System and method for blocking power generator stator ground protection action

Abstract

The present application relates to the technical field of relay protection, and provides a system and method for blocking a power generator stator ground protection action. The system comprises: a power generator, an enclosed bus, a power generator outlet voltage transformer, a power generator outlet circuit breaker, a first bus, a plant reactor, a second bus, a plant work incoming circuit breaker, a plant standby incoming circuit breaker, a plant bus section, and a plant power switching device, wherein the power generator is connected to one side of the power generator outlet circuit breaker by means of the enclosed bus and the power generator outlet voltage transformer, and the other side of the power generator outlet circuit breaker is connected to one side of the plant reactor by means of the first bus; the other side of the plant reactor is connected to the plant work incoming circuit breaker by means of the second bus, the plant work incoming circuit breaker and the plant standby incoming circuit breaker are jointly connected to the plant bus section, and the plant power switching device is connected between the plant work incoming circuit breaker and the plant standby incoming circuit breaker.

Description

System and method for blocking generator stator ground fault protection

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on February 29, 2024, with application number 202410228791.7 and invention name “System and method for locking generator stator grounding protection action”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of relay protection technology, and in particular to a system and method for locking a generator stator grounding protection action. Background Art

[0004] When a plant reactor is connected to the generator outlet, the high-voltage plant section is isolated from the generator by the reactor. At this point, the high-voltage plant section is equivalent to an ungrounded system. When a ground fault occurs in the high-voltage plant section load, the fault current is small. Typically, the zero-sequence overcurrent protection for the high-voltage plant section load operates before signaling. In this case, when a single-phase direct ground fault occurs in the high-voltage plant section load, the zero-sequence overcurrent protection operates before signaling and fails to isolate the fault point in a timely manner. This significantly increases the zero-sequence voltage at the generator terminal (neutral point), which can easily cause the generator stator ground fault protection to malfunction at the outlet.

[0005] In the wiring mode of connecting the generator outlet to the plant reactor, the existing generator stator grounding protection has the following defects and deficiencies:

[0006] (1) Inaccurate judgment of the ground fault location. When a direct ground fault occurs in the high-voltage plant load, the generator stator ground fault protection cannot accurately determine that the ground fault is outside the protection range due to the use of reactors for isolation. There is a risk of false tripping of the generator stator ground fault protection.

[0007] (2) Increased risk of generator damage. Some power plants use the generator stator grounding protection as a signal. When a ground fault occurs in the generator stator winding, the operator will first locate the ground fault location before shutting down the generator. If the fault current is not eliminated for a long time, there is a risk of burning the generator.

[0008] Summary of the Invention

[0009] The present application provides a multi-level data monitoring method, apparatus, device and storage medium, aiming to solve at least one of the technical problems in the related art to a certain extent.

[0010] In a first aspect, the present application provides a system for blocking a generator stator ground fault protection action, comprising:

[0011] Generator, enclosed busbar, generator outlet voltage transformer, generator outlet circuit breaker, first busbar, plant reactor, second busbar, plant service incoming line circuit breaker, plant standby incoming line circuit breaker, plant busbar section and plant power switching device, among which,

[0012] The generator is connected to one side of the generator output circuit breaker via the enclosed busbar and the generator output voltage transformer, and the other side of the generator output circuit breaker is connected to one side of the plant reactor via the first busbar;

[0013] The other side of the plant reactor is connected to the plant working incoming line circuit breaker through the second busbar. The plant working incoming line circuit breaker and the plant standby incoming line circuit breaker are connected to the plant busbar section together. The plant power switching device is connected between the plant working incoming line circuit breaker and the plant standby incoming line circuit breaker.

[0014] Optionally, the plant working incoming line circuit breaker and the plant standby incoming line circuit breaker are not closed at the same time. In the first case, the plant working incoming line circuit breaker is closed to connect the plant bus section.

[0015] Optionally, in the second case, the plant standby incoming line circuit breaker is closed to connect the plant bus section.

[0016] Optionally, the first situation is used to characterize a normal situation, and the second situation is used to characterize an abnormal situation.

[0017] Optionally, the plant power switching device is used to control the switching process between the plant working incoming line circuit breaker and the plant standby incoming line circuit breaker.

[0018] Optionally, in the working state, the generator, the generator output voltage transformer, the plant reactor and the plant power switching device operate normally, the generator end circuit breaker and the plant working incoming line circuit breaker are closed, and the plant standby incoming line circuit breaker is open.

[0019] Optionally, when the zero-sequence voltage collected by the generator output voltage transformer reaches the generator stator grounding protection starting value, the plant power switching device is activated to switch the plant power, the plant working incoming line circuit breaker is opened, and the plant standby incoming line circuit breaker is closed.

[0020] Optionally, if the stator grounding protection is still activated after the auxiliary power is switched, the generator stator grounding protection is allowed to be activated and shut down.

[0021] Optionally, if the stator grounding protection returns after the factory power is switched, it is determined that the fault point is at the load-bearing part of the factory bus section, and a factory bus grounding alarm signal is issued and the generator stator grounding protection is locked and shut down.

[0022] In a second aspect, the present application provides a method for locking a generator stator ground fault protection action, comprising the following steps:

[0023] If the zero-sequence voltage at the generator terminal reaches the starting value of the generator stator grounding protection, the auxiliary power switching device will be activated to switch the auxiliary power;

[0024] If the stator grounding protection is still activated after the auxiliary power is switched, the generator stator grounding protection is allowed to be activated and shut down;

[0025] If the stator grounding protection returns after the auxiliary power is switched, it is judged that the fault point is at the load carried by the auxiliary bus section, and an auxiliary bus grounding alarm signal is issued and the stator grounding protection of the generator is locked and shut down.

[0026] This application has at least the following beneficial technical effects:

[0027] 1. Accurately determine the location of ground faults. When the generator outlet is connected to the plant reactor, this application effectively determines the location of the ground fault by disconnecting the plant section from the generator end after the plant power is switched. This prevents misjudgment of the generator stator ground fault protection when a ground fault occurs on the plant busbar load.

[0028] 2. Strong adaptability. This application is highly practical and does not require additional primary equipment. It is applicable to all relay protection devices.

[0029] 3. Accurate identification results: This application uses a reliable identification method to identify the location of the ground fault, thereby accurately determining whether the generator is faulty.

[0030] To sum up, when the generator outlet is connected to the plant reactor, this application solves the problem of false operation of the generator stator grounding protection when the plant bus load is grounded, and has the advantages of reasonable outlet method, accurate judgment and strong adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0032] FIG1 is a schematic structural diagram of a system for blocking a generator stator ground fault protection action according to a first embodiment of the present application;

[0033] FIG2 is a flow chart of a method for blocking a generator stator ground fault protection action according to a second embodiment of the present application;

[0034] FIG3 is a flow chart of another method for locking a generator stator ground fault protection action according to a second embodiment of the present application.

[0035] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0036] The embodiments of the present application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present application and are not to be construed as limiting the present application. On the contrary, the embodiments of the present application include all variations, modifications, and equivalents that fall within the spirit and scope of the appended claims.

[0037] Generator stator ground fault protection is used to respond to generator stator ground faults. It uses the zero-sequence voltage at the generator terminal (neutral point) as its criterion. When a ground fault occurs in the generator stator winding, a zero-sequence voltage will appear at the generator terminal (neutral point). When the zero-sequence voltage reaches the action value, the generator stator ground fault protection determines that the generator stator winding is grounded and activates, triggering a shutdown.

[0038] When the generator outlet is connected to a high-voltage auxiliary transformer, the high-voltage auxiliary section is isolated from the generator by the high-voltage auxiliary transformer. Typically, the neutral point on the low-voltage side of the high-voltage auxiliary transformer is grounded with a low resistance. Zero-sequence overcurrent protection is activated on the low-voltage side of the high-voltage auxiliary transformer as primary protection for single-phase grounding faults on the low-voltage side of the high-voltage auxiliary transformer and as backup protection for single-phase grounding faults in the high-voltage auxiliary section load, and this protection activates to shut down the generator. Simultaneously, zero-sequence overcurrent protection is activated on the high-voltage auxiliary section load as primary protection for single-phase grounding faults, and this protection activates by tripping the high-voltage circuit breaker for that load. With this wiring arrangement, when a single-phase grounding fault occurs in the high-voltage auxiliary section load, the zero-sequence overcurrent protection activates promptly. Furthermore, due to the isolation of the high-voltage auxiliary transformer, the zero-sequence voltage at the generator terminal and neutral point will not increase significantly. Therefore, the generator stator winding grounding protection will not malfunction in the event of a single-phase grounding fault in the high-voltage auxiliary section load.

[0039] It should be noted that the executor of the multi-level data monitoring method of this embodiment can be a multi-level data monitoring device, which can be implemented by software and / or hardware. The device can be configured in an electronic device, and the electronic device can include but is not limited to a terminal, a server, etc.

[0040] FIG1 is a system for blocking the stator ground fault protection of a generator according to the first embodiment of the present application, comprising: a generator 1, a closed busbar 2, a voltage transformer at the generator output 3, a circuit breaker at the generator output 4, a first busbar 5, a plant reactor 6, a second busbar 7, a plant working incoming line circuit breaker 8, a plant standby incoming line circuit breaker 9, a plant busbar section 10, and a plant power switching device 11, wherein:

[0041] The generator is connected to one side of the generator output circuit breaker via the enclosed busbar and the generator output voltage transformer, and the other side of the generator output circuit breaker is connected to one side of the plant reactor via the first busbar;

[0042] The other side of the plant reactor is connected to the plant working incoming line circuit breaker through the second busbar. The plant working incoming line circuit breaker and the plant standby incoming line circuit breaker are connected to the plant busbar section. The plant power switching device is connected between the plant working incoming line circuit breaker and the plant standby incoming line circuit breaker.

[0043] Optionally, the plant service incoming line circuit breaker and the plant service standby incoming line circuit breaker are not closed at the same time. In the first case, the plant service incoming line circuit breaker is closed to connect the plant busbar section.

[0044] Optionally, in the second case, the plant's standby incoming line circuit breaker is closed to connect the plant busbar section.

[0045] Optionally, the first situation is used to characterize a normal situation, and the second situation is used to characterize an abnormal situation.

[0046] Optionally, the plant power switching device is used to control the switching process between the plant working incoming line circuit breaker and the plant standby incoming line circuit breaker.

[0047] Optionally, in the working state, the generator, the generator output voltage transformer, the plant reactor and the plant power switching device operate normally, the generator end circuit breaker and the plant working incoming line circuit breaker are closed, and the plant standby incoming line circuit breaker is open.

[0048] The plant power switching device is mainly used to control the switching process between the plant service incoming line circuit breaker and the plant standby incoming line circuit breaker to ensure that there will be no power interruption in the plant bus section during switching. Generally speaking, the device consists of the following parts:

[0049] It should be noted that the auxiliary power switching device may include a controller responsible for determining the current status of the auxiliary power incoming circuit breaker, monitoring changes in external electrical signals, and outputting corresponding control signals. Its primary function is to ensure a smooth switching process and avoid power interruptions.

[0050] The power supply system can provide the necessary power support for the factory power switching device to prevent it from failing to work properly in the event of a power outage.

[0051] The signal detection module can be mainly used to detect external electrical signals and feed back the detected results to the controller so that the controller can adjust the control strategy in time according to the changes in the signal.

[0052] Brakes and contactors are mainly used to switch between circuit breakers and switches, and to connect and disconnect the factory busbar.

[0053] Optionally, when the zero-sequence voltage collected by the generator output voltage transformer reaches the generator stator grounding protection starting value, the plant power switching device is started to switch the plant power, the plant working incoming line circuit breaker is opened, and the plant standby incoming line circuit breaker is closed.

[0054] When the zero-sequence voltage collected by the generator output voltage transformer reaches the generator stator grounding protection start value, the auxiliary power switching device is activated to switch the auxiliary power. The specific operation is as follows:

[0055] Under normal operating conditions, the generator, generator output voltage transformer, auxiliary reactor, and auxiliary power switching device all function normally. The generator-side circuit breaker and auxiliary power supply circuit breaker are closed to ensure normal power supply. The zero-sequence voltage detected by the generator output voltage transformer is monitored. When the zero-sequence voltage reaches the generator stator ground fault protection trigger value, a start signal is triggered. This start signal is transmitted to the auxiliary power switching device controller. Based on the received start signal, the auxiliary power switching device controller executes the corresponding control strategy. The controller outputs a signal to open the auxiliary power supply circuit breaker, switching the load from the working power supply to the backup power supply. Simultaneously, the auxiliary power supply circuit breaker is closed, connecting the backup power source to the auxiliary busbar section, ensuring power is not lost during the switchover process. Through these steps, when the zero-sequence voltage detected by the generator output voltage transformer reaches the generator stator ground fault protection trigger value, the auxiliary power switching device is automatically triggered to perform power switching, ensuring power is not lost during the switchover process. This ensures the continuity and stability of industrial production.

[0056] Optionally, if the stator grounding protection is still activated after the auxiliary power is switched, the generator stator grounding protection is allowed to be activated and shut down.

[0057] Optionally, if the stator grounding protection returns after the factory power is switched, it is determined that the fault point is at the loaded factory bus section, and a factory bus grounding alarm signal is issued and the generator stator grounding protection is locked and shut down.

[0058] FIG2 is a flow chart of a method for multi-level data monitoring for blocking a generator stator ground fault protection action according to a second embodiment of the present application. As shown in FIG2 , the method includes:

[0059] S201: If the zero-sequence voltage at the generator terminal reaches the starting value of the generator stator grounding protection, the auxiliary power switching device is started to operate and perform auxiliary power switching.

[0060] S202: If the stator grounding protection is still activated after the auxiliary power is switched, the generator stator grounding protection is allowed to be activated and shut down.

[0061] S203: If the stator grounding protection returns after the auxiliary power is switched, it is determined that the fault point is at the load carried by the auxiliary bus section, and an auxiliary bus grounding alarm signal is issued and the generator stator grounding protection is locked and shut down.

[0062] It should be noted that if the generator stator grounding protection still operates after the auxiliary power is switched, the following measures can be taken:

[0063] The generator stator ground fault protection is allowed to shut down. Once the stator ground fault protection is activated, the generator can be stopped to avoid potential safety hazards caused by continued power supply. At this point, the problem needs to be investigated and the relevant fault needs to be repaired before the generator can be restarted. Furthermore, if the stator ground fault protection returns after the auxiliary power is switched on and the fault is determined to be located in a loaded auxiliary bus section, the following measures can be taken to issue an auxiliary bus ground fault alarm signal: When the fault is determined to be located in a loaded auxiliary bus section, an alarm signal can be issued to alert relevant personnel and enable them to take appropriate emergency measures. The generator stator ground fault protection is locked out. To prevent the fault from further affecting system operation and safety, measures can be taken to disable the generator stator ground fault protection so that it no longer activates. This can avoid the impact of frequent shutdowns and restarts on system stability.

[0064] It's important to note that when stator ground fault protection activates or fails, detailed fault analysis and troubleshooting must be performed, and appropriate remedial measures must be implemented to ensure system operation and personnel safety. Furthermore, before shutting down a generator due to stator ground fault protection, a comprehensive assessment and verification of influencing factors is required to ensure that disabling the protection device will not create other potential hazards.

[0065] FIG3 is a flow chart of another method for locking a generator stator ground fault protection action according to an embodiment of the present application, comprising the following steps:

[0066] Step S101: The zero-sequence voltage at the generator terminal reaches the starting value of the generator stator ground fault protection, and the process proceeds to the next step;

[0067] Step S102: Start the auxiliary power switching device to switch the auxiliary power, and then determine whether the stator grounding protection is still in effect.

[0068] Step S103: If the stator grounding protection is still activated after the auxiliary power is switched, the generator is allowed to shut down due to the stator grounding protection.

[0069] In step S104, if the stator grounding protection returns after the auxiliary power is switched, it is determined that the fault point is at the load carried by the auxiliary bus section, and a "auxiliary bus grounding" alarm signal is issued and the generator stator grounding protection is locked and shut down.

[0070] This application has at least the following beneficial technical effects:

[0071] 1. Accurately determine the location of ground faults. When the generator outlet is connected to the plant reactor, this application effectively determines the location of the ground fault by disconnecting the plant section from the generator end after the plant power is switched. This prevents misjudgment of the generator stator ground fault protection when a ground fault occurs on the plant busbar load.

[0072] 2. Strong adaptability. This application is highly practical and does not require additional primary equipment. It is applicable to all relay protection devices.

[0073] 3. Accurate identification results: This application uses a reliable identification method to identify the location of the ground fault, thereby accurately determining whether the generator is faulty.

[0074] In summary, when the generator outlet is connected to the plant reactor, the present application solves the problem of malfunction of the generator stator grounding protection when the plant bus load is grounded, and has the advantages of reasonable export mode, accurate judgment, and strong adaptability. This application provides a system and method for locking the action of the generator stator grounding protection in response to the existing generator stator grounding protection, which may cause the generator stator grounding protection to malfunction when a direct grounding fault occurs in the high-voltage plant load. It is suitable for the connection mode of the generator outlet to the plant reactor, and improves the defect that the generator stator grounding protection may malfunction when a direct grounding fault occurs in the high-voltage plant load. It has the characteristics of no need for additional primary equipment and reasonable export mode.

[0075] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0076] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A system for locking the stator ground fault protection of a generator, characterized in that: include: Generator, enclosed busbar, generator outlet voltage transformer, generator outlet circuit breaker, first busbar, plant reactor, second busbar, plant service incoming line circuit breaker, plant standby incoming line circuit breaker, plant busbar section and plant power switching device, among which, The generator is connected to one side of the generator output circuit breaker via the enclosed busbar and the generator output voltage transformer, and the other side of the generator output circuit breaker is connected to one side of the plant reactor via the first busbar; The other side of the plant reactor is connected to the plant working incoming line circuit breaker through the second busbar. The plant working incoming line circuit breaker and the plant standby incoming line circuit breaker are connected to the plant busbar section together. The plant power switching device is connected between the plant working incoming line circuit breaker and the plant standby incoming line circuit breaker.

2. The system according to claim 1, wherein: The plant working incoming line circuit breaker and the plant standby incoming line circuit breaker are not closed at the same time. In the first case, the plant working incoming line circuit breaker is closed to connect the plant bus section.

3. The system according to claim 2, characterized in that In the second case, the auxiliary incoming line circuit breaker is closed and connected to the auxiliary bus section.

4. The system according to claim 3, characterized in that The first situation is used to represent a normal situation, and the second situation is used to represent an abnormal situation.

5. The system according to claim 2, wherein: The plant power switching device is used to control the switching process between the plant working incoming line circuit breaker and the plant standby incoming line circuit breaker.

6. The system according to claim 2, wherein: In the working state, the generator, the generator output voltage transformer, the plant reactor and the plant power switching device operate normally, the generator end circuit breaker and the plant working incoming line circuit breaker are closed, and the plant standby incoming line circuit breaker is open.

7. The system according to claim 6, characterized in that When the zero-sequence voltage collected by the generator output voltage transformer reaches the generator stator grounding protection starting value, the plant power switching device is activated to switch the plant power, the plant working incoming line circuit breaker is opened, and the plant standby incoming line circuit breaker is closed.

8. The system according to claim 6, wherein: If the stator grounding protection is still activated after the auxiliary power is switched, the generator stator grounding protection is allowed to shut down.

9. The system according to claim 6, wherein: If the stator grounding protection returns after the auxiliary power is switched, it is determined that the fault point is at the load-bearing part of the auxiliary bus section, and an auxiliary bus grounding alarm signal is issued, and the stator grounding protection of the generator is locked and shut down.

10. A method for locking a generator stator ground fault protection action, characterized in that: The steps include: If the zero-sequence voltage at the generator terminal reaches the starting value of the generator stator grounding protection, the auxiliary power switching device will be activated to switch the auxiliary power; If the stator grounding protection is still activated after the auxiliary power is switched, the generator stator grounding protection is allowed to be activated and shut down; If the stator grounding protection returns after the auxiliary power is switched, it is judged that the fault point is at the load carried by the auxiliary bus section, and an auxiliary bus grounding alarm signal is issued and the stator grounding protection of the generator is locked and shut down.

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