Method and device for controlling non-energy-storage type networking wind turbine generator based on master control following variable flow regulation

Abstract

The invention provides a control method and device for a non-energy-storage type grid-forming wind turbine generator based on main control following variable current regulation. The device comprises a main controller, a machine side converter and a grid side converter, wherein the machine side converter and the grid side converter are connected with the main controller. The thought that the direct-current bus voltage is controlled on the machine side and the fan power is controlled on the grid side is adopted, the power is issued to the master control through the converter, the master control achieves electromagnetic and mechanical balance by rapidly adjusting the variable pitch, and the problem that the reserved power cannot be provided for coping with primary frequency modulation when the direct-current bus voltage is controlled through a traditional grid-side converter is solved; the millisecond-level primary frequency modulation action under the wind speed change is achieved, and the millisecond-level fan black start is achieved under the no-load condition.

Description

Technical Field

[0001] The present invention relates to the field of grid-forming functions of wind turbine power stations, and in particular to a control method and device for a non-energy storage type grid-forming wind turbine set with a main control following current conversion regulation. Background Art

[0002] With the large-scale access of wind turbines, the characteristics of the power grid showing "double highs", "double new" and "double peaks" are further highlighted. The high proportion of wind turbine access will have an impact on the stability of the power grid that cannot be ignored. Since the active and reactive power of the wind turbine adopts the phase angle and voltage of the power grid, it is equivalent to only controlling the amplitude of the current sent to the power grid and its phase relative to the voltage, so the new energy unit is often called a current source. At present, traditional new energy units all adopt the "current source mode" and cannot build a 100% new energy system. They are often unable to support the power grid in a low short-circuit ratio and weak AC system, resulting in frequency and voltage collapse, power oscillation, and unit disconnection from the grid.

[0003] Therefore, in order to improve the low inertia, strong fluctuation, and weak support grid-connected characteristics of traditional new energy wind turbines, the power generation grid-connected technology needs to change from the "passive adaptation" grid-following type to the "active support" grid-building type. Grid-building wind turbines are units that can independently build a power grid, and grid-building wind turbines based on the "voltage source mode" can effectively solve the above problems. Therefore, many projects have proposed an engineering grid-building control algorithm based on a DC capacitor inertia synchronization control strategy, and effectively considered the problem of small DC bus capacitance, while this strategy still uses the traditional control architecture of the inverter following the main control.

[0004] Although the above strategy retains the existing architecture of the wind turbine and utilizes the DC bus control characteristics, it has two defects: first, the startup process still requires the large power grid to assist it in establishing the DC bus voltage, resulting in the inability of the direct-drive wind turbine to achieve the black start function; second, the active power is still given by the main control according to the wind conditions and the status of the whole machine, and the main control fails to respond to the frequency disturbance and the need to increase the active power, resulting in the wind turbine primary frequency regulation function cannot be realized at the wind turbine port, and the active support capacity only has the inertia support effect, and the crowbar is easy to move and stop when running independently. Therefore, at this stage, the non-energy storage wind power technology route that adopts the DC capacitor inertia synchronous control strategy often only has active support capabilities and lacks the ability to truly independently build a real large power grid. Summary of the invention

[0005] In order to solve the above-mentioned problems, the present invention proposes a control method and device for a wind turbine set with a non-energy storage structure in which the main control follows the inverter regulation. The method adopts the idea of ​​controlling the DC bus voltage on the machine side and controlling the wind turbine power on the grid side, and transmits power to the main controller through the inverter. The main controller achieves electromagnetic and mechanical balance by quickly adjusting the pitch.

[0006] A control device for a wind turbine generator set without energy storage and with master control following current conversion regulation comprises: a main controller, a machine-side converter connected to the main controller, and a grid-side converter; the main controller is used to:

[0007] Start the wind turbine generator set and, through the pitch operation, make the impeller of the wind turbine generator set start to absorb wind energy and drive the speed of the wind turbine generator to increase continuously;

[0008] When the speed of the wind turbine generator reaches the set grid-connected speed, the machine-side converter is started, and the machine-side converter is controlled to stabilize the DC bus voltage at the set rated voltage;

[0009] When the DC bus voltage is stable, starting the grid-side converter, and controlling the output current of the grid-side converter by adopting a virtual synchronous control mode;

[0010] The output power of the network side port is detected and received, and the pitch is changed in real time according to the output power of the network side port so that the output power of the network side port is maintained at the target power.

[0011] Furthermore, the main controller includes a torque deviation limit adjustment module, an off-grid operation stability control module, a machine-side converter control module and a grid-side converter control module respectively connected to the machine-side converter and the grid-side converter.

[0012] Furthermore, the machine-side converter control module includes:

[0013] A machine-side converter starting unit, used for starting the machine-side converter after the generator speed reaches a grid-connected speed;

[0014] A DC bus voltage detection unit, used for real-time detection of the DC bus voltage;

[0015] The electric energy flow control unit is used to control the machine-side converter to make electric energy flow from the wind turbine to the DC bus so as to increase the DC bus voltage when the DC bus voltage is lower than the rated voltage; and to control the machine-side converter to make electric energy flow from the DC bus to the wind turbine so as to reduce the DC bus voltage when the DC bus voltage is higher than the rated voltage.

[0016] Furthermore, the grid-side converter control module includes:

[0017] A grid-side converter starting unit, used for starting the grid-side converter after the DC bus voltage is stabilized;

[0018] A grid-side port voltage detection unit, used for real-time detection of grid-side port voltage;

[0019] An output current control unit is used to control the grid-side converter to increase the output current setting value and detect the actual output current when it is detected that the grid-side port voltage is less than the nominal voltage. If the actual output current is less than the output current setting value, the grid-side converter is controlled to increase the current output; if the actual output current is greater than the output current setting value, the grid-side converter is controlled to output a small current, so that the actual output current is equal to the output current setting value in the end; when it is detected that the grid-side port voltage is greater than the nominal voltage, the grid-side converter is controlled to reduce the output current setting value, and the actual output current is detected. If the actual output current is less than the output current setting value, the grid-side converter is controlled to increase the current output; if the actual output current is greater than the output current setting value, the controlled grid-side converter is controlled to reduce the current output, so that the actual output current is equal to the output current setting value in the end;

[0020] The output power detection unit is used to detect the output power of the network side port and feed back the detected output power of the network side port to the main controller.

[0021] Furthermore, the torque deviation limit adjustment module is used to trigger the inertia frequency regulation demand, set the INER_FM flag, and increase the torque deviation limit to 15% when a grid frequency disturbance is detected. The adjusted torque deviation limit is transmitted by the main controller to the machine-side converter control module. The machine-side converter control module dynamically adjusts the torque control according to the updated torque deviation limit to ensure the inertia response capability of the generator under frequency fluctuations.

[0022] Furthermore, the off-grid operation stability control module is used to set the off-grid operation flag PRI_FM when the converter detects the off-grid operation state. After receiving the off-grid operation flag, the main controller uses the power value fed back by the converter in real time as the current power set value, and transmits this updated power set value back to the converter to ensure smooth operation of torque and speed in the off-grid state.

[0023] Furthermore, the off-grid operation state is that the difference between the main control given power and the converter feedback power exceeds a preset limit.

[0024] A control method for a non-energy storage type grid-connected wind turbine set with master control following current conversion regulation is implemented by using the above device, and the method comprises the following steps:

[0025] Start the wind turbine generator set and, through the pitch operation, make the impeller of the wind turbine generator set start to absorb wind energy and drive the speed of the wind turbine generator to increase continuously;

[0026] When the speed of the wind turbine generator reaches the set grid-connected speed, the machine-side converter is started, and the machine-side converter is controlled to stabilize the DC bus voltage at the set rated voltage;

[0027] When the DC bus voltage is stable, the grid-side converter is started, the output current of the grid-side converter is controlled by a virtual synchronous control mode, and the output power of the grid-side port is detected and received;

[0028] The main controller performs real-time pitch change according to the output power of the grid-side port so as to maintain the output power of the grid-side port at a target power.

[0029] Further, the main controller performs real-time pitch change according to the output power of the grid-side port so that the output power of the grid-side port is maintained at the target power, specifically including:

[0030] When the main controller detects a grid frequency disturbance, it triggers an inertia frequency regulation demand, sets the INER_FM flag, and increases the torque deviation limit to 15%. The adjusted torque deviation limit is transmitted from the main controller to the machine-side converter control module, and the machine-side converter control module dynamically adjusts the torque control according to the updated torque deviation limit to ensure the inertia response capability of the generator under frequency fluctuations.

[0031] When the converter detects the off-grid operation state, the off-grid operation flag PRI_FM is set. After receiving the off-grid operation flag, the main controller uses the power value fed back by the converter in real time as the current power set value, and transmits this updated power set value back to the converter to ensure the smooth operation of torque and speed in the off-grid state.

[0032] Beneficial effects: Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention uses the switch-side grid-side converter control target to propose a strategy for feeding back the power that the converter should actually output to the main control, thereby realizing mechanical-electromagnetic closed-loop control, solving the problem that the traditional grid-side converter controls the DC bus voltage and cannot provide reserved power to cope with primary frequency modulation, realizing millisecond-level primary frequency modulation action under frequency disturbance conditions, and achieving millisecond-level wind turbine black start under no-load conditions. The present invention can control wind turbines and has grid-building performance, can be used in 100% new energy new power systems, and has the ability to support system voltage and frequency. The present invention combines the conventional rotor motion equations in virtual synchronous power generation technology to provide a grid-building wind turbine control strategy that can be applied in engineering applications. The effectiveness of the present invention has been proven by conducting experiments and verifications in actual engineering projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a control block diagram of a machine-side converter according to an embodiment of the present invention;

[0035] Figure 2 It is an overall timing diagram of an embodiment of the present invention;

[0036] Figure 3This is a fixed value modification diagram for an embodiment of the present invention;

[0037] Figure 4 This is a control block diagram of a grid-side converter according to an embodiment of the present invention;

[0038] Figure 5 It is a semi-physical simulation verification of the energy storage-free grid-type wind turbine unit according to the embodiment of the present invention;

[0039] Figure 6 This is a model of a grid-type wind turbine unit without energy storage according to an embodiment of the present invention;

[0040] Figure 7 The voltage change dynamic response curve under wind speed change according to the embodiment of the present invention;

[0041] Figure 8 The mechanical power and wind energy utilization coefficient curve under wind speed changes of the embodiment of the present invention;

[0042] Fig. 9 The active power output waveform of the wind turbine according to the embodiment of the present invention;

[0043] Fig.10 The reactive power output waveform of the wind turbine according to the embodiment of the present invention;

[0044] Fig.11 This is the output waveform of the DC capacitor of the fan according to the embodiment of the present invention;

[0045] Fig.12 This is the on-site 35kV line test waveform of the embodiment of the present invention;

[0046] Fig.13 This is the on-site machine-side experimental waveform of the embodiment of the present invention;

[0047] Fig.14 The present invention is a schematic structural diagram of a control device for a wind turbine generator set without energy storage in a master-control-following inverter-regulated manner according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to more clearly explain the purpose, technical solutions and advantages of the embodiments of the present invention, the present invention will provide a detailed and comprehensive description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. It should be pointed out that the described embodiment is only one of the examples of the present invention, not the only or all embodiments. Without performing creative work, those skilled in the art can easily derive other embodiments based on the technical content disclosed in the present invention, and these embodiments also belong to the protection scope of the present invention.

[0049] On the one hand, the present invention needs to completely change the existing converter technology division framework, placing the DC bus voltage control function on the machine side converter and the power control on the grid side converter (such as Fig.14On the other hand, it is necessary to upgrade and transform the main control speed regulation algorithm and coordinate with the change of the converter framework to adapt to the imbalance of mechanical and electromagnetic power caused by the electromagnetic power fluctuation formed by the DC bus voltage on the machine side.

[0050] The present invention proposes a subversive control architecture idea in which the main control cooperates with the inverter, instead of the traditional inverter cooperating with the main control in the independent networking mode. That is, the power setting is no longer achieved by the main control only looking up the wind speed table, but the power that the inverter should actually output is fed back to the main control, thereby realizing a true closed loop.

[0051] In order to achieve the above object, the present invention adopts the following technical solution:

[0052] (1) Machine-side control

[0053] The machine-side converter is used to stabilize the DC side voltage. The DC bus voltage outer loop outputs the quadrature axis current reference value, and the two current inner loops output the DC and quadrature axis voltage reference values. After coordinate transformation and PWM generator, the signal used to trigger the converter switch device is obtained. The control block diagram of the machine-side converter is shown in the figure. Figure 1 shown.

[0054] When the deviation between the given power and the actual power is within a certain range, it is considered that the converter can follow the main control power to a certain extent, and is in a grid-connected operation state, or an off-grid operation state (at this time, the load power is closer to the given power of the main control, and the frequency is near the rated value). When the deviation between the given power and the actual power exceeds the range, it is considered that the converter power cannot follow the main control power and is in an off-grid operation state. At this time, the load power differs greatly from the given power of the main control, in order to prevent the given power of the main control from continuing to change monotonically in a certain direction. At this time, the given power of the main control needs to be specially processed, such as limiting, maintaining the given value unchanged, assigning the actual value to the given value, or the converter clears the given value of the main control and does not respond to the given power of the main control.

[0055] In order to solve the problem of abnormal torque and speed changes caused by the converter not following the main control power command during off-grid operation, the converter and main control need to be modified as follows:

[0056] Inverter modification: Determine the off-grid operation flag and transmit it to the main control. The condition for setting the off-grid operation flag is that the difference between the power sent by the main control and the power fed back by the inverter exceeds a certain limit (tentatively set to 300kW, 200ms).

[0057] Master control modification: After receiving the off-grid operation flag of the converter, the power feedback value uploaded by the converter in real time is used as the power given value.

[0058] The overall timing is as follows Figure 2 shown.

[0059] The initial power setting and power feedback follow each other. When the power feedback does not follow the power setting, the converter determines the off-grid operation flag. When the off-grid operation flag is set and transmitted to the main control, the main control uses the power feedback value as the power setting value. From then on, the power setting value follows the power feedback value.

[0060] In order to increase the maximum limit of torque deviation, the present invention makes the following modifications:

[0061] Figure 3 The INER_FM inertia frequency modulation flag remains unchanged. When the main control receives the INER_FM inertia frequency modulation flag as 1, the limit of the torque deviation fault is increased from 7% to 15%. At the same time, there is no need to issue the frequency modulation power command value consistent with the traditional grid-following type. This step is specifically implemented by the torque deviation limit adjustment module. The torque deviation limit adjustment module is used to trigger the inertia frequency modulation demand when the grid frequency disturbance is detected, set the INER_FM flag, and increase the torque deviation limit to 15%. The adjusted torque deviation limit is transmitted from the main controller to the machine-side converter control module. The machine-side converter control module dynamically adjusts the torque control according to the updated torque deviation limit to ensure the inertia response capability of the generator under frequency fluctuations.

[0062] Figure 3 When the converter detects the off-grid operation state, the off-grid operation stability control module modifies PRI_FM to the off-grid operation flag. When the main control receives the PRI_FM off-grid operation flag as 1, the power value fed back by the converter in real time is used as the current power given value, and the updated power given value is transmitted back to the converter to ensure the smooth operation of torque and speed in the off-grid state.

[0063] (2) Grid-side control

[0064] The active-frequency dynamic characteristics of the grid-side virtual synchronous generator are realized through the virtual speed regulator, and the reactive-voltage droop control obtains the output voltage of the grid-side virtual synchronous generator. The virtual synchronous control controls the active and reactive power output of the wind turbine through active-frequency control and reactive-voltage control, while simulating the characteristics of the synchronous generator. Figure 4 This is the specific control block diagram of virtual synchronization control on the PMSG wind power grid side.

[0065] The virtual speed regulator is controlled by a proportional regulator, the command is the rated angular frequency, and the feedback frequency is the angular frequency of its own output. The sum of the frequency difference and the power difference is the output angular frequency after passing through the first-order inertial damping link and adding the frequency feedforward. The angular frequency is integrated to obtain the synchronous rotation coordinate transformation angle.

[0066] Reactive power-voltage droop control is the difference between reactive power command and actual power after droop coefficient plus rated voltage command output voltage value, and its value is given as voltage loop. Among them, reactive power is filtered by low-pass filter.

[0067]

[0068] Where ω is the inverter output angular frequency amplitude command, θ is the inverter output phase, ω0 is the inverter output angular frequency, and J is the virtual inertia. m is the mechanical power of the fan, P e is the electromagnetic power of the fan, and D is the damping coefficient. The expression of the additional power control of the fan ΔP is:

[0069]

[0070] In the above formula, K p is the proportional regulation coefficient, and ΔP is the additional power of the fan.

[0071] In the above overall control strategy, reactive power-voltage droop can be expressed as:

[0072]

[0073] In the formula, K q is the reactive power-voltage droop coefficient, Q e and Q ref are the reactive power and reactive power reference value of the grid connection point, ΔU is the change of the voltage value of the grid connection point, and U n The dual-loop control strategy and active power technology in the grid-side control are consistent with other traditional inverter algorithms, so the present invention will not elaborate on them in detail.

[0074] In order to verify the practicality and effectiveness of the above strategy, the present invention carries out simulation verification, the specific contents are as follows:

[0075] Case 1 uses the RT-LAB test platform for testing. RT-LAB builds a simulation model for operation verification and runs the software programs required for the corresponding wind turbine, such as Figure 5 As shown in the figure. The left side is the wind turbine inverter, and the right side is the RT-LAB semi-physical simulation platform. Figure 6 As shown in the figure, it is a grid-type wind turbine model without energy storage.

[0076] The simulation duration is 4s. The access load is P L =200kW; wind speed decreases from 12m / s to 8m / s in 1s; Figure 7 The left half shows the change in wind speed, and the right half shows the change in voltage. Figure 8 The left side is the mechanical power change curve. Figure 8 The right side shows the changing curve of wind energy utilization coefficient.

[0077] From the waveform, it can be seen that the wind turbine has voltage stability under this control strategy, and the mechanical power and wind energy utilization coefficient can remain stable under wind speed changes. The active power can be controlled by fixed-current control, and the wind turbine control strategy has achieved the ideal effect. Combined with the on-site main wiring, the simulation waveform is as follows Figure 9-11 As shown. After the power matching of the main control unit, the active power reaches a stable value of 0.55kW in 35 seconds, and the reactive power reaches 1.03kVar. The DC bus capacitor is stable at 1070V.

[0078] (1) Field test simulation verification

[0079] Case 2 is from a field project demonstration. The project is from central Hubei Province. After the on-site wind farm was modified according to this strategy, the test data is as follows: Fig.12 shown.

[0080] Fig.12 The third line from top to bottom in the upper middle is the output frequency of the 35kV line in the field, and the frequency is maintained at 50Hz. The seventh line is the output voltage, the first line is the output active power, and the fifth line is the reactive power. The following lines have all reached a continuous stable state without long-term oscillation.

[0081] Fig.13 The first line in the upper middle is the frequency waveform, which is maintained at 50Hz. The second line from top to bottom is the voltage waveform, the fourth line is the wind turbine reactive power waveform, and the third line is the wind turbine active power waveform. Fig.13 The flexible controllability of the grid-type wind turbine unit in reactive power voltage regulation is given. The above results effectively prove the advantages of the technology of the present invention in wind turbine grids.

[0082] The traditional wind turbine grid control algorithm based on the DC capacitor inertia synchronous control strategy cannot achieve primary frequency regulation and black start on the machine side in engineering. Therefore, the present invention proposes a control method and device for a non-energy storage type grid-connected wind turbine set with main control following inverter regulation, which mainly includes: a modified main controller, a machine-side converter, and a grid-side converter. The present invention adopts the idea of ​​controlling the DC bus voltage on the machine side and the wind turbine power on the grid side, and sends power to the main control through the converter. The main control achieves electromagnetic and mechanical balance by quickly adjusting the pitch.

[0083] The present invention solves the problem that the traditional grid-side converter cannot provide reserved power to cope with the primary frequency modulation when controlling the DC bus voltage, realizes the millisecond-level primary frequency modulation action under wind speed changes, and achieves millisecond-level wind turbine black start under no-load conditions. This strategy has been successfully applied in a certain actual project, and the actual field waveform data proves the effectiveness of the present invention. Through the control algorithm and device system proposed in the present invention, the wind turbine power supply grid performance can be realized, a 100% new energy new power system can be constructed, and the system frequency and voltage can be stably supported.

[0084] The specific embodiments of the present invention are as described above, but please note that the protection scope of the present invention is not limited thereto. Any person with ordinary skills in the technical field can easily think of other changes or alternatives within the technical scope disclosed in the present invention, and these changes or alternatives should also be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the scope defined in the claims.

Claims

1. A control device for wind turbines without energy storage and with master control following current conversion regulation, characterized in that: include: A main controller, a machine-side converter connected to the main controller, and a grid-side converter; the main controller is used for: Start the wind turbine generator set and, through the pitch operation, make the impeller of the wind turbine generator set start to absorb wind energy and drive the speed of the wind turbine generator to increase continuously; When the speed of the wind turbine generator reaches the set grid-connected speed, the machine-side converter is started, and the machine-side converter is controlled to stabilize the DC bus voltage at the set rated voltage; When the DC bus voltage is stable, starting the grid-side converter, and controlling the output current of the grid-side converter by adopting a virtual synchronous control mode; The output power of the network side port is detected and received, and the pitch is changed in real time according to the output power of the network side port so that the output power of the network side port is maintained at the target power.

2. The control device for wind turbine generator set without energy storage and with master control following current conversion regulation as claimed in claim 1 is characterized in that: The main controller includes a torque deviation limit adjustment module, an off-grid operation stability control module, a machine-side converter control module and a grid-side converter control module respectively connected to the machine-side converter and the grid-side converter. Torque deviation limit adjustment module.

3. The control device for wind turbine generator set without energy storage and with master control following current conversion regulation as claimed in claim 2 is characterized in that: The machine-side converter control module comprises: A machine-side converter starting unit, used for starting the machine-side converter after the generator speed reaches a grid-connected speed; A DC bus voltage detection unit, used for real-time detection of the DC bus voltage; The electric energy flow control unit is used to control the machine-side converter to make electric energy flow from the wind turbine to the DC bus so as to increase the DC bus voltage when the DC bus voltage is lower than the rated voltage; and to control the machine-side converter to make electric energy flow from the DC bus to the wind turbine so as to reduce the DC bus voltage when the DC bus voltage is higher than the rated voltage.

4. The control device for wind turbine generator set without energy storage and with master control following current conversion regulation as claimed in claim 2 is characterized in that: The grid-side converter control module comprises: A grid-side converter starting unit, used for starting the grid-side converter after the DC bus voltage is stabilized; A grid-side port voltage detection unit, used for real-time detection of grid-side port voltage; An output current control unit is used to control the grid-side converter to increase the output current setting value and detect the actual output current when it is detected that the grid-side port voltage is less than the nominal voltage. If the actual output current is less than the output current setting value, the grid-side converter is controlled to increase the current output; if the actual output current is greater than the output current setting value, the grid-side converter is controlled to output a small current, so that the actual output current is equal to the output current setting value in the end; when it is detected that the grid-side port voltage is greater than the nominal voltage, the grid-side converter is controlled to reduce the output current setting value, and the actual output current is detected. If the actual output current is less than the output current setting value, the grid-side converter is controlled to increase the current output; if the actual output current is greater than the output current setting value, the controlled grid-side converter is controlled to reduce the current output, so that the actual output current is equal to the output current setting value in the end; The output power detection unit is used to detect the output power of the network side port and feed back the detected output power of the network side port to the main controller.

5. The control device for wind turbine generator set without energy storage and with master control following current conversion regulation as claimed in claim 2 is characterized in that: The torque deviation limit adjustment module is used to trigger the inertia frequency regulation demand, set the INER_FM flag, and increase the torque deviation limit to 15% when a grid frequency disturbance is detected. The adjusted torque deviation limit is transmitted to the machine-side converter control module by the main controller. The machine-side converter control module dynamically adjusts the torque control according to the updated torque deviation limit to ensure the inertia response capability of the generator under frequency fluctuations.

6. The control device for wind turbine generator set without energy storage and with master control following current conversion regulation as claimed in claim 2, characterized in that: The off-grid operation stability control module is used to set the off-grid operation flag PRI_FM when the converter detects the off-grid operation state. After receiving the off-grid operation flag, the main controller uses the power value fed back by the converter in real time as the current power set value, and transmits this updated power set value back to the converter to ensure the smooth operation of torque and speed in the off-grid state.

7. The control device for wind turbine generator set without energy storage and with master control following current conversion regulation as claimed in claim 6 is characterized in that: The off-grid operation state is that the difference between the main control given power and the converter feedback power exceeds a preset limit.

8. A control method for a wind turbine generator set without energy storage with main control following current conversion regulation, characterized in that: The method is carried out using the device as described in any one of claims 1 to 7, and comprises the following steps: Start the wind turbine generator set and, through the pitch operation, make the impeller of the wind turbine generator set start to absorb wind energy and drive the speed of the wind turbine generator to increase continuously; When the speed of the wind turbine generator reaches the set grid-connected speed, the machine-side converter is started, and the machine-side converter is controlled to stabilize the DC bus voltage at the set rated voltage; When the DC bus voltage is stable, the grid-side converter is started, the output current of the grid-side converter is controlled by a virtual synchronous control mode, and the output power of the grid-side port is detected and received; The main controller performs real-time pitch change according to the output power of the grid-side port so as to maintain the output power of the grid-side port at a target power.

9. The control method for wind turbine generator set without energy storage with master control following current conversion regulation as claimed in claim 8 is characterized in that: The main controller performs real-time pitch change according to the output power of the grid-side port so that the output power of the grid-side port is maintained at the target power, specifically including: When the main controller detects a grid frequency disturbance, it triggers an inertia frequency regulation demand, sets the INER_FM flag, and increases the torque deviation limit to 15%. The adjusted torque deviation limit is transmitted from the main controller to the machine-side converter control module, and the machine-side converter control module dynamically adjusts the torque control according to the updated torque deviation limit to ensure the inertia response capability of the generator under frequency fluctuations. When the converter detects the off-grid operation state, the off-grid operation flag PRI_FM is set. After receiving the off-grid operation flag, the main controller uses the power value fed back by the converter in real time as the current power set value, and transmits this updated power set value back to the converter to ensure smooth operation of torque and speed in the off-grid state.

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