In the future, floating wind turbines could be used to harvest energy in deep offshore areas where higher wind mean speeds are observed. Currently, several floating turbine concepts are being designed and tested in small scale projects; in particular, one concept allows the turbine to move after installation. This article presents a novel layout optimization framework for wind farms composed of moveable floating turbines. The proposed framework uses an evolutionary optimization strategy in a nested configuration which simultaneously optimizes the anchoring locations and the wind turbine position within the mooring lines for each individual wind direction. The results show that maximum energy production is obtained when moveable wind turbines are deployed in an optimized layout. In conclusion, the framework represents a new design optimization tool for future offshore wind farms composed of moveable floating turbines.

There is a growing interest in the development of high-voltage multi-terminal direct current (MTDC) networks for integration of renewable energy sources, reinforcement of existing ac networks and feeding remote locations. Although many studies have investigated power flow control strategies for MTDC networks, few studies have looked into the possible sources of load flow errors. The aim of this paper is to analyze the effect of errors in the OPF operation of these future HVDC grids for three different sources: voltage measurement errors;variation of cable resistance with temperature and error in the prediction of the generated power from renewable sources. To perform the analysis a direct current OPF tool is used to compare two different control strategies, namely droop control and the distributed voltage control (DVC) strategy. The OPF object function is the minimization of losses in the MTDC network, which is based on the recently built 5-terminal HVDC grid in Zhoushan, China.