US 12,009,771 B1Granted

Doubly fed induction generator speed control system and method for controlling the system

AssigneeKing Fahd University of Petroleum and Minerals

InventorsMuhammad Khalid, Mohammad Ali

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Abstract

A doubly fed induction generator (DFIG) speed control system is provided. The system includes a wind turbine and a wound rotor induction generator connected to the wind turbine through a drive train system and to a power grid. The system further includes a back-to-back voltage source converter (VSC) with a rotor side converter (RSC) and a grid side converter (GSC). The RSC is connected to the wound rotor induction generator and the GSC is connected to the power grid. A wind profile sensor measures a wind profile and a VSC controller provides control to the RSC and the GSC. The VSC controller applies a nonsingular fast terminal sliding mode control (NSFTSMC) scheme at the RSC at least partially based on the received wind profile to stabilize a rotor speed of the wound rotor induction generator.

Claims18

Dependent claims

A doubly fed induction generator (DFIG) speed control system, comprising:

a wind turbine;
a wound rotor induction generator configured to connect with the wind turbine through a drive train system;
the wound rotor induction generator is further configured to connect to a power grid;
a back-to-back voltage source converter (VSC) with a rotor side converter (RSC) and a grid side converter (GSC), wherein the RSC is connected to the wound rotor induction generator and the GSC is connected to the power grid;
a wind profile sensor configured to measure a wind profile;
and
a VSC controller configured to provide control to the RSC and the GSC;
wherein the VSC controller is configured to apply a nonsingular fast terminal sliding mode control (NSFTSMC) scheme at the RSC at least partially based on the received wind profile to stabilize a rotor speed of the wound rotor induction generator to a base speed and to achieve a shorter stabilizing time than a conventional proportional integral controller;
wherein the nonsingular fast terminal sliding mode control (NSFTSMC) scheme is expressed as:
u
=
-
a
1
b
⁢
x
2
-
❘
"\[LeftBracketingBar]"
x
2
❘
"\[RightBracketingBar]"
2
-
ξ
2
⁢
sign
(
x
2
)
b
⁢
c
2
⁢
ζ
2
⁢
(
x
2
+
c
1
⁢
ξ
1
⁢
❘
"\[LeftBracketingBar]"
x
1
❘
"\[RightBracketingBar]"
ξ
1
-
1
⁢
x
2
)
-
α
1
⁢
s
-
α
2
⁢
❘
"\[LeftBracketingBar]"
s
❘
"\[RightBracketingBar]"
β
⁢
sign
(
s
)
,
where u is the control input,
a
1
=
-
B
J
,
b
=
k
t
⁢
k
1
J
,
where B is the friction coefficient, J is the moment of inertia, kt and k1 are gain constants, α1>0, α2>0, and β∈(0,1) is the pitch angle;
x1 is a first order mechanical dynamic equation x1=θ*r−θr where θ*r is the desired angular position and θr is the angular position of the wind turbine;
x2 is a second order mechanical dynamic equation
x
2
=
-
(
T
e
-
T
L
)
⁢
1
Js
+
B
where TL is the disturbance load torque and Te is the electromechanical control torque;
and
s is the nonsingular fast terminal sliding surface (NSFTSS) expressed as:
s=x1+c1|x1|ξ1 sign(x1)+c2|x2|ξ2 sign(x2),
where c1 and c2 are positive coefficients of NSFTSS s∈ and ξ1 and ξ2 are the auxiliary state variables of observer where ξ2∈(1, 2) and ξ1>ξ2.

126 more elements

A method for controlling a doubly fed induction generator (DFIG) speed control system, comprising:

measuring a wind profile;
and
applying a nonsingular fast terminal sliding mode control (NSFTSMC) scheme to the DFIG speed control system, the DFIG speed control system is configured to include:
a wind turbine;
a wound rotor induction generator configured to connect with the wind turbine through a drive train system and connect to a power grid;
a back-to-back voltage source converter (VSC) with a rotor side converter (RSC) and a grid side converter (GSC), wherein the RSC is connected to the wound rotor induction generator and the GSC is connected to the power grid;
and
a VSC controller;
wherein the NSFTSMC scheme is applied to stabilize a rotor speed of the wound rotor induction generator to a base speed and to achieve a shorter stabilizing time than a conventional proportional integral controller;
wherein the nonsingular fast terminal sliding mode control (NSFTSMC) scheme is expressed as:
u
=
-
a
1
b
⁢
x
2
-
❘
"\[LeftBracketingBar]"
x
2
❘
"\[RightBracketingBar]"
2
-
ξ
2
⁢
sign
(
x
2
)
b
⁢
c
2
⁢
ξ
2
⁢
(
x
2
+
c
1
⁢
ξ
1
⁢
❘
"\[LeftBracketingBar]"
x
1
❘
"\[RightBracketingBar]"
ξ
1
-
1
⁢
x
2
)
-
α
1
⁢
s
-
α
2
⁢
❘
"\[LeftBracketingBar]"
s
❘
"\[RightBracketingBar]"
β
⁢
sign
(
s
)
,
where u is the control input
a
1
=
-
B
J
,
b
=
k
t
⁢
k
1
J
,
where B is the friction coefficient, J is the moment of inertia, kt and k1 are gain constants, α1>0, α2>0, and β∈(0,1) is the pitch angle;
x1 is a first order mechanical dynamic equation x1=θ*r−θr where θ*r is the desired angular position and θr is the angular position of the wind turbine;
x2 is a second order mechanical dynamic equation
x
2
=
-
(
T
e
-
T
L
)
⁢
1
Js
+
B
where TL is the disturbance load torque and Te is the electromechanical control torque;
and
s is the nonsingular fast terminal sliding surface (NSFTSS) expressed as:
s=x1+c1|x1|ξ1 sign(x1)+c2|x2|ξ2 sign(x2),
where c1 and c2 are positive coefficients of NSFTSS s∈ and ξ1 and ξ2 are the auxiliary state variables of observer where ξ2∈(1, 2) and ξ1>ξ2.

127 more elements

A method for controlling a doubly fed induction generator (DFIG) speed control system, comprising:

measuring a wind profile;
and
applying a nonsingular fast terminal sliding mode control (NSFTSMC) scheme to stabilize a rotor speed of the DFIG to a base speed and to achieve a shorter stabilizing time than a conventional proportional integral controller, wherein the NSFTSMC scheme is expressed as:
u
=
-
a
1
b
⁢
x
2
-
❘
"\[LeftBracketingBar]"
x
2
❘
"\[RightBracketingBar]"
2
-
ξ
2
⁢
sign
(
x
2
)
b
⁢
c
2
⁢
ξ
2
⁢
(
x
2
+
c
1
⁢
ξ
1
⁢
❘
"\[LeftBracketingBar]"
x
1
❘
"\[RightBracketingBar]"
ξ
1
-
1
⁢
x
2
)
-
α
1
⁢
s
-
α
2
⁢
❘
"\[LeftBracketingBar]"
s
❘
"\[RightBracketingBar]"
β
⁢
sign
(
s
)
,
where u is the control input,
a
1
=
-
B
J
,
b
=
k
t
⁢
k
1
J
,
where B is the friction coefficient, J is the moment of inertia, kt and k1 are gain constants, α1>0, α2>0, and β∈(0,1) is the pitch angle;
x1 is a first order mechanical dynamic equation x1=θ*r−θr where θ*r is the desired angular position and θr is the angular position of the wind turbine;
x2 is a second order mechanical dynamic equation
x
2
=
-
(
T
e
-
T
L
)
⁢
1
Js
+
B
where TL is the disturbance load torque and Te is the electromechanical control torque;
and
s is the nonsingular fast terminal sliding surface (NSFTSS) expressed as:
s=x1+c1|x1|ξ1 sign(x1)+c2|x2|ξ2 sign(x2),
where c1 and c2 are positive coefficients of NSFTSS s∈, and ξ1 and ξ2 are the auxiliary state variables of observer where ξ2∈(1, 2) and ξ1>ξ2.

120 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/178,207Filed 3 Mar 2023
Granted: 11 Jun 2024
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H02P 9/007
Arrangements for controlling electric generators for the purpose of obtaining a desired output: control circuits for doubly fed generators
H02J 3/381
Arrangements for feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised…
H02J 2101/28
Dispersed power generation using renewable energy sources: wind energy
H02P 2101/15
Special adaptation of control arrangements for generators: for wind-driven turbines

Family

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