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Offshore wind integration through high voltage direct current systems

Cheah, Marc 2017. Offshore wind integration through high voltage direct current systems. PhD Thesis, Cardiff University.
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Abstract

Offshore wind generation has an important role in the transition to renewable energy. In particular, HVDC-connected Offshore Wind Power Plants (OWPPs) are emerging as an economical solution for long distances from the shore. This thesis was focused on three key areas related to planning, operation and stability issues, which are present technical challenges in the integration of OWPPs through VSC-HVDC transmission systems. In relation to planning, the installation of interlink cables between OWPPs was analysed to increase the wind power transfer. Different interlink options were compared based on a power loss reduction and an increase of availability. In general, it was recommended to have interlinks close to the wind generation point to provide more flexible active power sharing between OWPPs. Also, a cost-benefit analysis was used to quantify savings from the operation with interlinks and a design procedure was developed to determine the interlink cable capacity. In terms of operation, inertia emulation was analysed as a potential fast frequency response service from OWPPs. Synthetic inertia and temporary overproduction have been presented as main control strategies to implement inertia emulation and they were compared using MATLAB Simulink. Results showed similar frequency response performance from both strategies, however temporary overproduction was more appropriate in order to comply with system operator’s requirements. Emulation of inertia was also demonstrated in a HVDC-connected OWPP employing a hardware-in-the-loop set-up. The converter control interaction with electrical resonances of the offshore ac grid was analysed. An impedance-based representation of the system was used to identify resonant frequencies and to assess stability. A reformulation of the positive-net-damping criterion was used to evaluate the effect that the offshore HVDC converter control and OWPP configuration have on the stability. As a result, risk of resonance interaction was identified in no-load operation and when a limited number of wind turbines were connected.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Engineering
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
Uncontrolled Keywords: Offshore Wind Power Plant; High Voltage Direct Current; Voltage Source Converter; Inertia Frequency Response, Resonance Stability; Interlink Cables.
Date of First Compliant Deposit: 20 June 2017
Last Modified: 21 Aug 2019 02:24
URI: http://orca-mwe.cf.ac.uk/id/eprint/101463

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