CN115800369A - Multi-wind-farm negative-sequence current control method and system suitable for flexible direct grid connection - Google Patents

Multi-wind-farm negative-sequence current control method and system suitable for flexible direct grid connection Download PDF

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CN115800369A
CN115800369A CN202211534156.9A CN202211534156A CN115800369A CN 115800369 A CN115800369 A CN 115800369A CN 202211534156 A CN202211534156 A CN 202211534156A CN 115800369 A CN115800369 A CN 115800369A
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李英彪
胡家兵
严佳男
林磊
时晓洁
林晨升
李馥琦
朱建行
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Huazhong University of Science and Technology
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Abstract

The invention provides a multi-wind-farm negative-sequence current control method and system suitable for soft-direct grid connection, and belongs to the technical field of power electronic systems. Obtaining a negative sequence voltage error amount by setting the negative sequence voltage command value of each fan PCC to be 0, obtaining a reference value of a current inner loop through a proportion link, and obtaining a final inner loop current reference value through a proportion amplitude limiter; and an inner loop current controller is utilized to enable the inner loop current to track the reference value of the inner loop current in real time and generate the negative sequence modulation voltage of the GSC. The invention introduces a negative sequence voltage proportion control link in GSCs. The suppression method enables all the fans and filters thereof in each wind power plant to be equivalent to a resistor, and the resistance value of the resistor is determined by a proportionality coefficient, so that the redistribution of negative-sequence current in GSCs is realized. By this control method, the negative-sequence current can be equally distributed among the GSCs, thereby achieving suppression of the overcurrent.

Description

Multi-wind-farm negative-sequence current control method and system suitable for flexible direct grid connection
Technical Field
The invention belongs to the technical field of power electronic systems, and particularly relates to a multi-wind-farm negative-sequence current control method and system suitable for flexible direct grid connection.
Background
With the proposal of carbon peak-reaching and carbon neutralization targets, renewable energy sources typified by wind energy have been further developed. A high-voltage direct current transmission system (MMC-HVDC) based on a modular multilevel converter provides an economic and effective mode for large-scale offshore and onshore wind power plant grid connection. With the increase of the permeability of wind power, it is very important that a wind power plant does not disconnect from the grid and realize fault ride-through during a fault. However, power electronics have low over-current capability and may not be able to withstand the impact of a fault.
Generally, a grid-connected voltage source converter controls a negative sequence current to be 0, which is a method for effectively eliminating the overcurrent risk. However, for the wind power output system shown in fig. 1, if both the MMC and the Grid Side Converters (GSCs) adopt a control strategy of controlling the negative sequence current to be 0, there will be no negative sequence path in the system. In this case, the MMC would lose control of the positive sequence current, and thus the positive sequence current of the MMC would be forced to be the same as that of the GSC. During a fault, GSC active and reactive currents may increase due to voltage drop and voltage support, and cause current saturation thereof. In addition, since the total capacity of the GSCs is larger than that of the MMC in practical engineering, the saturation of the GSC current may further cause the MMC to overcurrent. Therefore, it is not feasible to conventionally control the MMC and the GSC to control the negative-sequence current to 0 at the same time. Therefore, to avoid over-currents and meet fault-ride-through requirements, the negative-sequence current needs to be reasonably controlled between the MMC and the multiple GSCs, leaving enough negative-sequence paths.
In order to solve the problem of negative-sequence current distribution between the MMC and the multiple GSCs, the literature proposes that the negative-sequence current of the GSCs is controlled to be 0, and the MMC provides a negative-sequence path, but the MMC still has the overcurrent risk. Subsequently, to eliminate the MMC overcurrent risk, the negative-sequence current of the MMC is limited to ensure that the positive-sequence current algebraic sum does not exceed the total limit value I mlim . The advantage of this control is that the negative-sequence current in the system is concentrated into the MMC and the control strategy is relatively simple. However, reducing the positive sequence current to provide more negative sequence current weakens the networking capability of the MMC and reduces the transient synchronization stability of the system. Furthermore, when the fault is deep and close to the MMC, the negative sequence path will become very narrow, or even no negative sequence path. Conversely, decreasing the positive sequence current of the GSC will enhance stability instead. Therefore, there is a document that the MMC side controls the negative sequence current to provide a negative sequence path for the 0,gsc side. But it is not correct to do so to equate all wind farms to one wind turbine. Compared with a single-fan system, the multi-fan system makes the fault characteristic more complicated. And negative sequence current sharing among multiple GSCs can cause negative sequence overcurrents.
Disclosure of Invention
The invention aims to provide a multi-wind farm negative sequence current control method and system suitable for flexible direct-current grid connection, and aims to solve the problem of overcurrent caused by negative sequence current distribution among multiple wind farms during an asymmetric fault period.
In order to achieve the above object, the present invention provides a negative sequence current control method for a multiple wind farm suitable for grid-connected flexible-direct current, including the following steps:
1) Setting a negative sequence voltage command value d and a q-axis component of a Point of Common Coupling (PCC) of each fan
Figure BDA0003975547830000021
And
Figure BDA0003975547830000022
are both 0, and are subtracted by d and q axes of the actual value of the negative sequence voltage of the PCC pointComponent(s) of
Figure BDA0003975547830000023
And
Figure BDA0003975547830000024
thereby obtaining an error amount;
2) The error amount passes through a proportion link to obtain a reference value of the current inner loop, and in order to prevent the current of the inner loop from exceeding the current capacity, the obtained reference value passes through a proportion amplitude limiter so as to obtain a final reference value of the current of the inner loop;
3) And an inner loop current controller is utilized to enable the inner loop current to track the inner loop current reference value in real time and generate the negative sequence modulation voltage of the GSC.
Further, the inner loop current reference value is:
Figure BDA0003975547830000031
Figure BDA0003975547830000032
wherein the content of the first and second substances,
Figure BDA0003975547830000033
represents the PCC point voltage of each fan, i =1,2,3, \8230, N is the number of fans,
Figure BDA0003975547830000034
indicating the negative sequence current of the fan, the superscript "+" indicating the command value, the subscripts "d", "q" indicating the dq axis component, respectively, K i Is a scaling factor. Wherein the proportionality coefficient K i The following two constraints are satisfied:
1) In order to distribute the negative sequence current flowing into each fan according to the overcurrent capacity of the fan, the impedance of each branch is equal per unit value, namely
Figure BDA0003975547830000035
In the formula (I), the compound is shown in the specification,
Figure BDA0003975547830000036
the impedance of the ith wind power plant branch under the negative-sequence current suppression method comprises a feeder line, a transformer and an equivalent filter of a wind power plant.
2) In order to prevent the negative sequence current flowing into the corresponding branch wind power plant from exceeding the amplitude limit value when the feeder line fails, namely:
Figure BDA0003975547830000037
in the formula (I), the compound is shown in the specification,
Figure BDA0003975547830000038
in order to be able to detect a feeder fault voltage,
Figure BDA0003975547830000039
is the impedance of the feeder line on the fan side,
Figure BDA00039755478300000310
impedance of transformer, R ei Is an equivalent impedance.
Further, the limiting value of the inner ring proportional limiter is:
Figure BDA00039755478300000311
wherein, I wlim For the total limiting value of the wind farm current, I mlim Is the MMC current total amplitude limit value.
The invention provides a multi-wind farm negative sequence current control system suitable for soft-direct grid connection, which comprises:
an error acquisition module for setting the d and q axis components of the PCC point negative sequence voltage instruction value of each fan
Figure BDA00039755478300000312
And
Figure BDA00039755478300000313
are both 0, and are subtracted by the d-and q-axis components of the actual value of the negative sequence voltage of the PCC point
Figure BDA00039755478300000314
And
Figure BDA00039755478300000315
thereby obtaining an error amount;
an inner loop current reference value obtaining module, configured to enable the error amount to pass through a proportional link to obtain a reference value of a current inner loop, and enable the reference value to pass through a proportional limiter, so as to obtain a final inner loop current reference value;
and the negative sequence modulation module is used for enabling the inner loop current to track the inner loop current reference value in real time by utilizing the inner loop current controller and generating the negative sequence modulation voltage of the GSC.
Through the technical scheme, compared with the prior art, the invention can obtain the following advantages
Has the advantages that:
(1) According to the control method, the negative sequence current flowing through the wind power plants is limited from two dimensions, and firstly, the electric distance from each wind power plant to a confluence point is compensated by using the design of equivalent impedance, so that the negative sequence current is distributed in each fan according to the capacity; and secondly, the design of the amplitude limiter ensures that the negative sequence current of each fan does not exceed the amplitude limiting value, and when the negative sequence current exceeds the amplitude limiting value, the amplitude limiter limits the reference value of the negative sequence current to the amplitude limiting value to prevent the negative sequence overcurrent, so that the amplitude limiter dynamically improves the equivalent impedance essentially.
(2) The control method provided by the invention only depends on the design of equivalent impedance and amplitude limiting value of the amplitude limiter, does not need to judge the occurrence or exit of faults, has automation and self-adaptability, and can avoid additional cost brought by communication and unstable factors brought by communication delay.
(3) Although the fan and the filter thereof are equivalent to the resistor, the control method provided by the invention does not generate extra power loss in normal operation.
(4) The control method provided by the invention has strong applicability, and can be suitable for all fault types, all fault positions and all fault depths.
Drawings
FIG. 1 is a schematic diagram of a flexible DC delivery system for multiple fans with negative sequence current control.
Fig. 2 (a) is a single-phase earth fault steady-state equivalent sequence circuit occurring on the main line.
Fig. 2 (b) is a single-phase earth fault steady-state equivalent sequence circuit occurring on the feeder.
Fig. 3 is a block diagram of a negative-sequence current suppression method provided by the present invention.
Fig. 4 (a) is an equivalent negative sequence network where a fault occurs on the main line under the proposed suppression method.
Fig. 4 (b) is an equivalent negative sequence network where a fault occurs on the feeder under the proposed suppression method.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the respective embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The invention provides a multi-wind-farm negative-sequence current control method suitable for flexible-direct grid connection, which comprises the following steps of:
1) Setting a negative sequence voltage command value d and a q-axis component of a Point of Common Coupling (PCC) of each fan
Figure BDA0003975547830000051
And
Figure BDA0003975547830000052
are all 0, and are respectively subtracted by d-axis and q-axis components of the actual value of the negative sequence voltage of the PCC point
Figure BDA0003975547830000053
And
Figure BDA0003975547830000054
thereby obtaining an error amount;
2) The error amount passes through a proportion link to obtain a reference value of the current inner loop, and in order to prevent the current of the inner loop from exceeding the current capacity, the obtained reference value passes through a proportion amplitude limiter so as to obtain a final reference value of the current of the inner loop;
3) And an inner loop current controller is utilized to enable the inner loop current to track the reference value of the inner loop current in real time and generate the negative sequence modulation voltage of the GSC.
For simplicity of analysis without loss of generality, each wind farm is equivalent to one wind turbine, and for simplicity of description, four wind farms are taken as an example for description, as shown in fig. 1. The alternating current system comprises a network-forming MMC and a network-following GSCs, and the adopted Negative Sequence Current Control (NSCC) strategy is as follows: the MMC controls the negative sequence current to provide a negative sequence path for 0,GSCs. A proportional limiter is applied in MMC and GSC to avoid overcurrent. In FIG. 1, I mlim And I wlimi Total current limit values for MMC and each GSC, respectively; i is m And I wi Alternating currents, including positive and negative sequences, of MMC and GSC, respectively; the superscripts of "+", "" 0 "and" "are respectively positive, negative, zero sequence components and reference values; the subscripts "d" and "q" are the d-axis and q-axis components, respectively.
Taking a single-phase ground fault as an example, the system fault steady-state equivalent sequence network adopting the NSCC strategy is shown in fig. 2 (a) and fig. 2 (b), where fig. 2 (a) is a main line fault and fig. 2 (b) is a feeder fault. The MMC exhibits both current and voltage source characteristics according to a fault current. Each GSC may be equivalent to a positive sequence current source limited by its negative sequence current. In alternating current networks, Z M ，Z Fi ，Z Ti And Z filteri (i =1,2,3, 4) the impedances of the main line, the feeder line and the respective transformer and filter, respectively; z i (i =0,1,2,3,4) is the impedance of the branch, including the main line or feeder, the transformer and the filter (branches 1-4). I.C. A M ，I F2 ，E M And E F2 Fault currents and fault voltages on the main line and feeder line, respectively.
When a fault occurs on a main line, a mathematical model of negative sequence current distribution is established, and the mathematical model is as follows:
Figure BDA0003975547830000061
wherein the content of the first and second substances,
Figure BDA0003975547830000062
the negative-sequence current flowing into each GSC is:
Figure BDA0003975547830000063
the fault occurs on the feeder line, taking F2 as an example, a mathematical model of negative sequence current distribution is established, which is:
Figure BDA0003975547830000064
wherein, the first and the second end of the pipe are connected with each other,
Figure BDA0003975547830000065
and
Figure BDA0003975547830000066
satisfies the following conditions:
Figure BDA0003975547830000067
the negative-sequence current flowing into each GSC is:
Figure BDA0003975547830000071
it can be seen that the negative sequence current distributed to each GSC is related to the fault condition as well as the ac network.
For convenience of description, it is assumed that
Figure BDA0003975547830000072
When a fault occurs in the main line, the negative-sequence current flowing into the GSC is inversely proportional to the branch impedance, i.e.
Figure BDA0003975547830000073
Likewise, when a fault occurs on F2, the negative-sequence current flowing into the other GSCs is inversely proportional to the branch impedance, i.e.
Figure BDA0003975547830000074
Figure BDA0003975547830000077
Depending on the location of the fault.
The magnitude of the negative-sequence current flowing into the GSCs is therefore
Figure BDA0003975547830000075
Based on the above analysis, a conclusion can be drawn: the smaller the branch impedance, the greater the risk of GSC over-current. Obviously, it is possible to cut off the corresponding overcurrent branch, but this does not meet the requirements of the grid codes. Therefore, in order to cross the asymmetric fault, it is necessary to propose an over-current suppression method implemented by only the GSC controller.
To avoid over-currents, the negative-sequence current of each GSC should be controlled at its negative-sequence current limit value
Figure BDA0003975547830000076
The following. Introducing a negative sequence voltage ratio outer loop, as shown in FIG. 3, where V wsi Is the PCC point voltage of the GSC. In this way, the GSC changes from a passively sinking negative-sequence current to an actively controlling negative-sequence current. Neglecting in currentThe loop adjusts the time, the mathematical description of the controller is:
Figure BDA0003975547830000081
wherein K i (i =1,2,3,4) is a proportionality coefficient. In conjunction with the above equation, the negative-sequence current for each GSC where a fault occurs on the main line is:
Figure BDA0003975547830000082
the negative sequence current for each GSC where the fault occurred on F2 is:
Figure BDA0003975547830000083
thus, the impedance of branches 1-4 is converted by control to:
Figure BDA0003975547830000084
it can be seen that each GSC including its filter can be equivalently a resistor R ei Resistance value of 1/K i As shown in fig. 4 (a) and 4 (b). Similarly, the negative-sequence current flowing into the GSCs is inversely proportional to the branch impedance
Figure BDA0003975547830000085
The width of the negative sequence path can be adjusted by the proportionality coefficient, and the redistribution of the negative sequence current among the GSCs can be realized. Therefore, in order to eliminate the overcurrent risk, it is necessary to select an appropriate scaling factor.
In order to distribute the negative-sequence current flowing into each GSC according to its overcurrent capability, the per-unit basis value is taken as the capacity of each GSC. At per unit value, the negative-sequence current flowing into the GSC should be equal, which is the first constraint. Therefore, the impedances of branches 1-4 should satisfy:
Figure BDA0003975547830000086
furthermore, in order to avoid excessive GSC currents in the respective branches at feeder faults, the negative sequence currents should not exceed their limiting values, which is a second constraint, namely
Figure BDA0003975547830000091
The design of changing the proportionality coefficient needs to be designed under the most serious working condition, and generally, the design is taken
Figure BDA0003975547830000098
The above description is only explained on the wind farm level, but in practical engineering it is necessary to exert control over the wind turbines in a wind farm. In order to simplify the design process, the equivalent impedance of each wind turbine in the wind farm is designed to be the same value. However, within the wind farm, the wind turbines are usually distributed in a chain manner, and the electrical distance from each wind turbine to the confluence point is different, so that the over-current of some wind turbines can be caused due to the uneven distribution of the negative-sequence current within the wind farm. For small wind farms, this difference can be approximately ignored; for a large wind farm, the difference of the electrical distances cannot be ignored, and a limiter needs to be further added to limit the negative sequence current reference value, so that overcurrent of each fan in the wind farm is prevented.
To simplify the analysis, it is assumed that the over-current capability of all GSCs is equal, i.e., the total current limit value (I) of each GSC wlim ) And negative sequence current limit value
Figure BDA0003975547830000092
And are equal. The most severe operating condition, i.e. the MMC exhibiting current source characteristics, should be considered when designing the clipping value. According to kirchhoff's current law, the maximum negative-sequence current of the GSC at different faults (single-phase earth fault, phase-to-phase fault and two-phase earth fault) is the algebraic sum of the positive-sequence currents of the MMC and the GSC, i.e. the
Figure BDA0003975547830000093
In order to be able to sink all negative-sequence currents,
Figure BDA0003975547830000094
should not be less than the maximum negative-sequence current, i.e.
Figure BDA0003975547830000095
In order to maximize the delivered positive sequence current,
Figure BDA0003975547830000096
should be as small as possible, i.e.
Figure BDA0003975547830000097
It should be noted that the above design only gives the lower limit values of the equivalent resistance and the limiter limit value, and the range of the equivalent resistance and the limiter limit value can be further limited according to other requirements of the system.
It will be understood by those skilled in the art that the foregoing is only an exemplary embodiment of the present invention, and is not intended to limit the invention to the particular forms disclosed, since various modifications, substitutions and improvements within the spirit and scope of the invention are possible and within the scope of the appended claims.

Claims (8)

1. The multi-wind-farm negative-sequence current control method suitable for the flexible direct grid connection is characterized by comprising the following steps of:
1) Setting the negative sequence voltage command value d and q axis components of each fan PCC
Figure FDA0003975547820000011
And
Figure FDA0003975547820000012
are both 0, and are subtracted by the d-and q-axis components of the actual value of the negative sequence voltage of the PCC point
Figure FDA0003975547820000013
And
Figure FDA0003975547820000014
thereby obtaining an error amount;
2) Enabling the error amount to pass through a proportion link to obtain a reference value of a current inner loop, and enabling the reference value to pass through a proportion amplitude limiter to obtain a final reference value of the current inner loop;
3) And an inner loop current controller is utilized to enable the inner loop current to track the reference value of the inner loop current in real time and generate the negative sequence modulation voltage of the GSC.
2. The method of claim 1, wherein the inner loop current reference value is:
Figure FDA0003975547820000015
Figure FDA0003975547820000016
wherein the content of the first and second substances,
Figure FDA0003975547820000017
represents the PCC point voltage of each fan, i =1,2,3, \8230, N is the number of fans,
Figure FDA0003975547820000018
indicating the negative sequence current of the fan, the superscript "+" indicating the command value, the subscripts "d", "q" indicating the dq axis component, respectively, K i Is a scaling factor.
3. The method of claim 1, wherein the scaling factor K is a negative sequence current of the wind farm i The following two constraints are satisfied:
1) The negative sequence current flowing into each fan is distributed according to the overcurrent capacity of the fan, and the impedance of each branch is equal under a per unit value, namely:
Figure FDA0003975547820000019
in the formula (I), the compound is shown in the specification,
Figure FDA00039755478200000110
impedance of an ith wind power plant branch circuit comprising a feeder line, a transformer and an equivalent filter of a wind power plant, wherein i =1,2,3, \ 8230;
2) When a feeder line fails, the negative sequence current flowing into the corresponding branch wind power plant should not exceed the amplitude limit value thereof, namely:
Figure FDA0003975547820000021
in the formula (I), the compound is shown in the specification,
Figure FDA0003975547820000022
in order to be able to detect a feeder fault voltage,
Figure FDA0003975547820000023
is the impedance of the feeder line on the fan side,
Figure FDA0003975547820000024
impedance of transformer, R ei Is an equivalent impedance.
4. The method of claim 1, wherein the limiting value of the inner-loop proportional limiter is:
Figure FDA0003975547820000025
wherein, I wlim For the total limiting value of the wind farm current, I mlim The MMC current total amplitude limit value.
5. Many wind farm negative sequence current control system suitable for gentle straight and network that is incorporated into power networks, its characterized in that includes:
an error acquisition module for setting the d and q axis components of the PCC point negative sequence voltage instruction value of each fan
Figure FDA0003975547820000026
And
Figure FDA0003975547820000027
are all 0, and are respectively subtracted by d-axis and q-axis components of the actual value of the negative sequence voltage of the PCC point
Figure FDA0003975547820000028
And
Figure FDA0003975547820000029
thereby obtaining an error amount;
a proportion link for obtaining a reference value of the current inner loop, and an inner loop current reference value obtaining module for enabling the error amount to pass through a proportion limiter so as to obtain a final inner loop current reference value;
and the negative sequence modulation module is used for enabling the inner loop current to track the inner loop current reference value in real time by utilizing the inner loop current controller and generating the negative sequence modulation voltage of the GSC.
6. The negative sequence current control system of claim 5, wherein the inner loop current reference value is:
Figure FDA00039755478200000210
Figure FDA00039755478200000211
wherein, the first and the second end of the pipe are connected with each other,
Figure FDA00039755478200000212
representing the PCC voltage for each fan, i =1,2,3, \ 8230, N, N being the number of fans,
Figure FDA00039755478200000213
indicating the negative sequence current of the fan, the superscripts "+" indicating the command values, the subscripts "d", "q" indicating the dq axis components, respectively, K i Is a scale factor.
7. A multi-farm negative-sequence current control system according to claim 5, wherein the proportionality coefficient K i The following two constraints are satisfied:
1) The negative sequence current flowing into each fan is distributed according to the overcurrent capacity of the fan, and the impedance of each branch is equal under a per unit value, namely:
Figure FDA0003975547820000031
in the formula (I), the compound is shown in the specification,
Figure FDA0003975547820000032
the impedance of the ith wind power plant branch comprises a feeder line, a transformer and an equivalent filter of a wind power plant, i =1,2,3, \8230, and N are the number of fans;
2) When a feeder line fails, the negative sequence current flowing into the corresponding branch wind power plant should not exceed the amplitude limit value thereof, namely:
Figure FDA0003975547820000033
in the formula (I), the compound is shown in the specification,
Figure FDA0003975547820000034
is the voltage at which the feeder line fails,
Figure FDA0003975547820000035
is the impedance of the feeder line on the fan side,
Figure FDA0003975547820000036
impedance of transformer, R ei Is an equivalent impedance.
8. The negative-sequence current control system of claim 5, wherein the inner-loop proportional limiter limit value is:
Figure FDA0003975547820000037
wherein, I wlim For the wind farm current total limiting value, I mlim Is the MMC current total amplitude limit value.
CN202211534156.9A 2022-12-01 2022-12-01 Multi-wind-farm negative-sequence current control method and system suitable for flexible direct grid connection Pending CN115800369A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117477642A (en) * 2023-10-30 2024-01-30 国家电网有限公司华东分部 Asymmetric fault ride-through control method and device for multiple wind power plants and electronic equipment

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115051404A (en) * 2022-04-13 2022-09-13 国网浙江省电力有限公司湖州供电公司 Alternating voltage control method of high-voltage network-building type current converter

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115051404A (en) * 2022-04-13 2022-09-13 国网浙江省电力有限公司湖州供电公司 Alternating voltage control method of high-voltage network-building type current converter

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
JIANAN YAN: "Overcurrent Suppression Method for Multiple Wind Farms Connected to MMC-HVDC", IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS Ⅱ, vol. 69, no. 11, 21 June 2022 (2022-06-21), pages 4473, XP011925483, DOI: 10.1109/TCSII.2022.3185070 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117477642A (en) * 2023-10-30 2024-01-30 国家电网有限公司华东分部 Asymmetric fault ride-through control method and device for multiple wind power plants and electronic equipment

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