# US 12,119,649 B2 · Oscillation active damping control method and system for grid-tied type-4 wind turbine generator

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- Number: US 12,119,649 B2
- Document ID: US12119649B2
- Status: Granted
- Kind: B2
- Application number: 17/828,696
- Filed: 2022-05-31
- Published: 2022-12-15
- Granted: 2024-10-15
- Earliest claimed: 2021-06-02
- Assignees: North China Electric Power University
- Applicants: North China Electric Power University
- Inventors: Jing Ma; Letian Wang; Xiangyu Li; Wangyang Du; Yitong Xu
- Web page: https://patentgrep.com/patent/US12119649B2

## CPC

- G05B 13/041: {in which a variable is automatically adjusted to optimise the performance}
- H02J 3/00142: {Oscillations concerning frequency}
- F03D 7/0284: {in relation to the state of the electric grid}
- G05B 19/042: using digital processors (G05B19/05 takes precedence)
- H02J 3/381: {Dispersed generators}
- F03D 7/0296: {to prevent, counteract or reduce noise emissions}
- F05B 2270/337: Electrical grid status parameters, e.g. voltage, frequency or power demand
- G05B 2219/2619: Wind turbines
- H02J 2101/28: Wind energy
- H02J 2103/30: Simulating, planning, modelling, reliability check or computer assisted design [CAD] of electric power networks
- Y02E 10/76: Power conversion electric or electronic aspects
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- F03D: WIND MOTORS
- F05B: INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

The application relates to an oscillation active damping control method and system for grid-tied type-4 wind turbine generator. The method comprises: based on an interconnection model of multiple subsystems, constructing a stored energy function and a dissipated energy function of a current inner loop control subsystem, and interaction energy functions between the current inner loop control subsystem and other subsystems are constructed, then establishing an energy feedback model of Type-4 wind turbine generator; when the oscillation occurs, obtaining instantaneous angular frequency of the PLL, and then based on the energy feedback model, adjusting the current reference value of the q-axis current inner loop generated by the reactive power outer loop control subsystem, to make the stored energy function decrease with time, so as to suppress the oscillation.

## Claims

### Claim 1

An oscillation active damping control method for grid-tied type-4 wind turbine generator, the grid-tied type-4 wind turbine generator comprises multiple subsystems, wherein the method comprising:
based on an interconnection model of the multiple subsystems, constructing a stored energy function and a dissipated energy function of a current inner loop control subsystem, and a first interaction energy function between the current inner loop control subsystem and a DC voltage control subsystem, a second interaction energy function between the current inner loop control subsystem and a phase lock loop subsystem, and a third interaction energy function between the current inner loop control subsystem and a reactive power outer loop control subsystem, then establishing an energy feedback model of the grid-tied type-4 wind turbine generator;
when oscillation of the grid-tied type-4 wind turbine generator occurs, obtaining instantaneous angular frequency of a phase lock loop in the phase lock loop subsystem, based on the energy feedback model, adjusting a current reference value of a q-axis current inner loop generated by the reactive power outer loop control subsystem, to make the stored energy function value decrease with time, so as to suppress the oscillation.

### Claim 2 (depends on 1)

The oscillation active damping control method for grid-tied type-4 wind turbine generator according to the claim 1, wherein constructing energy functions based on an interconnection model of the multiple subsystems, a small signal model of d-axis of the current inner loop control subsystem and a small signal model of q-axis of the current inner loop control subsystem;
the expression of the stored energy function is:
V
s
⁢
_
⁢
acc
=
1
2
⁢
L
1
(
Δ
⁢
I
1
⁢
d
2
+
Δ
⁢
I
1
⁢
q
2
)
+
1
2
⁢
C
i
(
Δ
⁢
U
id
2
+
Δ
⁢
U
iq
2
)
where Vs_acc is the stored energy function, L1 is filter inductance in the current inner loop control subsystem, ΔI1d is d-axis perturbated current in the filter inductance L1, ΔI1q is q-axis perturbated current in the filter inductance L1,
C
i
=
1
k
i
×
k
pwm
,
ki is an integral gain of a PI controller in the current inner loop control subsystem, kpwm is gain of a converter, ΔU1d is perturbated state variable in an integral link of a d-axis PI controller in the current inner loop control subsystem, ΔU1q is perturbated state variable in an integral link of a q-axis PI controller in the current inner loop control subsystem;
the expression of the dissipation energy function is:
Vd_acc=−Rp∫ΔI1d2dt−Rp∫ΔI1q2dt,
where Vd_acc is the dissipation energy function, Rp=kpΔkpwm, kp is the proportional gain of, the PI controller in the current inner loop control subsystem, kpwm is the gain of the converter;
the expression of the first interaction energy function is:
Vt_dc=∫ΔIdrefΔUiddt+∫ΔIdrefΔI1ddt,
where Vt_dc is the first interaction energy function, ΔIdref is perturbated current reference value of the d-axis current inner loop generated by the DC voltage control subsystem;
the expression of the second interaction energy function is:
Vt_pll=−k1(∫ΔθpllΔUiddt+Rp∫ΔI1ddt)+k2(∫ΔθpllΔUiqdt+Rp∫ΔθpllΔI1qdt)+k3∫ΔθpllΔI1ddt+k4∫ΔθpllΔ1qdt,
where Vt_pll is the second interaction energy function, Δθpll is perturbated phase of the phase lock loop in the phase lock loop subsystem, k1, k2, k3, and k4 are constants whose expressions are shown below:
{
k
1
=
-
I
1
⁢
q
⁢
0
k
2
=
I
1
⁢
d
⁢
0
k
3
=
-
U
pwmq
⁢
0
+
U
pccq
⁢
0
+
ω
0
⁢
L
1
⁢
I
1
⁢
d
⁢
0
k
4
=
U
pwmd
⁢
0
-
U
pccd
⁢
0
+
ω
0
⁢
L
1
⁢
I
1
⁢
q
⁢
0
,
where I1d0 is a steady-state value of d-axis current in the filter inductance L1, I1q0 is a steady-state value of q-axis current in the filter inductance L1, Upwmd0 is a steady-state value of the d-axis component of converter port voltage in the current inner loop control subsystem, Upwmq0 is a steady-state value of the q-axis component of the converter port voltage in the current inner loop control subsystem, Upccd0 is a steady-state value of d-axis voltage at a point of common coupling, Upccq0 is a steady-state value of q-axis voltage at the point of common coupling, and ω0 is rated angular frequency of the phase lock loop;
the expression of the third interaction energy function is:
Vt_q=∫ΔIqrefΔUiqdt+∫RpΔIqrefΔI1qdt,
where Vt_q is the third interaction energy function, ΔIqref is perturbated current reference value of the q-axis current inner loop generated by the reactive power outer loop control subsystem.

### Claim 3 (depends on 2)

The oscillation active damping control method for grid-tied type-4 wind turbine generator according to claim 2, wherein the small signal model of the d-axis of the current inner loop control subsystem is:
{
C
i
⁢
d
⁢
Δ
⁢
U
id
dt
=
-
Δ
⁢
I
1
⁢
d
+
F
Cd
L
1
⁢
d
⁢
Δ
⁢
I
1
⁢
d
dt
=
-
R
p
⁢
Δ
⁢
I
1
⁢
d
+
Δ
⁢
U
id
+
F
Ld
⁢
F
Cd
=
Δ
⁢
I
dref
-
k
1
⁢
Δ
⁢
θ
pll
⁢
F
Ld
=
k
3
⁢
Δθ
+
(
Δ
⁢
I
dref
-
k
1
⁢
Δθ
pll
)
,
the small signal model of the q-axis of the current inner loop control subsystem is:
{
C
i
⁢
d
⁢
Δ
⁢
U
iq
dt
=
-
Δ
⁢
I
1
⁢
q
+
F
Cq
L
1
⁢
d
⁢
Δ
⁢
I
1
⁢
q
dt
=
-
R
p
⁢
Δ
⁢
I
1
⁢
q
+
Δ
⁢
U
iq
+
F
Lq
⁢
F
Cq
=
Δ
⁢
I
qref
-
k
2
⁢
Δ
⁢
θ
pll
⁢
F
Lq
=
k
4
⁢
Δθ
pll
+
R
p
(
Δ
⁢
I
qref
+
k
2
⁢
Δθ
pll
)
.

### Claim 4 (depends on 2)

The oscillation active damping control method for grid-tied type-4 wind turbine generator according to claim 2, wherein the energy feedback model is:
Vs_acc=Vd_acc+Vt_dc+Vt_pll+Vt_q.

### Claim 5 (depends on 1)

The oscillation active damping control method for grid-tied type-4 wind turbine generator according to claim 1, wherein adjusting the current reference value of the q-axis current inner loop generated by the reactive power outer loop control subsystem according to the following compensation function:
dIqref=−Idref×∫ωplldt,
where dIqref is adjusted current reference value of the q-axis current inner loop, Idref is instantaneous current reference value of the d-axis current inner loop generated by the DC voltage control subsystem, ωpll is deviation of the angular frequency measured by the phase lock loop, that is, the deviation between the instantaneous angular frequency measured by phase lock loop and the rated angular frequency.

### Claim 6 (depends on 5)

The oscillation active damping control method for grid-tied type-4 wind turbine generator according to claim 5, wherein the deviation of the angular frequency measured by the phase lock loop and perturbated phase of the phase lock loop in the phase lock loop subsystem satisfy the following relationship:
Δθpll=∫ωplldt,
where Δθpll is perturbated phase of the phase lock loop in the phase lock loop subsystem, ωpll is the deviation of the angular frequency measured by the phase lock loop;
based on the above relationship and the compensation function, the reduction of the third interaction energy function value generated by adjusted current reference value of the q-axis current inner loop which is generated by the reactive power outer loop control subsystem is offset by the increment of the second interaction energy function value that is induced by the perturbated phase of the phase lock loop when the oscillation occurs, to make the stored energy function value decreases with time, so as to suppress the oscillation.

### Claim 7 (depends on 5)

The oscillation active damping control method for grid-tied type-4 wind turbine generator according to claim 5, wherein the oscillation comprises oscillation in sub-synchronous frequency band, from 2.5 Hz to 50 Hz, or oscillation in super-synchronous frequency band, from 50 Hz to 100 Hz.

### Claim 8

An oscillation active damping control system for grid-tied type-4 wind turbine generator, comprising:
a model building module is configured to base on an interconnection model of multiple subsystems for the grid-tied type-4 wind turbine generator, construct a stored energy function and a dissipated energy function of the current inner loop control subsystem in the multiple subsystems, and a first interaction energy function between the current inner loop control subsystem and a DC voltage control subsystem, a second interaction energy function between the current inner loop control subsystem and a phase-locked loop subsystem, and a third interaction energy function between the current inner loop control subsystem and a reactive power outer loop control subsystem, then establish an energy feedback model;
an adjustment module is configured to obtain the instantaneous angular frequency of a phase lock loop in the phase-locked loop subsystem when the oscillation of the grid-tied type-4 wind turbine generator occurs, based on the energy feedback model, adjust a current reference value of a q-axis current inner loop generated by the reactive power outer loop control subsystem, to make the value of the stored energy function decrease with time, so as to suppress the oscillation.

### Claim 9 (depends on 8)

The oscillation active damping control system for grid-tied type-4 wind turbine generator according to claim 8, wherein the adjustment module is configured to adjust a current reference value of a q-axis current inner loop generated by the reactive power outer loop control subsystem based on the following compensation function:
dIqref=−Idref×∫ωplldt,
where dIqref is adjusted current reference value of the q-axis current inner loop, Idref is instantaneous current reference value of a d-axis current inner loop generated by the DC voltage control subsystem, ωpll is deviation of angular frequency measured by the phase lock loop, that is, the deviation between the instantaneous angular frequency measured by the phase lock loop and rated angular frequency.

### Claim 10 (depends on 9)

The oscillation active damping control system for grid-tied type-4 wind turbine generator according to claim 9, wherein the oscillation active damping control system comprises a monitoring module is configured to measure the angular frequency of the phase lock loop in real time.

### Claim 11 (depends on 9)

The oscillation active damping control system for grid-tied type-4 wind turbine generator according to claim 9, wherein the energy feedback model is configured that the deviation of the angular frequency measured by the phase lock loop and perturbated phase of the phase lock loop in the phase lock loop subsystem satisfy the following relationship:
Δθpll=∫ωplldt,
where Δθpll is perturbated phase of the phase lock loop in the phase lock loop subsystem, ωpll is the deviation of the angular frequency measured by the phase lock loop;
based on the above relationship and the compensation function, the reduction of the third interaction energy function value generated by adjusted current reference value of the q-axis current inner loop which is generated by the reactive power outer loop control subsystem is offset by the increment of the second interaction energy function value that is induced by the perturbated phase of the phase lock loop when the oscillation occurs, to make the stored energy function value decreases with time, so as to suppress the oscillation.

### Claim 12 (depends on 11)

The oscillation active damping control method for grid-tied type-4 wind turbine generator according to claim 11, wherein the oscillation comprises oscillation in sub-synchronous frequency band, from 2.5 Hz to 50 Hz, or oscillation in super-synchronous frequency band, from 50 Hz to 100 Hz.

### Claim 13 (depends on 8)

The oscillation active damping control system for grid-tied type-4 wind turbine generator according to claim 8, the model building module is configured to construct energy functions based on an interconnection model of the multiple subsystems, a small signal model of d-axis of the current inner loop control subsystem and a small signal model of q-axis of the current inner loop control subsystem, wherein
expression of the stored energy function is:
V
s
⁢
_
⁢
acc
=
1
2
⁢
L
1
(
Δ
⁢
I
1
⁢
d
2
+
Δ
⁢
I
1
⁢
q
2
)
+
1
2
⁢
C
i
(
Δ
⁢
U
id
2
+
Δ
⁢
U
iq
2
)
where Vs_acc is the stored energy function, L1 is filter inductance in the current inner loop control subsystem, ΔI1d is d-axis perturbated current in the filter inductance L1, ΔI1q is q-axis perturbated current in the filter inductance L1,
C
i
=
1
k
i
×
k
pwm
,
ki is an integral gain of a PI controller in the current inner loop control subsystem, kpwm is gain of a converter, ΔU1d is perturbated state variable in an integral link of a d-axis PI controller in the current inner loop control subsystem, ΔU1q is perturbated state variable in an integral link of a q-axis PI controller in the current inner loop control subsystem;
the expression of the dissipation energy function is:
Vd_acc=−Rp∫ΔI1d2dt−Rp∫ΔI1q2dt,
where Vd_acc is the dissipation energy function, Rp=kp×kpwm, kp is the proportional gain of the PI controller in the current inner loop control subsystem, kpwm is the gain of the converter;
the expression of the first interaction energy function is:
Vt_dc=∫ΔIdrefΔUiddt+∫ΔIdrefΔI1ddt,
where Vt_dc is the first interaction energy function, ΔIdref is perturbated current reference value of the d-axis current inner loop generated by the DC voltage control subsystem;
the expression of the second interaction energy function is:
Vt_pll=−k1(∫ΔθpllΔUiddt+Rp∫ΔI1ddt)+k2(∫ΔθpllΔUiqdt+Rp∫ΔθpllΔI1qdt)+k3∫ΔθpllΔI1ddt+k4∫ΔθpllΔ1qdt,
where Vt_pll is the second interaction energy function, Δθpll it is perturbated phase of the phase lock loop in the phase lock loop subsystem, k1, k2, k3, and k4 are constants whose expressions are shown below:
{
k
1
=
-
I
1
⁢
q
⁢
0
k
2
=
I
1
⁢
d
⁢
0
k
3
=
-
U
pwmq
⁢
0
+
U
pccq
⁢
0
+
ω
0
⁢
L
1
⁢
I
1
⁢
d
⁢
0
k
4
=
U
pwmd
⁢
0
-
U
pccd
⁢
0
+
ω
0
⁢
L
1
⁢
I
1
⁢
q
⁢
0
,
where I1d0 is a steady-state value of d-axis current in the filter inductance L1, I1q0 is a steady-state value of q-axis current in the filter inductance L1, Upwmd0 is a steady-state value of the d-axis component of converter port voltage in the current inner loop control subsystem, Upwmq0 is a steady-state value of the q-axis component of the converter port voltage in the current inner loop control subsystem, Upccd0 is a steady-state value of d-axis voltage at a point of common coupling, Upccq0 is a steady-state value of q-axis voltage at the point of common coupling, and ω0 is rated angular frequency of the phase lock loop;
the expression of the third interaction energy function is:
Vt_q=∫ΔIqrefΔUiqdt+∫RpΔIqrefΔI1qdt,
where Vt_q is the third interaction energy function, ΔIqref is perturbated current reference value of the q-axis current inner loop generated by the reactive power outer loop control subsystem.

### Claim 14 (depends on 13)

The oscillation active damping control system for grid-tied type-4 wind turbine generator according to claim 13, wherein the small signal model of the d-axis of the current inner loop control subsystem is configured to be:
{
C
i
⁢
d
⁢
Δ
⁢
U
iq
dt
=
-
Δ
⁢
I
1
⁢
d
+
F
Cd
L
1
⁢
d
⁢
Δ
⁢
I
1
⁢
d
dt
=
-
R
p
⁢
Δ
⁢
I
1
⁢
d
+
Δ
⁢
U
id
+
F
Ld
⁢
F
Cd
=
Δ
⁢
I
dref
-
k
1
⁢
Δ
⁢
θ
pll
⁢
F
Ld
=
k
3
⁢
Δθ
+
(
Δ
⁢
I
dref
-
k
1
⁢
Δθ
pll
)
,
the small signal model of the q-axis of the current inner loop control subsystem is configured to be:
{
C
i
⁢
d
⁢
Δ
⁢
U
iq
dt
=
-
Δ
⁢
I
1
⁢
q
+
F
Cq
L
1
⁢
d
⁢
Δ
⁢
I
1
⁢
q
dt
=
-
R
p
⁢
Δ
⁢
I
1
⁢
q
+
Δ
⁢
U
iq
+
F
Lq
⁢
F
Cq
=
Δ
⁢
I
qref
-
k
2
⁢
Δ
⁢
θ
pll
⁢
F
Lq
=
k
4
⁢
Δθ
pll
+
R
p
(
Δ
⁢
I
qref
+
k
2
⁢
Δθ
pll
)
.

### Claim 15 (depends on 13)

The oscillation active damping control system for grid-tied type-4 wind turbine generator according to claim 13, wherein the energy feedback model is configured to be:
Vs_acc=Vd_acc+Vt_dc+Vt_pll+Vt_q.