Method and system for suppressing subsynchronous oscillation of voltage source wind turbine generator

Abstract

The invention discloses a method and system for suppressing subsynchronous oscillation of a voltage source wind turbine generator, and the method comprises the steps: collecting stator three-phase voltage and stator three-phase current of a doubly-fed generator, and obtaining d-axis and q-axis stator voltage DC components and stator current DC components; obtaining a rotor direct current component; obtaining stator output active power, stator output reactive power, and active power and reactive power after passing through a low-pass filter, and obtaining a compensation instruction of adaptive virtual damping control; outputting a d-axis rotor current instruction and a q-axis rotor current instruction, and obtaining a rotor voltage instruction under the synchronous rotating coordinate system; superposing the rotor voltage instruction and a compensation instruction of adaptive virtual damping control to obtain a new rotor voltage instruction; and after the new rotor voltage instruction and the rotor voltage instruction are modulated by an SVPWM link, a rotor side converter switching tube control signal is generated, so that subsynchronous oscillation suppression of the doubly-fed wind power generation system is realized.

Description

Technical Field

[0001] The present invention relates to the field of new energy access and control technology, and more specifically, to a method and system for suppressing subsynchronous oscillation of a voltage source wind turbine generator set. Background Art

[0002] As my country's energy structure continues to optimize, the proportion of new energy sources is gradually increasing. Among them, the penetration rate of wind power generation is constantly improving, the installed capacity of doubly-fed induction generators (DFIG) is increasing, and the access of a large number of power electronic equipment has gradually made the power grid present weak grid characteristics. At the same time, the long-distance transmission of wind power will lead to increased line losses. Therefore, compensation capacitors are usually connected in series in the line to improve the power transmission capacity of the line. The interaction between series compensation capacitors and doubly-fed wind turbines may cause serious sub-synchronous oscillation (SSO) accidents, affecting the stability of the system. Moreover, in weak power grids, for doubly-fed wind power generation, problems such as wind speed changes and diverse wind turbine capacities are obvious. This unstable factor will cause the wind power system to have variable and diverse oscillations when sub-synchronous oscillations occur.

[0003] The existing solution to the subsynchronous oscillation problem of voltage source doubly-fed wind turbines connected to a weak grid is to use additional damping control, which introduces additional damping links to improve system damping and enhance system stability by changing the control mode of the DFIG machine-side converter or the grid-side converter. However, traditional additional damping control generally extracts a specific oscillation frequency range through a bandpass filter, and its control parameters are fixed and dependent on the controller hardware. Therefore, it lacks adaptability to the variable subsynchronous oscillation of the doubly-fed wind power generation system. When suppressing subsynchronous oscillation, it is necessary to consider the variable characteristics of the subsynchronous oscillation of the doubly-fed wind power generation system.

[0004] Therefore, the suppression of subsynchronous oscillations of voltage source doubly-fed wind power generation systems under weak power grids is still a core difficulty and requires further research and breakthroughs. Summary of the invention

[0005] The technical solution of the present invention provides a method and system for suppressing subsynchronous oscillation of a voltage source wind turbine set, so as to solve the problem of how to suppress subsynchronous oscillation of a doubly-fed wind power generation system under a weak power grid.

[0006] In order to solve the above problem, the present invention provides a method for suppressing subsynchronous oscillation of a voltage source wind turbine generator set, the method comprising:

[0007] Collect the stator three-phase voltage U of the double-fed generator sa , U sb , Usc and the stator three-phase current i sa 、i sb 、i sc , by the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc Transform to obtain the stator three-phase voltage U sa , U sb , U sc The DC component U of the d-axis and q-axis stator voltage in the synchronous rotating coordinate system sd , U sq And the stator three-phase current i sa 、i sb 、i sc The DC components i of the d-axis and q-axis stator currents in the synchronous rotating coordinate system sd 、i sq ;

[0008] Collect the three-phase rotor current i of the doubly fed generator ra 、i rb 、i ra and the rotor electrical angular velocity θ r , by the three-phase rotor current i ra 、i rb 、i rc and the rotor electrical angular velocity θ r Transform to obtain the three-phase rotor current i ra 、i rb 、i rc The d-axis and q-axis rotor DC components i in the synchronous rotating coordinate system rd 、i rq ;

[0009] Based on the stator voltage DC component U sd , U sq And the stator current DC component i sd 、i sq Obtain the stator output active power P′ and the stator output reactive power Q′;

[0010] Based on the stator output active power P′ and the stator output reactive power Q′, the active power P after passing through the low-pass filter and the reactive power Q after passing through the low-pass filter are obtained;

[0011] Calculate the adaptive compensation frequency ω com , based on the adaptive compensation frequency ω com Get the compensation command Δu of adaptive virtual damping controlrd_ref ;

[0012] Calculate the d-axis stator voltage command U in the synchronous rotating coordinate system ref and the d-axis stator voltage DC component U sd The deviation of the q-axis stator voltage command zero value and the q-axis stator voltage DC component U sq The deviation is input into the PI regulator of the stator voltage outer loop for processing, and the d-axis and q-axis rotor current instructions i are output. rd_ref 、i rq_ref ;

[0013] Calculate the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system rd_ref and the rotor DC component i rd The deviation between the rotor current command i rq_ref and the rotor DC component i rq The deviation between them is input into the PI regulator of the rotor current inner loop to obtain the rotor voltage command u in the synchronous rotating coordinate system. rd_ref 、u rq_ref ;

[0014] The rotor voltage command u rd_ref The compensation command △u of the adaptive virtual damping control rd_ref After superposition, the new rotor voltage command u is obtained rd_ref1 ;

[0015] The new rotor voltage command u of the d-axis and q-axis rd_ref1 , rotor voltage command u rq_ref After modulation by the SVPWM link, the rotor-side converter switch control signal is generated, thereby achieving subsynchronous oscillation suppression of the doubly-fed wind power generation system.

[0016] Preferably, the stator three-phase voltage U of the doubly-fed generator is collected sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc , through the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc Transform to obtain the stator three-phase voltage U sa , U sb , U sc The DC component U of the d-axis and q-axis stator voltage in the synchronous rotating coordinate system sd , U sqAnd the stator three-phase current i sa 、i sb 、i sc The DC components i of the d-axis and q-axis stator currents in the synchronous rotating coordinate system sd 、i sq ,include:

[0017]

[0018] Among them, θ is the orientation angle of coordinate transformation, x A 、x B 、x C represents the three-phase stator voltage of the doubly-fed generator in the three-phase stationary coordinate system, x d 、x q Represents the d-axis and q-axis DC components of the stator voltage / current in the synchronous rotating coordinate system.

[0019] Preferably, the three-phase rotor current i of the doubly-fed generator is collected ra 、i rb 、i rc and the rotor electrical angular velocity θ r , by the three-phase rotor current i ra 、i rb 、i rc and the rotor electrical angular velocity θ r Transform to obtain the three-phase rotor current i ra 、i rb 、i rc The d-axis and q-axis rotor DC components i in the synchronous rotating coordinate system rd 、i rq ,include:

[0020]

[0021] Among them, θ r It is the electrical angular velocity of the doubly-fed generator rotor measured by the speed measuring device.

[0022] Preferably, the stator voltage DC component U sd , U sq And the stator current DC component i sd 、i sq Obtaining the stator output active power P' and stator output reactive power Q' includes:

[0023]

[0025] Preferably, the obtaining of the active power P after passing through a low-pass filter and the reactive power Q after passing through a low-pass filter based on the stator output active power P′ and the stator output reactive power Q′ comprises:

[0026]

[0027] Among them, ω f represents the cutoff frequency of the low-pass filter, and s represents the Laplace operator.

[0028] Preferably, the calculation of the adaptive compensation frequency ω com , based on the adaptive compensation frequency ω com Get the compensation command △u of adaptive virtual damping control rd_ref ,include:

[0029] The collected single-phase grid-connected current is transformed by Fourier transform and the subsynchronous oscillation frequency f is obtained by the bubble method. c , using formula (39) to obtain the adaptive compensation frequency ω com , adaptive compensation frequency ω com Able to actively modulate its own parameters to suppress subsynchronous oscillations according to oscillation frequency and grid changes:

[0030] ω com =2*pi*(50-f c ) (19)

[0031] pi is the circumference of a circle, π.

[0032] Damping compensation is performed in the d-axis rotor current loop, and the compensation command Δu of the adaptive virtual damping control is obtained using equation (40): rd_ref :

[0033]

[0034] Among them, K com is the compensation coefficient of adaptive virtual damping.

[0035] Preferably, the calculation of the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system rd_ref and the rotor DC component i rd The deviation between the rotor current command i rq_ref and the rotor DC component i rq The deviation between them is input into the PI regulator of the rotor current inner loop to obtain the rotor voltage command u in the synchronous rotating coordinate system. rd_ref 、u rq_ref ,include:

[0036]

[0037] Among them, K p2 and K i2 They are the proportional coefficient and integral coefficient of the PI regulator in the rotor current loop respectively.

[0038] Based on another aspect of the present invention, the present invention provides a system for suppressing subsynchronous oscillation of a voltage source wind turbine generator set, the system comprising:

[0039] The acquisition unit is used to collect the stator three-phase voltage U of the double-fed generator. sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc , through the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc Transform to obtain the stator three-phase voltage U sa , U sb , U sc The DC component U of the d-axis and q-axis stator voltage in the synchronous rotating coordinate system sd , U sq And the stator three-phase current i sa 、i sb 、i sc The DC components i of the d-axis and q-axis stator currents in the synchronous rotating coordinate system sd 、i sq ; Collect the three-phase rotor current i of the doubly fed generator ra 、i rb 、i rc and the rotor electrical angular velocity θ r , by the three-phase rotor current i ra 、i rb 、i rc and the rotor electrical angular velocity θ r Transform to obtain the three-phase rotor current i ra 、i rb 、i rc The d-axis and q-axis rotor DC components i in the synchronous rotating coordinate system rd 、i rq ;

[0040] An acquisition unit is used to obtain a DC component U of the stator voltage based on the stator voltage DC component U sd , U sq And the stator current DC component i sd 、i sqObtain the stator output active power P' and the stator output reactive power Q'; based on the stator output active power P' and the stator output reactive power Q', obtain the active power P after the low-pass filter and the reactive power Qv after the low-pass filter

[0041] Calculation unit, used to calculate the adaptive compensation frequency ω com , based on the adaptive compensation frequency ω com Get the compensation command △u of adaptive virtual damping control rd_ref ; Calculate the d-axis stator voltage command U in the synchronous rotating coordinate system ref and the d-axis stator voltage DC component U sd The deviation of the q-axis stator voltage command zero value and the q-axis stator voltage DC component U sq The deviation is input into the PI regulator of the stator voltage outer loop for processing, and the d-axis and q-axis rotor current instructions i are output. rd_ref 、i rq_ref ; Calculate the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system rd_ref and the rotor DC component i rd The deviation between the rotor current command i rq_ref and the rotor DC component i rq The deviation between them is input into the PI regulator of the rotor current inner loop to obtain the rotor voltage command u in the synchronous rotating coordinate system. rd_ref 、u rq_ref ;

[0042] Execution unit, used to convert the rotor voltage command u rd_ref The compensation command Δu of the adaptive virtual damping control rd_ref After superposition, the new rotor voltage command u is obtained rd_ref1 ; Set the new rotor voltage command u of the d-axis and q-axis rd_ref1 , rotor voltage command u rq_ref After modulation by the SVPWM link, the rotor-side converter switch control signal is generated, thereby achieving subsynchronous oscillation suppression of the doubly-fed wind power generation system.

[0043] Preferably, the acquisition unit is used to acquire the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc , by the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、isc Transform to obtain the stator three-phase voltage U sa , U sb , U sc The DC component U of the d-axis and q-axis stator voltage in the synchronous rotating coordinate system sd , U sq And the stator three-phase current i sa 、i sb 、i sc The DC components i of the d-axis and q-axis stator currents in the synchronous rotating coordinate system sd 、i sq , also used for:

[0044]

[0045] Among them, θ is the orientation angle of coordinate transformation, x A 、x B 、x C represents the three-phase stator voltage of the doubly-fed generator in the three-phase stationary coordinate system, x d 、x q Represents the d-axis and q-axis DC components of the stator voltage / current in the synchronous rotating coordinate system.

[0046] Preferably, the acquisition unit is used to acquire the three-phase rotor current i of the doubly-fed generator. ra 、i rb 、i rc and the rotor electrical angular velocity θ r , by the three-phase rotor current i ra 、i rb 、i rc and the rotor electrical angular velocity θ r Transform to obtain the three-phase rotor current i ra 、i rb 、i rc The d-axis and q-axis rotor DC components i in the synchronous rotating coordinate system rd 、i rq , also used for:

[0047]

[0048] Among them, θ r It is the electrical angular velocity of the doubly-fed generator rotor measured by the speed measuring device.

[0049] Preferably, the acquisition unit is used to obtain the stator voltage DC component U sd , U sq And the stator current DC component i sd 、i sqObtain the stator output active power P' and stator output reactive power Q', and also used for:

[0050]

[0051] Preferably, the acquisition unit is used to acquire the active power P after passing through the low-pass filter and the reactive power Q after passing through the low-pass filter based on the stator output active power P′ and the stator output reactive power Q′, and is also used to:

[0052]

[0053] Among them, ω f represents the cutoff frequency of the low-pass filter, and s represents the Laplace operator.

[0054] Preferably, the calculation unit is used to calculate the adaptive compensation frequency ω com , based on the adaptive compensation frequency ω com Get the compensation command Δu of adaptive virtual damping control rd_ref , also used for:

[0055] The collected single-phase grid-connected current is transformed by Fourier transform and the subsynchronous oscillation frequency f is obtained by the bubble method. c , using formula (39) to obtain the adaptive compensation frequency ω com , adaptive compensation frequency ω com Able to actively modulate its own parameters to suppress subsynchronous oscillations according to oscillation frequency and grid changes:

[0056] ω com =2*pi*(50-f c ) (26)

[0057] pi is the circumference of a circle, π.

[0058] Damping compensation is performed in the d-axis rotor current loop, and the compensation command Δu of the adaptive virtual damping control is obtained using equation (40): rd_ref :

[0059]

[0060] Among them, K com is the compensation coefficient of adaptive virtual damping.

[0061] Preferably, the calculation unit is used to calculate the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system. rd_ref and the rotor DC component i rd The deviation between the rotor current command i rq_ref and the rotor DC component i rqThe deviation between them is input into the PI regulator of the rotor current inner loop to obtain the rotor voltage command u in the synchronous rotating coordinate system. rd_ref 、u rq_ref , also used for:

[0062]

[0063] Among them, K p2 and K i2 They are the proportional coefficient and integral coefficient of the PI regulator in the rotor current loop respectively.

[0064] The technical solution of the present invention provides a method and system for suppressing subsynchronous oscillations of voltage source wind turbines, which solves the problem of suppressing subsynchronous oscillations of doubly fed wind power generation systems under weak power grids, and proposes a subsynchronous oscillation suppression method based on adaptive virtual damping control, in order to solve the subsynchronous oscillation problem caused by the interaction between doubly fed wind turbines and series compensated weak power grids, while eliminating the fixed parameter adaptation problem caused by the use of bandpass filters, thereby achieving virtual damping control of doubly fed wind power systems under weak power grids that can automatically adapt to power grid changes, output compensation voltage, increase damping to suppress subsynchronous oscillations, improve the stability margin of its virtual damping control strategy, and enhance the robustness of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0066] Figure 1 It is a flow chart of a method for suppressing subsynchronous oscillation of a voltage source wind turbine according to a preferred embodiment of the present invention;

[0067] Figure 2 A schematic diagram of adaptive virtual damping control of a voltage source DFIG system according to a preferred embodiment of the present invention; and

[0068] Figure 3 A structural diagram of a system for suppressing subsynchronous oscillation of a voltage source wind turbine generator set according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0069] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0070] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0071] Figure 1 The present invention is a flowchart of a method for suppressing subsynchronous oscillation of a voltage source wind turbine generator set according to a preferred embodiment of the present invention.

[0072] In order to solve the problem of subsynchronous oscillation suppression of a doubly fed wind power generation system under a weak power grid, the present invention proposes a subsynchronous oscillation suppression method based on adaptive virtual damping control, in order to solve the subsynchronous oscillation problem caused by the interaction between the doubly fed wind turbine set and the series compensated weak power grid, and at the same time eliminate the fixed parameter adaptation problem caused by the use of a bandpass filter, so that the virtual damping control of the doubly fed wind power system under a weak power grid can automatically adapt to the changes in the power grid, output a compensation voltage, increase the damping to suppress the subsynchronous oscillation, improve the stability margin of its virtual damping control strategy, and enhance the robustness of the system.

[0073] A subsynchronous oscillation suppression method based on adaptive virtual damping control is applied to a doubly-fed wind power generation system composed of a doubly-fed generator and a machine-side converter under a weak power grid, and is performed in the following steps.

[0074] like Figure 1 As shown, the present invention provides a method for suppressing subsynchronous oscillation of a voltage source wind turbine generator set, the method comprising:

[0075] Step 101: Collect the stator three-phase voltage U of the doubly-fed generator sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc , by the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc Transform and obtain the stator three-phase voltage U sa , U sb , U sc The DC component U of the d-axis and q-axis stator voltage in the synchronous rotating coordinate system sd , U sq And the stator three-phase current i sa 、i sb 、i scThe DC components i of the d-axis and q-axis stator currents in the synchronous rotating coordinate system sd 、i sq ;

[0076] Preferably, the stator three-phase voltage U of the double-fed generator is collected sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc , by the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc Transform and obtain the stator three-phase voltage U sa , U sb , U sc The DC component U of the d-axis and q-axis stator voltage in the synchronous rotating coordinate system sd , U sq And the stator three-phase current i sa 、i sb 、i sc The DC components i of the d-axis and q-axis stator currents in the synchronous rotating coordinate system sd 、i sq ,include:

[0077]

[0078] Among them, θ is the orientation angle of coordinate transformation, x A 、x B 、x C represents the three-phase stator voltage of the doubly-fed generator in the three-phase stationary coordinate system, x d 、x q Represents the d-axis and q-axis DC components of the stator voltage / current in the synchronous rotating coordinate system.

[0079] The present invention performs data collection and conversion on the stator side in step 101;

[0080] Sampling the stator three-phase voltage U of the doubly-fed generator sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc , and bring it into the coordinate transformation link shown in equation (30) to obtain the d-axis and q-axis DC components U of the stator voltage in the synchronous rotating coordinate system sd , U sqAnd the d-axis and q-axis DC components i of the stator current in the synchronous rotating coordinate system sd 、i sq :

[0081]

[0082] In formula (30), θ is the orientation angle of coordinate transformation, x A 、x B 、x C represents the three-phase stator voltage of the doubly-fed generator in the three-phase stationary coordinate system, x d 、x q Represents the d-axis and q-axis DC components of the stator voltage / current in the synchronous rotating coordinate system;

[0083] Step 102: Collect the three-phase rotor current i of the doubly-fed generator ra 、i rb 、i rc and the rotor electrical angular velocity θ r , by the three-phase rotor current i ra 、i rb 、i rc and the rotor electrical angular velocity θ r Transform to obtain the three-phase rotor current i ra 、i rb 、i rc The d-axis and q-axis rotor DC components i in the synchronous rotating coordinate system rd 、i rq ;

[0084] Preferably, the three-phase rotor current i of the doubly-fed generator is collected ra 、i rb 、i rc and the rotor electrical angular velocity θ r , by the three-phase rotor current i ra 、i rb 、i rc and the rotor electrical angular velocity θ r Transform to obtain the three-phase rotor current i ra 、i rb 、i rc The d-axis and q-axis rotor DC components i in the synchronous rotating coordinate system rd 、i rq ,include:

[0085]

[0086] Among them, θ r It is the electrical angular velocity of the doubly-fed generator rotor measured by the speed measuring device.

[0087] The present invention performs data collection and conversion on the rotor side in step 102;

[0088] Collect the three-phase rotor current i of the doubly fed generator ra 、i rb 、i rc and the rotor electrical angular velocity θ r , and bring it into the coordinate transformation link shown in equation (32) to obtain the d-axis and q-axis DC components i of the rotor current in the synchronous rotating coordinate system rd 、i rq :

[0089]

[0090] Step 103: Based on the stator voltage DC component U sd , U sq and the stator current DC component i sd 、i sq Obtain the stator output active power P′ and the stator output reactive power Q′;

[0091] Preferably, based on the stator voltage DC component U sd , U sq and the stator current DC component i sd 、i sq Obtaining the stator output active power P' and stator output reactive power Q' includes:

[0092]

[0094] The present invention performs power calculation and filtering in step 103;

[0095] The power calculation is performed using formula (34) to obtain the stator output active power P′ and stator output reactive power Q′:

[0096]

[0097] Step 104: obtaining the active power P after passing through the low-pass filter and the reactive power Q after passing through the low-pass filter based on the stator output active power P′ and the stator output reactive power Q′;

[0098] Preferably, obtaining the active power P after passing through the low-pass filter and the reactive power Q after passing through the low-pass filter based on the stator output active power P′ and the stator output reactive power Q′ comprises:

[0099]

[0100] Among them, ω f represents the cutoff frequency of the low-pass filter, and s represents the Laplace operator.

[0101] The present invention uses formula (36) in step 104 to obtain the active power P after passing through the low-pass filter and the reactive power Q after passing through the low-pass filter:

[0102]

[0103] In formula (36), ω f represents the cutoff frequency of the low-pass filter, and s represents the Laplace operator;

[0104] The power calculated above is mainly for the integrity of system control. In order to realize the dual closed-loop control of voltage and current, it is necessary to first obtain the stator voltage outer loop given instruction Uref through the power calculation and power control links, and then complete the dual closed-loop calculation of voltage and current in the subsequent steps.

[0105] Step 105: Calculate the adaptive compensation frequency ω com , based on the adaptive compensation frequency ω com Get the compensation command Δu of adaptive virtual damping control rd_ref ;

[0106] Preferably, the adaptive compensation frequency ω is calculated com , based on the adaptive compensation frequency ω com Get the compensation command Δu of adaptive virtual damping control rd_ref ,include:

[0107] The collected single-phase grid-connected current is transformed by Fourier transform and the subsynchronous oscillation frequency f is obtained by the bubble method. c , using formula (39) to obtain the adaptive compensation frequency ω com , adaptive compensation frequency ω com Able to actively modulate its own parameters to suppress subsynchronous oscillations according to oscillation frequency and grid changes:

[0108] ω com =2*pi*(50-f c ) (37)

[0109] pi is the circumference of a circle, π.

[0110] Damping compensation is performed in the d-axis rotor current loop, and the compensation command Δu of the adaptive virtual damping control is obtained using equation (40): rd_ref :

[0111]

[0112] Among them, K com is the compensation coefficient of adaptive virtual damping.

[0113] The present invention performs adaptive compensation frequency ω in step 105.com Calculation of

[0114] The collected single-phase grid-connected current is transformed by Fourier transform, and then a function is written to obtain the subsynchronous oscillation frequency f by the bubble method. c , using formula (39) to obtain the adaptive virtual damping compensation frequency ω com :

[0115] ω com =2*pi*(50-f c ) (39)

[0116] Step 5: Use equation (40) to obtain the compensation command Δu of the adaptive virtual damping control: rd_ref ;

[0117]

[0118] In formula (40), K com represents the compensation coefficient of adaptive virtual damping;

[0119] Step 106: Calculate the d-axis stator voltage command U in the synchronous rotating coordinate system ref and the d-axis stator voltage DC component U sd The deviation of the q-axis stator voltage command zero value and the q-axis stator voltage DC component U sq The deviation is input into the PI regulator of the stator voltage outer loop for processing, and the d-axis and q-axis rotor current instructions i are output. rd_ref 、i rq_ref ;

[0120] The present invention calculates the d-axis stator voltage command U in the synchronous rotating coordinate system in step 106. ref and d-axis stator voltage U sd The deviation of the q-axis stator voltage command zero value and the q-axis stator voltage U sq The deviation is input into the PI regulator of the stator voltage outer loop for processing, and the d-axis and q-axis rotor current instructions i are output. rd_ref 、i rq_ref ;

[0121] Step 107: Calculate the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system rd_ref and the rotor DC component i rd The deviation between the rotor current command i rq_ref and the rotor DC component i rq The deviation between them is input into the PI regulator of the rotor current inner loop to obtain the rotor voltage command u in the synchronous rotating coordinate system. rd_ref 、u rq_ref ;

[0122] Preferably, the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system are calculated. rd_ref and the rotor DC component i rd The deviation between the rotor current command i rq_ref and the rotor DC component i rq The deviation between them is input into the PI regulator of the rotor current inner loop to obtain the rotor voltage command u in the synchronous rotating coordinate system. rd_ref 、u rq_ref ,include:

[0123]

[0124] Among them, K p2 and K i2 They are the proportional coefficient and integral coefficient of the PI regulator in the rotor current loop respectively.

[0125] In step 107, the present invention calculates the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system. rd_ref With rotor current feedback i rd The deviation between the instructions rq_re f and i rq The deviation between them is input into the PI regulator of the rotor current inner loop, and the rotor voltage command u in the synchronous rotating coordinate system is obtained accordingly. rd_ref 、u rq_ref ;

[0126]

[0127] In formula (42), K p2 and K i2 They are the proportional coefficient and integral coefficient of the PI regulator in the rotor current loop respectively.

[0128] Step 108: Set the rotor voltage command u rd_ref Compensation command Δu with adaptive virtual damping control rd_ref After superposition, the new rotor voltage command u is obtained rd_ref1 ;

[0129] In step 108, the present invention sets the rotor voltage command u rd_ref and the adaptive virtual damping compensation command Δu rd_ref After superposition, the new rotor voltage command u is obtained rd_ref1 .

[0130] Step 109: Set the new rotor voltage instructions u for the d-axis and q-axis rd_ref1 , rotor voltage command u rq_ref After modulation by the SVPWM link, the rotor-side converter switch control signal is generated, thereby achieving subsynchronous oscillation suppression of the doubly-fed wind power generation system.

[0131] Step 9: d-axis and q-axis rotor voltage command u rd_ref1 、u rq_ref After modulation by the SVPWM link, rotor-side converter switch control signals S1-S6 are generated, thereby achieving subsynchronous oscillation suppression of the doubly-fed wind power generation system.

[0132] The present invention proposes a method of calculating the subsynchronous oscillation compensation frequency using an adaptive algorithm to realize the virtual damping control structure of the system, which can increase the system damping and effectively suppress the subsynchronous oscillation caused by insufficient damping of the system. Compared with the traditional scheme, it can better resist the interference of external environmental changes under weak power grid, thereby improving the stability of the doubly fed wind power generation system;

[0133] The present invention obtains the oscillation frequency of the subsynchronous oscillation of the grid-connected system by real-time monitoring of the grid-connected current and performing Fourier transform analysis on it, thereby dynamically adjusting its own parameters when the grid changes, and effectively reducing the complexity of parameter selection and calculation in virtual damping control;

[0134] The control strategy of the present invention only needs to utilize one electrical quantity, the grid-connected current, and only needs to generate one control parameter, thereby enhancing the flexibility and adaptability of the control and significantly improving the adaptive capability of the control loop.

[0135] The traditional method of additional damping control is to use a bandpass filter to extract the specific oscillation frequency of the signal and compensate it to the given signal through feedback control to increase the damping and suppress the oscillation of the system. The disadvantage of the bandpass filter is that the control parameters are fixed, it depends on the controller hardware, and it cannot adapt to complex and changeable systems. The key point and protection point of the present invention is the adaptive virtual damping control method adopted.

[0136] The present invention analyzes the input current signal by Fourier transform and bubbling algorithm, adaptively selects the compensation frequency of subsynchronous oscillation according to conditions, increases the system damping through virtual damping control, eliminates the fixed parameter adaptation problem caused by the use of bandpass filters, can effectively suppress the subsynchronous oscillation of the system, and increase the system stability.

[0137] The present invention dynamically adjusts its own parameters through adaptive virtual damping control, reasonably selects control parameters when the power grid changes, reduces the complexity of system calculation, and improves the flexibility and adaptability of the system control loop.

[0138] Figure 2 This is the block diagram of the adaptive virtual damping control of the voltage source DFIG system. Figure 2 The left dotted box is the block diagram of the adaptive rotor current loop virtual damping control. The two PI controllers in the rotor current inner loop are used to achieve fast zero-static tracking control of the rotor current. The output of the superimposed rotor voltage compensation command Δu rd_refIt is used to suppress subsynchronous oscillations, increase system damping, and improve the stability of the doubly-fed wind power generation system under series compensation of weak power grids.

[0139] Figure 3 A structural diagram of a system for suppressing subsynchronous oscillation of a voltage source wind turbine generator set according to a preferred embodiment of the present invention.

[0140] like Figure 3 As shown, the present invention provides a system for suppressing subsynchronous oscillation of a voltage source wind turbine generator set, the system comprising:

[0141] The acquisition unit 301 is used to acquire the stator three-phase voltage U of the double-fed generator. sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc , by the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc Transform and obtain the stator three-phase voltage U sa , U sb , U sc The DC component U of the d-axis and q-axis stator voltage in the synchronous rotating coordinate system sd , U sq And the stator three-phase current i sa 、i sb 、i sc The DC components i of the d-axis and q-axis stator currents in the synchronous rotating coordinate system sd 、i sq ; Collect the three-phase rotor current i of the doubly fed generator ra 、i rb 、i rc and the rotor electrical angular velocity θ r , by the three-phase rotor current i ra 、i rb 、i rc and the rotor electrical angular velocity θ r Transform to obtain the three-phase rotor current i ra 、i rb 、i rc The d-axis and q-axis rotor DC components i in the synchronous rotating coordinate system rd 、i rq ;

[0142] Preferably, the acquisition unit 301 is used to acquire the stator three-phase voltage U sa , U sb, U sc and the stator three-phase current i sa 、i sb 、i sc , by the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc Transform and obtain the stator three-phase voltage U sa , U sb , U sc The DC component U of the d-axis and q-axis stator voltage in the synchronous rotating coordinate system sd , U sq And the stator three-phase current i sa 、i sb 、i sc The DC components i of the d-axis and q-axis stator currents in the synchronous rotating coordinate system sd 、i sq , also used for:

[0143]

[0144] Among them, θ is the orientation angle of coordinate transformation, x A 、x B 、x C represents the three-phase stator voltage of the doubly-fed generator in the three-phase stationary coordinate system, x d 、x q Represents the d-axis and q-axis DC components of the stator voltage / current in the synchronous rotating coordinate system.

[0145] Preferably, the acquisition unit 301 is used to acquire the three-phase rotor current i of the doubly-fed generator. ra 、i rb 、i rc and the rotor electrical angular velocity θ r , by the three-phase rotor current i ra 、i rb 、i rc and the rotor electrical angular velocity θ r Transform to obtain the three-phase rotor current i ra 、i rb 、i rc The d-axis and q-axis rotor DC components i in the synchronous rotating coordinate system rd 、i rq , also used for:

[0146]

[0147] Among them, θ rIt is the electrical angular velocity of the doubly-fed generator rotor measured by the speed measuring device.

[0148] The acquisition unit 302 is used to obtain the stator voltage DC component U sd , U sq and the stator current DC component i sd 、i sq Obtain stator output active power P′ and stator output reactive power Q′; obtain active power P after passing through a low-pass filter and reactive power Q after passing through a low-pass filter based on the stator output active power P′ and stator output reactive power Q′;

[0149] Preferably, the acquisition unit 302 is used to obtain the stator voltage DC component U sd , U sq and the stator current DC component i sd 、i sq Obtain the stator output active power P' and stator output reactive power Q', and also used for:

[0150]

[0151] Preferably, the acquisition unit 302 is used to acquire the active power P after passing through the low-pass filter and the reactive power Q after passing through the low-pass filter based on the stator output active power P′ and the stator output reactive power Q′, and is also used to:

[0152]

[0153] Among them, ω f represents the cutoff frequency of the low-pass filter, and s represents the Laplace operator.

[0154] The calculation unit 303 is used to calculate the adaptive compensation frequency ω com , based on the adaptive compensation frequency ω com Get the compensation command Δu of adaptive virtual damping control rd_ref ; Calculate the d-axis stator voltage command U in the synchronous rotating coordinate system ref and the d-axis stator voltage DC component U sd The deviation of the q-axis stator voltage command zero value and the q-axis stator voltage DC component U sq The deviation is input into the PI regulator of the stator voltage outer loop for processing, and the d-axis and q-axis rotor current instructions i are output. rd_ref 、i rq_ref ; Calculate the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system rd_ref and the rotor DC component i rd The deviation between the rotor current command i rq_ref and the rotor DC component i rqThe deviation between them is input into the PI regulator of the rotor current inner loop to obtain the rotor voltage command u in the synchronous rotating coordinate system. rd_ref 、u rq_ref ;

[0155] Preferably, the calculation unit 303 is used to calculate the adaptive compensation frequency ω com , based on the adaptive compensation frequency ω com Get the compensation command Δu of adaptive virtual damping control rd_ref , also used for:

[0156] The collected single-phase grid-connected current is transformed by Fourier transform and the subsynchronous oscillation frequency f is obtained by the bubble method. c , using formula (39) to obtain the adaptive compensation frequency ω com , adaptive compensation frequency ω com Able to actively modulate its own parameters to suppress subsynchronous oscillations according to oscillation frequency and grid changes:

[0157] ω com =2*pi*(50-f c ) (47)

[0158] pi is the circumference of a circle, π.

[0159] Damping compensation is performed in the d-axis rotor current loop, and the compensation command Δu of the adaptive virtual damping control is obtained using equation (40): rd_ref :

[0160]

[0161] Among them, K com is the compensation coefficient of adaptive virtual damping.

[0162] Preferably, the calculation unit 303 is used to calculate the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system. rd_ref and the rotor DC component i rd The deviation between the rotor current command i rq_ref and the rotor DC component i rq The deviation between them is input into the PI regulator of the rotor current inner loop to obtain the rotor voltage command u in the synchronous rotating coordinate system. rd_ref 、u rq_ref , also used for:

[0163]

[0164] Among them, K p2 and K i2 They are the proportional coefficient and integral coefficient of the PI regulator in the rotor current loop respectively.

[0165] The execution unit 304 is used to convert the rotor voltage command u rd_ref Compensation command Δu with adaptive virtual damping control rd_ref After superposition, the new rotor voltage command u is obtained rd_ref1 ; Set the new rotor voltage command u of the d-axis and q-axis rd_ref1 , rotor voltage command u rq_ref After modulation by the SVPWM link, the rotor-side converter switch control signal is generated, thereby achieving subsynchronous oscillation suppression of the doubly-fed wind power generation system.

[0166] A system for suppressing subsynchronous oscillation of a voltage source wind turbine generator set in a preferred embodiment of the present invention corresponds to a method for suppressing subsynchronous oscillation of a voltage source wind turbine generator set in another preferred embodiment of the present invention, and will not be described in detail here.

[0167] 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. Moreover, 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 codes. The schemes in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0172] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0173] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

[0174] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / said / the [means, components, etc.]" are to be openly interpreted as at least one instance of the means, components, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily have to be performed in the exact order disclosed, unless explicitly stated otherwise.

Claims

1. A method for suppressing subsynchronous oscillation of a voltage source wind turbine, the method comprising: Collect the stator three-phase voltage U of the double-fed generator sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc , through the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc Transform to obtain the stator three-phase voltage U sa , U sb , U sc The DC component U of the d-axis and q-axis stator voltage in the synchronous rotating coordinate system sd , U sq And the stator three-phase current i sa 、i sb 、i sc The DC components i of the d-axis and q-axis stator currents in the synchronous rotating coordinate system sd 、i sq ; Collect the three-phase rotor current i of the doubly fed generator ra 、i rb 、i rc and the rotor electrical angular velocity θ r , by the three-phase rotor current i ra 、i rb 、i rc and the rotor electrical angular velocity θ r Transform to obtain the three-phase rotor current i ra 、i rb 、i rc The d-axis and q-axis rotor DC components i in the synchronous rotating coordinate system rd 、i rq ; Based on the stator voltage DC component U sd , U sq And the stator current DC component i sd 、i sd Obtain the stator output active power P′ and the stator output reactive power Q′; Based on the stator output active power P′ and the stator output reactive power Q, the active power P after passing through the low-pass filter and the reactive power Q after passing through the low-pass filter are obtained; Calculate the adaptive compensation frequency ω com , based on the adaptive compensation frequency ω com Get the compensation command Δu of adaptive virtual damping control rd_ref ; Calculate the d-axis stator voltage command U in the synchronous rotating coordinate system ref and the d-axis stator voltage DC component U sd The deviation of the q-axis stator voltage command zero value and the q-axis stator voltage DC component U sq The deviation is input into the PI regulator of the stator voltage outer loop for processing, and the d-axis and q-axis rotor current instructions i are output. rd_ref 、i rq_ref ; Calculate the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system rd_ref and the rotor DC component i rd The deviation between the rotor current command i rq_ref and the rotor DC component i rq The deviation between them is input into the PI regulator of the rotor current inner loop to obtain the rotor voltage command u in the synchronous rotating coordinate system. rd_ref 、u rq_ref ; The rotor voltage command u rd_ref The compensation command Δu of the adaptive virtual damping control rd_ref After superposition, the new rotor voltage command u is obtained rd_ref1 ; The new rotor voltage command u of the d-axis and q-axis rd_ref1 , rotor voltage command u rq_ref After modulation by the SVPWM link, the rotor-side converter switch control signal is generated, thereby achieving subsynchronous oscillation suppression of the doubly-fed wind power generation system.

2. The method according to claim 1, wherein the stator three-phase voltage U of the doubly-fed generator is collected sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc , through the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc Transform to obtain the stator three-phase voltage U sa , U sb , U sc The DC component U of the d-axis and q-axis stator voltage in the synchronous rotating coordinate system sd , U sq And the stator three-phase current i sa 、i sb 、i sc The DC components i of the d-axis and q-axis stator currents in the synchronous rotating coordinate system sd 、i sq ,include: Among them, θ is the orientation angle of coordinate transformation, x A 、x B 、x C represents the three-phase stator voltage of the doubly-fed generator in the three-phase stationary coordinate system, x d 、x q Represents the d-axis and q-axis DC components of the stator voltage / current in the synchronous rotating coordinate system.

3. The method according to claim 2, wherein the three-phase rotor current i of the double-fed generator is collected ra 、i rb 、i rc and the rotor electrical angular velocity θ r , by the three-phase rotor current i ra 、i rb 、i rc and the rotor electrical angular velocity θ r Transform to obtain the three-phase rotor current i ra 、i rb 、i rc The d-axis and q-axis rotor DC components i in the synchronous rotating coordinate system rd 、i rq ,include: Among them, θ r It is the electrical angular velocity of the doubly-fed generator rotor measured by the speed measuring device.

4. The method according to claim 3, wherein the stator voltage DC component U sd , U sq And the stator current DC component i sd 、i sq Obtaining the stator output active power P' and stator output reactive power Q' includes:

5. The method according to claim 4, wherein the step of obtaining the active power P after passing through a low-pass filter and the reactive power Q after passing through a low-pass filter based on the stator output active power P′ and the stator output reactive power Q′ comprises: Among them, ω f represents the cutoff frequency of the low-pass filter, and s represents the Laplace operator.

6. The method according to claim 5, wherein the calculating the adaptive compensation frequency ω com , based on the adaptive compensation frequency ω com Get the compensation command Δu of adaptive virtual damping control rd_ref ,include: The collected single-phase grid-connected current is transformed by Fourier transform and the subsynchronous oscillation frequency f is obtained by the bubble method. c , using formula (39) to obtain the adaptive compensation frequency ω com , adaptive compensation frequency ω com Able to actively modulate its own parameters to suppress subsynchronous oscillations according to oscillation frequency and grid changes: ω com =2*pi*(50-f c ) (5) pi is the ratio of a circle to its circumference; Damping compensation is performed in the d-axis rotor current loop, and the compensation command Δu of the adaptive virtual damping control is obtained using equation (40): rd_ref : Among them, K com is the compensation coefficient of adaptive virtual damping.

7. The method according to claim 6, wherein the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system are calculated. rd_ref and the rotor DC component i rd The deviation between the rotor current command i rq_ref and the rotor DC component i rd The deviation between them is input into the PI regulator of the rotor current inner loop to obtain the rotor voltage command u in the synchronous rotating coordinate system. rq_ref 、u rq_ref ,include: Among them, K p2 and K i2 They are the proportional coefficient and integral coefficient of the PI regulator in the rotor current loop respectively.

8. A system for suppressing subsynchronous oscillation of a voltage source wind turbine, the system comprising: The acquisition unit is used to collect the stator three-phase voltage U of the double-fed generator. sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc , through the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc Transform to obtain the stator three-phase voltage U sa , U sb , U sc The DC component U of the d-axis and q-axis stator voltage in the synchronous rotating coordinate system sd , U sq And the stator three-phase current i sa 、i sb 、i sc The DC components i of the d-axis and q-axis stator currents in the synchronous rotating coordinate system sd 、i sq ; Collect the three-phase rotor current i of the doubly fed generator ra 、i rb 、i rc and the rotor electrical angular velocity θ r , by the three-phase rotor current i ra 、i rb 、i rc and the rotor electrical angular velocity θ r Transform to obtain the three-phase rotor current i ra 、i rb 、i rc The d-axis and q-axis rotor DC components i in the synchronous rotating coordinate system rd 、i rq ; An acquisition unit is used to obtain a DC component U of the stator voltage based on the stator voltage DC component U sd , U sq And the stator current DC component i sd 、i sq Obtaining stator output active power P′ and stator output reactive power Q′; obtaining active power P after passing through a low-pass filter and reactive power Q after passing through a low-pass filter based on the stator output active power P′ and the stator output reactive power Q′; Calculation unit, used to calculate the adaptive compensation frequency ω com , based on the adaptive compensation frequency ω com Get the compensation command Δu of adaptive virtual damping control rd_ref ; Calculate the d-axis stator voltage command U in the synchronous rotating coordinate system ref and the d-axis stator voltage DC component U sd The deviation of the q-axis stator voltage command zero value and the q-axis stator voltage DC component U sq The deviation is input into the PI regulator of the stator voltage outer loop for processing, and the d-axis and q-axis rotor current instructions I are output. rd_ref 、i rq_ref ; Calculate the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system rd_ref and the rotor DC component i rd The deviation between the rotor current command i rq_ref and the rotor DC component i rq The deviation between them is input into the PI regulator of the rotor current inner loop to obtain the rotor voltage command u in the synchronous rotating coordinate system. rd_ref 、u rq_ref ; Execution unit, used to convert the rotor voltage command u rd_ref The compensation command Δu of the adaptive virtual damping control rd_ref After superposition, the new rotor voltage command u is obtained rd_ref1 ; Set the new rotor voltage command u of the d-axis and q-axis rd_ref1 , rotor voltage command u rq_ref After modulation by the SVPWM link, the rotor-side converter switch control signal is generated, thereby achieving subsynchronous oscillation suppression of the doubly-fed wind power generation system.

9. The system according to claim 8, wherein the acquisition unit is used to acquire the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc , through the stator three-phase voltage U sa , U sb , U sc and the stator three-phase current i sa 、i sb 、i sc Transform to obtain the stator three-phase voltage U sa , U sb , U sc The DC component U of the d-axis and q-axis stator voltage in the synchronous rotating coordinate system sd , U sq And the stator three-phase current i sa 、i sb 、i sc The DC components i of the d-axis and q-axis stator currents in the synchronous rotating coordinate system sd 、i sq , also used for: in, θ is the orientation angle of the coordinate transformation, x A 、x B 、x C represents the three-phase stator voltage of the doubly-fed generator in the three-phase stationary coordinate system, x d 、x q Represents the d-axis and q-axis DC components of the stator voltage / current in the synchronous rotating coordinate system.

10. The system according to claim 9, wherein the acquisition unit is used to acquire the three-phase rotor current i of the double-fed generator ra 、i rb 、i rc and the rotor electrical angular velocity θ r , by the three-phase rotor current i ra 、i rb 、i rc and the rotor electrical angular velocity θ r Transform to obtain the three-phase rotor current i ra 、i rb 、i rc The d-axis and q-axis rotor DC components i in the synchronous rotating coordinate system rd 、i rq , also used for: in, θ r It is the electrical angular velocity of the doubly-fed generator rotor measured by the speed measuring device.

11. The system according to claim 10, wherein the acquisition unit is configured to obtain a DC component U of the stator voltage based on the DC component U of the stator voltage. sd , U sq And the stator current DC component i sd 、i sq Obtain the stator output active power P' and stator output reactive power Q', and also used for: 。 12. The system according to claim 11, wherein the acquisition unit is used to acquire the active power P after passing through the low-pass filter and the reactive power Q after passing through the low-pass filter based on the stator output active power P′ and the stator output reactive power Q′, and is also used to: in, ω f represents the cutoff frequency of the low-pass filter, and s represents the Laplace operator.

13. The system according to claim 12, wherein the calculation unit is used to calculate the adaptive compensation frequency ω com , based on the adaptive compensation frequency ω com Get the compensation command Δu of adaptive virtual damping control rd_ref , also used for: The collected single-phase grid-connected current is transformed by Fourier transform and the subsynchronous oscillation frequency f is obtained by the bubble method. c , using formula (39) to obtain the adaptive compensation frequency ω com , adaptive compensation frequency ω com Able to actively modulate its own parameters to suppress subsynchronous oscillations according to oscillation frequency and grid changes: ω com =2*pi*(50-f c ) (12) pi is the ratio of a circle to its circumference; Damping compensation is performed in the d-axis rotor current loop, and the compensation command Δu of the adaptive virtual damping control is obtained using equation (40): rd_ref : in, K com is the compensation coefficient of adaptive virtual damping.

14. The system according to claim 13, wherein the calculation unit is used to calculate the d-axis and q-axis rotor current instructions i in the synchronous rotating coordinate system. rd_ref and the rotor DC component i rd The deviation between the rotor current command i rq_ref and the rotor DC component i rq The deviation between them is input into the PI regulator of the rotor current inner loop to obtain the rotor voltage command u in the synchronous rotating coordinate system. rd_ref 、u rq_ref , also used for: in, K p2 and K i2 They are the proportional coefficient and integral coefficient of the PI regulator in the rotor current loop respectively.

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