Current control of a wind park
A method for controlling a current in a wind park is provided. The wind park includes at least one wind turbine and at least one current generator. The method includes detecting a grid irregularity, determining an optimal current to be provided at a predetermined location in the wind park during the grid irregularity and determining a corresponding current to be generated from the at least one current generator so as to provide the optimal current at the predetermined location. The corresponding current is determined based on at least an impedance value between the at least one current generator and the predetermined location.
1. A method for controlling a current in a wind park comprising at least one wind turbine, wherein the wind park comprises at least one current generator, the method comprising:
detecting a grid irregularity;
determining an optimal reactive current to be provided at a predetermined location in the wind park during the grid irregularity; and
determining, using one or more processors associated with a wind turbine controller, a corresponding active current to be generated from the at least one current generator so as to provide the optimal reactive current at the predetermined location, characterized in that the corresponding active current is determined based on at least an impedance value between the current generator and the predetermined location.
2. The method according to claim 1 , wherein the predetermined location comprises a point of common coupling of the wind park to a grid or utility system.
3. The method according to claim 1 , wherein the grid irregularity comprises a low voltage event in the grid.
4. The method according to claim 1 , wherein said optimal reactive current follows a predetermined pattern of injected reactive current towards a voltage level during the grid irregularity.
5. The method according to claim 1 , wherein the at least one current generator comprises a reactive current generator for generating a reactive current and an active current generator for generating the active current.
6. The method according to claim 5 , wherein the active current is determined based on the following expression:
I
ds
_
opt
=
R
X
(
I
qs
±
v
G
K
G
Z
2
+
4
X
2
(
K
wf
2
-
K
wf
)
)
,
wherein
I d — opt is the active current generated by the active current generator,
I qs is the reactive current generated by the reactive current generator,
R is a resistance between the wind turbine and the predetermined location
Z is the impedance between the wind turbine and the predetermined location,
X is a reactive impedance between the wind turbine and the predetermined location,
V G is the amplitude of the voltage at the grid, and
K G and K wf are grid constants.
7. The method according to claim 5 , wherein the wind turbine comprises at least one of the active current generator and the reactive current generator.
8. The method according to claim 5 , wherein the reactive current generator comprises a static synchronous compensator (STATCOM).
9. The method according to claim 5 , wherein the active current generator comprises an energy storage unit.
10. A wind park comprising:
at least one wind turbine; and
a wind park controller adapted to do the following:
detect a grid irregularity;
determine an optimal reactive current to be provided at a predetermined location in the wind park during the grid irregularity; and
determine a corresponding active current to be generated from a current generator so as to provide the optimal reactive current at the predetermined location, wherein the corresponding active current is determined based on at least an impedance value between the current generator and the predetermined location.
11. The wind park according to claim 10 , wherein the predetermined location comprises a point of common coupling of the wind park to a grid or utility system.
12. The wind park according to claim 10 , wherein the wind park controller is adapted to detect a low voltage event in the grid.
13. The wind park according to claim 10 , wherein said optimal reactive current follows a predetermined pattern of injected reactive current towards a voltage level during the grid irregularity.
14. The wind park according to claim 10 , wherein the current generator comprises a reactive current generator for generating a reactive current and an active current generator for generating the active current.
15. The wind park according to claim 14 , wherein the wind turbine comprises at least one of the active current generator and the reactive current generator.
16. The wind park according to claim 14 , further comprising a static synchronous compensator (STATCOM), wherein the STATCOM is the reactive current generator for generating the reactive current.
17. The wind park according to claim 14 , further comprising an energy storage unit, wherein the energy storage unit is the active current generator for generating the active current.
18. A controller for use in a wind park comprising at least one wind turbine, the controller comprising one or more computer processors adapted to perform at least the following:
detect a grid irregularity;
determine an optimal reactive current to be provided at a predetermined location in the wind park during the grid irregularity; and
determine a corresponding active current to be generated from a current generator so as to provide the optimal reactive current at the predetermined location, wherein the corresponding active current is determined based on at least an impedance value between the current generator and the predetermined location.