CN112523943A - Additional control method and system for restraining transient overvoltage of direct-drive fan - Google Patents
Additional control method and system for restraining transient overvoltage of direct-drive fan Download PDFInfo
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- 230000001052 transient effect Effects 0.000 title claims abstract description 47
- 238000000034 method Methods 0.000 title claims abstract description 18
- 230000000452 restraining effect Effects 0.000 title description 2
- 238000012937 correction Methods 0.000 claims abstract description 107
- 230000008859 change Effects 0.000 claims abstract description 55
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims description 30
- 230000004044 response Effects 0.000 claims description 13
- 238000012546 transfer Methods 0.000 claims description 12
- 230000000670 limiting effect Effects 0.000 claims description 9
- 238000005457 optimization Methods 0.000 claims description 9
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- 230000004069 differentiation Effects 0.000 claims description 5
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- 238000005259 measurement Methods 0.000 claims description 3
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- 238000010586 diagram Methods 0.000 description 7
- 238000010248 power generation Methods 0.000 description 4
- 238000013016 damping Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
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- XOFYZVNMUHMLCC-ZPOLXVRWSA-N prednisone Chemical compound O=C1C=C[C@]2(C)[C@H]3C(=O)C[C@](C)([C@@](CC4)(O)C(=O)CO)[C@@H]4[C@@H]3CCC2=C1 XOFYZVNMUHMLCC-ZPOLXVRWSA-N 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03D—WIND MOTORS
- F03D7/00—Controlling wind motors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05B2270/00—Control
- F05B2270/30—Control parameters, e.g. input parameters
- F05B2270/337—Electrical grid status parameters, e.g. voltage, frequency or power demand
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05B2270/00—Control
- F05B2270/70—Type of control algorithm
- F05B2270/705—Type of control algorithm proportional-integral
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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
- Y02E10/72—Wind turbines with rotation axis in wind direction
Abstract
The invention discloses an additional control method and system for suppressing transient overvoltage of a direct-drive fan, belonging to the field of voltage safety control of a power system, and comprising the following steps of: when the voltage of the end of the direct-drive fan rises, a voltage correction signal is generated according to the change index of the end voltage, the voltage correction signal is used as a feedforward control signal and is added to the output end of a PI (proportional integral) controller in the current control link of the grid-side converter of the direct-drive fan, and d and q axis components of equivalent internal potential of the direct-drive fan output by the PI controller are corrected to reduce the output voltage of an equivalent power supply, so that the transient overvoltage of the direct-drive fan is restrained. The transient overvoltage suppression device can effectively suppress transient overvoltage of the direct-drive fan, ensures safe operation of a power system, only responds to the situation that the terminal voltage rises, does not act when the terminal voltage is unchanged or falls, and can not influence the normal control of the direct-drive fan under the situation that the transient overvoltage suppression is ensured.
Description
Technical Field
The invention belongs to the field of voltage safety control of a power system, and particularly relates to an additional control method and system for suppressing transient overvoltage of a direct-drive fan.
Background
In recent years, with the increasing proportion of wind power generation in an electric power system, the wind power generation has become a core factor for determining the dynamic behavior of the system, and a controller is a core factor for determining the dynamic characteristic of a wind power generator.
With the wide application of the direct-drive fan in the power system, the transient overvoltage problem frequently occurs, and the safe operation of the power system is damaged. The occurrence of the transient overvoltage problem of the direct-drive fan seriously damages the power supply quality and the power supply safety, can cause a series of problems such as fan off-line and adjacent line tripping, and has great threat to the safe operation of the power system. At present, the common terminal voltage feedforward control applied to the direct-drive fan acquires the terminal voltage as a feedforward control signal, so that the output voltage of the equivalent power supply of the direct-drive fan can quickly respond to the change of the network side voltage, and the overcurrent is reduced.
Although the terminal voltage feedforward control can protect the direct-drive fan from being impacted by overcurrent, the conventional feedforward control can only ensure that the output voltage of the equivalent voltage of the direct-drive fan can quickly track the change of the terminal voltage, the problem of transient overvoltage of the direct-drive fan is not considered, and the transient overvoltage in the direct-drive fan cannot be effectively inhibited.
Disclosure of Invention
Aiming at the defects and the improvement requirements of the prior art, the invention provides an additional control method and an additional control system for suppressing the transient overvoltage of a direct-drive fan, and aims to effectively suppress the transient overvoltage of the direct-drive fan so as to ensure the safe operation of a power system.
To achieve the above object, according to one aspect of the present invention, an additional control method for suppressing transient overvoltage of a direct drive wind turbine is provided, including:
when the voltage of the end of the direct-drive fan rises, a voltage correction signal is generated according to the change index of the end voltage, the voltage correction signal is added to the output end of a PI (proportional integral) controller in the current control link of the grid-side converter of the direct-drive fan, and d-axis and q-axis components of equivalent internal potential of the direct-drive fan output by the PI controller are corrected, so that the output voltage of an equivalent power supply of the direct-drive fan is reduced, and the transient overvoltage of the direct-drive fan is restrained.
Further, the mode of judging whether the voltage of the direct-drive fan terminal rises comprises the following steps:
if Δ V > Tsd1Judging that the voltage of the direct-drive fan terminal rises;
or
Judging the voltage rise of the direct drive fan terminal;
wherein V represents the terminal voltage of the direct-drive fan, and delta V represents the variation of the terminal voltage of the direct-drive fan;
represents the rate of change of terminal voltage V; tsd1And Tsd2Indicates the judgment threshold value, and Tsd1>0，Tsd2>0。
Further, the change index of the terminal voltage is the change amount of the terminal voltage or the change rate of the terminal voltage;
the specific mode of generating the voltage correction signal according to the change index of the terminal voltage is as follows:
and performing one or more operations of gain, filtering and differentiation on the variation index of the terminal voltage to generate a voltage correction signal.
Further, performing one or more of gain, filtering, and differentiation on the variation index of the terminal voltage to generate a voltage correction signal, including:
according to Edctrl＝k1ΔVd、Eqctrl＝k2ΔVqRespectively generating d-axis components E of the voltage correction signalsdctrlAnd q-axis component Eqctrl；
Or, according to
Respectively generate voltage calibrationD-axis component E of positive signaldctrlAnd q-axis component Eqctrl；
Or, according to
Respectively generating d-axis components E of the voltage correction signalsdctrlAnd q-axis component Eqctrl；
Wherein V represents the terminal voltage of the direct-drive fan, and delta V represents the variation of the terminal voltage of the direct-drive fan; vdAnd VqRespectively representing d-axis component and q-axis component, delta V, of terminal voltage of the direct-drive fan under a phase-locked coordinate systemdAnd Δ VqRespectively represent VdAnd VqThe amount of change in (c);
and
respectively represent VdAnd VqThe rate of change of (c); k is a radical of1And k2As a gain parameter, k3～k10For the filter parameters, s is the differential operator.
According to another aspect of the invention, an additional control system for suppressing transient overvoltage of a direct drive wind turbine is provided, which comprises: the terminal voltage measuring module, the control starting module, the voltage correction signal generating module and the terminal voltage response optimizing module;
the terminal voltage measuring module is connected with the output end of the direct-drive fan and is used for measuring the terminal voltage V of the direct-drive fan, and/or the terminal voltage variation rate, and the d-axis component V of the terminal voltage of the direct-drive fandAnd q-axis component Vq；
The input end of the control starting module is connected with the output end of the terminal voltage measuring module and is used for judging whether the terminal voltage of the direct-drive fan rises or not according to the measuring result of the terminal voltage measuring module and generating a corresponding control starting signal; when the end voltage of the starting signal rises, the voltage correction signal generation module is indicated to start working; when the terminal voltage of the control starting signal is reduced or maintained unchanged, indicating that the voltage correction signal generation module does not work;
the input end of the voltage correction signal generation module is connected with the control starting module and the output end of the terminal voltage measurement module, and the voltage correction signal generation module is used for generating a voltage correction signal according to the change index of the terminal voltage when the control starting module indicates that the voltage correction signal generation module starts to work;
and a first input end of the terminal voltage response optimization module is connected with an output end of the voltage correction signal generation module, a second input end of the terminal voltage response optimization module is connected with an output end of a PI (proportional integral) controller in the current control link of the direct-drive fan grid-side converter, and the terminal voltage response optimization module is used for attaching the voltage correction signal as a feedforward control signal to the output end of the PI controller in the current control link of the direct-drive fan grid-side converter, correcting d and q-axis components of equivalent internal potential of the direct-drive fan output by the PI controller, and reducing the output voltage of an equivalent power supply so as to inhibit transient overvoltage of the.
In some optional embodiments, the voltage correction signal generation module comprises: a first gain amplifier, a second gain amplifier and a first limiter;
a first gain amplifier having an input connected to the input and the output of the terminal voltage measuring module, and arranged according to Edctrl＝k1ΔVdGenerating a d-axis component E of a voltage correction signaldctrl；
A second gain amplifier having an input connected to the input and the output of the terminal voltage measuring module, and arranged to operate according to Eqctrl＝k2ΔVqGenerating a q-axis component E of a voltage correction signalqctrl；
A first amplitude limiter, whose input end is connected with the output ends of the first gain amplifier and the second gain amplifier, and whose output end is used as the output end of the voltage correction signal generation module, which is used for the d-axis component E of the voltage correction signaldctrlAnd q-axis component EqctrlCarrying out amplitude limiting operation;
wherein, is Δ VdAnd Δ VqRespectively represent VdAnd VqThe amount of change in (c); k is a radical of1And k2For the gain parameter, s is the differential operator.
In some optional embodiments, the voltage correction signal generation module comprises: a first generating unit, a second generating unit and a second slicer;
a first generating unit, the input end of which is connected with the output end of the terminal voltage measuring module, and the transfer function of which is
A first generating unit for generating
Generating a d-axis component E of a voltage correction signaldctrl；
A second generating unit, the input end of which is connected with the output end of the terminal voltage measuring module and the transfer function of which is
A second generating unit for generating
Generating a q-axis component E of a voltage correction signalqctrl；
A second amplitude limiter, whose input end is connected with the output ends of the first and second generating units, and whose output end is used as the output end of the voltage correction signal generating module, and is used for correcting the d-axis component E of the voltage correction signaldctrlAnd q-axis component EqctrlCarrying out amplitude limiting operation;
wherein the content of the first and second substances,
and
respectively represent VdAnd VqThe rate of change of (c); k is a radical of3～k6For the gain parameter, s is the differential operator.
In some optional embodiments, the voltage correction signal generation module comprises: a third generation unit, a fourth generation unit and a third limiter;
a third generating unit, the input end of which is connected with the output end of the terminal voltage measuring module, and the transfer function of which is
A third generating unit for generating
Generating a d-axis component E of a voltage correction signaldctrl；
A fourth generating unit, the input end of which is connected with the output end of the terminal voltage measuring module and the transfer function of which is
A fourth generating unit for generating
Generating a q-axis component E of a voltage correction signalqctrl；
A third amplitude limiter, the input end of which is connected with the output ends of the third generation unit and the fourth generation unit, and the output end of which is used as the output end of the voltage correction signal generation module and is used for correcting the d-axis component E of the voltage correction signaldctrlAnd q-axis component EqctrlCarrying out amplitude limiting operation;
wherein, is Δ VdAnd Δ VqRespectively represent VdAnd VqThe amount of change in (c); k is a radical of7～k10For the gain parameter, s is the differential operator.
Generally, by the above technical solution conceived by the present invention, the following beneficial effects can be obtained:
(1) when the voltage of the direct-drive fan terminal rises, voltage correction signals are generated by using the change indexes of the voltage of the direct-drive fan terminal, namely, the change quantity, the change rate and the like, and are attached to the output end of a PI (proportional integral) controller in the current control link of the direct-drive fan grid-side converter, d-axis and q-axis components of the equivalent internal potential of the direct-drive fan output by the PI controller are corrected, so that the equivalent power output voltage of the direct-drive fan can be reduced, the transient overvoltage of the direct-drive fan is restrained, and the safe operation of a power.
(2) The additional control method provided by the invention only responds to the situation that the terminal voltage rises, but does not act when the terminal voltage is unchanged or falls, and can not influence the normal control of the direct-drive fan under the situation of ensuring the suppression of transient overvoltage.
Drawings
FIG. 1 is a schematic control diagram of a conventional direct-drive fan grid-side converter generating an equivalent internal potential;
fig. 2 is a flowchart of an additional control method for suppressing transient overvoltage of a direct drive fan according to an embodiment of the present invention;
fig. 3 is an additional control schematic diagram for suppressing transient overvoltage of the direct drive wind turbine according to the embodiment of the present invention;
FIG. 4 is a schematic diagram of another additional control system for suppressing transient overvoltage of a direct drive wind turbine according to an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of an electric power system including a direct drive fan according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of additional control of a direct drive fan provided by an embodiment of the present invention;
FIG. 7 is a diagram illustrating additional control results of a direct-drive fan according to an embodiment of the present invention;
the same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:
1. 2 is a synchronous generator set, 3 is a direct-drive wind power plant equivalent to one direct-drive fan, 4 and 5 are power generation equipment grid-connected transformers, 6 and 7 are loads, and 8-11 are pi-shaped equivalent circuits.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
In the present application, the terms "first," "second," and the like (if any) in the description and the drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
Before explaining the technical scheme of the present invention in detail, a brief introduction is first made to the principle that the existing direct-drive wind turbine grid-side converter generates the equivalent internal potential, as shown in fig. 1, the existing current controller includes two branches, which are respectively used for generating d-axis and q-axis components of the equivalent internal potential, and the control of the d-axis control branch specifically is as follows: collecting d-axis current i of direct-drive fandIs compared with d-axis current reference value idrAfter difference is made, PI control is carried out to obtain a d-axis voltage reference value Ed(ii) a The control of the q-axis control branch is specifically as follows: collecting q-axis current i of direct-drive fanqIs compared with a q-axis current reference value iqrAfter difference is made, PI control is carried out to obtain a q-axis voltage reference value Eq(ii) a Then d-axis voltage reference value E is converted by coordinatesdAnd q-axis voltage reference value EqAnd converting the voltage into the output voltage of the equivalent power supply of the direct-drive fan.
Aiming at the technical problem that the prior feedforward control can not inhibit the transient overvoltage of the direct-drive fan and can not ensure the safe operation of a power system, the invention provides an additional control method and an additional control system for inhibiting the transient overvoltage of the direct-drive fan, and the overall thought is as follows: the method comprises the steps that a control signal is generated by utilizing the terminal voltage of the direct-drive fan and change information of the terminal voltage, the control signal is enabled to respond to the situation that the terminal voltage rises and does not act when the terminal voltage is unchanged or falls, and when the terminal voltage of a system rises, a corresponding voltage correction signal is generated based on the change situation of the terminal voltage and is added to a terminal voltage feedforward control branch of a direct-drive fan network side converter, the output voltage of an equivalent voltage source of the direct-drive fan is reduced, and therefore transient overvoltage is restrained. The idea is derived from the idea of additional damping, namely when the terminal voltage of the direct-drive fan is increased, the starting module is controlled to drive additional control action, and a damping signal is added to control an equivalent voltage source of the fan to reduce voltage output, so that transient overvoltage is suppressed. The following are examples.
Example 1:
an additional control method for suppressing transient overvoltage of a direct-drive wind turbine is shown in fig. 2 and comprises the following steps:
when the voltage of the end of the direct-drive fan rises, generating a voltage correction signal according to the change index of the end voltage, adding the voltage correction signal to the output end of a PI (proportional integral) controller in the current control link of the grid-side converter of the direct-drive fan, and correcting d and q axis components of equivalent internal potential of the direct-drive fan output by the PI controller so as to reduce the output voltage of an equivalent power supply of the direct-drive fan and inhibit the transient overvoltage of the direct-drive fan;
it is easy to understand that in order to reduce the equivalent power output voltage of the direct-drive fan after the voltage correction signal is added, in the invention, both the d-axis component and the q-axis component of the generated voltage correction signal should be negative values;
in practical application, whether the voltage of the direct-drive fan terminal rises or not can be judged according to the variable quantity or the variable rate of the terminal voltage; as an optional implementation manner, in this embodiment, it is specifically determined whether the voltage across the direct drive fan increases according to the voltage variation, and the specific determination manner is as follows:
if Δ V>Tsd1Judging that the voltage of the direct-drive fan terminal rises;
wherein V represents the terminal voltage of the direct-drive fan, Δ V represents the variation of the terminal voltage of the direct-drive fan, and Tsd1The judgment threshold value is a parameter which is larger than 0; it should be noted that the present invention is only an alternative embodiment, and should not be construed as the only limitation of the present invention; for example, in some other embodiments of the present invention, the specific manner for determining the voltage rise of the direct drive fan terminal is as follows: if it is
The voltage of the direct drive fan terminal is judged to rise,
representing the rate of change of the terminal voltage of the direct drive wind turbine, Tsd2The judged threshold value is a parameter which is larger than 0;
in the invention, the change index of the terminal voltage can be the change amount of the terminal voltage or the change rate of the terminal voltage;
the specific mode of generating the voltage correction signal according to the change index of the terminal voltage is as follows: executing one or more operations of gain, filtering and differentiation on the change index of the terminal voltage to generate a voltage correction signal;
as an optional implementation manner, in this embodiment, the index of change of the terminal voltage is the amount of change of the terminal voltage, and the specific manner of generating the voltage correction signal is as follows:
according to Edctrl＝k1ΔVd、Eqctrl＝k2ΔVqRespectively generating d-axis components E of the voltage correction signalsdctrlAnd q-axis component Eqctrl；k1And k2Is a gain parameter, s is a differential operator; gain parameter k1And k2The direct-drive fan can be set according to the parameters of the direct-drive fan;
it is easy to understand that, in this embodiment, the voltage correction signal is added to the output end of the PI controller in the current control link of the grid-side converter of the direct-drive wind turbine, specifically, the d-axis component E of the voltage correction signal is addeddctrlAdding the q-axis component E of the voltage correction signal to the d-axis branch of the PI controller outputqctrlAdded to the q-axis branch of the PI controller output.
Example 2:
an additional control method for suppressing transient overvoltage of a direct-drive wind turbine is similar to that in embodiment 1, except that in this embodiment, the change index of the terminal voltage is a change rate of the terminal voltage, and the specific manner of generating the voltage correction signal is as follows:
according to
Respectively generating d-axis components E of the voltage correction signalsdctrlAnd q-axis component Eqctrl；
Wherein the content of the first and second substances,
and
respectively represent VdAnd VqThe rate of change of (c); k is a radical of3～k6For the gain parameter, s is the differential operator.
Example 3:
an additional control method for suppressing transient overvoltage of a direct-drive wind turbine is similar to that in embodiment 1, except that in this embodiment, the index of change of the terminal voltage is the amount of change of the terminal voltage, and the specific way of generating the voltage correction signal is as follows:
or, according to
Respectively generating d-axis components E of the voltage correction signalsdctrlAnd q-axis component Eqctrl；
Wherein, is Δ VdAnd Δ VqRespectively represent VdAnd VqThe amount of change in (c); k is a radical of7～k10For the gain parameter, s is the differential operator.
Example 4:
an additional control system for suppressing transient overvoltage of a direct drive wind turbine is shown in fig. 3 and comprises: the terminal voltage measuring module, the control starting module, the voltage correction signal generating module and the terminal voltage response optimizing module;
the terminal voltage measuring module is connected with the output end of the direct-drive fan and is used for measuring the terminal voltage V of the direct-drive fan, and/or the terminal voltage variation rate, and the d-axis component V of the terminal voltage of the direct-drive fandAnd q-axis component Vq；
The input end of the control starting module is connected with the output end of the terminal voltage measuring module and is used for judging whether the terminal voltage of the direct-drive fan rises or not according to the measuring result of the terminal voltage measuring module and generating a corresponding control starting signal; when the end voltage of the starting signal rises, the voltage correction signal generation module is indicated to start working; when the terminal voltage of the control starting signal is reduced or maintained unchanged, indicating that the voltage correction signal generation module does not work;
the input end of the voltage correction signal generation module is connected with the control starting module and the output end of the terminal voltage measurement module, and the voltage correction signal generation module is used for generating a voltage correction signal according to the change index of the terminal voltage when the control starting module indicates that the voltage correction signal generation module starts to work;
the terminal voltage response optimization module is connected with a first input end of the voltage correction signal generation module and a second input end of the terminal voltage response optimization module is connected with an output end of a PI (proportional integral) controller in a direct-drive fan grid-side converter current control link, and is used for attaching the voltage correction signal as a feedforward control signal to the output end of the PI controller in the direct-drive fan grid-side converter current control link, correcting d-axis and q-axis components of equivalent internal potential of a direct-drive fan output by the PI controller, reducing equivalent power supply output voltage of the direct-drive fan and inhibiting transient overvoltage of the direct-drive fan; as shown in fig. 3, in this embodiment, the terminal voltage response optimization module is specifically composed of two adders, one of the adders is configured to correct a d-axis component of the direct-drive fan equivalent internal potential output by the PI controller by using a d-axis component of the voltage correction signal, the other adder is configured to correct a q-axis component of the direct-drive fan equivalent internal potential output by the PI controller by using a q-axis component of the voltage correction signal, and output ends of the two adders are connected to the coordinate transformation unit of the current controller.
Example 5:
an additional control system for suppressing transient overvoltage of a direct-drive wind turbine is similar to that of embodiment 4, except that in this embodiment, the voltage correction signal generation module includes: a first gain amplifier, a second gain amplifier and a first limiter;
a first gain amplifier having an input connected to the input and the output of the terminal voltage measuring module, and arranged according to Edctrl＝k1ΔVdGenerating a d-axis component E of a voltage correction signaldctrl；
A second gain amplifier having an input connected to the input and the output of the terminal voltage measuring module, and arranged to operate according to Eqctrl＝k2ΔVqGenerated voltage correctionQ-axis component E of the signalqctrl；
A first amplitude limiter, whose input end is connected with the output ends of the first gain amplifier and the second gain amplifier, and whose output end is used as the output end of the voltage correction signal generation module, which is used for the d-axis component E of the voltage correction signaldctrlAnd q-axis component EqctrlCarrying out amplitude limiting operation;
wherein, is Δ VdAnd Δ VqRespectively represent VdAnd VqThe amount of change in (c); k is a radical of1And k2For the gain parameter, s is the differential operator.
Example 6:
an additional control system for suppressing transient overvoltage of a direct drive fan is similar to that in embodiment 4, except that, as shown in fig. 4, in this embodiment, a voltage correction signal generation module includes: a first generating unit, a second generating unit and a second slicer;
a first generating unit, the input end of which is connected with the output end of the terminal voltage measuring module, and the transfer function of which is
A first generating unit for generating
Generating a d-axis component E of a voltage correction signaldctrl(ii) a As shown in fig. 4, in the present embodiment, the first generation unit is constituted by a filter, a differentiator and a gain amplifier connected in this order;
a second generating unit, the input end of which is connected with the output end of the terminal voltage measuring module and the transfer function of which is
A second generating unit for generating
Generating a q-axis component E of a voltage correction signalqctrl(ii) a As shown in FIG. 4, in the present embodiment, the second generating units are connected in sequenceThe filter, the differentiator and the gain amplifier;
a second amplitude limiter, whose input end is connected with the output ends of the first and second generating units, and whose output end is used as the output end of the voltage correction signal generating module, and is used for correcting the d-axis component E of the voltage correction signaldctrlAnd q-axis component EqctrlCarrying out amplitude limiting operation;
wherein the content of the first and second substances,
and
respectively represent VdAnd VqThe rate of change of (c); k is a radical of3～k6For the gain parameter, s is the differential operator.
Example 7:
an additional control system for suppressing transient overvoltage of a direct-drive wind turbine is similar to that of embodiment 4, except that in this embodiment, the voltage correction signal generation module includes: a third generation unit, a fourth generation unit and a third limiter;
a third generating unit, the input end of which is connected with the output end of the terminal voltage measuring module, and the transfer function of which is
A third generating unit for generating
Generating a d-axis component E of a voltage correction signaldctrl(ii) a Optionally, in this embodiment, the third generating unit is composed of a filter, a differentiator and a gain amplifier, which are connected in sequence;
a fourth generating unit, the input end of which is connected with the output end of the terminal voltage measuring module and the transfer function of which is
A fourth generating unit for generating
Generating a q-axis component E of a voltage correction signalqctrl(ii) a Optionally, in this embodiment, the fourth generating unit is composed of a filter, a differentiator and a gain amplifier, which are connected in sequence;
a third amplitude limiter, the input end of which is connected with the output ends of the third generation unit and the fourth generation unit, and the output end of which is used as the output end of the voltage correction signal generation module and is used for correcting the d-axis component E of the voltage correction signaldctrlAnd q-axis component EqctrlCarrying out amplitude limiting operation;
wherein, is Δ VdAnd Δ VqRespectively represent VdAnd VqThe amount of change in (c); k is a radical of7～k10For the gain parameter, s is the differential operator.
The technical solution of the present invention is further explained with reference to the specific application scenario shown in fig. 5. FIG. 5 is a schematic structural diagram of a three-level system applied to a wind farm with direct drive in any of the embodiments, and the practical application is not limited to the structure and the parameters; in fig. 5, 1 and 2 are synchronous generator sets, 3 is a direct-drive wind power plant equivalent to a direct-drive fan, 4 to 5 are power generation equipment grid-connected transformers, 6 to 7 are load 1 and load 2, and 8 to 11 are pi-type equivalent circuits.
As shown in fig. 6, a coordinate system shown by dq axis in the figure is a phase-locked coordinate system at a phase-locked speed, and when the system operates stably, the voltage U at the direct-drive fan end is U0Coincident with d-axis, internal potential E0Included angle delta with d axis0. When the system has a three-phase grounding short circuit fault, the voltage of the terminal of the direct-drive fan is over-voltage from the initial U0Move to U1The equivalent internal potential is formed by the initial E0Move to E1Internal potential E1Included angle delta with d axis1. After the overvoltage occurs, the additional control system judges the increase of the terminal voltage by acquiring the information of the terminal voltage change delta E and the change rate dE/dt thereof, so that the additional control system is driven to act. Additional control generates an additional control signal through the change rate of the dq-axis voltage, and the additional control signal is added to the output end of a PI controller in the current control link of the network side converter to correct the PI controlD and q axis components of equivalent internal potential of the direct-drive fan output by the device are used for reducing the output voltage of the equivalent voltage source of the direct-drive fan to Ec，EcIncluded angle delta with d axisc. Thereby suppressing the overvoltage of the terminal voltage to be reduced to Uc。
Fig. 7 is a variation curve of the wind turbine end voltage in the dynamic process when the direct-drive fan additional control is added and the direct-drive fan additional control is not added. Where the disturbance is a three-phase short-to-ground fault at 5s load 6 and is cut off at 5.1 s. It can be seen that the additional control proposed by the present invention can effectively suppress the transient overvoltage. It should be noted that by changing the control parameters, different response rates and effects can be achieved.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (8)
1. An additional control method for suppressing transient overvoltage of a direct-drive fan is characterized by comprising the following steps:
when the voltage of the direct-drive fan terminal rises, a voltage correction signal is generated according to the change index of the terminal voltage, the voltage correction signal is added to the output end of a PI (proportional integral) controller in the current control link of the direct-drive fan grid-side converter as a feedforward control signal, and d and q axis components of equivalent internal potential of the direct-drive fan output by the PI controller are corrected to reduce the output voltage of an equivalent power supply, so that the transient overvoltage of the direct-drive fan is restrained.
2. The additional control method for suppressing the transient overvoltage of the direct drive wind turbine as claimed in claim 1, wherein the manner of judging whether the voltage of the direct drive wind turbine rises comprises:
if Δ V > Tsd1Judging that the voltage of the direct-drive fan terminal rises;
or
Judging that the voltage of the direct drive fan terminal rises;
v represents the terminal voltage of the direct-drive fan, and delta V represents the variation of the terminal voltage of the direct-drive fan;
represents the rate of change of terminal voltage V; tsd1And Tsd2Indicates the judgment threshold value, and Tsd1>0，Tsd2>0。
3. An additional control method for suppressing transient overvoltage of direct drive wind turbine as claimed in claim 1 or 2, wherein the change index of the terminal voltage is the change amount of the terminal voltage or the change rate of the terminal voltage;
the specific mode for generating the voltage correction signal according to the change index of the terminal voltage is as follows:
and executing one or more operations of gain, filtering and differentiation on the change index of the terminal voltage to generate the voltage correction signal.
4. An additional control method for suppressing transient overvoltage of direct drive wind turbine as set forth in claim 3, wherein said voltage correction signal is generated by performing one or more of gain, filtering and differentiation on said voltage variation indicator, comprising:
according to Edctrl＝k1ΔVd、Eqctrl＝k2ΔVqGenerating d-axis components E of the voltage correction signals, respectivelydctrlAnd q-axis component Eqctrl；
Or, according to
Generating d-axis components E of the voltage correction signals, respectivelydctrlAnd q-axis component Eqctrl；
Or, according to
Generating d-axis components E of the voltage correction signals, respectivelydctrlAnd q-axis component Eqctrl；
V represents the terminal voltage of the direct-drive fan, and delta V represents the variation of the terminal voltage of the direct-drive fan; vdAnd VqRespectively representing d-axis component and q-axis component, delta V, of terminal voltage of the direct-drive fan under a phase-locked coordinate systemdAnd Δ VqRespectively represent VdAnd VqThe amount of change in (c);
and
respectively represent VdAnd VqThe rate of change of (c); k is a radical of1And k2As a gain parameter, k3～k10For the filter parameters, s is the differential operator.
5. An additional control system for suppressing transient overvoltage of a direct drive wind turbine, comprising: the terminal voltage measuring module, the control starting module, the voltage correction signal generating module and the terminal voltage response optimizing module;
the terminal voltage measuring module is connected with the output end of the direct-drive fan and is used for measuring the terminal voltage V of the direct-drive fan and/or the terminal voltage variation rate and the d-axis component V of the terminal voltage of the direct-drive fandAnd q-axis component Vq；
The input end of the control starting module is connected with the output end of the terminal voltage measuring module, and the control starting module is used for judging whether the terminal voltage of the direct-drive fan rises or not according to the measuring result of the terminal voltage measuring module and generating a corresponding control starting signal; when the terminal voltage rises, the control starting signal indicates the voltage correction signal generation module to start working; when the terminal voltage is reduced or maintained unchanged, the control starting signal indicates that the voltage correction signal generation module does not work;
the input end of the voltage correction signal generation module is connected with the output ends of the control starting module and the terminal voltage measurement module, and the voltage correction signal generation module is used for generating a voltage correction signal according to the change index of the terminal voltage when the control starting module indicates that the voltage correction signal generation module starts to work;
and a first input end of the terminal voltage response optimization module is connected with an output end of the voltage correction signal generation module, a second input end of the terminal voltage response optimization module is connected with an output end of a PI (proportional integral) controller in a direct-drive fan grid-side converter current control link, and the terminal voltage response optimization module is used for adding the voltage correction signal as a feedforward control signal to the output end of the PI controller in the direct-drive fan grid-side converter current control link, correcting d-axis and q-axis components of equivalent internal potential of a direct-drive fan output by the PI controller, reducing equivalent power supply output voltage of the direct-drive fan and inhibiting transient overvoltage of the direct-drive fan.
6. The additional control system for suppressing transient overvoltage of direct drive wind turbine as set forth in claim 5, wherein said voltage correction signal generating module comprises: a first gain amplifier, a second gain amplifier and a first limiter;
the input end of the first gain amplifier is connected with the input end and the output end of the terminal voltage measuring module, and the first gain amplifier is used for measuring the terminal voltage according to the Edctrl＝k1ΔVdGenerating a d-axis component E of the voltage correction signaldctrl；
The input end of the second gain amplifier is connected with the input end and the output end of the terminal voltage measuring module, and the second gain amplifier is used for measuring the terminal voltage according to the Eqctrl＝k2ΔVqGenerating a q-axis component E of the voltage correction signalqctrl；
The input end of the first amplitude limiter is connected with the output ends of the first gain amplifier and the second gain amplifier, the output end of the first amplitude limiter is used as the output end of the voltage correction signal generation module, and the first amplitude limiter is used for comparing the voltage with the voltageD-axis component E of the voltage correction signaldctrlAnd q-axis component EqctrlCarrying out amplitude limiting operation;
wherein, is Δ VdAnd Δ VqRespectively represent VdAnd VqThe amount of change in (c); k is a radical of1And k2For the gain parameter, s is the differential operator.
7. The additional control system for suppressing transient overvoltage of direct drive wind turbine as set forth in claim 5, wherein said voltage correction signal generating module comprises: a first generating unit, a second generating unit and a second slicer;
the input end of the first generating unit is connected with the output end of the terminal voltage measuring module, and the transfer function of the first generating unit is
The first generating unit is used for generating
Generating a d-axis component E of the voltage correction signaldctrl；
The input end of the second generating unit is connected with the output end of the terminal voltage measuring module, and the transfer function of the second generating unit is
The second generating unit is used for generating
Generating a q-axis component E of the voltage correction signalqctrl；
The input end of the second amplitude limiter is connected with the output ends of the first generating unit and the second generating unit, the output end of the second amplitude limiter is used as the output end of the voltage correction signal generating module, and the second amplitude limiter is used for correcting the voltage correction signalD-axis component E ofdctrlAnd q-axis component EqctrlCarrying out amplitude limiting operation;
wherein the content of the first and second substances,
and
respectively represent VdAnd VqThe rate of change of (c); k is a radical of3～k6For the gain parameter, s is the differential operator.
8. The additional control system for suppressing transient overvoltage of direct drive wind turbine as set forth in claim 5, wherein said voltage correction signal generating module comprises: a third generation unit, a fourth generation unit and a third limiter;
the input end of the third generating unit is connected with the output end of the terminal voltage measuring module, and the transfer function of the third generating unit is
The third generating unit is used for generating
Generating a d-axis component E of the voltage correction signaldctrl；
The input end of the fourth generating unit is connected with the output end of the terminal voltage measuring module, and the transfer function of the fourth generating unit is
The fourth generating unit is used for generating
Generating a q-axis component E of the voltage correction signalqctrl；
The input end of the third amplitude limiter is connected with the output ends of the third generation unit and the fourth generation unit, and the output end of the third amplitude limiter is connected with the output ends of the fourth generation unit and the fourth generation unitThe output end of the output end is used as the output end of the voltage correction signal generation module and is used for correcting the d-axis component E of the voltage correction signaldctrlAnd q-axis component EqctrlCarrying out amplitude limiting operation;
wherein, is Δ VdAnd Δ VqRespectively represent VdAnd VqThe amount of change in (c); k is a radical of7～k10For the gain parameter, s is the differential operator.
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| CN113224795A (en) * | 2021-05-31 | 2021-08-06 | 重庆大学 | Wind power grid-connected system transient stability control method based on automatic voltage regulation |
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