Multidisciplinary design optimization of offshore wind turbines for minimum levelized cost of energy

Abstract

This paper presents a method for multidisciplinary design optimization of offshore wind turbines at system level. The formulation and implementation that enable the integrated aerodynamic and structural design of the rotor and tower simultaneously are detailed. The objective function to be minimized is the levelized cost of energy. The model includes various design constraints: stresses, deflections, modal frequencies and fatigue limits along different stations of the blade and tower. The rotor design variables are: chord and twist distribution, blade length, rated rotational speed and structural thicknesses along the span. The tower design variables are: tower thickness and diameter distribution, as well as the tower height. For the other wind turbine components, a representative mass model is used to include their dynamic interactions in the system. To calculate the system costs, representative cost models of a wind turbine located in an offshore wind farm are used. To show the potential of the method and to verify its usefulness, the 5 MW NREL wind turbine is used as a case study. The result of the design optimization process shows 2.3% decrease in the levelized cost of energy for a representative Dutch site, while satisfying all the design constraints.

Combined preliminary–detailed design of wind turbines

“…In parallel, the multi-disciplinary research code Cp-Max (Code for Performance Maximization) was developed integrating a high-fidelity aeroelastic simulator together with optimization algorithms, here again evolving from a mostly structural sizing code to a more comprehensive optimization environment (Bottasso et al, 2011(Bottasso et al, , 2013(Bottasso et al, , 2015. More recently, other studies followed a multi-level approach to wind turbine design, but with the same focus of achieving a CoE reduction (Maki et al, 2012;Ashuri et al, 2014).…”

Multi-Objective Aerodynamic and Structural Optimization of Horizontal-Axis Wind Turbine Blades

“…T l d dp dLcos + dDsin = W c r C cos C sin dr dp dLsin -dDcos W c r C sin C cos dr = (3) where dpN is the force normal to the rotor plane, dpT is the force tangential to the rotor plane, ϕ is the angle between the rotor plane and the relative velocity, as shown in Figure 4. Once the geometry shape of the blade is fixed, the aerodynamic loads can be calculated using BEM theory [20,21] by dividing the blade into several independent elements.…”

“…Then, the lift and drag forces are projected into normal to and tangential to the rotor plane directions to obtain the forces dp N and dp T , as show in Equation (3): where dp N is the force normal to the rotor plane, dp T is the force tangential to the rotor plane, φ is the angle between the rotor plane and the relative velocity, as shown in Figure 4. The ultimate case is derived from the parked 50 year extreme wind condition, which can be calculated approximately by empirical formula [22]: Figure 5 shows a typical structural form of the blade cross section, which can be divided into four parts: leading edge, spar cap, shear webs and trailing edge.…”

“…With the world's ever-increasing energy demands in the presence of continuous fossil fuel shortage and environmental pollution, various renewable energy sources are currently being investigated [1][2][3][4]. Wind energy has been widely accepted because of its great advantages, such as inexhaustibility and environmental friendliness [5,6].…”

Aero-elastic Wind Turbine Design with Active Flaps for AEP Maximization

“…In the recent years several MDO frameworks have been developed to perform wind turbine multi-disciplinary optimization design (Bottasso et al (2012); Ashuri et al (2014); Merz (2015a, b) ;Fischer et al (2014); Ning et al (2014); McWilliam (2015)). In this work an optimization framework called HAWTOpt2 [Zahle et al (2016)] is utilized which enables concurrent optimization of the structure and outer shape of a wind turbine blade.…”