Active-disturbance-rejection control method for suppressing subsynchronous oscillation of doubly-fed wind turbine generator

Abstract

The invention discloses an active disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator, which relates to the technical field of power system control and comprises the following steps: estimating subsynchronous current disturbance of a first controlled object in real time through a first extended state observer; using a first nonlinear state error feedback control strategy to perform feedback control according to the disturbance estimated by the extended state observer; the rotor current is kept constant, and subsynchronous oscillation is suppressed. According to the method, the sub-synchronous current disturbance of the controlled object is estimated in real time through the extended state observer, accurate estimation of the sub-synchronous current disturbance on the rotor side of the doubly-fed wind turbine generator is achieved, effective feedback control can be conducted on the estimated disturbance by adopting a nonlinear state error feedback control strategy, and therefore the disturbance disturbance can be effectively controlled. The feedback control output variable is calculated through the optimal control function and the current feedback error, real-time compensation of disturbance is achieved, the dynamic response speed of the system is increased, and the disturbance suppression capacity of the system is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of power system control, and in particular to an auto-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator set. Background Art

[0002] With the rapid development of renewable energy generation such as wind power and photovoltaics, large-scale clusters of power electronic converters are connected to the power grid, causing new oscillation problems such as subsynchronous oscillations, which seriously threaten the safe operation of the power grid and equipment.

[0003] The main problems of existing subsynchronous oscillation suppression technology are as follows: the generation mechanism of subsynchronous oscillation involves the dynamic interaction between multiple converters, renewable energy units and AC / DC power grids. The oscillation frequency, damping or stability is affected by many parameters of the converter and power grid, and even external conditions such as wind and light. It has the characteristics of complex influencing factors and large-scale time-varying, and it is difficult to establish an accurate mathematical model; the oscillation frequency of subsynchronous oscillation presents random time-varying and wide-range characteristics, which is difficult to effectively suppress through fixed control strategies; the converter has complex nonlinear characteristics and limited overload capacity, and the control signal is easily limited, so that the oscillation often starts with small signal negative damping divergence and ends with Nonlinear continuous oscillations bring new difficulties to the detection and suppression of subsynchronous oscillations; modeling is difficult and the control effect is poor. In actual engineering, especially in the modeling process, it is often accompanied by unknown interference, parameter uncertainty and model inaccuracy, which causes the state of the model to often deviate from the normal state and makes it difficult to achieve precise control; operating conditions change frequently and are difficult to adapt to. Due to the randomness of wind energy, the operating conditions of doubly fed wind turbines often change, making it difficult to suppress subsynchronous oscillations under constant parameters; lack of versatility and limited scope of application. Currently, there are few mitigation measures applicable to a variety of operating conditions, which make it difficult to adapt to subsynchronous oscillation problems in different scenarios. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: the existing subsynchronous oscillation suppression method has poor adaptability, poor control effect, large nonlinear characteristics of the converter and control difficulty, and how to estimate and compensate the subsynchronous current disturbance in the rotor of the doubly fed wind turbine in real time, and use the nonlinear state error feedback control strategy to perform feedback control according to the disturbance estimated by the extended state observer to keep the rotor current constant, thereby effectively suppressing the subsynchronous oscillation.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: an anti-disturbance control method for suppressing subsynchronous oscillations of a doubly-fed wind turbine generator set, comprising estimating the subsynchronous current disturbance of a first controlled object in real time through a first extended state observer; using a first nonlinear state error feedback control strategy to perform feedback control according to the disturbance estimated by the extended state observer; keeping the rotor current constant to suppress subsynchronous oscillations.

[0007] As a preferred scheme of the self-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine set described in the present invention, wherein: the first extended state observer includes determining the state information and subsynchronous current disturbance of the system through the optimal control function according to the input and output of the first controlled object.

[0008] As a preferred solution of the auto-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system described in the present invention, the input of the first controlled object includes the rotor-side converter voltage and the rotor-side converter current.

[0009] As a preferred solution of the auto-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine set described in the present invention, wherein: the first nonlinear state error feedback control strategy includes feedback control of output variables through optimal control function and current feedback error calculation.

[0010] As a preferred scheme of the self-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine set described in the present invention, wherein: the feedback control based on the disturbance estimated by the extended state observer includes calculating the current feedback error through the current reference value and the current state estimated in the extended state observer.

[0011] As a preferred solution of the self-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine set described in the present invention, wherein: the keeping the rotor current constant includes performing feedback control according to the feedback control output variable and the compensation process, and calculating the final control variable.

[0012] As a preferred solution of the auto-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system described in the present invention, the subsynchronous oscillation suppression includes a final control variable for controlling the voltage and current of the rotor-side converter.

[0013] Another object of the present invention is to provide an anti-disturbance control system for suppressing subsynchronous oscillations of a doubly-fed wind turbine generator set, which can perform feedback control based on disturbances estimated by an extended state observer, calculate feedback control output variables through an optimal control function and a current feedback error, and calculate a current feedback error based on a current reference value and a current state estimated in the extended state observer, thereby solving the problem that current subsynchronous oscillation suppression methods contain nonlinear characteristics of the converter and are difficult to control.

[0014] As a preferred solution of the self-disturbance rejection control system for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator set described in the present invention, it includes: an extended state observer module, a feedback control strategy module, and a rotor current constant control module; the extended state observer module is used to estimate the subsynchronous current disturbance of the first controlled object in real time, and determine the state information and subsynchronous current disturbance of the system through the optimal control function according to the input and output of the first controlled object; the feedback control strategy module is used to perform feedback control according to the disturbance estimated by the extended state observer, calculate the feedback control output variable through the optimal control function and the current feedback error, and calculate the current feedback error according to the current reference value and the current state estimated in the extended state observer; the rotor current constant control module is used to keep the rotor current constant and suppress subsynchronous oscillation.

[0015] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of an auto-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine set.

[0016] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of an auto-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator set.

[0017] Beneficial effects of the present invention: The self-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine provided by the present invention estimates the subsynchronous current disturbance of the first controlled object in real time through a first extended state observer, thereby realizing accurate estimation of the subsynchronous current disturbance on the rotor side of the doubly-fed wind turbine. The state information and disturbance of the system are determined through an optimal control function, so that the system can quickly identify and respond to the occurrence of subsynchronous oscillations, thereby improving the detection sensitivity of the system to subsynchronous oscillations, and providing accurate basic data for subsequent control strategies. By taking the rotor-side converter voltage and current as input, the actual operating conditions of the motor during operation can be considered more comprehensively, thereby improving the adaptability and robustness of the control strategy, and achieving The purpose of preventing subsynchronous oscillations in advance and responding to them in time is achieved, and the safe and stable operation of wind turbines is ensured. By adopting a nonlinear state error feedback control strategy, effective feedback control can be performed according to the disturbance estimated by the extended state observer. The feedback control output variable is calculated by the optimal control function and the current feedback error, and real-time compensation for the disturbance is achieved. Not only the dynamic response speed of the system is improved, but also the system's ability to suppress disturbances is enhanced. Feedback control is performed according to the feedback control output variable and the compensation process, and the final control variable is calculated to keep the rotor current constant, so that subsynchronous oscillations can be effectively suppressed. The present invention achieves better results in terms of adaptability, robustness and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0019] Figure 1 An overall flow chart of an auto-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator set provided in the first embodiment of the present invention.

[0020] Figure 2 A comparison diagram of a rotor-side PI control strategy and an active disturbance rejection control strategy for an active disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine set provided in the first embodiment of the present invention.

[0021] Figure 3 An experimental system model diagram of an auto-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator set provided in the second embodiment of the present invention.

[0022] Figure 4 A PI controller and dynamic response diagram of an auto-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine provided in the second embodiment of the present invention include (a) 500kV line active power, (b) 500kV line reactive power, (c) rotor current q-axis component, (d) rotor current d-axis component and (e) line A phase current.

[0023] Figure 5 The line current spectrum diagram of an active disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine provided in the second embodiment of the present invention includes (a) a PI control strategy line current spectrum and (b) an active disturbance rejection control line current spectrum.

[0024] Figure 6 A schematic diagram of a module of an active disturbance rejection control system for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator system provided in a third embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0026] Example 1, reference Figure 1 and Figure 2, which is an embodiment of the present invention, provides an auto-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator set, comprising:

[0027] S1: Estimate the subsynchronous current disturbance of the first controlled object in real time through a first extended state observer.

[0028] Furthermore, the first extended state observer includes determining the state information and the subsynchronous current disturbance of the system through an optimal control function according to the input and output of the first controlled object.

[0029] The first extended state observer (ESO) includes but is not limited to a standard extended state observer, an adaptive extended state observer, a nonlinear extended state observer, a time-delay compensation extended state observer, etc.; the first controlled object is a mathematical model of the rotor side of the doubly fed wind turbine generator set, including a rotor side converter, a rotor winding, a stator winding, a stator-rotor mutual inductance, etc.

[0030] The first controlled object includes but is not limited to incorporating other components of the wind turbine, such as the wind rotor, tower, etc., into the controlled object model, for example, considering the influence of factors such as the rotation speed and pitch angle of the wind rotor on the rotor current. The model of the power grid can be incorporated into the controlled object model, for example, considering the influence of factors such as the voltage, frequency, and impedance of the power grid on the rotor current. A more accurate mathematical model can be selected according to actual conditions, for example, using a vector control model, a direct torque control model, etc., for example, considering the influence of factors such as the switching frequency and dead time of the converter on the rotor current.

[0031] It should be noted that the first extended state observer may have a variety of structural options and parameter settings, such as a standard extended state observer or an adaptive extended state observer.

[0032] When the system parameters are known or measurable, a standard ESO structure is used, and the ESO parameters are directly set according to the system parameters, for example, the gain coefficient is set according to the sampling step size and the system parameters, and the compensation factor is directly determined according to the system parameters.

[0033] When system parameters are unknown or difficult to measure, an adaptive ESO structure is used, and the ESO parameters are automatically adjusted according to the system operation data. For example, adaptive algorithms such as recursive least squares or gradient descent are used to optimize the parameters to minimize the ESO estimation error.

[0034] When the system operating conditions change frequently, an adaptive ESO structure is used to automatically adjust the ESO parameters according to the changes in the system operating conditions. For example, the ESO parameters are dynamically adjusted according to changes in operating parameters such as wind speed, power, and grid frequency to adapt to different operating conditions.

[0035] When there are nonlinear factors in the system, a nonlinear ESO structure is used. For example, feedback linearization technology is used to transform the nonlinear system into a linear system, or nonlinear models such as neural networks are used for state estimation.

[0036] When there is time delay in the system, time delay compensation technology is used, for example, Smith predictor or internal model control is used to eliminate the influence of time delay on ESO estimation.

[0037] As a preference, in this embodiment, the first extended state observer adopts a standard extended state observer, and its principle steps are as follows:

[0038] The system model is constructed using the input (rotor-side converter voltage and current) and output (state quantity) information of the system. The system state is estimated through the observer, the subsynchronous current disturbance information is extracted, and the estimated disturbance information is fed back to the controller to achieve dynamic compensation.

[0039] Furthermore, the input of the first controlled object includes the rotor-side converter voltage u rx and the rotor-side converter current i rx , rotor side converter voltage u rx Including the rotor converter d-axis voltage u rd and the rotor converter q-axis voltage u rq , rotor-side converter current i rx Including the rotor converter d-axis current i rd and the rotor converter q-axis current i rq , the output of the first controlled object includes the state quantity z 1x and state quantity z 2c .

[0040] Furthermore, when the doubly fed wind turbine experiences subsynchronous oscillation, the mathematical equation on the rotor side is expressed as:

[0041]

[0042] Among them, r is the rotor, s is the stator, and u rd 、u rq are the d-axis and q-axis voltages output by the rotor-side converter, R r is the rotor winding resistance, i rd 、i rq are the d-axis and q-axis currents output by the rotor-side converter, ω slip is the generator slip, ψ s is the stator flux, L s is the stator self-inductance, L r is the rotor self-inductance, L m is the stator-rotor mutual inductance, σ is the magnetic leakage coefficient, σ=1-L m 2 / (L r L s ), f1(Δi sub_rd ,Δi sub_rq )、f2(Δi sub_rd ,Δi sub_rq ) is the rotor current disturbance caused by subsynchronous oscillation.

[0043] In order to achieve the decoupling of the d-axis and q-axis, the cross-coupling term is also considered as a disturbance component, and the mathematical equation on the rotor side is rewritten as follows:

[0044]

[0045] Among them, F1(Δi sub_rd ,Δi sub_rq )、F2(Δi sub_rd ,Δi sub_rq ) is the total disturbance, and b is the compensation factor.

[0046] By rewriting the rotor side mathematical equation, an anti-disturbance control strategy is established to replace the rotor side PI controller, such as Figure 2 As shown, according to the input and output of the first controlled object, the state information and disturbance of the system are determined to accurately track the reference value and finally achieve the expected goal. rx The real-time tracking and estimation of system disturbances are used to design the standard ESO structure, which can be expressed as:

[0047] e ex =z 1x -i rx

[0048] fe=fal(e ex ,α 1x ,δ 1x )

[0049] fe1=fal(e ex ,α 2x ,δ 2x )

[0050] z 1x =z 1x +h(z 2x -β 01x fr+b x u x )

[0051] z 2x =z 2x +h(-β 02x fe1)

[0052] Where x is the d-axis or q-axis, i rx is the rotor-side converter current, eex is the error term in the extended state observer, subscript e is the extended state observer, z 1x 、z 2x is the current state quantity estimated in the extended state observer, fe and fe1 are the error terms after being processed by the optimal control function fal, fal is the optimal control function, α 1x , α 2x is a constant between 0 and 1, α 1x , α 2x The nonlinear characteristics used to adjust the function are set to 0.5, h is the sampling step size, and δ 1x , δ 2x is the filter factor in the optimal control function, δ 1x , δ 2x can be set equal to the sampling step h, β 01x , β 02x is the gain coefficient, β 01x , β 02x Used to adjust the accuracy of state estimation, which depends on the sampling step size. Regardless of the object, as long as the sampling step size is the same, the same β value or a smaller β value can be used. x is the converter voltage, b x is the compensation factor.

[0053] The optimal control parameters are expressed as:

[0054]

[0055] In another feasible embodiment, the first extended state observer adopts an adaptive extended state observer, and its principle steps are as follows:

[0056] First, the system state model is constructed by combining the real-time collected input signals, including the voltage and current of the rotor-side converter, with the output signals, such as the rotor current and the stator current. Using the adaptive algorithm, the observer parameters are dynamically adjusted during the system operation to cope with nonlinear characteristics and external disturbances. For example, when the system detects abnormal fluctuations in the rotor current, the observer will calculate the error and update the observer gain based on the current measured current value and the reference current value to enhance the response speed to the disturbance. The real-time estimated state information includes subsynchronous disturbances and disturbances related to grid frequency changes. These disturbances are compensated by the set feedback mechanism to achieve precise control of the rotor current. For example, when the load suddenly increases, the adaptive extended state observer can quickly identify the current that exceeds the set range, and quickly reduce the current fluctuation amplitude by adjusting the control input, such as increasing the output voltage of the converter, to ensure system stability and improve the response speed. Through such dynamic adjustment, the subsynchronous oscillation phenomenon can be effectively suppressed to ensure the safe and efficient operation of the doubly fed wind turbine.

[0057] S2: Using the first nonlinear state error feedback control strategy, feedback control is performed according to the disturbance estimated by the extended state observer.

[0058] Furthermore, the first nonlinear state error feedback control strategy includes the following steps: Nx Calculate the feedback control output variable u 0x .

[0059] The first nonlinear state error feedback (NLSEF) control strategy includes but is not limited to proportional differential (PD) control, proportional integral differential (PID) control, adaptive control, fuzzy control, etc.

[0060] NLSEF structure selection and parameter setting include but are not limited to:

[0061] When the system has a high requirement for response speed, the proportional differential (PD) control structure is adopted, and the proportional coefficient k is appropriately increased to improve the system response speed.

[0062] When the system has high requirements for noise suppression capability, a proportional-integral-derivative (PID) control structure is adopted, and the proportional coefficient k, integral coefficient ki and differential coefficient kd are appropriately adjusted to balance the system response speed and noise suppression capability.

[0063] It should be noted that the first nonlinear state error feedback control strategy can be implemented in a variety of ways, such as proportional differential control or proportional integral differential control.

[0064] As a preference, in this embodiment, the first nonlinear state error feedback control strategy is proportional differential control, and its principle steps are as follows:

[0065] The current state obtained by the first extended state observer is compared with the reference current value to calculate the current feedback error, and the current feedback error is used to generate a control output through a PD control formula to adjust the output voltage of the rotor-side converter.

[0066] Furthermore, feedback control based on the disturbance estimated by the extended state observer includes the following steps: rxref and the estimated current state z in the extended state observer Nx Calculate the current feedback error e Nx .

[0067] Furthermore, the first nonlinear state error feedback control strategy can effectively reduce disturbances and enhance the stability of the system through reasonable feedback rules. The active disturbance rejection controller is a first-order controller that uses the proportional differential PD control method of the adaptive filter, which is expressed as:

[0068]

[0069] Where N = 1, 2, z Nx For z 1x 、z 2x , α Nx is α 1x , α 2x , δ Nx is δ 1x , δ 2x , k is the proportional coefficient for adjusting the response speed. The larger the k value is, the faster the system tracking speed is, but the worse the filtering effect is. Therefore, it is necessary to adjust the ratio coefficient k according to the simulation performance.

[0070] In another feasible embodiment, the first extended state observer adopts proportional integral differential control, and its principle steps are as follows:

[0071] First, by comparing the reference current value with the actual current value, the current feedback error is calculated. The error reflects the gap between the current performance of the system and the target state. Then, the integral term accumulates the historical feedback error. This process can effectively reduce the long-term steady-state error. For example, when the load condition is unstable, the integral term can gradually adjust the system output to ensure that the actual current value approaches the target value. At the same time, the differential term predicts the future error trend by evaluating the rate of change of the error. When the system faces sudden external disturbances, such as instantaneous changes in grid frequency or a sharp increase in equipment load, the differential term can provide timely adjustment feedback, so that the controller responds quickly and reduces system oscillations. In order to optimize the control effect, the selection of proportional coefficient, integral coefficient and differential coefficient will directly affect the dynamic performance and steady-state performance of the system. For example, increasing the proportional coefficient can improve the response speed of the system, but an excessively large proportional coefficient may cause oscillations. It is necessary to find the optimal value through simulation verification. By comprehensively considering the current value, historical accumulation and change trend of the feedback error, the current can be accurately tracked, the system's ability to suppress external disturbances can be enhanced, and the overall operation stability and reliability can be improved.

[0072] S3: Keep the rotor current constant and suppress subsynchronous oscillations.

[0073] Furthermore, maintaining the rotor current constant includes performing feedback control according to the feedback control output variable and the compensation process, and calculating the final control variable.

[0074] It should be noted that the suppression of subsynchronous oscillations includes the final control variables being used to control the voltage and current of the rotor-side converter.

[0075] It should also be noted that according to the total disturbance estimated by the ESO, feedback control is performed according to the compensation process to form the final control variable, which is expressed as:

[0076]

[0077] By expanding the total disturbance estimated by the state observer and combining it with the compensation process, a closed-loop control system is formed, which can adjust the control variables in real time to offset the subsynchronous current disturbance, thereby maintaining the stability of the rotor current. Traditional control methods are often difficult to cope with the uncertainty and nonlinear factors in the operation of wind turbines. The control strategy of the present invention can adapt to the uncertainty and nonlinear factors in the operation of wind turbines through the compensation process, ensuring that subsynchronous oscillations can be effectively suppressed even in the case of wind energy fluctuations and power grid disturbances.

[0078] Example 2, reference Figure 3-Figure 5 , which is an embodiment of the present invention, provides an auto-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0079] First, the actual wind power generation system in Guyuan, Hebei Province was taken as the research object. Subsynchronous oscillations have occurred in Guyuan, Hebei Province for many times. The system model is as follows: Figure 3 As shown in Figure 1, the wind farm in Guyuan, Hebei Province is mainly composed of 1.5 MW doubly-fed asynchronous generators. For the convenience of modeling, it is assumed that all wind turbines in the wind farm are doubly-fed asynchronous generators and the operating doubly-fed asynchronous generators are in the same state. When the operating conditions of the doubly-fed asynchronous generators in the wind farm are not much different, the entire wind farm can be equivalent to a doubly-fed wind turbine set. All doubly-fed asynchronous generators are connected in a radial manner through 0.69 / 35 / 220 kV. The system parameters are shown in Table 1.

[0080] Table 1 System parameters

[0081] symbol parameter value SB(MVA) Base capacity 300 rs(pu) Stator resistance 0.016 xs(pu) Stator leakage reactance 0.255 rr(pu) Rotor resistance 0.018 xr(pu) Rotor leakage reactance 0.222 xm(pu) Excitation reactance 15.710 CL(pu) Series compensation capacitor 0.040 RL1(pu) 220kV line resistance 0.030 LL1(pu) 220kV line reactance 0.170 RL2(pu) 500kV line resistance 0.020 LL2(pu) 500kV line resistance 0.100 XT1(pu) Transformer T1 leakage reactance 0.030 XT2(pu) Transformer T2 leakage reactance 0.070 XT3(pu) Transformer T3 leakage reactance 0.140

[0082] The extended state observer parameters are set as: b x =1,β 01x =100,β 02x =2 / h;

[0083] The nonlinear state error feedback parameters are set as: k = 10;

[0084] Considering the high probability of subsynchronous oscillation under low wind speed conditions, the wind speed is set to 6m / s in the simulation model, and the fixed series capacitor is kept in operation. When the system enters the steady state, a three-phase fault is introduced at t=4s (fault duration 0.02s) on the high-voltage side of the 220 / 500kv line transformer. The comparison between the PI controller and the active disturbance rejection control (ADRC) of the present invention is shown in Figure 2. Figure 4 and Figure 5 As shown by Figure 4 -(a) 500kV line active power and Figure 4 -(b) Reactive power of 500kV line It can be seen that the active power and reactive power of the PI controller in the 500kV line fluctuate greatly, especially when the load changes, the stability of the system is affected to a certain extent. The active disturbance rejection control method of the present invention shows a more stable dynamic response under the same conditions. Figure 4 -(c) q-axis component of rotor current and Figure 4 -(d) Rotor current d-axis component It can be seen that through the active disturbance rejection control of the present invention, the fluctuations of the q-axis and d-axis components of the rotor current are small, indicating that the suppression effect on subsynchronous oscillation is obvious. Figure 4 -(e) Line A phase current It can be seen that the fluctuation of phase A current can be used to judge the uniformity of system load distribution. Large fluctuations may cause equipment overload or other failures. The active disturbance rejection control of the present invention is more stable than the PI controller in the case of line A phase current fluctuation. Figure 5 -(a) PI control strategy line current spectrum. It can be seen that under the PI control strategy, the harmonic components of the line current, especially the energy concentration in the low-frequency band, indicate the existence of subsynchronous oscillation. Figure 5 -(b) It can be seen from the spectrum of the line current of the active disturbance rejection control that, compared with the PI control, after using the active disturbance rejection control of the present invention, the harmonic components in the spectrum are significantly reduced, especially the energy in the low-frequency region is significantly reduced, indicating the effectiveness of the active disturbance rejection control of the present invention in suppressing subsynchronous oscillations.

[0085] In summary, the active disturbance rejection control strategy of the present invention is superior to the traditional PI control strategy in terms of dynamic response and spectral characteristics, which provides an important basis for subsequent control optimization and system stability improvement. This shows that in the operation of doubly fed wind turbines, the use of active disturbance rejection control methods can effectively reduce the risk of subsynchronous oscillations and improve the reliability and operation efficiency of the overall system. Therefore, the present invention is creative.

[0086] Example 3, reference Figure 6 , which is an embodiment of the present invention, provides an auto-disturbance rejection control system for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator set, including an extended state observer module, a feedback control strategy module, and a rotor current constant control module.

[0087] The extended state observer module is used to estimate the subsynchronous current disturbance of the first controlled object in real time, and determine the state information and subsynchronous current disturbance of the system through the optimal control function according to the input and output of the first controlled object; the feedback control strategy module is used to perform feedback control according to the disturbance estimated by the extended state observer, calculate the feedback control output variable through the optimal control function and the current feedback error, and calculate the current feedback error according to the current reference value and the current state estimated in the extended state observer; the rotor current constant control module is used to keep the rotor current constant and suppress subsynchronous oscillation.

[0088] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0089] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0090] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0091] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc. It should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limited. Although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

[0092] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An auto-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator set, characterized in that: include: estimating a subsynchronous current disturbance of a first controlled object in real time through a first extended state observer; Using a first nonlinear state error feedback control strategy, feedback control is performed according to the disturbance estimated by the extended state observer; Keep the rotor current constant and suppress subsynchronous oscillations.

2. The method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to claim 1, characterized in that: The first extended state observer comprises determining the state information and the subsynchronous current disturbance of the system through an optimal control function according to the input and output of the first controlled object.

3. The method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to claim 2, characterized in that: The input of the first controlled object includes a rotor-side converter voltage and a rotor-side converter current.

4. The method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to claim 3, characterized in that: The first nonlinear state error feedback control strategy includes calculating a feedback control output variable through an optimal control function and a current feedback error.

5. The method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to claim 4, characterized in that: The performing feedback control according to the disturbance estimated by the extended state observer includes calculating a current feedback error by using a current reference value and a current state estimated in the extended state observer.

6. The method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to claim 5, characterized in that: The method of maintaining the rotor current constant includes performing feedback control according to the feedback control output variable and the compensation process, and calculating the final control variable.

7. The method for suppressing subsynchronous oscillation of a doubly-fed wind turbine according to claim 6, characterized in that: The method for suppressing subsynchronous oscillation includes using final control variables to control the voltage and current of the rotor-side converter.

8. A system using the auto-disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine generator set as claimed in any one of claims 1 to 7, characterized in that: It includes extended state observer module, feedback control strategy module and rotor current constant control module; The extended state observer module is used to estimate the subsynchronous current disturbance of the first controlled object in real time, and determine the state information of the system and the subsynchronous current disturbance through the optimal control function according to the input and output of the first controlled object; The feedback control strategy module is used to perform feedback control according to the disturbance estimated by the extended state observer, calculate the feedback control output variable through the optimal control function and the current feedback error, and calculate the current feedback error according to the current reference value and the current state estimated in the extended state observer; The rotor current constant control module is used to keep the rotor current constant and suppress subsynchronous oscillation.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the active disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine set according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the active disturbance rejection control method for suppressing subsynchronous oscillation of a doubly-fed wind turbine set according to any one of claims 1 to 7 are implemented.

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