Abstract:
A DC-to-DC converter assembly includes an inverter having first and second terminals connectable to a power transmission network. The inverter has a modular multilevel converter including a first inverter limb extending between the first and second terminals with first and second inverter limb portions separated by a third terminal. Each inverter limb portion includes at least one rationalized module having first and second sets of series-connected current flow control elements connected in parallel with an energy storage device. The current flow control elements include an active switching element directing current through the energy storage device and a passive current check element limiting current flow to one direction. The current flow control elements and energy storage device provide a voltage source to synthesize an AC voltage at the third terminal. A rectifier is electrically connected to the third terminal and connectable to a second power transmission network.
Abstract:
A power electronic converter for use in high voltage direct current power transmission and reactive power compensation comprises three converter limbs, each 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 a respective phase of a three-phase AC network, each converter limb defining first and second limb portions being connected in series between the respective AC terminal and a respective one of the first and second DC terminals, each limb portion including at least one switching element being controllable in use to facilitate power conversion between the AC and DC networks, the power electronic converter further including a plurality of auxiliary units, each auxiliary unit being operably associated with the respective phase of the AC network, each auxiliary unit including at least one module including a voltage source, the limb portions being controllable in use to define at least one three-phase static synchronous compensator including at least one of the plurality of auxiliary units in each branch of a star configuration, each of the first and/or second DC terminals defining the neutral point of the respective star configuration.
Abstract:
A power electronic converter, for connecting AC and DC networks and transferring power therebetween, comprises: first and second DC terminals for connection in use to a DC network; at least one primary converter limb extending between the first and second DC terminals and having first and second primary limb portions separated by a primary AC terminal for connection in use to a respective phase of a multi-phase AC network, at least one of the first and second primary limb portions including at least one primary active switching module to selectively allow current to flow through the corresponding primary converter limb in a first direction from the corresponding primary AC terminal to the DC terminals and in a second direction from the DC terminals to the corresponding primary AC terminal; and at least one secondary converter limb extending between the first and second DC terminals and having first and second secondary limb portions separated by a secondary AC terminal for connection in use to a further respective phase of the said multi-phase AC network, each of the first and second secondary limb portions including at least one passive current check element to limit current flow through the corresponding secondary converter limb to a single direction from the corresponding secondary AC terminal to the DC terminals.
Abstract:
A DC to DC converter assembly, for connecting first and second high voltage DC power transmission networks, comprising first and second modular multilevel converters, each converter including a first converter limb having first and second limb portions, each limb portion including a least one module switchable to selectively provide a voltage source and thereby vary the magnitude ratio of a DC voltage (V1, V2) across the first and second terminals of a respective converter and an AC voltage (VAC) at the third terminal of the corresponding converter, the DC to DC converter assembly further including a first link electrically connecting the third terminal of one converter, with the third terminal of the other converter, and at least one converter further including a controller configured to switch the first and second limb portions in the first converter limb of the said converter into simultaneous conduction to divert a portion (IDiV1) of current flowing within the said converter away from the first link.
Abstract:
Embedding electrical machines in gas turbine engines has particular advantages by avoiding the need to provide mechanical connections. However, electrical machines such as switched reluctance electrical machines require relatively large electrical capacitors to accommodate and filter voltage variations in the phases of the electrical machine. Generally, the electrical machine will have a motoring period or generating period with a spacer period between. By injecting electrical current as electrical power in the spacer period, there is limited effect upon net torque within the electrical machine or electrical power generation. However, such stored electrical power in an inductive winding element of the electrical machine augments power pulses provided by a power source incorporating an electrical capacitor. In such circumstances, a smaller sized electrical capacitor can be used.
Abstract:
A power electronic converter (30), for connecting AC and DC networks (46,44) and transferring power therebetween, comprises: first and second DC terminals (32,34) defining a DC link for connection to a DC network (44); wherein, in use, the DC link has a reversible DC link voltage applied thereacross; at least one converter limb (36) extending between the first and second DC terminals (32,34) and having first and second limb portions (38,40) separated by an AC terminal (42) for connection to an AC network (46), each limb portion (38,40) including at least one rationalized module (52) having first and second sets of series-connected current flow control elements (54) connected in parallel with at least one energy storage device (56), each set of current flow control elements (54) including a primary active switching element to selectively direct current through the energy storage device (56) and a primary passive current check element to limit current flow through the rationalized module (52) to a single direction, the current flow control elements (54) and the or each energy storage device (56) combining to selectively provide a voltage source to synthesize an AC voltage at the AC terminal (42); and a first controller (60) to selectively switch the or each rationalized module (52) in each limb portion (38,40) to control the configuration of the AC voltage at the corresponding AC terminal (42) so as to transfer power from the AC network (46) to the DC network (44) in an AC to DC power transfer mode and to transfer power from the DC network (44) to the AC network (46) in a DC to AC power transfer mode, wherein each limb portion (38,40) includes: one or more secondary passive current check elements (48) to limit current flow through the corresponding limb portion (38,40) to a single direction between the corresponding AC and DC terminals (42,32,34), the or each secondary passive current check element (48) being connected in series with the or each rationalized module (52); or one or more secondary active switching elements that is connected in series with the or each rationalized module (52).
Abstract:
In the field of voltage source converters which provide high voltage direct current (HVDC) power transmission and reactive power compensation there is a need for an improved power electronic module which exhibits high efficiency, provides a safe failure mode, and is tolerant of faults.A power electronic module (30; 70), for use in a chain-link converter of a voltage source converter providing high voltage direct current power transmission and reactive power compensation, comprises a first set (32) of series-connected switching elements connected in parallel with an energy storage device (34). The first set (32) of series-connected switching elements includes a first latching switching element (38) and a first non-latching switching element (40).
Abstract:
A voltage source converter for a HVDC power transmission system is disclosed. According to one aspect, the voltage source converter includes at least one phase element having series connected diodes configured to interconnect, in use, a DC network and an AC network. The voltage source converter further includes at least one auxiliary converter configured to act as a waveform synthesizer to modify the DC voltage presented to the DC side of one or more phase elements.
Abstract:
A voltage source converter for a HVDC power transmission system is disclosed. According to one aspect, the voltage source converter includes at least one phase element having series connected diodes configured to interconnect, in use, a DC network and an AC network. The voltage source converter further includes at least one auxiliary converter configured to act as a waveform synthesizer to modify the DC voltage presented to the DC side of one or more phase elements.
Abstract:
The control circuit includes first and second primary terminals for connection to a DC network, a secondary terminal connected in series between the first and second primary terminals and at least one auxiliary energy conversion element and an auxiliary terminal. The first and second primary terminals have a plurality of modules and a plurality of primary energy conversion elements connected in series therebetween to define a current transmission path, each module including at least one energy storage device, each energy storage device being selectively removable from the current transmission path. The plurality of modules include a first module and a second module the first module being connected in series with at least one primary energy conversion element between the first primary terminal and the secondary terminal to define a first current transmission path portion, and the second module being connected in series with at least one other primary energy conversion element between the second primary terminal and the secondary terminal to define a second current transmission path portion. The auxiliary energy conversion element is connected in series between the secondary and auxiliary terminals, the auxiliary terminal being for connection to ground.