CN116404705A - Reactive current optimal distribution method and system for doubly-fed fan stator and grid-side converter - Google Patents
Reactive current optimal distribution method and system for doubly-fed fan stator and grid-side converter Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/50—Controlling the sharing of the out-of-phase component
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
- H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
- H02J3/1842—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
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Abstract
The invention provides a method and a system for optimally distributing reactive current of a doubly-fed wind turbine stator and a grid-side converter, wherein the method comprises the steps of determining stator current constraint based on relevant parameters of a doubly-fed wind turbine generator, and determining stator d-axis current representation based on the stator current constraint; the method comprises the steps that based on the fact that the current output of a grid-side converter is limited by the overcurrent capacity of the grid-side converter, d-axis current representation of the grid-side converter is obtained; determining constraints of the d-axis currents of the stator and the grid-side current transformer based on the stator and the d-axis current representations of the grid-side current transformer; determining a control range of the d-axis current of the stator based on a coupling relation between the d-axis currents of the stator and the grid-side converter; the control range of the stator q-axis current is obtained by taking the capacity limitation of the reactive circulation and the stator and the grid-side converter as constraint; acquiring the stator q-axis current when the active supporting capacity of the doubly-fed fan is maximum in the control range of the stator q-axis current; and obtaining the q-axis current of the grid-side converter based on the obtained q-axis current of the stator.
Description
Technical Field
The disclosure belongs to the technical field of wind power, and particularly relates to a method and a system for optimally distributing reactive current of a doubly-fed wind turbine stator and a grid-side converter.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
As the duty ratio of the doubly-fed wind turbine generator in the power system is higher, the influence of the doubly-fed wind turbine generator on the stability of the power system is larger. At present, besides the conventional low-voltage ride through requirement, wind power grid connection guidelines all require that the wind turbine generator have the capability of outputting reactive power to support the grid voltage when the grid voltage is reduced. However, due to the limited capacity of the doubly-fed wind turbine converter, reactive support often results in insufficient capacity to maintain active power output, and therefore, the active power output of the doubly-fed wind turbine tends to drop when the grid voltage drops. The instantaneous drop of active power can generate larger transient torque on a transmission shaft of the wind turbine, so that the mechanical safety and the active recovery rate of the doubly-fed wind turbine after fault removal are affected, and the frequency stability of the system is further affected. In the low-voltage ride through process, if the active power output of the doubly-fed wind turbine can be maintained as much as possible, the method is beneficial to the mechanical safety in the doubly-fed wind turbine and the frequency stability of an electric power system.
The inventor finds that, as shown in fig. 1, the power of the doubly-fed wind turbine generator is transmitted to the power Grid through two paths of a stator and a Grid-side converter (GSC), and the distribution mode of reactive power between the stator and the Grid-side converter can affect the remaining active transmission capacity of the doubly-fed wind turbine generator. Since the stator capacity is greater than the GSC capacity, the current mainstream approach is to have the doubly fed wind turbine stator output reactive power preferentially. However, such reactive power distribution approaches do not actually maximize the converter capacity of the doubly-fed wind turbines, impairing the active power output capability thereof during low voltage ride through.
Disclosure of Invention
In order to solve the problems, the present disclosure provides a method and a system for optimally distributing reactive current of a doubly-fed wind turbine stator and a grid-side converter, where the method and the system reasonably distribute the magnitude relation between the doubly-fed wind turbine stator and the GSC reactive current, and can maintain the output capability of external active current to the greatest extent under the condition that the total output reactive current is unchanged.
According to a first aspect of the embodiments of the present disclosure, there is provided a method for optimally distributing reactive current between a doubly-fed wind turbine stator and a grid-side converter, including:
acquiring relevant parameters of the doubly-fed wind turbine;
determining a stator current constraint based on the obtained relevant parameters, and determining a stator d-axis current representation based on the stator current constraint;
the method comprises the steps that based on the fact that the current output of a grid-side converter is limited by the overcurrent capacity of the grid-side converter, d-axis current representation of the grid-side converter is obtained;
determining constraints of stator and grid-side current transformer d-axis currents based on the stator d-axis current representation and the grid-side current transformer d-axis current representation;
determining a control range of the d-axis current of the stator based on a coupling relation between the d-axis currents of the stator and the grid-side converter;
the control range of the stator q-axis current is obtained by taking the reactive circulation between the rotor-side converter and the grid-side converter and the capacity limitation of the stator and the grid-side converter as constraints;
in the control range of the stator q-axis current, the stator q-axis current when the active supporting capacity of the doubly-fed fan is maximum is obtained by changing the stator q-axis current; and obtaining the q-axis current of the grid-side converter based on the obtained q-axis current of the stator.
Further, the determining a stator current constraint based on the obtained relevant parameters, and determining a stator d-axis current representation based on the stator current constraint, specifically includes: and obtaining stator current constraint according to the constraint of the rotor current by the current amplitude of the rotor-side converter based on the relation between the active power and reactive power output by the stator of the doubly-fed wind turbine and the d-axis and q-axis currents of the rotor by utilizing the obtained related parameters.
Further, the constraint of d-axis currents of the stator and the grid-side converter is specifically expressed as:
wherein I is sd Is the d-axis current of the doubly-fed fan stator, I gd For the d-axis current of the grid-side converter, L m Is the stator inductance, L s For mutual inductance of stator and rotor, I rmax Maximum current allowed for rotor-side converter, I sq Is the q-axis current of the doubly-fed fan stator, U s For stator voltage, I gq For the q-axis current of the grid-side converter, I gmax Maximum current allowed for the grid-side converter.
Further, the control range of the stator d-axis current is specifically expressed as:
wherein s is the slip of the generator,
further, the stator q-axis current is obtained by changing the stator q-axis current when the active supporting capacity of the doubly-fed fan is maximum, specifically: calculation I gd_res And |s|I sd_res Equal doubly-fed wind turbine stator current I sq_tgt The method comprises the steps of carrying out a first treatment on the surface of the I is as follows sq_tgt And U s /L s The minimum of the two is taken as the stator q-axis current.
Further, the control range of the stator q-axis current is specifically shown as follows:
wherein I is q The total q-axis current is the total q-axis current of the doubly-fed fan stator and the grid-side current transformer.
Further, the related parameters include stator inductance, stator-rotor mutual inductance, stator voltage, maximum current allowed by the grid-side converter, and maximum current allowed by the rotor side.
According to a second aspect of the embodiments of the present disclosure, there is provided a doubly-fed wind turbine stator and grid-side converter reactive current optimal distribution system, including:
the data acquisition unit is used for acquiring relevant parameters of the doubly-fed wind turbine generator;
a stator active current determination unit for determining a stator current constraint based on the obtained relevant parameters and determining a stator d-axis current representation based on the stator current constraint;
the GSC active current determining unit is used for obtaining d-axis current representation of the grid-side converter based on the fact that the current output of the grid-side converter is limited by the overcurrent capacity of the grid-side converter;
an active current constraint determining unit for determining constraints of the stator and the grid-side current transformer d-axis currents based on the stator d-axis current representation and the grid-side current transformer d-axis current representation;
the stator active current range determining unit is used for determining the control range of the stator d-axis current based on the coupling relation between the stator and the d-axis current of the grid-side converter;
a stator reactive current range determining unit for obtaining a control range of the stator q-axis current with the removal of reactive current between the rotor-side converter and the grid-side converter and the capacity limitation of the stator and the grid-side converter as constraints;
the reactive current optimal distribution unit is used for obtaining the stator q-axis current when the active supporting capacity of the doubly-fed fan is maximum by changing the stator q-axis current in the control range of the stator q-axis current; and obtaining the q-axis current of the grid-side converter based on the obtained q-axis current of the stator.
According to a third aspect of the disclosed embodiments, an electronic device is provided, which includes a memory, a processor, and a computer program running on the memory, where the processor implements the method for optimally distributing reactive current between the doubly-fed fan stator and the grid-side converter when executing the program.
According to a fourth aspect of the embodiments of the present disclosure, there is provided a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the method of optimally distributing reactive current of a doubly fed wind turbine stator and a grid-side converter.
Compared with the prior art, the beneficial effects of the present disclosure are:
the invention provides a method and a system for optimally distributing reactive current of a doubly-fed wind turbine stator and a grid-side converter, wherein the scheme provides an optimal distribution strategy of reactive current between the stator and a GSC, and the output capability of external active current can be maintained to the greatest extent under the condition that the total output reactive current is unchanged by reasonably distributing the magnitude relation between the doubly-fed wind turbine stator and the GSC reactive current; according to the scheme, the electric and mechanical stress in the wind turbine generator can be effectively reduced, and meanwhile, the stability of supporting the frequency of the power system is effectively improved.
Additional aspects of the disclosure will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the disclosure.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate and explain the exemplary embodiments of the disclosure and together with the description serve to explain the disclosure, and do not constitute an undue limitation on the disclosure.
FIG. 1 is a schematic diagram of a doubly-fed wind turbine topology as described in the background of the disclosure;
fig. 2 (a) and 2 (b) are schematic diagrams of stator and GSC residual capacity variation trends described in embodiments of the present disclosure;
fig. 3 is a flowchart of a method for optimally distributing reactive current of a doubly-fed wind turbine stator and a grid-side converter according to an embodiment of the disclosure;
FIG. 4 (a) is a graphical representation of the d-axis and q-axis current output capabilities of a doubly-fed wind turbine at a 1.2p.u. rotational speed as described in the examples of the present disclosure;
FIG. 4 (b) is a graphical representation of the d-axis and q-axis current output capabilities of a doubly-fed wind turbine at 0.7p.u. rotational speed as described in the examples of the present disclosure;
FIG. 5 (a) is a schematic diagram of the multi-output active power with a reactive support factor of 1.5 according to an embodiment of the present disclosure;
FIG. 5 (b) is a schematic diagram of the multi-output active power with a reactive support factor of 2 according to an embodiment of the present disclosure;
fig. 6 is a comparative simulation diagram of an embodiment of the present disclosure.
Detailed Description
The disclosure is further described below with reference to the drawings and examples.
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments in accordance with the present disclosure. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
Embodiments of the present disclosure and features of embodiments may be combined with each other without conflict.
Embodiment one:
the aim of the embodiment is to provide an optimal distribution method of reactive current of a doubly-fed fan stator and a grid-side converter.
A reactive current optimal distribution method for a doubly-fed wind turbine stator and a grid-side converter comprises the following steps:
acquiring relevant parameters of the doubly-fed wind turbine;
determining a stator current constraint based on the obtained relevant parameters, and determining a stator d-axis current representation based on the stator current constraint;
the method comprises the steps that based on the fact that the current output of a grid-side converter is limited by the overcurrent capacity of the grid-side converter, d-axis current representation of the grid-side converter is obtained;
determining constraints of stator and grid-side current transformer d-axis currents based on the stator d-axis current representation and the grid-side current transformer d-axis current representation;
determining a control range of the d-axis current of the stator based on a coupling relation between the d-axis currents of the stator and the grid-side converter;
the control range of the stator q-axis current is obtained by taking the reactive circulation between the rotor-side converter and the grid-side converter and the capacity limitation of the stator and the grid-side converter as constraints;
in the control range of the stator q-axis current, the stator q-axis current when the active supporting capacity of the doubly-fed fan is maximum is obtained by changing the stator q-axis current; and obtaining the q-axis current of the grid-side converter based on the obtained q-axis current of the stator.
Further, the determining a stator current constraint based on the obtained relevant parameters, and determining a stator d-axis current representation based on the stator current constraint, specifically includes: and obtaining stator current constraint according to the constraint of the rotor current by the current amplitude of the rotor-side converter based on the relation between the active power and reactive power output by the stator of the doubly-fed wind turbine and the d-axis and q-axis currents of the rotor by utilizing the obtained related parameters.
Further, the constraint of d-axis currents of the stator and the grid-side converter is specifically expressed as:
wherein I is sd Is the d-axis current of the doubly-fed fan stator, I gd For the d-axis current of the grid-side converter, L m Is the stator inductance, L s For mutual inductance of stator and rotor, I rmax Maximum current allowed for rotor-side converter, I sq Is the q-axis current of the doubly-fed fan stator, U s For stator voltage, I gq For the q-axis current of the grid-side converter, I gmax Maximum current allowed for the grid-side converter.
Further, the control range of the stator d-axis current is specifically expressed as:
wherein s is the slip of the generator,
further, the stator q-axis current is obtained by changing the stator q-axis current when the active supporting capacity of the doubly-fed fan is maximum, specifically: calculation I gd_res And |s|I sd_res Equal doubly-fed wind turbine stator current I sq_tgt The method comprises the steps of carrying out a first treatment on the surface of the I is as follows sq_tgt And U s /L s The minimum of the two is taken as the stator q-axis current.
Further, the control range of the stator q-axis current is specifically shown as follows:
wherein I is q The total q-axis current is the total q-axis current of the doubly-fed fan stator and the grid-side current transformer.
Further, the related parameters include stator inductance, stator-rotor mutual inductance, stator voltage, maximum current allowed by the grid-side converter, and maximum current allowed by the rotor side.
In particular, for easy understanding, the following detailed description of the embodiments will be given with reference to the accompanying drawings:
for a doubly-fed wind turbine stator, if stator voltage orientation is adopted, the relation between active power and reactive power output by the stator and dq-axis current of the rotor is respectively as follows:
wherein P is s And Q s Active power and reactive power output by the stator respectively, L m And L s Respectively representing the inductance of the stator and the mutual inductance of the stator and the rotor, U s Representing stator voltage, I rd And I rq Representing rotor dq-axis current, ω 1 Represents the system frequency, typically 50 x 2 pi rad/s.
The dq-axis currents of the stator can be expressed as:
wherein I is sd And I sq Representing stator dq axis current.
The formula (2) can be obtained after per unit (hereinafter, the term "per unit" is omitted)
For rotor currents, constrained by rotor-side converter (RSC) current amplitudes, it is necessary to satisfy the following constraints:
wherein I is rmax Is the maximum current allowed by the RSC.
Converting equation (4) into stator current constraints yields:
reactive current of stator is I sq The remaining d-axis current capacity is:
and for GSCs, the current output is also limited by the GSC current-carrying capability. Let the reactive support of GSC be I gq The GSC residual active current capacity is then:
wherein I is gmax Is the maximum current allowed by the GSC.
By assuming the total q-axis current of the stator and GSC to be I q The q-axis current of the stator is I sq Then the q-axis current of GSC is I gq ＝I q -I sq . To prevent current out-of-limit, the d-axis currents of the stator and the GSC should be controlled at this time:
for a doubly-fed wind turbine, the stator of the doubly-fed wind turbine has a coupling relation with active current of GSC, which is that
I gd ＝-sI sd (9)
Substituting formula (9) into formula (8) to obtain:
as shown in formula (8), the reactive power distribution between the stator and the GSC varies I sd_res And I gd_res And thus the active output capacity of the doubly fed wind machine. In order to ensure the active supporting capacity of the doubly-fed wind turbine as much as possible, the allocation of reactive supporting amounts of the stator and the GSC needs to be reasonably set.
Firstly, in order to make effective use of the capacity of the converter, it is obvious that reactive power distribution should be avoidedReactive circulation between RSC-free and GSC (reactive power circulation), i.e. I sq The values of (2) should be:
second, consider the capacity constraints of the stator and GSC, I sq The values of (a) are respectively as follows:
I sqmin ≤I sq ≤I sqmax (12)
I q -I gmax ≤I sq ≤I q +I gmax (13)
the general formula (11), the general formula (12) and the general formula (13), I sq The range of the values is as follows:
within this range, change I sq ，|s|I sd_res And I gd_res The change trend of (a) is shown in fig. 2 (a) and 2 (b). When I sq When the minimum value is obtained (I q Or I sqmin ) Meaning that the stator is given priority to output reactive current, in which case there must be I gd_res >|s|I sd_res This is because the doubly-fed wind generator GSC needs to ensure that it has sufficient capacity to deliver power transmitted via the RSC and dc bus into the grid when selecting the type. Following I sq Enlargement, I gd_res Monotonically decrease and |s|I sd_res Monotonically increasing. When the two values are equal, the active supporting capacity is the largest, and at this time, there is:
I gd_res ＝|s|I sd_res (15)
the corresponding stator current at this time can be calculated according to equation (15) as:
wherein the method comprises the steps of
In addition to this, there is another case where the two curves do not have an intersection point in this range, as shown in fig. 2 (b). The active supporting capacity of the doubly-fed wind machine is represented by the following curve I sd_res It is decided that the point to maximize, i.e. the right end point, should be selected, at which point I sq ＝U s /L s 。
In summary, the optimal reactive power of the stator and GSC is:
specifically, in order to prove the effectiveness of the scheme described in this embodiment, a corresponding comparative experiment was performed in this embodiment:
compared with the traditional control mode of preferentially utilizing the stator to output reactive current, the optimal distribution strategy of reactive current between the stator and the GSC can maximize the active current output capacity of the doubly-fed fan. Under the electrical parameters of the doubly-fed wind turbine generator set shown in table 1, the dq-axis current output capacity of the doubly-fed wind turbine generator set brought by optimal reactive power distribution is expanded as shown in fig. 4 and 5. It can be seen that the proposed control scheme makes more efficient use of the capacity of the doubly fed wind turbine converter than the control scheme that uses stator support reactive preferentially.
Table 1 electrical parameters of doubly fed fans
Wind turbines typically employ reactive current-voltage sag control to support reactive current to the grid. Typical control means are
I q ＝max(-k q (0.9-U s ),I qmin ) (19)
Wherein the method comprises the steps of
When the reactive support coefficient k q When 1.5 and 2 are taken respectively, the active power which can be outputted by the doubly-fed fan after the stator and the GSC are optimally distributed is shown in the figure 5 (a) and the figure 5 (b) respectively. It can be seen that after the optimal allocation is adopted, the active power output of the doubly fed fan can be increased by about 0.1p.u. to 0.4p.u. and the time required for active recovery can be reduced in proportion to the active drop degree at the same active recovery rate. This means that the energy deficit generated by the active recovery process can be reduced by 19% as long as the active power drop is reduced by 10%.
The optimal distribution (Scheme 2) between the stator and the GSC is provided by taking the stator output reactive power (Scheme 1) as a comparison object, so that the active power output capacity of the doubly-fed wind turbine generator during low-voltage ride through can be obviously improved. As shown in fig. 6, the doubly-fed wind turbine generator is able to maintain more active power output during the duration of the fault, which also helps it to recover active power faster after the fault clears.
Embodiment two:
the aim of the embodiment is to provide an optimal reactive current distribution system for a doubly-fed fan stator and a grid-side converter.
An optimal distribution system for reactive current of a doubly-fed wind turbine stator and a grid-side converter, comprising:
the data acquisition unit is used for acquiring relevant parameters of the doubly-fed wind turbine generator;
a stator active current determination unit for determining a stator current constraint based on the obtained relevant parameters and determining a stator d-axis current representation based on the stator current constraint;
the GSC active current determining unit is used for obtaining d-axis current representation of the grid-side converter based on the fact that the current output of the grid-side converter is limited by the overcurrent capacity of the grid-side converter;
an active current constraint determining unit for determining constraints of the stator and the grid-side current transformer d-axis currents based on the stator d-axis current representation and the grid-side current transformer d-axis current representation;
the stator active current range determining unit is used for determining the control range of the stator d-axis current based on the coupling relation between the stator and the d-axis current of the grid-side converter;
a stator reactive current range determining unit for obtaining a control range of the stator q-axis current with the removal of reactive current between the rotor-side converter and the grid-side converter and the capacity limitation of the stator and the grid-side converter as constraints;
the reactive current optimal distribution unit is used for obtaining the stator q-axis current when the active supporting capacity of the doubly-fed fan is maximum by changing the stator q-axis current in the control range of the stator q-axis current; and obtaining the q-axis current of the grid-side converter based on the obtained q-axis current of the stator.
Further, the system in this embodiment corresponds to the method in the first embodiment, and the technical details thereof are described in the first embodiment, so that they will not be described herein.
In further embodiments, there is also provided:
an electronic device comprising a memory and a processor and computer instructions stored on the memory and running on the processor, which when executed by the processor, perform the method of embodiment one. For brevity, the description is omitted here.
It should be understood that in this embodiment, the processor may be a central processing unit CPU, and the processor may also be other general purpose processors, digital signal processors DSP, application specific integrated circuits ASIC, off-the-shelf programmable gate array FPGA or other programmable logic device, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory may include read only memory and random access memory and provide instructions and data to the processor, and a portion of the memory may also include non-volatile random access memory. For example, the memory may also store information of the device type.
A computer readable storage medium storing computer instructions which, when executed by a processor, perform the method of embodiment one.
The method in the first embodiment may be directly implemented as a hardware processor executing or implemented by a combination of hardware and software modules in the processor. The software modules may be located in a random access memory, flash memory, read only memory, programmable read only memory, or electrically erasable programmable memory, registers, etc. as well known in the art. The storage medium is located in a memory, and the processor reads the information in the memory and, in combination with its hardware, performs the steps of the above method. To avoid repetition, a detailed description is not provided herein.
Those of ordinary skill in the art will appreciate that the elements of the various examples described in connection with the present embodiments, i.e., the algorithm steps, can be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.
The method and the system for optimally distributing the reactive current of the doubly-fed fan stator and the network side converter can be realized, and have wide application prospects.
The foregoing description of the preferred embodiments of the present disclosure is provided only and not intended to limit the disclosure so that various modifications and changes may be made to the present disclosure by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
Claims (10)
1. The method for optimally distributing reactive current of the doubly-fed wind turbine stator and the grid-side converter is characterized by comprising the following steps of:
acquiring relevant parameters of the doubly-fed wind turbine; determining a stator current constraint based on the obtained relevant parameters, and determining a stator d-axis current representation based on the stator current constraint;
the method comprises the steps that based on the fact that the current output of a grid-side converter is limited by the overcurrent capacity of the grid-side converter, d-axis current representation of the grid-side converter is obtained;
determining constraints of stator and grid-side current transformer d-axis currents based on the stator d-axis current representation and the grid-side current transformer d-axis current representation;
determining a control range of the d-axis current of the stator based on a coupling relation between the d-axis currents of the stator and the grid-side converter;
the control range of the stator q-axis current is obtained by taking the reactive circulation between the rotor-side converter and the grid-side converter and the capacity limitation of the stator and the grid-side converter as constraints;
in the control range of the stator q-axis current, the stator q-axis current when the active supporting capacity of the doubly-fed fan is maximum is obtained by changing the stator q-axis current; and obtaining the q-axis current of the grid-side converter based on the obtained q-axis current of the stator.
2. The method for optimally distributing reactive current between a doubly-fed wind turbine stator and a grid-side converter according to claim 1, wherein the determining a stator current constraint based on the obtained related parameters and determining a stator d-axis current representation based on the stator current constraint comprises: and obtaining stator current constraint according to the constraint of the rotor current by the current amplitude of the rotor-side converter based on the relation between the active power and reactive power output by the stator of the doubly-fed wind turbine and the d-axis and q-axis currents of the rotor by utilizing the obtained related parameters.
3. The method for optimally distributing reactive current of a doubly-fed wind turbine stator and a grid-side converter according to claim 1, wherein the constraint of d-axis current of the stator and the grid-side converter is specifically expressed as follows:
wherein I is sd Is the d-axis current of the doubly-fed fan stator, I gd For the d-axis current of the grid-side converter, L m Is the stator inductance, L s For mutual inductance of stator and rotor, I rmax Maximum current allowed for rotor-side converter, I sq Is the q-axis current of the doubly-fed fan stator, U s For stator voltage, I gq For the q-axis current of the grid-side converter, I gmax Maximum current allowed for the grid-side converter.
4. The method for optimally distributing reactive current of a doubly-fed wind turbine stator and a grid-side converter according to claim 1, wherein the control range of the d-axis current of the stator is specifically shown as follows:
wherein s is the slip of the generator,
5. the method for optimally distributing reactive current between a doubly-fed wind turbine stator and a grid-side converter according to claim 1, wherein the method is characterized in that the stator q-axis current is obtained by changing the stator q-axis current when the doubly-fed wind turbine active supporting capability is maximum, specifically: calculation I gd_res And sI sd_res Equal doubly-fed wind turbine stator current I sq_tgt The method comprises the steps of carrying out a first treatment on the surface of the I is as follows sq_tgt And U s /L s The minimum of the two is taken as the stator q-axis current.
6. The method for optimally distributing reactive current of a doubly-fed wind turbine stator and a grid-side converter according to claim 1, wherein the control range of the stator q-axis current is specifically as follows:
wherein I is q The total q-axis current is the total q-axis current of the doubly-fed fan stator and the grid-side current transformer.
7. The method for optimally distributing reactive current between a doubly-fed machine stator and a grid-side converter according to claim 1 wherein said related parameters include stator inductance, stator-rotor mutual inductance, stator voltage, maximum current allowed by the grid-side converter and maximum current allowed by the rotor-side.
8. An optimal distribution system for reactive current of a doubly-fed wind turbine stator and a grid-side converter is characterized by comprising:
the data acquisition unit is used for acquiring relevant parameters of the doubly-fed wind turbine generator;
a stator active current determination unit for determining a stator current constraint based on the obtained relevant parameters and determining a stator d-axis current representation based on the stator current constraint;
the GSC active current determining unit is used for obtaining d-axis current representation of the grid-side converter based on the fact that the current output of the grid-side converter is limited by the overcurrent capacity of the grid-side converter;
an active current constraint determining unit for determining constraints of the stator and the grid-side current transformer d-axis currents based on the stator d-axis current representation and the grid-side current transformer d-axis current representation;
the stator active current range determining unit is used for determining the control range of the stator d-axis current based on the coupling relation between the stator and the d-axis current of the grid-side converter;
a stator reactive current range determining unit for obtaining a control range of the stator q-axis current with the removal of reactive current between the rotor-side converter and the grid-side converter and the capacity limitation of the stator and the grid-side converter as constraints;
the reactive current optimal distribution unit is used for obtaining the stator q-axis current when the active supporting capacity of the doubly-fed fan is maximum by changing the stator q-axis current in the control range of the stator q-axis current; and obtaining the q-axis current of the grid-side converter based on the obtained q-axis current of the stator.
9. An electronic device comprising a memory, a processor and a computer program stored for running on the memory, wherein the processor implements a method for optimally distributing reactive current between a doubly fed fan stator and a grid-side converter according to any one of claims 1-7 when executing the program.
10. A non-transitory computer readable storage medium having stored thereon a computer program, which when executed by a processor, implements a method of optimally distributing reactive current for a doubly fed wind turbine stator and a grid side converter according to any one of claims 1-7.
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