Abstract: A circuit interruption device including first and second terminals for connection, to a respective electrical circuit or network, a current-conductive branch including first, second, and third current-conductive branch portions successively connected in series between the first and second terminals, the first current-conductive branch portion including a first switching element, the second current-conductive branch portion including a second switching element, the third current-conductive branch portion including a third switching element, each switching element configured to be switchable to selectively permit and block a flow of current in the respective current-conductive branch portion, first and second current bypass paths, the first current bypass path connected across the first and second current-conductive branch portions, the second current bypass path connected across the second and third current-conductive branch portions, and a controller configured to selectively control the switching of the swit

Abstract: A circuit interruption device including first and second terminals for connection, to a respective electrical circuit or network, a current-conductive branch including first, second, and third current-conductive branch portions successively connected in series between the first and second terminals, the first current-conductive branch portion including a first switching element, the second current-conductive branch portion including a second switching element, the third current-conductive branch portion including a third switching element, each switching element configured to be switchable to selectively permit and block a flow of current in the respective current-conductive branch portion, first and second current bypass paths, the first current bypass path connected across the first and second current-conductive branch portions, the second current bypass path connected across the second and third current-conductive branch portions, and a controller configured to selectively control the switching of the swit

Abstract: The present invention provides an efficient and cost-effective process to recover highly purified PHA homopolymers and copolymers, producing novel sequestered amorphous polyhydroxyalkanoate polymer (SAPP) materials derived from cellular biomass that are crystal competent. Such resulting materials (e.g., melt-derived solids and crystalline agglomerates), as well as methods of production of the sequestered amorphous polyhydroxyalkanoate polymer (SAPP) materials and subsequent processing, demonstrate cost-effective production of PHA polymer at commercial scale, which is heretofore not been achievable. Moreover, the methods and materials produced make feasible the long-awaited achievement in the industry for competitive commercialization of PHA homopolymers and copolymers from cellular biomass.

Abstract: The present invention provides an efficient and cost-effective process to recover highly purified PHA homopolymers and copolymers, producing novel sequestered amorphous polyhydroxyalkanoate polymer (SAPP) materials derived from cellular biomass that are crystal competent. Such resulting materials (e.g., melt-derived solids and crystalline agglomerates), as well as methods of production of the sequestered amorphous polyhydroxyalkanoate polymer (SAPP) materials and subsequent processing, demonstrate cost-effective production of PHA polymer at commercial scale, which is heretofore not been achievable. Moreover, the methods and materials produced make feasible the long-awaited achievement in the industry for competitive commercialization of PHA homopolymers and copolymers from cellular biomass.

Abstract: In the field of high voltage direct current (HVDC) power transmission there is provided a power converter assembly (10) comprising a line-commutated power converter (12) that is configured to transfer power from a DC network (14) to a corresponding receiving AC network (16). The power converter assembly (10) also includes a control unit which is operatively associated with the line-commutated power converter (12) and is programmed, in response to the receiving AC network (16) exhibiting a reduced AC voltage (Va, Vb, Vc), to cause a reduction in the operating DC voltage (VDC) of the line-commutated power converter (12) by the DC network (14).

Abstract: A method and apparatus for controlling a fault blocking voltage source converter apparatus which is, in use, connected to an AC system and a DC system for power transmission, in the event of a DC side interruption operating the voltage source converter apparatus after identification of a need for a DC side interruption based on a voltage order, so as to extract at least some electrical energy stored in the connected DC system to the voltage source converter apparatus.

Abstract: In the field of high voltage direct current (HVDC) power transmission there is provided a power converter assembly (10) comprising a line-commutated power converter (12) that is configured to transfer power from a DC network (14) to a corresponding receiving AC network (16). The power converter assembly (10) also includes a control unit which is operatively associated with the line-commutated power converter (12) and is programmed, in response to the receiving AC network (16) exhibiting a reduced AC voltage (Va, Vb, Vc), to cause a reduction in the operating DC voltage (VDC) of the line-commutated power converter (12) by the DC network (14).

Abstract: A method and apparatus for start-up of a voltage source converter (VSC) which is connected to an energized DC link (DC+, DC?). The VSC is connected to a first AC network via a first transformer and an AC isolation switch, the AC isolation switch being coupled between the first transformer and the AC network. The method involves using an auxiliary AC power supply to generate an AC supply to energize the first transformer with the AC isolation switch open. The VSC is then started, with a VSC controller using the AC supply generated by the auxiliary AC power supply as a reference for controlling the VSC. The auxiliary AC power supply may also be used to supply power to at least one VSC load, such as the controller and/or an auxiliary load such as a cooling system. Once the VSC is started the isolation switch 204 can be closed.

Abstract: A converter apparatus and methods of operation thereof are disclosed. In an example, a converter unit of a bipole converter apparatus comprising a neutral connection having a breaker switch is disclosed. In the event of a DC fault, the fault condition may be monitored and it is determined whether a breaker switch operation condition is met. The breaker switch is opened when the breaker switch operation condition is met. In one example, the breaker switch operation condition may comprise a current level.

Abstract: An electrical assembly includes a power converter having first and second DC terminals which are connectable to a DC electrical network. The power converter also includes converter limbs connected between the first and second DC terminals. Each converter limb includes an AC terminal that is connectable to a respective AC phase of a multi-phase AC electrical network. Each converter limb also includes limb portions, each connected between a corresponding AC terminal and a respective one of the first and second DC terminals. Each limb portion includes switching element(s). The electrical assembly includes a single grounding circuit having a reactor configured to provide a current path for alternating current with a high impedance to ground and a current path for direct current with a low impedance to ground. The grounding circuit is arranged so that only one of the AC phases is connected to ground via the grounding circuit.

Abstract: An electrical assembly includes a power converter having first and second DC terminals which are connectable to a DC electrical network. The power converter also includes converter limbs connected between the first and second DC terminals. Each converter limb includes an AC terminal that is connectable to a respective AC phase of a multi-phase AC electrical network. Each converter limb also includes limb portions, each connected between a corresponding AC terminal and a respective one of the first and second DC terminals. Each limb portion includes switching element(s). The electrical assembly includes a single grounding circuit having a reactor configured to provide a current path for alternating current with a high impedance to ground and a current path for direct current with a low impedance to ground. The grounding circuit is arranged so that only one of the AC phases is connected to ground via the grounding circuit.

Abstract: A converter includes first and second DC terminals for connection to a DC network, limb(s) connected between the first and second DC terminals, and a controller. Each limb includes a phase element and DC side sub-converter(s). The phase element has switching elements and AC terminal(s) for connection to an AC network, the switching elements being switchable to selectively interconnect a DC side voltage at a DC side of the phase element and an AC side voltage at an AC side of the phase element, The DC side sub-converter(s) connected to the DC side of the phase element. The controller selectively controls the switching elements and the operation of each DC side sub-converter as a voltage synthesiser. The controller also controls the switching elements to provide a blocking voltage to limit or block the flow of a fault current between the AC and DC networks and through each limb.

Abstract: A converter apparatus and methods of operation thereof are disclosed. In an example, a converter unit of a bipole converter apparatus comprising a neutral connection having a breaker switch is disclosed. In the event of a DC fault, the fault condition may be monitored and it is determined whether a breaker switch operation condition is met. The breaker switch is opened when the breaker switch operation condition is met. In one example, the breaker switch operation condition may comprise a current level.

Abstract: This application relates to a voltage source converter, especially for use in High Voltage Direct Current power distribution/transmission, and to methods of control of such a voltage source converter. The voltage source converter has at least one phase limb having a high-side DC terminal, a low-side DC terminal and an AC terminal. In embodiments of the invention each phase limb comprises a voltage wave-shaper operable, in use, to provide a selectively variable voltage level. Each phase limb also has a switch arrangement operable to provide at least first and second switch states. In the first switch state the low-side DC terminal is electrically connected to the AC terminal via a first path that includes the voltage wave-shaper. In the second switch state the high-side DC terminal is electrically connected to the AC terminal via a second path that includes the voltage wave-shaper.

Abstract: A method and apparatus for controlling a fault blocking voltage source converter apparatus which is, in use, connected to an AC system and a DC system for power transmission, in the event of a DC side interruption operating the voltage source converter apparatus after identification of a need for a DC side interruption based on a voltage order, so as to extract at least some electrical energy stored in the connected DC system to the voltage source converter apparatus.

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: A method and apparatus for start-up of a voltage source converter (VSC) which is connected to an energized DC link (DC+, DC?). The VSC is connected to a first AC network via a first transformer and an AC isolation switch, the AC isolation switch being coupled between the first transformer and the AC network. The method involves using an auxiliary AC power supply to generate an AC supply to energize the first transformer with the AC isolation switch open. The VSC is then started, with a VSC controller using the AC supply generated by the auxiliary AC power supply as a reference for controlling the VSC. The auxiliary AC power supply may also be used to supply power to at least one VSC load, such as the controller and/or an auxiliary load such as a cooling system. Once the VSC is started the isolation switch 204 can be closed.

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) including 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 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: 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)