CN116131368A - Control method suitable for maximum active power output during low voltage ride through of doubly-fed wind farm - Google Patents

Control method suitable for maximum active power output during low voltage ride through of doubly-fed wind farm Download PDF

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CN116131368A
CN116131368A CN202310208365.2A CN202310208365A CN116131368A CN 116131368 A CN116131368 A CN 116131368A CN 202310208365 A CN202310208365 A CN 202310208365A CN 116131368 A CN116131368 A CN 116131368A
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current
reactive
rotor
dfig
grid
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李博通
郑丁川
李斌
陈晓龙
焦新茹
李佳宁
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Tianjin University
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Tianjin University
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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
    • H02J3/48—Controlling the sharing of the in-phase component
    • 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
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • 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
    • H02J3/381—Dispersed generators
    • 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
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/76—Power conversion electric or electronic aspects

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  • Control Of Eletrric Generators (AREA)

Abstract

The invention relates to a control method suitable for maximum active power output during low voltage ride through of a doubly-fed wind farm, which comprises the following steps: s1, determining the injection requirement of reactive current during low-voltage ride through of a wind power plant; s2, determining a reactive current output mode according to whether a reactive compensation device is configured in the wind farm or not; s3, d-axis current i of rotor-side converter rd_LVRT Optimizing a reference value; s4, d-axis current i of grid-side converter gd_LVRT And optimizing a reference value. The reactive current distribution strategy provided by the invention comprehensively considers whether the current wind power plant is provided with a reactive compensation device, so that the doubly-fed wind power plant has the capability of outputting more active power on the basis of meeting the national standard GB/T19963.1-2021 reactive current support, can slow down the rising rate of the rotating speed of a rotor, reduces the power loss of a power grid and prolongs the service lifeAnd the low voltage ride through operation time improves the low voltage ride through operation capability of the wind power plant.

Description

Control method suitable for maximum active power output during low voltage ride through of doubly-fed wind farm
Technical Field
The invention belongs to the technical field of wind power systems of electrical technology, and particularly relates to a control method suitable for maximum active power output during low-voltage ride through of a doubly-fed wind power plant.
Background
The doubly-fed wind turbine is one of main stream wind turbines of the land wind power plant in China, the converter capacity of the doubly-fed wind turbine is only 30% of the rated capacity of the generator, and the doubly-fed wind turbine is low in manufacturing cost and good in economical efficiency. However, the doubly-fed wind turbine stator is directly connected with a power grid, is very sensitive to the voltage drop of the power grid, and generates a larger transient component due to the stator flux linkage when an external power grid fails, and serious overvoltage and overcurrent are generated on the rotor side of the DFIG under the influence of the larger transient component. If no protective measures are taken, the serious consequences of converter damage and grid disconnection of the wind turbine generator can be caused, and the safe and stable operation of the power system is directly affected. The latest GB/T19963.1-2021 standard in China requires that a wind power plant has low voltage ride through capability, namely that a wind turbine generator can keep continuous operation without off-grid for a period of time during voltage sag, and reactive current is injected into a power grid during the period of time to support power grid voltage recovery.
The existing low voltage ride through protection of the doubly-fed wind power plant mainly comprises the following scheme:
1: traditional crow bar protection scheme: the crowbar protection circuit is put into operation when the voltage of the grid-connected point drops, and is cut off after the fault is cleared. According to the scheme, the internal electric quantity of the fan can be maintained to be not out of limit so as to complete fault ride-through, but the current transformer cannot effectively control the doubly-fed fan during the crowbar protection input period, the doubly-fed fan is in an asynchronous running state, a large amount of reactive power is absorbed from a power grid, and the voltage drop degree is further increased.
2: the grid-side converter provides a reactive support scheme: this solution provides reactive support to the grid with the grid-side converter during crowbar protection inputs, however the grid-side converter has a smaller capacity, which cannot meet the reactive demand in a scenario with a larger voltage drop depth.
3: the stator provides a reactive support solution: according to the scheme, after the crowbar protection is put into 40ms, a crowbar circuit is cut off, a rotor side converter is restarted, a stator is controlled to provide reactive current support for a power grid through switching a rotor side converter current loop reference value, and the reactive current support capability of a doubly-fed fan is not fully utilized in the mode, so that the active output capability of the fan is weaker during low-voltage ride through.
4: the reactive compensation device provides a reactive support scheme: the reactive power compensation device injects reactive current into a power grid, and the voltage of a doubly-fed wind turbine terminal is raised to improve the low-voltage ride-through capability of a wind power plant. However, the scheme does not utilize the reactive power output capability of the wind turbine generator, and the required reactive power compensation device has larger capacity and higher cost.
In summary, the low-voltage ride through scheme of the doubly-fed wind power plant basically only depends on a fan per se or only depends on a reactive power compensation device to provide reactive current support, and reactive power output optimization matching schemes of a fan stator, a grid-side converter and the reactive power compensation device are not researched.
Meanwhile, the active current scheme has not been considered yet in the present low voltage ride through scheme. In fact, during low voltage ride through, if the wind farm output active current is zero, it may cause the power system with smaller inertia to generate a larger active deficiency to decrease the system frequency, and in serious cases, it may cause the low frequency load shedding device to act and even cause serious consequences of system frequency breakdown. In addition, during low voltage ride through, the fan input mechanical power can be approximately considered unchanged, the doubly fed fan output electromagnetic power is reduced, the rotor rotation speed can be increased due to power imbalance, and the fan overspeed protection can be triggered, so that the fan is off-grid.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides a control method suitable for the maximum active power output of a doubly-fed wind power plant in the low voltage ride through period, can realize the reactive power requirement and the maximum active power output of the doubly-fed wind power plant in the low voltage ride through period, and prolongs the low voltage ride through operation time.
The invention solves the technical problems by the following technical proposal:
the control method for the maximum active power output during the low voltage ride through of the doubly-fed wind farm is characterized by comprising the following steps of: the method comprises the following steps:
s1, combining a doubly-fed wind power system and a doubly-fed wind power converter, and determining the injection requirement on reactive current when a wind power plant passes through at low voltage, wherein the injection requirement is as shown in the formula (1):
ΔI q ＝K×(0.9-U pcc )×I N ,(0.2≤U pcc ≤0.9) (1)
wherein: ΔI q Reactive current injection amount specified for the standard;
k is a reactive compensation coefficient;
U pcc the voltage per unit value is the grid-connected point voltage per unit value;
I N rated current for the wind farm;
s2, determining a reactive current output mode according to whether a reactive compensation device is configured in the wind farm:
for a wind farm provided with a reactive compensation device, the reactive compensation device is preferentially utilized to output reactive current during low-voltage ride through, and when the reactive compensation device does not output reactive current to meet the requirement, the DFIG is utilized to output reactive current, so that the reactive current I output by the DFIG is required during the low-voltage ride through Q The method comprises the following steps:
Figure BDA0004111671590000021
wherein: i Q Reactive current required to be output for DFIG;
k is a reactive compensation coefficient;
U pcc the voltage per unit value of the grid-connected point power grid in the low-voltage crossing period;
for wind farms not equipped with reactive compensation devices, the reactive current is provided by the DFIG itself, and therefore
I Q ＝K(0.9-U pcc ) (3)
Wherein: i Q Reactive current required to be output for DFIG;
k is a reactive compensation coefficient;
U pcc is of low pressureGrid voltage per unit value of the grid connection point during the crossing period;
DFIG output total active power P during low voltage ride through DFIG With rotor current i rd The following relationship exists:
Figure BDA0004111671590000031
wherein: p (P) DFIG Active power output by the DFIG;
s is slip;
i rd d-axis current of the rotor converter;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
L s is a stator inductance;
as is clear from (4), when the rotor-side current transformer d-axis current i rd At maximum, the DFIG outputs the total active power P DFIG Reaching the maximum;
s3, d-axis current i of rotor-side converter rd Reference value optimization
At rotor current I rmax Constrained rotor d-axis current i rd And q-axis current i rq There is a constraint represented by formula (5):
Figure BDA0004111671590000032
wherein: i rmax Maximum current allowed to pass when the rotor converter is safely operated;
i rd d-axis current of the rotor converter;
i rq q-axis current for the rotor converter;
as can be seen from (5), the d-axis current i of the rotor-side current transformer is to be set rd Maximum rotor q-axis current modulus value i rq I should be as small as possible on a satisfactory basis,
the reactive current of the DFIG during low voltage ride through is provided by the grid side converter and the DFIG stator together, namely:
I Q ＝i gq +i sq (6)
wherein: i Q Reactive current required to be output for DFIG;
i gq reactive current provided to the grid-side converter;
i sq reactive current provided to the DFIG stator;
DFIG stator output reactive power Q s Reactive current i with stator sq And rotor q-axis current i rq There is a relationship of formula (7):
Figure BDA0004111671590000041
wherein: q (Q) s Reactive power output for the DFIG stator;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
L s is a stator inductance;
ω s is the voltage electrical angular frequency;
i sq is stator q-axis current;
i rq q-axis current for the rotor;
from equation (7), i can be calculated sq And i rq As shown in the formula (8):
Figure BDA0004111671590000042
wherein: i.e sq Is stator q-axis current;
L s is a stator inductance;
ω s is the voltage electrical angular frequency;
i rq q-axis current for the rotor converter;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
as can be seen from (8), only when the rotor q-axis current i rq If the voltage is less than 0, the DFIG stator can output reactive current (i sq Greater than 0), and rotor q-axis current modulus value i rq The larger the I is, the stator outputs reactive current i sq The larger. As can be seen from (7) and (8), the rotor q-axis current modulus value i is to be set rq As small as possible, the grid-side converter should be used to output reactive current preferentially, and then the DFIG stator should be used to output reactive current;
s4, d-axis current i of grid-side converter gd_LVRT Reference value optimization
The control target of the grid-side converter is that the direct-current side voltage is stable, and the d-axis current reference value i of the grid-side converter during the low-voltage ride-through period gd_LVRT Obtained from the voltage outer loop, priority guarantees are required:
i gd_LVRT ＝i gdref (9)
wherein: i.e gd_LVRT The current reference value is the d-axis current reference value of the grid-side converter;
i gdref an active current reference value obtained for a voltage loop of the grid-side converter;
to ensure that the DFIG can output more active power, the network-side converter should be preferentially utilized to output reactive current during the low voltage ride through period, and the q-axis current reference value i thereof gq_LVRT The method comprises the following steps:
Figure BDA0004111671590000051
wherein: i.e gq_LVRT The current reference value is the q-axis current reference value of the grid-side converter;
I gmax maximum current allowed to pass for a grid-side converter, typically I gmax 0.3pu;
i gdref an active current reference value obtained for a voltage loop of the grid-side converter;
I Q reactive current required to be output for DFIG;
when the reactive current output capability of the network-side converter can meet the reactive current requirement of the system, namely
Figure BDA0004111671590000052
In this case, only the network-side converter outputs reactive current, without the DFIG stator outputting reactive current, i sq 0, according to equation (8), rotor-side converter current loop q-axis reference i rq_LVRT The method comprises the following steps:
Figure BDA0004111671590000053
wherein: i.e rq_LVRT A q-axis current reference value of the rotor-side converter;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
ω s is the voltage electrical angular frequency;
on the premise of meeting reactive power requirements of a power system, in order to ensure that the wind turbine can output active power as much as possible, a d-axis reference value i of a rotor-side converter rd_LVRT The method comprises the following steps:
Figure BDA0004111671590000054
wherein: i.e rd_LVRT The reference value is the d-axis current of the rotor-side converter;
i rq_LVRT a q-axis current reference value of the rotor-side converter;
I rmax maximum current allowed to pass for rotor-side converters, typically I rmax 1.2pu;
i rdref the active current reference value is obtained by maximum power tracking control;
when the reactive current output capability of the network-side converter cannot meet the reactive current requirement of the system, namely
Figure BDA0004111671590000055
At this time, the DFIG stator is also required to output reactive current. To ensure reactive current output preferentially, according to equation (8), the rotor-side converter current loop q-axis reference i rq_LVRT The method comprises the following steps:
Figure BDA0004111671590000056
wherein: i.e rq_LVRT A q-axis current reference value of the rotor-side converter;
i gq_LVRT the current reference value is the q-axis current reference value of the grid-side converter;
I Q reactive current required to be output for DFIG;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
L s is a stator inductance;
ω s is the voltage electrical angular frequency;
on the premise of meeting reactive power requirements of the system, in order to ensure that the wind turbine can output maximum active power, a d-axis reference value i of the rotor-side converter rd_LVRT Still given by equation (13).
The invention has the advantages and beneficial effects that:
compared with the prior art, the method is suitable for controlling the maximum active power output during the low voltage ride through of the doubly-fed wind power plant, the reactive current distribution strategy is provided, whether the current wind power plant is provided with a reactive compensation device is comprehensively considered, so that the doubly-fed wind power plant has the capability of outputting more active power on the basis of meeting the national standard GB/T19963.1-2021 reactive current support, the rising rate of the rotating speed of a rotor can be slowed down, the power loss of a power grid is reduced, the low voltage ride through operation time is prolonged, and the low voltage ride through operation capability of the wind power plant is improved.
Drawings
FIG. 1 is a schematic diagram of a doubly-fed wind power system according to the present invention;
FIG. 2 is a control block diagram of a doubly-fed wind power system converter according to the present invention;
FIG. 3 is a schematic diagram illustrating the basic requirements of the low voltage ride through according to the present invention;
FIG. 4 is a schematic diagram of reactive current distribution strategy of a wind farm equipped with reactive compensation devices according to the present invention;
fig. 5 is a schematic diagram of reactive current distribution strategy of a wind farm without reactive compensation device according to the present invention.
Detailed Description
The invention is further illustrated by the following examples, which are intended to be illustrative only and not limiting in any way.
FIG. 1 shows the basic structure of the doubly-fed wind power system of the present invention. The doubly-fed wind power plant mainly comprises a wind turbine, a doubly-fed motor, a grid-side converter and a rotor-side converter. The crow bar protection circuit is arranged on the alternating current side of the rotor side converter; the direct current side is provided with a chopper protection circuit; the reactive power compensation device is STATCOM in the figure.
Fig. 2 shows a vector control block diagram commonly used in doubly fed fan converter engineering. D-axis control target of grid-side converter is direct-current voltage U dc The Q-axis control target is the reactive power Q of the grid-side converter g The method comprises the steps of carrying out a first treatment on the surface of the The d-axis control target of the rotor-side converter is stator active power P s The reference value is obtained by tracking the maximum wind energy, and the Q-axis control target is the output reactive power Q of the stator s . When the voltage drops, the control system current loop switches the reference value according to the content of the invention to realize low voltage ride through.
In FIG. 2, P ref For the active power reference value, P is the active power, i rdmax For the upper limit of the current of the rotor d-axis, i rdmin For the lower limit of the d axis of the rotor, i rdref I is the current reference value of the rotor d-axis rd_LVRT Is the reference value of the d axis of the rotor during the low voltage crossing period, i rd For rotor d-axis current, ω slip For the slip angular frequency, σ is the leakage inductance, L r I is the rotor inductance rq For rotor q-axis current, L s Is the stator inductance, L m U is the excitation inductance sd R is the d-axis component of the stator voltage s Is the stator resistance, i sd For the d-axis component, ω, of the stator current r For rotor speed, omega s For voltage electric angular velocity, ψ sq Representing the q-axis component of the stator flux linkage, v rdmin For the lower voltage limit of the rotor d-axis, v rdmax For the upper limit of the d-axis voltage of the rotor, u rdref For the d-axis reference value of the rotor voltageQ represents reactive power, Q ref I is the reactive power reference value rqmax For the upper limit of the rotor q-axis current, i rqmin For the lower current limit of the rotor q-axis, i rqref For rotor q-axis current reference value, i rq_LVRT Is the reference value of the q axis of the rotor during the low voltage crossing period, ψ sd Representing the d-axis component, v, of the stator flux linkage rqmin For the lower voltage limit of the rotor q-axis, v rqmax For the upper limit of the rotor q-axis voltage, u rqref For the rotor voltage q-axis reference value, U dcref U is the direct current voltage reference value of the network side converter dc Is a direct current voltage, i gqmax For the upper limit of q-axis current of the grid-side converter, i gqmin The lower limit of q-axis current of the grid-side converter, i gqref For the q-axis current reference value, i of the grid-side converter gq_LVRT Is the q-axis current reference value, i of the grid-side converter during the low voltage ride through period gq For the q-axis current of the grid-side converter, u gd For the d-axis voltage of the grid-side converter, L g V is the inductance of the AC side of the network side converter gqmin V is the lower limit of q-axis voltage of the grid-side converter gqmax For the upper limit of the q-axis voltage of the grid-side converter, u gqref For the q-axis reference value, i of the voltage of the grid-side converter gdmax The upper limit of d-axis current of the grid-side converter, i gdmin The current lower limit of the d-axis current of the grid-side converter, i gdref I is the current reference value of the d axis of the grid-side converter gd_LVRT Is the d-axis current reference value, i of the grid-side converter during the low voltage ride through period gd For the d-axis current of the grid-side converter, u gq For the q-axis voltage of the grid-side converter, v gdmin V is the lower limit of d-axis voltage of the grid-side converter gdmax For the upper limit of d-axis voltage of the grid-side converter, u gdref Is the d-axis reference value of the voltage of the grid-side converter.
Fig. 3 illustrates the national standard requirements for low voltage ride through time of a wind farm during low voltage ride through.
The invention discloses a control method suitable for maximum active power output during low voltage ride through of a doubly-fed wind farm, which is characterized by comprising the following steps of: the method comprises the following steps:
s1, combining a doubly-fed wind power system and a doubly-fed wind power converter, and determining the injection requirement on reactive current when a wind power plant passes through at low voltage, wherein the injection requirement is as shown in the formula (1):
ΔI q ＝K×(0.9-U pcc )×I N ,(0.2≤U pcc ≤0.9) (1)
wherein: ΔI q Reactive current injection amount specified for the standard;
k is a reactive compensation coefficient (K is more than or equal to 1.5 and less than or equal to 3);
U pcc the voltage per unit value is the grid-connected point voltage per unit value;
I N rated current for the wind farm;
s2, determining a reactive current output mode according to whether a reactive compensation device is configured in the wind farm:
taking STATCOM output rated current 1pu as an example, optimizing a reference value in a low voltage ride through period according to whether a wind field is provided with a reactive power compensation device or not;
for a wind farm provided with a reactive compensation device, the reactive compensation device is preferentially utilized to output reactive current during low-voltage ride through, and when the reactive compensation device does not output reactive current to meet the requirement, the DFIG is utilized to output reactive current, so that the reactive current I output by the DFIG is required during the low-voltage ride through Q The method comprises the following steps:
Figure BDA0004111671590000081
wherein: i Q Reactive current required to be output for DFIG;
k is a reactive compensation coefficient;
U pcc the voltage per unit value of the grid-connected point power grid in the low-voltage crossing period;
for wind farms not equipped with reactive compensation devices, the reactive current is provided by the DFIG itself, and therefore
I Q ＝K(0.9-U pcc ) (3)
Wherein: i Q Reactive current required to be output for DFIG;
k is a reactive compensation coefficient;
U pcc the voltage per unit value of the grid-connected point power grid in the low-voltage crossing period;
DFIG output total active power P during low voltage ride through DFIG With rotor current i rd The following relationship exists:
Figure BDA0004111671590000082
wherein: p (P) DFIG Active power output by the DFIG;
s is slip;
i rd d-axis current of the rotor converter;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
L s is a stator inductance;
as is clear from (4), when the rotor-side current transformer d-axis current i rd At maximum, the DFIG outputs the total active power P DFIG Reaching the maximum;
s3, d-axis current i of rotor-side converter rd Reference value optimization
At rotor current I rmax Constrained rotor d-axis current i rd And q-axis current i rq There is a constraint represented by formula (5):
Figure BDA0004111671590000083
wherein: i rmax Maximum current allowed to pass when the rotor converter is safely operated;
i rd d-axis current of the rotor converter;
i rq q-axis current for the rotor converter;
as can be seen from (5), the d-axis current i of the rotor-side current transformer is to be set rd Maximum rotor q-axis current modulus value i rq I should be as small as possible on a satisfactory basis,
the reactive current of the DFIG during low voltage ride through is provided by the grid side converter and the DFIG stator together, namely:
I Q ＝i gq +i sq (6)
wherein: i Q Reactive current required to be output for DFIG;
i gq reactive current provided to the grid-side converter;
i sq reactive current provided to the DFIG stator;
DFIG stator output reactive power Q s Reactive current i with stator sq And rotor q-axis current i rq There is a relationship of formula (7):
Figure BDA0004111671590000091
wherein: q (Q) s Reactive power output for the DFIG stator;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
L s is a stator inductance;
ω s is the voltage electrical angular frequency;
i sq is stator q-axis current;
i rq q-axis current for the rotor;
from equation (7), i can be calculated sq And i rq As shown in the formula (8):
Figure BDA0004111671590000092
wherein: i.e sq Is stator q-axis current;
L s is a stator inductance;
ω s is the voltage electrical angular frequency;
i rq q-axis current for the rotor converter;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
as can be seen from (8), only when the rotor q-axis current i rq When the number of the groups is less than 0,the DFIG stator can output reactive current (i sq Greater than 0), and rotor q-axis current modulus value i rq The larger the I is, the stator outputs reactive current i sq The larger. As can be seen from (7) and (8), the rotor q-axis current modulus value i is to be set rq As small as possible, the grid-side converter should be used to output reactive current preferentially, and then the DFIG stator should be used to output reactive current;
s4, d-axis current i of grid-side converter gd_LVRT Reference value optimization
The control target of the grid-side converter is that the direct-current side voltage is stable, and the d-axis current reference value i of the grid-side converter during the low-voltage ride-through period gd_LVRT Obtained from the voltage outer loop, priority guarantees are required:
i gd_LVRT ＝i gdref (9)
wherein: i.e gd_LVRT The current reference value is the d-axis current reference value of the grid-side converter;
i gdref an active current reference value obtained for a voltage loop of the grid-side converter;
to ensure that the DFIG can output more active power, the network-side converter should be preferentially utilized to output reactive current during the low voltage ride through period, and the q-axis current reference value i thereof gq_LVRT The method comprises the following steps:
Figure BDA0004111671590000101
wherein: i.e gq_LVRT The current reference value is the q-axis current reference value of the grid-side converter;
I gmax maximum current allowed to pass for a grid-side converter, typically I gmax 0.3pu;
i gdref an active current reference value obtained for a voltage loop of the grid-side converter;
I Q reactive current required to be output for DFIG;
when the reactive current output capability of the network-side converter can meet the reactive current requirement of the system, namely
Figure BDA0004111671590000105
At this timeReactive current is output only by the grid-side converter without the DFIG stator outputting reactive current, i.e sq 0, according to equation (8), rotor-side converter current loop q-axis reference i rq_LVRT The method comprises the following steps:
Figure BDA0004111671590000102
wherein: i.e rq_LVRT A q-axis current reference value of the rotor-side converter;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
ω s is the voltage electrical angular frequency;
on the premise of meeting reactive power requirements of a power system, in order to ensure that the wind turbine can output active power as much as possible, a d-axis reference value i of a rotor-side converter rd_LVRT The method comprises the following steps:
Figure BDA0004111671590000103
wherein: i.e rd_LVRT The reference value is the d-axis current of the rotor-side converter;
i rq_LVRT a q-axis current reference value of the rotor-side converter;
I rmax maximum current allowed to pass for rotor-side converters, typically I rmax 1.2pu;
i rdref the active current reference value is obtained by maximum power tracking control;
when the reactive current output capability of the network-side converter cannot meet the reactive current requirement of the system, namely
Figure BDA0004111671590000104
At this time, the DFIG stator is also required to output reactive current. To ensure reactive current output preferentially, according to equation (8), the rotor-side converter current loop q-axis reference i rq_LVRT The method comprises the following steps: />
Figure BDA0004111671590000111
Wherein: i.e rq_LVRT A q-axis current reference value of the rotor-side converter;
i gq_LVRT the current reference value is the q-axis current reference value of the grid-side converter;
I Q reactive current required to be output for DFIG;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
L s is a stator inductance;
ω s is the voltage electrical angular frequency;
on the premise of meeting reactive power requirements of the system, in order to ensure that the wind turbine can output maximum active power, a d-axis reference value i of the rotor-side converter rd_LVRT Still given by equation (13).
The STATCOM wind power plant can increase the K value to more than 2 so as to improve the low voltage ride through capability. According to equations (9) - (13), STATCOM, grid side current transformer and rotor side current loop reference values during low voltage ride through can be given by fig. 4. A wind farm not equipped with STATCOM sets the K value to 1.5. According to equations (9) - (13), the net side current transformer and rotor side current transformer current loop reference values during low voltage ride through are given by the block diagram shown in fig. 5.
Although the embodiments of the present invention and the accompanying drawings have been disclosed for illustrative purposes, those skilled in the art will appreciate that: various substitutions, changes and modifications are possible without departing from the spirit and scope of the invention and the appended claims, and therefore the scope of the invention is not limited to the embodiments and the disclosure of the drawings.

Claims (1)

1. The control method for the maximum active power output during the low voltage ride through of the doubly-fed wind farm is characterized by comprising the following steps of: the method comprises the following steps:
s1, combining a doubly-fed wind power system and a doubly-fed wind power converter, and determining the injection requirement on reactive current when a wind power plant passes through at low voltage, wherein the injection requirement is as shown in the formula (1):
ΔI q ＝K×(0.9-U pcc )×I N ,(0.2≤U pcc ≤0.9) (1)
wherein: ΔI q Reactive current injection amount specified for the standard;
k is a reactive compensation coefficient;
U pcc the voltage per unit value is the grid-connected point voltage per unit value;
I N rated current for the wind farm;
s2, determining a reactive current output mode according to whether a reactive compensation device is configured in the wind farm:
for a wind farm provided with a reactive compensation device, the reactive compensation device is preferentially utilized to output reactive current during low-voltage ride through, and when the reactive compensation device does not output reactive current to meet the requirement, the DFIG is utilized to output reactive current, so that the reactive current I output by the DFIG is required during the low-voltage ride through Q The method comprises the following steps:
Figure FDA0004111671580000011
wherein: i Q Reactive current required to be output for DFIG;
k is a reactive compensation coefficient;
U pcc the voltage per unit value of the grid-connected point power grid in the low-voltage crossing period;
for wind farms not equipped with reactive compensation devices, the reactive current is provided by the DFIG itself, and therefore
I Q ＝K(0.9-U pcc ) (3)
Wherein: i Q Reactive current required to be output for DFIG;
k is a reactive compensation coefficient;
U pcc the voltage per unit value of the grid-connected point power grid in the low-voltage crossing period;
DFIG output total active power P during low voltage ride through DFIG With rotor current i rd The following relationship exists:
Figure FDA0004111671580000012
wherein: p (P) DFIG Active power output by the DFIG;
s is slip;
i rd d-axis current of the rotor converter;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
L s is a stator inductance;
as is clear from (4), when the rotor-side current transformer d-axis current i rd At maximum, the DFIG outputs the total active power P DFIG Reaching the maximum;
s3, d-axis current i of rotor-side converter rd Reference value optimization
At rotor current I rmax Constrained rotor d-axis current i rd And q-axis current i rq There is a constraint represented by formula (5):
Figure FDA0004111671580000021
wherein: i rmax Maximum current allowed to pass when the rotor converter is safely operated;
i rd d-axis current of the rotor converter;
i rq q-axis current for the rotor converter;
as can be seen from (5), the d-axis current i of the rotor-side current transformer is to be set rd Maximum rotor q-axis current modulus value i rq I should be as small as possible on a satisfactory basis,
the reactive current of the DFIG during low voltage ride through is provided by the grid side converter and the DFIG stator together, namely:
I Q ＝i gq +i sq (6)
wherein: i Q Reactive current required to be output for DFIG;
i gq reactive current provided to the grid-side converter;
i sq reactive current provided to the DFIG stator;
DFIG stator output reactive power Q s Reactive current i with stator sq And rotor q-axis current i rq There is a relationship of formula (7):
Figure FDA0004111671580000022
wherein: q (Q) s Reactive power output for the DFIG stator;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
L s is a stator inductance;
ω s is the voltage electrical angular frequency;
i sq is stator q-axis current;
i rq q-axis current for the rotor;
from equation (7), i can be calculated sq And i rq As shown in the formula (8):
Figure FDA0004111671580000023
wherein: i.e sq Is stator q-axis current;
L s is a stator inductance;
ω s is the voltage electrical angular frequency;
i rq q-axis current for the rotor converter;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
as can be seen from (8), only when the rotor q-axis current i rq If the voltage is less than 0, the DFIG stator can output reactive current (i sq Greater than 0), and rotor q-axis current modulus value i rq The larger the I is, the stator outputs reactive current i sq The larger; as can be seen from (7) and (8), the rotor q-axis current modulus value i is to be set rq As small as possible, the grid-side converter should be used to output reactive current preferentially, and then the DFIG stator should be used to output reactive current;
s4, d-axis current i of grid-side converter gd_LVRT Reference value optimization
The control target of the grid-side converter is that the direct-current side voltage is stable, and the d-axis current reference value i of the grid-side converter during the low-voltage ride-through period gd_LVRT Obtained from the voltage outer loop, priority guarantees are required:
i gd_LVRT ＝i gdref (9)
wherein: i.e gd_LVRT The current reference value is the d-axis current reference value of the grid-side converter;
i gdref an active current reference value obtained for a voltage loop of the grid-side converter;
to ensure that the DFIG can output more active power, the network-side converter should be preferentially utilized to output reactive current during the low voltage ride through period, and the q-axis current reference value i thereof gq_LVRT The method comprises the following steps:
Figure FDA0004111671580000031
wherein: i.e gq_LVRT The current reference value is the q-axis current reference value of the grid-side converter;
I gmax maximum current allowed to pass for a grid-side converter, typically I gmax 0.3pu;
i gdref an active current reference value obtained for a voltage loop of the grid-side converter;
I Q reactive current required to be output for DFIG;
when the reactive current output capability of the network-side converter can meet the reactive current requirement of the system, namely
Figure FDA0004111671580000032
In this case, only the network-side converter outputs reactive current, without the DFIG stator outputting reactive current, i sq 0, according to equation (8), rotor-side converter current loop q-axis reference i rq_LVRT The method comprises the following steps:
Figure FDA0004111671580000033
wherein: i.e rq_LVRT A q-axis current reference value of the rotor-side converter;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
ω s is the voltage electrical angular frequency;
on the premise of meeting reactive power requirements of a power system, in order to ensure that the wind turbine can output active power as much as possible, a d-axis reference value i of a rotor-side converter rd_LVRT The method comprises the following steps:
Figure FDA0004111671580000041
wherein: i.e rd_LVRT The reference value is the d-axis current of the rotor-side converter;
i rq_LVRT a q-axis current reference value of the rotor-side converter;
I rmax maximum current allowed to pass for rotor-side converters, typically I rmax 1.2pu;
i rdref the active current reference value is obtained by maximum power tracking control;
when the reactive current output capability of the network-side converter cannot meet the reactive current requirement of the system, namely
Figure FDA0004111671580000042
At this time, the DFIG stator is required to output reactive current, and the rotor-side converter current loop q-axis reference value i is given by equation (8) to ensure reactive current output preferentially rq_LVRT The method comprises the following steps:
Figure FDA0004111671580000043
wherein: i.e rq_LVRT A q-axis current reference value of the rotor-side converter;
i gq_LVRT the current reference value is the q-axis current reference value of the grid-side converter;
I Q reactive current required to be output for DFIG;
L m exciting an inductor for the DFIG;
U pcc is the voltage of the grid-connected point;
L s is a stator inductance;
ω s is the voltage electrical angular frequency;
on the premise of meeting reactive power requirements of the system, in order to ensure that the wind turbine can output maximum active power, a d-axis reference value i of the rotor-side converter rd_LVRT Still given by equation (13).
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Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102570503A (en) * 2011-12-30 2012-07-11 东方电气集团东方汽轮机有限公司 Double-fed wind power generation system
CN103326368A (en) * 2013-06-13 2013-09-25 国家电网公司 Dynamic reactive current direct control method by doubly-fed wind turbine generator set during grid fault
CN104362667A (en) * 2014-10-16 2015-02-18 中国人民解放军装甲兵工程学院 Cooperative control method of high and low voltage ride-through for doubly-fed wind turbine set
US20150077067A1 (en) * 2013-06-25 2015-03-19 Masdar Institute Of Science And Technology Fault-tolerant wind energy conversion system
CN104795842A (en) * 2015-05-11 2015-07-22 重庆大学 Symmetrical fault ride-through control method for hybrid wind farm group containing double-fed wind farm and permanent magnetic direct drive wind farm
CN105098833A (en) * 2015-08-12 2015-11-25 国网山东省电力公司电力科学研究院 Asynchronous constant speed wind turbine system for micro grid and working method thereof
CN105429166A (en) * 2015-07-01 2016-03-23 上海电机学院 PMSG low-voltage ride through system based on reactive power control
CN107425539A (en) * 2017-06-26 2017-12-01 重庆大学 The enhancing low voltage traversing control method of double-fed fan motor unit under unbalanced grid faults
CN107579540A (en) * 2017-08-18 2018-01-12 河海大学 A kind of marine wind electric field resultant fault traversing method grid-connected based on HVAC
CN109378860A (en) * 2018-12-14 2019-02-22 重庆大学 A kind of low-voltage traversing
CN109617125A (en) * 2019-01-02 2019-04-12 上海交通大学 Double-fed fan motor unit high-low voltage ride through system and method based on stator string impedance
CN113765146A (en) * 2021-11-09 2021-12-07 四川大学 Double-fed induction fan fault ride-through system and method under direct-current commutation failure
WO2021258508A1 (en) * 2020-06-22 2021-12-30 山东大学 Low-voltage ride-through control method and system for wind turbine generator
WO2022027717A1 (en) * 2020-08-04 2022-02-10 西安热工研究院有限公司 Method for enhancing low voltage ride-through capability in photovoltaic power generation
CN115425689A (en) * 2022-09-30 2022-12-02 华北电力大学 Doubly-fed wind turbine generator rotor side fault ride-through control method and system and electronic equipment

Patent Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102570503A (en) * 2011-12-30 2012-07-11 东方电气集团东方汽轮机有限公司 Double-fed wind power generation system
CN103326368A (en) * 2013-06-13 2013-09-25 国家电网公司 Dynamic reactive current direct control method by doubly-fed wind turbine generator set during grid fault
US20150077067A1 (en) * 2013-06-25 2015-03-19 Masdar Institute Of Science And Technology Fault-tolerant wind energy conversion system
CN104362667A (en) * 2014-10-16 2015-02-18 中国人民解放军装甲兵工程学院 Cooperative control method of high and low voltage ride-through for doubly-fed wind turbine set
CN104795842A (en) * 2015-05-11 2015-07-22 重庆大学 Symmetrical fault ride-through control method for hybrid wind farm group containing double-fed wind farm and permanent magnetic direct drive wind farm
CN105429166A (en) * 2015-07-01 2016-03-23 上海电机学院 PMSG low-voltage ride through system based on reactive power control
CN105098833A (en) * 2015-08-12 2015-11-25 国网山东省电力公司电力科学研究院 Asynchronous constant speed wind turbine system for micro grid and working method thereof
CN107425539A (en) * 2017-06-26 2017-12-01 重庆大学 The enhancing low voltage traversing control method of double-fed fan motor unit under unbalanced grid faults
CN107579540A (en) * 2017-08-18 2018-01-12 河海大学 A kind of marine wind electric field resultant fault traversing method grid-connected based on HVAC
CN109378860A (en) * 2018-12-14 2019-02-22 重庆大学 A kind of low-voltage traversing
CN109617125A (en) * 2019-01-02 2019-04-12 上海交通大学 Double-fed fan motor unit high-low voltage ride through system and method based on stator string impedance
WO2021258508A1 (en) * 2020-06-22 2021-12-30 山东大学 Low-voltage ride-through control method and system for wind turbine generator
WO2022027717A1 (en) * 2020-08-04 2022-02-10 西安热工研究院有限公司 Method for enhancing low voltage ride-through capability in photovoltaic power generation
CN113765146A (en) * 2021-11-09 2021-12-07 四川大学 Double-fed induction fan fault ride-through system and method under direct-current commutation failure
CN115425689A (en) * 2022-09-30 2022-12-02 华北电力大学 Doubly-fed wind turbine generator rotor side fault ride-through control method and system and electronic equipment

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
YIZHEN WANG等: "A Practical DC Fault Ride-Through Method for MMC Based MVDC Distribution Systems", IEEE TRANSACTIONS ON POWER DELIVERY, vol. 4, no. 36, 2 June 2022 (2022-06-02) *
周玉琦;李东东;梁自超;: "故障下双馈感应风力发电机无功协调控制策略", 电力系统及其自动化学报, no. 07, 15 July 2016 (2016-07-15) *
李斌等: "考虑撬棒保护的双馈风力发电机定子短路电流计算", 《电力系统及其自动化学报》, vol. 29, no. 4, 30 April 2017 (2017-04-30) *
李辉;付博;杨超;赵斌;唐显虎;: "双馈风电机组低电压穿越的无功电流分配及控制策略改进", 中国电机工程学报, no. 22, 5 August 2012 (2012-08-05) *
王凯;朱凌;王晓蔚;: "双馈电机风电场低电压穿越方案的研究", 通信电源技术, no. 06, 25 November 2012 (2012-11-25) *

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