Hvdc converter comprising fullbridge cells for handling a DC side short circuit

Abstract

A power electronic converter (40) for use in high voltage direct current power transmission and reactive power compensation comprises three converter limbs (42), each converter limb (42) including first and second DC terminals (46,48) for connection in use to a DC network (52) and an AC terminal (50) for connection in use to a respective phase of a three- phase AC network (54), each converter limb (42) defining first and second limb portions (56,58) being connected in series between the respective AC terminal (60) and a respective one of the first and second DC terminals (46,48), each limb portion (56,58) including at least one switching element (62,66) being controllable in use to facilitate power conversion between the AC and DC networks (52,54), the power electronic converter (40) further including a plurality of auxiliary units (44), each auxiliary unit (44); being operably associated with the respective phase of the AC network (54), each auxiliary unit (44) including at least one module (60) including a voltage source, the limb portions (56,58) being controllable in use to define at least one three-phase static synchronous compensator including at least one of the plurality of auxiliary units (44) in each branch of a star configuration, each of the first and / or second DC terminals (46,48) defining the neutral point of the respective star configuration.

Description

technical field [0001] The present invention relates to a power electronic converter for high voltage direct current (HVDC) power transmission and reactive power compensation. Background technique [0002] In power transmission networks, alternating current (AC) power is typically converted to direct current (DC) power for transmission via overhead lines and / or submarine cables. This conversion removes the need to compensate for the effect of AC capacitive loading imposed by the transmission line or cable, and thereby reduces the cost per kilometer of wire and / or cable. Therefore, the conversion from AC to DC becomes cost-effective when electricity needs to be transmitted over long distances. [0003] Conversion from AC power to DC power is also used in power transmission networks where it is necessary to interconnect AC networks operating at different frequencies. [0004] In any such power transmission network, every interface between AC and DC power requires a converter...

AI Technical Summary

Problems solved by technology

However, non-zero DC flowing in a voltage source converter results in persistent arc formation when the contacts are opened using conventional mechanical circuits

Therefore, an expensive, dedicated DC circuit disconnecting device must be used to interrupt the DC side fault current, which results in an increase in converter size, weight and cost

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