System strength and weak grids: Fundamentals, challenges, and mitigation strategies

Abstract

© 2018 IEEE. Converter-based renewable energy sources (RES) and battery energy storage (BES) devices that are asynchronously connected to the system are becoming more and more widespread. A number of relevant stability issues, usually in areas with little synchronous generation, are being experienced, particularly in terms of voltage stability. In this context, the scope of this work is to review the key aspects of the so-called 'system strength' that is associated with 'weak grids' where such instabilities arise, its definitions, assessment metrics, and adverse operational impacts that may emerge. The paper is then discussing two main mitigation strategies to improve short-term voltage stab..