Power conversion system and controlling method thereof and wind turbine power generation system

Patent metadata

Field	Value
Publication number	US-9866160-B2
Application number	US-201514955094-A
Country	US
Kind code	B2
Filing date	Dec 1, 2015
Priority date	Jan 4, 2015
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A system includes a source side converter for being electrically coupled to a generator of a power source, a line side converter for being electrically coupled to a power network, a DC link coupled between the source side converter and the line side converter, and a controller for generating source side switching signals based on a current or torque of the generator and a virtual impedance signal for system damping or reactive power compensation when at least one detected signal of the system is not normal. A method for controlling the system is also included.

First claim

The invention claimed is:

1. A power conversion system comprising:
a source side converter for being electrically coupled to a generator of a power source;
a line side converter for being electrically coupled to a power network;
a DC link coupled between the source side converter and the line side converter; and
a controller for generating source side switching signals for the source side converter based on a virtual impedance signal for system damping or reactive power compensation, and one of a current feedback signal of the generator or a torque feedback signal of the generator when at least one detected signal of the power conversion system is not normal.

2. The power conversion system of claim 1 , wherein the controller comprises a detection unit for receiving the at least one detected signal and generating an abnormal status signal when the at least one detected signal is not normal, and wherein the controller is programmed for generating the virtual impedance signal based on the abnormal status signal.

3. The power conversion system of claim 2 , wherein when the at least one detected signal is beyond a predetermined range or the detected signal comprises oscillations, the abnormal status signal is generated.

4. The power conversion system of claim 1 , wherein the at least one detected signal comprises a DC voltage at the DC link, a grid current, a grid voltage, or an electrical power.

5. The power conversion system of claim 1 , wherein the controller comprises a source side controller and a line side controller, and wherein the source side controller comprises:
a detection unit for receiving the detected signal and generating an abnormal status signal when the at least one detected signal is not normal;
a virtual impedance generator for generating the virtual impedance signal based on the abnormal status signal;
a regulator for generating a regulated signal based on one of a current reference or a torque reference, and one of the current feedback signal or the torque feedback signal; and
a modulator for generating the source side switching signals by comparing a control signal with at least one carrier wave, wherein the control signal comprises the virtual impedance signal, the regulated signal, or combinations thereof depending upon an existence of the abnormal status signal and a feature of the abnormal status signal.

6. The power conversion system of claim 5 , wherein the control signal comprises both the virtual impedance signal and the regulated signal during reactive power compensation.

7. The power conversion system of claim 5 , wherein the control signal comprises the virtual impedance signal and not the regulated signal during system damping.

8. The power conversion system of claim 1 , wherein the power source comprises a wind turbine, and wherein the source side converter is coupled to a rotor of the generator.

9. A method for controlling a power generation system, wherein the power generation system comprises a source side converter, a line side converter and a DC link coupled between the source side converter and the line side converter, the method comprising:
detecting at least one signal of the power generation system;
determining whether the at least one signal is abnormal; and
when any signal of the at least one signal is determined to be abnormal, generating source side switching signals for the source side converter based on a virtual impedance signal for system damping or reactive power compensation.

10. The method of claim 9 , further comprising: if any signal of the at least one signal is determined to be abnormal, generating the virtual impedance signal based on an abnormal status signal.

11. The method of claim 9 , wherein the at least one signal comprises a DC voltage at the DC link of the power generation system, a grid current, a grid voltage or an electrical power of a generator of the power generation system.

12. The method of claim 9 , wherein generating the source side switching signals comprises comparing a control signal and at least one carrier wave.

13. The method of claim 12 , further comprising: generating the control signal by a virtual impedance generator and a regulator when the reactive power compensation is provided.

14. The method of claim 12 , further comprising: generating the control signal by a virtual impedance generator when a torque or an electrical power is damped.

15. A wind turbine power generation system comprising:
a wind turbine rotor for generating mechanical power;
a generator for converting the mechanical power to electrical power;
a converter for converting the electrical power to a desired electrical power for supplying to a power network, comprising a source side converter, a line side converter, and a DC link coupled between the source side converter and the line side converter;
at least one sensor for obtaining at least one detected signal in the wind turbine power generation system; and
a controller for generating source side switching signals for the source side converter based on a virtual impedance signal for system damping or reactive power compensation, and one of a current feedback signal of the generator or a torque feedback signal of the generator when the at least one detected signal of the wind turbine power generation system is not normal.

16. The wind turbine power generation system of claim 15 , wherein the generator comprises a rotor coupled to the source side converter and a stator coupled to the power network.

17. The wind turbine power generation system of claim 15 , wherein the controller comprises a source side controller and a line side controller, and wherein the source side controller comprises:
a detection unit for receiving the at least one detected signal and generating an abnormal status signal when the at least one detected signal is not normal;
a virtual impedance generator for generating the virtual impedance signal based on the abnormal status signal;
a regulator for generating a regulated signal based on one of a current reference or a torque reference, and one of the current feedback signal or the torque feedback signal; and
a modulator for generating the converter switching signals by comparing a control signal with at least one carrier wave, wherein the control signal comprises the virtual impedance signal, the regulated signal, or combinations thereof depending upon an existence of the abnormal status signal and a feature of the abnormal status signal.

18. The wind turbine power generation system of claim 17 , wherein the control signal comprises both the virtual impedance signal and the regulated signal during reactive power compensation, and wherein the control signal comprises the virtual impedance signal and not the regulated signal during system damping.

19. The wind turbine power generation system of claim 15 , wherein the at least one detected signal comprises a DC voltage at the DC link, a grid current, a grid voltage or an electrical power.

Assignees

• Gen Electric

Inventors

• Tan Zhuohui
• Gao Jinping
• Burra Rajni Kant
• Ganireddy Govardhan

Classifications

• H02J2101/28

  Wind energy · CPC title

• H02M5/4585

  having a rectifier with controlled elements · CPC title

• H02P23/26

  Power factor control [PFC] · CPC title

• H02P9/007 Primary

  Control circuits for doubly fed generators · CPC title

• H02J3/386

  Electricity · mapped topic