Patent ID: 8577508
Filing Date: 2013-11-05
Classification: F03D,F05B,H02M,H02P,Y02E

Abstract:
1. A method of controlling a variable-speed wind-turbine comprising: providing an AC/DC/AC PWM frequency converter comprised of a machine-side self-commutated PWM converter, a DC-link, and a grid-side self-commutated PWM converter, wherein the machine-side self-commutated PWM converter is operably connected to the wind turbine and the grid-side self-commutated PWM converter is operably connected to an electrical grid and the DC-link interconnects the machine-side self-commutated PWM converter and the grid-side self-commutated PWM converter; providing a control system operably connected to the AC/DC/AC PWM frequency converter, wherein the control system is comprised of a DC-link voltage controller and a reactive power controller; providing a q-axis control voltage, Vcq, to the control system, wherein Vcq is used by the DC-link voltage controller to control voltage of the DC-link and Vcq is determined by comparing a DC-link voltage reference value to a measured DC-link voltage value; providing a d-axis control voltage, Vcd, to the control system, wherein Vcd is used by the reactive power controller to control reactive power absorbed from the electrical grid by the grid-side self-commutated PWM converter and Vcd is determined by comparing a reactive power reference value to a measured reactive power value; and injecting, by the grid-side self-commutated PWM converter, a voltage into the electrical grid, wherein the injected voltage is less than V