Multidisciplinary design optimization of large wind turbines—Technical, economic, and design challenges

Abstract

a b s t r a c tWind energy has experienced a continuous cost reduction in the last decades. A popular cost reduction technique is to increase the rated power of the wind turbine by making it larger. However, it is not clear whether further upscaling of the existing wind turbines beyond the 5-7 MW range is technically feasible and economically attractive. To address this question, this study uses 5, 10, and 20 MW wind turbines that are developed using multidisciplinary design optimization as upscaling data points. These wind turbines are upwind, 3-bladed, pitch-regulated, variable-speed machines with a tubular tower. Based on the design data and properties of these wind turbines, scaling trends such as loading, mass, and cost are developed. These trends are used to study the technical and economical aspects of upscaling and its impact on the design and cost. The results of this research show the technical feasibility of the existing wind turbines up to 20 MW, but the design of such an upscaled machine is cost prohibitive. Mass increase of the rotor is identified as a main design challenge to overcome. The results of this research support the development of alternative lightweight materials and design concepts such as a two-bladed downwind design for upscaling to remain a cost effective solution for future wind turbines.

A Research Framework for the Multidisciplinary Design and Optimization of Wind Turbines

“…The first allows to maximize the AEP of the rotor, while the second minimizes the loads produced by the blades. Another formulation at system-level has been presented by Ashuri et al [21,22]. Here, a preliminary round of design can be made by optimizing blade length, tower height, and the rotor speed for minimum COE.…”

A Metric Space with LCOE Isolines for Research Guidance in wind and hydrokinetic energy systems

“…This option also increases the metric M2 by reducing the material factors f t of the components (j = 1,2, … n), which are part of the equivalent mass of the turbine -see also equation (13). This option also increases the metric M2 by reducing the material factors f t of the components (j = 1,2, … n), which are part of the equivalent mass of the turbine -see also equation (13).…”

Determining Division Location for Sectional Wind Turbine Blades

“…Conversely, the first edge natural frequencies decrease faster and faster when division locations are from 14 m to the blade tip. Figure 10b indicates that the second natural edge frequencies increase when the division location is within 6 m and between 24 and 30 m, and the increments of natural frequencies keep pace According to the scheme proposed in Section 2.3, we assumed that the stiffness of the SB-38 sectional blade increases with α of 4,6,8,9.62, and 12 as much as the original blade at the division location. At α = 9.62 is a specific characteristic for the CTC-38 blade, and the other values of 4, 6, 8, and 12 were also considered to study the impacts on natural frequencies.…”

“…For T-bolted joints, , would be larger than that of the embedded sleeve connection. According to the scheme proposed in Section 2.3, we assumed that the stiffness of the SB-38 sectional blade increases with α of 4,6,8,9.62, and 12 as much as the original blade at the division location. At α = 9.62 is a specific characteristic for the CTC-38 blade, and the other values of 4, 6, 8, and 12 were also considered to study the impacts on natural frequencies.…”

“…Meanwhile, manufacturing long blades would be beset with difficulties without special tooling and molding equipment. In fact, the cost of wind energy is not necessarily reduced by upscaling WTs based on current technology [7][8][9], due to size effects such as expensive transportation and logistics, overloads, and mass increase [8,9]. Sectional blades, as an innovative technique, are the key solution to transportation issues and to help reduce the cost of wind energy [5].…”