Modeling and Control of DC Grids (Modellering en controle van DC netten)

The European Union's energy policy strives for a competitive, sustainable and secure energy supply. One of the most obvious results of this policy is the ongoing strong increase of renewable energy sources in the energy supply. The transmission grid updates required to accommodate this envisaged massive amount of renewable energy sources in the transmission system go well beyond standard system reinforcements used in the past: in the coming decades, a North-Sea grid interconnecting various offshore wind farms is expected to be built. This grid can gradually evolve into a European overlay supergrid connecting the offshore wind resources with the demand centers on the continent. Also solar energy, concentrated in the south of Europe, will require similar solutions. Voltage Source Converter High Voltage Direct Current (VSC HVDC) is the most suitable technological candidate to build such a grid.One of the challenges to use this technology relates to the control of the DC voltage in case of DC system contingencies, such as a converter outage. This thesis deals with the modeling and control of VSC HVDC in a meshed DC grid and multi-terminal DC systems in general. Models are developed to address both the interactions with the AC system and the control of the DC system. The main contributions of the work include a detailed comparison of different DC voltage control strategies for multi-terminal DC systems, the development of detailed dynamic and steady-state models as well as an open-source Matlab-based power flow software program, MatACDC, which enables the study of the influence of the DC voltage control on the power flows in the AC and DC systems. Furthermore, the impact of a distributed DC voltage control on the AC system transient stability is investigated, as well as the influence of the DC system layout on the DC voltage control after a contingency.

Jaar van publicatie:2013

Toegankelijkheid:Open