Operation mode cooperative control method for network-forming type wind turbine generator

Abstract

The invention, which relates to the technical field of the cooperative control of the operation modes of the network-forming type wind turbine generator set, discloses a cooperative control method for the operation modes of the network-forming type wind turbine generator set, and the method comprises the steps: collecting the voltage, the frequency and the change rate of a grid-connected point in real time, and judging whether the power grid strength is insufficient or not based on a multi-dimensional power grid state parameter; when it is judged that the power grid strength is insufficient, a maintaining-switching-updating three-stage mode switching strategy is executed, grid-connected converter modulation waves are kept unchanged at the switching moment, then a control algorithm is switched, and network construction control parameters are pre-synchronized to generate new modulation wave signals; controlling the grid-connected converter to operate as a voltage source in a grid construction mode, and generating an output control signal according to the pre-synchronized voltage reference value and frequency reference value; the synchronous control energy storage bidirectional converter adopts a feed-forward PI control strategy to eliminate the deviation between the actual output power of the fan and the load power demand and realize power balance support.

Description

Technical Field

[0001] This invention relates to the field of collaborative control technology for the operation modes of grid-connected wind turbines, and in particular to a collaborative control method for the operation modes of grid-connected wind turbines. Background Technology

[0002] Grid-based wind power systems, as a crucial supporting unit of the new power system, are widely used in weak grid scenarios such as offshore wind power and remote areas. With the integration of energy storage systems and grid control technologies, traditional wind turbines have evolved into complex systems comprising dual energy sources (wind power generation + energy storage) and dual converters (wind power converter + energy storage DC / DC converter). Specifically, this technology system covers the entire process from grid state detection and control mode decision-making to multi-controller collaborative execution, including key aspects such as phase-locked loop-based vector control, voltage-power droop control, and fast PI control. Among these, the grid strength assessment method constructs a multi-dimensional evaluation system by real-time acquisition of grid connection point voltage, frequency, and their rate of change, providing a decision-making basis for mode switching.

[0003] However, existing wind and energy storage coordinated control methods directly employ single-mode switching logic without establishing a complete multi-controller coordination mechanism. This can lead to significant impacts during sudden changes in grid strength. Specifically, when the grid connection point voltage... Below the set threshold And the duration exceeds or frequency deviation exceeding And the rate of change exceeds Traditional control strategies suffer from three core flaws: First, sudden changes in modulation waves during control algorithm switching can cause transient inrush currents that can reach 2-3 times the rated value; second, the control targets of the energy storage system are not adjusted synchronously, resulting in DC bus voltage fluctuations exceeding ±15%; and third, conflicts between the phase-locked loop (PLL) and the grid-connected algorithm can lead to control failures. These flaws not only reduce system reliability but may also cause wind farms to disconnect from the grid due to protection malfunctions, severely restricting the engineering application of grid-connected wind power systems in weak grid scenarios. Summary of the Invention

[0004] The main objective of this invention is to provide a collaborative control method for the operation mode of grid-connected wind turbine units.

[0005] Another objective of this invention is to propose a collaborative control device for the operation mode of a grid-type wind turbine.

[0006] The third objective of this invention is to provide a computer device.

[0007] A fourth objective of this invention is to provide a non-transitory computer-readable storage medium.

[0008] To achieve the above objectives, a first aspect of the present invention proposes a collaborative control method for the operation mode of a grid-connected wind turbine, comprising: S1 collects the voltage, frequency and rate of change of the grid connection point in real time, and determines whether the grid strength is insufficient based on multi-dimensional grid state parameters. S2, when the grid strength is determined to be insufficient, a three-stage mode switching strategy of hold-switching-update is executed. During the switching moment, the modulation wave of the grid-connected converter is kept unchanged, and then the control algorithm is switched and the grid construction control parameters are pre-synchronized to generate a new modulation wave signal. S3 controls the grid-connected converter to operate as a voltage source in grid-connected mode, generating an output control signal based on the pre-synchronized voltage reference value and frequency reference value. S4, the synchronous control energy storage bidirectional converter adopts a feedforward PI control strategy to eliminate the deviation between the actual output power of the wind turbine and the load power demand, and achieve power balance support.

[0009] In one embodiment of the present invention, the real-time acquisition of grid connection point voltage, frequency and their rate of change, and the determination of whether the grid strength is insufficient based on multi-dimensional grid state parameters, further includes: S11, when the grid connection point voltage Voltage below the set grid connection point low threshold And the duration exceeds At that time, the power grid strength was determined to be insufficient; S12, when the absolute value of the deviation between the sampling frequency at the grid connection point and the rated frequency is... Exceeding the set grid connection point frequency deviation threshold And the absolute value of the rate of change of frequency Exceeding the set threshold for the rate of change of frequency At that time, the power grid strength was determined to be insufficient.

[0010] In one embodiment of the present invention, the three-stage mode switching strategy of maintaining-switching-updating further includes: S21, calculate the reference value of the output voltage required to maintain the rated voltage and frequency based on the real-time current detected by grid connection. and frequency reference value The formula for calculating the voltage reference value is as follows: The formula for calculating the frequency reference value is: , and This is the preset scaling factor.

[0011] In one embodiment of the present invention, controlling the grid-connected converter to operate as a voltage source in grid-connected mode further includes: S31, by tracking the pre-synchronized voltage reference value and frequency reference value Generate an output control signal, in which the voltage reference value The calculation includes the grid voltage amplitude compensation term. and phase compensation terms ,satisfy and .

[0012] In one embodiment of the present invention, the synchronous control energy storage bidirectional converter adopts a feedforward PI control strategy and further includes: S41 adjusts the output power of the energy storage converter in real time through a feedforward PI controller to ensure the actual output power of the wind turbine. With load power requirements deviation Control precision reached Rated power.

[0013] In one embodiment of the present invention, it further includes: S5, when the wind turbine is operating in grid-connected mode, monitors the state of charge of the energy storage system in real time. ,like Below the preset lower threshold Or higher than the preset upper limit threshold If this occurs, the energy storage system will be triggered to enter a degraded operation mode and an energy status warning signal will be sent.

[0014] To achieve the above objectives, a second aspect of the present invention provides a collaborative control device for the operation mode of a grid-connected wind turbine, comprising: The power grid status monitoring module is used to collect the voltage, frequency and rate of change of the grid connection point in real time, and to determine whether the power grid strength is insufficient based on multi-dimensional power grid status parameters. The mode switching control module is used to execute a three-stage mode switching strategy of hold-switching-update when the grid strength is determined to be insufficient. During the switching moment, the modulated wave of the grid-connected converter is kept unchanged. Then, the control algorithm is switched and the grid construction control parameters are pre-synchronized to generate a new modulated wave signal. The voltage source control module is used to control the grid-connected converter to operate as a voltage source in grid-connected mode, and generates output control signals based on the pre-synchronized voltage reference value and frequency reference value; The energy storage power balancing module is used to synchronously control the bidirectional energy storage converter using a feedforward PI control strategy to eliminate the deviation between the actual output power of the wind turbine and the load power demand, thereby achieving power balance support.

[0015] To achieve the above objectives, a third aspect of this application provides a computer device, including a processor and a memory; wherein the processor reads executable program code stored in the memory to run a program corresponding to the executable program code, for implementing a collaborative control method for grid-connected wind turbine operation modes as described in the first aspect embodiment.

[0016] To achieve the above objectives, the fourth aspect of this application proposes a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements a collaborative control method for the operation mode of a grid-connected wind turbine as described in the first aspect embodiment.

[0017] The embodiments of the present invention have the following beneficial effects: This invention enables truly smooth and seamless switching between grid-connected and grid-connected modes for wind turbines. During mode switching, by maintaining the timing control of the modulation wave, switching algorithm, and updated modulation wave, and by pre-synchronizing the algorithm, current and voltage surges during mode switching are eliminated, improving system reliability. In grid-connected mode, the grid-connected converter provides grid support by stabilizing the voltage, while the energy storage system is responsible for power balance stabilization. The decoupling design of these two systems ensures stable system support. This method does not rely on specific hardware parameters, is applicable to wind turbines of different power levels and energy storage configurations, and can be extended to the coordinated control of multiple turbines connected in parallel for grid connection. Attached Figure Description

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 A flowchart of a collaborative control method for the operation mode of a grid-connected wind turbine provided in an embodiment of the present invention; Figure 2 An architecture diagram of a collaborative control system for the operation mode of a grid-type wind turbine provided in an embodiment of the present invention; Figure 3 A flowchart of a grid strength determination method for a collaborative control method of a grid-connected wind turbine operating mode provided in an embodiment of the present invention; Figure 4 A flowchart illustrating the switching process between the generator unit and the grid-connected network mode in a collaborative control method for grid-connected wind turbine operation modes provided in this embodiment of the invention. Figure 5 A flowchart of a weak grid mode control method for a collaborative control method of a grid-connected wind turbine operation mode provided in an embodiment of the present invention; Figure 6 This is a structural diagram of a grid-type wind turbine operation mode collaborative control device provided in an embodiment of the present invention. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] The following description, with reference to the accompanying drawings, describes a collaborative control method and apparatus for the operation mode of a grid-type wind turbine according to an embodiment of the present invention.

[0022] Example 1 This embodiment provides a collaborative control method for the operation mode of grid-connected wind turbine units. For example... Figure 1 As shown, the method includes the following steps: S1 collects the voltage, frequency and rate of change of the grid connection point in real time, and determines whether the grid strength is insufficient based on multi-dimensional grid state parameters.

[0023] Specifically, in some implementations, the grid connection point voltage is collected in real time. ,frequency and its rate of change This is one of the key steps in determining grid strength in this invention. This step utilizes high-precision voltage and frequency sensors deployed at the wind turbine grid connection point, combined with digital signal processing technology, to achieve dynamic monitoring of the grid status. The acquisition frequency is typically set above 1000 Hz to ensure a rapid response to grid disturbances. The acquired voltage signal undergoes low-pass filtering to remove high-frequency noise, while the frequency signal's instantaneous value is extracted using a digital phase-locked loop (DPLL) or fast Fourier transform (FFT) algorithm.

[0024] In this embodiment of the invention, the criteria for determining insufficient grid strength include: when the voltage at the grid connection point... Below the set low voltage threshold (Typically 90%~95% of the rated voltage, i.e.) And the duration exceeds (Generally 100~300 ms), then the grid strength insufficiency judgment is triggered; or when the grid connection point frequency... With rated frequency absolute value of deviation Exceeding the set frequency deviation threshold (Typically ±0.5 Hz), and the rate of frequency change Exceeding the set frequency change rate threshold (Typically ±0.1 Hz / s), which also indicates insufficient grid strength. The settings of these parameters must comply with the requirements for grid disturbance response in grid connection standards such as IEC 61400-25 and IEEE 1547.

[0025] Specifically, this step is widely applicable to real-time response control of wind farms under abnormal operating conditions such as grid faults, voltage drops, and frequency fluctuations. By quickly identifying changes in grid strength, the system can promptly activate grid connection mode, enabling wind turbines to actively support grid voltage and frequency, thereby improving the operational stability and grid connection security of wind farms under weak grid conditions.

[0026] This step provides a reliable basis for subsequent operation mode switching, ensuring that wind turbines can quickly and seamlessly switch from grid-connected mode to grid-connected mode when grid disturbances occur, avoiding system instability or equipment damage caused by mismatched control strategies. Simultaneously, the comprehensive assessment of multi-dimensional parameters improves the accuracy and robustness of grid status identification, laying a solid foundation for the coordinated control of energy storage systems and grid-connected converters.

[0027] Further, step S1 includes: S11, when the grid connection point voltage Voltage below the set grid connection point low threshold And the duration exceeds At that time, the power grid strength was determined to be insufficient.

[0028] Specifically, when the grid connection point voltage The voltage is lower than the set low threshold of the grid connection point. And the duration exceeds When the grid strength is insufficient, it is determined that the grid strength is insufficient. This is one of the key judgment criteria for grid state identification and operation mode switching in this invention. This step is based on real-time monitoring of the grid connection point voltage and time logic judgment, aiming to accurately identify the weakened state of the grid, thereby triggering the wind turbine to switch from grid-following mode to grid-connecting mode to maintain stable system operation.

[0029] In this embodiment of the invention, this step involves continuously collecting the grid connection point voltage signal through a voltage monitoring module deployed in the wind turbine main controller or grid-connected coordination controller. and compare it with the preset low voltage threshold. Compare. The threshold. Typically set according to power grid standards (such as IEEE 1547 or GB / T 19939), the value is generally taken as 85% to 90% of the rated voltage. .when When the voltage is below a threshold, the system starts a timer to record the duration. If this duration exceeds the set delay threshold... If the grid strength is insufficient, the system will proceed with the mode switching process.

[0030] Furthermore, The settings need to balance the persistence of power grid disturbances with the timeliness of system response. In practical engineering, The timeout is typically set between 50ms and 200ms, with the specific value depending on grid inertia, wind turbine response speed, and the coordination requirements of protection mechanisms. This parameter setting must comply with the grid fault response time requirements in relevant standards such as IEC 61400-25 or IEC 61850.

[0031] Therefore, this step is applicable to identifying the operating status of wind turbines in scenarios involving weak power grids or grid faults. For example, in offshore wind farms or remote power grids, voltage drops may persist for extended periods due to high grid impedance or long fault recovery times. In such cases, this judgment mechanism can effectively identify the weakened state of the power grid, preventing the turbine from frequently switching control modes due to misjudgments, thereby improving the stability and reliability of system operation.

[0032] The technical advantage of this step lies in achieving accurate identification of grid strength by setting reasonable voltage thresholds and duration parameters, providing a reliable basis for subsequent grid configuration mode switching. When grid voltage is abnormal, the grid configuration control logic is activated promptly, switching the grid-connected converter from current-source control to voltage-source control, thereby maintaining grid connection point voltage stability, preventing system instability or equipment damage, and significantly improving the adaptability and operational safety of wind turbine units in complex grid environments.

[0033] S12, when the absolute value of the deviation between the sampling frequency at the grid connection point and the rated frequency is... Exceeding the set grid connection point frequency deviation threshold And the absolute value of the rate of change of frequency Exceeding the set threshold for the rate of change of frequency At that time, the power grid strength was determined to be insufficient.

[0034] Specifically, in some implementations, when the grid connection point collects data at a frequency... With rated frequency absolute value of deviation Exceeding the set grid connection point frequency deviation threshold And the absolute value of the rate of change of frequency Exceeding the set threshold for the rate of change of frequency At this point, the system determines that the grid strength is insufficient. This step is one of the key criteria for switching the operating mode of grid-connected wind turbines, used to identify abnormal states of the grid in terms of frequency stability, thereby triggering the switch from grid-following mode to grid-connected mode.

[0035] In this embodiment of the invention, this step relies on a high-precision frequency acquisition and real-time calculation module. Grid connection point frequency. Real-time measurements are typically performed using phase-locked loops (PLLs) or digital frequency detection algorithms (such as Fourier transform or zero-crossing detection), with sampling frequencies generally no lower than 1 kHz to ensure rapid response to frequency changes. Frequency deviation is calculated using the absolute value of the difference, i.e. ,in This refers to the rated frequency of the power grid, typically 50 Hz or 60 Hz, depending on the grid standards. Frequency variation rate. The instantaneous trend of frequency change is captured by using a difference algorithm, such as sliding window difference or first-order difference method.

[0036] Furthermore, It is usually set between 0.5 Hz and 1.0 Hz, and the specific value can be adjusted according to the power grid standard and the system response speed; The settings are typically between 0.1 Hz / s and 0.5 Hz / s to identify rapid frequency fluctuations. These parameters must meet the response requirements for frequency deviation and rate of change in wind power grid connection standards such as IEC 61400-25 or GB / T 19963 to ensure that the system can respond promptly to grid disturbances.

[0037] Specifically, this step is widely applicable to the operation and control of wind farms under weak grid conditions or grid faults. For example, when the grid frequency experiences a sudden change or sustained deviation, the system uses this frequency criterion to identify a decline in grid support capacity, thereby triggering grid connection control logic to enable wind turbines to actively support grid voltage and frequency. This step, together with the grid connection point voltage criterion, constitutes a dual mechanism for grid strength determination, improving the system's accuracy and robustness in identifying grid conditions.

[0038] Furthermore, this step, by introducing dual criteria of frequency deviation and frequency change rate, effectively improves the sensitivity and response speed for identifying abnormal grid conditions. Compared to a single frequency deviation criterion, this method can more accurately capture dynamic changes in grid frequency, avoiding misjudgments or omissions, thereby ensuring that wind turbines can switch to grid-connected mode in a timely manner when grid strength is insufficient, maintaining stable system operation. This technology plays a crucial supporting role in the multi-controller collaborative control of grid-connected wind turbines and is a key link in achieving seamless system switching and stable grid connection.

[0039] S2, when the grid strength is determined to be insufficient, a three-stage mode switching strategy of hold-switching-update is executed. During the switching moment, the modulation wave of the grid-connected converter is kept unchanged, and then the control algorithm is switched and the grid construction control parameters are pre-synchronized to generate a new modulation wave signal.

[0040] Specifically, when the grid strength is deemed insufficient, this invention employs a three-stage mode switching strategy of "maintain-switch-update" to achieve a smooth and uninterrupted transition of wind turbines from grid-following mode to grid-connected mode. The core of this strategy lies in effectively suppressing voltage and current surges that may occur during mode switching through reasonable control timing and parameter pre-synchronization mechanisms, thereby improving the stability and reliability of system operation.

[0041] Furthermore, when the grid strength determination module detects the grid connection point voltage... Below the set threshold And the duration exceeds or grid connection frequency With rated frequency absolute value of deviation Exceeding the frequency deviation threshold and the rate of change of frequency Exceeding the set rate of change threshold When this occurs, the system will trigger a mode switch. At the moment of switchover, the current modulation signal of the grid-connected converter is kept unchanged to maintain the continuity of output power and avoid current or voltage jumps caused by sudden changes in the control algorithm. Subsequently, the system switches the control algorithm of the grid-connected converter from vector control based on a phase-locked loop (PLL) to a grid-connected control algorithm. This algorithm calculates the maintenance voltage based on the real-time detected grid-side current. and frequency The required output voltage reference value. Finally, after the algorithm switch is completed, the system generates a new modulation wave signal according to the network control algorithm to achieve a smooth transition of the control target.

[0042] In this embodiment of the invention, the voltage threshold The time threshold is typically set at 90% to 95% of the rated voltage. The frequency deviation threshold is typically set to 50~100 ms. The frequency change rate threshold is ±0.5 Hz. The value is ±0.1 Hz / s. These parameters must be set in accordance with wind power grid connection standards such as IEC 61400-25 and GB / T 19963 to ensure that the system has a rapid response capability when the grid is disturbed.

[0043] This strategy is suitable for scenarios with low grid strength, such as offshore wind farms and wind farms in remote areas. In these scenarios, grid inertia is low, and voltage and frequency are easily affected by disturbances, requiring wind turbines to have the ability to actively support the grid. Through this strategy, the turbines can quickly switch to grid-connected mode under grid fault or weak grid conditions, maintaining local grid voltage and frequency stability. Simultaneously, the energy storage system eliminates power deviations through rapid PI control. Ensure DC bus voltage Within the set range run.

[0044] The technical advantage of this step lies in the fact that, by maintaining the modulation wave constant and coordinating the switching of control algorithms with parameter pre-synchronization, the dynamic impact during mode switching is significantly reduced, improving the system's robustness and response speed under grid disturbances. Simultaneously, this strategy provides a fundamental guarantee for the stable operation of wind turbines in grid-connected modes, enhancing their support capabilities in weak grid environments, and possesses significant engineering application value.

[0045] Further, step S2 includes: S21, calculate the reference value of the output voltage required to maintain the rated voltage and frequency based on the real-time current detected by grid connection. and frequency reference value The formula for calculating the voltage reference value is as follows: The formula for calculating the frequency reference value is: , and This is the preset scaling factor.

[0046] Specifically, in weak grid operation mode, the wind turbine dynamically calculates the output voltage reference value required to maintain rated voltage and frequency by using the real-time current signal detected by grid connection. and frequency reference value This is to achieve rapid response and stable support for the grid-based control strategy. This step is one of the core components of the grid-based control algorithm. Its technical implementation is based on the proportional control principle, combined with real-time feedback of the grid status, to ensure that when the grid voltage or frequency is abnormal, the unit can quickly switch to the voltage source type operation mode to maintain the voltage and frequency stability of the grid connection point (PCC).

[0047] In this embodiment of the invention, the voltage reference value The calculation formula is: ,in The rated voltage reference value is usually set to the grid standard voltage (such as 690 V or 10 kV, depending on the voltage level to which the unit is connected). This indicates the real-time detected grid-connected current deviation. This is a preset proportional gain coefficient used to adjust the degree to which current changes affect the voltage reference value. This gain coefficient needs to be tuned based on the system impedance characteristics, grid inertial response time, and converter dynamic response capability, typically within a certain range. The V / A range is set to ensure that the system has good dynamic adjustment performance under different operating conditions.

[0048] Furthermore, frequency reference value The calculation formula is: ,in The rated frequency of the power grid (usually 50 Hz or 60 Hz). This represents the rate of change of the frequency at the grid connection point, used to reflect the instantaneous fluctuation trend of the grid frequency. This is the frequency adjustment proportional coefficient, usually set to... Within the Hz / (Hz / s) range, a balance is struck between frequency response speed and system stability.

[0049] In practical applications, this step primarily addresses abnormal operating conditions such as grid voltage dips or frequency fluctuations. It involves rapidly adjusting the output voltage and frequency reference values ​​of the grid-connected converter to actively support the grid. For example, when the grid frequency drops rapidly, by increasing... This method can guide the converter to output a voltage signal slightly higher than the current frequency, thereby providing frequency support and preventing system instability. Furthermore, this method is applicable to wind turbines of different power ratings and does not depend on specific hardware parameters, exhibiting good versatility and scalability.

[0050] Specifically, this step effectively improves the dynamic response capability and voltage and frequency support accuracy of grid-connected wind turbines under weak grid conditions, and provides a key reference signal generation mechanism for realizing the coordinated control of wind turbines and energy storage systems. This ensures the continuity and stability of the system during mode switching, significantly reduces the risk of voltage / frequency surges, and enhances the grid's adaptability.

[0051] S3 controls the grid-connected converter to operate as a voltage source in grid-connected mode, generating output control signals based on the pre-synchronized voltage reference value and frequency reference value.

[0052] Specifically, in grid-connected mode, controlling the grid-connected converter to operate as a voltage source is a crucial step in ensuring that wind turbines stably support grid voltage and frequency under weak grid conditions. This step obtains the grid voltage reference value through a pre-synchronization mechanism. and frequency reference value Based on these reference values, output control signals are generated to drive the grid-connected converter to output stable AC voltage and frequency, thereby achieving active support for the power grid.

[0053] In this embodiment of the invention, this step first relies on the power grid status detection module to collect the voltage at the grid connection point in real time. and frequency And calculate the rate of change of frequency. When insufficient grid strength is detected (e.g.) And the duration exceeds ,or and The grid-connected converter will trigger a mode switch, putting it into grid-connected control mode. At this time, the control algorithm of the grid-side converter will switch from vector control based on phase-locked loop (PLL) to grid-connected control algorithm, such as virtual synchronous machine (VSG) or droop control.

[0054] In the network control algorithm, the system is based on the pre-synchronized... and Combined with real-time detected grid connection point current The system calculates the reference output voltage value required to maintain the rated voltage and frequency. This reference value is adjusted by a fast PI controller with feedforward compensation to generate a modulation wave signal, driving the converter to output voltage and frequency that meet the grid requirements. To achieve bumpless switching, the modulation wave remains unchanged at the moment of switching and is then updated gradually to ensure a smooth dynamic response of the system and avoid sudden voltage or current changes.

[0055] Furthermore, It is usually set to the rated mains voltage (such as 690 V or 10 kV). The rated frequency (e.g., 50 Hz or 60 Hz). The parameters of the PI controller need to be tuned according to the dynamic response characteristics of the system, typically including the proportional gain. and integral gain This ensures that the system has good stability and response speed under different loads and power grid disturbances.

[0056] This step is mainly applied to weak grid scenarios where grid voltage or frequency fluctuations are large and grid support capacity is insufficient, such as remote areas, isolated operation, or the initial stage of grid fault recovery. By operating the grid-connected converter as a voltage source, the wind turbine can actively adjust its output voltage and frequency, providing inertial response and voltage support to the grid, thereby improving system stability.

[0057] The technical benefits of this step lie in achieving seamless switching and stable operation of the grid-connected converter in grid-connected mode. This ensures that the wind turbine can maintain stable voltage and frequency at the grid connection point even under grid faults or weak grid conditions, thereby improving the grid-connection capability and system reliability of the wind turbine. Simultaneously, through coordinated control with the energy storage system, the power balance capability is further enhanced, providing key technical support for building a high-proportion renewable energy grid.

[0058] Further, step S3 includes: S31, by tracking the pre-synchronized voltage reference value and frequency reference value Generate an output control signal, in which the voltage reference value The calculation includes the grid voltage amplitude compensation term. and phase compensation terms ,satisfy and .

[0059] Specifically, in network configuration mode, this is achieved by tracking the pre-synchronized voltage reference value. and frequency reference value Generating output control signals is a crucial step in achieving stable grid-connected operation of wind turbines. This step, based on a dynamic compensation mechanism for grid voltage amplitude and phase, ensures that the grid-connected converter can respond quickly and seamlessly to changes in grid conditions after switching to grid-connected control, maintaining the stability of AC side voltage and frequency.

[0060] In this embodiment of the invention, the voltage reference value The generation includes two compensation terms: grid voltage amplitude compensation term. and phase compensation terms .in, Used to correct deviations in the mains voltage amplitude, bringing it closer to the rated voltage. ,and Used to adjust the phase of the grid-connected converter output voltage so that it is in phase with the grid voltage. Keep in sync. Specifically, , In practice, Typically, a PI controller is used to measure the real-time detected grid connection voltage. and The deviation is dynamically adjusted, and The phase of the power grid can be quickly tracked through a phase-locked loop (PLL) or phase feedforward control.

[0061] Furthermore, It is generally set to the rated voltage value of the power grid, such as (Three-phase line voltage) The adjustment range is usually in Within a certain range to avoid excessive voltage fluctuations affecting system stability. Phase compensation term. The response time should be controlled within Within this range, to ensure that the grid-connected converter can quickly adjust its output phase and maintain synchronization when the grid is disturbed.

[0062] This step is mainly applied to weak grid conditions where the grid strength is insufficient, such as sudden voltage drops, frequency fluctuations, or frequency change rates. Exceeding the set threshold In this situation, the wind turbine switches from grid-following mode to grid-connected mode, and the grid-side converter operates as a voltage source, achieving precise tracking. and This enables active support for voltage and frequency at the grid connection point, thereby improving grid stability.

[0063] The technical advantage of this step lies in achieving rapid response and seamless switching of the grid-connected converter in grid-connected mode by introducing amplitude and phase compensation mechanisms. This effectively suppresses voltage and current surges that may occur during mode switching, improving the reliability and dynamic performance of the system. Furthermore, this method has good adaptability and can be applied to grid-connected wind turbines with different power levels and energy storage configurations, demonstrating high engineering practical value.

[0064] S4, the synchronous control energy storage bidirectional converter adopts a feedforward PI control strategy to eliminate the deviation between the actual output power of the wind turbine and the load power demand, and achieve power balance support.

[0065] Specifically, in weak grid scenarios, the synchronous control energy storage bidirectional converter adopts a feedforward PI control strategy, the core objective of which is to eliminate the actual output power of the wind turbine. With load power requirements Deviation between This achieves power balance support. The control strategy introduces a feedforward loop to compensate for system dynamic response lag in advance, thereby improving the response speed and stability of the control system.

[0066] In this embodiment of the invention, the feedforward PI controller first collects the actual output power of the wind turbine. and load power requirements Calculate power deviation This deviation serves as the input to the PI controller, which adjusts the input based on a preset proportional gain. and integral gain Generate the power reference value for the energy storage bidirectional converter. Meanwhile, the feedforward circuit adjusts according to the rate of change of load power. Adjusting the output power of the energy storage system in advance reduces the system's hysteresis response to deviations. Feedforward gain The settings need to be optimized based on the system's inertial time constant and load fluctuation characteristics, typically in... Select within a range to ensure fast response without introducing overshoot.

[0067] Furthermore, the sampling frequency of the controller is generally set to To meet real-time control requirements. Integral time constant. Usually in Between, proportional gain Based on system bandwidth and stability requirements Adjustable within a specified range. Furthermore, the maximum charge / discharge power of the energy storage system... and minimum power As a limiting condition of the controller, it prevents the energy storage system from overloading or deep discharge.

[0068] Specifically, this control strategy is mainly applied to weak grid conditions with large fluctuations in grid voltage or frequency, such as grid faults, voltage drops, or frequency deviations. In this situation, the wind turbine switches to grid-connected mode, and the energy storage system compensates for the imbalance between the wind turbine's output power and load demand through rapid power response, thereby maintaining the stability of the grid-connected converter's output voltage and frequency and improving the system's support capability for the grid.

[0069] Furthermore, this feedforward PI control strategy significantly improves the dynamic response capability of the energy storage system in grid-connected mode, effectively suppresses the impact of power fluctuations on DC bus voltage, and enhances the autonomous adjustment capability of wind turbines under abnormal grid conditions. Through real-time elimination of power deviations, the system exhibits stronger robustness and stability, providing a key guarantee for the reliable operation of grid-connected wind turbines.

[0070] Further, step S4 includes: S41 adjusts the output power of the energy storage converter in real time through a feedforward PI controller to ensure the actual output power of the wind turbine. With load power requirements deviation Control precision reached Rated power.

[0071] Specifically, in a weak grid operation mode, this invention adjusts the output power of the energy storage converter in real time through a feedforward PI controller to achieve the actual output power of the wind turbine. With load power requirements Deviation between Control precision reached Rated power. This step is a key control step for grid-connected wind turbines to maintain stable system operation when the grid's support capacity decreases.

[0072] In this embodiment of the invention, the control strategy for the energy storage converter employs a fast PI control algorithm with feedforward compensation. The controller receives a power reference signal from the grid-connected co-controller. And combined with the real-time collected wind turbine output power With load power requirements Calculate power deviation The feedforward section is based on the load power requirements. The predicted value or instantaneous rate of change is compensated to improve the dynamic response speed; the PI part is based on the deviation. Integral and proportional regulation is performed to generate power commands for the energy storage converter. This drives the energy storage system to perform charging and discharging operations, thereby quickly balancing the power difference.

[0073] Furthermore, the control accuracy requirement of the controller is: Rated power, that is, the deviation at any given time. The absolute value should satisfy To achieve this level of accuracy, the parameters of the PI controller need to be tuned according to the dynamic characteristics of the system, typically the proportional gain. Settings Between, the integration time constant Settings Within a second range, to ensure fast system response and no overshoot. In addition, feedforward gain... Typically set to This enables direct tracking of load power requirements.

[0074] Specifically, this control strategy is mainly applied to emergency situations involving abnormal fluctuations in grid voltage or frequency, or a decline in grid support capacity. For example, when the grid frequency deviates from its rated value... And the rate of change Exceeding the set threshold When the system enters grid-connected mode, the energy storage system must immediately respond to power deviations to maintain the voltage source characteristics of the grid-connected converter. This control logic is applicable to wind turbines of different power levels and does not depend on specific hardware configurations, exhibiting good versatility and scalability.

[0075] This step, through high-precision power deviation control, ensures that the energy storage system can quickly and accurately compensate for the power difference between the wind turbine output and the load demand, thereby improving the system stability and responsiveness in grid-connected mode. Simultaneously, this control method effectively reduces the risk of power imbalance during mode switching and enhances the wind turbine's autonomous support capability under weak grid conditions, demonstrating significant engineering practical value.

[0076] S5, when the wind turbine is operating in grid-connected mode, monitors the state of charge of the energy storage system in real time. ,like Below the preset lower threshold Or higher than the preset upper limit threshold If this occurs, the energy storage system will be triggered to enter a degraded operation mode and an energy status warning signal will be sent.

[0077] Specifically, in grid-connected mode, wind turbines operate as voltage sources via grid-connected converters to maintain stable voltage and frequency at the grid connection point. Under this operating condition, the state of charge (SOC) of the energy storage system becomes a key parameter for system stability and energy management. The core of this step lies in real-time monitoring of the energy storage system's SOC and determining whether it exceeds a preset operating range. and This triggers the energy storage system to enter a degraded operation mode and issues an energy status warning signal.

[0078] In this embodiment of the invention, SOC monitoring is typically obtained through the battery management system (BMS) of the energy storage system. The calculation method is based on parameters such as the battery's open-circuit voltage (OCV), internal resistance, and historical charge-discharge curves, and estimates are performed using algorithms such as the ampere-hour integration method or Kalman filtering. In grid-connected mode, the energy storage system needs to have rapid response capabilities to compensate for fluctuations in wind turbine output power. Therefore, the SOC sampling frequency should be no less than 100ms to ensure the real-time performance of the control system. When the SOC is lower than... (For example, set to 20%) or higher When the capacity is set to 90%, the grid-connected controller will determine that the energy storage system has entered an energy-constrained state. At this time, it will trigger the degraded operation mode of the energy storage converter to limit its maximum charging and discharging power, prevent the battery from being overcharged or over-discharged, thereby extending its service life and ensuring system safety.

[0079] Furthermore, and The settings need to be optimized based on factors such as battery type (e.g., lithium iron phosphate battery, ternary lithium battery), operating temperature, and cycle life requirements. For example, for lithium iron phosphate batteries, a SOC operating range of 20% to 90% is generally recommended to avoid damage to battery performance from deep discharge and overcharging. Warning signals can be sent via standard Modbus or CAN bus protocols, and the signal content includes the current SOC value, threshold status, and warning level, facilitating response and processing by the main control system or remote monitoring platform.

[0080] Specifically, this step mainly applies to scenarios where wind turbines switch to grid-connected operation mode under grid fault or weak grid conditions. In this situation, the energy storage system undertakes the power balancing task, and the stability of its State of Charge (SOC) directly affects the sustainability of its grid-connected capability. If the energy storage system cannot provide sufficient power support due to abnormal SOC, it will cause voltage or frequency fluctuations at the grid connection point, affecting the stability of the entire system. Therefore, this early warning mechanism can effectively prevent system instability or equipment damage caused by abnormal energy state of the energy storage system in actual operation.

[0081] This step, by introducing a State of Charge (SOC) threshold judgment mechanism, enables dynamic operation management of the energy storage system in grid-connected mode. When SOC is abnormal, the system can promptly downgrade the energy storage operation mode to avoid battery overload or capacity degradation. Simultaneously, by sending early warning signals, it provides decision-making basis for the main control system, thereby improving the operational reliability and safety of wind turbines in complex grid environments. This mechanism is a crucial guarantee for achieving wind-storage coordinated grid-connected control, demonstrating the innovation and practicality of this invention in system stability and energy management.

[0082] The collaborative control method for grid-connected wind turbine operation mode of this invention improves the operational safety and system stability of wind turbines under abnormal energy storage conditions by real-time monitoring of the state of charge of the energy storage system and triggering a degraded operation mode and early warning mechanism in grid-connected mode, thereby extending the service life of the energy storage system and optimizing energy management strategies.

[0083] Example 2 This embodiment relates to a collaborative control method for the operation mode of a grid-connected wind turbine. For example... Figure 2 As shown, this method is executed by a control system consisting of a wind turbine main controller, a grid-connected coordination controller, a grid-connected wind power converter controller, and an energy storage bidirectional converter controller. The grid-connected coordination controller serves as the decision-making and coordination center. Specifically, the method includes the following steps: First, the voltage at the grid connection point is collected in real time. and frequency And calculate the rate of change of frequency. .like Figure 3 As shown, when the grid connection point voltage Voltage below the set grid connection point low threshold And the duration exceeds If the grid strength is insufficient, it is determined that the power grid strength is insufficient; or if the absolute value of the deviation between the frequency collected at the grid connection point and the rated frequency is... Exceeding the set grid connection point frequency deviation threshold And the absolute value of the rate of change of frequency Exceeding the set threshold for the rate of change of frequency If the power grid strength is insufficient, then it is determined that the power grid strength is insufficient.

[0084] Furthermore, such as Figure 4 As shown, when insufficient grid strength is detected, the wind turbine's operating mode switches from grid-following mode to grid-connecting mode; once the grid strength recovers and stabilizes for a period of time... Afterwards, the wind turbine's operating mode was switched back from grid-connected mode to grid-connected mode.

[0085] Specifically, in a strong power grid scenario, the wind turbines operate in grid-following mode. The grid-side converters employ phase-locked loop (PLL)-based vector control to decouple active and reactive power control, with active power operating according to dispatch instructions or tracking the turbine's power curve. The energy storage converter uses DC voltage-power droop control. The allowable DC voltage target range is set to... Voltage When the power of the wind turbine increases due to fluctuations, the energy storage automatically increases its charging power; when During descent, the discharge power is automatically increased, thereby achieving smooth adjustment of the wind turbine's output power.

[0086] In weak power grid scenarios, such as Figure 5 As shown, when a wind turbine switches from grid-connected mode to grid-connected mode, the modulation signal of the grid-connected converter remains unchanged at the moment of switching. The grid-connected converter's grid-connected control algorithm is then switched to the grid-connected control algorithm. This algorithm calculates the output voltage reference value required to maintain the rated voltage and frequency based on the real-time current detected by the grid connection, and generates a new modulation wave signal according to the grid-connected control algorithm, achieving a seamless switching. When the wind turbine operates in grid-connected mode, the grid-connected converter acts as a voltage source, tracking the voltage reference value generated by the grid-connected control algorithm. and frequency reference value and At this time, the energy storage converter uses a fast PI controller with feedforward to control the load power on the demand side. Actual output power of the fan deviation The value is zero, which essentially means that the energy storage system bears the entire power difference, ensuring that the grid-connected converter has a stable grid support capability.

[0087] Example 3 This invention also provides a collaborative control device for the operation mode of grid-connected wind turbine generators, such as... Figure 6 As shown, the device 10 includes: The power grid status monitoring module 100 is used to collect the voltage, frequency and rate of change of the grid connection point in real time, and to determine whether the power grid strength is insufficient based on multi-dimensional power grid status parameters. The mode switching control module 200 is used to execute a three-stage mode switching strategy of hold-switching-update when the grid strength is determined to be insufficient. In this strategy, the modulation wave of the grid-connected converter is kept unchanged at the moment of switching, and then the control algorithm is switched and the grid construction control parameters are pre-synchronized to generate a new modulation wave signal. The voltage source control module 300 is used to control the grid-connected converter to operate as a voltage source in grid-connected mode, and generates output control signals based on the pre-synchronized voltage reference value and frequency reference value. The energy storage power balance module 400 is used to synchronously control the bidirectional energy storage converter using a feedforward PI control strategy to eliminate the deviation between the actual output power of the wind turbine and the load power demand, thereby achieving power balance support.

[0088] Example 4 To implement the methods of the above embodiments, the present invention also provides a computer device, which includes a memory and a processor; wherein the processor runs a program corresponding to the executable program code by reading executable program code stored in the memory, so as to implement the various steps of the methods described above.

[0089] Example 5 To implement the above embodiments, this application also proposes a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the method described in the foregoing embodiments.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0091] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0092] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

Claims

1. A collaborative control method for the operation mode of a grid-connected wind turbine generator, characterized in that, Includes the following steps: S1 collects the voltage, frequency and rate of change of the grid connection point in real time, and determines whether the grid strength is insufficient based on multi-dimensional grid state parameters. S2, when the grid strength is determined to be insufficient, a three-stage mode switching strategy of hold-switching-update is executed. During the switching moment, the modulation wave of the grid-connected converter is kept unchanged, and then the control algorithm is switched and the grid construction control parameters are pre-synchronized to generate a new modulation wave signal. S3 controls the grid-connected converter to operate as a voltage source in grid-connected mode, generating an output control signal based on the pre-synchronized voltage reference value and frequency reference value. S4, the synchronous control energy storage bidirectional converter adopts a feedforward PI control strategy to eliminate the deviation between the actual output power of the wind turbine and the load power demand, and achieve power balance support.

2. The method according to claim 1, characterized in that, The method of real-time acquisition of grid connection point voltage, frequency, and their rate of change, and determination of whether the grid strength is insufficient based on multi-dimensional grid state parameters, also includes: S11, when the grid connection point voltage Voltage below the set grid connection point low threshold And the duration exceeds At that time, the power grid strength was determined to be insufficient; S12, when the absolute value of the deviation between the sampling frequency at the grid connection point and the rated frequency is... Exceeding the set grid connection point frequency deviation threshold And the absolute value of the rate of change of frequency Exceeding the set threshold for the rate of change of frequency At that time, the power grid strength was determined to be insufficient.

3. The method according to claim 1, characterized in that, The three-stage mode switching strategy of execution of retain-switch-update also includes: S21, calculate the reference value of the output voltage required to maintain the rated voltage and frequency based on the real-time current detected by grid connection. and frequency reference value The formula for calculating the voltage reference value is as follows: The formula for calculating the frequency reference value is: , and This is the preset scaling factor.

4. The method according to claim 1, characterized in that, The control of the grid-connected converter to operate as a voltage source in grid-connected mode also includes: S31, by tracking the pre-synchronized voltage reference value and frequency reference value Generate an output control signal, in which the voltage reference value The calculation includes the grid voltage amplitude compensation term. and phase compensation terms ,satisfy and .

5. The method according to claim 1, characterized in that, The synchronous control energy storage bidirectional converter adopts a feedforward PI control strategy and also includes: S41 adjusts the output power of the energy storage converter in real time through a feedforward PI controller to ensure the actual output power of the wind turbine. With load power requirements deviation Control precision reached Rated power.

6. The method according to claim 1, characterized in that, Also includes: S5, when the wind turbine is operating in grid-connected mode, monitors the state of charge of the energy storage system in real time. ,like Below the preset lower threshold Or higher than the preset upper limit threshold If this occurs, the energy storage system will be triggered to enter a degraded operation mode and an energy status warning signal will be sent.

7. A collaborative control device for the operation mode of a grid-connected wind turbine generator, characterized in that, include: The power grid status monitoring module is used to collect the voltage, frequency and rate of change of the grid connection point in real time, and to determine whether the power grid strength is insufficient based on multi-dimensional power grid status parameters. The mode switching control module is used to execute a three-stage mode switching strategy of hold-switching-update when the grid strength is determined to be insufficient. During the switching moment, the modulated wave of the grid-connected converter is kept unchanged. Then, the control algorithm is switched and the grid construction control parameters are pre-synchronized to generate a new modulated wave signal. The voltage source control module is used to control the grid-connected converter to operate as a voltage source in grid-connected mode, and generates output control signals based on the pre-synchronized voltage reference value and frequency reference value; The energy storage power balancing module is used to synchronously control the bidirectional energy storage converter using a feedforward PI control strategy to eliminate the deviation between the actual output power of the wind turbine and the load power demand, thereby achieving power balance support.

8. A computer device, characterized in that, Including processor and memory; The processor reads executable program code stored in the memory to run a program corresponding to the executable program code, so as to implement a collaborative control method for the operation mode of a grid-connected wind turbine as described in any one of claims 1-6.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements a collaborative control method for the operation mode of a grid-type wind turbine as described in any one of claims 1-6.

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