

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