Abb Research Ltd.

Abb Ab

Sture Lindahl

Stefan G Johansson

Tord Bengtsson

Lars Gertmar

Udo Fromm

Marek Fulczyk

Juhani Mantere

Daniel Karlsson

Hans Christian Christensen

Gabriel Olguin

Leif-Erik Wraae

Erik Koldby Nielsen

A high voltage AC transmission cable system for transmitting power between two points, each connected to one or more power networks, and a method to operate the system. At least one transformer is arranged at each end of the AC transmission cable, wherein at least one of the transformers is arranged to operate the transformer at a voltage whereby losses due to reactive power transport and dielectric losses are minimized. The AC cable is run at a variable voltage regulated such that the voltage is a function of the load for the transmission cable. This operating voltage is not necessarily the same as the nominal voltages in the connection points. A control and communication system and a graphical user interface for carrying out the method are also provided.

System for transmission of electric power

A method for determining/dimensioning measures for restoring an electrical power system, which experiences or is heading for a voltage instability, to a steady-state condition, wherein there is no immediate risk of instability. An actual voltage/phase angle in the electrical power system is determined. The power unbalance within at least one sub-area in the electrical power system is determined. Suitable power-balancing measures are determined. The extent of the respective measures is determined. The power-balancing measures are carried out. Also, a device for carrying out the method.

Method and a device for selecting and dimensioning measures in a case of instability in an electrical power system

The present invention relates to a ground fault detection arrangement for a synchronous three-phase electrical machine, and an electrical system comprising a ground fault detection arrangement and a synchronous three-phase electrical machine. The ground fault detection arrangement injects an off-nominal frequency voltage between a neutral point of the synchronous three-phase electrical machine and ground and measure resultant currents to detect a ground fault.

Ground fault detection

A device for controlling at a fault condition. An apparatus is connected by a connection line to a grid point of a transmission net in an electric power network. A voltage raising apparatus includes a first branch connected to the grid point including a switching element and a second branch including a current resisting means. The voltage raising apparatus includes a computer for signal processing of a sensed fault condition on the network and for affecting the operation of the switching element such that on a fault condition at least part of the current is diverted through the voltage raising apparatus and for evaluation of further actions.

Electric power network

Growing community of inventors

Lund, Sweden

Sture Lindahl