Abb Technology Ag

Asea Aktiebolag

Asea Brown Boveri Ab

Abb Technology Ltd

Allmanna Svenska Elektriska Aktiebolaget

Abb Schweiz Ag

Abb Ab

Asea Ab

Lars-Erik Lennart Juhlin

Bertil Berggren

Per-Erik Bjorklund

Tomas Jonsson

Kerstin Linden

Lidong Zhang

Gunnar Flisberg

Ulf Radbrant

Jurgen Häfner

Per Holmberg

Gunnar Asplund

Ying Jiang-Häfner

Kjell Eriksson

Ake Ekstrom

Gote Liss

A device for damping of high frequency currents is provided. The device includes a conductor extending along a main axis, a first damping path including a first damping element extending along a first axis and a second damping path including a second damping element extending along a second axis. The first and second damping elements are arranged on opposite sides of the conductor. The main axis, the first axis and the second axis are different and separate from each other. The first damping element and the second damping element are spaced apart from the conductor and electrically connected in parallel with the conductor between a first position and a second position along the conductor. Further, from the first position to the second position, a resistance of the conductor is lower than a resistance of either one of the first and second damping paths.

Device for high frequency current damping

A DC grid () comprising a plurality of AC/DC converters () which are interconnected via DC lines () is provided, wherein, in order to limit the effects of a fault in the DC grid, the DC grid is divided into at least two zones () by means of at least one current limiter () in a manner so that a current limiter is connected in each of the DC line(s) () by which two zones are interconnected. A method of limiting the effects of a fault in a DC grid by dividing the DC grid into at least two zones is also provided.

DC grid and a method of limiting the effects of a fault in a DC grid

A voltage balancing unit for a symmetric monopole high voltage direct current (HVDC) transmission line interconnecting two voltage source converters (VSCs), the transmission line including first arresters having a first switching impulse protective level (SIPL) is provided. The voltage balancing unit includes a pair of second arresters having a second SIPL which is less than the first SIPL, and a switching device being arranged for temporarily connecting, in the event of a voltage unbalance on the transmission line, the first arresters between either pole and ground. A voltage unbalance on the transmission line may be removed by temporarily connecting second arresters, with a significantly lower SIPL than the first arresters, for limiting the pole voltage to a level close to the normal voltage. Further, a method of voltage balancing is provided. Voltage unbalances may arise as a consequence of lightning induced earth faults.

Voltage balancing of symmetric HVDC monopole transmission lines after earth faults

A high voltage direct current (HVDC) switchyard is provided. The switchyard is arranged for interconnecting three or more sections of an HVDC power network, such as transmission lines, converters, or any other type of HVDC equipment. The switchyard comprises at least one main circuit breaker and at least four transfer switches. The at least one main circuit breaker and the at least four transfer switches are arranged so as to enable to individually disconnect any one of the at least three sections of the HVDC power distribution network. In an embodiment of the invention, the transfer switches which usually are comprised in direct current (DC) hybrid circuit breakers are used as selector switches, thereby reducing the number of main breakers in the switchyard.

Using the transfer switch of a hybrid circuit breaker as selector switch

The present invention relates to a fault detection system for detection of line faults on an electrode line in an HVDC system wherein the electrode line comprises a first and second branch connected in parallel. The fault detection system comprises a first and second pulse generation circuit arranged to generate electrical pulses onto the first and second branches, respectively, as well as first and second current measurement devices arranged to generate signals indicative of electrical signals occurring in first and second injection lines, respectively. The possibility of independent generation of electrical pulses onto the first and second branches, respectively, as well as the independent registration of first and second signal patterns representing electrical signals on the first and second injection lines, respectively, increases the information content in the collected data, thereby facilitating for a more reliable analysis of whether or not a fault is present on the electrode line.

Line fault detector

A breaker failure detection device for a direct current (DC) circuit breaker () is provided. The circuit breaker comprises a circuit breaking element () and a non-linear resistor, e.g., a surge arrester (), connected in parallel. The breaker failure detection device comprises a current sensor (), for measuring a current commutating from the circuit breaking element (), and a breaker failure detection unit (). The breaker failure detection unit () is arranged for comparing the measured current to desired values and deciding that an internal commutation process of the circuit breaker () does not proceed as desired if the measured current deviates from the desired values. The present invention makes use of an understanding that an improved detection of breaker failures may be achieved by monitoring the internal commutation process of the circuit breaker. Further, a method of breaker failure detection is provided.

Fast breaker failure detection for HVDC circuit breakers

A method is provided for controlling power flow within a wind park system for power transmission to a main power grid, the wind park system including two or more parallel-connected island wind park grids. The method includes the steps of: controlling a first voltage source converter as a swing bus in frequency control, the frequency control including controlling frequency to a steady state reference operating point for operating points within a power dead band and by frequency droop control when exceeding an end point of the power dead band, and controlling at least a second voltage source converter in power control, the power control including controlling power flow to a steady state reference operating point for operating points within a frequency dead band and by power droop control when exceeding an end point of the frequency dead band. A controller and computer program product are also provided.

Method for controlling power flow within a wind park system, controller, computer program and computer program products

The invention relates to an HVDC breaker () comprising at least two individually controllable HVDC breaker sections () connected in series, wherein the HVDC breaker is arranged in a manner so that the number of HVDC breaker sections tripped upon tripping of the HVDC breaker depends on the operational event in response to which the tripping occurs. The invention further relates to a control apparatus () for controlling the HVDC breaker, as well as to a method of breaking an HVDC line. The method comprises receiving () a system status signal indicative of an operational event requiring the breaking of the HVDC line, and determining () the number of HVDC breaker sections required for the breaking.

HVDC breaker and control apparatus for controlling an HVDC breaker

A meshed HVDC power transmission network comprises at least three HVDC converter stations interconnected in a first closed path by at least three transmission lines. A first DC power flow control device is series connected to a first of the at least three transmission lines. That first DC power flow control device takes its power from the first transmission line and balances the DC current distribution in the first closed path.

Power flow control in a meshed HVDC power transmission network

A current-limitation system for limiting a current through an DC connection in case of a fault occurring in a DC grid of which the DC connection forms a part is provided, as well as a method of operating a current-limitation system for limiting a current through an DC connection in case of a fault occurring in a DC grid of which the DC connection forms a part.

Current limitation system for limiting the effects of a fault in a DC grid and a method of operating a current limitation system

A method for controlling power flow within a multi-terminal DC power transmission system including two or more converter stations and the corresponding multi-terminal DC power transmission system are provided. The method includes the steps of: controlling the power flow to a steady state reference operating point for operating points within a control dead band defined for each respective converter station, and controlling the power flow by means of droop control in at least one of the converter stations upon detection of exceeding of an end point of one or more of the control dead bands.

Multi-terminal DC transmission system and method and means for control there-of

In a multi-terminal HVDC power transmission network comprising at least three HVDC converter stations interconnected by at least two transmission lines, where at least one of the transmission lines is a long line, an active voltage source device is series connected to one of the transmission lines, which maintains the DC voltage of the transmission lines of the network to be within a predefined voltage range by injecting an additional DC voltage in series with the one transmission line.

DC voltage compensation in a multi-terminal HVDC power transmission network

A high voltage AC/DC or DC/AC power conversion system including a voltage source converter with at least two series-connected converter valve bridges, at least two reactors, where each of the reactors is connected to one of the AC phase terminals of the at least two bridges and at least one transformer connected to an AC supply voltage. In order to block a DC voltage from the at least one transformer, one of at least two capacitors is connected in series with each of the at least two reactors and is connected between the corresponding reactor and the at least one transformer.

Voltage source converter for high voltage direct current power transmission

A method and a device to compensate for an asymmetrical DC bias current in a multi-phase transformer. The transformer is connected between an AC power system and an AC/DC or DC/AC high voltage converter. For each phase of the AC side of the transformer a current quantity is determined. The current quantity reflects the time dependent behavior of the magnetizing current in the phase. Time intervals in the current quantity are determined during which the current quantity reaches a positive or a negative maximum, respectively. A DC magnetizing quantity is determined from a difference between the amplitude of the positive maximum and the amplitude of the negative maximum. An asymmetrical quantity is determined from a difference between the amplitudes of the positive and/or negative maxima of at least two of the phases and a control signal is generated from the asymmetrical quantity and provided to a control device of the converter in order to adjust the generation of the AC or DC voltage in the particular phase of the converter which corresponds to the phase of the AC side of the transformer.

Method and device to compensate for an asymmetrical DC bias current in a power transformer connected to a high voltage converter

A converter station for connecting an AC system to a bipolar HVDC transmission line. A DC neutral arrangement includes first DC breakers enabling breaking of a first current path from the neutral bus of one pole to the neutral bus of the other pole at bipolar operation of the station for changing to monopolar operation thereof for isolation of a faulty section of the system while establishing a current path to electrode line connecting members for diverting the current from the one pole thereto. A separate connecting member is provided for each of the electrode lines. A connector is configured to connect each neutral bus to an optional of the two electrode line connecting members.

Growing community of inventors

Ludvika, Sweden

Lars-Erik Lennart Juhlin