Grid-forming control method for offshore wind turbine

Patent metadata

Field	Value
Publication number	US-12567744-B2
Application number	US-202318144343-A
Country	US
Kind code	B2
Filing date	May 8, 2023
Priority date	May 7, 2022
Publication date	Mar 3, 2026
Grant date	Mar 3, 2026

Abstract

Disclosed is grid-forming control method for an offshore wind turbine, including the following steps: obtaining a grid voltage and current at a grid connection point of a wind turbine, actual values of active power and reactive power of the wind turbine, and references of the active power, the reactive power and an voltage amplitude; calculating a phase reference of a grid-side converter of the wind turbine; calculating a reference of a modulating voltage at the grid-side converter of the wind turbine in a dq rotating coordinate system; and calculating a reference of a modulating voltage at the grid-side converter in an abc static coordinate system according to the phase reference of the grid-side converter of the wind turbine and the reference of the modulating voltage in the dq rotating coordinate system. The present disclosure can control the voltage amplitude of the grid connection point by the active power of the wind turbine, and can control the voltage frequency at the grid connection point by the reactive power of the wind turbine. Furthermore, the wind turbine controlled by the present disclosure can be kept in reliable synchronous running under conditions of startup, power fluctuation, alternating current (AC) fault and the like.

First claim

The invention claimed is:

1 . A grid-forming control method for an offshore wind turbine, performed by a grid-forming system, wherein the grid-forming system is part of or in communication with the offshore wind turbine, and wherein the grid-forming control method comprises the following steps:
S 1 , obtaining a grid voltage and a current at a grid connection point of the offshore wind turbine, performing a dq decomposition on the grid voltage and the current at the grid connection point of the offshore wind turbine to separately obtain d-axis components and q-axis components of the grid voltage and the current at the grid connection point in a dq rotating coordinate system, obtaining actual values of active power, reactive power, and voltage frequency at the grid connection point of the offshore wind turbine, and obtaining references of the active power, the reactive power and the voltage amplitude at the grid connection point of the offshore wind turbine; S 2 , calculating a phase reference of a grid-side converter of the offshore wind turbine; S 3 , calculating a d-axis voltage reference-of the grid connection point of the offshore wind turbine; S 4 , calculating a d-axis current reference and a q-axis current reference of the grid connection point of the offshore wind turbine; S 5 , calculating a d-axis voltage reference and a q-axis voltage reference of a modulating voltage of the grid-side converter of the offshore wind turbine; S 6 , calculating an a-axis voltage reference, a b-axis voltage reference, and a c-axis reference of the modulating voltage in an abc static coordinate system of the grid-side converter of the offshore wind turbine; and S 7 , generating, according to the references of the modulating voltages, a corresponding control pulse for each Insulated Gate Bipolar Transistor of the grid-side converter by pulse width modulation, to control the grid-side converter of the offshore wind turbine, thereby establishing a stable alternating current voltage for the offshore wind turbine and controlling the offshore wind turbine to keep synchronous running under conditions of startup, power fluctuations, or alternating current fault.

2 . The grid-forming control method for the offshore wind turbine according to claim 1 , wherein in the step S 2 , a calculation formula for the phase reference, θ*, of the grid-side converter of the offshore wind turbine is as follows:

θ
*

=

ω

b
⁢
a
⁢
s
⁢
e

s

[

ω
+

K
G

1
+

s
⁢

K
T

⁢

(

Q
-

Q

r
⁢
e
⁢
f

)

]

where s is a Laplace operator; ω base is a basic frequency of an AC system; ω is the actual value of the voltage frequency at the grid connection point; K G and K T are a proportion parameter and time parameter of a first-order inertial controller, respectively; Q is the actual value of the reactive power of the offshore wind turbine; and Q ref is the reference of the reactive power of the offshore wind turbine.

3 . The grid-forming control method for the offshore wind turbine according to claim 1 , wherein in the step S 3 , a calculation formula for the d-axis voltage reference, U d *, of the grid connection point of the offshore wind turbine is as follows:

U
d
*

=

U

d
⁢
0

+

(

K
P

+

K
I

s

)

⁢

(

P

r
⁢
e
⁢
f

-
P

)

where U d0 is the reference of the voltage amplitude at the grid connection point of the offshore wind turbine; K P and K I are a proportion parameter and an integral parameter of an active power PI controller, respectively; s is a Laplace operator; and P ref and P are the reference and the actual value of the active power of the offshore wind turbine, respectively.

4 . The grid-forming control method for the offshore wind turbine according to claim 1 , wherein in the step S 4 , calculation formulas for the d-axis current reference, I d *, and the q-axis current reference, I q *, of the grid connection point of the offshore wind turbine are as follows:

{

I
d
*

=

-
ω

⁢

C
F

⁢

U
q

+

(

K

Assignees

• Univ South China Tech
• Electric Power Res Institute Of China Southern Power Grid Co Ltd
• South China Univ Of Technology & Electric Power Research Institute Of China Southern Power Grid Co L

Inventors

• Xiao Huangqing
• Huang Xiaowei
• Li Yan
• Huang Weihuang
• Cai Dongxiao
• Peng Faxi

Classifications

• H02J2101/28

  Wind energy · CPC title

• H02J3/36

  Arrangements for transfer of electric power between AC networks via high-voltage DC [HVDC] links; Arrangements for transfer of electric power between generators and networks via HVDC links · CPC title

• Y02E10/76

  Power conversion electric or electronic aspects · CPC title

• H02J3/381

  Dispersed generators · CPC title

• Y02E60/60

  Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD] · CPC title