Abstract: An electronic valve apparatus for a high voltage direct current, HVDC, power transmission system. The electronic valve apparatus includes a first device chain including a number of first devices connected in series between an input node and an output node. Each of the first devices has an asymmetric transfer function configured substantially to block current flow through the device in a first direction, and the first devices are connected such that they all block current flow in the same direction. The electronic valve apparatus also includes a second device chain including a number of second devices connected in series between the input node and the output node. Each of the second devices has an asymmetric transfer function configured substantially to block current flow through the device in a first direction, and the second devices are connected such that they all block current flow in the same direction.

Abstract: The present disclosure relates to an electronic valve apparatus for a high voltage direct current, HVDC, power transmission system. The electronic valve apparatus comprises a first device chain (301) including a plurality of first devices (302, 303) connected in series between an input node (330) and an output node (332) of the electronic valve apparatus (300, 400, 500). Each of the plurality of first devices (302, 303) has an asymmetric transfer function configured substantially to block current flow through the device in a first direction, and the plurality of first devices (302, 303) are connected such that they all block current flow in the same direction. The electronic valve apparatus also includes a second device chain (311) including a plurality of second devices (312, 313) connected in series between the input node (330) and the output node (332).

Abstract: In the field of voltage source converters for high voltage direct current (HVDC) power transmission there is provided a protection arrangement for a switching device. The protection arrangement comprises a thyristor that has main current-carrying terminals which in use are connected in reverse parallel with a switching device to be protected, whereby during normal operation of the switching device a reverse voltage is applied to the thyristor. The protection arrangement also includes a trigger circuit that is operatively connected with a gate control terminal of the thyristor. The trigger circuit is configured to apply a voltage to the gate control terminal of the thyristor when the reverse voltage applied to the thyristor reaches a safety threshold voltage whereby the thyristor fails and presents an irreversible short-circuit across the main current-carrying terminals of the switching device.

Abstract: An electrical apparatus comprises a chain-link converter which includes a plurality of chain-link sub-modules each of which is operable to provide a voltage source. The electrical apparatus also includes a switching control unit to control the chain-link sub-modules. The switching control unit is operatively interconnected with each chain-link sub-module by an electromagnetic radiation conduit. The length of the electromagnetic radiation conduit between the switching control unit and at least one chain-link sub-module differs from the length of the electromagnetic radiation conduit between the switching control unit and at least one other chain-link sub-module. The switching control unit is configured to discern a difference in the time taken for an electromagnetic signal to propagate through each different-length electromagnetic radiation conduit to thereby identify the or each chain-link sub-module associated with each different-length electromagnetic radiation conduit.

Abstract: A method of identifying a faulty sub-module of a chain-link converter is provided, wherein the chain-link converter includes a plurality of sub-modules with each sub-module including at least one switching element and an energy storage device which together are selectively operable to provide a voltage source. The method comprises the steps of: measuring a switching characteristic of each sub-module of the chain-link converter; establishing a switching characteristic signature of the chain-link converter; and identifying the or each sub-module with a switching characteristic that deviates from the switching characteristic signature as being a faulty sub-module.

Abstract: A method of identifying a faulty sub-module of a chain-link converter is provided, wherein the chain-link converter includes a plurality of sub-modules with each sub-module including at least one switching element and an energy storage device which together are selectively operable to provide a voltage source. The method comprises the steps of: measuring a switching characteristic of each sub-module of the chain-link converter; establishing a switching characteristic signature of the chain-link converter; and identifying the or each sub-module with a switching characteristic that deviates from the switching characteristic signature as being a faulty sub-module.

Abstract: An electrical apparatus comprises a chain-link converter which includes a plurality of chain-link sub-modules each of which is operable to provide a voltage source. The electrical apparatus also includes a switching control unit to control the chain-link sub-modules. The switching control unit is operatively interconnected with each chain-link sub-module by an electromagnetic radiation conduit. The length of the electromagnetic radiation conduit between the switching control unit and at least one chain-link sub-module differs from the length of the electromagnetic radiation conduit between the switching control unit and at least one other chain-link sub-module. The switching control unit is configured to discern a difference in the time taken for an electromagnetic signal to propagate through each different-length electromagnetic radiation conduit to thereby identify the or each chain-link sub-module associated with each different-length electromagnetic radiation conduit.