A network configuration type wind turbine control method based on transient damping compensation

Abstract

The application belongs to the technical field of wind power generation, and particularly discloses a network-constructed wind turbine control method based on transient damping compensation. The method introduces an improved VSG control strategy of transient power compensation, constructs transient power through state damping and a first-order lag link, and dynamically supports virtual damping adjustment capacity through an extended state algorithm. The improved second-order motion equation of the VSG system can damp active oscillation of the system, improve the regulation time of the dynamic process, reduce the impact power, and effectively improve the stability of the VSG system of the wind turbine.

Description

Technical Field

[0001] This invention belongs to the field of wind power generation technology and is used to optimize the stability of wind power grid-connected systems. Specifically, it is a grid-connected wind turbine control method based on transient damping compensation. Background Technology

[0002] To ensure the stability of new energy power systems, grid-connected wind power based on virtual synchronous control has become an important support for high-efficiency and high-voltage power systems. The virtual synchronous generator (VSG) control strategy, which does not require PLL (phase locked loop) dominance, can provide dynamic stability support for the power grid by introducing the mechanical motion equation of the synchronous machine rotor and the excitation voltage droop control into the wind turbine converter.

[0003] like Figure 1 The diagram shows the principle block diagram of a direct-drive wind turbine control structure based on VSG. Virtual synchronous generation control is essentially a voltage source control method, but unlike traditional voltage-source droop control methods, it adds a VSG control strategy to the grid-side inverter of the direct-drive wind turbine. The VSG introduces virtual rotational inertia and virtual damping coefficients to simulate the rotor motion equations of a synchronous machine, constructing an active power loop that effectively improves grid inertia and damping. (See diagram.) For direct-drive fans to follow the MPPT curve, , These are the filter inductor and the filter capacitor, respectively. This is the voltage at the wind turbine's grid connection point.

[0004] like Figure 2 The diagram shown is a block diagram of the active power loop control structure of a virtual synchronous direct-drive wind turbine (VSG). The rotor motion equations simulate the inertia and primary frequency regulation characteristics of the synchronous machine, where... , The inertia and damping control parameters are given by the rotor motion equation, and the virtual phase angle is obtained through the rotor motion equation and voltage droop control. and voltage amplitude Finally, by controlling virtual impedance and voltage / current, the modulation signal of the grid-side PWM converter is obtained, thus achieving active support for the system's inertia and damping. The angular frequency of the grid connection point voltage. It outputs active power to the direct-drive fan.

[0005] However, for the traditional VSG damping coefficient, when the virtual damping coefficient... Reducing the amount of material will negatively impact the dynamic stability of the fan's shaft system.

[0006] Therefore, in order to safely promote wind power control technology based on virtual synchronous machines, it is necessary to give a new VSG control strategy to improve the dynamic stability performance of wind power VSG grid-connected systems. Summary of the Invention

[0007] The purpose of this invention is to provide a grid-connected wind turbine control method based on transient damping compensation. Under the control mode set by this method, the virtual damping coefficient is effectively increased to improve the dynamic stability performance of the wind power VSG grid-connected system.

[0008] To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0009] A control method for grid-type wind turbines based on transient damping compensation improves the system's stability characteristics and anti-interference capability through an improved VSG, specifically including the following processes:

[0010] An improved VSG control strategy with transient power compensation is introduced. Transient power is constructed through state damping and first-order hysteresis, and virtual damping adjustment capability is dynamically supported by an extended state algorithm.

[0011] The improved second-order equation of motion for the VSG system is as follows:

[0012]

[0013] in, The moment of inertia represents the equation of motion of the rotor. The damping control parameters represent the rotor's motion equations. This indicates an improvement in the virtual phase angle of the VSG. To improve the feedback error gain coefficient of the VSG's output virtual angular velocity, Represents the extended state function. This represents the control coefficients of the improved VSG rotor motion equation.

[0014] As a constraint, the motion equations of the VSG virtual rotor, incorporating transient power and extended state algorithms, are as follows:

[0015]

[0016] in, This indicates the output virtual angular velocity after the VSG was improved. express The output gain is adjusted. Indicates the initial angular velocity of the wind turbine. This indicates an improvement in the active power input of the VSG. This indicates an improvement in the transient power compensation of the VSG. This indicates an improvement in the damping power of the VSG;

[0017] The extended state function is expressed as

[0018]

[0019] in, This represents the nonlinear state factor, with a value range of [0,1]. This represents the filter factor, with a value range of [5, 100].

[0020] As a further limitation, the active power input of the VSG is improved. Represented as

[0021]

[0022] in, This indicates that the wind turbine captures wind energy through its blades and converts it into mechanical energy; This indicates an improvement in the feedback power of the primary frequency modulation stage of the VSG, specifically expressed as follows:

[0023]

[0024] in, This indicates an improvement in VSG error power. Indicates the error gain coefficient. First-order lag time constant, Indicates the frequency modulation coefficient. Represents the Laplace operator;

[0025] This indicates an improvement in VSG output power, expressed as:

[0026]

[0027] in, This represents the improved VSG voltage amplitude obtained from the virtual excitation circuit. This indicates the voltage at the wind turbine's grid connection point. Indicates the line reactance;

[0028] Represented as

[0029]

[0030] in, Indicates the angular frequency of the feedback error. express The feedback error gain coefficient.

[0031] As a further limitation, improve the transient power compensation of VSG. Represented as

[0032]

[0033] in, This indicates an improvement in the state damping of the VSG. This represents the time constant of the first-order lag element in the improved VSG.

[0034] As a further refinement, the process of obtaining the improved second-order equations of motion for the VSG system is carried out in the following order:

[0035] S1, when the initial angular velocity of the fan is At the equilibrium point, the equation is... Linearizing the rotor motion equations, we obtain the small perturbation equations.

[0036] ;

[0037] S2, Combined And the wind turbine captures wind energy through its blades and converts it into mechanical energy. The input power perturbation of the improved VSG is obtained.

[0038] ;

[0039] in, This indicates the initial virtual phase angle value for the improved VSG;

[0040] S3. Obtain the improved transient power compensation of VSG. Disturbance

[0041] ;

[0042] S4. Obtain the damping power of the improved VSG. Disturbance

[0043]

[0044] S5, Joint type Japanese style have to

[0045] ;

[0046] S6, Further Resolution The improved second-order equations of motion for the VSG system are obtained.

[0047] The present invention, by adopting the above-described technical solution, achieves the following technical advancements compared to existing technologies:

[0048] (1) This invention introduces a transient power compensation VSG control strategy, constructs transient power through state damping and first-order lag, and dynamically supports virtual damping adjustment capability through extended state algorithm. This strategy can dampen the active oscillation of the system, improve the adjustment time of the dynamic process, and reduce the impact power, effectively improving the stability of the wind turbine VSG system.

[0049] (2) Improve VSG by introducing state damping Angular velocity tracking function Afterwards, the system's eigenvalues ​​shift to the left, enhancing the system's stability. , The increase of VSG will make the transient frequency fluctuation of the system more stable and reduce the overshoot of the frequency after disturbance. That is, the improved VSG can improve the stability characteristics and anti-interference ability of the system.

[0050] (3) The present invention can further improve the damping capacity of wind turbines and quickly suppress the oscillation of active power in the system, thereby effectively improving the dynamic stability of wind power VSG grid connection system.

[0051] This invention belongs to the field of wind power generation technology and can improve the stability of grid-connected wind power systems. Attached Figure Description

[0052] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0053] In the attached diagram:

[0054] Figure 1 This is a block diagram illustrating the principle of the VSG-based direct-drive fan control structure in the prior art of this invention.

[0055] Figure 2 This is a block diagram of the active circuit control structure of the VSG for a virtual synchronous direct-drive wind turbine, which is a prior art technology of this invention.

[0056] Figure 3 This is a block diagram illustrating the principle of the improved virtual synchronous direct-drive wind turbine active power control structure according to an embodiment of the present invention.

[0057] Figure 4 This is a schematic diagram of the simulation system model of a wind power grid-connected system based on VSG, according to an embodiment of the present invention.

[0058] Figure 5 This is a comparison chart of the system angular frequency change curves under a sudden load increase in an embodiment of the present invention;

[0059] Figure 6 This is a comparison chart of the fan angular velocity change curves under simulated sudden load increases in an embodiment of the present invention;

[0060] Figure 7 This is a comparison chart of wind power output response under simulated load surge in an embodiment of the present invention;

[0061] Figure 8 This is a comparison chart of simulated tie-line transmission power in an embodiment of the present invention;

[0062] Figure 9 Simulated synchronous generator for an embodiment of the present invention , Comparison diagram of equivalent work angles. Detailed Implementation

[0063] The preferred embodiments of the present invention will now be described with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0064] Example: A control method for grid-type wind turbines based on transient damping compensation

[0065] This embodiment is mainly divided into three parts. The first part analyzes the stability characteristics of the virtual synchronous PMSG integrated into the synchronous machine system in the prior art and finds the factors affecting the dynamic stability of the wind turbine. The second part gives the VSG control structure based on state power compensation. The third part builds a simulation system model based on Simulink to verify the control method provided in this embodiment.

[0066] I. Stability Analysis of Direct-Drive Wind Power Grid-Connected System Based on VSG Control

[0067] Figure 2 In this context, the motion equations of the VSG virtual rotor can be expressed as:

[0068]

[0069] in, , These are the virtual phase angle and virtual angular velocity of the VSG, respectively. This is the reference input power for the VSG active power control loop;

[0070]

[0071] Direct-drive wind turbines include wind turbines, frequency converters, and generators. Wind turbines capture wind energy through their blades and convert it into mechanical energy. ;

[0072]

[0073] In the formula: R is the air density; R is the radius of the wind turbine blades; The angular velocity of the fan; The tip speed ratio; Indicates the wind energy conversion coefficient; The wind energy utilization coefficient function is and It is a bivariate function, where β is the propeller pitch angle.

[0074] Furthermore, the feedback power of the VSG primary frequency modulation stage is expressed as: , Frequency modulation coefficient

[0075]

[0076] Through virtual damping element Obtain the damping power

[0077]

[0078] Indicates the angular frequency of the feedback error;

[0079] After adopting VSG control, the direct-drive fan outputs active power of:

[0080]

[0081] in, The voltage amplitude of VSG obtained from the virtual excitation circuit. This is the voltage at the wind turbine's grid connection point.

[0082] When the initial angular velocity of the fan is At the equilibrium point, the equation is... Linearizing the rotor motion equations, we obtain the small perturbation equations as follows:

[0083]

[0084] Ignoring the rate of change of the wind turbine rotor angular velocity, the change in the reference input power of the VSG active power control loop

[0085]

[0086] Joint ,Mode have to

[0087]

[0088] Further resolution yields the second-order equations of motion for the system.

[0089]

[0090] From the formula It is known that in existing technologies, the VSG damping coefficient is directly related to the real part, and when the virtual damping coefficient... When the number of roots decreases, the system's characteristic roots move closer to the imaginary axis of the state plane, which is detrimental to the dynamic stability of the fan's shaft system.

[0091] II. VSG Control Structure Based on State Power Compensation

[0092] like Figure 3 The diagram shown is a block diagram illustrating the principle of the improved virtual synchronous direct-drive wind turbine active power control structure in this embodiment. Based on Figure 3 Given the structure, the motion equations of the VSG virtual rotor, incorporating transient power and extended state algorithms, can be expressed as:

[0093]

[0094] in, This indicates the output virtual angular velocity after the VSG was improved. express The output gain is adjusted. Indicates the initial angular velocity of the wind turbine. This indicates an improvement in the active power input of the VSG. This indicates an improvement in the transient power compensation of the VSG. This indicates an improvement in the damping power of the VSG. The moment of inertia represents the equation of motion of the rotor. This represents the extended state function.

[0095] Extended state function It can achieve the following: For accurate tracking, the expression is:

[0096]

[0097] in, This represents the nonlinear state factor, with a value range of [0,1]. This represents the filter factor, with a value range of [5, 100].

[0098] Improve the active power input of VSG to

[0099]

[0100] in, This indicates that the wind turbine captures wind energy through its blades and converts it into mechanical energy; This indicates an improvement in the feedback power of the primary frequency modulation stage of the VSG, specifically expressed as follows:

[0101]

[0102] in, This indicates an improvement in VSG error power. Indicates the error gain coefficient. First-order lag time constant, Indicates the frequency modulation coefficient. Represents the Laplace operator;

[0103] This indicates an improvement in VSG output power, expressed as:

[0104]

[0105] in, This represents the improved VSG voltage amplitude obtained from the virtual excitation circuit. This indicates the voltage at the wind turbine's grid connection point. Indicates the line reactance;

[0106] Improve the damping power of the VSG Represented as

[0107]

[0108] in, Indicates the angular frequency of the feedback error. express The feedback error gain coefficient.

[0109] Furthermore, improve the transient power compensation of VSG. Represented as

[0110]

[0111] in, This indicates an improvement in the state damping of the VSG. This represents the time constant of the first-order lag element in the improved VSG.

[0112] When the initial angular velocity of the fan is At the equilibrium point, the equation is... Linearizing the rotor motion equations, we obtain the small perturbation equations as follows:

[0113]

[0114] Joint The input power disturbance of the improved VSG is obtained as follows:

[0115] ;

[0116] in, This indicates the initial value of the virtual phase angle for improving the VSG.

[0117] Furthermore, it can be seen that the transient power compensation of the VSG can be improved. Disturbance

[0118]

[0119] Improve the damping power of the VSG Disturbance

[0120]

[0121] Joint Japanese style have to

[0122] ;

[0123] This represents the control coefficient of the improved VSG rotor motion equation, and is an intermediate quantity;

[0124] Further solutions yielded the improved second-order equations of motion for the VSG system.

[0125]

[0126] With formula In comparison, the improved VSG introduces state damping. Angular velocity tracking function Afterwards, the system's eigenvalues ​​shift to the left, enhancing the system's stability; with... , The increase of VSG will make the transient frequency fluctuation of the system more stable and reduce the overshoot of the frequency after disturbance to a certain extent. Therefore, the improved VSG can improve the stability characteristics and anti-interference ability of the system.

[0127] III. Simulation Verification

[0128] Built with Simulink Figure 4The simulation system model shown includes: three synchronous generators G1 to G3, each with a rated capacity of 800MW; a wind farm consisting of 90 permanent magnet synchronous generators (PMSGs) connected in parallel, each PMSG having a rated capacity of 2MW; four transformers T1 to T4 with identical parameters; and busbars B1 to B2. 10 Loads L1 and L2.

[0129] The wind farm is connected to the system via bus B2, with load L1 at 362MW and load L2 at 197MW. Each permanent magnet synchronous generator (PMSG) is equipped with a wind turbine and converter circuit.

[0130] Verification of the effectiveness of the improved wind turbine VSG control strategy: The rated wind speed of the permanent magnet synchronous generator (PMSG) is 8 m / s. At the 10th second, the load L1 suddenly increases by 130 MW. The system angular frequency, wind power output, and wind turbine angular velocity response waveforms are obtained as follows: Figures 5-7 As shown. From Figure 5 It can be seen that the lowest oscillation angular frequency increased from 0.9935 in traditional control to 0.9965, and the oscillation time was shortened to 6.5s for stabilization; from Figure 6 It can be seen that the minimum angular velocity has increased from 0.993 in traditional control to 0.996; from Figure 7 As can be seen, the improved control reduces the oscillation time to 7 seconds, while the traditional control requires 9.5 seconds to stabilize. This demonstrates that by adopting the improved wind turbine VSG control strategy, the system frequency oscillation amplitude is reduced, and the wind turbine speed is smoothly restored, thereby reducing the impact of load switching on the system and wind turbine units. Therefore, the improved control strategy in this embodiment can effectively improve the stability of the wind power grid-connected system.

[0131] Figure 8 , Figure 9 Power transmission for tie lines and synchronous generators and Comparison curves of dynamic response at equivalent work angles. From Figure 8 , Figure 9 As can be seen, after the fault occurs, the first swing amplitude of the power angle of the wind power under the traditional virtual synchronization mechanism is large, and the system experiences power oscillation, which reduces the transient stability capability of the system. The traditional control requires 9.7s to stabilize. After adopting the improved VSG control strategy, the first swing amplitude of the system power angle is reduced, and the active power of the tie line and the generator can recover to stability more quickly. The oscillation time is shortened to 5.2s. Therefore, the improved VSG control strategy can significantly improve the stable operation capability of the system.

Claims

1. A control method for grid-type wind turbines based on transient damping compensation, characterized in that, The improved VSG enhances the system's stability and anti-interference capabilities, specifically through the following processes: An improved VSG control strategy with transient power compensation is introduced. Transient power is constructed through state damping and first-order hysteresis, and virtual damping adjustment capability is dynamically supported by an extended state algorithm. The improved second-order equation of motion for the VSG system is as follows: in, The moment of inertia represents the equation of motion of the rotor. The damping control parameters represent the rotor's motion equations. This indicates an improvement in the virtual phase angle of the VSG. To improve the feedback error gain coefficient of the VSG's output virtual angular velocity, Represents the extended state function. This represents the control coefficients of the improved VSG rotor motion equation.

2. The method for controlling a grid-type wind turbine based on transient damping compensation according to claim 1, characterized in that, The motion equations of the VSG virtual rotor, incorporating transient power and extended state algorithms, are as follows: in, This indicates the output virtual angular velocity after the VSG was improved. express The output gain is adjusted. Indicates the initial angular velocity of the wind turbine. This indicates an improvement in the active power input of the VSG. This indicates an improvement in the transient power compensation of the VSG. This indicates an improvement in the damping power of the VSG; The extended state function is expressed as in, This represents the nonlinear state factor, with a value range of [0,1]. This represents the filter factor, with a value range of [5, 100].

3. The method for controlling a grid-type wind turbine based on transient damping compensation according to claim 2, characterized in that, Improve the active power input of VSG Represented as in, This indicates that the wind turbine captures wind energy through its blades and converts it into mechanical energy; This indicates an improvement in the feedback power of the primary frequency modulation stage of the VSG, specifically expressed as follows: in, This indicates an improvement in VSG error power. Indicates the error gain coefficient. First-order lag time constant, Indicates the frequency modulation coefficient. Represents the Laplace operator; This indicates an improvement in VSG output power, expressed as: in, This represents the improved VSG voltage amplitude obtained from the virtual excitation circuit. This indicates the voltage at the wind turbine's grid connection point. Indicates the line reactance; Represented as in, Indicates the angular frequency of the feedback error. express The feedback error gain coefficient.

4. The grid-type wind turbine control method based on transient damping compensation according to claim 3, characterized in that, Improved transient power compensation for VSG Represented as in, This indicates an improvement in the state damping of the VSG. This represents the time constant of the first-order lag element in the improved VSG.

5. The grid-type wind turbine control method based on transient damping compensation according to claim 4, characterized in that, The process of obtaining the improved second-order equations of motion for the VSG system is carried out in the following steps: S1, when the initial angular velocity of the fan is Linearizing the rotor motion equation of equation 11 at the equilibrium point yields the small perturbation equation. ; S2, combined type 13, and wind turbines capture wind energy through blades and convert it into mechanical energy. The input power perturbation of the improved VSG is obtained. ； in, This indicates the initial virtual phase angle value for the improved VSG; S3. Obtain the transient power compensation of the improved VSG. Disturbance ; S4. Obtain the damping power of the improved VSG. Disturbance S5, Combined Form (18) and Form have to ； S6, Further Resolution The improved second-order equations of motion for the VSG system are obtained.

Images