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: 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: A current flow controller (10) comprising: a plurality of terminals (12a, 12b, 14a, 14b) for connection, in use, to a plurality of DC power transmission medium (16,18) such that each DC power transmission medium (16,18) is connected to at least one of the plurality of terminals (12a, 12b, 14a, 14b); and a current flow control unit interconnecting the plurality of terminals (12a, 12b, 14a, 14b), the current flow control unit including a plurality of current flow control sub-units (20, 22, 23) each of which is, in use, connected to a respective DC power transmission medium (16, 18), each current flow control sub-unit (20, 22, 23) including at least one switching element (24, 28), the or each switching element (24, 28) of each current flow control sub-unit (20, 22, 23) being connected to the same energy storage device (26; 56) to selectively provide a voltage source, and a switching control unit (100) to control switching of each switching element (24, 28) of the current flow control unit to selectively inject a

Abstract: There is a method of fault clearance for a DC power grid (10), wherein the DC power grid (10) includes: a plurality of DC terminals (12a,12b,12c,12d); a plurality of DC power transmission media (14a,14b, 14c,14d) to interconnect the plurality of DC terminals (12a, 12b, 12c, 12d); and a plurality of DC circuit interruption device stations (18), each DC circuit interruption device station (18) being associated with a respective one of the plurality of DC power transmission media (14a,14b, 14c, 14d) and a respective one of the plurality of DC terminals (12a, 12b,12c, 12d), each DC circuit interruption device station (18) including a DC circuit interruption device (20) to selectively interrupt current flow in the associated DC power transmission medium (14a, 14b, 14c, 14d), the method comprising the steps of: (i) detecting one or more faults occurring in the plurality of DC power transmission media (14a, 14b, 14c,14d); (ii) after detecting the or each fault, opening all of the DC circuit interruption devices (20)

Abstract: A multilevel voltage source converter for high voltage DC power transmission and reactive power compensation. The voltage source converter includes at least one phase element including a plurality of semiconductor switches to interconnect a DC voltage and an AC voltage. The voltage source converter also includes at least one auxiliary converter to act as a waveform synthesizer to modify the DC voltage presented to the DC side of the phase element.

Abstract: A voltage source converter is used in high voltage direct current power transmission and reactive power compensation. The voltage source converter includes first and second DC terminals for connection in use to a DC network, three phase elements and at least one auxiliary converter connected between the first and second DC terminals, each phase element including a plurality of primary switching elements and at least one AC terminal for connection in use to a respective phase of a multi-phase AC network, the plurality of primary switching elements being controllable in use to facilitate power conversion between the AC and DC networks, the or each auxiliary converter being operable in use to act as a waveform synthesizer to modify a first DC voltage presented to the DC network so as to minimize ripple in the DC voltage.

Abstract: A DC voltage source converter for use in high voltage DC power transmission comprising at least one chain-link converter connected between first and second DC terminals. The or each chain-link converter includes a chain of modules connected in series and each module including at least one pair of semiconductor switches connected in parallel with an energy storage device. The or each chain-link converter is operable when DC networks are connected to the first and second DC terminals to control switching of the modules to selectively charge or discharge the energy storage device of one or more of the modules, as required, to offset any difference in the DC voltage levels of the DC networks.

Abstract: A voltage source converter is used in high voltage direct current power transmission and reactive power compensation. The voltage source converter comprises first and second DC terminals for connection in use to a DC network, three phase elements and at least one auxiliary converter connected between the first and second DC terminals, each phase element including a plurality of primary switching elements and at least one AC terminal for connection in use to a respective phase of a multi-phase AC network, the plurality of primary switching elements being controllable in use to facilitate power conversion between the AC and DC networks, the or each auxiliary converter being operable in use to act as a waveform synthesizer to modify a first DC voltage presented to the DC network so as to minimise ripple in the DC voltage.

Abstract: A DC voltage source converter for use in high voltage DC power transmission comprising at least one chain-link converter connected between first and second DC terminals. The or each chain-link converter includes a chain of modules connected in series and each module including at least one pair of semiconductor switches connected in parallel with an energy storage device. The or each chain-link converter is operable when DC networks are connected to the first and second DC terminals to control switching of the modules to selectively charge or discharge the energy storage device of one or more of the modules, as required, to offset any difference in the DC voltage levels of the DC networks.

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 voltage source converter (10) for use in three-phase high voltage DC power transmission and reactive power compensation. The voltage source converter (10) comprises three converter limbs (12,14,16) connected in a bridge circuit arrangement wherein each of first and second converter limbs (12,14) includes a multilevel converter (18) and a third converter limb (16) includes a capacitor (20) on each side of a series AC phase connection (22). The multilevel converters (18) are controllable to synthesize waveforms at series AC phase connections (24,26) of the first and second converter limbs (12,14).

Abstract: A multilevel voltage source converter for high voltage DC power transmission and reactive power compensation. The voltage source converter includes at least one phase element including a plurality of semiconductor switches to interconnect a DC voltage and an AC voltage. The voltage source converter also includes at least one auxiliary converter to act as a waveform synthesizer to modify the DC voltage presented to the DC side of the phase element.

Abstract: An alkanoic acid ester monomer is provided having a number average molecular weight of about 1000 or less. Coalescing agents, plasticizers, and green solvents including the monomer are also provided as are methods of making the monomer. In addition, methods of coalescing components, plasticizing compositions, and dissolving solutes using the monomer are also provided.

Abstract: Polyhydroxyalkanoate compositions including hot melt adhesive compositions, biodegradable wax compositions, and protective coating compositions are provided and include a low molecular weight polyhydroxyalkanoate, a terminally-modified polyhydroxyalkanoate, or both. The compositions are biodegradable and environmentally friendly. Methods of protecting an article, such as a food product like cheese, are also provided and include coating or encapsulating the article with a composition containing a low molecular weight polyhydroxyalkanoate, a terminally-modified polyhydroxyalkanoate, or both.

Abstract: Methods of forming intermediates from PHAs are disclosed.

Abstract: An adjustable system is described for control of a genoa sheet on a sailboat. The sheet is passed through a pulley or lead block carried by a car which is slidably mounted on a track. The block and car have complementary interfitting parts to enable the block to be removed from one car and secured to another car on a second track.

Abstract: A resilient support is provided for maintaining a pivotally mounted yacht fitting in an upright position. The support is in the form of a conical section made from a resilient polymeric material.

Abstract: Water-activatible tapes are disclosed comprising a substrate of fibrous or foamed plastics material impregnated or coated with a water-reactive cementitious composition which is reactive with water to form a set mass, the composition containing at least one cement, especially Portland cement, a non-water sensitive polymeric binder, such as a natural or synthetic rubber, and a water-sensitive additive which is compatible with the polymeric binder and is sufficiently water-sensitive to at least swell in contact with water. The tapes are suitable for construction purposes, e.g. sealing joints in buildings or pipe-wrapping, by wetting with water to form a pliable mass which can be deformed to the desired shape and which will subsequently harden.