Grid-connected asynchronous protection method and system under special abnormal working condition

Abstract

The invention relates to a grid-connected asynchronous protection method under a special abnormal working condition, and the method comprises the following steps: obtaining a switching-on position signal of a circuit breaker at a synchronous point and voltage analog quantities at two sides of the circuit breaker, the voltage analog quantities comprising a three-phase voltage analog quantity at a generator side and a three-phase voltage analog quantity at a power grid side; and if it is detected that the switching-on position signal is changed from the switching-off position to the switching-on position, grid-connected asynchronous abnormal state judgment is executed in a preset monitoring time window. According to the technical scheme, the technical problem that a false grid-connected state cannot be identified and protected due to the fact that an isolation switch is not closed in place but a position contact is misreported in the prior art is solved, continuous monitoring of the actual grid-connected state of a system after a circuit breaker is closed is achieved, rapid removal can be achieved before a fault is developed into catastrophic breakdown, and the fault is prevented from being damaged. Electrical primary equipment such as a generator, a circuit breaker and an isolating switch is effectively protected, and equipment damage and power grid accidents caused by huge impact current and arc ablation are avoided.

Description

Technical Field

[0001] This invention relates to the field of power system relay protection technology, specifically to a method and system for grid-connected asynchronous protection under special abnormal operating conditions. Background Technology

[0002] In power system operation, generators, transformers, or tie lines need to be connected to the power system via circuit breakers or other switching equipment; this operation is called synchronization. Synchronization requires that the voltage amplitude, frequency, and phase on both sides of the circuit breaker switchgear meet the same or similar conditions. Currently, a synchronizing device is typically used to accomplish this operation. After detecting that the voltage on both sides of the connection point meets the connection conditions, the synchronizing device issues a closing command to achieve grid connection.

[0003] However, a special abnormal operating condition exists in the existing technology: before the circuit breaker closes, the isolating switch connected in series with the circuit breaker fails to fully close due to a mechanical or control circuit fault, but its position contact incorrectly sends a closing signal, causing the circuit breaker closing interlock to be released. At this time, the synchronizing device will still issue a closing command normally, and the circuit breaker closes normally. However, because the isolating switch is not actually connected, the generator and the power system are still electrically disconnected and have not achieved true parallel operation. In this abnormal operating condition, since the circuit breaker has closed, the synchronizing device has completed its work and exited, and can no longer monitor it. Existing relay protection devices do not have protection functions for this special state of "circuit breaker closed but system not actually connected". As time goes by, the phase and frequency difference of the voltage on both sides of the circuit breaker gradually increases, eventually causing the isolating switch gap to break down, generating huge inrush current and arc erosion, severely damaging the primary electrical equipment. In existing technologies, two main solutions are used to prevent asynchronous grid connection: For example, the generator synchronous grid connection control device disclosed in Chinese patent CN207896680U directly blocks the circuit breaker closing circuit through the auxiliary contacts of the isolating switch. However, it relies on the correctness of the contacts and cannot handle false alarms. Another example is a synchronous closing device disclosed in Chinese patent CN208015381U, which sets a synchronous check relay in the closing circuit and blocks unsuitable closing commands by comparing the phase difference of single-phase voltages. However, it only works before closing and only considers single-phase voltage, making it unable to monitor the actual system status after closing or identify "false grid connection" caused by mechanical failures of primary equipment. Therefore, there is an urgent need for a method that can effectively identify and quickly cut off the asynchronous state after the circuit breaker is closed, addressing the special abnormal condition of "false grid connection" caused by false alarms from the position contacts despite the isolating switch not being fully closed. Summary of the Invention

[0004] This application provides a method and system for grid-connected asynchronous protection under special abnormal operating conditions. It can accurately identify the "false grid connection" state caused by the disconnecting switch not being closed in a preset time window by real-time monitoring of the phasor difference of the six-phase voltage on both sides after the circuit breaker is closed, and by combining multiple criteria such as negative sequence voltage and voltage effective value. It can also quickly trip the circuit breaker before the fault develops into a catastrophic breakdown, effectively protecting the primary electrical equipment.

[0005] In a first aspect, embodiments of this application provide a method for grid-connected asynchronous protection under special abnormal operating conditions, comprising the following steps: Acquire the closing position signal of the circuit breaker at the synchronization point and the analog voltage on both sides of the circuit breaker, wherein the analog voltage includes the three-phase analog voltage on the generator side and the three-phase analog voltage on the grid side; If the closing position signal is detected to change from the opening position to the closing position, the grid connection asynchrony abnormality judgment is performed within the preset monitoring time window: the voltage phasor difference between the corresponding phases of the three-phase voltage on the generator side and the three-phase voltage on the grid side is calculated in real time based on the voltage analog quantity. If the absolute value of the three-phase voltage phasor difference is greater than the preset setting value and continues to reach the preset delay time, it is judged as a grid connection asynchrony abnormality. If the grid connection is determined to be out of sync, the grid connection out-of-sync protection action is executed; the grid connection out-of-sync protection action includes issuing a trip command to the circuit breaker.

[0006] In conjunction with the first aspect, in one implementation, the step of determining grid connection asynchrony anomalies within a preset monitoring time window, before performing the grid connection asynchrony anomaly determination, further includes: Calculate the negative sequence voltage on the generator side and the negative sequence voltage on the grid side based on the voltage analog quantity; Determine whether both the negative sequence voltage on the generator side and the negative sequence voltage on the grid side are less than the preset negative sequence voltage setting value; If the negative sequence voltage on either side is greater than or equal to the preset negative sequence voltage setting value, the grid-connected asynchronous abnormal state determination is blocked.

[0007] In conjunction with the first aspect, in one implementation, the step of determining grid connection asynchrony anomalies within a preset monitoring time window, before performing the grid connection asynchrony anomaly determination, further includes: Based on the voltage analog quantity, determine whether the three-phase voltage on the generator side and the three-phase voltage on the grid side are both greater than the preset effective voltage value; If the voltage of any phase on any side is less than or equal to the preset effective voltage value, the grid-connected asynchronous abnormal state determination is blocked.

[0008] In conjunction with the first aspect, in one implementation, the step of determining grid connection asynchrony anomalies within a preset monitoring time window, before performing the grid connection asynchrony anomaly determination, further includes: Obtain the engagement / disengagement status of the soft pressure plate and / or hard pressure plate used to control the grid-connected asynchronous abnormal state determination function; The grid connection asynchrony abnormality determination is performed only when the soft pressure plate and / or hard pressure plate are in the engaged state.

[0009] In conjunction with the first aspect, in one implementation, if the voltage analog quantity does not satisfy the condition that the absolute value of the three-phase voltage phasor difference is greater than the preset setting value after the preset monitoring time window expires, then the determination of the grid-connected asynchronous abnormal state is stopped.

[0010] In conjunction with the first aspect, in one embodiment, the synchronizing point circuit breaker is the generator terminal circuit breaker.

[0011] In conjunction with the first aspect, in one embodiment, the synchronizing point circuit breaker is the high-voltage side circuit breaker of the main transformer to which the generator is connected.

[0012] Secondly, embodiments of this application provide a system based on a grid-connected asynchronous protection method under special abnormal operating conditions, including: The data acquisition module is configured to acquire the closing position signal of the synchronous point circuit breaker and the analog voltage on both sides of the circuit breaker, wherein the analog voltage includes the three-phase analog voltage on the generator side and the three-phase analog voltage on the grid side. The processing module, connected to the data acquisition module, is configured to detect the closing position signal of the synchronizing point circuit breaker. If the closing position signal changes from the open position to the closed position, the grid-connected asynchronous abnormal state determination is performed within a preset monitoring time window. The voltage phasor difference between the corresponding phases of the three-phase voltage on the generator side and the three-phase voltage on the grid side is calculated in real time based on the voltage analog quantity. If the absolute value of the three-phase voltage phasor difference is greater than the preset setting value and continues to reach the preset delay time, the grid-connected asynchronous abnormal state is determined, and an instruction to execute the grid-connected asynchronous protection action is sent. An execution module, connected to a processing module, is configured to perform grid-connected asynchronous protection actions, including issuing a trip command to the circuit breaker.

[0013] Thirdly, embodiments of this application provide a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements a method for grid-connected asynchronous protection under special abnormal operating conditions.

[0014] The beneficial effects of the technical solutions provided in this application include: 1. By acquiring the analog voltage of the six phases on both sides of the circuit breaker at the synchronization point, and within the preset monitoring time window after the circuit breaker changes from open to closed, the voltage phasor difference of the corresponding phase is calculated in real time. This allows for the determination of whether there is an abnormal state of non-synchronous grid connection and the execution of tripping. This solves the technical problem in related technologies where the "false grid connection" state caused by the position contact false alarm due to the disconnecting switch not being closed in place cannot be identified and protected. It realizes continuous monitoring of the actual grid connection state of the system after the circuit breaker is closed, and can quickly disconnect the fault before it develops into a catastrophic breakdown. This effectively protects primary electrical equipment such as generators, circuit breakers, and disconnecting switches, and avoids equipment damage and power grid accidents caused by huge inrush currents and arc erosion.

[0015] 2. By setting the logic that the three-phase voltage phasor difference must exceed the set value and continue for a period of time before a judgment is made, misjudgment caused by transient fluctuations, single-phase interference and other factors is effectively avoided. At the same time, combined with the preset monitoring time window, protection is only put into operation during the risk period after grid connection to prevent false tripping caused by abnormal conditions such as PT disconnection during normal operation.

[0016] 3. By setting multiple preconditions such as negative sequence voltage, effective voltage value, and pressure plate status before judgment, the judgment is only allowed when the system is symmetrical, the voltage is normal, and the protection is activated. This effectively avoids misjudgments caused by asymmetrical faults, PT disconnection, measurement abnormalities, or human error, and further improves the accuracy and reliability of protection actions. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the main steps of the method of the present invention; Figure 2 This is a schematic diagram of a grid-connected asynchronous fault according to an embodiment of the present invention; Figure 3 This is a logic diagram for grid-connected asynchronous protection in an embodiment of the present invention; Figure 4 This is a diagram illustrating an application example of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0020] Example 1: This application provides a method for grid-connected asynchronous protection under special abnormal operating conditions, which can be applied to generator protection devices or transformer protection devices to identify the "false grid connection" state caused by the isolation switch not being closed in place but the position contact falsely reporting, and to quickly disconnect it before the fault worsens. Specifically, the design of this invention stems from an in-depth analysis and summary of a real-life power system accident with unusual operating conditions. Taking an actual accident involving Unit 12 of a large hydropower station as an example: During the unit's grid connection process, a malfunction in the isolating switch operating mechanism (auxiliary switch premature signaling, clutch disengagement) caused the isolating switch to be actually in the open state (break approximately 10mm), while the monitoring system falsely reported it as closed. After the circuit breaker was released from the interlock, it closed normally, and the system entered an abnormal state of "circuit breaker closed but main circuit actually open." A schematic diagram of the fault is shown below. Figure 2 As shown, this type of fault is relatively rare, but once it occurs, no generator protection system can immediately detect and isolate it. Other protection systems can only operate when the fault develops to the point where a large short-circuit current appears and burns out the equipment.

[0021] Therefore, this invention is designed to fill this protection blind spot. It can quickly cut off the abnormal operating condition of the equipment in the shortest time before the fault current rises and the equipment is damaged, thereby truly protecting primary electrical equipment such as generators, disconnect switches, and circuit breakers. The following combination Figure 1 and Figure 3 The specific implementation methods of the present invention will be described in detail below: This method mainly includes the following steps: S1. Obtain the closing position signal of the synchronous point circuit breaker and the analog voltage on both sides of the circuit breaker. The analog voltage includes the three-phase analog voltage on the generator side and the three-phase analog voltage on the grid side. Specifically, the closing position signal of the synchronous point circuit breaker (such as the generator terminal circuit breaker GCB or the main transformer high voltage side circuit breaker) is obtained through the switch quantity acquisition module of the relay protection device. At the same time, the analog quantity acquisition module obtains the analog voltage on both sides of the circuit breaker. The analog voltage quantities include the three-phase analog voltage quantities on the generator side and the three-phase analog voltage quantities on the grid side. Based on the above analog voltage quantities, the three-phase voltage on the generator side is obtained through sampling, analog-to-digital conversion, and voltage phasor calculation. , , and the three-phase voltage on the grid side , , ; Sampling, analog-to-digital conversion, and voltage phasor calculation are all well-known technologies in the field of relay protection. For specific implementation methods, please refer to relevant textbooks or existing products. They will not be elaborated here.

[0022] S2. If the closing position signal is detected to change from the opening position to the closing position, the grid connection asynchrony abnormal state judgment is performed within the preset monitoring time window: the voltage phasor difference between the corresponding phases of the three-phase voltage on the generator side and the three-phase voltage on the grid side is calculated in real time based on the voltage analog quantity. If the absolute value of the three-phase voltage phasor difference is greater than the preset setting value and continues to reach the preset delay time, it is judged as a grid connection asynchrony abnormal state. The circuit breaker monitors the closing position signal in real time. When the signal changes from the open position to the closed position, it is determined that the circuit breaker has completed the closing operation. At this time, the preset monitoring time window 0~ (In this embodiment, 300s is preferred, but the time can be set from 10s to 300s.) It is used to limit the effective period of grid-connected asynchronous protection. Within the monitoring time window, the grid-connected asynchronous abnormal state judgment function is active. If the time exceeds the monitoring time window, the grid-connected asynchronous abnormal state judgment function will automatically exit to avoid false operation due to other abnormalities (such as PT disconnection) during normal operation. The specific determination methods include: ①The three-phase voltage on the generator side obtained in step S1 , , and the three-phase voltage on the grid side , , The voltage phasor difference between the corresponding phases on the generator side and the grid side is calculated in real time. If the absolute value of the three-phase voltage phasor difference is greater than the preset setting value... If the preset delay time is reached continuously, it is determined to be an abnormal state of non-synchronous grid connection. Among them, the preset setting value The preferred setting is 3V (approximately 5% of the rated voltage), which can be flexibly adjusted according to actual engineering needs. The selection of this setting value should take into account factors such as the accuracy of the voltage transformer and the maximum allowable deviation during normal system operation to ensure the reliability and sensitivity of the protection. If the absolute values ​​of the three-phase voltage phasor differences are all greater than If the delay continues for a preset duration, it is determined to be an abnormal state of non-synchronous grid connection. It should be noted that the preset delay duration in this embodiment is preferably 0.5s, and its tuning mainly considers: Avoiding the closing transient: The voltage fluctuation at the moment of circuit breaker closing usually lasts for tens to hundreds of milliseconds. A 0.5-second delay can effectively avoid this period. Taking into account the development of the fault: Actual cases show that it takes about 2 to 3 seconds from closing the circuit to the gap breaking down. A 0.5-second delay can confirm the continuity of the fault and leave enough time for subsequent tripping. Preventing transient interference: Single-phase transient interference has a short duration, and a 0.5-second delay can ensure that the operation only takes effect when all three phases are continuously abnormal.

[0023] The delay parameter can be flexibly adjusted according to actual engineering needs. The 0.5s in this embodiment is only an example and not a limitation. By setting the logic that the three-phase voltage phasor difference exceeds the set value and the preset delay time is continuously used for judgment, the misjudgment caused by transient fluctuations, single-phase interference and other factors is effectively avoided. At the same time, combined with the preset monitoring time window, the protection is only put into operation during the risk period after grid connection to prevent false tripping caused by abnormal conditions such as PT disconnection during normal operation.

[0024] ② In addition, considering the potential interference factors such as asymmetrical faults, PT disconnection, and measurement circuit abnormalities in actual power systems, to prevent accidental triggering of grid-connected asynchronous protection under the above operating conditions, this embodiment uses a preset monitoring time window of 0~ Within the system, before determining the abnormal state of grid connection asynchrony, the following interlocking logic (anti-maloperation measures) is also included: 201. Negative sequence voltage blocking: To avoid misjudging grid-connection asynchrony due to voltage asymmetry caused by asymmetrical faults in the system (such as single-phase grounding or two-phase short circuit), the following conditions must be met before performing the above judgment: Calculate the negative sequence voltage on the generator side based on the voltage analog quantity from step S1. and the negative sequence voltage on the grid side ; judge and Are all values ​​less than the preset negative sequence voltage setting value? (In this embodiment, 4V is preferred, which is about 7% of the rated voltage. It can be flexibly adjusted according to the specific parameters and operating requirements of the protected system.) If the negative sequence voltage on either side is greater than or equal to If so, it is determined that there is an asymmetric fault in the system, and therefore the abnormal state of non-synchronous grid connection is blocked. S202, Voltage RMS value blocking: To avoid misjudgments due to measurement anomalies such as voltage transformer disconnection or undervoltage, the following conditions must be met before performing the above judgment: Based on the three-phase voltage on the generator side obtained in step S1 , , and the three-phase voltage on the grid side , , Determine whether all values ​​are greater than the preset effective voltage value. (In this embodiment, 52V is preferred, which is about 90% of the rated voltage. Its function is to confirm that the voltage transformer is working properly and the system voltage is normal, and to avoid misjudgment due to measurement abnormalities such as voltage transformer disconnection or undervoltage. This threshold value can be flexibly adjusted according to the actual engineering needs.) If the voltage of any phase on either side is less than or equal to If the voltage transformer or measurement circuit is abnormal, the non-synchronous grid connection abnormality judgment is blocked. S203, Pressure Plate Status Determination: To ensure that the protection function only takes effect when the operator explicitly activates it, and to avoid accidental activation due to misoperation or maintenance, the following conditions must be met before performing the above judgment: Obtain the activation / deactivation status of the soft and / or hard pressure plates used for determining grid-connected asynchronous abnormal states; Grid connection asynchrony abnormality judgment is only allowed when the soft pressure plate and / or hard pressure plate are in the working state.

[0025] S3. If the grid connection is determined to be out of sync, the grid connection out-of-sync protection action shall be executed; the grid connection out-of-sync protection action includes issuing a trip command to the circuit breaker.

[0026] Once a non-synchronous grid connection abnormality is detected, the relay will send a trip command to the synchronizing point circuit breaker to disconnect the circuit breaker, thereby isolating the generator from the power grid system and ensuring that the fault is quickly cleared before the isolating switch gap breaks down. By issuing tripping commands in a timely manner, this method can quickly clear the fault within a second-level time window before the isolating switch gap breaks down, preventing the fault from developing into a high-current short circuit and effectively protecting primary electrical equipment such as generators, circuit breakers, and disconnecting switches from damage caused by huge inrush currents and arc erosion.

[0027] like Figure 4 As shown, the present invention was successfully put into operation at the Wudongde Hydropower Station in December 2025 and applied to the PCS-985GW generator protection device of Nanjing NARI Relay Protection & Automation Co., Ltd. This application example proves the practicality and technical effect of the present invention.

[0028] Example 2: This application provides a system based on the method of embodiment one. This system can be integrated into a generator protection device or a transformer protection device to implement the grid-connected asynchronous protection method under special abnormal operating conditions in embodiment one. The system includes: The data acquisition module is configured to acquire the closing position signal of the synchronous circuit breaker and the analog voltage on both sides of the circuit breaker. The analog voltage includes the three-phase analog voltage on the generator side and the three-phase analog voltage on the grid side. In specific implementation, the module acquires the circuit breaker position signal through the switch input interface of the protection device and acquires the six voltage signals on the secondary side of the TV through the analog quantity acquisition circuit.

[0029] The processing module, connected to the data acquisition module, is configured to detect the closing position signal of the synchronizing point circuit breaker. If the closing position signal changes from the open position to the closed position, the grid-connected non-synchronous abnormal state judgment is performed within the preset monitoring time window: the voltage phasor difference between the corresponding phases of the three-phase voltage on the generator side and the three-phase voltage on the grid side is calculated in real time based on the voltage analog quantity. If the absolute value of the three-phase voltage phasor difference is greater than the preset setting value and continues to reach the preset delay time, the grid-connected non-synchronous abnormal state is judged, and an instruction to execute the grid-connected non-synchronous protection action is sent. In addition, the processing module also integrates the negative sequence voltage blocking, effective voltage value blocking, and pressure plate status determination logic from Embodiment 1 to prevent the grid-connected asynchronous protection from malfunctioning.

[0030] The execution module, which is connected to the processing module, is configured to perform grid-connected asynchronous protection actions, including issuing trip commands to the circuit breaker. This module achieves the trip output through the output relay of the protection device.

[0031] The specific workflow, parameter tuning, and logical judgment of each module in this system are the same as those in Embodiment 1, and will not be repeated here.

[0032] Example 3: This application provides a computer-readable storage medium storing a computer program thereon. When the computer program is executed by a processor, it implements the grid-connected asynchronous protection method under special abnormal operating conditions as described in embodiment one.

[0033] Specifically, the computer-readable storage medium can be a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, an optical disk, or any other medium capable of storing program code. When the computer program is executed by the processor, it can implement all the steps S1 to S3 in Embodiment 1, including: acquiring the circuit breaker closing position signal and the six-phase voltage analog quantity; detecting the closing event and starting a preset monitoring time window; performing grid-connection asynchrony abnormal state determination, as well as negative sequence voltage blocking, voltage effective value blocking, and pressure plate state determination, etc., within the preset monitoring time window; and issuing a trip command after determining that the grid-connection asynchrony abnormal state is abnormal.

[0034] The method details, parameter tuning, and logic flow implemented by this storage medium are the same as those in Embodiment 1, and will not be repeated here.

[0035] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0036] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0037] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for grid-connected asynchronous protection under special abnormal operating conditions, characterized in that, Includes the following steps: Acquire the closing position signal of the circuit breaker at the synchronization point and the analog voltage on both sides of the circuit breaker, wherein the analog voltage includes the three-phase analog voltage on the generator side and the three-phase analog voltage on the grid side; If the closing position signal is detected to change from the opening position to the closing position, the grid connection asynchrony abnormality judgment is performed within the preset monitoring time window: the voltage phasor difference between the corresponding phases of the three-phase voltage on the generator side and the three-phase voltage on the grid side is calculated in real time based on the voltage analog quantity. If the absolute value of the three-phase voltage phasor difference is greater than the preset setting value and continues to reach the preset delay time, it is judged as a grid connection asynchrony abnormality. If the grid connection is determined to be out of sync, the grid connection out-of-sync protection action is executed; the grid connection out-of-sync protection action includes issuing a trip command to the circuit breaker.

2. The grid-connected asynchronous protection method under special abnormal operating conditions according to claim 1, characterized in that, Within the preset monitoring time window, before performing the grid connection asynchrony anomaly determination, the process also includes: Calculate the negative sequence voltage on the generator side and the negative sequence voltage on the grid side based on the voltage analog quantity; Determine whether both the negative sequence voltage on the generator side and the negative sequence voltage on the grid side are less than the preset negative sequence voltage setting value; If the negative sequence voltage on either side is greater than or equal to the preset negative sequence voltage setting value, the grid-connected asynchronous abnormal state determination is blocked.

3. The grid-connected asynchronous protection method under special abnormal operating conditions according to claim 1, characterized in that, Within the preset monitoring time window, before performing the grid connection asynchrony anomaly determination, the process also includes: Based on the voltage analog quantity, determine whether the three-phase voltage on the generator side and the three-phase voltage on the grid side are both greater than the preset effective voltage value; If the voltage of any phase on any side is less than or equal to the preset effective voltage value, the grid-connected asynchronous abnormal state determination is blocked.

4. The grid-connected asynchronous protection method under special abnormal operating conditions according to claim 1, characterized in that, Within the preset monitoring time window, before performing the grid connection asynchrony anomaly determination, the process also includes: Obtain the engagement / disengagement status of the soft pressure plate and / or hard pressure plate used to control the grid-connected asynchronous abnormal state determination function; The grid connection asynchrony abnormality determination is performed only when the soft pressure plate and / or hard pressure plate are in the engaged state.

5. The grid-connected asynchronous protection method under special abnormal operating conditions according to claim 1, characterized in that, If, after the preset monitoring time window expires, the voltage analog quantity does not satisfy the condition that the absolute value of the three-phase voltage phasor difference is greater than the preset setting value, then the determination of the grid-connected asynchronous abnormal state will be stopped.

6. The grid-connected asynchronous protection method under special abnormal operating conditions according to claim 1, characterized in that, The synchronization point circuit breaker is the generator terminal circuit breaker.

7. The grid-connected asynchronous protection method under special abnormal operating conditions according to claim 1, characterized in that, The synchronizing circuit breaker is the high-voltage side circuit breaker of the main transformer connected to the generator.

8. A system based on the grid-connected asynchronous protection method under special abnormal operating conditions as described in claim 1, characterized in that, include: The data acquisition module is configured to acquire the closing position signal of the synchronous point circuit breaker and the analog voltage on both sides of the circuit breaker, wherein the analog voltage includes the three-phase analog voltage on the generator side and the three-phase analog voltage on the grid side. The processing module, connected to the data acquisition module, is configured to detect the closing position signal of the synchronizing point circuit breaker. If the closing position signal changes from the open position to the closed position, the grid-connected asynchronous abnormal state determination is performed within a preset monitoring time window. The voltage phasor difference between the corresponding phases of the three-phase voltage on the generator side and the three-phase voltage on the grid side is calculated in real time based on the voltage analog quantity. If the absolute value of the three-phase voltage phasor difference is greater than the preset setting value and continues to reach the preset delay time, the grid-connected asynchronous abnormal state is determined, and an instruction to execute the grid-connected asynchronous protection action is sent. An execution module, connected to a processing module, is configured to perform grid-connected asynchronous protection actions, including issuing a trip command to the circuit breaker.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the grid-connected asynchronous protection method under special abnormal operating conditions as described in claim 1.

Images