Abstract: This application relates to methods and apparatus for control apparatus of a voltage source converter for direct current transmission of electrical power over a transmission line. The control apparatus comprises regulation control for generating a regulation signal for the converter to regulate an electrical parameter of the voltage source converter, such as voltage or power, so as to regulate power transmission over the transmission line. The regulation signal is based on the difference between a measured value of said parameter and a reference value of said parameter, as may be supplied from a reference control block and may be derived from a demand signal indicating the voltage or power demand. The apparatus also includes damping control configured to generate a damping signal for modulating said regulation signal to reduce the effect of resonance within the bandwidth of control of the converter.

Abstract: This application relates to control methods and apparatus for a voltage source converter comprising a plurality of energy storage devices which can be selectively connected into an arm of the voltage source converter. The apparatus is configured to generate a modelled value of the voltage of an energy storage device of the voltage source converter based on one or more model parameters and the operation of the voltage source converter, receive the modelled value and also a measured value of the voltage of at least one energy storage device, determine an error between the modelled value and the measured value, and generate a model control signal for adapting the model based on said error so that the modelled value substantially corresponds to the measured value. Control circuitry is responsive to said model module and/or said model adaptation module to control operation of the voltage source converter.

Abstract: A voltage source converter (30) comprises a converter limb (36), having primary and secondary limbs connected in parallel between first and second DC terminals (32,34), the primary limb element including first and second primary limb element portions (38,40) separated by a third terminal (42), being connectable to an AC electrical network (46), each primary limb element portion (38,40) including at least one primary switching element (50), the secondary limb including first and second secondary limb element portions (52,54) separated by a junction (56), and including a DC side chain-link converter (58), and a connection interconnecting the third terminal (42) and the junction (56) wherein the voltage source converter (30) further includes a control unit (62) controlling the switching of the respective switching elements.

Abstract: A voltage source converter, for interconnecting electrical networks, comprises a converter structure which includes a terminal for connection to the first electrical network and a terminal for connection to the second electrical network. The converter structure also includes at least one module that is connected between the terminals. The module includes at least one energy storage device and at least one switching element. The energy storage element and switching element are operable to selectively provide a voltage source. The converter structure still further includes an integrated passive fault current limiter that is configured to present a first impedance to a normal current flowing in the voltage source converter during normal operation of the voltage source converter, and is configured to present a second impedance to a fault current flowing in the voltage source converter during a fault condition. The first impedance is lower than the second impedance.

Abstract: A voltage source converter includes a converter limb having limb portions separated by an AC terminal and extending between DC terminals, each limb portion including a primary switching element to switch the limb portion into and out of circuit. The converter further includes an auxiliary limb. The primary switching element of each limb portion is switchable to switch the auxiliary limb into and out of circuit with the corresponding limb portion. The converter further includes a control unit to, in one mode, inject a circulation current that flows in one direction in one of the limb portions and minimize a current flowing in the opposite direction in that limb portion. Each primary switching element switches the respective limb portion into or out of circuit following the minimization of the limb portion current by the circulation current.

Abstract: This application relates to control methods and apparatus for a voltage source converter comprising a plurality of energy storage devices which can be selectively connected into an arm of the voltage source converter. The apparatus is configured to generate a modelled value of the voltage of an energy storage device of the voltage source converter based on one or more model parameters and the operation of the voltage source converter, receive the modelled value and also a measured value of the voltage of at least one energy storage device, determine an error between the modelled value and the measured value, and generate a model control signal for adapting the model based on said error so that the modelled value substantially corresponds to the measured value. Control circuitry is responsive to said model module and/or said model adaptation module to control operation of the voltage source converter.

Abstract: This application relates to methods and apparatus for control apparatus of a voltage source converter (401) for direct current transmission of electrical power over a transmission line (402). The control apparatus comprises regulation control (403) for generating a regulation signal for the converter to regulate an electrical parameter of the voltage source converter, such as voltage or power, so as to regulate power transmission over the transmission line. The regulation signal is based on the difference between a measured value of said parameter and a reference value of said parameter, as may be supplied from a reference control block (404) and may be derived from a demand signal indicating the voltage or power demand. The apparatus also includes damping control (405) configured to generate a damping signal for modulating said regulation signal to reduce the effect of resonance within the bandwidth of control of the converter.

Abstract: A voltage source converter includes a converter limb having limb portions separated by an AC terminal and extending between DC terminals, each limb portion including a primary switching element to switch the limb portion into and out of circuit. The converter further includes an auxiliary limb. The primary switching element of each limb portion is switchable to switch the auxiliary limb into and out of circuit with the corresponding limb portion. The converter further includes a control unit to, in one mode, inject a circulation current that flows in one direction in one of the limb portions and minimize a current flowing in the opposite direction in that limb portion. Each primary switching element switches the respective limb portion into or out of circuit following the minimization of the limb portion current by the circulation current.

Abstract: A voltage source converter (30) comprises a converter limb (36), having primary and secondary limbs connected in parallel between first and second DC terminals (32,34), the primary limb element including first and second primary limb element portions (38,40) separated by a third terminal (42), being connectable to an AC electrical network (46), each primary limb element portion (38,40) including at least one primary switching element (50), the secondary limb including first and second secondary limb element portions (52,54) separated by a junction (56), and including a DC side chain-link converter (58), and a connection interconnecting the third terminal (42) and the junction (56) wherein the voltage source converter (30) further includes a control unit (62) controlling the switching of the respective switching elements.

Abstract: A voltage source converter comprises: at least two converter limbs, each converter limb extending between DC terminals and having limb portions separated by an AC terminal. Each limb portion includes at least one switching element and at least one chain-link converter including series-connected modules. Each module includes at least one switching element and at least one energy storage device that combine to selectively provide a voltage source. The chain-link converter(s) form a branch to interconnect two AC terminals. Each limb portion is switchable to switch the corresponding chain-link converter(s) into and out of circuit with a respective DC terminal. The chain-link converter(s) is switchable to control the configuration of an AC voltage at each corresponding AC terminal. The converter further includes a control unit that coordinates the switching of the limb portions and the chain-link converter(s) to cause transfer of real power between the AC and DC electrical networks.

Abstract: A voltage source converter includes a converter limb extending between DC terminals and having limb portions separated by an AC terminal, the DC terminals being connectable to a DC electrical network and the AC terminal being connectable to an AC electrical network. Each limb portion includes at least one switching element and a chain-link converter including a series-connected modules, each module including at least one switching element and at least one energy storage device combining to selectively provide a voltage source. The chain-link converter is connected to the AC terminal, and the switching element(s) of each limb portion is switchable to switch the chain-link converter into and out of circuit with the corresponding DC terminal. The voltage source includes a control unit which coordinates the switching of the switching elements of the limb portions and the switching element(s) in each module of the chain-link converter.

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 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.