Back-up energy storage with in-rush current limiting for wind turbine pitch drive

Patent metadata

Field	Value
Publication number	US-9793756-B2
Application number	US-201414321662-A
Country	US
Kind code	B2
Filing date	Jul 1, 2014
Priority date	Jul 5, 2013
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

A wind turbine pitch drive system comprises an electric grid for supplying electrical power, a motor for driving a pitch actuator, an electronic converter for controlling the motor and a back-up energy storage unit for supplying electrical power. The electronic converter comprises a DC-link capacitor bank. The system furthermore comprises a switching device for selectively connecting the DC-capacitor bank link to the back-up energy storage unit, and a frequency generator for controlling the switching device. Also disclosed is a method for protecting a component of the electronic converter.

First claim

The invention claimed is:

1. A wind turbine pitch drive system comprising:
an electric grid configured to supply electrical power;
a motor configured to drive a pitch actuator;
an electronic converter configured to control the motor, the electronic converter including a DC-link capacitor bank;
a back-up energy storage unit configured to supply electrical power;
a switching device configured to selectively connect the DC-link capacitor bank to the back-up energy storage unit; and
means for protecting the electronic converter from damaging in-rushing current by controlling the in-rushing current from the back-up energy storage unit to the DC-link, wherein the in-rushing current is the current that occurs when the back-up energy storage unit is substantially charged and the DC-link to which the back-up energy storage unit is connected is substantially discharged, and energy supply is switched to the back-up energy storage unit; and
wherein the means for protecting comprises a frequency generator configured to generate a high frequency pulse based on a detected difference in voltage level between the back-up energy storage unit and the D-C link.

2. The system according to claim 1 , wherein the back-up energy storage unit comprises at least one ultra-capacitor.

3. The system according to claim 1 , wherein the back-up energy storage unit comprises at least one battery.

4. The system according to claim 1 , wherein the switching device is an insulated gate bipolar transistor.

5. The system according to claim 1 , wherein the switching device uses the high frequency pulse generated by the frequency generator to apply pulse width modulation to control the in-rushing current.

6. The system according to claim 1 , wherein the switching device uses the high frequency pulse generated by the frequency generator to apply pulse frequency modulation to control the in-rushing current.

7. A method for protecting a component of an electronic converter in a wind turbine pitch drive system that includes: an electric grid configured to supply electrical power; a motor configured to drive a pitch actuator; an electronic converter configured to control the motor, the electronic converter including a DC-link capacitor bank; a back-up energy storage unit configured to supply electrical power; a switching device configured to selectively connect the DC-link capacitor bank to the back-up energy storage unit; and a frequency generator configured to control the switching device,
the method comprising:
detecting a difference between a voltage level of the DC-link capacitor bank of the electronic converter and a voltage level of the back-up energy storage unit such that the voltage level of the back-up energy storage unit is higher than the voltage level of the DC-link capacitor bank;
generating a high frequency pulse, from the frequency generator, based on the detected difference in voltage level; and
using the high frequency pulse to intermittently switch the switching device on and off to control an in-rushing current from the back-up energy storage unit.

8. The method according to claim 7 , wherein the using of the high frequency pulse to intermittently switch the switching device comprises applying pulse modulation.

9. The method according to claim 8 , wherein the pulse modulation applied is pulse width modulation.

10. The method according to claim 8 , wherein the pulse modulation applied is pulse frequency modulation.

11. The method according to claim 7 , wherein the detecting of a difference between the voltage level of the DC-link capacitor bank of the electronic converter and the voltage level of the back-up energy storage unit comprises measuring the voltage level of the back-up energy storage unit.

12. The method according to claim 7 , wherein the detecting of a difference between the voltage level of the DC-link capacitor bank of the electronic converter and the voltage level of the back-up energy storage unit comprises measuring a voltage level at the DC-link capacitor bank.

13. The method according to claim 7 , wherein the detecting of a difference between the voltage level of the DC-link capacitor bank of the electronic converter and the voltage level of the back-up energy storage unit comprises measuring a voltage level at the electric grid.

Assignees

• Alstom Renovables Espana Sl
• Alstom Renewable Technologies

Inventors

• Palomares Rentero Pedro
• Rujas Alejandro
• Ortiz De Landazuri Héctor

Classifications

• F03D7/0224

  Adjusting blade pitch · CPC title

• F05B2260/42

  Storage of energy · CPC title

• F03D9/255

  connected to electrical distribution networks; Arrangements therefor · CPC title

• Y02E10/766

  Cross-Sectional Technologies · mapped topic

• H02J9/062

  for AC powered loads · CPC title