Back-up energy storage with in-rush current limiting for wind turbine pitch drive
AssigneeALSTOM Renewable Technologies
InventorsPedro Palomares Rentero, Alejandro Rujas, Héctor Ortiz De Landazuri
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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.
Claims13
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.
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.
Dependencies are inferred from the claim text.