Fully dynamic direct-drive wind turbine impedance modeling method and system

Abstract

The present invention relates to the technical field of wind power generation, and specifically provides a full-dynamic direct-drive wind turbine impedance modeling method and system, performs small signal linearization on wind turbine torque and electromagnetic torque, constructs the motion equation of a single mass block of a direct-drive wind turbine, and analyzes the mechanical dynamics of the speed small signal. Subsequently, the speed dynamics of the permanent magnet synchronous motor and the machine-side converter are analyzed, and small signal models of the two are established. Using these small signal models, a small signal model of the electromagnetic torque and its command value is further constructed. The integral of the mechanical dynamic function is calculated through the electromagnetic torque model, and the conversion relationship between the armature current and the motor terminal voltage is established considering the coordinate system angle difference, and the impedance model of the direct-drive wind turbine considering the mechanical dynamics is constructed based on the conversion relationship. The present invention constructs an accurate impedance model.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power generation, and in particular relates to a method and system for modeling impedance of a full-dynamic direct-drive wind turbine set. Background Art

[0002] Wind energy, as a shining star in the field of renewable energy, has significantly extended its development trajectory from land to the vast ocean in recent years, showing vigorous vitality. Direct-drive wind turbines based on permanent magnet synchronous motors have become leaders in the field of offshore wind power with their high cost-effectiveness, excellent conversion efficiency and strong output power capacity. However, offshore wind farms are often isolated overseas, separated from the grid access point by a long power transmission corridor. This geographical feature makes offshore wind power frequently cause broadband oscillation events when connected to a relatively weak grid system, posing a severe challenge to the safe and stable operation of the power system, and also restricting the effective integration and utilization of new energy.

[0003] In the journey of exploring the stability of renewable energy grid connection, the state space method and the impedance method, as two major analysis tools, each play an important role. The state space method, with its accurate analysis of the system characteristic roots, can deeply reveal the stability nature of the grid-connected system, but its dependence on the detailed control structure and parameters of the system (i.e., the white box model requirement) is often difficult to be widely used in practice due to the protection barriers of commercial secrets. In contrast, the impedance method has become the preferred solution for the grid-connected stability analysis of renewable energy power generation equipment due to its unique advantage - wide compatibility with "black box" and "gray box" models.

[0004] When using the impedance method to evaluate the stability of the grid-connected system, building an accurate impedance model is the cornerstone to ensure the reliability of the analysis results. Unfortunately, the current impedance modeling practice for direct-drive wind turbines focuses more on the dynamic characteristics of the electrical level, and intentionally or unintentionally ignores the complex influence of the mechanical dynamics of the wind turbine (covering key elements such as speed fluctuations and pitch angle adjustment). Although this simplified processing is easy to operate, it inevitably weakens the comprehensiveness and accuracy of the impedance model, which may mislead the judgment of system stability and lay hidden dangers for the stable operation of the power system. Therefore, in the field of impedance modeling of direct-drive wind turbines in the future, it is urgent to strengthen the comprehensive consideration of mechanical dynamics and electrical dynamics, so as to build a model that is closer to reality and more accurate in prediction, and to safeguard the healthy development of offshore wind power. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a full-dynamic direct-drive wind turbine impedance modeling method and system to solve the above-mentioned technical problems.

[0006] In a first aspect, the present invention provides a full-dynamic direct-drive wind turbine impedance modeling method, comprising:

[0007] By linearizing the torque and electromagnetic torque of the wind turbine in small signals, the motion equation of the single mass block of the direct-drive wind turbine is constructed, and the mechanical dynamic function of the small speed signal is analyzed based on the motion equation;

[0008] Based on the mechanical dynamic function of the speed small signal, the speed dynamics of the permanent magnet synchronous motor and the machine-side converter are analyzed, and the permanent magnet synchronous motor small signal model and the machine-side converter small signal model are constructed based on the analysis results;

[0009] Based on the permanent magnet synchronous motor small signal model and the machine-side converter small signal model, an electromagnetic torque small signal model and an electromagnetic torque command value small signal model are constructed;

[0010] Based on the electromagnetic torque small signal model, the integral value of the mechanical dynamic function of the speed small signal is calculated, the angle difference between the controller coordinate system and the actual coordinate system of the machine-side converter is introduced, and the conversion relationship between the armature and the current and the coordinate system conversion relationship between the motor terminal voltage are constructed;

[0011] An impedance model of a direct-drive wind turbine considering mechanical dynamics is constructed based on the small signal model of the electromagnetic torque command value, the conversion relationship between the armature and the current, and the coordinate system conversion relationship of the motor terminal voltage.

[0012] In an optional embodiment, the torque and electromagnetic torque of the wind turbine are linearized by small signals to construct the motion equation of the single mass block of the direct-drive wind turbine group, and the mechanical dynamic function of the small speed signal is analyzed based on the motion equation, including:

[0013] The torque of the wind turbine It is expressed as:

[0014] ;

[0015] In the formula, is the air density, is the blade length, is the wind speed, is the pitch angle, is the tip speed ratio and , C T is the torque coefficient;

[0016] If the wind speed remains unchanged, the torque of the wind turbine is linearized by a small signal, and the result is:

[0017] ;

[0018] in, A small signal quantity representing a physical quantity, is the mechanical speed of the wind turbine;

[0019] The small signal of the pitch angle is:

[0020] ;

[0021] Among them, G pa1 (s) is the transfer function of the PI controller in the pitch control system, G pa2 (s) is the wind turbine pitch angle control transfer function, s is the complex frequency domain Laplace operator;

[0022] Small signal linearization of electromagnetic torque:

[0023] ;

[0024] Among them, G wm (s) is the wind turbine torque control transfer function;

[0025] The single mass module is used to characterize the shaft system of the direct-drive wind turbine. The motion equation of the single mass block is:

[0026] ;

[0027] Where J is the moment of inertia, is the friction damping torque, and , is the electrical speed, D m is the damping coefficient;

[0028] Linearize the single mass fast equation of the direct-drive wind turbine and substitute the wind turbine torque small signal equation into it to obtain:

[0029] ;

[0030] Define the mechanical time constant:

[0031] ;

[0032] Where, p is the number of motor pole pairs;

[0033] Substituting the small signal of the pitch angle into the single mass fast model equation, we get:

[0034] ;

[0035] make , and obtain the mechanical dynamic function of the small speed signal:

[0036] .

[0037] In an optional implementation, based on the mechanical dynamic function of the speed small signal, the speed dynamics of the permanent magnet synchronous motor and the machine-side converter are analyzed, and based on the analysis results, a permanent magnet synchronous motor small signal model and a machine-side converter small signal model are constructed, including:

[0038] Based on the small signal of the motor equation, the small signal of the speed is taken to obtain the small signal model of the permanent magnet synchronous motor:

[0039] ;

[0040] in, is the small signal quantity of the d-axis component of the output voltage of the machine-side converter in the actual dq coordinate system; is the small signal quantity of the q-axis component of the output voltage of the machine-side converter in the actual dq coordinate system; is the small signal quantity of the d-axis component of the output current of the machine-side converter in the actual dq coordinate system; is the small signal quantity of the q-axis component of the output current of the machine-side converter in the actual dq coordinate system; is the q-axis component of the inductance, is the d-axis component of the inductance; is the permanent magnet flux of the motor;

[0041] definition ;

[0042] , is the vector representation of the small speed signal;

[0043] The control equation of the machine-side converter is linearized by small signal:

[0044] ;

[0045] in, It is the small signal quantity of the d-axis component of the voltage of the machine-side converter in the dq coordinate system of the controller; It is the small signal quantity of the q-axis component of the voltage of the machine-side converter in the controller dq coordinate system; It is the small signal quantity of the d-axis component of the current of the machine-side converter in the controller dq coordinate system; is the small signal quantity of the q-axis component of the current of the machine-side converter in the controller dq coordinate system; G md,inner is the d-axis current control transfer function of the inner loop of the generator-side converter, G mq,inner is the q-axis current control transfer function of the inner loop of the machine-side converter; is the small signal value of the d-axis current command value of the machine-side converter in the controller dq coordinate system; is the small signal value of the q-axis current command value of the machine-side converter in the controller dq coordinate system;

[0046] definition .

[0047] In an optional implementation, an electromagnetic torque small signal model and an electromagnetic torque command value small signal model are constructed based on a permanent magnet synchronous motor small signal model and a machine-side converter small signal model, including:

[0048] The torque equation of a permanent magnet synchronous motor is:

[0049] ;

[0050] Among them, i mq is the q-axis component of the current of the machine-side converter, i md is the d-axis component of the current of the machine-side converter;

[0051] Taking a small signal of the torque equation, we get the electromagnetic torque small signal model:

[0052] ;

[0053] Convert the electromagnetic torque small signal model into a matrix:

[0054] ;

[0055] ;

[0056] Construct a small signal model of electromagnetic torque command value:

[0057] If the maximum torque current ratio control is adopted, the conversion function from the electromagnetic torque small signal to the current command value small signal is:

[0058] ;

[0059] Where p represents the number of motor pole pairs;

[0060] If 0d-axis current control is adopted, the conversion function from the electromagnetic torque small signal to the current command value small signal is:

[0061] .

[0062] In an optional implementation, the integral value of the mechanical dynamic function of the speed small signal is obtained based on the electromagnetic torque small signal model, the angle difference between the controller coordinate system and the actual coordinate system of the machine-side converter is introduced, and the conversion relationship between the armature and the current and the coordinate system conversion relationship of the motor terminal voltage are constructed, including:

[0063] Integrate the mechanical dynamic function of the speed small signal to obtain the small signal value of the electrical rotor angle:

[0064] ;

[0065] Substitute the electromagnetic torque small signal model into the mechanical dynamic function of the speed small signal;

[0066] Considering the angle difference between the machine-side converter control coordinate system cs and the actual coordinate system es, the conversion relationship of the motor armature current is:

[0067] ;

[0068] ;

[0069] Where E is a two-dimensional identity matrix;

[0070] The conversion relationship between the motor terminal voltage in the controller's dq coordinate system and the actual dq coordinate system is:

[0071] ;

[0072] ;

[0073] If the permanent magnet synchronous motor is a hidden pole machine, then :

[0074] ;

[0075] .

[0076] In an optional implementation, an impedance model of a direct-drive wind turbine generator system considering mechanical dynamics is constructed based on a small signal model of an electromagnetic torque command value, a conversion relationship between an armature and a current, and a coordinate system conversion relationship of a motor terminal voltage, including:

[0077] Construct an impedance model of a direct-drive wind turbine considering mechanical dynamics:

[0078] ;

[0079] ;

[0080] in,

[0081] ; ;

[0082] .

[0083] In a second aspect, the present invention provides a full-dynamic direct-drive wind turbine impedance modeling system, comprising:

[0084] The first construction module is used to construct the motion equation of the single mass block of the direct-drive wind turbine group by linearizing the small signal of the torque and electromagnetic torque of the wind turbine, and analyze the mechanical dynamic function of the small signal of the speed based on the motion equation;

[0085] The second construction module is used to analyze the speed dynamics of the permanent magnet synchronous motor and the machine-side converter based on the mechanical dynamic function of the speed small signal, and to construct the permanent magnet synchronous motor small signal model and the machine-side converter small signal model based on the analysis results;

[0086] The third building module is used to build an electromagnetic torque small signal model and an electromagnetic torque command value small signal model based on the permanent magnet synchronous motor small signal model and the machine-side converter small signal model;

[0087] The fourth construction module is used to calculate the integral value of the mechanical dynamic function of the speed small signal based on the electromagnetic torque small signal model, introduce the angle difference between the controller coordinate system and the actual coordinate system of the machine-side converter, and construct the conversion relationship between the armature and the current and the coordinate system conversion relationship between the motor terminal voltage;

[0088] The fifth construction module is used to construct an impedance model of the direct-drive wind turbine group considering mechanical dynamics based on the small signal model of the electromagnetic torque command value, the conversion relationship between the armature and the current, and the coordinate system conversion relationship of the motor terminal voltage.

[0089] The beneficial effect of the present invention is that the full-dynamic direct-drive wind turbine impedance modeling method and system provided by the present invention takes into account the influence of mechanical parameters and dynamics on the small signals of the wind turbine when constructing the impedance model. Therefore, the impedance model of the full-dynamic direct-drive wind turbine has better accuracy in the low-frequency band, which helps to more accurately analyze the low-frequency oscillations of the grid-connected system.

[0090] In addition, the invention has a reliable design principle, a simple structure and a very broad application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0092] Figure 1 is a schematic flow chart of a method according to an embodiment of the present invention.

[0093] Figure 2 Conventional control structure diagram of a direct-drive fan.

[0094] Figure 3 This is the impedance flow chart of a conventional direct-drive fan.

[0095] Figure 4 This is a flow chart of impedance synthesis of a direct-drive wind turbine taking into account speed dynamics according to an embodiment of the present invention.

[0096] Figure 5It is a schematic diagram of pitch angle control of a method according to an embodiment of the present invention.

[0097] Figure 6 It is a schematic diagram of electromagnetic torque control of a method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0098] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0099] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0100] The full-dynamic direct-drive wind turbine impedance modeling method provided in the embodiment of the present invention is executed by a computer device, and accordingly, the full-dynamic direct-drive wind turbine impedance modeling system runs in the computer device.

[0101] Figure 1 is a schematic flow chart of a method according to an embodiment of the present invention. Figure 1 The execution subject may be a full dynamic direct drive wind turbine impedance modeling system. According to different requirements, the order of the steps in the flow chart may be changed, and some may be omitted.

[0102] like Figure 1 As shown, the method includes:

[0103] Step 110, constructing a motion equation of a single mass block of a direct-drive wind turbine group by linearizing a small signal of the torque and electromagnetic torque of the wind turbine, and analyzing a mechanical dynamic function of a small speed signal based on the motion equation;

[0104] Step 120, analyzing the speed dynamics of the permanent magnet synchronous motor and the machine-side converter based on the mechanical dynamic function of the speed small signal, and constructing a permanent magnet synchronous motor small signal model and a machine-side converter small signal model based on the analysis results;

[0105] Step 130, constructing an electromagnetic torque small signal model and an electromagnetic torque command value small signal model based on the permanent magnet synchronous motor small signal model and the machine-side converter small signal model;

[0106] Step 140, calculating the integral value of the mechanical dynamic function of the speed small signal based on the electromagnetic torque small signal model, introducing the angle difference between the controller coordinate system and the actual coordinate system of the machine-side converter, and constructing the conversion relationship between the armature and the current and the coordinate system conversion relationship between the motor terminal voltage;

[0107] Step 150 , constructing an impedance model of the direct-drive wind turbine generator system considering mechanical dynamics based on the small signal model of the electromagnetic torque command value, the conversion relationship between the armature and the current, and the coordinate system conversion relationship of the motor terminal voltage.

[0108] To facilitate understanding of the present invention, the full-dynamic direct-drive wind turbine impedance modeling method provided by the present invention is further described below based on the principle of the full-dynamic direct-drive wind turbine impedance modeling method of the present invention and the process of constructing the full-dynamic direct-drive wind turbine impedance model in the embodiment.

[0109] Specifically, the typical control strategies of direct-drive wind power are as follows: Figure 2 As shown in the figure, the grid side converter (GSC) adopts a dual-loop control structure of DC voltage, reactive power outer loop and current inner loop. The DC voltage outer loop can control the DC voltage to be constant, and the reactive power outer loop can control the reactive power at the grid connection point. The machine side converter adopts a torque outer loop, 0d axis current control or maximum torque current ratio control (Maximum Torque Per Ampere control MTPA). To ensure the best efficiency, 0d axis current control is mostly used for hidden pole machines, and MTPA control is mostly used for salient pole machines.

[0110] for Figure 2 The electrical parameters in are explained as follows:

[0111] : Grid resistance, grid inductance.

[0112] : abc three-phase grid voltage, : Grid current, with the current flowing into the grid as the positive direction.

[0113] : Grid-side converter output voltage, :GSC output current, with the positive direction being the current flowing into the grid, due to the parallel relationship .

[0114] : The d-axis component and q-axis component of the GSC output current after Park transformation.

[0115] : The command value.

[0116] : Resistance and inductance of RL filter.

[0117] PLL: Phase Locked Loop abbreviation, : The grid angle tracked by the PLL.

[0118] : DC capacitor voltage, : DC capacitance, : DC voltage command value, : Transfer function of DC voltage outer loop control.

[0119] : Reactive power of GSC grid connection point, : Reactive power command value, : Transfer function of reactive outer loop control.

[0120] : The GSC current inner loop control transfer function can be written as , .

[0121] Represents the three-phase modulated wave signal generated after GSC control. SVPWM: the abbreviation of Space Vector Pulse Width Modulation.

[0122] : The three-phase output voltage of the machine-side converter, : The three-phase output current of the machine-side converter, with the current flowing into the motor as positive.

[0123] is the dq-axis component of the generator-side converter output voltage, It is the dq-axis component of the output current of the machine-side converter.

[0124] : Motor mechanical speed, The motor mechanical rotor angle, The motor electrical rotor angle, Number of motor pole pairs, is the permanent magnet flux of the motor. : Electromagnetic torque command value, : The dq axis current command value of the machine-side converter.

[0125] :MSC current inner loop control transfer function can be written as , .

[0126] Represents the three-phase modulated wave signal generated by the MSC controller.

[0127] The superscript cs represents the dq coordinate system in the controller, and the superscript es represents the actual dq coordinate system. When considering small disturbances, there is an angle difference between the two. A small signal quantity representing a physical quantity.

[0128] Please refer to Figure 3 , the commonly used direct-drive wind turbine impedance modeling methods are as follows:

[0129] (1) Filter modeling

[0130] (1)

[0131] in, , is the grid synchronization angular velocity, is the Laplace operator, It is the small signal quantity of the d-axis component of the grid voltage in the actual dq coordinate system; It is the small signal quantity of the q-axis component of the grid voltage in the actual dq coordinate system; is the small signal quantity of the d-axis component of the grid-side converter voltage in the actual dq coordinate system; is the small signal quantity of the q-axis component of the grid-side converter voltage in the actual dq coordinate system; is the small signal quantity of the d-axis component of the grid-side converter current in the actual dq coordinate system; is the small signal quantity of the q-axis component of the grid-side converter current in the actual dq coordinate system; R g is the resistance of the RL filter, L g is the inductance of the RL filter.

[0132] (2) GSC control modeling

[0133] The governing equation of GSC can be expressed as:

[0134] (2)

[0135] in, is the d component of the grid-side converter voltage in the dq coordinate system of the controller; is the q component of the grid-side converter voltage in the dq coordinate system of the controller; is the DC capacitor voltage, is the command value of the DC capacitor voltage; is the d-axis transfer function of the DC voltage outer loop control; is the q component of the GSC q-axis current in the controller’s dq coordinate system; is the q component of the grid-side converter voltage in the dq coordinate system of the controller; is the reactive power command value; Q is the reactive power of the grid connection point; G gq,outer (s) is the q-axis transfer function of the DC voltage outer loop control; G gq,inner (s) is the q-axis current inner loop control transfer function of the grid-side converter; G gd,inner (s) is the d-axis current inner loop control transfer function of the grid-side converter; is the d component of the grid-side converter current in the dq coordinate system of the controller; is the q component of the grid-side converter current in the dq coordinate system of the controller.

[0136] Taking small signal linearization, we can get:

[0137] (3)

[0138] definition ;

[0139] Then is the matrix that characterizes the dynamics of the GSC current inner loop control.

[0140] Combined with reactive power calculation formula , taking the small signal we get:

[0141] (4)

[0142] in , is the small signal of reactive power, It is the small signal quantity of the d-axis component of the grid-side converter voltage in the dq coordinate system of the controller; It is the small signal quantity of the q-axis component of the grid-side converter voltage in the dq coordinate system of the controller; It is the small signal quantity of the d-axis component of the grid-side converter current in the dq coordinate system of the controller; It is the small signal quantity of the q-axis component of the grid-side converter current in the dq coordinate system of the controller; is the d component of the grid-side converter voltage in the actual dq coordinate system; is the q component of the grid-side converter voltage in the actual dq coordinate system; is the d component of the grid-side converter current in the actual dq coordinate system; is the q component of the grid-side converter current in the actual dq coordinate system.

[0143] The reactive power Q of the grid connection point needs to be calculated using the electrical quantity after the phase-locked loop transformation. Therefore, when considering small disturbances, it is necessary to consider the impact of the phase-locked loop on the electrical quantity of the grid connection point in the control coordinate system:

[0144] (5)

[0145] in , It is the small signal quantity of the d-axis component of the grid voltage in the dq coordinate system of the controller; It is the small signal quantity of the q-axis component of the grid voltage in the dq coordinate system of the controller; is the second-order transfer function of the phase-locked loop.

[0146] Consider the modulation process for GSC:

[0147] (6)

[0148] Define the matrix consisting of steady-state operating points ,in, is the d-axis component of the GSC steady-state output voltage in the actual coordinate system; is the q-axis component of the GSC steady-state output voltage in the actual coordinate system; v dc0 is the steady-state operating point of the DC bus voltage; It is the d-axis component of the GSC controller output voltage (not yet modulated) in the actual coordinate system.

[0149] (3) Phase-locked loop modeling

[0150] The GSC current small signal can be expressed in the control coordinate system as:

[0151] (7)

[0152] The voltage small signal can be expressed as:

[0153] (8)

[0154] in: ;

[0155] is the second-order transfer function of the phase-locked loop:

[0156] (9)

[0157] Among them, k p,pll k is the proportional coefficient of the phase-locked loop PI controller; i,pll is the integral coefficient of the phase-locked loop PI controller.

[0158] (4) DC capacitor modeling

[0159] The DC capacitor connecting GSC and MSC is analyzed by small signal. The DC bus power balance equation can be expressed as:

[0160] (10)

[0161] C dc is the DC capacitance; v g,d is the d component of the grid-side converter output voltage, v g,q is the qd component of the grid-side converter output voltage, v m,d is the d component of the output voltage of the machine-side converter, v m,q is the qd component of the output voltage of the machine-side converter, i g,d is the d component of the grid-side converter output current, i g,q is the qd component of the grid-side converter output current, i m,d is the d component of the output current of the machine-side converter, i m,q is the qd component of the machine-side converter output current.

[0162] Linearizing (9) yields:

[0163] (11)

[0164] in, is the small signal value of the DC capacitor voltage; is the small signal quantity of the d-axis component of the grid-side converter voltage in the actual dq coordinate system; is the small signal quantity of the q-axis component of the grid-side converter voltage in the actual dq coordinate system; is the small signal quantity of the d-axis component of the grid-side converter current in the actual dq coordinate system; is the small signal quantity of the q-axis component of the grid-side converter current in the actual dq coordinate system; is the small signal quantity of the d-axis component of the generator-side converter voltage in the actual dq coordinate system; is the small signal quantity of the q-axis component of the generator-side converter voltage in the actual dq coordinate system; is the small signal quantity of the d-axis component of the machine-side converter current in the actual dq coordinate system; It is the small signal quantity of the q-axis component of the machine-side converter current in the actual dq coordinate system;

[0165] The impedance components are:

[0166] (12)

[0167] (13)

[0168] in, is the DC capacitor voltage, is the DC capacitance, is the DC capacitor voltage; is the d-axis component of the grid-side converter voltage in the actual dq coordinate system; is the q-axis component of the grid-side converter voltage in the actual dq coordinate system; is the d-axis component of the grid-side converter current in the actual dq coordinate system; is the q-axis component of the grid-side converter current in the actual dq coordinate system; is the d-axis component of the machine-side converter voltage in the actual dq coordinate system; is the q-axis component of the machine-side converter voltage in the actual dq coordinate system; is the d-axis component of the machine-side converter current in the actual dq coordinate system; is the q-axis component of the machine-side converter current in the actual dq coordinate system;

[0169] (5) Synchronous motor modeling

[0170] The permanent magnet synchronous motor relies on built-in permanent magnets to provide excitation. In the dq synchronous rotating coordinate system with rotor flux orientation, the mathematical model of the permanent magnet synchronous motor can be expressed as:

[0171] (14)

[0172] Among them, R s is the stator armature resistance of the permanent magnet synchronous motor; L d is the d-axis component of the motor stator inductance; L q is the q-axis component of the motor stator inductance;

[0173] Linearization yields:

[0174] (15)

[0175] definition .

[0176] (6) MSC modeling

[0177] The MSC inner loop uses current control:

[0178] (16)

[0179] in, is the command value of the d component of the current of the machine-side converter in the dq coordinate system of the controller; is the d component of the current of the machine-side converter in the dq coordinate system of the controller; is the command value of the q component of the current of the machine-side converter in the dq coordinate system of the controller; is the q component of the current of the machine-side converter in the dq coordinate system of the controller; is the d-axis current inner loop control transfer function of the machine-side converter; is the q-axis current inner loop control transfer function of the machine-side converter; is the d component of the voltage of the machine-side converter in the dq coordinate system of the controller; is the q component of the voltage of the machine-side converter in the dq coordinate system of the controller; is the electrical speed of the motor;

[0180] In MSC control, the angle used by Park is the electrical angle of the motor rotor. In the commonly used impedance model, the control coordinate system is considered to be the same as the actual coordinate system, that is, the coordinate systems represented by the superscripts cs and es remain coincident. Taking small signal linearization, we can get

[0181] (17)

[0182] in, is the motor electrical speed;

[0183] Define the matrix that characterizes the dynamics of the MSC current inner loop control:

[0184] (18)

[0185] MSC mostly uses direct debugging, and the control signal output by the controller needs to be divided by half of the DC voltage first. , and then multiply it by half of the preset rated DC voltage as the modulation factor, that is, This process can be expressed as

[0186] (19)

[0187] in, is the d-axis component of the voltage of the three-phase modulation signal in the actual dq coordinate system, It is the q-axis component of the voltage of the three-phase modulated signal in the actual dq coordinate system.

[0188] Taking small signal linearization of the above equation and substituting (17) into it, we can obtain:

[0189] (20)

[0190] in:

[0191] (twenty one)

[0192] in, is the q-axis component of the motor stator steady-state voltage;

[0193] Substituting (14) and (19) into (10) and eliminating the motor side variables, we can obtain:

[0194] (twenty two)

[0195] Where:

[0196] (twenty three)

[0197] By deriving equation (21), the generator-side dynamics have been reflected as an impact on the DC voltage.

[0198] Combining equation (22) with the GSC side formula, we can get the impedance model of the currently commonly used direct-drive wind turbine:

[0199] (twenty four)

[0200] in:

[0201] (25)

[0202] In the formula .

[0203] Please refer to Figure 4 In one embodiment of the present invention, the constructed full-dynamic direct-drive wind turbine impedance model includes:

[0204] Wind turbine torque It can be expressed as:

[0205] (26)

[0206] In the formula, is the air density, is the motor mechanical speed, is the blade length, is the wind speed, is the pitch angle, is the torque coefficient, is the tip speed ratio and .

[0207] Assuming the wind speed is constant, the small signal linearization of (26) yields:

[0208] (27)

[0209] It shows that the mechanical torque dynamics depends on the speed dynamics and the pitch angle control dynamics.

[0210] Figure 5 The pitch angle control block diagram is shown, and the small signal linearization can be obtained:

[0211] (28)

[0212] Among them, G pa1 (s) is the transfer function of the PI controller in the pitch control system, G pa2 (s) is the wind turbine pitch angle control transfer function, s is the complex frequency domain Laplace operator;

[0213] Figure 6 The electromagnetic torque control block diagram is shown, and the small signal linearization can be obtained:

[0214] (29)

[0215] Among them, G wm (s) is the wind turbine torque control transfer function;

[0216] A major advantage of direct-drive wind turbines over doubly-fed wind turbines is that they do not require a gearbox and have low mechanical complexity. Therefore, a single mass module is used here to characterize the shaft system of a direct-drive wind turbine. The motion equation of a single mass block can be expressed as

[0217] (30)

[0218] Where J is the moment of inertia, is the friction damping torque, and , is the electrical speed, D m is the damping coefficient.

[0219] Linearizing (30) yields

[0220] (31)

[0221] Where p is the number of motor pole pairs.

[0222] Defining the Mechanical Time Constant , and the Pull transformation of (31) yields:

[0223] (32)

[0224] make , substituting (28) into (32) we get:

[0225] (33)

[0226] The above analyzes the relationship between speed dynamics and electromagnetic torque and electromagnetic torque command value.

[0227] Next, the speed dynamics will be analyzed and modeled in the motor and MSC control.

[0228] (1) Permanent magnet synchronous motor modeling

[0229] Taking a small signal for the motor equation and taking a small signal for the speed

[0230] (34)

[0231] in, is the small signal quantity of the d-axis component of the voltage of the generator-side converter in the actual dq coordinate system; is the small signal quantity of the q-axis component of the voltage of the generator-side converter in the actual dq coordinate system; is the small signal quantity of the d-axis component of the current of the machine-side converter in the actual dq coordinate system; is the small signal quantity of the q-axis component of the current of the machine-side converter in the actual dq coordinate system; is the q-axis component of the inductance, is the d-axis component of the inductance; is the permanent magnet flux of the motor;

[0232] definition ;

[0233] In the above formula , is the vector representation of the small speed signal.

[0234] (2) MSC control modeling

[0235] The control equation of MSC is linearized by small signal:

[0236] (35)

[0237] in, It is the small signal quantity of the d-axis component of the voltage of the machine-side converter in the dq coordinate system of the controller; It is the small signal quantity of the q-axis component of the voltage of the machine-side converter in the controller dq coordinate system; It is the small signal quantity of the d-axis component of the current of the machine-side converter in the controller dq coordinate system; is the small signal quantity of the q-axis component of the current of the machine-side converter in the controller dq coordinate system; G md,inner is the d-axis current control transfer function of the inner loop of the generator-side converter, G mq,inner is the q-axis current control transfer function of the inner loop of the machine-side converter; is the small signal quantity of the d-axis component of the current command value of the machine-side converter in the controller dq coordinate system; is the small signal quantity of the q-axis component of the current command value of the machine-side converter in the controller dq coordinate system;

[0238] definition .

[0239] (3) Motor electromagnetic torque modeling

[0240] The above analysis shows the relationship between the speed small signal and the electromagnetic torque small signal. The electromagnetic torque of the motor will be modeled as follows:

[0241] The torque equation of permanent magnet synchronous motor can be expressed as:

[0242] (36)

[0243] Among them, i mq is the q-axis component of the current of the machine-side converter, i md is the d-axis component of the current of the machine-side converter;

[0244] Taking the small signal, we can get:

[0245] (37)

[0246] Writing this in matrix form:

[0247] (38)

[0248] In the above formula .

[0249] (4) Electromagnetic torque command value modeling

[0250] The small speed signal will affect the electromagnetic torque command value, which will further affect the current command value. In actual control, there are MTPA and 0d-axis current control from the electromagnetic torque command value to the current command value.

[0251] When MTPA control is used, the small signal from the electromagnetic torque to the current command value can be:

[0252] (39)

[0253] Where p represents the number of motor pole pairs;

[0254] When 0d-axis current control is used:

[0255] (40)

[0256] (5) The impact of speed dynamics on MSC Park transformation:

[0257] The above analysis shows ;

[0258] Integrating it yields:

[0259] (41)

[0260] MSC Utilization To perform Park transformation, when considering small speed disturbances, there is an angle difference between the MSC control coordinate system and the actual coordinate system. Considering the angle difference between the control coordinate system cs and the actual coordinate system es, the conversion relationship between the motor armature current can be expressed as:

[0261] (42)

[0262] (43)

[0263] Where E is the two-dimensional unit matrix ;

[0264] The conversion relationship between the motor terminal voltage and the two coordinate systems can be expressed as:

[0265] (44)

[0266] (45)

[0267] When the permanent magnet synchronous motor is a hidden pole machine, , Can be simplified accordingly, then:

[0268] (46)

[0269] (47)

[0270] In summary, the impedance model of the direct-drive wind turbine considering the speed dynamics and pitch angle dynamics can be obtained.

[0271] According to the impedance synthesis flow chart, the impedance model of the direct-drive wind turbine considering the speed dynamics and pitch angle dynamics can be obtained:

[0272] (48)

[0274] (49)

[0275] In this embodiment, the full-dynamic direct-drive wind turbine impedance modeling system can be divided into multiple functional modules according to the functions it performs. The module referred to in the present invention refers to a series of computer program segments that can be executed by at least one processor and can complete fixed functions, which are stored in a memory. In this embodiment, the functions of each module will be described in detail in subsequent embodiments.

[0276] The first construction module is used to construct the motion equation of the single mass block of the direct-drive wind turbine group by linearizing the small signal of the torque and electromagnetic torque of the wind turbine, and analyze the mechanical dynamic function of the small speed signal based on the motion equation and the pre-constructed grid-side converter model;

[0277] The second construction module is used to analyze the speed dynamics of the permanent magnet synchronous motor and the machine-side converter based on the mechanical dynamic function of the speed small signal, and to construct the permanent magnet synchronous motor small signal model and the machine-side converter small signal model based on the analysis results;

[0278] The third building module is used to build an electromagnetic torque small signal model and an electromagnetic torque command value small signal model based on the permanent magnet synchronous motor small signal model and the machine-side converter small signal model;

[0279] The fourth construction module is used to calculate the integral value of the mechanical dynamic function of the speed small signal based on the electromagnetic torque small signal model, introduce the angle difference between the controller coordinate system and the actual coordinate system, and construct the conversion relationship between the armature and the current and the coordinate system conversion relationship between the motor terminal voltage;

[0280] The fifth construction module is used to construct an impedance model of the direct-drive wind turbine group considering mechanical dynamics based on the small signal model of the electromagnetic torque command value, the conversion relationship between the armature and the current, and the coordinate system conversion relationship of the motor terminal voltage.

[0281] Optionally, as an embodiment of the present invention, the first building module includes:

[0282] The torque of the wind turbine It is expressed as:

[0283] ;

[0284] In the formula, is the air density, is the blade length, is the wind speed, is the pitch angle, is the tip speed ratio and , C T is the torque coefficient;

[0285] If the wind speed remains unchanged, the torque of the wind turbine is linearized by a small signal, and the result is:

[0286] ;

[0287] in, A small signal quantity representing a physical quantity, is the mechanical speed of the wind turbine;

[0288] The small signal of the pitch angle is:

[0289] ;

[0290] Among them, G pa1 (s) is the transfer function of the PI controller in the pitch control system, G pa2(s) is the wind turbine pitch angle control transfer function, s is the complex frequency domain Laplace operator;

[0291] Small signal linearization of electromagnetic torque:

[0292] ;

[0293] Among them, G wm (s) is the wind turbine torque control transfer function;

[0294] The single mass module is used to characterize the shaft system of the direct-drive wind turbine. The motion equation of the single mass block is:

[0295] ;

[0296] Where J is the moment of inertia, is the friction damping torque, and , is the electrical speed, D m is the damping coefficient;

[0297] Linearize the single mass fast equation of the direct-drive wind turbine and substitute the wind turbine torque small signal equation into it to obtain:

[0298] ;

[0299] Define the mechanical time constant:

[0300] ;

[0301] Where, p is the number of motor pole pairs;

[0302] Substituting the small signal of the pitch angle into the single mass fast model equation, we get:

[0303] ;

[0304] make , and obtain the mechanical dynamic function of the small speed signal:

[0305] .

[0306] Optionally, as an embodiment of the present invention, the second building module includes:

[0307] Based on the small signal of the motor equation, the small signal of the speed is taken to obtain the small signal model of the permanent magnet synchronous motor:

[0308] ;

[0309] in, is the small signal quantity of the d-axis component of the output voltage of the machine-side converter in the actual dq coordinate system; is the small signal quantity of the q-axis component of the output voltage of the machine-side converter in the actual dq coordinate system; is the small signal quantity of the d-axis component of the output current of the machine-side converter in the actual dq coordinate system; is the small signal quantity of the q-axis component of the output current of the machine-side converter in the actual dq coordinate system; is the q-axis component of the inductance, is the d-axis component of the inductance; is the permanent magnet flux of the motor;

[0310] definition ;

[0311] , is the vector representation of the small speed signal;

[0312] The control equation of the machine-side converter is linearized by small signal:

[0313] ;

[0314] in, It is the small signal quantity of the d-axis component of the voltage of the machine-side converter in the dq coordinate system of the controller; It is the small signal quantity of the q-axis component of the voltage of the machine-side converter in the controller dq coordinate system; It is the small signal quantity of the d-axis component of the current of the machine-side converter in the controller dq coordinate system; is the small signal quantity of the q-axis component of the current of the machine-side converter in the controller dq coordinate system; G md,inner is the d-axis current control transfer function of the inner loop of the generator-side converter, G mq,inner is the q-axis current control transfer function of the inner loop of the machine-side converter; is the small signal value of the d-axis current command value of the machine-side converter in the controller dq coordinate system; is the small signal value of the q-axis current command value of the machine-side converter in the controller dq coordinate system;

[0315] definition , .

[0316] Optionally, as an embodiment of the present invention, the third building block includes:

[0317] The torque equation of a permanent magnet synchronous motor is:

[0318] ;

[0319] Among them, i mq is the q-axis component of the current of the machine-side converter, i md is the d-axis component of the current of the machine-side converter;

[0320] Taking a small signal of the torque equation, we get the electromagnetic torque small signal model:

[0321] ;

[0322] Convert the electromagnetic torque small signal model into a matrix:

[0323] ;

[0324] ;

[0325] Construct a small signal model of electromagnetic torque command value:

[0326] If the maximum torque current ratio control is adopted, the conversion function from the electromagnetic torque small signal to the current command value small signal is:

[0327] ;

[0328] Where p represents the number of motor pole pairs;

[0329] If 0d-axis current control is adopted, the conversion function from the electromagnetic torque small signal to the current command value small signal is:

[0330] .

[0331] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A fully dynamic direct-drive wind turbine impedance modeling method, characterized in that: include: By linearizing the torque and electromagnetic torque of the wind turbine in small signals, the motion equation of the single mass block of the direct-drive wind turbine is constructed, and the mechanical dynamic function of the small speed signal is analyzed based on the motion equation; Based on the mechanical dynamic function of the speed small signal, the speed dynamics of the permanent magnet synchronous motor and the machine-side converter are analyzed, and the permanent magnet synchronous motor small signal model and the machine-side converter small signal model are constructed based on the analysis results; Based on the permanent magnet synchronous motor small signal model and the machine-side converter small signal model, an electromagnetic torque small signal model and an electromagnetic torque command value small signal model are constructed; Based on the electromagnetic torque small signal model, the integral value of the mechanical dynamic function of the speed small signal is calculated, the angle difference between the controller coordinate system and the actual coordinate system of the machine-side converter is introduced, and the conversion relationship between the armature and the current and the coordinate system conversion relationship between the motor terminal voltage are constructed; An impedance model of a direct-drive wind turbine considering mechanical dynamics is constructed based on the small signal model of the electromagnetic torque command value, the conversion relationship between the armature and the current, and the coordinate system conversion relationship of the motor terminal voltage.

2. The method according to claim 1, characterized in that: By linearizing the small signals of the torque and electromagnetic torque of the wind turbine, the motion equation of the single mass block of the direct-drive wind turbine is constructed, and the mechanical dynamic function of the small speed signal is analyzed based on the motion equation, including: The torque of the wind turbine It is expressed as: ； In the formula, is the air density, is the blade length, is the wind speed, is the pitch angle, is the tip speed ratio and , C T is the torque coefficient; If the wind speed remains unchanged, the torque of the wind turbine is linearized by a small signal, and the result is: ； in, A small signal quantity representing a physical quantity, is the mechanical speed of the wind turbine; The small signal of the pitch angle is: ； Among them, G pa1 (s) is the transfer function of the PI controller in the pitch control system, G pa2 (s) is the wind turbine pitch angle control transfer function, s is the complex frequency domain Laplace operator; Small signal linearization of electromagnetic torque: ； Among them, G wm (s) is the wind turbine torque control transfer function; The single mass module is used to characterize the shaft system of the direct-drive wind turbine. The motion equation of the single mass block is: ； Where J is the moment of inertia, is the friction damping torque, and , is the electrical speed, D m is the damping coefficient; Linearize the single mass fast equation of the direct-drive wind turbine and substitute the wind turbine torque small signal equation into it to obtain: ； Define the mechanical time constant: ； Where p is the number of motor pole pairs; Substituting the small signal of the pitch angle into the single mass fast model equation, we get: ； make , and obtain the mechanical dynamic function of the small speed signal: 。 3. The method according to claim 2, characterized in that Based on the mechanical dynamic function of the speed small signal, the speed dynamics of the permanent magnet synchronous motor and the machine-side converter are analyzed, and the permanent magnet synchronous motor small signal model and the machine-side converter small signal model are constructed based on the analysis results, including: Based on the small signal of the motor equation, the small signal of the speed is taken to obtain the small signal model of the permanent magnet synchronous motor: ； Among them, the definition , is the small signal quantity of the d-axis component of the output voltage of the machine-side converter in the actual dq coordinate system; is the small signal quantity of the q-axis component of the output voltage of the machine-side converter in the actual dq coordinate system; is the small signal quantity of the d-axis component of the output current of the machine-side converter in the actual dq coordinate system; is the small signal quantity of the q-axis component of the output current of the machine-side converter in the actual dq coordinate system; is the q-axis component of the inductance, is the d-axis component of the inductance; is the permanent magnet flux of the motor; is the d-axis component of the machine-side converter current in the actual dq coordinate system; is the q-axis component of the machine-side converter current in the actual dq coordinate system; definition ; , is the vector representation of the small speed signal; The control equation of the machine-side converter is linearized by small signal: ； in, It is the small signal quantity of the d-axis component of the voltage of the machine-side converter in the dq coordinate system of the controller; It is the small signal quantity of the q-axis component of the voltage of the machine-side converter in the controller dq coordinate system; It is the small signal quantity of the d-axis component of the current of the machine-side converter in the controller dq coordinate system; is the small signal quantity of the q-axis component of the current of the machine-side converter in the controller dq coordinate system; G md,inner is the d-axis current control transfer function of the inner loop of the generator-side converter, G mq,inner is the q-axis current control transfer function of the inner loop of the machine-side converter; is the small signal value of the d-axis current command value of the machine-side converter in the controller dq coordinate system; is the small signal value of the q-axis current command value of the machine-side converter in the controller dq coordinate system; definition 。 4. The method according to claim 3, characterized in that Based on the permanent magnet synchronous motor small signal model and the machine-side converter small signal model, an electromagnetic torque small signal model and an electromagnetic torque command value small signal model are constructed, including: The torque equation of a permanent magnet synchronous motor is: ； Among them, i mq is the q-axis component of the current of the machine-side converter, i md is the d-axis component of the current of the machine-side converter; Taking a small signal of the torque equation, we get the electromagnetic torque small signal model: ； Convert the electromagnetic torque small signal model into a matrix: ； ； Construct a small signal model of electromagnetic torque command value: If the maximum torque current ratio control is adopted, the conversion function from the electromagnetic torque small signal to the current command value small signal is: ； Where p represents the number of motor pole pairs; If 0d-axis current control is adopted, the conversion function from the electromagnetic torque small signal to the current command value small signal is: 。 5. The method according to claim 4, characterized in that Based on the electromagnetic torque small signal model, the integral value of the mechanical dynamic function of the speed small signal is obtained, the angle difference between the controller coordinate system and the actual coordinate system of the machine-side converter is introduced, and the conversion relationship between the armature and the current and the coordinate system conversion relationship of the motor terminal voltage are constructed, including: Integrate the mechanical dynamic function of the speed small signal to obtain the small signal value of the electrical rotor angle: ； Substitute the electromagnetic torque small signal model into the mechanical dynamic function of the speed small signal; Considering the angle difference between the machine-side converter control coordinate system cs and the actual coordinate system es, the conversion relationship of the motor armature current is: ； ； Where E is a two-dimensional unit matrix; The conversion relationship between the motor terminal voltage in the controller's dq coordinate system and the actual dq coordinate system is: ； ； If the permanent magnet synchronous motor is a hidden pole machine, then : ； 。 6. The method according to claim 5, characterized in that Based on the small signal model of electromagnetic torque command value, the conversion relationship between armature and current, and the coordinate system conversion relationship of motor terminal voltage, an impedance model of direct-drive wind turbine considering mechanical dynamics is constructed, including: Construct an impedance model of a direct-drive wind turbine considering mechanical dynamics: ； ； in, ； ； 。 7. A full-dynamic direct-drive wind turbine impedance modeling system, characterized in that: include: The first construction module is used to construct the motion equation of the single mass block of the direct-drive wind turbine group by linearizing the small signal of the torque and electromagnetic torque of the wind turbine, and analyze the mechanical dynamic function of the small signal of the speed based on the motion equation; The second construction module is used to analyze the speed dynamics of the permanent magnet synchronous motor and the machine-side converter based on the mechanical dynamic function of the speed small signal, and to construct the permanent magnet synchronous motor small signal model and the machine-side converter small signal model based on the analysis results; The third building module is used to build an electromagnetic torque small signal model and an electromagnetic torque command value small signal model based on the permanent magnet synchronous motor small signal model and the machine-side converter small signal model; The fourth construction module is used to calculate the integral value of the mechanical dynamic function of the speed small signal based on the electromagnetic torque small signal model, introduce the angle difference between the controller coordinate system and the actual coordinate system of the machine-side converter, and construct the conversion relationship between the armature and the current and the coordinate system conversion relationship between the motor terminal voltage; The fifth construction module is used to construct an impedance model of the direct-drive wind turbine group considering mechanical dynamics based on the small signal model of the electromagnetic torque command value, the conversion relationship between the armature and the current, and the coordinate system conversion relationship of the motor terminal voltage.

8. The system according to claim 7, characterized in that The first building block comprises: The torque of the wind turbine It is expressed as: ； In the formula, is the air density, is the blade length, is the wind speed, is the pitch angle, is the tip speed ratio and , C T is the torque coefficient; If the wind speed remains unchanged, the torque of the wind turbine is linearized by a small signal, and the result is: ； in, A small signal quantity representing a physical quantity, is the mechanical speed of the wind turbine; The small signal of the pitch angle is: ； Among them, G pa1 (s) is the transfer function of the PI controller in the pitch control system, G pa2 (s) is the wind turbine pitch angle control transfer function, s is the complex frequency domain Laplace operator; Small signal linearization of electromagnetic torque: ； Among them, G wm (s) is the wind turbine torque control transfer function; The single mass module is used to characterize the shaft system of the direct-drive wind turbine. The motion equation of the single mass block is: ； Where J is the moment of inertia, is the friction damping torque, and , is the electrical speed, D m is the damping coefficient; Linearize the single mass fast equation of the direct-drive wind turbine and substitute the wind turbine torque small signal equation into it to obtain: ； Define the mechanical time constant: ； Where p is the number of motor pole pairs; Substituting the small signal of the pitch angle into the single mass fast model equation, we get: ； make , and obtain the mechanical dynamic function of the small speed signal: 。 9. The system according to claim 8, characterized in that The second building block comprises: Based on the small signal of the motor equation, the small signal of the speed is taken to obtain the small signal model of the permanent magnet synchronous motor: ； Among them, the definition , is the small signal quantity of the d-axis component of the output voltage of the machine-side converter in the actual dq coordinate system; is the small signal quantity of the q-axis component of the output voltage of the machine-side converter in the actual dq coordinate system; is the small signal quantity of the d-axis component of the output current of the machine-side converter in the actual dq coordinate system; is the small signal quantity of the q-axis component of the output current of the machine-side converter in the actual dq coordinate system; is the q-axis component of the inductance, is the d-axis component of the inductance; is the permanent magnet flux of the motor; is the d-axis component of the machine-side converter current in the actual dq coordinate system; is the q-axis component of the machine-side converter current in the actual dq coordinate system; definition ; , is the vector representation of the small speed signal; The control equation of the machine-side converter is linearized by small signal: ； in, It is the small signal quantity of the d-axis component of the voltage of the machine-side converter in the dq coordinate system of the controller; It is the small signal quantity of the q-axis component of the voltage of the machine-side converter in the controller dq coordinate system; It is the small signal quantity of the d-axis component of the current of the machine-side converter in the controller dq coordinate system; is the small signal quantity of the q-axis component of the current of the machine-side converter in the controller dq coordinate system; G md,inner is the d-axis current control transfer function of the inner loop of the generator-side converter, G mq,inner is the q-axis current control transfer function of the inner loop of the machine-side converter; is the small signal value of the d-axis current command value of the machine-side converter in the controller dq coordinate system; is the small signal value of the q-axis current command value of the machine-side converter in the controller dq coordinate system; definition .

10. The system according to claim 9, characterized in that The third building block comprises: The torque equation of a permanent magnet synchronous motor is: ； Among them, i mq is the q-axis component of the current of the machine-side converter, i md is the d-axis component of the current of the machine-side converter; Taking a small signal of the torque equation, we get the electromagnetic torque small signal model: ； Convert the electromagnetic torque small signal model into a matrix: ； ； Construct a small signal model of electromagnetic torque command value: If the maximum torque current ratio control is adopted, the conversion function from the electromagnetic torque small signal to the current command value small signal is: ； Where p represents the number of motor pole pairs; If 0d-axis current control is adopted, the conversion function from the electromagnetic torque small signal to the current command value small signal is: 。

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