CN118040798B - Additional damping control method and device for doubly-fed wind generator - Google Patents

Abstract

The present invention discloses an additional damping control method and device for a doubly-fed wind turbine generator. The method comprises: generating a dq axis inner loop current reference value; passing the measured dq axis current component through a DC isolation link and a gain link to generate an additional part of the dq axis inner loop current reference value; adding the dq axis inner loop current reference value and the additional part of the dq axis inner loop current reference value to generate a dq axis inner loop output current reference value; generating a dq axis excitation voltage reference wave according to the dq axis inner loop output current reference value, the measured dq axis current component, and the measured rotor side current; generating an excitation voltage reference wave in a three-phase stationary coordinate system according to the dq axis excitation voltage reference wave, the excitation voltage reference wave in the three-phase stationary coordinate system is used to generate a PWM modulation signal, and the PWM modulation signal is used to control the power device set in the machine-side converter. This is conducive to improving the damping characteristics and enhancing the stability of the power system after grid connection.

Description

Additional damping control method and device for double-fed wind turbine generator

Technical Field

The invention belongs to the technical field of doubly-fed wind turbine control, and in particular relates to an additional damping control method and device for a doubly-fed wind turbine generator.

Background Art

Doubly-fed wind turbines (hereinafter referred to as doubly-fed wind turbines) are one of the mainstream models in the global wind power field. The stator side is directly connected to the grid, and the rotor side is connected to the grid through a back-to-back converter. Electric power can be exchanged with the grid through the stator and rotor dual channels.

The back-to-back converter control in the doubly-fed wind turbine enables the wind turbine speed to be decoupled from the grid-side frequency. In addition, due to the volatility, randomness and intermittency of wind energy, the large-scale grid connection of doubly-fed wind turbines will reduce the overall damping of the power system, causing a significant impact on the stability of the power system.

Summary of the invention

In view of the deficiencies in the prior art, the present invention provides an additional damping control method and device for a doubly-fed wind turbine generator, so as to solve the problem that the damping level of the current doubly-fed wind turbine is insufficient and affects the stable operation of the power system.

In a first aspect, the present invention provides an additional damping control method for a doubly-fed wind turbine generator, comprising:

Generate dq axis inner loop current reference value;

The measured dq axis current components are passed through a DC isolation link and a gain link to generate an additional part of the dq axis inner loop current reference value;

Adding the dq axis inner loop current reference value and the additional part of the dq axis inner loop current reference value to generate a dq axis inner loop output current reference value;

Generate a dq axis excitation voltage reference wave according to the dq axis inner ring output current reference value, the measured dq axis current component, and the measured rotor side current;

According to the dq-axis excitation voltage reference wave, an excitation voltage reference wave in a three-phase stationary coordinate system is generated, and the excitation voltage reference wave in the three-phase stationary coordinate system is used to generate a PWM modulation signal, and the PWM modulation signal is used to control the power device set in the machine-side converter.

Furthermore, before generating the dq axis inner loop current reference value, the method further includes:

The measured rotor side current is subjected to a Park transformation to obtain a measured q-axis rotor side current and a measured d-axis rotor side current; the measured output current is subjected to a Park transformation to obtain a measured q-axis current component and a measured d-axis current component; wherein the angle required for the Park transformation is a grid angle calculated based on a grid reference frequency through virtual phase locking.

Further, generating the dq axis inner loop current reference value includes:

The measured q-axis current component is introduced into the voltage differential adjustment link to generate a differential adjustment output; the differential adjustment output is added to the deviation between the measured AC voltage and the reference voltage, and the q-axis inner loop current reference value is generated through PI control.

Furthermore, the step of passing the measured dq axis current components through a DC isolation link and a gain link to generate an additional part of the dq axis inner loop current reference value includes:

The measured d-axis current component passes through the d-axis DC isolation link and the d-axis gain link to generate an additional part of the d-axis inner loop current reference value;

The measured q-axis current component is passed through the q-axis DC isolation link and the q-axis gain link to generate the additional part of the q-axis inner loop current reference value.

Further, the adding of the dq axis inner loop current reference value and the additional part of the dq axis inner loop current reference value to generate the dq axis inner loop output current reference value includes:

Adding the d-axis inner loop current reference value and the additional part of the d-axis inner loop current reference value, and subjecting the result to amplitude limiting control, to generate a d-axis inner loop output current reference value;

The q-axis inner loop current reference value and the additional part of the q-axis inner loop current reference value are added, and after amplitude limiting control, a q-axis inner loop output current reference value is generated.

Further, generating a dq axis excitation voltage reference wave according to the dq axis inner ring output current reference value, the measured output current, and the measured rotor side current includes:

The deviation between the d-axis inner ring output current reference value and the measured d-axis current component is subjected to PI control to generate a d-axis rotor side current reference value;

The deviation between the d-axis rotor side current reference value and the measured d-axis rotor side current is subjected to PI control, and a feedforward cross-decoupling term generated according to the measured q-axis rotor side current is introduced to generate a d-axis excitation voltage reference wave.

Further, generating a dq axis excitation voltage reference wave according to the dq axis inner ring output current reference value, the measured output current, and the measured rotor side current includes:

The deviation between the q-axis inner ring output current reference value and the measured q-axis current component is subjected to PI control to generate a q-axis rotor side current reference value;

The deviation between the q-axis rotor side current reference value and the measured q-axis rotor side current is subjected to PI control, and a feedforward cross-decoupling term generated according to the measured d-axis rotor side current is introduced to generate a q-axis excitation voltage reference wave.

Further, generating an excitation voltage reference wave in a three-phase stationary coordinate system according to the dq-axis excitation voltage reference wave includes:

The q-axis excitation voltage reference wave and the d-axis excitation voltage reference wave are subjected to Park inverse transformation to generate an excitation voltage reference wave in a three-phase stationary coordinate system, wherein the angle required for Park inverse transformation is the deviation between the grid angle and the rotor angle calculated through virtual phase locking based on the grid reference frequency.

Further, generating the dq axis inner loop current reference value includes:

The deviation between the measured frequency and the reference frequency is controlled by PI to generate an active reference value; the deviation between the active reference value and the measured active value is controlled by PI to generate a d-axis inner loop current reference value.

In a second aspect, the present invention provides an additional damping control device for a doubly-fed wind turbine generator, comprising:

An inner loop current reference value generation module, used for generating dq axis inner loop current reference values;

The additional part generating module is used to generate the additional part of the dq axis inner loop current reference value by passing the measured dq axis current components through the DC isolation link and the gain link;

An output current reference value generating module, used for adding the dq axis inner loop current reference value and the additional part of the dq axis inner loop current reference value to generate a dq axis inner loop output current reference value;

The excitation voltage reference wave generation module is used to generate a dq axis excitation voltage reference wave according to the dq axis inner ring output current reference value, the measured dq axis current component, and the measured rotor side current; based on the dq axis excitation voltage reference wave, an excitation voltage reference wave in a three-phase stationary coordinate system is generated, and the excitation voltage reference wave in the three-phase stationary coordinate system is used to generate a PWM modulation signal, and the PWM modulation signal is used to control the power devices set in the machine-side converter.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG1 is a flow chart of an additional damping control method for a doubly-fed wind turbine generator according to a preferred embodiment of the present invention;

FIG2 is a schematic structural diagram of an additional damping control device for a doubly-fed wind generator according to a preferred embodiment of the present invention;

FIG3A is an overall control block diagram of an additional damping control method according to a preferred embodiment of the present invention;

FIG3B is a block diagram of an outer loop current control method in an additional damping control method according to a preferred embodiment of the present invention;

FIG3C is a block diagram of inner loop current control in the additional damping control method according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION

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.

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.

With the proposal of the "dual carbon" goal, wind power generation, as an important part of the new power system, has developed rapidly in recent years. In 2021, the country's new grid-connected wind power installed capacity was 47.57 million kilowatts; the national wind power generation was 652.6 billion kilowatt-hours, a year-on-year increase of 40.5%; the average utilization rate of wind power was 96.9%, an increase of 0.4% year-on-year. By the end of 2021, the country's cumulative installed wind power capacity was 328 million kilowatts, and wind power generation achieved new development.

As shown in FIG3A , the stator of the doubly-fed wind turbine is electrically connected to the AC grid (via a transformer) and has the same potential as the AC voltage at the grid connection point; the rotor side is connected to the grid through a back-to-back converter, which includes a rotor-side converter (also called a machine-side converter) and a grid-side converter, and the grid-side converter is electrically connected to the AC grid; the electric power can be exchanged with the grid through the stator and rotor dual channels.

The control strategy of the back-to-back converter belongs to the current source control method based on the phase-locked loop. Among them, the grid-side converter adopts the grid voltage oriented vector control, including the voltage outer loop and the current inner loop control, which is used for the DC link voltage control and the AC input waveform and power factor control. The rotor-side converter adopts the stator voltage oriented vector control, including the power outer loop and the current inner loop, to realize the power control of the doubly fed wind turbine. In this way, the wind turbine speed is decoupled from the grid-side frequency. After the large-scale grid connection of the doubly fed wind turbine, the overall damping of the system will be reduced. In addition, the volatility, randomness and intermittency of wind energy have a significant impact on the stability of the power system.

The present invention proposes an additional damping control method for a doubly-fed wind turbine. The grid-side converter of the doubly-fed wind turbine adopts a traditional vector control strategy to maintain the stability of the DC bus voltage. The machine-side converter adds a fixed frequency control link, a voltage closed-loop external damping control link based on a voltage difference adjustment link, an internal damping control link based on the actual feedback of the inner-loop current, and an inner-loop current control link. In this way, the additional inner and outer loop damping links are conducive to improving the damping characteristics of the doubly-fed wind turbine and enhancing the stability of the power system after the doubly-fed wind turbine is connected to the grid.

The additional damping control method of the doubly-fed wind turbine provided by the present invention can achieve effective regulation of the AC voltage at the grid connection point through additional inner and outer loop damping control links, which is beneficial to improving the damping characteristics of the doubly-fed wind turbine grid connection and enhancing the stability of the power system after the doubly-fed wind turbine grid connection. The additional damping control method can play an important role in the friendly access of wind power, improve the level of wind energy consumption, and promote the development and utilization of new energy.

As shown in FIG1 , the present invention provides an additional damping control method for a doubly-fed wind turbine generator, comprising the following steps:

S10: Generate dq axis inner ring current reference value;

S20: The measured dq axis current components are passed through a DC isolation link and a gain link to generate an additional part of the dq axis inner loop current reference value;

S30: adding the dq axis inner loop current reference value and the additional part of the dq axis inner loop current reference value to generate a dq axis inner loop output current reference value;

S40: Generate a dq axis excitation voltage reference wave according to the dq axis inner ring output current reference value, the measured dq axis current component, and the measured rotor side current; generate an excitation voltage reference wave in a three-phase stationary coordinate system according to the dq axis excitation voltage reference wave, the excitation voltage reference wave in the three-phase stationary coordinate system is used to generate a PWM modulation signal, and the PWM modulation signal is used to control the power devices set in the machine-side converter.

In some embodiments, as shown in FIG3A , before generating the dq axis inner loop current reference value, the method further includes:

The measured rotor side current I _rabc is subjected to a Park transformation to obtain the measured q-axis rotor side current I _rq and the measured d-axis rotor side current I _rd ; the measured output current I _abc is subjected to a Park transformation to obtain the measured q-axis current component I _q and the measured d-axis current component I _d ; wherein the angle θ required for the Park transformation is the grid angle calculated based on the grid reference frequency f ^* through virtual phase locking.

The grid angle θ can be obtained by virtual phase-locking calculation based on the grid reference frequency f ^* and the measured three-phase AC voltage (ie, the grid connection point AC voltage) _Uabc .

In some embodiments, as shown in FIG. 3A and FIG. 3B , generating the dq axis inner loop current reference value includes:

The measured q-axis current component _Iq is introduced into the voltage differential adjustment link to generate a differential adjustment output; the differential adjustment output is added to the measured _AC voltage Vac (which is the effective value of the three-phase voltage determined according to the aforementioned three-phase AC voltage _Uabc ) and the reference voltage The deviation of the stator voltage reference value is controlled by PI to generate the q-axis inner loop current reference value.

In some embodiments, as shown in FIG. 3A and FIG. 3B , generating the dq axis inner loop current reference value includes:

The deviation between the measured frequency f and the reference frequency f ^* is controlled by PI to generate an active reference value; the deviation between the active reference value P ^* and the measured active value P is controlled by PI to generate a d-axis inner loop current reference value

In some embodiments, as shown in FIG. 3A and FIG. 3B , the measured dq axis current components are passed through a DC isolation link and a gain link to generate an additional part of the dq axis inner loop current reference value, including:

The measured d-axis current component _Id is passed through the d-axis DC isolation link and the d-axis gain link to generate the additional part of the d-axis inner loop current reference value

The measured q-axis current component _Iq is passed through the q-axis DC isolation link and the q-axis gain link to generate the additional part of the q-axis inner loop current reference value

In some embodiments, as shown in FIG. 3A and FIG. 3B , adding the dq axis inner loop current reference value and the additional part of the dq axis inner loop current reference value to generate the dq axis inner loop output current reference value includes:

The d-axis inner loop current reference value Additional part of the d-axis inner loop current reference value Add and generate the d-axis inner ring output current reference value through limiting control

The q-axis inner loop current reference value Additional part of the q-axis inner loop current reference value Add and generate the q-axis inner loop output current reference value through limiting control

In some embodiments, as shown in FIG. 3A and FIG. 3C , generating a dq axis excitation voltage reference wave according to the dq axis inner ring output current reference value, the measured output current, and the measured rotor side current includes:

The d-axis inner ring output current reference value The deviation from the measured d-axis current component _Id is controlled by PI to generate a d-axis rotor side current reference value

The d-axis rotor side current reference value The deviation from the measured d-axis rotor side current i _rd is PI controlled, and a feedforward cross-decoupling term generated according to the measured q-axis rotor side current i _rq is introduced to generate a d-axis excitation voltage reference wave u _rd .

In some embodiments, as shown in FIG. 3A and FIG. 3C , generating a dq axis excitation voltage reference wave according to the dq axis inner ring output current reference value, the measured output current, and the measured rotor side current includes:

The q-axis inner loop output current reference value The deviation from the measured q-axis current component _Iq is controlled by PI to generate a q-axis rotor side current reference value

The q-axis rotor side current reference value The deviation from the measured q-axis rotor side current i _rq is subjected to PI control, and a feedforward cross-decoupling term generated according to the measured d-axis rotor side current i _rd is introduced to generate a q-axis excitation voltage reference u _rq .

In some embodiments, as shown in FIG3A , generating an excitation voltage reference wave in a three-phase stationary coordinate system according to the dq-axis excitation voltage reference wave includes:

The q-axis excitation voltage reference wave u _rq and the d-axis excitation voltage reference wave u _rd are subjected to Park inverse transformation to generate excitation voltage reference waves in a three-phase stationary coordinate system, wherein the angle required for Park inverse transformation is the deviation between the grid angle calculated through virtual phase locking according to the grid reference frequency and the measured rotor angle.

As shown in FIG2 , an additional damping control device 100 for a doubly-fed wind turbine generator according to an embodiment of the present invention comprises:

An inner loop current reference value generating module 110, used to generate dq axis inner loop current reference values;

The additional part generating module 120 is used to generate the additional part of the dq axis inner loop current reference value by passing the measured dq axis current components through the DC isolation link and the gain link;

An output current reference value generating module 130, configured to add the dq axis inner loop current reference value and the additional part of the dq axis inner loop current reference value to generate a dq axis inner loop output current reference value;

The excitation voltage reference wave generating module 140 is used to generate a dq axis excitation voltage reference wave according to the dq axis inner ring output current reference value, the measured dq axis current component, and the measured rotor side current; and to generate an excitation voltage reference wave in a three-phase stationary coordinate system according to the dq axis excitation voltage reference wave, wherein the excitation voltage reference wave in the three-phase stationary coordinate system is used to generate a PWM modulation signal, and the PWM modulation signal is used to control the power devices provided in the machine-side converter.

As shown in FIG3A , the additional damping control device 100 for a doubly-fed wind turbine according to an embodiment of the present invention is used for a rotor-side converter, and the rotor-side converter further includes: a PWM generator and a power device; an excitation voltage reference wave in a three-phase stationary coordinate system generated by the control device is sent to the PWM generator as a control command signal; the PWM generator generates a drive signal in response to the voltage reference wave, and the drive signal controls the action of the power device, wherein the power device may be a switch tube.

In some embodiments, as shown in FIG. 3A, FIG. 3B and FIG. 3C, when implementing the additional damping control method for a doubly-fed wind turbine generator according to the embodiment of the present invention, the overall control design is first performed. Specifically, the grid-side converter continues to adopt the traditional vector control strategy to maintain the DC bus voltage stability, which will not be described in detail. The rotor-side converter is based on V/F constant voltage and constant frequency control, and a given AC side reference voltage (such as the grid reference voltage) is set. That is, the stator side voltage reference value) and reference frequency (such as the grid reference frequency or the AC side reference frequency of 50Hz), the grid angle θ required for the AC voltage and current dq decomposition in the three-phase stationary coordinate system is calculated by the virtual phase lock with a reference frequency of 50Hz. The control strategy of the rotor side converter is determined to include fixed frequency control, outer loop damping control, inner loop damping control, current loop control and PWM modulation.

Specifically, as shown in FIG3A and FIG3B, the fixed frequency control link includes: in the d-axis current control link of the machine-side converter, the deviation between the measured frequency f and the reference frequency f ^* is subjected to PI control to obtain an active reference value P ^* , and then the deviation between the measured active value P and the measured active value P is subjected to PI control again to obtain a d-axis inner loop current reference value Or the d-axis inner loop current reference value obtained from the outer loop. The fixed frequency control link can use the following expression:

Where K _Pf is the frequency power PI control parameter, is the d-axis inner loop current reference value obtained by the outer loop, K _PP and K _IP are power current PI control parameters. In specific implementation, the PI control parameters are reasonably selected according to the inherent parameters or control parameters of the converter, and will not be described in detail.

Specifically, as shown in FIG3A and FIG3B, the external damping control link includes: in the q-axis current control link of the machine-side converter, a voltage closed-loop external damping control link based on the voltage differential adjustment link is connected in series. The voltage differential adjustment link introduces the measured q-axis current component _Iq (such as the measured q-axis current), and obtains the differential adjustment output after passing through the current and voltage isolation link and the current and voltage gain link. Then, the differential adjustment output is added to the measured _AC voltage Vac as the differential adjustment voltage _v'ac . Then, the differential adjustment voltage is compared with the reference voltage (such as AC voltage reference value) to perform voltage and current PI control to obtain the q-axis inner loop current reference value Or the q-axis inner loop current reference value obtained from the outer loop. The external damping control link can be expressed as follows:

Among them, _Xc is the current and voltage gain coefficient, that is, the current and voltage adjustment coefficient, T is the time constant of the current and voltage isolation link, and _KPv and _KIv are the voltage and current PI control parameters. In specific implementation, the PI control parameters are reasonably selected according to the inherent parameters or control parameters of the converter, and no further details are given.

During steady-state operation, due to the action of the DC isolation link, the differential signal is 0; when a disturbance occurs in the system, the measured AC voltage is supplemented by the differential coefficient and the time constant of the DC isolation link to achieve flexible adjustment of the AC side voltage, which is beneficial to enhancing the system voltage stability.

Specifically, as shown in FIG3A and FIG3B, the internal damping control link includes: in the d-axis and q-axis current control links of the generator-side converter, an internal damping control based on the actual feedback of the inner loop current is connected in series. Specifically, the measured output current reflecting the system oscillation, such as the measured d-axis current I _d and the measured q-axis current I _q , is introduced as the feedforward input, and passes through the DC isolation link and the gain link respectively to generate the additional part of the dq-axis inner loop current reference value. The current command signal (such as the q-axis inner loop current reference value D-axis inner ring current reference value The dq axis inner loop current reference value and its additional part are controlled by limiting to generate the stator output current dq axis reference value, that is, the dq axis inner loop output current reference value The internal damping control link can be expressed as follows:

in, are the dq axis reference value limit boundaries respectively. If the input exceeds the boundary, the output takes the boundary value. K is the gain coefficient, and _Tw is the DC isolation link time constant. In specific implementation, the gain coefficient and the DC isolation link time constant are reasonably selected according to the inherent parameters or control parameters of the converter, and no further details are given.

When the system is disturbed, the current command signal (such as the q-axis inner loop current reference value) is adjusted by the DC isolation link time constant and gain coefficient. D-axis inner ring current reference value ) is used to supplement the inverter so as to achieve flexible adjustment of the damping characteristics of the inverter.

Specifically, as shown in FIG. 3A and FIG. 3C , the inner loop current control link includes: outputting the stator reference current The deviation from the measured current (such as the measured d-axis current I _d , the measured q-axis current I _q ) is used to perform inner loop current PI control to obtain the rotor side current reference value Then the rotor side current reference value The deviation from the measured value (such as the measured d-axis rotor side current i _rd and the measured q-axis rotor side current i _rq ) is PI controlled, and the feedforward cross-decoupling term is introduced to obtain the excitation voltage reference wave, such as the q-axis excitation voltage reference wave u _rq and the d-axis excitation voltage reference wave u _rd . The inner loop current control link can be expressed as follows:

Among them, ω ₁ L _m I _q , ω ₁ L _r i _rq , ω ₁ L _m I _d , and ω ₁ L _r i _rd are all decoupling items introduced in the control link, which will not be described in detail. K _Pd1 and K _Id1 are the first PI control parameters of the d-axis, and K _Id2 and K _Id2 are the second PI control parameters of the d-axis; K _Pq1 and K _Iq1 are the first PI control parameters of the q-axis, and K _Pq2 and K _Iq2 are the second PI control parameters of the q-axis. In specific implementation, each PI control parameter is reasonably selected according to the inherent parameters or control parameters of the converter, which will not be described in detail.

Specifically, as shown in FIG3A , the PWM modulation link includes: performing a Park inverse transformation on the excitation voltage reference wave under the dq axis to obtain the excitation voltage reference wave under the three-phase stationary coordinate system, and using this signal as the PWM modulation signal of the converter to realize the control of the converter switch tube.

In summary, the additional damping control method for the doubly-fed wind turbine provided by the present invention can achieve effective regulation of the AC voltage at the grid connection point through the additional inner and outer loop damping control links, which is conducive to improving the damping characteristics of the doubly-fed wind turbine grid connection and improving the stability of the power system after the doubly-fed wind turbine grid connection. The additional damping control method can play an important role in the friendly access of wind power, improve the level of wind energy consumption, and promote the development and utilization of new energy.

Those skilled in the art will appreciate 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 code.

The present invention is described with reference to the flowchart and/or block diagram of the method, device (system), and computer program product according to the embodiment of the present invention. It should be understood that each process and/or box in the flowchart and/or block diagram, as well as the combination of the process and/or box 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 produce a device for implementing the functions specified in one or more processes in the flowchart and/or one or more boxes in the block diagram.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device that implements the functions specified in one or more processes in the flowchart and/or one or more boxes in the block diagram.

These computer program instructions may also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and/or one or more boxes in the block diagram.

The invention has been described above with reference to a few embodiments. However, it is known 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.

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 // the [means, component, etc.]" are to be openly interpreted as at least one instance of a means, component, 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 (6)

1. An additional damping control method for a doubly-fed wind generator, comprising:

Generating a dq-axis inner loop current reference value; the actually measured dq axis current component passes through a blocking link and a gain link to generate an additional part of the dq axis inner loop current reference value;

the step of generating an additional part of the dq-axis inner loop current reference value by passing the actually measured dq-axis current component through a blocking link and a gain link, comprising:

the actually measured d-axis current component passes through a d-axis blocking link and a d-axis gain link to generate an additional part of a d-axis inner ring current reference value;

The actually measured q-axis current component passes through a q-axis blocking link and a q-axis gain link to generate an additional part of a q-axis inner loop current reference value;

adding the dq-axis inner loop current reference value and the additional part of the dq-axis inner loop current reference value to generate a dq-axis inner loop output current reference value;

The adding the dq-axis inner loop current reference value and the additional part of the dq-axis inner loop current reference value to generate a dq-axis inner loop output current reference value includes:

adding the d-axis inner loop current reference value and the additional part of the d-axis inner loop current reference value, and generating a d-axis inner loop output current reference value through amplitude limiting control;

adding the q-axis inner loop current reference value and the additional part of the q-axis inner loop current reference value, and generating a q-axis inner loop output current reference value through amplitude limiting control;

Wherein, A current reference value is output for the d-axis inner loop,Is the d-axis inner loop current reference value,Is an additional part of the d-axis inner loop current reference value, I _d is the actually measured d-axis current, K is the gain coefficient, T _w is the blocking link time constant,Limiting the boundary for the d-axis reference value;

a current reference value is output for the q-axis inner loop, Is the q-axis inner loop current reference value,For the q-axis inner loop current reference

The additional part, iq, is the measured q-axis current,Clipping edges for the q-axis reference value; s represents a complex number; generating dq-axis excitation voltage reference waves according to the dq-axis inner ring output current reference value, the actually measured dq-axis current component and the actually measured rotor side current;

the generating dq-axis excitation voltage reference wave according to the dq-axis inner ring output current reference value, the actually measured output current and the actually measured rotor side current comprises the following steps:

the deviation of the d-axis inner ring output current reference value and the actually measured d-axis current component is subjected to PI control to generate a d-axis rotor side current reference value;

the deviation of the d-axis rotor side current reference value and the actually measured d-axis rotor side current is subjected to PI control, and a feedforward cross decoupling item generated according to the actually measured q-axis rotor side current is introduced to generate d-axis excitation voltage reference waves;

the deviation of the q-axis inner ring output current reference value and the actually measured q-axis current component is subjected to PI control to generate a q-axis rotor side current reference value;

The deviation of the q-axis rotor side current reference value and the actually measured q-axis rotor side current is subjected to PI control, and a feedforward cross decoupling item generated according to the actually measured d-axis rotor side current is introduced to generate a q-axis excitation voltage reference wave;

and generating exciting voltage reference waves under a three-phase static coordinate system according to the dq-axis exciting voltage reference waves, wherein the exciting voltage reference waves under the three-phase static coordinate system are used for generating PWM (pulse width modulation) signals, and the PWM signals are used for controlling power devices arranged on a machine side converter.

2. An additional damping control method for a doubly-fed wind generator according to claim 1, further comprising, prior to said generating a dq-axis inner loop current reference value:

Performing park transformation on the measured rotor side current to obtain a measured q-axis rotor side current and a measured d-axis rotor side current; performing park transformation on the actually measured output current to obtain an actually measured q-axis current component and an actually measured d-axis current component; the angle required by the park transformation is a power grid angle obtained by virtual phase locking calculation according to the power grid reference frequency.

3. An additional damping control method for a doubly-fed wind generator according to claim 2 wherein said generating a dq-axis inner loop current reference value includes:

Introducing the actually measured q-axis current component into a voltage difference adjustment link to generate difference adjustment output;

adding the difference adjustment output to the deviation between the actually measured alternating voltage and the reference voltage, and generating a q-axis inner loop current reference value through PI control:

Wherein V' _ac is the regulated voltage, V _ac is the measured alternating voltage, X _c is the current-voltage gain coefficient, and T is the current-voltage blocking link time constant;

K _Pv、K_Iv is the voltage-current PI control parameter, Is an ac voltage reference.

4. The additional damping control method for a doubly-fed wind generator according to claim 1, wherein said generating an excitation voltage reference wave in a three-phase stationary coordinate system from said dq-axis excitation voltage reference wave includes:

And performing inverse park transformation on the q-axis exciting voltage reference wave and the d-axis exciting voltage reference wave to generate exciting voltage reference waves under a three-phase static coordinate system, wherein the angle required by inverse park transformation is the deviation of the power grid angle and the rotor angle obtained by virtual phase locking calculation according to the power grid reference frequency.

5. An additional damping control method for a doubly-fed wind generator according to claim 1 wherein said generating a dq-axis inner loop current reference value includes:

generating an active reference value through PI control on the deviation of the measured frequency and the reference frequency; the deviation of the active reference value and the actually measured active value is subjected to PI control to generate a d-axis inner ring current reference value;

Wherein, P ^* is an active reference value, K _Pf is a frequency power PI control parameter, f is an actual measurement frequency, and f ^* is a reference frequency; k _PP、K_IP is the power current PI control parameter, and P is the actual measured active value.

6. An additional damping control apparatus for a doubly-fed wind generator, for implementing the additional damping control method for a doubly-fed wind generator as claimed in claim 1, comprising:

The inner loop current reference value generation module is used for generating a dq-axis inner loop current reference value;

The additional part generating module is used for generating an additional part of the dq-axis inner loop current reference value by passing the actually measured dq-axis current component through a blocking link and a gain link;

The output current reference value generation module is used for adding the dq-axis inner ring current reference value and the additional part of the dq-axis inner ring current reference value to generate a dq-axis inner ring output current reference value;

The excitation voltage reference wave generation module is used for generating a dq-axis excitation voltage reference wave according to the dq-axis inner ring output current reference value, the actual measurement dq-axis current component and the actual measurement rotor side current; and generating exciting voltage reference waves under a three-phase static coordinate system according to the dq-axis exciting voltage reference waves, wherein the exciting voltage reference waves under the three-phase static coordinate system are used for generating PWM (pulse width modulation) signals, and the PWM signals are used for controlling power devices arranged on a machine side converter.