Wind turbine generator grid-connected contactor control method, system and terminal device

Abstract

This application provides a control method, system, and terminal equipment for a grid-connected contactor of a wind turbine, relating to the field of electrical control technology for wind turbines. The method includes, in response to a grid-connected contactor tripping command, continuously monitoring the actual open state of the main contacts of the contactor; if the main contacts are detected to be open within a preset time threshold, a blocking pulse command is sent to the converter; if the main contacts are not detected to be open within the preset time threshold, the grid-connected contactor tripping command is sent again, and monitoring of the main contacts' open state is restarted; if the main contacts are still not detected to be open during the second monitoring process within the preset time threshold, the control frame circuit breaker is opened, and the current grid-connected contactor tripping operation is terminated. This application mitigates multiple safety hazards such as contactor tripping under load, delayed fault identification, and overvoltage risks caused by adhesion, significantly improving the operational reliability and intrinsic safety level of the doubly-fed wind turbine grid-connected system.

Description

Technical Field

[0001] This application relates to the field of electrical control technology for wind turbine generators, and in particular to a method, system and terminal equipment for controlling a grid-connected contactor for a wind turbine generator. Background Technology

[0002] Doubly fed wind turbine grid-connected contactors are prone to mechanical aging and main contact adhesion during long-term operation. However, existing control logic does not monitor the actual action delay and state accuracy, still designing it based on an ideal switch model: the converter blocks the pulse simultaneously with issuing the disconnect command, causing the contactor to trip under generator excitation current, exacerbating the risk of contact arcing and adhesion. Furthermore, in fault protection, the frame circuit breaker and grid-connected contactor are often triggered to disconnect synchronously. Due to the difference in their mechanical response times (the contactor is usually faster than the frame circuit breaker), the grid-connected contactor actually undertakes the disconnection task under high-current faults, exceeding its designed disconnection capacity. Simultaneously, the lack of an online identification mechanism for grid-connected contactor adhesion poses safety risks such as DC bus overvoltage, repeated Crowbar / Chopper operation, and even hardware damage during shutdown or startup. Summary of the Invention

[0003] The purpose of this application is to provide a method, system, and terminal equipment for controlling the grid-connected contactor of a wind turbine, so as to alleviate the above-mentioned technical problems existing in the prior art.

[0004] In a first aspect, the present invention provides a method for controlling a grid-connected contactor of a wind turbine generator, comprising: In response to the tripping command of the grid-connected contactor, continuous monitoring of the actual disconnection status of the main contacts of the grid-connected contactor is initiated. If the main contact is detected to be open within the preset time threshold, a blocking pulse command is sent to the converter. If the main contact is not detected to be open within the preset time threshold, the grid-connected contactor tripping command is sent again, and the monitoring of the main contact open state is restarted. If the main contact is not detected to be open during the secondary monitoring process within the preset time threshold, the control frame circuit breaker will be opened, and the current grid-connected contactor tripping operation will be terminated.

[0005] In an optional implementation, in response to a grid-connected contactor tripping command, continuous monitoring of the actual open state of the main contacts of the grid-connected contactor is initiated, including: In response to the tripping command of the grid-connected contactor, the mechanical action characteristic parameters are dynamically adjusted according to the current cumulative operating time and historical number of operations of the grid-connected contactor; The time window for determining whether the main contact has opened is determined based on the adjusted mechanical motion characteristic parameters. Within the time window, the on / off signals of the auxiliary contacts of the grid-connected contactor and the main circuit current signal are continuously collected, and the actual disconnection time of the main contacts is identified based on the timing coordination relationship between the two, so as to continuously monitor the actual disconnection state of the main contacts.

[0006] In an optional implementation, if the main contact is detected to be open within a preset time threshold, a blocking pulse command is sent to the converter, including: If the main contact is detected to be open within the preset time threshold, continuously verify whether the main circuit current has decayed to below the zero current threshold. After confirming that the current decay is complete and remains stable, a blocking pulse command is sent to the converter to enable continuous monitoring of the actual open state of the main contacts to support the safe blocking of the converter.

[0007] In an optional implementation, if no main contact disconnection is detected within the preset time threshold, the grid-connected contactor tripping command is sent again, and monitoring of the main contact disconnection status is restarted, including: If the auxiliary normally closed contact is not detected to change from closed to open within a preset time threshold after the first trip command is issued, the grid-connected contactor trip command will be output to the grid-connected contactor control circuit again. While outputting the grid-connected contactor tripping command again, the monitoring timer is reset and the current sampling buffer is cleared, and the continuous acquisition and status identification of the auxiliary normally closed contact on / off signal is restarted.

[0008] In an optional implementation, if no main contact disconnection is detected during the secondary monitoring process within the preset time threshold, the control frame circuit breaker is opened, and the current grid-connected contactor tripping operation is terminated, including: When the secondary monitoring process is completed and it is still confirmed that the main contacts have not been disconnected, a disconnect command is sent to the control frame circuit breaker. If the main contact is not detected to be open during the secondary monitoring process within the preset time threshold, the control frame circuit breaker will be opened, and the current grid-connected contactor tripping operation will be terminated.

[0009] In an optional implementation, in response to a grid-connected contactor tripping command, continuous monitoring of the actual open state of the main contacts of the grid-connected contactor is initiated, further including: When the wind turbine control system detects a serious fault, it suspends the execution of the grid-connected contactor tripping command and instead sends a disconnect command to the frame circuit breaker. After detecting that the main contacts of the frame circuit breaker are open, a tripping command is sent to the grid-connected contactor, and continuous monitoring of the actual open state of the main contacts is started simultaneously.

[0010] In an optional implementation, the method further includes: When the wind turbine is in standby mode, the main circuit voltage signal and auxiliary contact status signal of the grid-connected contactor are continuously collected. If a continuous voltage is detected in the main circuit and the auxiliary contact is in the closed state when the frame circuit breaker is in the open state, it is determined that the main contact of the grid-connected contactor is stuck, and the closing command to the frame circuit breaker is prohibited. At the same time, a grid-connected contactor sticking fault alarm is generated. When the wind turbine is in the shutdown process and the generator speed reaches the off-grid speed threshold, a grid-connected contactor tripping command is issued, and the main contact disconnection status monitoring is initiated. If the main contact disconnection is not detected within the preset time threshold, a secondary tripping and frame circuit breaker linkage disconnection operation is performed to achieve start-stop safety protection supported by continuous monitoring of the actual disconnection status of the main contact.

[0011] Secondly, the present invention provides a grid-connected contactor control system for wind turbine generators, comprising: The tripping command response unit is used to respond to the tripping command of the grid-connected contactor and start continuous monitoring of the actual disconnection status of the main contacts of the grid-connected contactor. The first disconnection judgment unit is used to send a blocking pulse command to the converter if the main contact is detected to be disconnected within a preset time threshold. The retransmission and re-monitoring unit is used to resend the grid-connected contactor tripping command and restart the monitoring of the main contact disconnection status if the main contact is not detected to be open within the preset time threshold. The over-level protection execution unit is used to control the circuit breaker to open and terminate the current grid-connected contactor tripping operation if the main contact is not detected to be open during the secondary monitoring process of the preset time threshold.

[0012] Thirdly, the present invention provides a terminal device, which is an embedded edge execution device deployed in a converter cabinet and directly connected in series between the contactor / circuit breaker drive circuit and the main control system, for implementing the wind turbine grid-connected contactor control method described in any of the foregoing embodiments.

[0013] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions, which, when invoked and executed by a processor, cause the processor to implement the wind turbine grid-connected contactor control method described in any of the foregoing embodiments.

[0014] The wind turbine grid-connected contactor control method, system, and terminal equipment provided in this application immediately initiate continuous monitoring of the actual open state of the main contacts upon receiving a tripping command. This allows the system to break free from reliance on the ideal operating characteristics of the contactor and achieve closed-loop control based on the actual physical state. Only when the main contacts are reliably disconnected within a preset time threshold can the system issue a pulse blocking command, ensuring that the converter only disconnects the excitation circuit after the contactor has completely left the current path. This effectively avoids the risks of arcing and contact sticking caused by on-load tripping. If no contact disconnection is detected, the system executes a secondary tripping command and re-monitors the state to improve fault tolerance for intermittent signal loss or mechanical jamming. If the secondary operation still fails, the frame circuit breaker is immediately triggered to trip and subsequent operations are terminated. This serves as a safety fallback mechanism to prevent the stuck contactor from continuously bearing rotor induced voltage, which could lead to cascading faults such as DC bus overvoltage and Crowbar overheating damage. The aforementioned hierarchical and progressive control logic systematically mitigates multiple safety hazards, such as contactor tripping under load, delayed fault identification, and overvoltage risks caused by adhesion, significantly improving the operational reliability and intrinsic safety level of the doubly-fed wind turbine grid-connected system. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 A flowchart of a wind turbine grid-connected contactor control method provided in this application embodiment; Figure 2 A flowchart for monitoring contact adhesion of grid-connected contactors in standby mode of a wind turbine generator is provided in an embodiment of this application. Figure 3 A flowchart of a wind turbine grid disconnection control provided in this application embodiment; Figure 4 This is a structural diagram of a wind turbine grid-connected contactor control system provided in an embodiment of this application. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0019] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0020] This application provides a method for controlling a grid-connected contactor for a wind turbine generator. (See also...) Figure 1 As shown, the method mainly includes the following steps: S110, in response to the tripping command of the grid-connected contactor, initiates continuous monitoring of the actual disconnection status of the main contacts of the grid-connected contactor.

[0021] In one implementation, the aforementioned grid-connected contactor tripping command is initiated by the wind turbine control system when the off-grid speed is reached. When the converter control system receives this command, the control monitoring module starts continuous monitoring of the actual open state of the main contacts of the grid-connected contactor. Continuous monitoring of the actual open state of the main contacts of the grid-connected contactor can be determined by continuously sampling and identifying the on / off signals of the auxiliary normally closed contacts of the grid-connected contactor. By continuously collecting the on / off signals of the auxiliary normally closed contacts of the grid-connected contactor, when it is detected that the auxiliary normally closed contact has changed from a closed state to an open state and remains stable, it is determined that the main contacts have actually opened.

[0022] S120: If the main contact is detected to be open within a preset time threshold, a blocking pulse command is sent to the converter.

[0023] In one example, the aforementioned preset time threshold can be set to 200ms. In practical applications, this value is based on the mechanical action time of the grid-connected contactor. When the auxiliary normally closed contact is detected to change from closed to open within the preset time threshold and maintain this open state, the converter control system issues a command to block the IGBT drive pulse to the generator-side and grid-side converters.

[0024] S130: If the main contact is not detected to be open within the preset time threshold, the grid-connected contactor tripping command is sent again, and the monitoring of the main contact open status is restarted.

[0025] In practice, if the auxiliary normally closed contact is not detected to be open within the preset time threshold, the converter control system will output the tripping drive signal to the grid-connected contactor control circuit again, and simultaneously reset the monitoring timer, clear the sampling buffer, and restart the continuous sampling and status identification of the auxiliary normally closed contact on / off signal.

[0026] S140 If the main contact is not detected to be open during the secondary monitoring process within the preset time threshold, the control frame circuit breaker will be opened, and the current grid-connected contactor tripping operation will be terminated.

[0027] If the auxiliary normally closed contact fails to open during the monitoring of the preset time threshold during the second startup, the converter control system outputs a tripping drive signal to the tripping coil of the frame circuit breaker to disconnect the main circuit; at the same time, it prohibits all subsequent tripping commands for the grid-connected contactor and enters the fault shutdown process.

[0028] This application upgrades the tripping control of the grid-connected contactor from the traditional open-loop command-based system to a closed-loop state monitoring mechanism based on auxiliary contact feedback, ensuring that the control system can accurately respond to the actual physical actions of the main contacts. The system completes the initial state determination and secondary retry within a preset time window, taking into account both the mechanical response characteristics of the contactor and the fault tolerance requirements under abnormal signal conditions. A pulse blocking logic based on confirmation of the actual disconnection state of the main contacts is adopted, replacing the original control method of blocking upon command issuance, fundamentally eliminating the risk of contact sticking caused by tripping with excitation current. Simultaneously, a timing strategy for prior tripping of the frame circuit breaker is constructed, and in the event of a sticking fault, the frame circuit breaker is forcibly tripped and the system shut down, preventing it from bearing large fault currents or continuously carrying rotor induced voltage, thereby preventing serious accidents such as DC bus overvoltage, repeated operation of the Crowbar and Chopper, damage to power devices, and even fire and tower collapse. Overall, this solution significantly improves the operational reliability, fault robustness, and intrinsic safety level of the doubly-fed wind turbine grid-connected system.

[0029] For ease of understanding, the specific implementation methods of the above-mentioned methods provided in this application will be described in detail below.

[0030] In one implementation, the above-mentioned continuous monitoring of the actual open state of the main contacts of the grid-connected contactor in response to the grid-connected contactor tripping command may include the following steps 1.1 to 1.3: Step 1.1: In response to the tripping command of the grid-connected contactor, dynamically adjust the mechanical action characteristic parameters based on the current cumulative operating time and historical number of actions of the grid-connected contactor.

[0031] The service status of the grid-connected contactor is used as the input for adaptive control parameters. By linking its physical aging degree in real time (using cumulative operating time to represent the deterioration trend and historical number of actions to represent the accumulation of mechanical wear), the core parameters affecting the tripping response characteristics are corrected online, thereby overcoming the problem of poor adaptability of fixed delay criteria throughout the entire life cycle of the device. Among them, the mechanical action characteristic parameters specifically refer to the time characteristic quantities used to describe the entire process of the grid-connected contactor from receiving the command to the main contact completing the separation, including but not limited to typical tripping delay, dispersion range, response attenuation coefficient, etc. The adjustment results directly determine the setting accuracy of the subsequent time window.

[0032] In practical implementation, each time the wind turbine control system receives a grid-connected contactor tripping command, it reads two operating parameters stored in the local non-volatile memory: one is the cumulative operating time of the grid-connected contactor (in hours), which is accumulated and synchronously updated by the main control system; the other is the total number of historical actions of the grid-connected contactor (in times), which is recorded by the converter program. The controller queries the tripping delay correction coefficient under the corresponding combination of duration and number of actions based on a preset aging mapping table (this table is calibrated based on accelerated life test data of the same model of contactor, and only contains table lookup logic, not calculation formulas). The controller then applies this coefficient to the basic mechanical action parameters (such as the factory-nominated tripping time) to generate the dynamically adjusted parameters used for this tripping. This process does not involve real-time modeling or online identification, but is achieved only through table lookup and linear scaling, ensuring determinism and timeliness in execution.

[0033] Step 1.2: Determine the time window for judging whether the main contact is disconnected based on the adjusted mechanical action characteristic parameters.

[0034] The dynamically adjusted mechanical action characteristic parameters are directly converted into executable monitoring time boundaries. That is, a time window covering more than 99% of the normal operation probability is set with the corrected average opening delay as the center and combined with its statistical dispersion upper limit. This window serves as the effective time limit for determining the main contact disconnection state. This window avoids false alarms and failure to operate due to parameter solidification and also prevents delays in fault intervention due to an excessively wide window. It is a key bridge connecting aging perception and real-time judgment.

[0035] In practice, the controller substitutes the dynamically adjusted parameters output in step 1.1—including the corrected typical tripping delay value and its maximum allowable deviation value—into a preset window generation rule: the start time of the time window is the time when the tripping command is issued, and the end time is the time point corresponding to the corrected typical tripping delay value plus the corrected maximum deviation value. This time point is converted by the system clock and written to the hardware timer as a timeout threshold. The entire process does not rely on external communication or manual configuration; the controller completes parameter parsing and threshold loading locally, ensuring that the time window strictly matches the current device state.

[0036] Step 1.3: Within the time window, continuously collect the on / off signals of the auxiliary contacts of the grid-connected contactor and the main circuit current signal, and identify the actual disconnection time of the main contacts based on the timing coordination relationship between the two, and continuously monitor the actual disconnection state of the main contacts.

[0037] A dual-signal timing collaborative verification mechanism is adopted to improve the confidence of state recognition. The auxiliary contact on / off signal reflects the action result of the mechanical linkage mechanism, while the main circuit current signal reflects the energy path change caused by the physical on / off of the main contact. The two have a deterministic sequential relationship during normal tripping (the auxiliary contact opens before or simultaneously with the main contact, and the main circuit current lags behind the auxiliary contact opening). By verifying whether this timing relationship meets expectations, misjudgments caused by interference, sticking, or feedback distortion of a single signal can be effectively filtered out, achieving highly reliable capture of the actual opening moment of the main contact.

[0038] In practical implementation, after the time window opens, the controller synchronously acquires two signals at a frequency of not less than 2kHz: one is the switching level signal of the auxiliary normally closed contact of the grid-connected contactor (input via optocoupler isolation), and the other is the analog signal output by the main circuit current sensor (such as a Hall current sensor) (converted by an ADC); the controller detects the transition edge of the auxiliary contact level from high (closed) to low (open) in real time and records the occurrence time T1; then it detects whether the amplitude of the main circuit current drops below 5% of the rated current within a specified short delay (e.g., 5ms) after T1, and maintains this state for at least 10ms. If this is satisfied, the time T2 when the main circuit current returns to zero is recorded; when T1 and T2 satisfy T2>T1 and T2 When T1 ≤ the preset reasonable delay limit (e.g., 20ms), the "actual disconnection time of the main contact" is determined to be T2, and this completes the "continuous monitoring of the actual disconnection status of the main contact".

[0039] The above method uses the cumulative operating time and historical number of actions of the grid-connected contactor as the basis for dynamic parameter adjustment, so that the time window can adaptively shrink or extend as the device ages, fundamentally solving the sensitivity mismatch problem of fixed delay criteria under long service cycles. Furthermore, by verifying the timing of auxiliary contact signals and main circuit current signals, the anti-interference capability and physical authenticity of the main contact disconnection status identification are significantly improved without increasing the number of sensors, effectively avoiding the risk of misjudgment caused by auxiliary contact false alarms, main contact micro-arc adhesion, or current sampling drift.

[0040] Furthermore, if the main contact is detected to be open within a preset time threshold, a blocking pulse command is sent to the converter. In specific implementation, this may include the following steps 2.1 and 2.2: Step 2.1: If the main contact is detected to be open within the preset time threshold, continuously verify whether the main circuit current has decayed to below the zero current threshold.

[0041] When continuously verifying whether the open state of the auxiliary normally closed contact remains stable, the auxiliary normally closed contact signal can be continuously sampled. After the signal transitions from closed to open, it remains open within a set debouncing time to eliminate transient misjudgments caused by mechanical vibration or electrical contact bounce. For example, the auxiliary normally closed contact level signal can be acquired at a frequency of at least 1kHz. When the signal is detected to transition from high level (closed) to low level (open), a 10ms timing window is started, and the signal is continuously read within this window. Only when all sampled values ​​are low is it determined that the main contact is truly open.

[0042] Step 2.2: After confirming that the current decay is complete and remains stable, a blocking pulse command is sent to the converter to enable continuous monitoring of the actual open state of the main contacts to support the safe blocking of the converter.

[0043] In one example, confirming that the auxiliary normally closed contact is in a stable open state completes the 10ms debouncing verification process described in step 2.1. In a specific implementation, when the 10ms debouncing window ends and the auxiliary normally closed contact signal remains open, the converter control module is immediately triggered to output a blocking command, causing the generator-side and grid-side converters to synchronously stop the IGBT drive pulse output.

[0044] The above method uses the cumulative running time and historical number of actions of the grid-connected contactor as the basis for dynamic parameter adjustment, so that the time window can be adaptively adjusted as the device ages, fundamentally solving the problem of sensitivity mismatch of fixed delay criteria throughout the entire life cycle. At the same time, the timing collaborative verification mechanism of auxiliary contact signal and main circuit current signal is adopted, which significantly improves the anti-interference capability and physical authenticity of main contact disconnection status identification without increasing sensor cost, and effectively avoids the risk of misjudgment caused by auxiliary contact false alarm, main contact micro-arc adhesion or current sampling drift.

[0045] Furthermore, if no main contact disconnection is detected within the preset time threshold, the grid-connected contactor tripping command is sent again, and the monitoring of the main contact disconnection status is restarted. In specific implementation, this may include the following steps 3.1 and 3.2: Step 3.1: After the initial tripping command is issued, if the auxiliary normally closed contact is not detected to change from closed to open within the preset time threshold, the grid-connected contactor tripping command is output to the grid-connected contactor control circuit again.

[0046] The transition of the aforementioned auxiliary normally closed contact from closed to open is the most reliable and easily acquired mechanical linkage feedback signal during the normal tripping process of the grid-connected contactor. Its action sequence is deterministically correlated with the separation of the main contacts, and its anti-interference capability is superior to indirect measurement methods using pure voltage or current. This criterion effectively avoids the technical difficulties of directly detecting the insulation withstand voltage or arc state of the main contacts, achieving high-confidence state identification based on existing hardware.

[0047] In practice, when the controller sends the first tripping command to the grid-connected contactor control circuit, it starts a preset time threshold timing and continuously samples the switching signal of the auxiliary normally closed contact at a frequency of not less than 1kHz. If the signal is detected to remain high (corresponding to the closed state of the contact) during the timing period without a valid transition to low (corresponding to the open state of the contact), and the duration of this state reaches the upper limit of the preset time threshold, the controller determines that the auxiliary normally closed contact is not responding and then outputs a standard tripping command to the same grid-connected contactor control circuit again.

[0048] Step 3.2: While outputting the grid-connected contactor tripping command again, reset the monitoring timer and clear the current sampling buffer, and restart the continuous acquisition and status identification of the auxiliary normally closed contact on / off signal.

[0049] Within the same control cycle following the issuance of the second command, the control system completes a deterministic reset of the monitoring system and an upgrade of the data dimensions. By resetting the timer and clearing the buffer, it ensures that the new round of monitoring is unaffected by noise from previous sampling or buffer residue. By synchronously recording the coil drive voltage and the auxiliary contact response delay, the monitoring process, originally used only for real-time discrimination, is expanded into a data acquisition process that supports root cause analysis of faults. The auxiliary contact response delay specifically refers to the time interval from the rising edge of the coil drive voltage to the flipping of the auxiliary normally closed contact level; its changing trend can comprehensively reflect the coordinated degradation of the electromagnetic system's responsiveness and the mechanical transmission mechanism's flexibility.

[0050] In practical implementation, within the same control cycle of outputting the secondary tripping command, the controller performs the following three deterministic operations: First, it resets and restarts the preset time threshold monitoring timer; then, it clears the historical sampling sequence buffer of the auxiliary normally closed contact, the instantaneous value cache of the main circuit current, and the intermediate variables from the previous round of delay calculation; finally, it starts a new round of continuous acquisition. The new round of acquisition is triggered by a synchronous clock, simultaneously acquiring the voltage signal across the grid-connected contactor coil and the level signal of the auxiliary normally closed contact, and marking each sampling point with a precise timestamp. The controller calculates in real time the time difference between the rising edge of the current drive voltage and the flipping edge of the auxiliary contact level, storing this as the auxiliary contact response delay for the current cycle in the diagnostic log. All of the above operations serve the continuous monitoring of the actual open state of the main contacts; the recorded data is only used for subsequent offline analysis or long-term trend early warning and does not affect the real-time control logic.

[0051] This implementation uses the transition of the auxiliary normally closed contact state as the sole trigger condition for secondary tripping, and simultaneously starts the monitoring system reset and multi-parameter data acquisition upon command retransmission. This ensures rapid response to mechanical failures of the grid-connected contactor while avoiding the risk of misjudgment due to buffer contamination or accumulated timing errors. The synchronously recorded coil drive voltage and auxiliary contact response delay provide a complete chain of evidence for identifying typical aging modes such as abnormal coil power supply, contact spring fatigue, and armature jamming, making continuous monitoring of the actual open state of the main contacts traceable in engineering. This solution fully reuses the existing sensor configuration of the wind turbine unit. The auxiliary contact and coil voltage sampling points are all standard interfaces of the doubly-fed generator unit, requiring no additional hardware, yet significantly improving the early detection rate and handling accuracy of contactor-level faults, effectively supporting the technical goals of improving the operational stability and extending the service life of grid-connected contactors.

[0052] Furthermore, if the main contact is not detected to be open during the secondary monitoring process within the preset time threshold, the control frame circuit breaker will open, and the current grid-connected contactor tripping operation will be terminated. In specific implementation, this may include the following steps 4.1 and 4.2: Step 4.1: After the secondary monitoring process is completed and it is still confirmed that the main contacts have not been disconnected, a disconnect command is sent to the control frame circuit breaker.

[0053] After secondary monitoring fails, the system will trigger the frame circuit breaker to force intervention as a clear protection criterion. When the grid-connected contactor fails to physically separate its main contacts within the corresponding preset time thresholds after the initial trip command and subsequent secondary trip commands are issued, the control system will not execute a third drive attempt, but will immediately activate the next-level protection device, namely the frame circuit breaker, to perform a hard disconnection of the main circuit, thus achieving the final blocking of the fault current path. The secondary monitoring process includes the first preset time threshold monitoring initiated after the initial trip command is issued, and the second independent preset time threshold monitoring initiated after the secondary trip command is issued. The logic and sampling method of the two monitoring are completely consistent.

[0054] In practice, after the controller outputs the second tripping command, it immediately restarts the main contact status monitoring timer and continuously reads the auxiliary contact signal of the grid-connected contactor, the main circuit current signal, and the voltage change trend. If, at the end of the preset time threshold, none of the monitoring channels output a confirmation that the main contacts have been opened (i.e., the auxiliary contacts are still closed, the main circuit current has not returned to zero, and the voltage at both ends of the main circuit has not dropped to the residual voltage level), the controller determines that the secondary monitoring has failed and then outputs a tripping command to the operating mechanism drive circuit of the frame circuit breaker to initiate its mechanical tripping action.

[0055] Step 4.2: If the main contact is not detected to be open during the secondary monitoring process of the preset time threshold, the control frame circuit breaker is opened and the current grid-connected contactor tripping operation is terminated.

[0056] After the main circuit is successfully disconnected by the frame circuit breaker, the system further performs electrical cascade isolation and fault state solidification. By cutting off the power supply to the grid-connected contactor control circuit, the possibility of accidental triggering is completely eliminated, and the failure event is marked as an unrecoverable permanent fault in the form of a software flag. This supports subsequent maintenance diagnosis, automatic locking, and human-machine interaction alarms and other fault isolation operations. The permanent fault flag is a read-only fault latch bit set internally by the control system. Once set, it can only be cleared after manual reset or offline maintenance confirmation to prevent automatic restart from causing the risk to recur.

[0057] In practice, after issuing the tripping command to the frame circuit breaker, the controller continuously samples the feedback signal of its auxiliary contact disconnection. When the signal is detected to have remained stably disconnected for more than the confirmation time, it is determined that the main contacts of the frame circuit breaker have reliably disconnected. At this time, the controller immediately shuts off the power output of the grid-connected contactor control circuit, completely isolating the grid-connected contactor from the influence of the control signal. Simultaneously, the permanent fault flag of the grid-connected contactor is set to an active state in the system fault register, and the flag is simultaneously uploaded to the main control system and remote monitoring platform. The human-machine interface displays a message indicating that the grid-connected contactor has hardware failure and requests a shutdown for inspection, and prohibits any operation commands from being issued to the contactor in any subsequent startup process.

[0058] The above approach constructs a complete closed-loop safety link from status identification, hardware intervention, electrical isolation to fault solidification by implementing three measures in conjunction with the secondary monitoring failure: tripping the frame circuit breaker, cutting off the grid-connected contactor control power supply, and setting a permanent fault flag. This mechanism ensures reliable power disconnection of the main circuit in the event of complete grid-connected contactor failure, avoiding cascading risks such as repeated Crowbar and Chopper actions, DC bus overvoltage, and thermal breakdown of power devices caused by a continuous rise in rotor induced voltage. Furthermore, by cutting off the control circuit power and setting a permanent fault flag, it fundamentally eliminates the possibility of contactor operation with faults caused by program misjudgment, signal interference, or automatic retries, providing a clear and unavoidable hard shutdown basis for on-site maintenance, and significantly improving the intrinsic safety level and maintainability of the doubly-fed wind turbine in the event of failure of critical actuators.

[0059] Furthermore, the above-mentioned response to the grid-connected contactor tripping command, which initiates continuous monitoring of the actual open state of the main contacts of the grid-connected contactor, also includes the following steps 5.1 and 5.2: Step 5.1: When the wind turbine control system detects a serious fault, it suspends the execution of the grid-connected contactor tripping command and instead sends a disconnect command to the frame circuit breaker.

[0060] Under the fault classification management framework, severe faults are used as the trigger condition for control logic jumps. This proactively interrupts the conventional path of directly driving the grid-connected contactor to trip from the converter, instead prioritizing the activation of the frame circuit breaker, which has a slower response speed but a larger breaking capacity, to handle the initial high-current interruption task. Severe faults include short-circuit faults, hardware overcurrent faults, stator contactor faults, frame circuit breaker faults, hardware overvoltage faults, and grounding faults. These types of faults are characterized by high current rise rate, large amplitude, and concentrated energy. If the conventional process is followed, and the faster-acting but limited-breaking-capacity grid-connected contactor is the first to be affected, it can easily lead to arc erosion, welding, or even explosion of its main contacts.

[0061] In practice, the wind turbine control system receives multi-source fault signals from the converter protection module, main control system, and electrical protection unit in real time, and classifies and judges them according to the preset fault level mapping table. Once any serious fault flag bit is set, such as a short circuit fault or hardware overcurrent fault flag bit being 1, the controller immediately clears the grid-connected contactor tripping command cache written to the output register, and simultaneously sends a high-level valid tripping command to the operating mechanism drive circuit of the frame circuit breaker. At the same time, it starts the frame circuit breaker main contact status monitoring timer and enters the waiting and judgment process in step 5.2.

[0062] Step 5.2: After detecting that the main contact of the frame circuit breaker is open, send a trip command to the grid-connected contactor and simultaneously start continuous monitoring of the actual open state of the main contact.

[0063] Based on the actual disconnection of the main contacts of the frame circuit breaker, a two-stage disconnection timing dependency is constructed to ensure that the grid-connected contactor can only perform a tripping action after the main circuit current has been effectively interrupted by the frame circuit breaker, thereby completely avoiding the risk of tripping with a large fault current. Specifically, detecting the disconnection of the frame circuit breaker's main contacts refers to confirming the physical contact separation through its position feedback signal, such as the output of a limit switch, auxiliary contacts, or Hall sensor, rather than solely relying on whether a control command has been issued.

[0064] In practical implementation, after issuing the trip command to the frame circuit breaker, the controller continuously samples the open status signal of its auxiliary contacts. When this signal stably maintains the open state for more than a set confirmation time, it is determined that the main contacts of the frame circuit breaker have reliably opened. At this time, the controller immediately outputs a trip command to the grid-connected contactor control circuit and simultaneously starts continuous monitoring of the actual open status of the aforementioned main contacts, that is, reading the feedback from the auxiliary contacts of the grid-connected contactor, sampling the trend of current and voltage changes in the main circuit, and completing the closed-loop verification of whether the main contacts are truly separated within a preset time threshold.

[0065] The above method reconstructs the tripping control timing under severe fault scenarios, adjusting the operation of the frame circuit breaker from parallel with the grid-connected contactor to priority operation and first disconnection. It uses the measured open state of the main contacts as the enabling condition for the grid-connected contactor's operation, fundamentally eliminating the risks of contact adhesion, arcing failure, and cascading damage caused by the grid-connected contactor's forced disconnection under large short-circuit current conditions. Simultaneously, this hierarchical coordination mechanism does not increase system hardware complexity; it achieves functional decoupling of key components and improved safety margins solely through control logic reconstruction and state feedback closed-loop, significantly enhancing the passive protection capability and operational robustness of the doubly-fed induction generator (DFIG) under extreme electrical faults. This provides underlying control assurance for meeting grid fault ride-through requirements and improving the overall safety level of the generator.

[0066] Furthermore, to avoid the risk of DC bus overvoltage breakdown during startup due to main contact adhesion, and to prevent major safety accidents such as hardware damage, fire, or even tower collapse caused by prolonged operation of the Crowbar and Chopper, heat accumulation in power devices, and uncontrolled rise in DC bus voltage during shutdown due to main contact failure, the above methods also include: Step 6.1: When the wind turbine is in standby mode, continuously collect the main circuit voltage signal and auxiliary contact status signal of the grid-connected contactor; if a continuous voltage is detected in the main circuit and the auxiliary contact is in the closed state when the frame circuit breaker is in the open state, it is determined that the main contact of the grid-connected contactor is stuck, and the closing command to the frame circuit breaker is prohibited. At the same time, a grid-connected contactor sticking fault alarm is generated.

[0067] Assuming the physical disconnection state of the frame circuit breaker is a prerequisite, the actual on / off state of the main contacts of the grid-connected contactor is indirectly determined by synchronously monitoring the combined logic relationship between the main circuit voltage signal and the auxiliary contact status signal. Specifically, a continuous voltage in the main circuit indicates that even after the frame circuit breaker has been confirmed to be disconnected, a stable potential difference is still detected between the input and output terminals of the grid-connected contactor, indicating that the current path has not been interrupted. A closed auxiliary contact indicates that the feedback signal from its mechanically linked normally open or normally closed auxiliary contact shows a conducting state, reflecting that the control circuit command has been issued and the auxiliary mechanism has acted accordingly. When both conditions are met simultaneously, interference such as false control signal transmission and false auxiliary contact alarms can be ruled out, and the only reasonable inference is that the main contacts have physically adhered due to aging or welding.

[0068] In practical implementation, the converter control system initiates periodic sampling after the wind turbine enters standby mode. On one hand, it acquires the voltage difference between the input and output sides of the main contacts in real time through voltage sensors at both ends of the grid-connected contactor's main circuit, and sets voltage amplitude and duration thresholds as criteria for determining the presence of continuous voltage. On the other hand, it reads the switching signals of the auxiliary contacts built into the grid-connected contactor to confirm that their feedback state is closed. Simultaneously, the system continuously verifies the position feedback signal of the frame circuit breaker to ensure it is in a clearly open state. When all three conditions—frame circuit breaker open, main circuit voltage continuously exceeding the limit, and auxiliary contacts closed—are met within the same sampling period, the controller immediately blocks all subsequent closing commands sent to the frame circuit breaker and triggers a grid-connected contactor main contact adhesion fault alarm in the human-machine interface and background log, simultaneously marking this fault as a non-automatic reset fault.

[0069] Step 6.2: When the wind turbine is in the shutdown process and the generator speed reaches the off-grid speed threshold, issue a grid-connected contactor tripping command and start monitoring of the main contact disconnection status; if the main contact disconnection is not detected within the preset time threshold, perform secondary tripping and frame circuit breaker linkage disconnection operation to achieve start-stop safety protection supported by continuous monitoring of the actual disconnection status of the main contact.

[0070] The grid disconnection speed threshold is used as the physical criterion for triggering the tripping command, and a closed-loop control mechanism of "one command - status monitoring - timeout response - escalation handling" is constructed with a preset time threshold as the monitoring window. The grid disconnection speed threshold refers to the critical speed point at which the doubly-fed generator transitions from grid-connected operation to asynchronous operation, typically set within ±5% of the synchronous speed. At this speed, the electrical connection between the stator and the grid must be promptly disconnected to prevent the rotor induced voltage from continuously rising. The preset time threshold is a time tolerance set based on the typical mechanical tripping time of the grid-connected contactor, including the entire process of coil response, armature movement, and contact separation, plus a safety margin. It is used to determine whether a substantial failure of the main contacts to disconnect has occurred.

[0071] In practice, the converter control system tracks the generator speed signal in real time, which can come from the encoder or resolver decoding module. When the speed drops to a preset off-grid speed threshold, the system immediately outputs a trip command to the grid-connected contactor control circuit and simultaneously starts the main contact status monitoring timer. Monitoring methods include continuously reading the auxiliary contact disconnection feedback signal, synchronously sampling the main circuit current, and making a comprehensive judgment based on the main circuit voltage change trend. If, before the preset time threshold ends, any valid monitoring channel fails to confirm that the main contact has disconnected (i.e., the auxiliary contact is still closed, there is still current in the main circuit, or the main circuit voltage has not recovered to the residual voltage level), the controller executes a second trip command, outputs a pulse again, or extends the drive time, and continues monitoring after the second command is issued. If, after the second command is issued, disconnection is still not confirmed within the same preset time threshold, the controller immediately sends a trip command to the frame circuit breaker, forcibly cutting off the main circuit power supply and triggering a grid-connected contactor failure to operate fault alarm, entering the fault shutdown process.

[0072] At the same time, the solution also improves the accuracy of fault classification and the robustness of control timing, significantly extends the mechanical life of grid-connected contactors, and provides quantifiable and traceable status criteria support for the full life cycle reliability management of wind turbine units.

[0073] During the tripping process of the grid-connected contactor, the converter no longer synchronously blocks the pulse with the tripping command. Instead, it monitors the actual disconnection status of the main contacts of the grid-connected contactor in real time. Only after confirming that the main contacts have reliably disconnected is the pulse blocking operation executed. This timing control strategy fully considers the mechanical action time of the grid-connected contactor, ensuring that the contactor completes the tripping process under no-excitation current conditions, effectively reducing the risk of contact sticking.

[0074] Wind turbine faults are classified into general faults and serious faults. General faults include main circuit faults, external faults, stator contactor faults, frame circuit breaker faults, software version errors, and NTC temperature measuring resistor faults. Serious faults include stator software overcurrent faults, rotor software overcurrent faults, short circuit faults, hardware overcurrent faults, hardware overvoltage faults, and grounding faults.

[0075] For severe faults in wind turbine units, a tiered disconnection control strategy can be adopted in practical applications: the frame circuit breaker is triggered first to disconnect, and only after the main contacts of the frame circuit breaker are reliably disconnected is the grid-connected contactor controlled to trip. This method ensures that the frame circuit breaker with a larger breaking capacity undertakes the task of disconnecting the large fault current, avoiding contact burn-out or welding of the grid-connected contactor due to the interruption of the fault current, thus eliminating safety hazards.

[0076] In the standby state of a doubly-fed induction generator (DFIG) wind turbine, if both the grid-connected contactor and the frame circuit breaker are simultaneously closed, an open-circuit voltage will be induced on the generator rotor side. This voltage, after uncontrolled rectification by the generator-side converter, will cause the DC bus voltage to rise to approximately 2600V, far exceeding the withstand capability of the power unit and DC bus capacitors, potentially leading to damage to converter components or even a fire. Therefore, see [reference needed]. Figure 2 As shown, in the standby state of the wind turbine, it first enters state 1, which is a self-test. Then, a grid-connected contactor contact sticking monitoring function is added to the control algorithm. That is, during the converter startup process, if the grid-connected contactor is detected to be closed, the frame circuit breaker is prohibited from being closed, and a grid-connected contactor fault is immediately reported. If the grid-connected contactor is detected to be not closed, it enters state 2 and waits for the generator speed to rise.

[0077] During the shutdown of a doubly-fed induction generator (DFIG) wind turbine, when the generator speed drops to the off-grid speed, the control system issues a trip command to the grid-connected contactor. If the grid-connected contactor fails to trip properly due to main contact sticking or control signal failure, the generator rotor voltage will continue to rise as the speed decreases further. This voltage, after uncontrolled rectification by the generator-side converter, will cause the DC bus voltage to rise, thereby triggering the internal Crowbar and Chopper circuits for an extended period. This may cause the aforementioned hardware damage, or even lead to a fire or tower collapse.

[0078] To address this issue, this invention proposes a control algorithm that takes into account both the mechanical action time of the grid-connected contactor and the rate of change of the wind turbine's shutdown speed. Figure 3 This paper illustrates a wind turbine grid disconnection control process. Once the turbine reaches the preset grid disconnection speed, the control system first actively reduces the load to an unloaded state and sends a tripping command to the grid-connected contactor. Subsequently, the system enters a status monitoring phase to determine whether the main contacts of the grid-connected contactor have reliably disconnected. If the contactor is detected to be disconnected, the pulse blocking procedure will be executed normally and the shutdown process will be completed. If no disconnection signal is detected, the system will wait 200 milliseconds before issuing the trip command again and performing a secondary status check. If the contactor is still not disconnected during the second judgment, it is determined that the grid-connected contactor is faulty, and the frame circuit breaker is immediately triggered to trip, thereby forcibly disconnecting the main circuit and reporting the fault.

[0079] This process, by introducing a 200-millisecond retry mechanism and secondary confirmation logic, not only ensures timely response when disconnected from the network, but also significantly improves the fault tolerance capability for occasional contactor jamming or signal abnormalities. Furthermore, it uses a frame circuit breaker as the final protection measure to effectively avoid equipment damage and safety risks caused by contactor failure to operate.

[0080] In summary, this invention optimizes the tripping sequence of the grid-connected contactor, improving the original "synchronization of blocking pulse and tripping" to "blocking pulse only after main contact disconnection is detected," thus avoiding tripping with excitation current and reducing the risk of contact sticking. Simultaneously, a fault classification management mechanism is established, prioritizing the disconnection of the frame circuit breaker in case of severe faults, and only disconnecting the grid-connected contactor after its reliable disconnection, ensuring that the large fault current is handled by a circuit breaker with a larger breaking capacity, eliminating safety hazards. Furthermore, a fault mode identification module for the grid-connected contactor and frame circuit breaker is added to achieve intelligent optimization of their control methods and timing, comprehensively improving the operational safety and reliability of the doubly-fed wind turbine under start-up, shutdown, and fault conditions. Based on the above method embodiments, this application also provides a wind turbine grid-connected contactor control system, see [link to relevant documentation]. Figure 4 As shown, the system mainly includes the following parts: The tripping command response unit 410 is used to respond to the tripping command of the grid-connected contactor and start continuous monitoring of the actual disconnection status of the main contacts of the grid-connected contactor. The first disconnection judgment unit 420 is used to send a blocking pulse command to the converter if the main contact is detected to be disconnected within a preset time threshold. The retransmission and re-monitoring unit 430 is used to resend the grid-connected contactor tripping command and restart the monitoring of the main contact disconnection status if the main contact is not detected to be open within a preset time threshold. The over-level protection execution unit 440 is used to open the control frame circuit breaker and terminate the current grid-connected contactor tripping operation if the main contact is not detected to be open during the secondary monitoring process of the preset time threshold.

[0081] In one feasible implementation, the above-mentioned tripping command response unit 410 is used for: In response to the tripping command of the grid-connected contactor, the mechanical action characteristic parameters are dynamically adjusted according to the current cumulative operating time and historical number of operations of the grid-connected contactor; The time window for determining whether the main contact has opened is determined based on the adjusted mechanical motion characteristic parameters. Within the time window, the on / off signals of the auxiliary contacts of the grid-connected contactor and the main circuit current signal are continuously collected, and the actual disconnection time of the main contacts is identified based on the timing coordination relationship between the two, so as to continuously monitor the actual disconnection state of the main contacts.

[0082] In one feasible implementation, the first disconnection determination unit 420 is used to: If the main contact is detected to be open within the preset time threshold, continuously verify whether the main circuit current has decayed to below the zero current threshold. After confirming that the current decay is complete and remains stable, a blocking pulse command is sent to the converter to enable continuous monitoring of the actual open state of the main contacts to support the safe blocking of the converter.

[0083] In one feasible implementation, the retransmission and remonitoring unit 430 is used for: After the initial tripping command is issued and no main contact disconnection is detected, a reverse demagnetizing pulse is applied to the control coil of the grid-connected contactor, and the tripping command is reissued simultaneously. Initiate a new round of main contact disconnection status monitoring, and simultaneously record the coil drive voltage and auxiliary contact response delay during this round of monitoring, so as to continuously monitor the actual disconnection status of the main contacts.

[0084] In one feasible implementation, the above-mentioned over-level protection execution unit 440 is used for: When the secondary monitoring process is completed and it is still confirmed that the main contacts have not been disconnected, a disconnect command is sent to the control frame circuit breaker. After detecting that the main contacts of the control frame circuit breaker are open, the power supply to the grid-connected contactor control circuit is cut off, and the permanent fault flag of the grid-connected contactor is set so as to trigger the fault isolation operation triggered by continuous monitoring of the actual open state of the main contacts.

[0085] In one feasible implementation, the aforementioned tripping command response unit 410 is further configured to: When the wind turbine control system detects a serious fault, it suspends the execution of the grid-connected contactor tripping command and instead sends a disconnect command to the frame circuit breaker. After detecting that the main contacts of the frame circuit breaker are open, a tripping command is sent to the grid-connected contactor, and continuous monitoring of the actual open state of the main contacts is started simultaneously.

[0086] In one feasible implementation, the system further includes a status monitoring and processing module, used for: When the wind turbine is in standby mode, the main circuit voltage signal and auxiliary contact status signal of the grid-connected contactor are continuously collected. If a continuous voltage is detected in the main circuit and the auxiliary contact is in the closed state when the frame circuit breaker is in the open state, it is determined that the main contact of the grid-connected contactor is stuck, and the closing command to the frame circuit breaker is prohibited. At the same time, a grid-connected contactor sticking fault alarm is generated. When the wind turbine is in the shutdown process and the generator speed reaches the off-grid speed threshold, a grid-connected contactor tripping command is issued, and the main contact disconnection status monitoring is initiated. If the main contact disconnection is not detected within the preset time threshold, a secondary tripping and frame circuit breaker linkage disconnection operation is performed to achieve start-stop safety protection supported by continuous monitoring of the actual disconnection status of the main contact.

[0087] The wind turbine grid-connected contactor control system provided in this application has the same implementation principle and technical effects as the aforementioned method embodiments. For the sake of brevity, any parts not mentioned in the embodiments of the wind turbine grid-connected contactor control system can be referred to the corresponding content in the aforementioned wind turbine grid-connected contactor control method embodiments.

[0088] The terminal device described in this invention is an embedded edge execution device, deployed in the converter cabinet, and directly connected in series between the contactor / circuit breaker drive circuit and the main control system, used to implement the wind turbine grid-connected contactor control method described in any of the aforementioned embodiments.

[0089] The terminal device receives the grid-connected contactor disconnection command issued by the main control system, and after issuing the command, monitors whether the grid-connected contactor is actually disconnected; after confirming that it is actually disconnected, it sends a blocking pulse signal to the converter.

[0090] When a serious fault occurs, the terminal device will first output a command to disconnect the frame circuit breaker; after the frame circuit breaker is detected to have disconnected, it will then output a command to disconnect the grid-connected contactor.

[0091] The terminal equipment has fault mode recognition functions for grid-connected contactors and frame circuit breakers: when the converter starts up, if the grid-connected contactor is detected to be closed, the frame circuit breaker will be prevented from closing and a grid-connected contactor fault will be reported; during the wind turbine shutdown process, if the grid-connected contactor is not detected to be disconnected 200ms after the first grid disconnection command is issued, a second grid disconnection command will be sent; if it is still detected to be disconnected at this time, a grid-connected contactor fault will be reported, the frame circuit breaker will be disconnected, and a fault shutdown will be performed.

[0092] Through the above logic, the terminal device realizes the localized and closed-loop execution of the control timing and fault handling process of the grid-connected contactor, without relying on the real-time intervention of the main control system, and can implement the control method proposed in this invention.

[0093] This application also provides a computer-readable storage medium storing computer-executable instructions. When these computer-executable instructions are called and executed by a processor, they cause the processor to implement the above-described wind turbine grid-connected contactor control method. For specific implementation details, please refer to the foregoing method embodiments, which will not be repeated here.

[0094] The computer program product of the wind turbine grid-connected contactor control method, system and terminal equipment provided in the embodiments of this application includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the methods described in the preceding method embodiments. For specific implementation, please refer to the method embodiments, which will not be repeated here.

[0095] Unless otherwise specifically stated, the relative steps, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0096] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0097] In the description of this application, it should be noted that the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for controlling a grid-connected contactor of a wind turbine generator, characterized in that, include: In response to the tripping command of the grid-connected contactor, continuous monitoring of the actual disconnection status of the main contacts of the grid-connected contactor is initiated. If the main contact is detected to be open within the preset time threshold, a blocking pulse command is sent to the converter. If the main contact is not detected to be open within the preset time threshold, the grid-connected contactor tripping command is sent again, and the monitoring of the main contact open state is restarted. If the main contact is not detected to be open during the secondary monitoring process within the preset time threshold, the control frame circuit breaker will be opened, and the current grid-connected contactor tripping operation will be terminated.

2. The wind turbine grid-connected contactor control method according to claim 1, characterized in that, In response to the grid-connected contactor tripping command, continuous monitoring of the actual open state of the main contacts of the grid-connected contactor is initiated, including: In response to the tripping command of the grid-connected contactor, the mechanical action characteristic parameters are dynamically adjusted according to the current cumulative operating time and historical number of operations of the grid-connected contactor; The time window for determining whether the main contact has opened is determined based on the adjusted mechanical motion characteristic parameters. Within the time window, the on / off signals of the auxiliary contacts of the grid-connected contactor and the main circuit current signal are continuously collected, and the actual disconnection time of the main contacts is identified based on the timing coordination relationship between the two, so as to continuously monitor the actual disconnection state of the main contacts.

3. The wind turbine grid-connected contactor control method according to claim 1, characterized in that, If the main contact is detected to be open within a preset time threshold, a blocking pulse command is sent to the converter, including: If the main contact is detected to be open within the preset time threshold, continuously verify whether the main circuit current has decayed to below the zero current threshold. After confirming that the current decay is complete and remains stable, a blocking pulse command is sent to the converter to enable continuous monitoring of the actual open state of the main contacts to support the safe blocking of the converter.

4. The wind turbine grid-connected contactor control method according to claim 1, characterized in that, If no main contact disconnection is detected within the preset time threshold, the grid-connected contactor tripping command is sent again, and monitoring of the main contact disconnection status is restarted, including: If the auxiliary normally closed contact is not detected to change from closed to open within a preset time threshold after the first trip command is issued, the grid-connected contactor trip command will be output to the grid-connected contactor control circuit again. While outputting the grid-connected contactor tripping command again, the monitoring timer is reset and the current sampling buffer is cleared, and the continuous acquisition and status identification of the auxiliary normally closed contact on / off signal is restarted.

5. The wind turbine grid-connected contactor control method according to claim 1, characterized in that, If no main contact disconnection is detected during the secondary monitoring process within the preset time threshold, the control frame circuit breaker will disconnect, and the current grid-connected contactor tripping operation will be terminated, including: When the secondary monitoring process is completed and it is still confirmed that the main contacts have not been disconnected, a disconnect command is sent to the control frame circuit breaker. If the main contact is not detected to be open during the secondary monitoring process within the preset time threshold, the control frame circuit breaker will be opened, and the current grid-connected contactor tripping operation will be terminated.

6. The wind turbine grid-connected contactor control method according to claim 1, characterized in that, In response to the tripping command of the grid-connected contactor, continuous monitoring of the actual open state of the main contacts of the grid-connected contactor is initiated, which also includes: When the wind turbine control system detects a serious fault, it suspends the execution of the grid-connected contactor tripping command and instead sends a disconnect command to the frame circuit breaker. After detecting that the main contacts of the frame circuit breaker are open, a tripping command is sent to the grid-connected contactor, and continuous monitoring of the actual open state of the main contacts is started simultaneously.

7. The wind turbine grid-connected contactor control method according to claim 1, characterized in that, The method further includes: When the wind turbine is in standby mode, the main circuit voltage signal and auxiliary contact status signal of the grid-connected contactor are continuously collected. If a continuous voltage is detected in the main circuit and the auxiliary contact is in the closed state when the frame circuit breaker is in the open state, it is determined that the main contact of the grid-connected contactor is stuck, and the closing command to the frame circuit breaker is prohibited. At the same time, a grid-connected contactor sticking fault alarm is generated. When the wind turbine is in the shutdown process and the generator speed reaches the off-grid speed threshold, a grid-connected contactor tripping command is issued, and the main contact disconnection status monitoring is initiated. If the main contact disconnection is not detected within the preset time threshold, a secondary tripping and frame circuit breaker linkage disconnection operation is performed to achieve start-stop safety protection supported by continuous monitoring of the actual disconnection status of the main contact.

8. A grid-connected contactor control system for wind turbine generators, characterized in that, include: The tripping command response unit is used to respond to the tripping command of the grid-connected contactor and start continuous monitoring of the actual disconnection status of the main contacts of the grid-connected contactor. The first disconnection judgment unit is used to send a blocking pulse command to the converter if the main contact is detected to be disconnected within a preset time threshold. The retransmission and remonitoring unit is used to resend the grid-connected contactor tripping command and restart the monitoring of the main contact disconnection status if the main contact is not detected to be open within the preset time threshold. The over-level protection execution unit is used to control the circuit breaker to open and terminate the current grid-connected contactor tripping operation if the main contact is not detected to be open during the secondary monitoring process of the preset time threshold.

9. A terminal device, characterized in that, The terminal device is an embedded edge execution device, deployed in the converter cabinet, and directly connected in series between the contactor / circuit breaker drive circuit and the main control system, used to implement the wind turbine grid-connected contactor control method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when invoked and executed by a processor, cause the processor to implement the wind turbine grid-connected contactor control method according to any one of claims 1 to 7.

Images