Analysis, Tuning of Controllers and Interconnection of a Battery Energy Storage System for Subsynchronous Resonance Mitigation in Wind Farms.

Abstract

Wind generation is the most promising green power for bulk production and, according to the Global Wind Energy Council (GWEC), each generation of wind turbines becomes more cost-e cient. Based on GWEC, wind energy conversion systems (WECS) is the best solution for contributing to climate change. Although this is a promising solution, this technology brings troubles associated with its topology. The most remarkable issue occurs because usually, the location of WECS is far away from the consumption facility, as it is well reported. For any investment, the location of these wind farms requires thorough planning. At the same time, environmental awareness questions the construction of additional overhead transmission lines. In this context, series-compensated transmission lines are an excellent solution since enabling more power to be transmitted through existing lines at a fraction of the cost and time expenditure of a new line. However, series-compensated transmission lines are prone to subsynchronous oscillations originated by subsynchronous resonance. This is a relatively new phenomenon due to that the rst time it was observed in a WECS was in 2003. Considering the context, this Thesis addresses the problem of subsynchronous reso- nance in series compensated transmission lines using as a benchmark a DFIG-based wind farm for study case. The aim of this research work is to analyze thoroughly the reasons that provoke the subsynchronous resonance, putting special focus on its consequences in DFIG-based wind farms. Also, to explore possible solutions for mitigating this problem, the incorporation of a battery energy storage system is included and analyzed using math- ematical tools to determine its in uence to improve the reliability of the whole system. As a result, a methodology for tuning the controllers of the back-to-back converter of the DFIG-based wind farm is performed. Mathematical tools used in power systems are used to identify the modes related to the subsynchronous resonance, also a mathematical approach is proposed to understand the causes that produce subsynchronous resonance. A discrimination and identi cation process for subsynchronous resonance is proposed. Finally, the integration of a battery energy storage system is studied as a possible scheme that contributes to improving the facility performance when it lies in a subsynchronous resonance condition; for that purpose, two schemes for the battery energy storage system are analyzed to the subsynchronous resonance mitigation.