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 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 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 method for reversing accounting distortions of financial information, comprising the steps of obtaining a set of financial information regarding an entity, the financial information including accounting distortions and notes detailing said accounting distortions; analyzing the financial information and notes to determine an accurate economic model; and using said accurate economic model to automatically determine the true profitability of an entity and comparatively value a plurality of expectations with respect to the financial information.
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 voltage source converter for use in high voltage DC power transmission and reactive power compensation. The voltage source converter comprises at least one converter limb including first and second DC terminals for connection in use to a DC network and an AC terminal for connection in use to an AC network.The or each converter limb defines first and second limb portions, each limb portion including at least one switching element connected in series with a chain-link converter between a respective one of the first and second DC terminals and the AC terminal. The switching elements of the first and second limb portions is operable to switch the respective chain-link converters in and out of circuit between the respective DC terminal and the AC terminal. The chain-link converters are operable to generate a voltage waveform at the AC terminal.
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 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:
A voltage source converter comprising three phase elements defining a star connection in which a first end of each phase element is connected to a common junction; at least two converter limbs, each converter limb including first and second DC terminals for connection in use to a DC network and an AC terminal connected in series with a second end of a phase element, each converter limb defining first and second limb portions, including a chain-link converter, each chain-link converter including chain-link modules; and a third DC terminal connected to the common junction of the star connection to define an auxiliary connection, wherein in use a current is injected into the auxiliary connection to modify a voltage of each chain-link module in each limb portion.
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.