An apparatus includes a mechanical switch and a solid-state switch, such as a diamond switch or antiparallel-connected thyristor pair, coupled in series between an AC source and the load, such as a substation input transformer. The control circuit may be configured to connect the AC power source to the load by closing the mechanical switch and turning on the solid-state switch thereafter. The control circuit may be configured to interrupt a connection of the AC source to the load by turning off the solid-state switch and closing the mechanical switch thereafter. Operations of the switches may be coordinated with a fuse coupled in series with the solid-state switch to address different types of fault conditions.

An apparatus includes a mechanical switch and a solid-state switch, such as a diamond switch or antiparallel-connected thyristor pair, coupled in series between an AC source and the load, such as a substation input transformer. The control circuit may be configured to connect the AC power source to the load by closing the mechanical switch and turning on the solid-state switch thereafter. The control circuit may be configured to interrupt a connection of the AC source to the load by turning off the solid-state switch and closing the mechanical switch thereafter. Operations of the switches may be coordinated with a fuse coupled in series with the solid-state switch to address different types of fault conditions.

A control system controls a plurality of controllable units with a central control device and further has a plurality of control modules, each of which is assigned to one of the units to be controlled. The central control device is set up to exchange digital data with each control module. The control modules form a connection network, wherein each control module is connected to at least one other control module via a communication line so that data exchange between them is possible. One of the control modules is directly connected to the central control device as the master node of the connection network, and the control modules are set up to form a communication network within the connection network, so that the data exchange between the central control device and each control module can be respectively carried out via an assigned communication path within the communication network.

A control system controls a plurality of controllable units with a central control device and further has a plurality of control modules, each of which is assigned to one of the units to be controlled. The central control device is set up to exchange digital data with each control module. The control modules form a connection network, wherein each control module is connected to at least one other control module via a communication line so that data exchange between them is possible. One of the control modules is directly connected to the central control device as the master node of the connection network, and the control modules are set up to form a communication network within the connection network, so that the data exchange between the central control device and each control module can be respectively carried out via an assigned communication path within the communication network.

A thyristor starter is configured to accelerate a synchronous machine from a stop state to a predetermined rotation speed by sequentially performing a first mode of performing commutation of an inverter by intermittently setting DC output current of a converter to zero and a second mode of performing commutation of the inverter by induced voltage of the synchronous machine. The thyristor starter is further configured to raise induced voltage in proportion to the rotation speed of the synchronous machine by keeping field current constant and to suppress rise of the induced voltage by reducing the field current after the induced voltage reaches a first voltage value, in the first mode.

A thyristor starter is configured to accelerate a synchronous machine from a stop state to a predetermined rotation speed by sequentially performing a first mode of performing commutation of an inverter by intermittently setting DC output current of a converter to zero and a second mode of performing commutation of the inverter by induced voltage of the synchronous machine. The thyristor starter is further configured to raise induced voltage in proportion to the rotation speed of the synchronous machine by keeping field current constant and to suppress rise of the induced voltage by reducing the field current after the induced voltage reaches a first voltage value, in the first mode.

Provided is a method of controlling a multi-channel multi-phase electrical machine including a plurality of channels each with a set of phase windings connected to a converter, which method includes the steps of operating the converters to electrically phase-shift the channels; computing harmonic injection currents for a dominant harmonic on the basis of electrical quantities in a rotating reference frame; determining harmonic voltage references for the dominant harmonic on the basis of the harmonic injection currents; and regulating the AC output voltages of the channels according to the fundamental voltage references and the harmonic voltage references. Also provided is a control arrangement of a multi-channel multi-phase electrical machine; a wind turbine; and a computer program product.

The invention provides an inverter system and a method of using said inverter system. A rectifier stage of the inverter system is used to charge a DC link stage to a first voltage level and a control module determines whether voltages over series connected capacitors of the DC link stage are balanced. If those voltages are balanced, the rectifier stage charges the DC link stage to a second voltage level higher than the first voltage level.

This application provides a solid-state transformer and a bus voltage equalization method for a solid-state transformer. The solid-state transformer may include a plurality of cascaded modules and a bus voltage equalization module. Input terminals of all the cascaded modules are connected in series, and output terminals of all the cascaded modules are connected in parallel, and are used as a parallel output terminal of the solid-state transformer. The bus voltage equalization module is connected in parallel to the parallel output terminal of the solid-state transformer. Each cascaded module may include a bus capacitor (for example, all capacitors connected in series to each other on a direct current bus.

An apparatus includes a mechanical switch and a solid-state switch, such as a diamond switch or antiparallel-connected thyristor pair, coupled in series between an AC source and the load, such as a substation input transformer. The control circuit may be configured to connect the AC power source to the load by closing the mechanical switch and turning on the solid-state switch thereafter. The control circuit may be configured to interrupt a connection of the AC source to the load by turning off the solid-state switch and closing the mechanical switch thereafter. Operations of the switches may be coordinated with a fuse coupled in series with the solid-state switch to address different types of fault conditions.