WIND-TURBINE CONVERTER CONTROL FOR MODULAR STRING CONVERTERS

摘要

A wind turbine converter system (3) with a rectifier (4) and an inverter (5) and a converter controller (11) has at least first and second converter strings (24, 25). The converter system is controlled by a master-converter controller (13) and a slave-converter controller (12). The master-converter controller (13) controls the first converter string (25) and the slave-converter controller (12) controls the second converter string (24). The master-converter controller (13) receives commands from a superordinate wind turbine controller (21), provides the slave-converter controller (12) with string-control commands on the basis of the superordinate control commands, and controls the conversion operation of the first converter string (25) on the basis of the superordinate control command. The slave-converter controller (12) receives the string-control commands from the master-converter controller (13) and controls the conversion operation of the second converter string on the basis of the string-control commands received. The first and the second converter strings (24, 25) can be arranged in a bipolar configuration giving access to a neutral point (62). Fault detection can be performed based on the current through the neutral (62). The system is capable of fault ride-through. Also, in case of failure of the master-converter controller (13), a redundant unit takes its place.