Abstract: A direct current breaker for a high voltage direct current application includes: two high voltage electron tubes arranged in an anti-parallel connection, and a control circuit for receiving, from a control system, infrared pulses including control information, the control circuit further including a device configured to convert the infrared pulses into electrical control signals, for controlling a switching status of the direct current breaker. An electrical power system includes such direct current breaker.

Abstract: A direct current breaker for a high voltage direct current application includes: two high voltage electron tubes arranged in an anti-parallel connection, and a control circuit for receiving, from a control system, infrared pulses including control information, the control circuit further including a device configured to convert the infrared pulses into electrical control signals, for controlling a switching status of the direct current breaker. An electrical power system includes such direct current breaker.

Abstract: An interface arrangement for connection between an AC system and a DC system and to a method of disconnecting a DC system from an AC system are disclosed. The arrangement includes a converter for conversion between AC and DC having a DC side for connection to the DC system and an AC side for being coupled to the AC system, a set of circuit breakers coupled between the AC side of the converter and the AC system and a breaker assisting unit including a set of branches connected between the AC side of the converter and ground, where each branch includes a switch in series with an impedance element.

Abstract: An interface arrangement is provided for coupling between an AC system and a DC system. The arrangement includes a converter for conversion between AC and DC and having a DC side and an AC side, a transformer having a primary side with primary windings for coupling to the AC system and a secondary side with secondary windings coupled to the converter, where the secondary windings are coupled to ground via a neutral point of the secondary side, and a filter with filter elements set for removing a frequency component of at three times the fundamental frequency of an AC voltage appearing on the AC side of the converter. The filter is connected between the neutral point of the secondary side of the transformer and ground.

Abstract: An interface arrangement for connection between an AC system and a DC system and to a method of disconnecting a DC system from an AC system are disclosed. The arrangement includes a converter for conversion between AC and DC having a DC side for connection to the DC system and an AC side for being coupled to the AC system, a set of circuit breakers coupled between the AC side of the converter and the AC system and a breaker assisting unit including a set of branches connected between the AC side of the converter and ground, where each branch includes a switch in series with an impedance element.