Abstract: A control circuit (20) comprising: first and second terminals (22,24) for respective connection to first and second power transmission lines (26,28); a current transmission path extending between the first and second terminals (22,24) and having first and second current transmission path portions (30,32) separated by a third terminal (34), either or both of the first and second current transmission path portions (30,32) including at least one module (36), the or each module (36) including at least one energy storage device; an auxiliary terminal (42) for connection to ground or the second power transmission line (28); an energy conversion block for removing energy from the power transmission lines (26,28), the energy conversion block extending between the third and auxiliary terminals (34,42) such that the energy conversion block branches from the current transmission path, the energy conversion block including at least one energy conversion element (44); and a control unit (46) which selectively removes the

Abstract: There is a control circuit comprising first and second DC terminals for connection to a DC network, the first and second DC terminals having a plurality of modules and at least one energy conversion element connected in series therebetween to define a current transmission path, the plurality of modules defining a chain-link converter, each module including at least one energy storage device, the or each energy storage device being selectively removable from the current transmission path to cause a current waveform to flow from the DC network through the current transmission path and the or each energy conversion element and thereby remove energy from the DC network, the or each energy storage device being selectively removable from the current transmission path to modulate the current waveform to maintain a zero net change in energy level of the chain-link converter.

Abstract: A power electronic converter for use in high voltage direct current power transmission and reactive power compensation which includes at least one converter limb including first and second DC terminals for connection in use to a DC network. The or each converter limb includes at least one first converter block and at least one second converter block connected between the first and second DC terminals. The or each first converter block includes a plurality of line-commutated thyristors and at least one first AC terminal for connection in use to an AC network. The or each second converter block includes at least one auxiliary converter including a plurality of self-commutated switching elements. The self-commutated switching elements are controllable in use to inject a voltage to modify a DC voltage presented to the DC side of the converter limb and/or modify an AC voltage and an AC current on the AC side of the power electronic converter.

Abstract: The control circuit includes first and second primary terminals for connection to a DC network, a secondary terminal connected in series between the first and second primary terminals and at least one auxiliary energy conversion element and an auxiliary terminal. The first and second primary terminals have a plurality of modules and a plurality of primary energy conversion elements connected in series therebetween to define a current transmission path, each module including at least one energy storage device, each energy storage device being selectively removable from the current transmission path.

Abstract: In the field of voltage source converters which provide high voltage direct current (HVDC) power transmission and reactive power compensation there is a need for an improved power electronic module which exhibits high efficiency, provides a safe failure mode, and is tolerant of faults. A power electronic module (30; 70), for use in a chain-link converter of a voltage source converter providing high voltage direct current power transmission and reactive power compensation, comprises a first set (32) of series-connected switching elements connected in parallel with an energy storage device (34). The first set (32) of series-connected switching elements includes a first latching switching element (38) and a first non-latching switching element (40).

Abstract: A voltage source converter for a HVDC power transmission system is disclosed. According to one aspect, the voltage source converter includes at least one phase element having series connected diodes configured to interconnect, in use, a DC network and an AC network. The voltage source converter further includes at least one auxiliary converter configured to act as a waveform synthesizer to modify the DC voltage presented to the DC side of one or more phase elements.

Abstract: A power electronic converter for use in high voltage direct current power transmission and reactive power compensation which comprises at least one converter limb including first and second DC terminals for connection in use to a DC network, the or each converter limb including at least one first converter block, and at least one second converter block connected between the first and second DC terminals; the or each first converter block including a plurality of line-commutated thyristors and at least one first AC terminal for connection in use to an AC network, the or each second converter block including, at least one auxiliary converter including a plurality of self-commutated switching elements; wherein the self-commutated switching elements are controllable in use to inject a voltage to modify a DC voltage presented to the DC side of the converter limb and/or modify an AC voltage and an AC current on the AC side of the power electronic converter.

Abstract: A power electronic converter for use in high voltage direct current power transmission and reactive power compensation comprises a plurality of switching elements interconnecting in use a DC network and one or more AC networks, the plurality of switching elements being controllable in use to facilitate power conversion between the AC and DC networks, wherein in use, the plurality of switching elements are controllable to form one or more short circuits within the power electronic converter so as to define one or more primary current flow paths, the or each primary current flow path including a respective one of the AC networks and the power electronic converter and bypassing the DC network.

Abstract: A voltage source converter for high voltage DC power transmission is disclosed. According to one aspect, the voltage source converter is connectable between a DC network and another electrical network to interconnect the DC network and the other electrical network. The voltage source converter includes a converter unit configured to convert power flowing between the DC network and the other electrical network and at least one fault unit. One or more of the fault units includes at least one fault module having a voltage source that is operable, in the event of a short circuit in a DC network connected to the voltage source converter, to produce a voltage that acts to reduce current flowing through the voltage source converter and the short circuit.

Abstract: A circuit for a hybrid voltage source converter suitable for high voltage DC power transmission and reactive power compensation. The circuit comprises an assembly of electrically interconnected elements (Elements 1 to 20) including a plurality of first elements (Elements 1 to 6) and a plurality of second elements (Elements 7 to 20). Each of the first and second elements is configurable to be bypassed, to be disconnected or to include a circuit arrangement of one or more electronic components to construct, in use, a hybrid voltage source converter including at least one first element and at least one second element and in which the circuit arrangement included in the or each first element is different to the circuit arrangement included in the or each second element.