Performance assessment of special protection schemes introduced by renewable energy network integration
Presently the target of using renewable energy sources brought important challenges in the structure of Belgian electrical power network. The paper's aim is to present several studies in the protection and automation domain developed for new, more complex primary topologies to be deployed in the Belgian network. These topologies were created to cope with the increasing demand level of integration for both centralized and decentralized renewable generation and to ensure a reliable connection with HVDC VSC installations.
Flexible grids protection schemes in ELIA vision: From traditional to intelligent ones
In this moment inside the structures of electrical power grids worldwide the building of future super-grids and smart grids is starting to take shape. The utility industry, including ELIA the Belgian TSO, is facing the need to be proactive towards the challenges introduced at transmission and distribution levels by the process of massive implementation of both centralized and distributed generation. The paper's aim is to present studies in the protection and automation domain developed for new primary topologies to be deployed in the Belgian network and to cope with an increasing level of power flowing towards the transmission grid from decentralized generation installed in the distribution grid. The first study leads to the conclusion that an evolution from traditional towards flexible and adaptive protection and automation schemes is necessary in order to cope with potential system stability problems related to fault clearance time and power swing oscillations. The second study shows that the use of a flexible protection and automation scheme allows avoiding heavy investments in the primary system. The paper presents also some considerations about asset management strategy for a future deployment of these protection solutions in ELIA network.
Brushite-collagen composites for bone regeneration.
Brushite-based biomaterials are of special interest in bone regeneration due to their biocompatibility and biodegradability; on the other hand, collagen is a well-known osteoconductive biomaterial. In the present study a new brushite-collagen composite biomaterial is reported. This new biomaterial was prepared by combining citric acid/collagen type I solutions with a brushite cement powder. The obtained biomaterial was a cement paste, with improved handling properties. The effect of collagen on the setting reaction of brushite cement was studied, and was found to speed up the cement setting reaction. The cement paste set into a hard ceramic material within 18.5+/-2.1min and had compressive strength similar to that of spongeous bone (48.9+/-5.9MPa in dry conditions and 12.7+/-1.5MPa in humid conditions). The combination of collagen with citric acid revealed an interesting synergistic effect on the compressive strength of the composite material. Moreover, this new biomaterial had excellent cohesion properties (ninefold better than brushite cement), and high cellular adhesion capacity (threefold higher than brushite cement). The composite biomaterial described in this study combines good handling properties, compressive strength, cohesion and cell adhesion capacity, along with the osteoconductive and biodegradable properties inherent in brushite and in collagen-based biomaterials.