Abstract: An electrical field shielding assembly comprises at least one electrically conductive, shielding element (12) that is hingably mounted on the electrical field shielding assembly, wherein the or each shielding element (12) is hingably movable between an open position in which an access opening in the electrical field shielding assembly is created and a closed position in which the access opening in the electrical field shielding assembly is closed.

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 semiconductor switching circuit includes a main current branch which includes at least one main semiconductor switching element and through which current flows in a first direction when the or each main semiconductor switching element is switched on. The semiconductor switching circuit also includes an auxiliary current branch that is connected in parallel with the main current branch. The auxiliary current branch includes at least one auxiliary semiconductor switching element. One or more control units are configured to switch on the or each auxiliary semiconductor switching element as the or each main semiconductor switching element is switched on to selectively create an alternative current path via the auxiliary current branch whereby current flowing in the first direction through the main current branch is diverted instead to flow through the alternative current path to reduce the rate of change of current flowing through the or each main semiconductor switching element.

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.

Abstract: A semiconductor switching string includes a plurality of series-connected semiconductor switching assemblies, each having a main semiconductor switching element that includes first and second connection terminals. The main semiconductor switching element also has an auxiliary semiconductor switching element electrically connected between the first and second connection terminals. Each semiconductor switching assembly also includes a control unit configured to switch on a respective auxiliary semiconductor switching element to selectively create an alternative current path between the first and second connection terminals whereby current is diverted to flow through the alternative current path to reduce the voltage across the corresponding main semiconductor switching element.

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

Abstract: A current limiter for selectively limiting a rate of change of current in a DC electrical network may include a first electrical block including an inductive element and a second electrical block including a bidirectional switch. The first electrical block is connected in parallel with the second electrical block between first and second terminals, and the first and second terminals are connectable to the DC electrical network. The bidirectional switch is switchable to: (1) a first mode to permit current flow through the second electrical block in a first current direction and at the same time inhibit current flow through the second electrical block in a second, opposite current direction; and (2) a second mode to permit current flow through the second electrical block in the second current direction and at the same time inhibit current flow through the second electrical block in the first current direction.

Abstract: A circuit interruption device includes a main branch; a secondary branch having an electrical on-resistance which is higher than an electrical on-resistance of the main branch; and first and second terminals for connection to an electrical network, the main and secondary branches extending between the first and second terminals. The main branch includes a switching apparatus which is switchable to selectively allow current to flow in the main branch in a normal mode of operation or commutate current from the main branch to the secondary branch in a fault mode of operation. The secondary branch includes a switching device, the switching device including a normally-on switching element. The secondary branch further includes a control unit in communication with the normally-on switching element. The secondary branch further includes a power extraction circuit which is electrically coupled with the control unit.

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 control circuit (20) comprises: first and second terminals (22,24) for respective connection to first and second power transmission lines (26,28); a current transmission path (30,32) extending between the first and second terminals (22,24), the current transmission path (30,32) including at least one module (36), the or each module (36) including at least one energy storage device, the current transmission path (30,32) including at least one inductor (38); a control unit (46) which selectively removes the or each energy storage device of the or each module from the current transmission path (30,32) to modulate a voltage across the or each inductor (38) in a filtering mode to modify current flowing through the current transmission path (30,32) and thereby filter one or more current components from the power transmission lines (26,28); and at least one energy conversion element, wherein the control unit (46) selectively removes the or each energy storage device of the or each module (36) from the current tran

Abstract: An electrical apparatus (10) comprises: first and second terminals (18,20) for connection to an electrical circuit; a chain-link converter (22) connected between the first and second terminals (18,20), the chain-link converter (22) including a plurality of chain-link modules (24), each chain-link module (24) inluding at least one switching element (26) and at least one energy storage device (28), the or each switching element (26) and the or each energy storage device (28) of each chain-link module (24) combining to selectively provide a voltage source; and a protection device (32) connected across an electrical block (34) that includes at least two of the plurality of chain-link modules (24), the protection device (32) including a plurality of series-connected semiconductor devices (36), wherein the protection device (32) selectively provides a current-conductive path to allow at least part of a current flowing in the electrical apparatus (10) to bypass the electrical block (34).

Abstract: An extinguishing branch (28) for an electrical circuit (32) includes: a snubber circuit (36) including an energy storage limb (40), wherein the energy storage limb (40) includes first and second energy storage limb portions separated by a first junction (46) to define a first voltage divider, and each energy storage limb portion includes at least one energy storage device (48,50); and an arrester limb (38) connected across the energy storage limb (40), wherein the arrester limb (38) includes first and second arrester limb portions separated by a second junction (52) to define a second voltage divider, and each arrester limb portion includes at least one arrester element (54,56), wherein the first and second junctions (46,52) are connected to define a voltage divider bridge, and the voltage divider bridge is electrically coupleable to the electrical circuit (32) so as to provide, in use, a driving voltage to drive the electrical circuit (32).

Abstract: A switching device (28) comprising a primary switching block (30) including at least one semiconductor switch (34); and a switching control unit (32) to control the switching of the or each semiconductor switch (34). The switching device further includes a crowbar circuit (46) comprising a crowbar switch (56) switchable to selectively allow current to flow through the crowbar switch (56) in order to bypass the or each switching module; and a secondary switching block including a switching element (58) connected across a control electrode and a cathode of the crowbar switch (56). The switching element (58) is in communication with the switching control unit (32) to receive, in use, a control signal (66) generated by the switching control unit (32) when the primary switching block (30) is operating within predefined operating parameters.

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 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 circuit breaker for high voltage direct current (HVDC) power transmission includes a module with a pair of terminals for connection to an electrical network, and four of conduction paths. Each first conduction path includes a mechanical switch connected in series with at least one first semiconductor switch to selectively allow current to flow between the first and second terminals through the first conduction path in a first mode of operation or commutate current from the first conduction path to the second conduction path in a second mode of operation. The second conduction path also has a semiconductor switch to selectively allow current to flow between the terminals through the second conduction path or commutate current from the second conduction path to the third conduction path in the second mode of operation.

Abstract: A circuit breaker apparatus for use in high voltage direct current (HVDC) power transmission is provided. The circuit breaker apparatus has one module or a plurality of series-connected modules, the or each module including: first, second, third and fourth conduction paths and first and second terminals for connection to an electrical network, each conduction path extending between the first and second terminals, the first conduction path including a mechanical switching element, the second conduction path including at least one semiconductor switching element, the third conduction path including a snubber circuit having an energy storage device and the fourth conduction path including a resistive element.

Abstract: A circuit breaker apparatus (32) comprises one module (30) or a plurality of series-connected modules (30), the or each module (30) including: first and second conduction paths (34, 36); and first and second terminals (38, 40) for connection to an electrical network (42), each conduction path (34, 36) extending between the first and second terminals (38, 40); the first conduction path (34) including a first vacuum switching element (52) to selectively close to allow current to flow between the first and second terminals (38, 40) through the first conduction path (34) in a first mode of operation, or open to block current from flowing between the first and second terminals (38, 40) through the first conduction path (34) in a second mode of operation; the second conduction path (36) including a second vacuum switching element (56) to selectively open to block current from flowing between the first and second terminals (38, 40) through the second conduction path (36) in the first mode of operation, or close to a

Abstract: An electrical field shielding assembly comprises at least one electrically conductive, shielding element (12) that is hingably mounted on the electrical field shielding assembly, wherein the or each shielding element (12) is hingably movable between an open position in which an access opening in the electrical field shielding assembly is created and a closed position in which the access opening in the electrical field shielding assembly is closed.