Networking type wind power converter hybrid synchronous control system and control method

Abstract

The invention relates to a hybrid synchronous control system and control method for a network construction type wind power converter. The control system comprises an active droop control module, a transient active control module, an active frequency control module, a hybrid synchronous control module, a system frequency control module and a phase-locked integral control module. According to the control method, the wind power converter rated frequency omega N and the wind power converter networking frequency omega are subtracted and then are connected with the droop controller, and the output of the droop controller is droop power. The method has the advantages that the transient active control module and the hybrid synchronous control module are additionally arranged in the case of a fault, so that the problem of system out-of-step of a conventional network construction type fan is solved; the transient active control module is arranged, the active power instruction of the converter can be reduced, the adjusted active power instruction is matched with the active power feedback after voltage drop, it is guaranteed that the active power error does not affect the system angular frequency in the fault period as far as possible, and the power angle stability of the system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of renewable energy power generation, and in particular to a hybrid synchronous control system and a control method for a grid-connected wind power converter. Background Art

[0002] In recent years, my country's wind power has developed rapidly. According to statistics from the National Energy Administration, in the first quarter of 2024, my country's new wind power installed capacity was 15.5 million kW. By the end of March 2024, my country's cumulative wind power installed capacity was 460 million kW, a year-on-year increase of 21.5%. With the continuous increase in grid-connected wind power capacity, the interaction between wind turbines and the power grid is becoming stronger and stronger.

[0003] Grid faults will cause a series of problems such as grid voltage drop, increased current in unit converters and generators, increased DC bus voltage, rotor acceleration, etc., which will cause wind turbines to be disconnected from the grid due to protection, expand the scope of grid faults, and bring serious consequences to the stable operation of the grid. Grid voltage phase jumps are difficult to be detected by protection algorithms based on grid voltage RMS measurement, but like sudden drops in grid voltage amplitude, they will cause grid current to increase, the angle difference between the converter and the grid will continue to increase, and synchronization will be lost, causing the converter to be disconnected from the grid due to protection, expanding grid faults. Summary of the invention

[0004] The purpose of the present invention is to provide a method for solving the problem of system desynchronization of a grid-type wind power converter when a grid failure occurs. While improving the stability of the grid-type wind power converter, the damping control coefficient of conventional grid control is omitted, thereby reducing the design difficulty of the grid-type wind power converter.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A hybrid synchronous control system for a grid-type wind power converter, comprising an active power droop control module, a transient active power control module, an active power frequency control module, a hybrid synchronous control module, a system frequency control module, and a phase-locked integral control module;

[0007] The output end of the active power droop control module is connected to the input end of the active power frequency control module to provide the active power control module with the droop active power (P droop );

[0008] The output of the transient active power control module is connected to the input terminal 2 of the active frequency control module to provide the active power control module with the transient active power (P comp );

[0009] The output of the active frequency control module is connected to the input of the system frequency control module to provide the system frequency control module with the frequency change required for power control (Δω P );

[0010] The output of the hybrid synchronous control module is connected to the input terminal 2 of the system frequency control module to provide the system frequency control module with the hybrid synchronous frequency change (Δω) required when the system fails. hsc );

[0011] The output of the system frequency control module is connected to the input end of the phase-locked integral control module to provide the system network control frequency ω for the phase-locked integral control module;

[0012] The output of the phase-locked integral control module is connected to the input end of the hybrid synchronous control module to provide the hybrid synchronous control module with an angle parameter (θ) required for coordinate transformation.

[0013] The input terminals of the active power droop control module are respectively connected to the rated frequency ω of the wind power converter N , wind power converter grid frequency (ω) connection, wind power converter rated frequency (ω N ) is the operating frequency of the wind power converter during normal operation, the wind power converter grid frequency (ω) is the operating frequency of the wind power converter during grid control operation, and the input of the transient active power control module is the grid voltage V g .

[0014] The input quantity of the active frequency control module also includes the active set value (P ref ), active feedback value (P fbk ), active power given value (P ref ) is the power generated by the wind power converter during normal operation, and the active feedback value (P fbk ) is obtained by collecting the voltage and current of the wind power converter.

[0015] The input of the hybrid synchronous control module also includes the voltage of the grid connection point (V pcc ), the voltage at the grid connection point (V pc ) is the voltage at the point where the wind turbine converter is connected to the grid.

[0016] The input of the system frequency control module also includes wind power converters.

[0017] The active power droop control module is a droop controller, which adopts a proportional regulator; the hybrid synchronous control module is a hybrid synchronous controller, which adopts a proportional regulator.

[0018] A hybrid synchronous control method for a grid-connected wind power converter, comprising:

[0019] The rated frequency of the wind power converter ωN The frequency is connected to the droop controller after the difference is made with the wind power converter grid frequency ω, and the output of the droop controller is the droop power;

[0020] The grid voltage (V g ) is greater than (V gN -ε), the transient active power (P comp ) output is 0, when the grid voltage (V g ) is less than or equal to (V gN -ε), the transient active power (P comp ) output is (EU / Z), where (V gN ) is the rated value of the grid voltage, ε is the transient active power control threshold (usually 0.1V gN ), E is the grid voltage, U is the wind power converter port voltage, and Z is the line system impedance;

[0021] The active frequency control module will set the active given value (P ref ), drooping work (P droop ), transient active power (P comp ) and sum the sum and the active feedback value (P fbk ) to make a difference, and send the result of the difference into a time constant (T j ) integral link, the output of the integral link is used as the output of the active frequency control module (Δω P );

[0022] The hybrid synchronous controller obtains the q-axis component of the grid connection point voltage through the abc / dq coordinate transformation module, and inputs the q-axis component of the grid connection point voltage into the hybrid synchronous controller. The output of the hybrid synchronous controller is the hybrid synchronous frequency change (Δω hsc );

[0023] The system frequency control module converts the rated frequency of the wind power converter to N , frequency change Δω P , hybrid synchronous frequency variation (Δω hsc ) are summed up to obtain the output quantity which is the network control frequency (ω);

[0024] The phase-locked integral control module integrates the network control frequency ω to obtain the network operation angle parameter (θ). If the network operation angle parameter (θ) is greater than or equal to 2π, the integral link is reset to zero.

[0025] The transient active power control module outputs according to formula ①, which is as follows:

[0026]

[0027] The abc / dq coordinate transformation module has the following formula:

[0028]

[0029] In formula ②, V pccd 、V pccq is the voltage V at the grid connection point pcc The d-axis component and q-axis component in the rotating dq coordinate system, V pcca 、V pccb 、V pccc is the voltage V at the grid connection point pcc The a-axis component, b-axis component and c-axis component in the stationary abc coordinate system.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. By adding a transient active power control module and a hybrid synchronous control module in case of a fault, the system out-of-step problem of conventional grid-type wind turbines can be solved when a grid-type wind turbine fails;

[0032] 2. A transient active power control module is provided, which can reduce the active power command of the converter when a fault occurs in the power grid. The adjusted active power command matches the active power feedback after the voltage drop, ensuring that the active power error does not affect the system angular frequency during the fault as much as possible, and increasing the power angle stability of the system;

[0033] 3. It is only necessary to set the time constant of power integration, the control coefficient of the droop controller and the control coefficient of the hybrid synchronous controller, eliminating the damping control coefficient of conventional grid control and reducing the design difficulty of the grid-connected wind power converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Block diagram of hybrid synchronous control of grid-connected wind power converter.

[0035] Figure 2 Control block diagram of active power droop control module.

[0036] Figure 3 Active frequency control module control block diagram.

[0037] Figure 4 Control block diagram of hybrid synchronous control module.

[0038] Figure 5 System frequency control module control block diagram.

[0039] Figure 6 Control block diagram of phase-locked integral control module. DETAILED DESCRIPTION

[0040] The present invention is described in detail below in conjunction with the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0041] The following examples are implemented on the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.

[0042] [Example 1]

[0043] A hybrid synchronous control system for grid-connected wind power converters Figure 1 , including active power droop control module, transient active power control module, active power frequency control module, hybrid synchronous control module, system frequency control module and phase-locked integral control module. The output end of the active power droop control module is connected to the input end of the active power frequency control module to provide the active power control module with the droop active power P required for droop control. droop The output of the transient active power control module is connected to the input terminal of the active frequency control module to provide the active power control module with the transient active power P required when the system fails. comp The output of the active frequency control module is connected to the input of the system frequency control module to provide the system frequency control module with the frequency change Δω required for power control P The output of the hybrid synchronous control module is connected to the input terminal of the system frequency control module to provide the system frequency control module with the hybrid synchronous frequency change Δω required when the system fails. hsc ; The output of the system frequency control module is connected to the input of the phase-locked integral control module to provide the system networking control frequency ω for the phase-locked integral control module; the output of the phase-locked integral control module is connected to the input of the hybrid synchronous control module to provide the angle parameter θ required for coordinate transformation for the hybrid synchronous control module.

[0044] The hybrid synchronous control method of grid-type wind power converter is as follows:

[0045] See Figure 2 The input of the active power droop control module includes: wind power converter rated frequency ω N and the grid control frequency ω of the wind power converter, the output of the active droop control module is the droop power P required for droop control droop , the rated frequency of the wind power converter ω N The grid control frequency ω of the wind power converter is connected to the droop controller after the difference is made. The output of the droop controller is the droop power P droop , which is the output of the droop control module; the droop controller is a proportional regulator, and the control coefficient of the droop controller is Kω .

[0046] The input quantity of the transient active power control module is the grid voltage V g , the output is the transient power P comp , the transient active power control module outputs according to formula ①:

[0047]

[0048] In formula ①, when the grid voltage is greater than V gN -ε), P comp The output is 0 when the grid voltage is less than or equal to V gN -ε, P comp The output is EU / Z, where V gN is the rated value of the grid voltage, ε is the transient active power control threshold (usually 0.1V gN ), E is the grid voltage, U is the wind power converter port voltage, and Z is the line system impedance.

[0049] See Figure 3 The input of active frequency control module includes: active given value P ref , Active power feedback value P fbk , Droop active power P droop , transient active power P comp The output of the active frequency control module is the frequency change Δω required for power control P , the active frequency control module will set the active given value P ref , Droop active power P droop , transient active power P comp The sum is calculated and the result is added to the active feedback value P fbk Perform the subtraction and send the result obtained by the subtraction into a time constant T j The output of the integral link is used as the output Δω of the active frequency control module P .

[0050] See Figure 4 The input quantities of the hybrid synchronous control module include: the voltage V at the grid connection point pcc and the angle parameter θ required for coordinate transformation, the output of the hybrid synchronization control module is the hybrid synchronization frequency change Δω hsc First, the grid connection point voltage is transformed through the abc / dq coordinate transformation module to obtain the q-axis component V of the grid connection point voltage pccq , and then the q-axis component of the grid connection point voltage V pccq Input hybrid synchronous controller, the output of hybrid synchronous controller is hybrid synchronous frequency change Δω hsc , the hybrid synchronous controller is a proportional regulator with a control coefficient of Khsc .

[0051] The abc / dq coordinate transformation module is an operation formula as shown below:

[0052]

[0053] In formula ②, V pccd 、V pccq is the voltage V at the grid connection point pcc The d-axis component and q-axis component in the rotating dq coordinate system, V pcca 、V pccb 、V pccc is the voltage V at the grid connection point pcc The a-axis component, b-axis component and c-axis component in the stationary abc coordinate system. . .

[0054] See Figure 5 , the input quantity of the system frequency control module is the system rated frequency ω N , the frequency change Δω required for power control P and the mixed synchronous frequency variation Δω hsc The output of the system frequency control module is the grid control frequency ω, and the rated frequency ω of the wind power converter is N , frequency change Δω P , hybrid synchronous frequency variation Δω hsc The sum is taken and the output quantity is the network control frequency ω.

[0055] See Figure 6 The input of the phase-locked integral control module is the networking control frequency ω, and the output of the phase-locked integral control module is the networking operation angle parameter θ. The networking control frequency is integrated to obtain the networking operation angle parameter θ, and then it is determined whether the networking operation angle parameter θ is greater than or equal to 2π. If the networking operation angle parameter θ is greater than or equal to 2π, the integral link is reset to zero.

[0056] The present invention can solve the problem of system desynchronization of conventional grid-forming wind turbines when a grid fault occurs by adding a transient active power control module and a hybrid synchronous control module in the event of a fault. A transient active power control module is provided, which can reduce the active power instruction of the converter when a grid fault occurs, and the adjusted active power instruction matches the active power feedback after the voltage drop, thereby ensuring that the active power error does not affect the system angular frequency during the fault as much as possible, thereby increasing the power angle stability of the system. Only the time constant of the power integration, the control coefficient of the droop controller and the control coefficient of the hybrid synchronous controller need to be set, thereby eliminating the damping control coefficient of the conventional grid-forming control and reducing the design difficulty of the grid-forming wind power converter.

Claims

1. A hybrid synchronous control system for a grid-connected wind power converter, characterized in that: It includes active power droop control module, transient active power control module, active frequency control module, hybrid synchronization control module, system frequency control module and phase-locked integral control module; The output end of the active power droop control module is connected to the input end of the active power frequency control module to provide the active power control module with the droop active power (P droop ); The output of the transient active power control module is connected to the input terminal 2 of the active frequency control module to provide the active power control module with the transient active power (P comp ); The output of the active frequency control module is connected to the input of the system frequency control module to provide the system frequency control module with the frequency change required for power control (Δω P ); The output of the hybrid synchronous control module is connected to the input terminal 2 of the system frequency control module to provide the system frequency control module with the hybrid synchronous frequency change (Δω) required when the system fails. hsc ); The output of the system frequency control module is connected to the input end of the phase-locked integral control module to provide the system network control frequency ω for the phase-locked integral control module; The output of the phase-locked integral control module is connected to the input end of the hybrid synchronous control module to provide the hybrid synchronous control module with an angle parameter (θ) required for coordinate transformation.

2. A grid-type wind power converter hybrid synchronous control system according to claim 1, characterized in that: The input terminals of the active power droop control module are respectively connected to the rated frequency ω of the wind power converter. N , wind power converter grid frequency (ω) connection, wind power converter rated frequency (ω N ) is the operating frequency of the wind power converter during normal operation, the wind power converter grid frequency (ω) is the operating frequency of the wind power converter during grid control operation, and the input quantity of the transient active power control module is the grid voltage V g .

3. A grid-type wind power converter hybrid synchronous control system according to claim 1, characterized in that: The input quantity of the active frequency control module also includes the active given value (P ref ), active feedback value (P fbk ), active power given value (P ref ) is the power generated by the wind power converter during normal operation, and the active feedback value (P fbk ) is obtained by collecting the voltage and current of the wind power converter.

4. A grid-type wind power converter hybrid synchronous control system according to claim 1, characterized in that: The input quantity of the hybrid synchronous control module also includes the voltage of the grid connection point (V pcc ), the voltage at the grid connection point (V pc ) is the voltage at the point where the wind turbine converter is connected to the grid.

5. A grid-type wind power converter hybrid synchronous control system according to claim 1, characterized in that: The input quantity of the system frequency control module also includes a wind power converter.

6. A grid-type wind power converter hybrid synchronous control system according to claim 2, characterized in that: The active power droop control module is a droop controller, which uses a proportional regulator; the hybrid synchronous control module is a hybrid synchronous controller, which uses a proportional regulator.

7. A method for implementing a hybrid synchronous control of a grid-connected wind power converter according to any one of claims 1 to 6, characterized in that: include: The rated frequency of the wind power converter ω N The frequency is connected to the droop controller after the difference is made with the wind power converter grid frequency ω, and the output of the droop controller is the droop power; The grid voltage (V g ) is greater than (V gN -ε), the transient active power (P comp ) output is 0, when the grid voltage (V g ) is less than or equal to (V gN -ε), the transient active power (P comp ) output is (EU / Z), where (V gN ) is the rated value of the grid voltage, ε is the transient active power control threshold, E is the grid voltage, U is the wind power converter port voltage, and Z is the line system impedance; The active frequency control module sets the active given value (P ref ), drooping work (P droop ), transient active power (P comp ) and sum the sum and the active feedback value (P fbk ) to make a difference, and send the result of the difference into a time constant (T j ) integral link, the output of the integral link is used as the output of the active frequency control module (Δω P ); The hybrid synchronous controller obtains the q-axis component of the grid connection point voltage through the abc / dq coordinate transformation module, and inputs the q-axis component of the grid connection point voltage into the hybrid synchronous controller. The output of the hybrid synchronous controller is the hybrid synchronous frequency change (Δω hsc ); The system frequency control module converts the rated frequency of the wind power converter to N , frequency change Δω P , hybrid synchronous frequency variation (Δω hsc ) are summed up to obtain the output quantity which is the network control frequency (ω); The phase-locked integral control module integrates the network control frequency ω to obtain the network operation angle parameter (θ). If the network operation angle parameter (θ) is greater than or equal to 2π, the integral link is reset to zero.

8. A hybrid synchronous control method for a grid-connected wind power converter according to claim 7, characterized in that: The transient active power control module outputs according to formula ①, which is as follows:

9. A hybrid synchronous control method for a grid-connected wind power converter according to claim 7, characterized in that: The abc / dq coordinate transformation module has the following formula: In formula ②, V pccd 、V pccq is the voltage V at the grid connection point pcc The d-axis component and q-axis component in the rotating dq coordinate system, V pcca 、V pccb 、V pccc is the voltage V at the grid connection point pcc The a-axis component, b-axis component and c-axis component in the stationary abc coordinate system.

Images