Controlled inrush current for converter-connected grid filter

A converter arrangement for connecting a wind turbine generator with an electrical grid carrying alternating current (AC) power having one or more phases, the converter arrangement comprising:

• at least a first converter including a direct current (DC) link and configured to:
• connect with the wind turbine generator;
• and
• produce, using open-loop voltage control based on a determined voltage of the AC power, an AC output that substantially matches the AC power of the electrical grid;
• a pre-charging circuit configured to pre-charge the DC link to a predetermined voltage;
• and
• a first switching means configured to:
• enable responsive to a voltage of the DC link reaching a first threshold voltage less than the predetermined voltage, wherein enabling comprises one of charging and energizing the first switching means;
• and
• once enabled, couple the AC output of the first converter with the electrical grid after a first predetermined amount of time of operating the first converter using the open-loop voltage control.

A controller comprising:

• a computer processor configured to:
• determine a voltage of AC power carried by an electrical grid;
• operate a pre-charging circuit to pre-charge a direct current (DC) link of a converter to a predetermined voltage;
• responsive to a voltage of the DC link reaching a first threshold voltage less than the predetermined voltage, enable a switching device that is operable to connect an output of the converter with the electrical grid;
• operate, responsive to determining that the switching device is enabled and that the DC link is charged to the predetermined voltage, the converter using open-loop voltage control to produce an AC output that substantially matches the AC power of the electrical grid, the open-loop voltage control based on the determined voltage of the AC power;
• and
• operate, after a first predetermined amount of time of operating the converter using the open-loop voltage control, the switching device to couple the output of the converter with the electrical grid.