Method of controlling a grid side converter of a wind turbine and system suitable therefore
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
H02M-007/5387
H02M-007/539
H02J-003/38
H02P-009/00
H02M-007/483
H02P-101/15
출원번호
US-0817524
(2011-08-16)
등록번호
US-9093924
(2015-07-28)
우선권정보
DK-2010 70365 (2010-08-18)
국제출원번호
PCT/DK2011/050310
(2011-08-16)
§371/§102 date
20130612
(20130612)
국제공개번호
WO2012/022353
(2012-02-23)
발명자
/ 주소
Gupta, Amit Kumar
Anshuman, Tripathi
Cao, Shu Yu
출원인 / 주소
Vestas Wind Systems A/S
대리인 / 주소
Patterson & Sheridan, LLP
인용정보
피인용 횟수 :
1인용 특허 :
4
초록▼
According to an embodiment of the present invention, a method of controlling a grid side converter of a wind turbine is provided, wherein an output of the grid side converter is connected or connectable via a power line to an input of a grid transformer, the method comprising: determining a converte
According to an embodiment of the present invention, a method of controlling a grid side converter of a wind turbine is provided, wherein an output of the grid side converter is connected or connectable via a power line to an input of a grid transformer, the method comprising: determining a converter volt-sec occurring at the output of the grid side converter based on a converter voltage occurring at the output of the grid side converter; determining a volt-sec error between the determined converter volt-sec and a converter volt-sec reference, wherein the converter volt-sec reference is determined based on active power reference, reactive power reference, line current and a line voltage occurring at the input of the grid transformer (or at wind turbine terminals); and controlling, based on the determined volt-sec error, the grid side converter such that the volt-sec error is partly or fully compensated. The method is capable of supporting the demanded power quality even during abnormal voltage conditions, and is easy to realize. The method can seamlessly transit from linear to non-linear region of converter operation.
대표청구항▼
1. A method of controlling a grid side converter of a wind turbine, wherein an output of the grid side converter is connected or connectable via a power line to an input of a grid transformer, comprising: computing a converter volt-sec occurring at the output of the grid side converter based on a co
1. A method of controlling a grid side converter of a wind turbine, wherein an output of the grid side converter is connected or connectable via a power line to an input of a grid transformer, comprising: computing a converter volt-sec occurring at the output of the grid side converter based on a converter voltage occurring at the output of the grid side converter;determining a volt-sec error between the determined converter volt-sec and a converter volt-sec reference, wherein the converter volt-sec reference is determined based on an active power reference, a reactive power reference, a line current and a line voltage occurring at the input of the grid transformer; andcontrolling, based on the determined volt-sec error, the grid side converter such that the volt-sec error is partially or fully compensated. 2. The method according to claim 1, wherein the converter volt-sec reference is determined based on an active power volt-sec reference and a reactive power volt-sec reference. 3. The method according to claim 2, wherein the active power volt-sec reference is determined based on a difference between an active power reference demanded at the input of the grid transformer and an active power occurring at the input of the grid transformer. 4. The method according to claim 2, wherein the reactive power volt-sec reference is determined based on a difference between a reactive power reference demanded at the input of the grid transformer and a reactive power occurring at the input of the grid transformer. 5. The method according to claim 2, wherein the active power volt-sec reference and the reactive power volt-sec reference are respectively frozen if the amplitude of the line current occurring at the input of the grid transformer exceeds a predetermined threshold value. 6. The method according to claim 3, wherein the active power and the reactive power are determined based on the line current and the line voltage occurring at the input of the grid transformer. 7. The method according to claim 2, wherein determining the converter volt-sec reference comprises generating a first volt-sec reference in a dq frame in dependence on the active power volt-sec reference and the reactive power volt-sec reference. 8. The method according to claim 7, wherein the first volt-sec reference is generated as an αβ frame volt-sec vector. 9. The method according to claim 7, wherein determining the converter volt-sec reference comprises generating a second volt-sec reference by adding a grid volt-sec to the first volt-sec reference. 10. The method according to claim 9, wherein the grid volt-sec is determined based on at least one of the line current and the line voltage occurring at the input of the grid transformer. 11. The method according to claim 9, wherein determining the converter volt-sec reference comprises predicting a next sampling cycle converter volt-sec based on the second volt-sec reference, an angular velocity of the line voltage occurring at the input of the grid transformer and a sampling period of the grid side converter, and using the predicted converter volt-sec as converter volt-sec reference. 12. The method according to claim 1, wherein the controlling of the grid side converter is carried out by supplying, in dependence on the determined volt-sec error, pulse width modulation signals to the grid side converter which adjust the output voltage of the grid side converter accordingly. 13. The method according to claim 1, wherein the compensation of the volt-sec error is carried out by using a PWM switching technique in the linear region of grid side converter operation, and by using an over-modulation technique in the non-linear region of the grid side converter operation. 14. The method according to claim 1, wherein positive sequence voltages and currents are used to calculate the active power and the reactive power, or wherein negative sequence voltages and currents are used to calculate the active power and the reactive power, or wherein a combination of positive sequence voltages and currents and negative sequence voltages and currents are used to calculate the active power and the reactive power. 15. The method according to claim 1, wherein, depending on regulation and system requirements, controlling the active power to the active power reference is given priority over controlling the reactive power to the reactive power reference, or vice versa. 16. A controlling system for controlling a grid side converter of a wind turbine comprising: an inner control loop and an outer control loop;wherein the inner control loop comprises:a converter volt-sec determining unit which determines a converter volt-sec occurring at an output of a grid side converter based on a converter voltage occurring at the output of the grid side converter, wherein the output of the grid side converter is connectable via a power line to an input of a grid transformer;a volt-sec error determining unit determining a volt-sec error between the determined converter volt-sec and a converter volt-sec reference; anda controlling unit which controls, based on the determined volt-sec error, the grid side converter such that the volt-sec error is partially or fully compensated; andwherein the outer control loop is configured to determine the converter volt-sec reference based on an active power reference, a reactive power reference, a line current and a line voltage occurring at the input of the grid transformer. 17. The controlling system according to claim 16, wherein the outer control loop comprises an active power volt-sec reference determining unit and a reactive power volt-sec reference determining unit which determines an active power volt-sec reference and a reactive power volt-sec reference in a dq frame based on an active power reference and a reactive power reference requested at the input of the grid transformer. 18. The controlling system according to claim 17, wherein the active power volt-sec reference determining unit determines the active power volt-sec reference based on a difference between an active power reference and an active power occurring at the input of the grid transformer. 19. The controlling system according to claim 17, wherein the reactive power volt-sec reference determining unit determines reactive power volt-sec reference based on a difference between a reactive power reference and a reactive power occurring at the input of the grid transformer. 20. The controlling system according to claim 17, wherein the outer control loop comprises a current limiting unit which causes the active power volt-sec reference and the reactive power volt-sec reference to be respectively frozen if the amplitude of the line current occurring at the input of the grid transformer exceeds a predetermined threshold value. 21. The controlling system according to claim 16, wherein the outer control loop comprises an active power determining unit and a reactive power determining unit which determine the active power and reactive power based on the line current and the line voltage occurring at the input of the grid transformer, respectively. 22. The controlling system according to claim 17, wherein the outer control loop comprises an αβ frame volt-sec vector generating unit which generates a first volt-sec reference as an αβ frame volt-sec vector in dependence on the active power volt-sec reference, the reactive power volt-sec reference and an angle of the line voltage. 23. The controlling system according to claim 22, wherein the outer control loop comprises a second volt-sec reference generating unit which generates a second volt-sec reference by adding a grid volt-sec to the first volt-sec reference. 24. The controlling system according to claim 16, wherein the outer control loop comprises a grid volt-sec determining unit which determines the grid volt-sec based on at least one of the line current and the line voltage occurring at the input of the grid transformer. 25. The controlling system according to claim 23, wherein the outer control loop comprises a converter volt-sec reference predicting unit which predicts next sampling cycle converter volt-sec based on the second volt-sec reference, an angular velocity of the line voltage occurring at the input of the grid transformer and a sampling period of the grid side converter, and outputs the predicted converter volt-sec as converter volt-sec reference. 26. The controlling system according to claim 16, wherein the inner control loop comprises a PWM unit which controls, in dependence on the determined volt-sec error, the output voltage of the grid side converter by supplying pulse width modulation signals to the grid side converter. 27. A wind turbine, comprising: a power generator;a grid side converter, wherein the power generator is connected to the grid side converter via a generator side converter and a DC-link connecting the generator side converter with the grid side converter; anda controlling system, wherein an output of the grid side converter is connected or connectable via a power line to an input of a grid transformer, wherein the controlling system comprises an inner control loop and an outer control loop; wherein the inner control loop comprises: a converter volt-sec determining unit which determines a converter volt-sec occurring at the output of the grid side converter based on a converter voltage occurring at the output of the grid side converter;a volt-sec error determining unit determining a volt-sec error between the determined converter volt-sec and a converter volt-sec reference; anda controlling unit which controls, based on the determined volt-sec error, the grid side converter such that the volt-sec error is partially or fully compensated; andwherein the outer control loop is configured to determine the converter volt-sec reference based on an active power reference, a reactive power reference, a line current and a line voltage occurring at the input of the grid transformer.
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이 특허에 인용된 특허 (4)
Barron Benjamin (1335 143rd St. Whitestone NY 11357) Rao S. Chandrasekhara (15-47 Eberlin Dr. Fairlawn NJ 07410), Methods and apparatus for maximizing and stabilizing electric power derived from wind driven source.
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