Optimal control of offshore wind farm collector systems during outages

Harvesting the full potential of inter-array cabling

Master thesis (2023)

Authors

M.J. Ubbens Mechanical Engineering

Contributors

B.H.K. De Schutter Delft Center for Systems and Control (supervisor 1)
A. Haghani Vattenfall (supervisor 1)
S. Grammatico Delft Center for Systems and Control (supervisor 2)
H. Polinder Transport Engineering and Logistics - Mechanical, Maritime and Materials Engineering (supervisor 2)
Faculty
Mechanical Engineering
Copyright: © 2023 Martiene Ubbens
Model predictive control Offshore wind farm Cable outages Optimization-based control Dynamic thermal rating
More Info
expand_more

Published Date

29-06-2023

Language

English

Reuse Rights

Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.

Faculty

Mechanical Engineering

Abstract

Ambitions to limit climate change are incentivizing the expansion of renewable energy. In particular, offshore wind energy is expected to grow rapidly. To harness the full potential of existing as well as prospected offshore wind farms, the limited capacity of the internal cable network of the offshore wind farm, called the collector system, should be efficiently used.

The operation of the collector system during cable outages presents significant potential in this regard. Currently, during these outages, a conservative approach is taken that under-utilizes the capacity of the collector system and consequently limits power production excessively. The available headroom of the system can be unlocked by optimizing the power routing and turbine setpoints. This optimization problem is the topic of the MSc Thesis, carried out
within Vattenfall.

Two novel optimization-based rerouting and setpoint decision frameworks are developed for collector systems with arbitrary topologies: an open-loop control strategy and a receding horizon control strategy.

The open-loop control strategy assumes that the network can only be reconfigured at the beginning of the outage. It is formulated as a mixed-integer linear programming problem, in which the cables are modeled as binary control variables and the setpoints as continuous control variables.

The receding horizon control strategy is deployed in real time, leveraging cable temperature measurements and power forecasts to derive optimal control actions dynamically. Dynamic thermal rating is applied, which entails that the power flows are constrained based on the cables’ temperatures rather than on a static rating. The resulting control strategy is formulated as a mixed-integer quadratically constrained programming problem.

A case study is performed to compare the performance of the developed strategies to existing strategies. Simulations concerning seven occurred cable outages at an offshore wind farm show an average increase in power production with respect to the industry control strategy of 0.82% for the open-loop control strategy and 4.2% for the receding horizon control strategy.