Medium voltage inverter to establish grid interface and provide ancillary support for a DC distributed wind farm

More utility companies now require wind power plants to participate in grid support functions including frequency, voltage and inertia support. Typical wind turbine generator configurations cannot provide grid support. In this paper, a multi-level inverter based wind turbine power conversion system is investigated. The developed inverter interfaces between the DC bus of a wind turbine power conversion system supported by energy storage elements and the grid. Two control techniques are proposed for capacitor-based and battery-based storage systems to provide grid active and reactive power support. Details of control implementation for grid interface, frequency and voltage droop support are presented. Simulation and experimental results are discussed to verify the viability of the proposed system and control techniques.