Converter device and method for converting electrical power

摘要

A converter device (for power conversion in e.g. a power plant such as a wind turbine is disclosed. An individual controller is provided for each phase of an electrical output power of the converter. If a voltage of one phase is indicated as being out of a predetermined voltage band, an active current of this phase is set to zero and optionally a reactive component of this phase is set to a value that depends on the indicated voltage.

主权项

1. A converter device for converting an input power to an electrical output power having at least two phases, the converter device comprising:
a voltage input for receiving a voltage signal for each of said at least two phases, said voltage signal being indicative of a voltage of the respective phase of the electrical output power; an individual controller for each of said at least two phases, each controller sets an active current to zero when the voltage of the respective phase is outside a predetermined voltage band; a frequency converter is provided for each phase in order to effect the setting of the active current to zero, the frequency converter comprises an input for receiving the input power and an output for outputting the respective phase of the output power, wherein a reactive component of the electrical output power is set for each phase separately depending on the voltage signal for this phase under consideration, wherein the reactive component is a reactive current, wherein each individual controller includes a control input for receiving a control signal from a power plant controller, wherein the individual controller controls, based on the control signal, the respective frequency converter, wherein the predetermined voltage band is preprogrammed in the individual controller or the predetermined voltage band is set with the individual controller after receiving the control signal from the power plant controller, wherein at least one of said individual controllers implements a predetermined change of reactive component per voltage unit of a change in the voltage indicated by the voltage signal, said predetermined change of reactive component per voltage unit defining a reactive component gradient, and wherein said at least one controller controls the reactive component of its phase according to an in-band reactive component gradient if the voltage indicated by the voltage signal is inside the predetermined voltage band and for controlling the reactive component of its phase according to an out-of-band reactive component gradient if the voltage indicated by the voltage signal is outside the predetermined voltage band.