CN108667081B - Self-closed electromagnetic coupling speed regulation wind turbine generator control method adopting reactive power priority mode - Google Patents
Self-closed electromagnetic coupling speed regulation wind turbine generator control method adopting reactive power priority mode Download PDFInfo
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- 238000005859 coupling reaction Methods 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 title claims abstract description 14
- 230000001360 synchronised effect Effects 0.000 claims abstract description 33
- 238000007789 sealing Methods 0.000 claims description 9
- 230000005284 excitation Effects 0.000 claims description 6
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- 238000002360 preparation method Methods 0.000 claims 1
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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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- 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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Abstract
The invention provides a method for adopting a reactive power priority modeThe self-closed electromagnetic coupling speed regulation wind turbine generator control method adopts a reactive power priority mode during the voltage drop of a power grid, firstly calculates reactive current, and controls an electrically excited synchronous generator to send out reactive current iq(ii) a And then calculating a torque instruction of the frequency converter, and judging whether the torque instruction of the frequency converter is reduced in the period of the voltage drop of the power grid or not according to the rotating speed of the wind wheel at the voltage drop moment of the power grid. The invention enables the unit to generate three times of rated current reactive current during the voltage drop of the power grid, and effectively supports the voltage of the power grid; on the basis of ensuring the reactive current and the short-time maximum allowable current, the active current is maximized in the voltage drop period of the power grid, and the maximum support of the voltage of the power grid and the improvement of the load of a variable pitch system are realized.
Description
Technical Field
The invention relates to the field of wind generating sets, in particular to a control method for a self-sealing type electromagnetic coupling speed-regulating wind generating set.
Background
As shown in fig. 1, the self-sealing type electromagnetic coupling speed regulation wind turbine generator adopts a self-sealing type electromagnetic coupling speed regulation device to connect a high-speed shaft of a gear box and a rotor shaft of an electrically excited synchronous generator, so that power is transmitted from the gear box 2 side to the electrically excited synchronous generator side, and a grid-connected interface is an electrically excited synchronous generator 5; the self-closed electromagnetic coupling speed regulating device consists of an electromagnetic coupler 4, a frequency converter 6 and a permanent magnet synchronous generator 3, wherein the permanent magnet synchronous generator 3 is used for supplying power to the frequency converter 6; the electromagnetic coupler 4 is provided with two rotating shafts which are respectively connected with the gear box 2 and the electric excitation synchronous generator 5 and rotate, and the frequency converter 6 controls the relative rotating speed and the electromagnetic torque of the two rotating shafts of the electromagnetic coupler 4; the high-speed shaft of the gear box is connected with one shaft of the electromagnetic coupler to form a front shaft system, the other shaft of the electromagnetic coupler is connected with a rotor shaft of the electrically excited synchronous generator 5 to form a rear shaft system, the front shaft system and the rear shaft system are 2 independent shaft systems, and the permanent magnet synchronous generator 3 and the front shaft system are coaxial to supply power to the frequency converter 6.
When the power grid fails, the voltage of the power grid drops and exceeds the normal range, the existing control strategy of the self-closed electromagnetic coupling speed regulation wind turbine generator set is switched into a low-voltage ride-through control mode, and because the frequency converter is powered by the permanent magnet synchronous generator coaxial with the high-speed shaft of the gearbox, the drop of the voltage of the power grid cannot cause the variable-frequency ride-through control modeThe power supply of the device is influenced, and in order to keep the output active current of the unit constant, the torque command value T of the frequency convertercmd_LVRTThe calculation formula of (2) is as follows:
Tcmd_LVRT＝kTcmd(1)
where k is the per unit value of the grid voltage, TcmdThe torque instruction value of the frequency converter at the time of grid voltage drop is obtained by an optimal mechanical characteristic curve of a wind wheel of the self-closed electromagnetic coupling speed-regulating wind turbine generator, the pitch angle is obtained as the same as the pitch angle when the grid voltage is normal, and the pitch angle is obtained by a PI regulator according to a target value and an actual value of the rotating speed of the wind wheel.
However, the influence of wind speed on the system, T, when the power grid fails is not considered in the existing control strategycmdThe torque instruction value of the frequency converter is obtained from the optimal mechanical characteristic curve of the wind wheel when the self-closed electromagnetic coupling speed regulation wind turbine generator set operates basically, and the larger the wind speed is, the T iscmdThe larger the wind speed, the smaller TcmdThe smaller the size due to △ Tcmd＝(1-k)TcmdTherefore, the greater the wind speed, △ TcmdThe larger the wind speed, the smaller the △ TcmdThe smaller, △ TcmdIs the load that the pitch system needs to bear, and the pitch system comprises a fan rotor and an attached motor for pitch control, △ TcmdThe larger the size, the greater the influence on the service life of the wind wheel and the variable pitch motor.
At present, the influence of wind speed on a torque instruction value of a frequency converter is not considered when a power grid fails in a self-closed electromagnetic coupling speed regulation wind turbine generator, so that the service life of a variable pitch system can be influenced when the variable pitch system bears a large load.
Disclosure of Invention
In order to solve the defects of the prior art, the invention provides a self-closed electromagnetic coupling speed regulation wind turbine generator control method in a reactive power priority mode.
The technical scheme of the invention is realized as follows:
a self-sealing electromagnetic coupling speed regulation wind turbine generator control method adopting a reactive power priority mode adopts a self-sealing electromagnetic coupling speed regulation device to be connected with a high-speed shaft of a gear box and a rotor shaft of an electrically excited synchronous generator so as to enable power to be transmitted from the side of the gear box to the side of the electrically excited synchronous generator, and a grid-connected interface is the electrically excited synchronous generator; the self-closed electromagnetic coupling speed regulating device consists of an electromagnetic coupler, a frequency converter and a permanent magnet synchronous generator, wherein the permanent magnet synchronous generator is used for supplying power to the frequency converter; the electromagnetic coupler is provided with two rotating shafts which are respectively connected with the gear box and the electrically excited synchronous generator and rotate, and the frequency converter controls the relative rotating speed and the electromagnetic torque of the two rotating shafts of the electromagnetic coupler;
during the voltage drop of the power grid, a reactive power priority mode is adopted, reactive current is calculated firstly, and the reactive current is calculated as follows:
iq＝3irated
iratedfor rated current, i.e. for generating three times rated current of reactive current to support network voltage, controlling said electrically excited synchronous generator to generate said reactive current iq；
And then calculating a torque instruction of the frequency converter, and judging whether the torque instruction of the frequency converter is reduced in the period of the voltage drop of the power grid or not according to the rotating speed of the wind wheel at the voltage drop moment of the power grid.
Optionally, when the wind turbine speed when the grid voltage drops is less than the per unit value t,
active current isMaximum limit value of (i), i.e. maximum allowable active current value ismaxThe calculation is as follows:
imaxthe short-time maximum allowable current value of the grid-connected electric excitation synchronous generator is obtained;
if is≤ismaxKeeping the active current i at the time of the grid voltage dropsInvariable, frequency converter torque command value Tcmd_LVRTThe calculation formula is as follows:
Tcmd_LVRT＝kTcmd(1)
if is>ismaxTorque command T of frequency convertercmd_LVRTThe calculation formula is as follows:
Tcmd_LVRT＝Tcmd*(ismax/is) (2)
in the formula isIs the active current at the moment of the grid voltage drop, k is the per unit value of the grid voltage, TcmdAnd the torque instruction value of the frequency converter at the moment of the voltage drop of the power grid.
Optionally, when the wind wheel rotating speed is greater than or equal to the per unit value t when the grid voltage drops, the active current isMaximum limit value of (i), i.e. maximum allowable active current value ismaxThe calculation is as follows:
imaxthe short-time maximum allowable current value of the grid-connected electric excitation synchronous generator is obtained;
if is/k≤ismaxKeeping the converter torque command before the grid voltage sag unchanged, Tcmd_LVRT＝Tcmd；
If is/k>ismaxTorque command T of frequency convertercmd_LVRTThe calculation formula is as follows:
Tcmd_LVRT＝Tcmd*(ismax/is) (3)
isis the active current at the moment of the grid voltage drop, k is the per unit value of the grid voltage, TcmdAnd the torque instruction value of the frequency converter at the moment of the voltage drop of the power grid.
The invention has the beneficial effects that:
(1) the unit can generate three times of rated current reactive current during the voltage drop of the power grid, and the voltage of the power grid is effectively supported;
(2) on the basis of ensuring the reactive current and the short-time maximum allowable current (namely ensuring that the short-time current does not exceed the limit, namely ensuring the safe operation of the generator), the active current is maximized during the voltage drop of the power grid, the maximum support of the voltage of the power grid is realized (from the view of supporting the voltage of the power grid), and the load of a variable pitch system is improved (from the view of reducing the load of the variable pitch system and the whole unit).
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a self-sealing type electromagnetic coupling speed regulation wind turbine;
fig. 2 is a flowchart of a control method of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The existing control strategy of the self-closed electromagnetic coupling speed regulation wind turbine generator does not consider the influence of the wind speed on the torque instruction value of the frequency converter when the power grid fails, so that the service life of a variable pitch system can be influenced when the variable pitch system bears a large load.
The invention provides a self-closed electromagnetic coupling speed regulation wind turbine generator control method adopting a reactive power priority mode, which considers the influence of wind speed on the load borne by a variable pitch system and realizes the protection of the variable pitch system.
The control method is used for controlling the self-closed electromagnetic coupling speed regulation wind turbine generator set shown in the figure 1 in the period of grid faults, and adopts a reactive power priority mode to calculate reactive current firstly in the period of grid voltage drop, and the reactive current is calculated as follows:
iq＝3irated
iratedfor rated current, i.e. for generating three times rated current of reactive current to support network voltage, controlling said electrically excited synchronous generator to generate said reactive current iq；
And then calculating a torque command of the frequency converter:
active current isMaximum limit value of (i), i.e. maximum allowable active current value ismaxThe calculation is as follows:
imaxthe short-time maximum allowable current value of the grid-connected electric excitation synchronous generator is obtained;
according to the wind wheel rotating speed at the time of grid voltage drop, whether a torque instruction of a frequency converter is reduced in the period of grid voltage drop is judged, and the judging process is as follows:
when the wind wheel rotating speed at the time when the grid voltage drops is less than a per unit value t (t is the actual wind wheel rotating speed/wind wheel rotating speed rated value, for example, the wind wheel rotating speed rated value is 17.4rpm), the current wind speed is smaller, and the current unit outputs smaller active power;
if is≤ismaxKeeping the active current i at the time of the grid voltage dropsInvariable, frequency converter torque command value Tcmd_LVRTThe calculation formula is as follows:
Tcmd_LVRT＝kTcmd(1)
if is>ismaxTorque command T of frequency convertercmd_LVRTThe calculation formula is as follows:
Tcmd_LVRT＝Tcmd*(ismax/is) (2)
in the formula isIs the active current at the moment of the grid voltage drop, k is the per unit value of the grid voltage, TcmdAnd the torque instruction value of the frequency converter at the moment of the voltage drop of the power grid.
When the rotating speed of the wind wheel is greater than or equal to t when the voltage of the power grid drops, the current wind speed is higher, and the active power output by the current wind turbine generator is higherLarge, TcmdLarger if still in accordance with kTcmdCalculating the torque instruction of the frequency converter during the voltage drop of the power grid, the torque changes △ TcmdLarge, in order to prevent the wind turbine from over-speeding, the pitch system must be feathered at a fast speed;
if is/k≤ismaxKeeping the converter torque command before the grid voltage sag unchanged, Tcmd_LVRT＝Tcmd；
If is/k>ismaxTorque command T of frequency convertercmd_LVRTThe calculation formula is as follows:
Tcmd_LVRT＝Tcmd*(ismax/is) (3)
isis the active current at the moment of the grid voltage drop, k is the per unit value of the grid voltage, TcmdAnd the torque instruction value of the frequency converter at the moment of the voltage drop of the power grid.
In a conventional power plant, a synchronous generator can generate reactive current of three times rated current to effectively support the voltage of a power grid during the voltage drop of the power grid, and because a grid-connected interface of the wind turbine generator set is also an electrically excited synchronous generator, the synchronous generator in the conventional power plant is simulated to generate the reactive current of three times rated current during the voltage drop of the power grid, so that the voltage of the power grid is effectively supported;
on the basis of ensuring the reactive current and the short-time maximum allowable current (namely ensuring that the short-time current does not exceed the limit, namely ensuring the safe operation of the generator), the control method maximizes the active current during the voltage drop of the power grid, and realizes the maximum support of the voltage of the power grid (from the view of the voltage support of the power grid) and the improvement of the load of a variable pitch system (from the view of reducing the load of the variable pitch system and the whole unit).
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (2)
1. A self-sealing electromagnetic coupling speed regulation wind turbine generator control method adopting a reactive power priority mode adopts a self-sealing electromagnetic coupling speed regulation device to be connected with a high-speed shaft of a gear box and a rotor shaft of an electrically excited synchronous generator so as to enable power to be transmitted from the side of the gear box to the side of the electrically excited synchronous generator, and a grid-connected interface is the electrically excited synchronous generator; the self-closed electromagnetic coupling speed regulating device consists of an electromagnetic coupler, a frequency converter and a permanent magnet synchronous generator, wherein the permanent magnet synchronous generator is used for supplying power to the frequency converter; the electromagnetic coupler is provided with two rotating shafts which are respectively connected with the gear box and the electrically excited synchronous generator and rotate, and the frequency converter controls the relative rotating speed and the electromagnetic torque of the two rotating shafts of the electromagnetic coupler; it is characterized in that the preparation method is characterized in that,
during the voltage drop of the power grid, a reactive power priority mode is adopted, reactive current is calculated firstly, and the reactive current is calculated as follows:
iq＝3 irated
iratedfor rated current, i.e. for generating three times rated current of reactive current to support network voltage, controlling said electrically excited synchronous generator to generate said reactive current iq；
Then calculating a torque instruction of the frequency converter, and judging whether the torque instruction of the frequency converter is reduced in the period of the voltage drop of the power grid or not according to the rotating speed of the wind wheel at the voltage drop moment of the power grid; when the wind wheel rotating speed is less than the per unit value t when the voltage of the power grid drops,
active current isMaximum limit value of (i), i.e. maximum allowable active current value ismaxThe calculation is as follows:
imaxthe short-time maximum allowable current value of the grid-connected electric excitation synchronous generator is obtained;
if is≤ismaxKeeping the active current i at the time of the grid voltage dropsInvariably, frequency converter torque command Tcmd_LVRTThe calculation formula is as follows:
Tcmd_LVRT＝kTcmd(1)
if is>ismaxTorque command T of frequency convertercmd_LVRTThe calculation formula is as follows:
Tcmd_LVRT＝Tcmd*(ismax/is) (2)
in the formula isIs the active current at the moment of the grid voltage drop, k is the per unit value of the grid voltage, TcmdAnd the torque instruction value of the frequency converter at the moment of the voltage drop of the power grid.
2. The self-sealing type electromagnetic coupling speed regulation wind turbine generator control method adopting the reactive power priority mode as claimed in claim 1, wherein when the wind wheel rotation speed is greater than or equal to the per unit value t when the grid voltage drops, the active current i issMaximum limit value of (i), i.e. maximum allowable active current value ismaxThe calculation is as follows:
imaxthe short-time maximum allowable current value of the grid-connected electric excitation synchronous generator is obtained;
if is/k≤ismaxKeeping the converter torque command before the grid voltage sag unchanged, Tcmd_LVRT＝Tcmd；
If is/k>ismaxTorque command T of frequency convertercmd_LVRTThe calculation formula is as follows:
Tcmd_LVRT＝Tcmd*(ismax/is) (3)
isis the active current at the moment of the grid voltage drop, k is the per unit value of the grid voltage, TcmdAnd the torque instruction value of the frequency converter at the moment of the voltage drop of the power grid.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102155356A (en) * | 2011-03-22 | 2011-08-17 | 国电联合动力技术有限公司 | Method for controlling running of wind generating set based on speed-regulating front end of electromagnetic coupler |
| CN103094917A (en) * | 2012-11-27 | 2013-05-08 | 哈电通用风能（江苏）有限公司 | Low voltage ride through control method for full-power high-speed permanent synchronous fan |
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| US8674536B2 (en) * | 2011-11-30 | 2014-03-18 | Iqwind Ltd. | Wind turbine with variable speed auxiliary generator and load sharing algorithm |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102155356A (en) * | 2011-03-22 | 2011-08-17 | 国电联合动力技术有限公司 | Method for controlling running of wind generating set based on speed-regulating front end of electromagnetic coupler |
| CN103094917A (en) * | 2012-11-27 | 2013-05-08 | 哈电通用风能（江苏）有限公司 | Low voltage ride through control method for full-power high-speed permanent synchronous fan |
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