Picture of person typing on laptop with programming code visible on the laptop screen

World class computing and information science research at Strathclyde...

The Strathprints institutional repository is a digital archive of University of Strathclyde's Open Access research outputs. Strathprints provides access to thousands of Open Access research papers by University of Strathclyde researchers, including by researchers from the Department of Computer & Information Sciences involved in mathematically structured programming, similarity and metric search, computer security, software systems, combinatronics and digital health.

The Department also includes the iSchool Research Group, which performs leading research into socio-technical phenomena and topics such as information retrieval and information seeking behaviour.


Influence of third harmonic injection on MMC-based HVDC transmission systems

Li, Rui and Fletcher, John E. and Williams, Barry W. (2016) Influence of third harmonic injection on MMC-based HVDC transmission systems. IET Generation, Transmission and Distribution, 10 (11). pp. 5764-2770. ISSN 1751-8687

Text (Li-Fletcher-Williams-IETGTD2016-influence-of-third-harmonic-injection-on-mmc-based-hvdc)
Li_Fletcher_Williams_IETGTD2016_influence_of_third_harmonic_injection_on_mmc_based_hvdc.pdf - Accepted Author Manuscript

Download (675kB) | Preview


Whilst third harmonic injection is extensively used in modular multilevel converter (MMC) control, its significant advantages over sinusoidal modulation have not been fully explored. This paper evaluates the influence of third harmonic injection on system power losses, submodule capacitance, circulating current, and fault current and mathematical models are derived. Station conduction losses are reduced by 11%, yielding higher efficiency and lowering cooling system capacity. The submodule capacitance is reduced by 24%, which significantly lowers the capital cost, weight, and volume of the station converter. Additionally, the phase energy variation is reduced by around 18%, which benefits circulating current control. Due to the lower AC currents, the semiconductor current stresses are correspondingly reduced. In addition to the performance improvement in normal operation, the third harmonic injection reduces the DC fault currents by 13.4% and thus the fault current stresses on semiconductors and DC circuit breakers are lowered. Simulation of a point-to-point HVDC system demonstrates the effectiveness of the above analysis.