Method, system and storage medium for suppressing sub/super-synchronous oscillation for direct-drive wind turbine based on energy compensation

Patent metadata

Field	Value
Publication number	US-12100953-B2
Application number	US-202117372396-A
Country	US
Kind code	B2
Filing date	Jul 9, 2021
Priority date	Jul 15, 2020
Publication date	Sep 24, 2024
Grant date	Sep 24, 2024

Abstract

The disclosure relates to a method, system and storage medium for suppressing sub/super-synchronous oscillation for direct-drive wind turbine based on energy compensation. The method comprises: real-time collecting the bus voltage and the node injection current, obtaining the transient energy of direct-drive wind turbine; collecting the dynamic angle of PLL when the variation rate of the transient energy is positive, calculating the compensation energy and the increments of fundamental-frequency voltage of several supplementary energy branches based on the bus voltage and the node injection current and the dynamic angle of PLL; with the compensation energy of supplementary branches reaching the maximum and the increment of fundamental-frequency voltage being the minimum as the objective, and with the frequency-domain characteristic and fundamental-frequency voltage characteristic of control links being satisfied as the constraints, determining the compensation coefficients of supplementary energy branches, and then enabling the supplementary energy branches.

First claim

What is claimed is:

1. A method for suppressing sub-synchronous and super-synchronous oscillations for direct-drive wind turbine based on energy compensation comprising:
step S1: real-time collecting bus voltage and node injection current of the direct-drive wind turbine by a voltage transformer and a current transformer, obtaining transient energy of the direct-drive wind turbine;
step S2: collecting dynamic angle of phase locked loop (PLL) by a direct-drive wind turbine grid-side converter when variation rate of the transient energy of the direct-drive wind turbine is positive, calculating compensation energy and increments of fundamental-frequency voltage of supplementary energy branches based on the bus voltage, the node injection current of the direct-drive wind turbine, and the dynamic angle of PLL; and
step S3: determining compensation coefficients of the supplementary energy branches according to objective function and constraints, and introducing the supplementary energy branches to achieve stable operation of the wind power grid-connected system after the compensation coefficients are determined, wherein in the objective function, the compensation energy of the supplementary energy branches reaching maximum and the increment of fundamental-frequency voltage of the supplementary energy branches being, and for the constraints, frequency-domain characteristic and fundamental-frequency voltage characteristic of control links being satisfied.

2. The method for suppressing sub-synchronous and super-synchronous oscillations for direct-drive wind turbine based on energy compensation according to claim 1 , the supplementary energy branches in the step S2 comprise:
the supplementary energy branches of current loop proportional control link, current loop integral control link and dq axis cross coupling control link.

3. The method for suppressing sub-synchronous and super-synchronous oscillations for direct-drive wind turbine based on energy compensation according to claim 2 ,
wherein the supplementary energy branch of current loop proportional control link, the input term is i dc *, the proportional link with the compensation coefficient k V1 is constructed to act on the d-axis output voltage of grid-side converter control links of direct-drive wind turbine;
the compensation energy of supplementary energy branch of current loop proportional control link W V1 is
W V1 =k p2 ∫i dc *i dc dΔθ pll   (1)

where k p2 is proportion coefficient of current inner loop; i dc * is d-axis reference value of current; i dc is respectively d-axis component of current at the terminal of direct-drive wind turbine; Δθ pll represents the dynamic angle of PLL generated;
the increment of fundamental-frequency voltage of supplementary energy branch of current loop proportional control link Δu dc2 * is
Δ u dc1 *=−k p2 i dc *  (2).

4. The method for suppressing sub-synchronous and super-synchronous oscillations for direct-drive wind turbine based on energy compensation according to claim 3 , wherein the supplementary energy branch of current loop integral control link, the input term is i dc *, the integral link with the compensation coefficient k V2 is constructed to act on the d-axis output voltage of grid-side converter control links of direct-drive wind turbine;
the compensation energy of supplementary energy branch of current loop integral control link W V2 is
W V2 =k i2 ∫i dc *i dc tdΔθ pll   (3)

where k i2 is integral coefficient of current inner loop; t is the oscillation time;
the increment of fundamental-frequency voltage of supplementary energy branch of current loop integral control link Δu dc2 * is
Δ u dc2 *=−k i2 ∫i dc *dt   (4).

5. The method for suppressing sub-synchronous and super-synchronous oscillations for direct-drive wind turbine based on energy compensation according to claim 4 ,
wherein the supplementary energy branch of dq axis cross coupling control link, the input term is i dc , the proportion link with the compensation coefficient k V3 is constructed to act on the d-axis output voltage of grid-side converter control links of direct-drive wind turbine, the input term is i qc , the proportion link with the compensation coefficient k V3 is constructed to act on the q-axis output voltage of grid-side converter control links of direct-drive wind turbine;
the compensation energy of supplementary energy branch of dq axis cross coupling control link W V3 is
W V3 =ω 2 L 2 ∫( i dc 2 +i qc 2 )Δθ pll dΔθ pll   (5)

where i qc is respectively q-axis components of current at the terminal of direct-drive wind turbine; ω 2 is the angular frequency of power grid; L 2 is the reactance of outlet line;
the increment of fundamental-frequency voltage of supplementary energy branch of dq axis cross coupling control link Δu dc3 * and Δu qc3 * are:

{

Δ
⁢

⁢

u

d
⁢
c
⁢
3

*

=
0

Δ
⁢

u

q
⁢
c
⁢
3

*

=
0

.

(
6
)

6. The method for suppressing sub-synchronous and super-synchronous oscillations for direct-drive wind turbine based on energy compensation according to claim 5 , wherein the step S3,
the objective is

max
⁢

⁢
f

=



Assignees

• Univ North China Electric Power

Inventors

• Ma Jing
• Zhang Min
• Yang Zhenmiao
• Zhang Jiaming

Classifications

• H02J13/12

  Monitoring network conditions, e.g. electrical magnitudes or operational status · CPC title

• H02J3/0014 Primary

  for preventing or reducing power oscillations in networks · CPC title

• H02J2101/28

  Wind energy · CPC title

• H02J3/00142 Primary

  Oscillations concerning frequency · CPC title

• G05B2219/2619

  Wind turbines · CPC title