Multilink DC Transmission for Offshore Wind Power Integration
Author
Craciun, Bogdan-Ionut
Term
4. term
Education
Publication year
2011
Submitted on
2011-05-30
Abstract
Dette speciale adresserer integrationen af offshore vindkraft i elnettet ved hjælp af VSC-baseret HVDC i en flerterminal (MTDC) konfiguration. Udgangspunktet er den hurtige vækst i vindenergi og de tilhørende udfordringer med langdistance transmission, systemstabilitet og overholdelse af TSO-krav, hvor HVAC er begrænset offshore. Specialet fokuserer på deling af aktiv effekt mellem konvertere i et MTDC-system ved brug af droop-regulering koblet med virtuel impedans. Metodisk udvikles en detaljeret MTDC-model i PSCAD/EMTDC, og der etableres en kontrolstruktur for VSC’erne (strømregulering, DC-spændingskontrol, aktiv effektsstyring og PLL). Modellen vurderes gennem simulationsstudier, der omfatter effektrin, betydningen af delingsfaktoren, indflydelsen af virtuel modstand samt hændelser som vindfarm-udkobling, modtagestations-udkobling og linjeparametermismatch. Dernæst foretages laboratorievalidering på en 15 kW VSC-platform for at sammenholde simulation og praksis og belyse systemets respons og effektdelingsadfærd under forskellige driftsforhold. Resultater præsenteres som simulations- og eksperimentelle observationer, og arbejdet afrundes med konklusioner og forslag til fremtidigt arbejde.
This thesis addresses the integration of offshore wind power into the grid using VSC-based HVDC in a multi-terminal (MTDC) configuration. Motivated by the rapid growth of wind energy and the challenges of long-distance transmission, system stability, and compliance with TSO requirements—where HVAC faces offshore limitations—the work focuses on sharing active power among converters in an MTDC system via droop control combined with virtual impedance. The methodology develops a detailed MTDC model in PSCAD/EMTDC and a control structure for the VSCs (current control, DC voltage control, active power control, and PLL). The model is evaluated through simulation studies covering power steps, the influence of the sharing factor, the effect of virtual resistance, and events such as wind farm trips, receiving station trips, and line parameter mismatch. Laboratory validation is then performed on a 15 kW VSC platform to compare simulations with practice and to illustrate system response and active power sharing behavior under varying operating conditions. Results are presented as simulation and experimental observations, followed by conclusions and suggestions for future work.
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