CN115313432B

CN115313432B - Control method, device, medium, controller and wind generating set

Info

Publication number: CN115313432B
Application number: CN202211194971.5A
Authority: CN
Inventors: 于笑; 高保峰; 郭锐
Original assignee: Beijing Goldwind Science and Creation Windpower Equipment Co Ltd
Current assignee: Beijing Goldwind Science and Creation Windpower Equipment Co Ltd
Priority date: 2022-09-29
Filing date: 2022-09-29
Publication date: 2023-01-20
Anticipated expiration: 2042-09-29
Also published as: WO2024066712A1; CN115313432A

Abstract

The disclosure provides a control method, a control device, a control medium, a controller and a wind generating set. The control method of the voltage source type wind generating set comprises the following steps: obtaining the phase of grid-connected point voltage and grid-connected point current of a wind generating set; determining the phase of the virtual internal potential of the wind generating set according to the phase of the grid voltage of the grid-connected point; obtaining the amplitude of the virtual internal potential of the wind generating set; generating a first modulation signal based on the magnitude and phase of the virtual internal potential; in response to the grid-connected point current being greater than a first preset threshold, superimposing a voltage deviation corresponding to the virtual impedance on the first modulation signal to obtain a second modulation signal; generating a first drive signal based on the second modulation signal; and controlling the operation of a grid-side converter of the wind generating set by using the first driving signal during the short circuit of the power grid.

Description

Control method, device, medium, controller and wind generating set

Technical Field

The present disclosure relates generally to the field of wind power generation technology, and more particularly, to a method, an apparatus, a medium, a controller, and a wind power generator set for controlling a voltage source type wind power generator set.

Background

Generally, a grid-connected type or current source control strategy is adopted by a wind power converter, for example, a patent document with publication number CN110572057A discloses a specific harmonic suppression method for a current source converter at an extremely low switching frequency.

However, as the permeability of new energy power generation in the power system is gradually improved, the power system presents the characteristics of weakened power grid strength, reduced inertia level and the like, the risk of system safety and stability is increased, and the construction and development of a novel power system are restricted. In order to improve the supporting effect of the wind power generation technology on the power system, the development and application of the grid-structured (voltage source-type) wind generating set are receiving wide attention.

The grid-connected wind generating set still carries out energy conversion and grid-connected control based on power electronic equipment, and because the overcurrent capacity of the current power electronic device is poor, a current-limiting control strategy needs to be applied under the condition of a power grid short-circuit fault so as to prevent the trigger unit overcurrent protection from triggering to cause shutdown and grid disconnection.

The current limiting strategy of the networking type control technology is a virtual impedance control algorithm, namely after a short-circuit fault is detected, virtual impedance is equivalently connected in series between the potential in the networking and a grid-connected point, and grid-connected short-circuit current is ensured to be within the allowable range of the safe operation capacity of equipment.

Although the virtual impedance control strategy can ensure safe and reliable operation of the grid-connected equipment during a short-circuit fault, the low short-circuit current capacity of the equipment limits the supporting capacity of the grid-connected equipment to a power grid, and particularly, a large amount of short-circuit reactive current support cannot be provided for the power grid during the short-circuit fault, so that the voltage fluctuation range of a system node is large, and the voltage stability and the recovery after the fault of a power system are not facilitated.

The above information may include technical content that is not prior art.

Disclosure of Invention

The embodiment of the disclosure provides a control method and a control device of a voltage source type wind generating set, which can improve the supporting capability of the voltage source type wind generating set on the voltage stability of a power grid.

According to an aspect of the present disclosure, a control method of a voltage source type wind turbine generator system includes: obtaining the phase of grid-connected point voltage and grid-connected point current of a wind generating set; determining the phase of the virtual internal potential of the wind generating set according to the phase of the grid voltage of the grid-connected point; obtaining the amplitude of the virtual internal potential of the wind generating set; generating a first modulation signal based on the magnitude and phase of the virtual internal potential; in response to the grid-connected point current being larger than a first preset threshold, superposing a voltage deviation corresponding to the virtual impedance on the first modulation signal to obtain a second modulation signal; generating a first drive signal based on the second modulation signal; and controlling the operation of a grid-side converter of the wind generating set by using the first driving signal during the short circuit of the power grid.

Optionally, the control method may further include: and in response to the grid-connected point current being larger than a first preset threshold and the grid-connected point voltage being lower than a second preset threshold, maintaining the phase and amplitude of the virtual internal potential as the phase and amplitude before the grid short circuit during the grid short circuit.

Optionally, the control method may further include: and in response to the condition that the current of the grid-connected point is larger than a first preset threshold and the voltage of the grid-connected point is lower than a second preset threshold, controlling a machine side converter of the wind generating set to operate during the short circuit of the grid so as to keep the voltage of a direct-current bus of the wind generating set stable.

Optionally, the control method may further include: and in response to the grid-connected point current being larger than a first preset threshold and the grid-connected point power grid voltage being lower than a second preset threshold, reducing the starting voltage of a brake unit of a converter of the wind generating set.

Optionally, the control method may further include: and reducing the frequency of the first driving signal in response to the grid-connected point current being greater than a first preset threshold and the grid-connected point power grid voltage being lower than a second preset threshold.

Optionally, the step of determining the phase of the virtual internal potential of the wind turbine generator set according to the phase of the grid-connected point grid voltage may include: and determining the phase of the virtual internal potential of the wind generating set according to the phase of the virtual internal potential of the wind generating set, the torque/power command value received from the main controller and the active power measured value of the wind generating set.

Optionally, the step of determining the phase of the virtual internal potential of the wind park, based on the phase of the virtual internal potential of the wind park, the torque/power command value received from the main controller and the active power measurement of the wind park, may comprise: and performing PI regulation on the difference between the torque/power instruction value and the active power measured value of the wind generating set to obtain an angular frequency, and calculating the angular frequency by taking the phase of the grid voltage of the grid-connected point as an integral value of an initial value so as to determine the phase of the virtual internal potential of the wind generating set.

Optionally, the step of obtaining the magnitude of the virtual internal potential of the wind park may comprise: and performing PI regulation on the difference between the reactive/voltage command value received from the main controller and the voltage feedback value of the converter of the wind generating set to obtain the amplitude of the virtual internal potential.

According to a second aspect of the present disclosure, a control device of a voltage source type wind turbine generator set includes: the grid voltage phase detection unit is used for obtaining the phase of grid voltage of a grid-connected point of the wind generating set; the synchronization unit is used for determining the phase of the virtual internal potential of the wind generating set according to the phase of the grid voltage of the grid-connected point; the internal potential amplitude determining unit is used for obtaining the amplitude of the virtual internal potential of the wind generating set; a modulation unit that generates a first modulation signal based on the amplitude and phase of the virtual internal potential and superimposes a voltage deviation corresponding to a virtual impedance to the first modulation signal in response to the grid-connected point current being greater than a first preset threshold to obtain a second modulation signal and generates a first drive signal based on the second modulation signal; and the grid-side converter control unit controls the operation of the grid-side converter of the wind generating set during the short circuit of the power grid by using the first driving signal.

Optionally, the control device may further include: and the machine side converter controller is configured to respond to the grid-connected point current being larger than a first preset threshold and the grid-connected point voltage being lower than a second preset threshold, and control the machine side converter of the wind generating set to operate during the grid short circuit period so as to keep the direct current bus voltage of the wind generating set stable.

Optionally, the modulation unit may be configured to: and in response to the grid-connected point current being larger than a first preset threshold and the grid-connected point voltage being lower than a second preset threshold, maintaining the phase and amplitude of the virtual internal potential as the phase and amplitude before the grid short circuit during the grid short circuit.

Optionally, the control device may further include: the brake control unit is configured to respond to the grid-connected point current being larger than a first preset threshold and the grid-connected point power grid voltage being lower than a second preset threshold, and the starting voltage of the brake unit of the converter of the wind generating set is reduced.

Optionally, the modulation unit may be configured to: and reducing the frequency of the first driving signal in response to the grid-connected point current being greater than a first preset threshold and the grid-connected point power grid voltage being lower than a second preset threshold.

According to a third aspect of the present disclosure, there is provided a computer-readable storage medium storing a computer program which, when executed by a processor, implements the above-described control method.

According to a fourth aspect of the present disclosure, there is provided a controller comprising: a processor; and a memory storing a computer program for realizing the control method of the voltage source type wind turbine generator system when the computer program is executed by the processor.

According to a fifth aspect of the present disclosure, there is provided a wind turbine generator system including the control device of the voltage source type wind turbine generator system described above.

According to the control method and the control device of the voltage source type wind generating set disclosed by the embodiment of the disclosure, under the safety constraint of maintaining the heat balance of the power semiconductor and turning off the overvoltage, the short-circuit current level can be increased to be more than 1.5pu (rated current) during the short-circuit fault period.

Drawings

The above and other objects and features of the embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings illustrating the embodiments, in which:

fig. 1 is a block diagram showing a control system of a voltage source type wind turbine generator set;

fig. 2 is a flowchart illustrating a control method of a voltage source type wind turbine generator set according to an embodiment of the present disclosure;

fig. 3 is a flowchart illustrating a control method of a voltage source type wind turbine generator set according to an embodiment of the present disclosure;

fig. 4 is a flowchart illustrating a control method of a voltage source type wind turbine generator set according to an embodiment of the present disclosure;

fig. 5 is a flowchart illustrating a control method of a voltage source type wind turbine generator set according to an embodiment of the present disclosure;

fig. 6 is a flowchart illustrating a control method of a voltage source type wind turbine generator set according to an embodiment of the present disclosure;

fig. 7 is a flowchart illustrating a control method of a voltage source type wind turbine generator set according to an embodiment of the present disclosure;

fig. 8 is a block diagram showing a control apparatus of a voltage source type wind turbine generator set according to an embodiment of the present disclosure;

fig. 9 is a block diagram illustrating a control apparatus of a voltage source type wind turbine generator set according to an embodiment of the present disclosure.

Detailed Description

The following detailed description is provided to assist the reader in obtaining a thorough understanding of the methods, devices, and/or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and/or systems described herein will be apparent to those skilled in the art after reviewing the disclosure of the present application. For example, the order of operations described herein is merely an example, and is not limited to those set forth herein, but may be changed as will become apparent after understanding the disclosure of the present application, except to the extent that operations must occur in a particular order. Moreover, descriptions of features known in the art may be omitted for greater clarity and conciseness.

The features described herein may be embodied in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein have been provided to illustrate only some of the many possible ways to implement the methods, apparatus and/or systems described herein, which will be apparent after understanding the disclosure of the present application.

As used herein, the term "and/or" includes any one of the associated listed items and any combination of any two or more.

Although terms such as "first," "second," and "third" may be used herein to describe various elements, components, regions, layers or sections, these elements, components, regions, layers or sections should not be limited by these terms. Rather, these terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section referred to in the examples described herein could also be referred to as a second element, component, region, layer or section without departing from the teachings of the examples.

The terminology used herein is for the purpose of describing various examples only and is not intended to be limiting of the disclosure. The singular is also intended to include the plural unless the context clearly indicates otherwise. The terms "comprises," "comprising," and "having" specify the presence of stated features, quantities, operations, elements, components, and/or combinations thereof, but do not preclude the presence or addition of one or more other features, quantities, operations, components, elements, and/or combinations thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs after understanding the present disclosure. Unless explicitly defined as such herein, terms (such as those defined in general dictionaries) should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and should not be interpreted in an idealized or overly formal sense.

Further, in the description of the examples, when it is considered that detailed description of well-known related structures or functions will cause a vague explanation of the present disclosure, such detailed description will be omitted.

The control method of the voltage source type wind generating set according to the embodiment of the disclosure can be applied to the situation that the short circuit occurs in the power system. Through virtual impedance control and switching frequency reduction control, the starting threshold value of the brake unit is reduced, the direct-current bus voltage is maintained, and the like, and the short-circuit current level of the voltage source type wind generating set can be remarkably improved to be more than 1.5 pu. Specific implementations according to embodiments of the present disclosure are described in detail below with reference to fig. 1 to 9.

Fig. 1 is a block diagram showing a control system of a voltage source type wind turbine generator system.

A control system of a voltage source wind park according to embodiments of the present disclosure may comprise a main controller 160, a pitch controller 170, a machine side converter controller 180 and a grid side converter controller 150.

The machine-side converter controller 180 is mainly used for controlling the voltage of a direct-current bus to be constant, measuring and calculating the electromagnetic torque of the generator 110, feeding back the electromagnetic torque to the main controller 160, and controlling a switching tube of the machine-side converter 120, the main controller 160 issues a pitch angle instruction to the pitch controller 170 to adjust the mechanical torque input by the impeller, and issues a torque or power instruction to the grid-side converter controller 150 to indirectly control the electromagnetic torque of the generator, and the grid-side converter controller 150 can be used for controlling the grid-side converter 130, and can execute a core algorithm of grid-type control and a virtual impedance control technology.

Although not shown, the control system of the voltage source type wind turbine generator set according to the embodiment of the present disclosure may further include a controller for controlling a brake unit, which refers to a brake module that discharges a high voltage on the dc bus when, for example, a high voltage ride through occurs. The internal potential or virtual internal potential according to an embodiment of the present disclosure refers to a potential at a node (e.g., node E) between the output terminal of the grid-side current transformer 130 and the LC filter 140. Furthermore, the control method described below may be performed by a master controller, a grid-side converter controller and/or a machine-side converter controller, etc.

Fig. 2 to 7 are flowcharts illustrating a control method of a voltage source type wind turbine generator set according to an embodiment of the present disclosure.

As shown in fig. 2, the control method of the voltage source type wind generating set according to the embodiment of the present disclosure may include step S110, step S120, step S130, step S140, step S150, step S160, and step S170.

In step S110, a phase of a grid-connected point grid voltage V1 of the wind turbine generator system and a grid-connected point current I1 may be obtained. The grid-connected point grid voltage is the grid voltage at the grid-connected point of the whole wind generating set.

As an example, the grid-connected point grid voltage and the grid-connected point current may be obtained by respective sensors, and the phase of the grid-connected point grid voltage may be obtained by performing phase locking using a phase-locked loop (PLL). The control method according to the embodiment of the present disclosure may obtain the phase of the grid-connected point power grid voltage by performing PLL once before performing the grid-configuration-type control algorithm, unlike the prior art, without performing PLL all the time during the execution of the algorithm.

In step S120, a phase of the virtual internal potential of the wind turbine generator set may be determined according to the phase of the grid-connected point grid voltage.

As an example, the step of determining the phase of the virtual internal potential of the wind park from the phase of the grid-connected point voltage may comprise: and determining the phase of the virtual internal potential of the wind generating set according to the phase of the virtual internal potential of the wind generating set, the torque/power command value received from the main controller and the active power measured value of the wind generating set.

Optionally, the step of determining the phase of the virtual internal potential of the wind park from the phase of the virtual internal potential of the wind park, the torque/power command value received from the main controller and the active power measurement value of the wind park may comprise: and performing PI regulation on the difference between the torque/power instruction value received from the main controller and the active power measured value of the wind generating set to obtain an angular frequency, and calculating the angular frequency to take the phase of the grid-connected point power grid voltage as an integral value of an initial value so as to determine the phase of the virtual internal potential of the wind generating set.

For example, PI regulation may be performed on a difference between a torque power command value and an active power measurement value (i.e., output active power measured at a grid-connected point or an outlet of the entire wind turbine generator system) to obtain an angular frequency, and then the angular frequency may be calculated with a phase of a grid-connected point grid voltage as an integral value of an initial value to determine a phase of a virtual internal potential of the wind turbine generator system. The torque power instruction value can be converted into a power instruction value (power is the product of torque and rotating speed), then PI regulation is carried out on the difference between the converted power instruction value and an active power measured value, so that angular frequency is obtained, then the angular frequency is calculated, and the phase of grid-connected point power grid voltage is used as an integral value of an initial value, so that the phase of virtual internal potential of the wind generating set is determined.

The phase of the virtual internal potential can also be obtained through an inertia element, for example, the phase of the grid-connected point power grid voltage can be obtained through first-order and/or second-order low-pass filtering, and the phase of the grid-connected point power grid voltage can also be obtained through the combination of the inertia element and a PI controller (or PI algorithm).

Alternatively, when the phase of the internal potential is obtained based on PI adjustment, an appropriate response speed can be obtained by adjusting the proportional coefficient and the integral coefficient of the PI element. When the phase of the internal potential is obtained by low-pass filtering, an appropriate response speed can be obtained by adjustment of a filter parameter (for example, cutoff frequency).

In step S130, the magnitude of the virtual internal potential of the wind turbine generator set is obtained.

As an example, the difference between the reactive/voltage command value received from the main controller and the voltage feedback value of the converter of the wind park may be PI-regulated to obtain the magnitude of the virtual internal potential.

Specifically, PI regulation may be performed on a difference between a reactive/voltage command value received from the main controller and a voltage feedback value of a converter of the wind turbine generator set to obtain an amplitude of the virtual internal potential.

In step S140, a first modulation signal is generated based on the amplitude and phase of the virtual internal potential.

The first modulation signal may be a sine wave signal, and the first modulation signal may be directly obtained according to the amplitude and phase of the obtained virtual internal potential.

A magnitude relationship between the dot-on point current I1 and the first preset threshold Th1 may be determined in step S1501.

In step S150, in response to the dot-on point current I1 being greater than the first preset threshold Th1, a voltage deviation corresponding to the virtual impedance is superimposed to the first modulation signal to obtain a second modulation signal.

The virtual impedance may be predetermined, for example, a voltage deviation may be obtained by multiplying the fed back grid-connected point current by the predetermined virtual impedance, and the voltage deviation may be superimposed on the first modulation signal to obtain the second modulation signal. The virtual impedance control scheme herein may reduce the output current of the grid-side converter.

In step S160, a first driving signal is generated based on the second modulation signal. For example, the second modulation signal may be loaded to a Pulse Width Modulation (PWM) unit, which generates the first drive signal based on the second modulation signal.

In step S170, during the grid short circuit, the grid-side converter of the wind turbine generator system is controlled to operate by using the first driving signal.

Whether the power grid is short-circuited can be judged through the magnitude relation between the grid-connected point current I1 and a first preset threshold Th 1.

According to an embodiment of the present disclosure, the grid control may be performed based on the magnitude and phase of the internal potential and the virtual impedance control.

Referring to fig. 3, the control method according to an embodiment of the present disclosure further includes: and in response to the grid-connected point current being larger than a first preset threshold and the grid-connected point voltage being lower than a second preset threshold, maintaining the phase and amplitude of the virtual internal potential as the phase and amplitude before the grid short circuit during the grid short circuit.

In the control process of the grid-connected wind generating set, the amplitude and the phase of the internal potential can be locked, so that the amplitude and the phase are kept at a steady state value before a fault, the virtual impedance control is enabled, and the amplitude of the grid-connected short circuit current is limited within a certain range and can be at least greater than 1.5pu (rated current).

The magnitude relationship between the grid-connected point grid voltage V1 and the second preset threshold Th2 may be determined in step S1502. Step S1501 and step S1502 may be part of the control method of the present disclosure.

Referring to fig. 4, the control method according to an embodiment of the present disclosure may further include step S180.

In step S180, in response to that the current of the grid-connected point I1 is greater than a first preset threshold Th1 and the grid voltage V1 of the grid-connected point is lower than a second preset threshold Th2, during a short circuit of the grid, controlling a machine-side converter of the wind generating set to operate so as to keep the dc bus voltage of the wind generating set stable.

Specifically, referring to fig. 7, the step S180 of controlling the dc bus voltage to be stable may include step S1801, step S1802, step S1803, step S1804, and step S1805.

In step S1801, a vector phase of a generator-side voltage of a generator of the wind turbine generator system may be obtained.

As an example, the generator side voltage may be determined by detecting the three phase currents on the generator side and the resistive impedance on the generator side, and then the vector phase of the generator side voltage may be determined based on the generator side voltage.

In step S1802, a q-axis current value may be obtained based on the dc bus voltage.

As an example, obtaining the q-axis current value based on the dc bus voltage may include: the q-axis current value may be obtained by performing PI regulation on the dc bus voltage, and the reference value or the given value of the dc bus voltage may be set in advance.

In step S1803, a d-axis current value may be obtained based on the terminal voltage.

As an example, the step of obtaining the d-axis current value based on the terminal voltage may include: PI regulation is performed on the difference between the reference value of the terminal voltage and the reference value of the terminal voltage to obtain a d-axis current value.

In step S1804, a modulation signal is determined according to the vector phase, the q-axis current value, and the d-axis current value and a second drive signal is generated based on the modulation signal.

As an example, the step of determining the modulation signal from the vector phase, the q-axis current value, and the d-axis current value may include: PI adjustment is performed using the vector phase, the q-axis current value, and the d-axis current value to obtain a modulation signal.

Specifically, PI adjustment may be performed on the difference between the q-axis current value and the q-axis current reference value to obtain an angular frequency, and then integration with the vector phase as an initial value to obtain a phase. PI regulation can be carried out on the difference between the d-axis current value and the d-axis current reference value to obtain the amplitude, and the modulation signal can be directly obtained according to the obtained amplitude and phase. As an example, PI adjustment may also be performed on the difference between the d-axis current value and the d-axis current reference value to obtain the amplitude, and PI adjustment may be performed on the difference between the q-axis current value and the q-axis current reference value to obtain the phase.

In step S1805, the second driving signal is used to control the operation of the machine-side converter of the wind turbine generator system, so as to keep the dc bus voltage of the wind turbine generator system stable.

The above-described dc bus voltage stabilization control method is merely an example, and the dc bus voltage stabilization may be controlled in other manners.

When the voltage of the direct current bus is abnormally increased, the opening action of the braking unit is controlled to dissipate the overflow power of the direct current side.

Referring to fig. 5, the control method according to an embodiment of the present disclosure may further include step S190.

In step S190, in response to the current of the grid-connected point I1 being greater than the first preset threshold Th1 and the grid-connected point voltage V1 being lower than the second preset threshold Th2, during the grid short circuit, the starting voltage of the braking unit of the converter of the wind turbine generator system is reduced.

Referring to fig. 6, the control method according to an embodiment of the present disclosure may further include step S200.

In step S200, in response to that the current of the grid-connected point I1 is greater than a first preset threshold Th1 and the grid voltage V1 of the grid-connected point is lower than a second preset threshold Th2, the frequency of the first driving signal is reduced. For example, the frequency of the carrier signal may be changed to change the frequency of the first drive signal.

Similarly, the magnitude relationship between the grid-connected point grid voltage V1 and the second preset threshold Th2 may be determined in step S1502. Step S1501 and step S1502 may be part of the control method of the present disclosure.

It should be noted that at least two of the step of maintaining the phase and the amplitude before the grid short circuit, the step S180, the step S190, and the step S200 may be executed in parallel or sequentially, and the execution sequence is not particularly limited.

The description of the same steps as fig. 2 in fig. 3 to 6 is omitted here.

Fig. 8 and 9 are block diagrams illustrating a control apparatus of a voltage source type wind turbine generator set according to an embodiment of the present disclosure.

As shown in fig. 8, the control apparatus 500 of the voltage source type wind generating set according to the embodiment of the present disclosure may include a grid voltage phase detecting unit 510, a synchronizing unit 520, an internal potential amplitude determining unit 530, a modulating unit 540, and a grid-side converter control unit 550.

The grid voltage phase detection unit 510 may obtain a phase of a grid voltage of a grid-connected point of the wind turbine. The grid voltage phase detection unit may be configured to detect the phase of the grid voltage before the converter is started.

The synchronization unit 520 may determine the phase of the virtual internal potential of the wind turbine generator set according to the phase of the grid-connected point grid voltage.

The synchronization unit 520 may be implemented by an inertia element, for example, the synchronization unit 520 may obtain the phase of the virtual internal potential of the wind turbine generator system by first-order and/or second-order low-pass filtering, or obtain the phase of the virtual internal potential of the wind turbine generator system by a combination of the inertia element and the PI. The synchronization unit 520 may determine the phase of the virtual internal potential of the wind park from the phase of the virtual internal potential of the wind park, the torque/power command value received from the main controller and the active power measurement value of the wind park.

The internal potential magnitude determination unit 530 may obtain a magnitude of the virtual internal potential of the wind park.

The internal potential magnitude determining unit 530 may PI-adjust a difference between a reactive/voltage command value received from the main controller and a voltage feedback value of a converter of the wind turbine generator set to obtain a magnitude of the virtual internal potential.

The internal potential amplitude determination unit 530 may perform PI adjustment on a difference between the torque power command value and an active power measurement value (i.e., output active power measured at a grid-connected point or an outlet of the entire wind turbine generator system) to obtain an angular frequency, and then calculate the angular frequency with the phase of the grid-connected point grid voltage as an integral value of an initial value to determine the phase of the virtual internal potential of the wind turbine generator system. The internal potential amplitude determination unit 530 may also convert the torque power command value into a power command value (power is a product of torque and rotation speed), then perform PI adjustment on a difference between the converted power command value and an active power measurement value, thereby obtaining an angular frequency, and then calculate the angular frequency to use the phase of the grid-connected point grid voltage as an integral value of an initial value, thereby determining the phase of the virtual internal potential of the wind turbine generator system.

The modulation unit 540 may generate a first modulation signal based on the magnitude and phase of the virtual inner potential and superimpose a voltage deviation corresponding to the virtual impedance to the first modulation signal in response to the grid-connected point current being greater than a first preset threshold to obtain a second modulation signal and generate the first driving signal based on the second modulation signal.

The grid-side converter control unit 550 may control the operation of the grid-side converter of the wind park during a grid short-circuit using the first drive signal.

As an example, whether the grid-connected point grid voltage is shorted or not may be determined by the grid-side converter control unit 550, and the grid-side converter control unit 550 may be a part of the grid-side converter controller, a part of the machine-side converter controller, or a part of the main controller. For example, when the grid-connected point current exceeds a predetermined threshold, it may be determined that a grid short circuit has occurred.

The control device 500 of the voltage source type wind generating set according to the embodiment of the present disclosure may further include a machine side converter controller, and the machine side converter controller may control the machine side converter of the wind generating set to operate during the grid short circuit period in response to the grid-connected point current being greater than the first preset threshold and the grid-connected point grid voltage being lower than the second preset threshold, so as to keep the dc bus voltage of the wind generating set stable.

The machine side converter controller may be configured to: obtaining a vector phase of a generator terminal voltage of a generator of the wind generating set; obtaining a q-axis current value based on the direct current bus voltage; obtaining a d-axis current value based on the generator-side voltage; determining a modulation signal according to the vector phase, the q-axis current value and the d-axis current value and generating a second driving signal based on the modulation signal; and controlling the machine side converter of the wind generating set to operate under the grid-connected point power grid voltage disturbance by using the second driving signal so as to keep the direct-current bus voltage of the wind generating set stable.

As an example, the machine side variable flow controller may be further configured to: PI adjustment is performed using the vector phase, the q-axis current value, and the d-axis current value to obtain a modulation signal. The machine-side variable current controller may obtain the q-axis current value by performing PI adjustment on the dc bus voltage, and the machine-side variable current controller may be further configured to obtain the d-axis current value by performing PI adjustment on a difference between the reference value of the machine-side voltage and the machine-side voltage.

Specifically, the machine-side variable current controller may perform PI adjustment on the difference between the q-axis current value and the q-axis current reference value to obtain an angular frequency, and then calculate an integral value of the angular frequency with the vector phase as an initial value to obtain a phase. The machine side current transformation controller can perform PI regulation on the difference between the d-axis current value and the d-axis current reference value to obtain the amplitude, and can directly obtain a modulation signal according to the obtained amplitude and phase. As an example, the machine side variable current controller may also perform PI adjustment on the difference between the d-axis current value and the d-axis current reference value to obtain the amplitude, and perform PI adjustment on the difference between the q-axis current value and the q-axis current reference value to obtain the phase.

The modulation unit 540 may be configured to: and in response to the grid-connected point current being larger than a first preset threshold and the grid-connected point voltage being lower than a second preset threshold, maintaining the phase and amplitude of the virtual internal potential as the phase and amplitude before the grid short circuit during the grid short circuit.

The control apparatus according to an embodiment of the present disclosure may further include a brake control unit, and the brake control unit may be configured to reduce a turn-on voltage of a brake unit of a converter of the wind turbine generator set in response to the grid-connected point current being greater than a first preset threshold and the grid-connected point grid voltage being lower than a second preset threshold.

The modulation unit 540 may be configured to decrease the frequency of the first driving signal in response to the grid-connected point current being greater than a first preset threshold and the grid-connected point grid voltage being lower than a second preset threshold. As described above, the modulation unit may change the frequency of the first driving signal using the carrier signal. For example, the switching frequency of the modulation link (i.e., the switching frequency of the PWM driving signal) may be reduced to below 1.7kHz, thereby reducing the excessive rise of the junction temperature due to the switching loss of the power semiconductor and maintaining the thermal balance of the power module.

The control method according to the embodiment of the present disclosure may be written as a computer program and stored on a computer-readable storage medium. The control method of the voltage source type wind turbine generator set as described above may be implemented when the computer program is executed by the processor.

Examples of computer-readable storage media include: read-only memory (ROM), random-access programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), random-access memory (RAM), dynamic random-access memory (DRAM), static random-access memory (SRAM), flash memory, non-volatile memory, CD-ROM, CD-R, CD + R, CD-RW, CD + RW, DVD-ROM, DVD + R, DVD-RW, DVD + RW, BD-ROM, BD-R LTH, BD-RE, blu-ray or optical disk storage, hard Disk Drive (HDD), solid State Disk (SSD), card storage (such as a multimedia card, secure Digital (SD) card, or extreme digital (XD) card), a tape, a floppy disk, an optical data storage device, a hard disk, a solid state disk, and any other device configured to store and provide computer programs and any associated data, data files and data structures in a non-transitory manner to a processor or a computer such that the computer programs and any associated data, data files and data structures are provided to the computer processor or computer such that the computer can execute the computer programs or the computer programs.

In one example, the computer program and any associated data, data files, and data structures are distributed over a network of networked computer systems such that the computer program and any associated data, data files, and data structures are stored, accessed, and executed in a distributed fashion by one or more processors or computers.

As shown in fig. 9, the controller 600 (e.g., a machine-side converter controller, a grid-side converter controller and/or a main controller) may comprise a processor 610 and a memory 620, the memory storing a computer program which, when executed by the processor, implements the control method of the voltage source wind turbine generator set as described above.

The control device of the voltage source type wind turbine generator set as described above may be a part of a wind turbine generator set (for example, a voltage source type wind turbine generator set).

According to the control method and the control device disclosed by the embodiment of the disclosure, the supporting capability of the voltage source type wind driven generator set on the voltage stability of the power grid can be improved.

According to the control method and the control device of the voltage source type wind generating set, the short-circuit current level can be increased to be more than 1.5pu (rated current) during the short-circuit fault period under the safety constraint of maintaining the heat balance of the power semiconductor and turning off overvoltage.

Although a few embodiments of the present disclosure have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined in the claims and their equivalents, and in which features of different embodiments may be combined to form new embodiments.

Claims

1. A control method of a voltage source type wind generating set is characterized by comprising the following steps:

obtaining the phase of grid-connected point voltage and grid-connected point current of a wind generating set;

determining the phase of the virtual internal potential of the wind generating set according to the phase of the grid voltage of the grid-connected point;

obtaining the amplitude of the virtual internal potential of the wind generating set;

generating a first modulation signal based on the amplitude and phase of the virtual internal potential;

in response to the grid-connected point current being greater than a first preset threshold, superimposing a voltage deviation on the first modulation signal to obtain a second modulation signal;

generating a first drive signal based on the second modulation signal;

controlling the operation of a grid-side converter of the wind generating set by using the first driving signal during the short circuit of the power grid,

wherein the voltage deviation is obtained by multiplying a predetermined virtual impedance by the grid-connected point current.

2. The control method of a voltage source type wind turbine generator set according to claim 1, characterized by further comprising: and in response to the grid-connected point current being larger than a first preset threshold and the grid-connected point voltage being lower than a second preset threshold, maintaining the phase and amplitude of the virtual internal potential as the phase and amplitude before the grid short circuit during the grid short circuit.

3. The control method of a voltage source type wind turbine generator set according to claim 1, characterized by further comprising: and in response to the condition that the grid-connected point current is larger than a first preset threshold and the grid-connected point power grid voltage is lower than a second preset threshold, controlling a machine side converter of the wind generating set to operate during the short circuit of the power grid so as to keep the direct-current bus voltage of the wind generating set stable.

4. The control method of a voltage source type wind turbine generator set according to claim 1, characterized by further comprising: and in response to the grid-connected point current being larger than a first preset threshold and the grid-connected point power grid voltage being lower than a second preset threshold, reducing the starting voltage of a brake unit of a converter of the wind generating set.

5. The control method of a voltage source type wind turbine generator set according to any one of claims 1 to 4, characterized by further comprising: and in response to the grid-connected point current being larger than a first preset threshold and the grid-connected point power grid voltage being lower than a second preset threshold, reducing the frequency of the first driving signal.

6. The method for controlling a voltage source type wind power plant according to claim 1, wherein the step of determining the phase of the virtual internal potential of the wind power plant according to the phase of the grid-connected point voltage comprises: and determining the phase of the virtual internal potential of the wind generating set according to the phase of the grid voltage of the grid-connected point, the torque/power instruction value received from the main controller and the active power measured value of the wind generating set.

7. The method for controlling a wind power plant of the voltage source type according to claim 6, wherein the step of determining the phase of the virtual internal potential of the wind power plant based on the phase of the grid-connected point voltage, the torque/power command value received from the master controller and the active power measurement value of the wind power plant comprises:

performing PI regulation on a difference between the torque/power command value and an active power measurement value of the wind turbine generator set to obtain an angular frequency,

and calculating the angular frequency by taking the phase of the grid-connected point grid voltage as an integral value of an initial value so as to determine the phase of the virtual internal potential of the wind generating set.

8. The control method of a voltage source type wind turbine generator set according to claim 1, wherein the step of obtaining the magnitude of the virtual internal potential of the wind turbine generator set comprises:

and performing PI regulation on the difference between a reactive/voltage command value received from a main controller and a voltage feedback value of a converter of the wind generating set to obtain the amplitude of the virtual internal potential.

9. A control device of a voltage source type wind turbine generator system, characterized by comprising:

the grid voltage phase detection unit is used for obtaining the phase of grid voltage of a grid-connected point of the wind generating set;

the synchronization unit is used for determining the phase of the virtual internal potential of the wind generating set according to the phase of the grid-connected point power grid voltage;

the internal potential amplitude determining unit is used for obtaining the amplitude of the virtual internal potential of the wind generating set;

a modulation unit that generates a first modulation signal based on an amplitude and a phase of the virtual internal potential and superimposes a voltage deviation to the first modulation signal in response to the grid-connected point current being greater than a first preset threshold to obtain a second modulation signal and generates a first drive signal based on the second modulation signal;

a grid-side converter control unit for controlling the operation of the grid-side converter of the wind generating set during the grid short circuit period by using the first driving signal,

10. The control device of a voltage source type wind turbine generator set according to claim 9, characterized by further comprising: and the machine side converter controller is configured to respond to the grid-connected point current being larger than a first preset threshold and the grid-connected point power grid voltage being lower than a second preset threshold, and control the machine side converter of the wind generating set to operate during the short circuit of the power grid so as to keep the direct current bus voltage of the wind generating set stable.

11. The control device of a voltage source type wind turbine generator set according to claim 9 or 10, wherein the modulation unit is configured to: and in response to the grid-connected point current being larger than a first preset threshold and the grid-connected point voltage being lower than a second preset threshold, maintaining the phase and amplitude of the virtual internal potential as the phase and amplitude before the grid short circuit during the grid short circuit.

12. The control device of a voltage source type wind turbine generator set according to claim 9, characterized by further comprising: a brake control unit configured to reduce a starting voltage of a brake unit of a converter of the wind turbine generator set in response to the grid-connected point current being greater than a first preset threshold and the grid-connected point grid voltage being lower than a second preset threshold.

13. The control device of a voltage source type wind turbine generator set according to claim 9, wherein the modulation unit is configured to: and in response to the grid-connected point current being larger than a first preset threshold and the grid-connected point power grid voltage being lower than a second preset threshold, reducing the frequency of the first driving signal.

14. A computer-readable storage medium storing a computer program, characterized in that the computer program, when executed by a processor, implements the control method according to any one of claims 1 to 8.

15. A controller, characterized in that the controller comprises:

a processor;

a memory storing a computer program which, when executed by the processor, implements the control method of the voltage source type wind turbine generator set according to any one of claims 1 to 8.

16. A wind park comprising a control device of a voltage source type wind park according to any one of claims 9 to 13.