A distributed and fault-tolerant control system for a new modular wind turbine converter

Distributed control solutions are being pursued for new modular converter topologies. In this paper, a novel distributed control system is presented for a modular wind turbine drive with 12 parallel converter modules, where each module has a local control platform and two central control units are used, one active and one redundant unit. A comparison is done of ring versus star network topologies, and it is concluded that the star topology has the advantages of lower latency, higher bandwidth, and better synchronization and the drawbacks of a complex central controller and lower scalability. Analysis is done for fault-tolerant, synchronized operation with a redundant star network topology using 100BASE-TX Ethernet for communications. Furthermore, small custom Ethernet data packets transmitted at regular intervals are used which provides benefits of ensured data integrity, low signal latency, and simple synchronization. Experimental results demonstrate ca. 20 ns synchronization precision, and interruption-free fault tolerance.