Penetration of distributed generation in the power grid is increasing. This situation leads to new possibilities but also new issues, such as anti-islanding protection. During a loss-of-mains or islanding situation, distributed generation (DG) units remain feeding a part of the electrical network without connection to the main power system. Currently, DG units have to be disconnected from the grid during islanding as soon as possible, due to potential risks for repair crews and components, poor power quality in the island and reclosing problems. A fast and reliable islanding detection method could avoid mentioned issues. Among the many existing methods, remote schemes could meet these requirements. Hence, this paper presents the operating principles of remote islanding detection methods, as well as the current state of development of communication-based remote islanding detection methods to be applied in distributed power generation systems.

Considering the importance that HVDC systems are expected to have in the future of power networks, this paper aims to provide a wide overview of the worldwide existing technologies and installations in the field of MTDC-HVDC systems. In particular, it analyses and describes both classic LCC-MTDC systems and present/future VSC-MTDC systems, the latter being based on multi-level converter technology. This way, it is expected that this paper will draw the attention of those researchers looking for a starting point, from where to be able to develop new analysis and developments that increase the applicability of future HVDC systems.

Weak power grids with DG penetration show poor power quality, protection issues and frequency deviations under severe disturbances, especially in isolated networks. This paper explores the impact of wind power in weak isolated power systems. A small size island power system has been modeled and the impact of wind power on system stability has been studied. Two main aspects have been covered: the impact on frequency stability and on transient stability, as well as fault-ride through capability of the wind turbines.