Wind turbine with parallel converters utilizing a plurality of isolated transformer windings
AssigneeGeneral Electric Company
InventorsRobert G. Wagoner, Allen M. Ritter, Anthony M. Klodowski
Life of this patent
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Abstract
A system and method are provided to isolate outputs of parallel converter threads of a power system converter of a wind turbine generator by utilizing isolated power windings on the output transformer from the converter. Such isolation eliminates the circulating common mode current between the parallel converters of the wind turbine system and eliminates the need for a common mode inductor. System reliability is enhanced and total system cost is reduced.
Claims19
A power system for providing an output power to a load, the system comprising;
- a generator configured to generate an alternating current input power to a power converter system;
- a power converter system coupled to the generator and interconnected to generate an output power and provide the output power to the load, wherein the converter system includes a plurality of parallel converter threads;
- each parallel converter thread including, in series, a semiconductor bridge ac-to-dc converter and a semiconductor bridge dc-to-ac conductor;
- a converter control system coupled to the power converter system and configured to drive the converter system to reduce harmonic components in the output power or the alternating current input power;
- and
- isolation means, for the output power from the converter to the load, comprising a single transformer, preventing common mode current circulation between the parallel converter threads as powered by voltage differences between the parallel converter threads generated by switching of power semiconductors of the semiconductor bridges of the parallel converter threads, the transformer including a plurality of sets of electrically isolated power windings between each of the converter threads and a load, wherein each set of plurality of sets of electrically isolated power windings of the transformer electrically interconnects only with an output from one corresponding parallel converter thread of the plurality of parallel converter threads and wherein the set of isolated power windings on the transformer comprises a three-phase power winding and each of the plurality of parallel converter threads comprise a three-phase power output.
A method for eliminating circulating common mode currents in a power system supplying a power output to a load from a power converter system including a plurality of parallel converter threads with each parallel converter thread including, in series a semiconductor bridge ac-to-dc converter and a semiconductor bridge dc-to-ac converter, wherein the circulating common mode currents between the parallel converter threads are powered by voltage differences between the parallel converter threads generated by switching of power semiconductors of the semiconductor bridges of the parallel converter threads, the method comprising:
- operating the generator according to a controller to three-phase ac supply power to a power converter system;
- operating the plurality of parallel converter threads to supply three-phase power to a load according to a controller for the power converter system adapted to drive the power converter system to reduce harmonic components in the power output or the alternating current input power;
- supplying the three-phase ac power from the power system converter to a load through a plurality of sets of electrically isolated three-phase power windings of a single transformer on the load side of the power system converter, wherein each set of the electrically isolated three-phase power converter thread of the plurality of parallel converter threads feeds corresponding isolated three-phase power transformer windings;
- and
- blocking the circulating common mode currents from flowing between the parallel converter threads.
A wind turbine power system adapted to prevent common mode current circulation among power system converter threads, powered by voltage differences between the parallel converter threads generated by switching of power semiconductor bridges of the parallel converter threads, when providing output power to an electrical power grid, the system comprising;
- a wind turbine generator controlled by a wind turbine controller configured to generate an alternating current input power to a power converter system;
- a power converter system coupled to the wind turbine generator and interconnected to generate an output power and provide the output power to the load, wherein the power converter system includes a plurality of the parallel converter threads;
- a converter control system coupled to the power converter system and configured to drive the parallel converter threads to reduce harmonic components in the output power or the alternating current input power;
- and
- a plurality of sets of electrically isolated power windings on a single power transformer on the output side of the converter, wherein each set of the plurality of sets of electrically isolated power windings of the transformer interconnects with only one of a corresponding parallel converter thread of the plurality of parallel converter threads, blocking circulating common mode currents from flowing between the individual converter threads.
Dependencies are inferred from the claim text.