CN107147141B - Inverter control method and device of wind generating set - Google Patents
Inverter control method and device of wind generating set Download PDFInfo
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- CN107147141B CN107147141B CN201710262445.0A CN201710262445A CN107147141B CN 107147141 B CN107147141 B CN 107147141B CN 201710262445 A CN201710262445 A CN 201710262445A CN 107147141 B CN107147141 B CN 107147141B
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Abstract
The embodiment of the invention provides a method and a device for controlling an inverter of a wind generating set. The inverter control method includes: if the detected grid voltage is smaller than the first voltage threshold value, determining that a grid-side inverter of the wind generating set enters a low-voltage ride-through state; and if the grid-side inverter is in a low voltage ride through state and the grid voltage is detected to be increased to be larger than a second voltage threshold value, the working current limit value of the grid-side inverter is controlled to be gradually increased, wherein the second voltage threshold value is larger than the first voltage threshold value. By adopting the scheme, the power value of the grid-side inverter can be limited by controlling the working current limit value of the grid-side inverter to be gradually increased, so that the problem of direct-current bus overvoltage caused by the fact that the grid-side inverter absorbs power of a power grid from the power grid is solved.
Description
Technical Field
The invention relates to the technical field of wind power generation, in particular to a method and a device for controlling an inverter of a wind generating set.
Background
In the operation process of the wind generating set, when the voltage value of the power grid drops below 1P.U (Per Unit Per Unit) instantly due to disturbance or fault of the power grid, the control system of the wind generating set can realize uninterrupted grid-connected operation during the voltage fault of the power grid by adjusting a control strategy. Wherein a converter of the wind power plant performs a main low voltage ride through control. In the existing low-voltage ride-through control strategy, when a power grid fault is eliminated, the power grid is in a low-voltage ride-through recovery state, the active power of a converter is generally not limited, and the full-power operation of the converter is controlled.
However, the phase angle and frequency of the grid voltage at this time may still change greatly, and the grid-side inverter may have an unstable operating state due to an excessively large operating power, and may change from an inverted power state to an absorbed power state in a severe case. Moreover, the machine-side rectifier also injects active power into the dc bus, so that the dc bus absorbs excessive active power, and when the braking unit cannot discharge excessive energy on the dc bus due to overload, the dc bus voltage exceeds the maximum working voltage, so that device failure is caused, the maintenance cost of the wind turbine generator system is increased, and low-voltage ride-through failure may also be caused.
Disclosure of Invention
The embodiment of the invention provides a method and a device for controlling an inverter of a wind generating set, which aim to solve the problem of overvoltage of a direct-current bus caused by the fact that a grid-side inverter easily absorbs active power from a power grid when low-voltage ride-through is recovered in the prior art.
In order to achieve the above object, an embodiment of the present invention provides an inverter control method for a wind turbine generator system, including: if the detected grid voltage is smaller than the first voltage threshold value, determining that a grid-side inverter of the wind generating set enters a low-voltage ride-through state; controlling the operating current limit of the grid-side inverter to gradually increase if the grid-side inverter is already in the low voltage ride through state and an increase in grid voltage greater than a second voltage threshold is detected, wherein the second voltage threshold is greater than the first voltage threshold.
Optionally, the gradually increasing of the operating current limit of the grid-side inverter includes: the active current limit value and the reactive current limit value of the control network side inverter are gradually increased; and/or gradually increasing the active power limit value and the reactive power limit value of the control network side inverter.
Optionally, the gradually increasing of the operating current limit of the grid-side inverter includes: the operating current limit of the control grid side inverter increases linearly with time.
Optionally, the inverter control method further includes: and when the working current limit value of the grid-side inverter is increased to the maximum working current of the grid-side inverter, setting the maximum working current as the working current limit value of the grid-side inverter.
Optionally, after the if the detected grid voltage is less than the first voltage threshold, the method further includes: and controlling the grid-side inverter to switch from performing active current priority control to performing reactive current priority control.
Optionally, the inverter control method further includes: when the grid voltage is detected to be increased to be larger than a second voltage threshold value, controlling the grid-side inverter to switch from performing reactive current priority control to performing active current priority control; or when the working current limit value of the grid-side inverter is increased to the maximum working current of the grid-side inverter, controlling the grid-side inverter to switch from executing reactive current priority control to executing active current priority control.
Optionally, the inverter control method further includes: and when detecting that the voltage of the direct current bus is greater than a preset discharge voltage threshold value, controlling a brake unit of the wind generating set to discharge the energy of the direct current bus.
According to another aspect of the present invention, an embodiment of the present invention also provides an inverter control apparatus of a wind turbine generator system, including: the detection module is used for determining that a grid-side inverter of the wind generating set enters a low voltage ride through state if the grid voltage is detected to be smaller than a first voltage threshold; the first control module is used for controlling the working current limit value of the grid-side inverter to be gradually increased if the grid-side inverter is in the low voltage ride through state and the grid voltage is detected to be increased to be larger than a second voltage threshold value, wherein the second voltage threshold value is larger than the first voltage threshold value.
Optionally, the first control module is configured to control an active current limit and a reactive current limit of the grid-side inverter to gradually increase; and/or gradually increasing the active power limit value and the reactive power limit value of the control network side inverter.
Optionally, the first control module is configured to: the operating current limit of the control grid side inverter increases linearly with time.
Optionally, the first control module is further configured to: and when the working current limit value of the grid-side inverter is increased to the maximum working current of the grid-side inverter, setting the maximum working current as the working current limit value of the grid-side inverter.
Optionally, the inverter control device further includes: and the second control module is used for controlling the grid-side inverter to switch from performing active current priority control to performing reactive current priority control if the grid voltage is detected to be smaller than the first voltage threshold.
Optionally, the inverter control device further includes: the third control module is used for controlling the grid-side inverter to switch from the reactive current priority control to the active current priority control when the grid voltage is detected to be increased to be larger than the second voltage threshold; or, the controller is configured to control the grid-side inverter to switch from performing reactive current priority control to performing active current priority control when the operating current limit of the grid-side inverter is increased to the maximum operating current of the grid-side inverter.
Optionally, the inverter control device further includes: and the fourth control module is used for controlling the brake unit of the wind generating set to release the energy of the direct current bus when detecting that the voltage of the direct current bus is greater than a preset release voltage threshold value.
According to the inverter control scheme of the wind generating set, whether a grid-side inverter of the wind generating set enters a low voltage ride through state is determined by detecting whether the grid voltage is too small, the grid voltage is continuously detected in the low voltage ride through state, and when the grid voltage is increased to a normal state, the working current limit value of the grid-side inverter is controlled to be gradually increased so as to achieve the purpose of limiting the power value of the grid-side inverter, so that the problem of overvoltage of a direct current bus caused by the fact that the grid-side inverter absorbs the power of a grid from the grid is solved, the problem of device failure is further avoided, and the maintenance cost of the wind generating set is reduced.
Drawings
Fig. 1 is a flowchart of an inverter control method of a wind turbine generator system according to a first embodiment of the present invention;
fig. 2 is a flowchart of an inverter control method of a wind turbine generator system according to a second embodiment of the present invention;
fig. 3 is a grid voltage droop curve and a current limit control curve provided by an inverter control method of a wind generating set according to a second embodiment of the present invention;
fig. 4 is a block diagram showing a configuration of an inverter control device of a wind turbine generator system according to a third embodiment of the present invention.
Detailed Description
The inverter control method, device and device of the wind generating set according to the embodiments of the present invention are described in detail below with reference to the accompanying drawings (like numbers in several figures denote like elements). The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
Example one
Fig. 1 is a flowchart of an inverter control method of a wind turbine generator system according to a first embodiment of the present invention.
As shown in fig. 1, the inverter control method of the wind turbine generator system of the present embodiment includes:
s110, if the grid voltage is detected to be smaller than the first voltage threshold value, the grid-side inverter of the wind generating set is determined to enter a low voltage ride through state.
The first voltage threshold is used for judging whether the power grid voltage falls to a lower area where the power grid voltage signal has large fluctuation and is easy to distort, and when the power grid voltage is smaller than the first voltage threshold, the power grid can be determined to have a fault. The first voltage threshold can be in a range of 0-1 P.U. The first voltage threshold may be determined according to an empirical value of the actual low voltage ride through control, or may be determined by combining experimental data obtained by simulation calculation. For example, the first voltage threshold may be 0.88 P.U.
During the operation of the wind generating set, a grid-connected voltage signal of the wind generating set can be periodically detected by arranging a voltage detection device (for example, a voltage sensor) at a grid-connected point, and the grid voltage is processed by a voltage processing device. When the grid voltage is detected to be smaller than the first voltage threshold value, the grid is determined to have a fault, and then the grid-side converter of the wind generating set is determined to enter a low-voltage ride-through state. In order to ensure that the wind generating set does not run off the grid, low-voltage ride-through control is executed on the wind generating set, and the low-voltage ride-through control comprises the step of switching active current priority control executed by a grid-side inverter in a normal working state into reactive current priority control in a low-voltage ride-through state.
And S120, if the grid-side inverter is in a low voltage ride through state and the grid voltage is detected to be increased to be larger than a second voltage threshold value, controlling the working current limit value of the grid-side inverter to be gradually increased.
Wherein the second voltage threshold is greater than the first voltage threshold. The second voltage threshold is used for judging whether the power grid voltage is increased to a normal interval in which the power grid voltage signal has small fluctuation and is not distorted. The second voltage threshold is greater than the first voltage threshold, and the value range of the first voltage threshold can be 0-1 P.U. For example, the first voltage threshold may be 0.88P.U and the second voltage threshold may be 0.92 P.U.
When the grid-side inverter is in a low voltage ride through state, whether the grid voltage value is increased from being smaller than a first voltage threshold value to being larger than a second voltage threshold value or not is continuously detected. And when the grid voltage is detected to be increased to be larger than the second voltage threshold value, the low voltage ride through is in a recovery state, and the working current limit value of the grid-side inverter is controlled to be gradually increased. The working current limit value is an upper limit value of the current working current of the grid-side inverter, and can be used for performing amplitude limiting processing on the working current of the grid-side inverter, namely, performing amplitude limiting processing on the working current of the grid-side inverter by using the gradually increased working current limit value. For example, the operating current limit of the grid-side inverter is controlled to gradually increase by sending an instruction carrying a given value of the operating current limit to the grid-side inverter in real time.
In the process of controlling the working current limit value of the grid-side inverter to be gradually increased, even if the grid-side inverter absorbs active power from the grid side, the power value of the grid-side inverter is still in a controllable state, so that the power absorbed by the direct-current bus is limited and cannot easily exceed the maximum working voltage of the direct-current bus, the problem of overvoltage of the direct-current bus caused by the fact that the grid-side inverter absorbs a large amount of active power is fundamentally avoided, the success rate of low-voltage ride through is further improved, and the stability of the grid is ensured.
In an optional embodiment, the time is counted from the time when the grid voltage is detected to increase to the second voltage threshold, the working current limit value corresponding to the grid-side inverter at the time is set to zero, and the working current limit value of the grid-side inverter is controlled to gradually increase with time.
According to the inverter control method of the wind generating set, whether the grid-side inverter of the wind generating set enters the low voltage ride through state is determined by detecting whether the grid voltage is too small, the grid voltage is continuously detected in the low voltage ride through state, and when the grid voltage is increased to the normal state, the working current limit value of the grid-side inverter is controlled to be gradually increased so as to achieve the purpose of limiting the power value of the grid-side inverter, so that the problem of overvoltage of a direct current bus caused by the fact that the grid-side inverter absorbs power from a power grid is solved, the problem of device failure is further avoided, and the maintenance cost of the wind generating set is reduced.
The inverter control method of the wind turbine generator system according to the present embodiment may be performed by a control device such as a converter controller and a grid-side inverter controller of the wind turbine generator system. However, it should be understood by those skilled in the art that in practical applications, any other device having corresponding data acquisition and processing functions may be used to implement the inverter control method of the wind turbine generator system according to the present embodiment.
Example two
Fig. 2 is a flowchart of an inverter control method of a wind turbine generator system according to a second embodiment of the present invention, which can be regarded as an alternative implementation of the inverter control method of the wind turbine generator system according to the first embodiment.
The main executing body of the inverter control method of the wind generating set of the embodiment can be any device with corresponding data acquisition and processing functions. Including, but not limited to, a converter controller of the wind turbine generator system, a grid-side inverter controller, and a controller independent of the converter controller and the grid-side inverter controller.
As shown in fig. 2, the inverter control method of the wind turbine generator system of the present embodiment includes:
and S210, judging whether the power grid voltage is smaller than a first voltage threshold value.
The first voltage threshold is used for judging whether the power grid fails, and when the power grid voltage is smaller than the first voltage threshold, it can be determined that the power grid voltage falls to a lower area due to the fact that the power grid fails.
In the operation process of the wind generating set, the grid voltage can be detected by arranging a voltage sensor at a grid connection point, and whether the detected grid voltage falls to a first voltage threshold value is judged. If the detected grid voltage is greater than the first voltage threshold, it is determined that the grid voltage does not drop to a lower area, and the wind generating set is still in a normal operation state, at this time, step S260 is executed, and the grid-side inverter is controlled to continue to operate normally. If the detected grid voltage is smaller than (or equal to) the first voltage threshold, it is determined that the grid voltage falls to a lower area, and at this time, step S220 is executed to ensure that the wind generating set does not operate in a grid.
And S220, determining that the grid-side inverter enters a low voltage ride through state, and controlling the grid-side inverter to execute reactive current priority control.
In this embodiment, in the normal operation process of the wind turbine generator system, the grid-side inverter performs active current priority control to increase grid-connected power of the wind turbine generator system. When the grid voltage is detected to drop to be smaller than the first voltage threshold value, the grid-side inverter of the wind driven generator unit is determined to enter a low voltage ride through state, and the grid-side inverter is controlled to execute reactive current priority control.
In an alternative embodiment, when it is detected that the grid voltage value is smaller than the first voltage threshold value, the external reactive power setting (for example, a reactive power setting to a remote controller) is cancelled, a reactive current set value at that time is calculated, and the grid-side inverter is controlled to switch from performing active current limited control to performing reactive current priority control. Specifically, firstly, a reactive current set value I is calculated according to a reactive current rule during fault ride-through a reactive current controller in the wind generating setq_refAnd judging the given value I of the reactive currentq_refWhether or not it is greater than the maximum current limit Imax1. If Iq_refIs greater than Imax1Then I will beq_refIs modified to Imax1. If Iq_refIs less than or equal toIs equal to Imax1Then I is not modifiedq_ref. Then, obtaining an active current given value I through a direct current bus outer ring controller (PI regulator) in the wind generating setd_refAnd judging the given value I of the active currentd_refWhether or not to satisfy
If so, not modifying Id_ref(ii) a If not, then Id_refIs modified into
Finally, determining Iq_refAnd Id_refAnd the grid-side inverter control algorithm is used for generating a gate switching signal for controlling the IGBT of the grid-side inverter. Wherein, Imax1The maximum current limit value is the maximum current limit value of the grid-side inverter and is used for carrying out amplitude limiting processing on the working current of the grid-side inverter. I ismax1Less than or equal to the maximum working current I of the grid-side invertermax(Here, the maximum operating current I is illustratedmaxCan be the maximum sustainable operating current that the grid-side inverter can withstand, and/or the maximum short-time sustainable operating current that the grid-side inverter can withstand, and
and S230, judging whether the power grid voltage is greater than a second voltage threshold value.
As shown in fig. 3, in the time period from 0 to t1, the grid-side inverter is in a normal operating state; in the time period from t1 to t2, the grid-side inverter is in a low voltage ride through state, and the grid voltage continuously decreases and then continuously increases. By determining whether the detected grid voltage increases from less than the first voltage threshold to greater than the second voltage threshold, it may be determined whether the low voltage ride through condition is restored. And in the period from t2 to t3, the grid voltage is increased to be larger than a second voltage threshold value, the grid voltage is recovered to a normal region with small fluctuation, and the grid-side inverter is in a low voltage ride through recovery state. At time t2, when the grid voltage is detected to be greater than the second voltage threshold, step S240 is executed. If the grid voltage does not increase to the second voltage threshold, it is determined that the grid-side inverter is still in the low voltage ride through state, and the step S220 is continuously performed.
And S240, controlling the working current limit value of the grid-side inverter to linearly increase along with time, and controlling a brake unit of the wind generating set to release the energy of the direct current bus when detecting that the voltage of the direct current bus is greater than a preset release voltage threshold value.
When the fact that the voltage of the power grid is larger than the second voltage threshold value is detected, the fact that the grid-side inverter is in a low-voltage ride-through recovery state is determined, the working current limit value of the grid-side inverter is controlled to be gradually increased, the power value of the grid-side inverter is limited in a mode that the working current of the grid-side inverter is limited to be increased too fast, and therefore the problem of overvoltage of a direct-current bus is solved. Preferably, the operating current limit of the grid-side inverter is controlled to increase linearly with time. Of course, in other embodiments, the operating current limit of the grid-side inverter may also be controlled to gradually increase according to a non-linear function of time, or other forms such as a stepwise function.
As shown in fig. 3, during the period from 0 to t1 when the grid-side inverter normally works, the working current limit of the grid-side inverter can be controlled to be the maximum working current Imax(ii) a In the time period from t1 to t2 when the grid-side inverter is in a low-voltage ride-through state, the working current limit value of the grid-side inverter can be controlled to be the maximum current limit value I in a mode of upper reactive current priority controlmax1(ii) a During the period t 2-t 3 when the grid-side inverter is in the low voltage ride through recovery state, the following formula can be adopted: i ismax2And controlling the working current limit value of the grid-side inverter to linearly increase along with time. Here, time t is counted from time t2, and K is a slope.
In addition, in practical application, the gradual increase of the working current limit of the grid-side inverter can be realized by respectively controlling the gradual increase of the active current limit and the reactive current limit of the grid-side inverter. For example, the active current limit I is controlled separatelyd_maxAccording to the formula: i isd_max＝KdT increases linearly with time, and controls the reactive current limit Iq_maxAccording to the formula: i isq_max＝KqT at any timeThe interval increases linearly. Wherein time t is measured from time t2, KdAnd KqRespectively, the slope.
Or respectively controlling the active power limit value and the reactive power limit value of the grid-side inverter to gradually increase, so that the active current and the reactive current are limited by respectively limiting the active power and the reactive power under the condition that the voltage is constant or the change is small, and further realizing the purpose of gradually increasing the working current limit value of the grid-side inverter.
In this embodiment, the dc bus voltage is detected in real time, and when it is detected that the dc bus voltage is greater than the preset bleeding voltage threshold, the braking unit is controlled to bleed the dc bus energy. For example, when the grid-side inverter is in a low voltage ride through recovery state, if it is detected that the voltage of the direct current bus is increased to be greater than a preset leakage voltage threshold value, in order to prevent the problem of overvoltage of the direct current bus, the brake unit of the wind generating set is controlled to discharge the energy of the direct current bus. Specifically, the power module in the brake unit can be controlled to be started, the energy of the direct current bus is released through the brake resistor connected with the power module, and the situation that the voltage of the direct current bus exceeds the maximum working voltage due to the fact that the injection quantity of active power injected into the direct current bus by the machine side rectifier is larger than the inversion power quantity of the grid side inverter is avoided, so that the problem of overvoltage of the direct current bus is further prevented.
And S250, judging whether the working current limit value is increased to the maximum working current or not.
As shown in fig. 3, when the operating current limit of the grid-side inverter is gradually increased, if the operating current limit of the grid-side inverter is not increased to the maximum operating current ImaxThen, step S240 is continuously executed, and the operating current limit of the grid-side inverter is controlled to be continuously increased. If the working current limit value of the grid side inverter is increased to the maximum working current ImaxThen, step S260 is executed to set the maximum operating current ImaxThe operating current limit of the grid-side inverter is set.
And S260, setting the maximum working current of the grid-side inverter as the working current limit value of the grid-side inverter, and controlling the grid-side inverter to execute active current priority control.
Passing through the side of the netWhen the low voltage of the inverter passes through the recovery state time period t 2-t 3, the grid voltage recovers to a normal region, the working mode of the grid-side inverter can be switched to a normal working mode, namely, the maximum working current I of the grid-side inverter is switchedmaxSet to the operating current limit. And when the voltage of the power grid is completely recovered to a normal area, the control network side inverter is switched from the execution of reactive current priority control to the execution of active current priority control, so that the success rate of low voltage ride through can be further ensured.
In an optional embodiment, the active current priority control performed by the grid-side inverter is as follows: firstly, obtaining an active current given value I through a direct current bus outer ring controller in a wind generating setd_refAnd judging the given value I of the active currentd_refWhether or not it is greater than the maximum operating current Imax. If Id_refIs greater than ImaxThen I will bed_refIs modified to Imax. If Id_refIs less than or equal to ImaxThen I is not modifiedd_ref. Then, calculating a given reactive current value I by a reactive current controller in the wind generating setq_refAnd judging the given value I of the reactive currentq_refWhether or not to satisfy
If so, not modifying Iq_ref(ii) a If not, then Iq_refIs modified into
Finally, determining Iq_refAnd Id_refAnd the grid-side inverter control algorithm is used for generating a gate switching signal for controlling the IGBT of the grid-side inverter.
The above method for controlling the grid-side inverter of the wind turbine generator system in this embodiment is equivalent to that, in a transition stage between the low voltage ride through state and the normal operating state of the grid-side inverter, the working current limit value of the grid-side inverter is controlled to be gradually increased to control the increasing speed of the working current of the grid-side inverter, so as to limit the power value of the grid-side inverter, achieve the purpose of limiting the energy absorbed by the dc bus, and effectively solve the problem of overvoltage of the dc bus.
In an actual application scenario, the control method of the grid-side inverter may also be adapted to adjust the sequence of each step. For example, in step S260, the operating current limit of the grid-side inverter is increased to the maximum operating current ImaxAnd when the control network side inverter is switched from the reactive current priority control to the active current priority control, the success rate of low voltage ride through is further improved. In practical applications, when the grid voltage increases to be greater than the second voltage threshold of the normal region, the grid-side inverter may be controlled to switch from performing reactive current priority control to performing active current priority control, so as to increase the inversion power of the grid-side inverter.
On the basis of the first embodiment, the specific way of controlling the working current limit value of the grid-side inverter to be gradually increased when the grid-side inverter is in the low-voltage ride-through recovery state is further shown, so that the increase speed of the working current of the grid-side inverter is effectively limited, and the purpose of limiting the power value of the grid-side inverter is achieved, the energy absorbed by the direct-current bus is limited, and the problem of overvoltage of the direct-current bus is effectively solved; and when the working current limit value of the grid-side inverter is increased to the maximum working current, the grid-side inverter is controlled to switch from the reactive current priority control to the active current priority control, so that the success rate of low-voltage ride through is further improved.
EXAMPLE III
Fig. 4 is a block diagram showing a configuration of an inverter control device of a wind turbine generator system according to a third embodiment of the present invention.
As shown in fig. 4, the inverter control apparatus of the wind turbine generator set includes a detection module 410 and a first control module 420. The detection module 410 is configured to determine that a grid-side inverter of the wind turbine generator system enters a low voltage ride through state if it is detected that the grid voltage is less than a first voltage threshold; the first control module 420 is configured to control the operating current limit of the grid-side inverter to gradually increase if the grid-side inverter is already in a low voltage ride through state and detects that the grid voltage increases above a second voltage threshold, wherein the second voltage threshold is greater than the first voltage threshold.
According to the inverter control device of the wind generating set, whether the grid-side inverter of the wind generating set enters the low voltage ride through state is determined by detecting whether the grid voltage is too small, the grid voltage is continuously detected in the low voltage ride through state, and when the grid voltage is increased to the normal state, the working current limit value of the grid-side inverter is controlled to be gradually increased so as to achieve the purpose of limiting the power value of the grid-side inverter, so that the problem of overvoltage of a direct current bus caused by the fact that the grid-side inverter absorbs the power of a power grid from the power grid is solved, the problem of device failure is further avoided, and the maintenance cost of the wind generating set is reduced.
Further, the first control module 420 is further configured to set the maximum operating current as the operating current limit of the grid-side inverter when the operating current limit of the grid-side inverter is increased to the maximum operating current of the grid-side inverter.
Further, the inverter control device of the present embodiment further includes a second control module 430, configured to control the grid-side inverter to switch from performing active current priority control to performing reactive current priority control if it is detected that the grid voltage is less than the first voltage threshold.
Further, the inverter control apparatus of the present embodiment further includes a third control module 440, configured to control the grid-side inverter to switch from performing reactive current priority control to performing active current priority control when it is detected that the grid voltage increases to be greater than the second voltage threshold; or, the controller is configured to control the grid-side inverter to switch from performing reactive current priority control to performing active current priority control when the operating current limit of the grid-side inverter is increased to the maximum operating current of the grid-side inverter.
Further, the first control module 420 is configured to control the operating current limit of the grid-side inverter to increase linearly with time.
Further, the first control module 420 is configured to control the active current limit and the reactive current limit of the grid-side inverter to gradually increase; and/or gradually increasing the active power limit value and the reactive power limit value of the control network side inverter.
Further, the inverter control apparatus of this embodiment further includes a fourth control module 450, configured to control a braking unit of the wind generating set to discharge the energy of the dc bus when it is detected that the dc bus voltage is greater than the preset discharge voltage threshold.
In practical applications, the inverter control device of the present embodiment may be integrated in a converter controller of a wind turbine generator system, may also be integrated in a grid-side inverter control, and may of course be provided independently of the converter controller and the grid-side inverter controller.
The inverter control device of this embodiment may be configured to execute the inverter control method of the wind turbine generator system according to the first embodiment or the second embodiment, so as to control the working current limit value of the grid-side inverter to gradually increase when the grid-side inverter is in the low voltage ride through recovery state, further limit the increasing speed of the working current of the grid-side inverter, and achieve the purpose of limiting the power value of the grid-side inverter, thereby limiting the energy absorbed by the dc bus and effectively solving the problem of overvoltage of the dc bus.
It should be noted that, according to the implementation requirement, each component/step described in the present application can be divided into more components/steps, and two or more components/steps or partial operations of the components/steps can be combined into a new component/step to achieve the purpose of the present invention.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (8)
1. An inverter control method of a wind turbine generator system, comprising:
if the detected grid voltage is smaller than the first voltage threshold value, determining that a grid-side inverter of the wind generating set enters a low-voltage ride-through state;
controlling the operational current limit of the grid-side inverter to gradually increase if the grid-side inverter is already in the low voltage ride-through state and an increase in grid voltage above a second voltage threshold is detected, wherein the second voltage threshold is greater than the first voltage threshold,
wherein gradually increasing the operating current limit of the grid-side inverter comprises: the active current limit value and the reactive current limit value of the control network side inverter are gradually increased;
setting the maximum operating current to an operating current limit of the grid-side inverter when the operating current limit of the grid-side inverter is increased to the maximum operating current of the grid-side inverter,
wherein, the gradual increase of the working current limit of the control network side inverter further comprises: the active power limit and the reactive power limit of the control grid side inverter are gradually increased,
wherein, the working current limit value of control net side inverter increases gradually, includes:
the operating current limit of the control grid side inverter increases linearly with time.
2. The inverter control method of claim 1, further comprising, after the if the detected grid voltage is less than the first voltage threshold:
and controlling the grid-side inverter to switch from performing active current priority control to performing reactive current priority control.
3. The inverter control method according to claim 2, further comprising:
when the grid voltage is detected to be increased to be larger than a second voltage threshold value, controlling the grid-side inverter to switch from performing reactive current priority control to performing active current priority control; or,
and when the working current limit value of the grid-side inverter is increased to the maximum working current of the grid-side inverter, controlling the grid-side inverter to switch from the execution of reactive current priority control to the execution of active current priority control.
4. The inverter control method according to claim 3, characterized by further comprising:
and when detecting that the voltage of the direct current bus is greater than a preset discharge voltage threshold value, controlling a brake unit of the wind generating set to discharge the energy of the direct current bus.
5. An inverter control device for a wind turbine generator system, comprising:
the detection module is used for determining that a grid-side inverter of the wind generating set enters a low voltage ride through state if the grid voltage is detected to be smaller than a first voltage threshold;
a first control module, configured to control an operating current limit of the grid-side inverter to gradually increase if the grid-side inverter is already in the low-voltage ride-through state and it is detected that a grid voltage increases to be greater than a second voltage threshold, where the second voltage threshold is greater than the first voltage threshold, and the first control module controls an active current limit and a reactive current limit of the grid-side inverter to gradually increase;
the first control module is further configured to:
setting the maximum operating current to an operating current limit of the grid-side inverter when the operating current limit of the grid-side inverter is increased to the maximum operating current of the grid-side inverter,
wherein the first control module also controls the active power limit value and the reactive power limit value of the grid-side inverter to gradually increase,
wherein the first control module is configured to: the operating current limit of the control grid side inverter increases linearly with time.
6. The inverter control device according to claim 5, characterized by further comprising:
and the second control module is used for controlling the grid-side inverter to switch from performing active current priority control to performing reactive current priority control if the grid voltage is detected to be smaller than the first voltage threshold.
7. The inverter control device according to claim 5, characterized by further comprising:
the third control module is used for controlling the grid-side inverter to switch from the reactive current priority control to the active current priority control when the grid voltage is detected to be increased to be larger than the second voltage threshold; or, the controller is configured to control the grid-side inverter to switch from performing reactive current priority control to performing active current priority control when the operating current limit of the grid-side inverter is increased to the maximum operating current of the grid-side inverter.
8. The inverter control device according to claim 6, further comprising:
and the fourth control module is used for controlling the brake unit of the wind generating set to release the energy of the direct current bus when detecting that the voltage of the direct current bus is greater than a preset release voltage threshold value.
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| WO2019101306A1 (en) * | 2017-11-22 | 2019-05-31 | Siemens Aktiengesellschaft | Energy transmission via a bipolar high voltage direct current transmission link |
| CN108539751B (en) * | 2018-05-09 | 2020-04-10 | 国网湖南省电力有限公司 | Regional power grid AVC control method and system |
| CN109755966B (en) * | 2019-03-25 | 2020-08-04 | 哈尔滨工业大学 | Cooperative fault ride-through method for large-scale offshore wind power through flexible direct current delivery |
| CN117578536B (en) * | 2023-10-19 | 2024-06-18 | 上海勘测设计研究院有限公司 | Network-structured energy storage control method and system for weak alternating current system |
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