Method, device and equipment for identifying parameters of doubly-fed wind turbine generator controller

Abstract

The doubly-fed wind turbine generator controller parameter identification method provided by the invention comprises the following steps: establishing a doubly-fed asynchronous generator set system model, and establishing a mathematical model of a doubly-fed wind turbine generator in a synchronous rotating coordinate system; setting a machine side variable current controller in the doubly-fed asynchronous generator set system model, and generating a machine side current transfer function equation containing control parameters; setting a grid-side converter controller in the doubly-fed asynchronous generator set system model, and generating a grid-side current transfer function equation containing control parameters; controlling measures according to faults; according to the doubly-fed wind turbine generator controller parameter identification method provided by the invention, the doubly-fed asynchronous generator set system model is established, the algorithm model is correspondingly generated according to the converter control structure and the fault control structure, and the parameter identification of the doubly-fed asynchronous generator set controller is realized by iteratively solving the nonlinear equation in the model. The control parameters with better fault ride-through response characteristics of the doubly-fed wind turbine generator are obtained, the result is accurate, and the practicability is high.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy power systems, and is particularly applicable to modeling of new energy power generation equipment in power systems, and more particularly to a method, device and equipment for identifying controller parameters of a doubly-fed wind turbine set. Background Art

[0002] In recent years, the proportion of renewable energy power generation in my country has been increasing. As one of the leading modes of renewable energy power generation, the large-scale construction of wind power generation is conducive to accelerating the process of building a new power system. As one of the mainstream models in the wind power market, the doubly-fed wind turbine has the advantages of large capacity, variable speed constant frequency, and low cost. At present, in the wind power market, many manufacturers have main circuit models with different structures and control structure models with different control methods for doubly-fed wind turbines. Many models cover the models of doubly-fed wind turbines in various wind farms across the country, and have the ability to characterize the fault ride-through characteristics of a single unit. However, due to intellectual property issues, the control structure and parameters in the electromagnetic transient model of the unit are unknown. This will result in the output of the model being unable to be adjusted by changing the control structure, so the identification of the converter control structure and model in the "black box" model has important theoretical and engineering significance.

[0003] Researchers have proposed a variety of solutions for parameter identification of doubly-fed wind turbines, such as: 1. Pan Xueping et al., “Frequency Domain Method for Parameter Identification of Doubly Fed Wind Turbine Grid-Side Controller”, Power System Technology, 2015, 39(03): 634-638 and “Frequency Domain Method for Decoupling Identification of Parameters of Doubly Fed Wind Turbine Rotor-Side Controller”, Automation of Electric Power Systems, 2015, 39(20): 19-25+108. The two papers decoupled the dq axis from the grid-side controller and the rotor-side controller respectively, and then superimposed a pseudo-random signal on the input signal, and identified the parameters of the grid-side controller and the rotor-side controller respectively through the natural rate spectrum of the input signal and the cross-power spectrum of the output signal.

[0004] 2. Xu Raoqi et al., “Study on Parameter Identification Method of Doubly Fed Wind Turbine Converter Based on M Sequence”, Power System Technology, 2022, 46(02): 578-586. This paper discretizes the transfer function of the controller of the doubly fed unit, constructs a discretization model, adds M sequence excitation to the input signal, identifies the controller parameters of the doubly fed unit through an optimization algorithm, and analyzes the impact of various fluctuations on the identification results.

[0005] 3. Guo Qiang et al., “Parameter Decoupling Identification Method for Low Voltage Ride Through Model of Direct Drive Power Generation System Considering Recovery Transient Process”, High Voltage Engineering, 2021, 47(10): 3430-3440. This article analyzes the PI parameters of the transient process of the direct drive power generation system under low voltage ride through. Considering the dq axis coupling problem of the current inner loop controller, the decoupling model of the controller is constructed. Finally, the optimization algorithm is used to identify the controller parameters under fault ride through, and the optimal parameters under different working conditions are analyzed and calculated.

[0006] In summary, at present, there have been some studies on the identification methods of control parameters of doubly-fed wind turbines. However, the method of deriving decoupling models for the grid-side controller and the rotor-side controller is more suitable for theoretical analysis. The identification method combined with the intelligent optimization algorithm is not comprehensive enough in identifying parameters. At the same time, due to the complexity of the identification process, the identification efficiency is low. Therefore, it is urgent to provide an identification method for the parameter identification of the converter controller of a doubly-fed wind turbine based on fault ride-through, which has fast identification time, accurate identification results, and high practicality for actual engineering. Summary of the invention The present invention provides a method for identifying controller parameters of a doubly-fed wind turbine set, builds a doubly-fed asynchronous generator set system model, and generates an algorithm model corresponding to a converter control structure and a fault ride-through control structure, and obtains control parameters with better fault ride-through response characteristics of the doubly-fed wind turbine set by iteratively solving nonlinear equations in the model. The method has accurate results and high practicability.

[0007] In a first aspect, an example of the present invention provides a method for identifying parameters of a doubly-fed wind turbine controller, the method comprising: A method for identifying parameters of a doubly-fed wind turbine controller, comprising: Build a doubly-fed asynchronous generator system model and establish a mathematical model of a doubly-fed wind turbine in a synchronous rotating coordinate system; A machine-side current converter controller is set in the double-fed asynchronous generator system model, and a machine-side current transfer function equation containing control parameters is generated; A grid-side current converter controller is provided in the double-fed asynchronous generator system model, and a grid-side current transfer function equation including control parameters is generated; According to the fault control strategy, the active current expression and reactive current expression of the doubly-fed wind turbine generator set are calculated; The output data of the voltage drop when a fault occurs is obtained, and the expressions of the active current and the reactive current are used as the objective function to solve the machine-side current transfer function equation and the grid-side current transfer function equation to obtain the optimal control parameters of the machine-side converter controller and the grid-side converter controller.

[0008] Optionally, the double-fed asynchronous generator system model includes: Wind turbines; A double-fed asynchronous generator connected to the wind turbine, wherein the double-fed asynchronous generator comprises a stator side and a rotor side, wherein the stator side is connected to a power grid; A back-to-back converter, which is arranged between the rotor side of the double-fed asynchronous generator and the power grid to provide rotor voltage excitation regulation; A chopper protection circuit is arranged in the double-fed asynchronous generator to form overvoltage protection; A neutral point voltage balancing control module is provided in the double-fed asynchronous generator to balance the voltages at both ends of the upper and lower buses of the back-to-back converter.

[0009] Optionally, the mathematical model of the doubly-fed wind turbine generator set includes: a stator mathematical equation, a rotor mathematical equation and a stator-rotor flux equation.

[0010] Optionally, the calculation of the generator-side current transfer function equation includes: Substitute the stator and rotor flux equations of the doubly-fed generator into the rotor mathematical equation to obtain the rotor voltage equation of the machine-side converter; Substituting the machine-side converter controller into the rotor voltage equation of the machine-side converter, an expression for the d-axis current and active power static difference of the machine-side converter and an expression for the q-axis current and reactive power static difference of the machine-side converter are obtained; The d-axis of the machine-side converter controller adopts a control strategy of a power outer loop and a current inner loop, and the q-axis of the machine-side converter controller adopts a control strategy of a reactive power outer loop and a current inner loop.

[0011] Optionally, the calculation of the grid-side current transfer function equation includes: Obtaining an AC voltage expression of the grid-side converter controller; Substituting the grid-side converter controller into the AC voltage expression of the grid-side converter controller, obtaining an expression for the d-axis current of the grid-side converter controller and the static difference of the DC bus voltage and a q-axis reactive current inner loop transfer function of the grid-side converter controller; The d-axis of the grid-side converter controller adopts a control strategy of a DC voltage outer loop and a current inner loop, and the q-axis of the grid-side converter adopts a current inner loop control strategy.

[0012] Optionally, the active current expression of the doubly-fed wind turbine generator set is:

[0013] in, is the active current that the doubly-fed wind turbine should generate during the fault period, is the reactive current that the doubly-fed wind turbine should generate during the fault period, is the steady-state value of active current before the fault, is the maximum current; The reactive current expression provided by the double-fed wind turbine is: ; in, is the reactive current increment that the doubly-fed wind turbine should generate during the fault period, is the reactive support coefficient, is the reactive voltage threshold, is the terminal voltage, is the rated current.

[0014] Optionally, the process of solving the optimal control parameters of the generator-side converter controller and the grid-side converter controller includes: According to the output data of the actual voltage drop, the active current and reactive current output data of the doubly-fed wind turbine generator set under the low voltage ride-through condition are extracted, and the fault strategy parameters are obtained by identifying the control formula of the active current and reactive current during the grid connection period; Injecting white noise sequence excitation into the feedback channels of the generator-side converter controller and the grid-side converter controller, initializing the PI parameters of the generator-side converter controller and the grid-side converter controller as populations, and taking a steady-state control model as an objective function; Iteratively solving through a differential evolution algorithm to obtain gain constants and integral constants of the machine-side converter controller and the grid-side converter controller, and outputting the fault strategy parameter, the gain constant and the integral constant as optimal control parameters; Among them, the feedback channels of the generator-side converter controller and the grid-side converter controller include: a generator-side converter controller d-axis feedback channel, a generator-side converter controller q-axis feedback channel, a grid-side converter controller d-axis feedback channel and a grid-side converter controller q-axis feedback channel.

[0015] In a second aspect, an embodiment of the present invention provides a doubly-fed wind turbine controller parameter identification device, the device comprising: A model building module, which is used to build a system model of a doubly-fed asynchronous generator set and establish a mathematical model of a doubly-fed wind turbine set in a synchronous rotating coordinate system; A machine-side control module, which is used to set a machine-side current converter controller in the double-fed asynchronous generator system model and generate a machine-side current transfer function equation containing control parameters; A grid-side control module, which is used to set a grid-side current converter controller in the double-fed asynchronous generator system model and generate a grid-side current transfer function equation containing control parameters; A calculation module, which is used to calculate the active current expression and reactive current expression of the doubly-fed wind turbine generator set according to the fault control strategy; A solution module is used to obtain output data of voltage drop when a fault occurs, take the expressions of active current and reactive current as objective functions, solve the machine-side current transfer function equation and the grid-side current transfer function equation, and obtain optimal control parameters of the machine-side converter controller and the grid-side converter controller.

[0016] In a third aspect, an embodiment of the present invention provides a doubly-fed wind turbine controller parameter identification device, comprising: one or more processors; a storage device for storing one or more programs, when the one or more programs are executed by the one or more processors, the one or more processors implement the method described in the first aspect.

[0017] In a fourth aspect, an embodiment of the present invention provides a storage medium having computer program instructions stored thereon, which implement the method described in the first aspect when the computer program instructions are executed by a processor.

[0018] In summary, an embodiment of the present invention provides a method for identifying controller parameters of a doubly-fed wind turbine set, builds a system model of a doubly-fed asynchronous generator set, and generates an algorithm model accordingly based on the converter control structure and the fault control structure. By iteratively solving the nonlinear equations in the model, control parameters with better fault ride-through response characteristics of the doubly-fed wind turbine set are obtained, and the results are accurate and highly practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 This is a flow chart of the method for identifying parameters of a doubly-fed wind turbine controller according to the present invention; Figure 2 It is the general main circuit structure of the doubly-fed wind turbine generator set described in the present invention; Figure 3 The rotor side controller and circuit equivalent control block diagram of the present invention; Figure 4 It is a grid-side current controller and circuit equivalent control block diagram of the present invention; Figure 5 This is a schematic diagram of excitation injection of the rotor side control system according to the present invention; Figure 6 This is a schematic diagram of the grid-side control system excitation injection according to the present invention; Figure 7The step-by-step parameter identification process based on the steady-state frequency domain model and the fault ride-through strategy described in the present invention; Figure 8 The rotor converter d-axis feedback channel of the present invention is superimposed with a white noise sequence. Input signal; Fig. 9 The q-axis feedback channel of the rotor converter of the present invention is superimposed with a white noise sequence. Input signal; Fig.10 The grid-side converter d-axis feedback channel of the present invention is superimposed with a white noise sequence. Input signal; Fig.11 The q-axis feedback channel of the grid-side converter of the present invention is superimposed with a white noise sequence. Overlay Feedback signal; Fig.12 It is a structural schematic diagram of the controller parameter identification device of the doubly-fed wind turbine set according to the present invention; Fig.13 It is a structural schematic diagram of the doubly-fed wind turbine controller parameter identification device described in the present invention. DETAILED DESCRIPTION

[0020] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0021] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0022] like Figure 1 As shown, based on the technical problem raised by the background technology, the present invention provides a method for identifying parameters of a doubly-fed wind turbine controller, comprising: Step S110, constructing a system model of a doubly-fed asynchronous generator set, and establishing a mathematical model of a doubly-fed wind turbine set in a synchronous rotating coordinate system; Step S120, setting a machine-side current converter controller in the doubly-fed asynchronous generator system model, and generating a machine-side current transfer function equation including control parameters; Step S130, setting a grid-side current converter controller in the doubly-fed asynchronous generator system model, and generating a grid-side current transfer function equation including control parameters; Step S140, calculating the active current expression and reactive current expression of the doubly-fed wind turbine generator set according to the fault control strategy; Step S150, obtaining output data of voltage drop when a fault occurs, taking expressions of active current and reactive current as objective functions, solving the machine-side current transfer function equation and the grid-side current transfer function equation, and obtaining optimal control parameters of the machine-side converter controller and the grid-side converter controller.

[0023] The controller parameter identification method for a doubly-fed wind turbine set provided by the present invention builds a doubly-fed asynchronous generator set system model, and generates an algorithm model accordingly based on a converter control structure and a fault control structure. By iteratively solving the nonlinear equations in the model, control parameters with better fault ride-through response characteristics of the doubly-fed wind turbine set are obtained, and the results are accurate and highly practical.

[0024] like Figure 2 As shown, in a preferred embodiment, the system model of the doubly fed asynchronous generator set includes: a wind turbine, a doubly fed asynchronous generator, a back-to-back converter for the power grid, a chopper protection circuit and a neutral point voltage balance control module; the doubly fed asynchronous generator is connected to the wind turbine, and the doubly fed asynchronous generator includes a stator side and a rotor side, and the stator side is connected to the power grid. The back-to-back converter is arranged between the rotor side of the doubly fed asynchronous generator and the power grid to provide rotor voltage excitation regulation; the chopper protection circuit is arranged in the doubly fed asynchronous generator to form overvoltage protection; the neutral point voltage balance control module is arranged in the doubly fed asynchronous generator to balance the voltages at both ends of the upper and lower busbars of the back-to-back converter. The general main circuit topology of the doubly fed wind turbine set proposed in the present invention is as follows: Figure 2 As shown. The wind turbine is connected to a doubly-fed asynchronous generator. The stator side of the motor is directly connected to the grid, and the rotor side is connected to the grid side through a back-to-back three-level converter (NPC) to provide rotor voltage excitation regulation. A general main circuit framework of a doubly-fed wind turbine is proposed. On the basis of the main circuit framework, a doubly-fed asynchronous generator model is built. Then a back-to-back converter is built. A neutral point clamped three-level converter (NPC) suitable for doubly-fed wind turbines is built. Finally, a protection circuit is built. Chopper becomes a doubly-fed wind turbine protection circuit because it can ensure continuous excitation of the converter after a short circuit fault occurs in the wind turbine. It is connected to both ends of the DC bus to maintain the stability of the DC bus voltage. It is usually composed of a group of switching devices and a load-unloading resistor. The mathematical model of the doubly-fed wind turbine includes: stator mathematical equations, rotor mathematical equations, and stator-rotor flux equations.

[0025] In the synchronous rotating coordinate system, the mathematical model of the dq axis voltage on the stator side can be expressed as: (1) in, and are the d-axis voltage and q-axis voltage on the stator side respectively; and are the d-axis current and q-axis current on the stator side respectively; , They are the d-axis flux and q-axis flux on the stator side respectively; is the stator resistance; is the stator side angular frequency.

[0026] In the synchronous rotating coordinate system, the mathematical model of the dq axis voltage on the rotor side can be expressed as: (2) in, and are the d-axis voltage and q-axis voltage on the rotor side respectively; and are the d-axis current and q-axis current on the rotor side respectively; , They are the d-axis flux and q-axis flux on the rotor side respectively; is the stator resistance; is the rotor side angular frequency.

[0027] The dq-axis flux can be expressed as: (3) (4) in, and are the stator inductance and rotor inductance respectively, is the magnetizing inductance.

[0028] like Figure 3 As shown in the figure, a machine-side current converter controller is set in the doubly-fed asynchronous generator system model, and a machine-side current transfer function equation containing control parameters is generated; a generalized machine-side controller is proposed. Its main function is to control active power. The difference between the active power reference value and the actual value is adjusted by the controller as the d-axis current The reference value is connected to the current inner loop. The same is true for reactive power. The calculation of the machine-side current transfer function equation includes: Substitute the stator-rotor flux equation of the doubly-fed generator into the rotor mathematical equation to obtain the rotor voltage equation of the machine-side converter; that is, substitute the stator-rotor flux equation of the doubly-fed generator into the rotor voltage equation to obtain the rotor voltage equation of the machine-side converter, which can be expressed as follows in the synchronous coordinate system: (5) in, .

[0029] In formula (5), the d-axis of the AC voltage of the machine-side converter contains the q-axis component, and the q-axis contains the d-axis component. It is necessary to add a decoupling device to the controller to eliminate the influence of the dq-axis coupling on the simulation speed and simulation accuracy. Figure 3 As shown, by feedforward decoupling the coupling term in the dq axis and then connecting the PI controller, coupling in the AC voltage of the grid-side converter can be achieved.

[0030] Figure 3 middle: is the reference value of the d-axis machine-side current, is the reference value of the q-axis machine-side current, is the proportional coefficient of the inner loop controller of the machine side current, is the integral coefficient of the inner loop controller of the machine side current.

[0031] Substituting the machine-side converter controller into the rotor voltage equation of the machine-side converter, the expressions for the d-axis current and active power static error of the machine-side converter are obtained. The d-axis of the machine-side converter adopts the control strategy of active power outer loop and current inner loop. Substituting the active power outer loop PI controller into equation (5), the expressions for the d-axis current and active power static error of the machine-side converter are obtained: (6) in, is the proportional coefficient of the active power outer loop controller, is the integral coefficient of the active power outer loop controller. , is the stator active power reference value, is the stator active power.

[0032] The q-axis of the machine-side converter adopts the control strategy of reactive power outer loop and current inner loop. Substituting the reactive power outer loop PI controller into equation (5), the expression of the q-axis current and reactive power static difference of the machine-side converter is obtained: (7) in, is the proportional coefficient of the reactive power outer loop controller, is the integral coefficient of the reactive power outer loop controller. , is the stator reactive power reference value, is the stator reactive power.

[0033] Step S130, set the grid-side converter controller in the doubly-fed asynchronous generator system model, generate the grid-side current transfer function equation containing the control parameters, and propose a generalized grid-side converter controller. The calculation of the grid-side current transfer function equation includes: obtaining the AC voltage expression of the grid-side converter controller; substituting the grid-side converter controller into the AC voltage expression of the grid-side converter controller to obtain the expression of the d-axis current of the grid-side converter controller and the static difference of the DC bus voltage and the q-axis reactive current inner loop transfer function of the grid-side converter controller; wherein, the d-axis of the grid-side converter controller adopts the control strategy of the DC voltage outer loop and the current inner loop, and its main function is to control the DC bus voltage and the bidirectional flow of active power and reactive power between the motor rotor and the power grid. In the synchronous coordinate system, the AC voltage of the grid-side converter can be expressed as: (8) in, , are the d-axis and q-axis voltages of the power grid respectively, , They are the d-axis and q-axis currents of the grid-side controller respectively. , They are the d-axis and q-axis voltages at the converter outlet respectively. and is the filter resistance and reactance, is the stator side angular frequency.

[0034] In formula (8), the d-axis of the grid-side converter AC voltage contains the q-axis component, and the q-axis contains the d-axis component. It is necessary to add a decoupling device to the controller to eliminate the influence of the dq-axis coupling on the simulation speed and simulation accuracy. Figure 4 As shown, by feedforward decoupling the coupling term in the dq axis and then connecting the PI controller, coupling in the AC voltage of the grid-side converter can be achieved.

[0035] Figure 4 middle: is the reference value of the grid-side current of the d-axis, is the reference value of the grid-side current of the q-axis, is the proportional coefficient of the grid-side current inner loop controller, is the integral coefficient of the grid-side current inner loop controller.

[0036] The grid-side converter d-axis adopts a control strategy of DC voltage outer loop and current inner loop. Substituting the DC voltage outer loop PI controller into equation (8), the expression of the grid-side converter d-axis current and DC bus voltage static difference is obtained: (9) in, is the proportional coefficient of the DC voltage outer loop controller, is the integral coefficient of the DC voltage outer loop controller. , is the DC voltage reference value, is a DC voltage. is the power coefficient, which is numerically equal to .

[0037] During the fault period, the reactive power reference value of the grid-side converter is 0, so the q-axis control strategy of the grid-side converter is the current inner loop, and the grid-side reactive current inner loop transfer function is: (10) According to the fault control strategy, the active current expression and reactive current expression of the doubly-fed wind turbine are calculated; according to the grid connection standard, when a voltage drop fault occurs in the power grid, the wind turbine will respond quickly from the moment the voltage drop occurs, and support voltage recovery by injecting reactive current. The reactive current expression provided by the wind turbine is: (11) in, is the reactive current increment that the doubly-fed wind turbine should generate during the fault period, is the reactive support coefficient, is the reactive voltage threshold, is the terminal voltage, is the rated current.

[0038] Due to the limitation of the maximum current value, when the reactive current increases, the active current will change with the reactive current. At the same time, the size of the active output before the fault will limit the size of the active current. When the voltage drops in the doubly fed wind turbine, the active current responds quickly. The expression of the active current in the wind turbine is: (12) in, is the active current that the doubly-fed wind turbine should generate during the fault period, is the reactive current that the doubly-fed wind turbine should generate during the fault period, is the steady-state value of active current before the fault, is the maximum current.

[0039] In step S150, the output data of the voltage drop when the fault occurs is obtained, the expressions of active current and reactive current are used as objective functions, the machine-side current transfer function equation and the grid-side current transfer function equation are solved, and the optimal control parameters of the machine-side converter controller and the grid-side converter controller are obtained.

[0040] The present invention adopts a search algorithm with both robustness and global optimization capability, the differential evolution algorithm, as an optimization algorithm for the identification of control parameters of a doubly-fed wind turbine. The method first divides the fault controller parameters of the doubly-fed wind turbine when a voltage drop occurs into fault strategy parameters and PI parameters in the controller. The differential evolution algorithm process is as follows: 1. Generate the initial population Randomly generate M individuals that meet the constraints in n-dimensional space. The implementation measures are as follows: (13) in and They are The upper and lower bounds of each individual; is a random number between [0,1].

[0041] 2. Mutation Operation Randomly select 3 individuals from the population , and ,and , then the basic mutation operation is: (14) in is the mutation term. This differential operation is the key to the differential evolution algorithm. is the variation factor; A pseudo-random integer representing the sequence number of the entire individual in the population; The best individual in the contemporary population.

[0042] 3. Crossover Operation The crossover operation is to determine how to increase the diversity of the population. The specific operation is: (15) Among them, CR is the crossover factor, CR∈[0,1].

[0043] 4. Select an action To determine Becoming a member of the next generation, and Comparing the evaluation functions (16) Repeat steps 2 to 4 until the maximum number of iterations is reached. .

[0044] like Figure 7 The identification process is shown in the figure. The specific identification method is as follows: 1. Based on the output data of the actual voltage drop, the expressions of active current and reactive current during the fault period are used as the objective function to identify the fault strategy parameters; 2. The controller PI parameters are used as the population and initialized, and the steady-state control model is used as the objective function; 3. Inject white noise sequence excitation into the feedback channel; 4. Through the differential evolution algorithm, the gain constant and integral constant in the controller PI are obtained through iterative solution.

[0045] According to the output data of the actual voltage drop, the active current and reactive current output data of the doubly-fed wind turbine generator set under the low voltage ride-through condition are extracted, and the fault strategy parameters are obtained by identifying the control formula of the active current and reactive current during the grid connection period; Inject white noise sequence excitation into the feedback channel of the generator-side converter controller and the grid-side converter controller, use the PI parameters of the generator-side converter controller and the grid-side converter controller as the population and initialize them, and use the steady-state control model as the objective function; The differential evolution algorithm is used to iteratively solve the gain constant and integral constant of the generator-side converter controller and the grid-side converter controller, and the fault strategy parameters, gain constant and integral constant are output as optimal control parameters. Among them, the feedback channels of the machine-side converter controller and the grid-side converter controller include: a d-axis feedback channel of the machine-side converter controller, a q-axis feedback channel of the machine-side converter controller, a d-axis feedback channel of the grid-side converter controller and a q-axis feedback channel of the grid-side converter controller.

[0046] This paper takes the electromagnetic transient model of the doubly-fed wind turbine on Matlab / Simulink as the benchmark and uses the differential evolution algorithm to identify its control parameters. The model has a rated capacity of 1.5MW, a wind turbine outlet voltage of 690V, a DC bus voltage reference value of 1050V, and a rated speed of 1750r / min. The parameters of the doubly-fed wind turbine are shown in Table 1.

[0047] Table 1 is a parameter table of the double-fed wind turbine generator system of the present invention.

[0048] 1. Fault control strategy parameter identification and verification according to Figure 7 In the identification process shown in Figure 2, the control strategy parameters are first identified. The identification process uses the expressions of reactive current and active current during the fault as the objective function. By adding a three-phase short-circuit fault on the grid-connected side, the voltage, active power, reactive power, active current and reactive current response data of the double-fed wind turbine model under the voltage sag fault are fitted according to the objective function. The control strategy parameters under the voltage sag fault are obtained as shown in Table 2, where is the reactive support coefficient, is the reactive voltage threshold, is the maximum current.

[0049] Table 2 Control strategy parameters under voltage drop fault

[0050] 2. Controller parameter identification and verification After completing the control strategy parameter identification, the PI controller parameters in the machine-side converter and the grid-side converter of the unit are identified. Using equations (6)-(9) as the objective function, the machine-side controller d-axis active power outer loop controller parameters, current inner loop controller parameters, q-axis reactive power outer loop controller parameters, current inner loop controller parameters, grid-side controller d-axis DC voltage outer loop controller parameters, current inner loop controller parameters, and grid-side controller q-axis current inner loop controller parameters are identified using the differential evolution algorithm.

[0051] (1) Machine side controller d axis The white noise sequence is superimposed on the d-axis feedback channel of the machine-side converter, and the proportional coefficient of the d-axis active power outer loop controller of the machine-side controller is obtained through multiple iterations. and the integral coefficient , current inner loop controller proportional coefficient and the integral coefficient . That is, the signal of the difference between the active power reference value and the measured value is as follows Figure 8 As shown, Figure 8 The signal is used as the input signal of formula (6), and the identification results are shown in Table 3.

[0052] Table 3 is the d-axis coefficient table of the machine-side controller

[0053] (2) Machine side controller q axis The white noise sequence is superimposed on the q-axis feedback channel of the machine-side converter, and the proportional coefficient of the q-axis reactive power outer loop controller of the machine-side controller is obtained through multiple iterations. and the integral coefficient , current inner loop controller proportional coefficient and the integral coefficient . That is, the signal of the difference between the reactive power reference value and the measured value is as follows Fig. 9 As shown, Fig. 9 The signal is used as the input signal of formula (7), and the identification results shown in Table 4 are obtained.

[0054] Table 4 is the q-axis coefficient table of the machine-side controller

[0055] (3) Grid-side controller d-axis The white noise sequence is superimposed on the d-axis feedback channel of the grid-side converter, and the proportional coefficient of the d-axis DC voltage outer loop controller of the grid-side controller is obtained through multiple iterations. and the integral coefficient , current inner loop controller proportional coefficient and the integral coefficient . That is, the signal of the difference between the DC bus voltage reference value and the measured value is as follows Fig.10 As shown, Fig.10 The signal is used as the input signal of formula (9), and the identification results shown in Table 5 are obtained.

[0056] Table 5 is the d-axis coefficient table of the grid-side converter

[0057] (4) Grid-side controller q-axis A white noise sequence is superimposed on the q-axis feedback channel of the grid-side converter, and the proportional coefficient of the q-axis current inner loop controller of the grid-side controller is obtained through multiple iterations. and the integral coefficient The noise signal is Fig.11 As shown, Fig.11 The signal is used as the input signal of formula (10), and the identification results shown in Table 6 are obtained.

[0058] Table 6 is the grid-side controller q-axis proportional coefficient table

[0059] The present invention establishes the main circuit, converter control structure, fault control structure and control parameter identification method based on differential evolution algorithm of the doubly fed wind turbine. In terms of the main circuit, a back-to-back parallel converter unique to the doubly fed wind turbine is designed. The stator side of the doubly fed asynchronous generator is directly connected to the power grid. The back-to-back parallel converter adopts a three-level converter, and the neutral point potential balance control is used to balance the upper and lower bus voltages. In terms of the control circuit, a symmetrical and asymmetrical high and low voltage fault ride-through control logic suitable for doubly fed wind turbines is proposed. A step-by-step parameter identification method based on differential evolution algorithm is proposed. The method of the present invention is simple and practical, and can iteratively solve the nonlinear equations in the model to find control parameters with better fault ride-through response characteristics for doubly fed wind turbines, which has practical engineering significance for the modeling and fault control of doubly fed wind turbines.

[0060] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

[0061] like Fig.12 As shown, a structural block diagram of a doubly-fed wind turbine controller parameter identification device provided by an embodiment of the present invention, the device is used to execute the doubly-fed wind turbine controller parameter identification method provided by the above data receiving end embodiment, and has functional modules and beneficial effects corresponding to the execution method. The device includes: a model building module 410, a machine-side control module 420, a grid-side control module 430, a calculation module 440 and a solution module 450.

[0062] The model building module 410 is used to build a system model of a doubly-fed asynchronous generator set and establish a mathematical model of a doubly-fed wind turbine set in a synchronous rotating coordinate system; The machine-side control module 420 is used to set a machine-side current converter controller in the double-fed asynchronous generator system model and generate a machine-side current transfer function equation containing control parameters; The grid-side control module 430 is used to set a grid-side current converter controller in the double-fed asynchronous generator system model and generate a grid-side current transfer function equation containing control parameters; The calculation module 440 is used to calculate the active current expression and reactive current expression of the doubly-fed wind turbine generator set according to the fault control strategy; The solution module 450 is used to obtain the output data of the voltage drop when a fault occurs, take the expressions of active current and reactive current as the objective function, solve the machine-side current transfer function equation and the grid-side current transfer function equation, and obtain the optimal control parameters of the machine-side converter controller and the grid-side converter controller.

[0063] A structural diagram of a doubly-fed wind turbine controller parameter identification device provided by an embodiment of the present invention is shown in FIG. Fig.13 As shown, the device includes a processor 510, a memory 520, an input device 530, and an output device 540; the number of processors 510 in the device can be one or more. Fig.13 A processor 510 is taken as an example; the processor 510, the memory 520, the input device 530 and the output device 540 in the device can be connected via a bus or other means. Fig.13In the example, the connection through the bus is taken. The memory 520, as a computer-readable storage medium, can be used to store software programs, computer executable programs and modules, such as program instructions / modules corresponding to the networking transmission method according to data delay in the embodiment of the present invention. The processor 510 executes various functional applications and data processing of the device by running the software programs, instructions and modules stored in the memory 520, that is, realizes the above-mentioned networking transmission method according to data delay. The input device 530 can be used to receive input digital or character information, and generate key signal input related to user settings and function control of the device. The output device 540 may include display devices such as display screens.

[0064] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

[0065] An embodiment of the present invention further provides a storage medium comprising computer executable instructions, wherein the computer executable instructions are used to execute a method for identifying parameters of a doubly-fed wind turbine controller when executed by a computer processor, the method comprising: Build a doubly-fed asynchronous generator system model, and establish a mathematical model of the doubly-fed wind turbine in a synchronous rotating coordinate system; set a machine-side converter controller in the doubly-fed asynchronous generator system model, and generate a machine-side current transfer function equation containing control parameters; set a grid-side converter controller in the doubly-fed asynchronous generator system model, and generate a grid-side current transfer function equation containing control parameters; calculate the active current expression and reactive current expression of the doubly-fed wind turbine according to the fault control strategy; obtain the output data of the voltage drop when the fault occurs, take the expressions of active current and reactive current as the objective function, solve the machine-side current transfer function equation and the grid-side current transfer function equation, and obtain the optimal control parameters of the machine-side converter controller and the grid-side converter controller.

[0066] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0067] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0068] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0069] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0070] Finally, 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 above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for identifying parameters of a doubly-fed wind turbine controller, characterized in that: include: Build a system model of a doubly-fed asynchronous generator set and establish a mathematical model of a doubly-fed wind turbine set in a synchronous rotating coordinate system; A machine-side current converter controller is set in the double-fed asynchronous generator system model, and a machine-side current transfer function equation containing control parameters is generated; A grid-side current converter controller is provided in the double-fed asynchronous generator system model, and a grid-side current transfer function equation including control parameters is generated; According to the fault control strategy, the active current expression and reactive current expression of the doubly-fed wind turbine generator set are calculated; The output data of the voltage drop when a fault occurs is obtained, and the expressions of the active current and the reactive current are used as objective functions to solve the machine-side current transfer function equation and the grid-side current transfer function equation to obtain the optimal control parameters of the machine-side converter controller and the grid-side converter controller.

2. The method for identifying parameters of a doubly-fed wind turbine controller according to claim 1, characterized in that: The double-fed asynchronous generator system model includes: Wind turbines; A double-fed asynchronous generator connected to the wind turbine, wherein the double-fed asynchronous generator comprises a stator side and a rotor side, wherein the stator side is connected to a power grid; A back-to-back converter, which is arranged between the rotor side of the double-fed asynchronous generator and the power grid to provide rotor voltage excitation regulation; A chopper protection circuit is arranged in the double-fed asynchronous generator to form overvoltage protection; A neutral point voltage balancing control module is provided in the double-fed asynchronous generator to balance the voltages at both ends of the upper and lower buses of the back-to-back converter.

3. The method for identifying parameters of a doubly-fed wind turbine controller according to claim 2, characterized in that: The mathematical model of the doubly-fed wind turbine generator set includes: a stator mathematical equation, a rotor mathematical equation and a stator-rotor flux equation.

4. The method for identifying parameters of a doubly-fed wind turbine controller according to claim 3, characterized in that: The calculation of the machine-side current transfer function equation includes: Substitute the stator and rotor flux equations of the doubly-fed generator into the rotor mathematical equation to obtain the rotor voltage equation of the machine-side converter; Substituting the machine-side converter controller into the rotor voltage equation of the machine-side converter, an expression for the d-axis current and active power static difference of the machine-side converter and an expression for the q-axis current and reactive power static difference of the machine-side converter are obtained; The d-axis of the machine-side converter controller adopts a control strategy of a power outer loop and a current inner loop, and the q-axis of the machine-side converter controller adopts a control strategy of a reactive power outer loop and a current inner loop.

5. The method for identifying parameters of a doubly-fed wind turbine controller according to claim 4, characterized in that: The calculation of the grid-side current transfer function equation includes: Obtaining an AC voltage expression of the grid-side converter controller; Substituting the grid-side converter controller into the AC voltage expression of the grid-side converter controller, obtaining an expression for the d-axis current of the grid-side converter controller and the static difference of the DC bus voltage and a q-axis reactive current inner loop transfer function of the grid-side converter controller; The grid-side converter controller d-axis adopts a control strategy of a DC voltage outer loop and a current inner loop, and the grid-side converter q-axis adopts a current inner loop control strategy.

6. The method for identifying parameters of a doubly-fed wind turbine controller according to claim 1, characterized in that: The active current expression of the double-fed wind turbine generator set is: ； in, is the active current that the doubly-fed wind turbine should generate during the fault period, is the reactive current that the doubly-fed wind turbine should generate during the fault period, is the steady-state value of active current before the fault, is the maximum current; The reactive current expression provided by the double-fed wind turbine is: ； in, is the reactive current increment that the doubly-fed wind turbine should generate during the fault period, is the reactive support coefficient, is the reactive voltage threshold, is the terminal voltage, is the rated current.

7. The method for identifying parameters of a doubly-fed wind turbine controller according to claim 1, characterized in that: The process of solving the optimal control parameters of the generator-side converter controller and the grid-side converter controller includes: According to the output data of the actual voltage drop, the active current and reactive current output data of the doubly-fed wind turbine generator set under the low voltage ride-through condition are extracted, and the fault strategy parameters are obtained by identifying the control formula of the active current and reactive current during the grid connection period; Injecting white noise sequence excitation into the feedback channels of the generator-side converter controller and the grid-side converter controller, initializing the PI parameters of the generator-side converter controller and the grid-side converter controller as populations, and taking a steady-state control model as an objective function; Iteratively solving through a differential evolution algorithm to obtain gain constants and integral constants of the machine-side converter controller and the grid-side converter controller, and outputting the fault strategy parameter, the gain constant and the integral constant as optimal control parameters; Among them, the feedback channels of the generator-side converter controller and the grid-side converter controller include: a generator-side converter controller d-axis feedback channel, a generator-side converter controller q-axis feedback channel, a grid-side converter controller d-axis feedback channel and a grid-side converter controller q-axis feedback channel.

8. A doubly-fed wind turbine controller parameter identification device, characterized in that: The device comprises: A model building module, which is used to build a system model of a doubly-fed asynchronous generator set and establish a mathematical model of a doubly-fed wind turbine set in a synchronous rotating coordinate system; A machine-side control module, which is used to set a machine-side current converter controller in the double-fed asynchronous generator system model and generate a machine-side current transfer function equation containing control parameters; A grid-side control module, which is used to set a grid-side current converter controller in the double-fed asynchronous generator system model and generate a grid-side current transfer function equation containing control parameters; A calculation module, which is used to calculate the active current expression and reactive current expression of the doubly-fed wind turbine generator set according to the fault control strategy; A solution module is used to obtain output data of voltage drop when a fault occurs, take the expressions of active current and reactive current as objective functions, solve the machine-side current transfer function equation and the grid-side current transfer function equation, and obtain optimal control parameters of the machine-side converter controller and the grid-side converter controller.

9. A doubly-fed wind turbine controller parameter identification device, characterized in that: The device comprises: one or more processors; a storage device for storing one or more programs, When the one or more programs are executed by the one or more processors, the one or more processors implement the method according to any one of claims 1 to 7.

10. A storage medium having computer program instructions stored thereon, characterized in that: When the computer program instructions are executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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