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In HVDC converters that employ a line-commutated control, reactive power is absorbed by the rectifier and inverter terminals during AC/DC conversion. An AC filter usually consists of filters and large shunt capacitors to supply reactive power to the HVDC station. When STATCOM is used to supply reactive power to the HVDC system with AC filter, the low-order harmonics generated from STATCOM can result in a resonance between the shunt capacitor and AC network. Therefore, a control strategy based on selective harmonic elimination is adopted to minimize the low-order harmonics from STATCOM. The cancellation of harmonic instabilities is verified through simulations in PSCAD/EMTDC.

This paper deals with a new concept for calculating DC harmonic voltages and currents of line- commutated HVDC systems. In contrast to the conventional method, this method is useful for BTB (Back-To-Back) HVDC systems without smoothing reactors or PTP (Point-To-Point) with very short transmission line. This method proposes a new direction for HVDC system design and analysis. The proposed method is applied to a 50 Hz/60 Hz BTB test system and a synchronized BTB test system. After simulation and verification, the new results are introduced.

The paper deals with the cost evaluation concerning the implementation of a 2000MW HVDC link over a 200km distance. Two different dc voltages have been considered, namely +/−300kVdc and 500kVdc. Two different scheme configurations have been considered, namely a single bipole system and a double bipole system.