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Multiterminal HVDC for Offshore Windfarms – Control Strategy - Paper
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| Author(s) |
Temesgen M. Haileselassie, Tore Undeland, Kjetil Uhlen |
| Abstract |
The use of HVDC for submarine power transmission is well known to increase the transmission capacity and decrease transmission losses. But so far this technology has been limited to interconnecting only two terminals as there was little or no serious demand for multi-terminal HVDC systems. With many researches going on to develop offshore wind farms in the North Sea and trends to electrify the offshore oil/gas platforms by HVDC connection from onshore, multiterminal HVDC (MTDC) could be a competitive solution for interconnecting offshore windfarms and other offshore systems into the onshore national grid. This paper discusses proposed control strategy for such a system. Voltage source converter (VSC) was selected for its suitability for MTDC system and for its flexibility in control. An equivalent circuit of the VSC in synchronous d-q reference frame has been established and decoupled control of active and reactive power was developed. A four terminal MTDC using VSCs was modeled and simulated in EMTDC/PSCAD software. A modified mix of voltage-margin-method and DC-voltaged-droop control has been used for reliable operation of the HVDC system avoiding the need for communication. Simulation results show that the proposed MTDC control system was able to maintain the DC voltage with in desired range during load switchings, step changes in power demand and was able to secure power to passive loads during loss of a DC voltage regulating converter terminal without the use of communication between terminals. |
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| Filesize: | 300.5 KB |
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| Type |
Members Only |
| Date |
Last modified 2009-12-08 by System |
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