When and how to repower energy systems? A four strategies-based decision model.

Repowering systems is a long-lasting managerial endeavor where decision-makers face maintenance and optimization problems. The decision time to repower an energy system is one of the most important matters in this field. Also, in the real-world, each component of the system has different versions available in the market, so choosing the best version of components can be one of the valuable and practical issues in repowering a system. Therefore, decision-makers need optimal repowering policies in order to generate the optimal combination of system's components as well as the optimal time to repower this system with respect to important concerns such as cost, availability and safety issues. This paper provides a first-step decision-making model based on four independent repowering strategies for energy systems. A case study from offshore wind turbine system is presented afterwards to demonstrate the effectiveness of the presented policies. This decision support tool deals with the optimal repowering time and the best combination of components based on cost, availability, and safety constraints.

Wind farm topology-finding algorithm considering performance, costs, and environmental impacts.

Optimal power in wind farms turns to be a modern problem for investors and decision makers; onshore wind farms are subject to performance and economic and environmental constraints. The aim of this work is to define the best installed capacity (best topology) with maximum performance and profits and consider environmental impacts as well. In this article, we continue the work recently done on wind farm topology-finding algorithm. The proposed resolution technique is based on finding the best topology of the system that maximizes the wind farm performance (availability) under the constraints of costs and capital investments. Global warming potential of wind farm is calculated and taken into account in the results. A case study is done using data and constraints similar to those collected from wind farm constructors, managers, and maintainers. Multi-state systems (MSS), universal generating function (UGF), wind, and load charge functions are applied. An economic study was conducted to assess the wind farm investment. Net present value (NPV) and levelized cost of energy (LCOE) were calculated for best topologies found.