Intelligent power converter control for grid integration of renewable energies

摘要

Embodiments according to the present invention provide methods and a system for a control approach that effectively maintains the DC link voltage at a constant set value under variable system conditions and keeps the converter operating with an optimal power factor range while limiting power quality effects and phase balance.

主权项

1. A method of controlling grid connection of energy sources 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 an energy source 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 nested current and voltage loop controller; providing a d-axis control current, id, to the control system; processing id to prevent harmonic disturbance to the current loop controller; comparing id to a d-axis reference current to create an id error signal; smoothing the id error signal; generating an id control current based on the id error signal, wherein the id control current is used by the nested current and voltage loop controller to control voltage of the DC-link; providing a q-axis control current, iq, to the control system; processing iq to prevent harmonic disturbance to the current-loop controller; comparing iq to a q-axis reference current to create an iq error signal; smoothing the iq error signal; and generating an iq control current based on the iq error signal, wherein the iq control current is used by the nested current and voltage loop controller to control reactive power absorbed from the electrical grid by the grid-side self-commutated PWM converter.