Multi-terminal dc grid overall control with modular multilevel converters

This paper presents a control philosophy for multiterminal DC grids, which are embedded in the main AC grid. DC transmission lines maintain higher power flow at longer distances compared with AC lines. The voltage losses are also much lower. DC power transmission is good option for Russian north. Ar...

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Bibliographic Details
Published in:Journal of Mining Institute
Main Authors: Miguel Jiménez Carrizosa, Nikola Stankovic, Jean-Claude Vannier, Yaroslav E. Shklyarskiy, Aleksei I. Bardanov
Format: Article in Journal/Newspaper
Language:English
Russian
Published: Saint-Petersburg Mining University 2020
Subjects:
mmc
mt-hvdc grid
local control
dc connection
power flow calculation
voltage source inverters
droop control
hierarchical control
Mining engineering. Metallurgy
TN1-997
Arctic
Russian North
Online Access:https://doi.org/10.31897/pmi.2020.3.357
https://doaj.org/article/037623b4ecb54fb2994ad189b12fced0
Description
Summary:This paper presents a control philosophy for multiterminal DC grids, which are embedded in the main AC grid. DC transmission lines maintain higher power flow at longer distances compared with AC lines. The voltage losses are also much lower. DC power transmission is good option for Russian north. Arctic seashore regions of Russia don't have well developed electrical infrastructure therefore power line lengths are significant there. Considering above it is possible to use DC grids for supply mining enterprises in Arctic regions (offshore drilling platforms for example). Three different control layers are presented in an hierarchical way: local, primary and secondary. This whole control strategy is verified in a scaled three-nodes DC grid. In one of these nodes, a modular multilevel converter (MMC) is implemented (five sub-modules per arm). A novel model-based optimization method to control AC and circulating currents is discussed. In the remaining nodes, three-level voltage source converters (VSC) are installed. For their local controllers, a new variant for classical PI controllers are used, which allow to adapt the values of the PI parameters with respect to the measured variables. Concerning the primary control, droop control technique has been chosen. Regarding secondary level, a new power flow technique is suggested. Unbalance conditions are also verified in order to show the robustness of the whole control strategy.

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