Abstract: A power converter system is described. The power converter system includes a power converter comprising at least one converter unit, each converter unit comprising a plurality of semiconductor devices, each semiconductor device including at least a controllable semiconductor switch. A local controller is associated with at least one converter unit and adapted to receive CD and MD from a main controller. In response to a detected fault condition of the power converter system, the local controller is adapted to use at least one of the one or more locally-stored values to determine an operating state of the power converter system, and to use the determined operating state to select a fault operating procedure to control each associated converter unit according to the selected fault operating procedure without using any CD from the main controller.