Ran Han

Bio: Ran Han is an academic researcher from Nanjing University of Aeronautics and Astronautics. The author has contributed to research in topics: Turbine blade & Wind power. The author has an hindex of 3, co-authored 7 publications receiving 15 citations.

Study of Dynamic Response Characteristics of the Wind Turbine Based on Measured Power Spectrum in the Eyewall Region of Typhoons

Abstract: The present research envisages a method for calculating the dynamic responses of the wind turbines under typhoon. The measured power spectrum and inverse Fourier transform are used to generate the fluctuating wind field in the eyewall of the typhoon. Based on the beam theory, the unsteady aerodynamic model and the wind turbine dynamic model are coupled to calculate the dynamic response. Furthermore, using this method, the aeroelastic responses of a 6 MW wind turbine at different yaw angles are studied, and a 2 MW wind turbine are also calculated to verify the applicability of the results for different sizes of wind turbines. The results show that the turbulence characteristics of the fluctuating wind simulated by the proposed method is in good agreement with the actual measurement. Compared with the results simulated by the recommended power spectrum like the Kaimal spectrum, the energy distribution and variation characteristics simulated by the proposed method represent the real typhoon in a superior manner. It is found that the blade vibrates most violently at the inflow yaw angle of 30 degrees under the coupled effect of the aerodynamic, inertial and structural loads. In addition, the load on the tower exceeds the design limit values at the yaw angles of both 30 degrees and 120 degrees.

Uniform Decomposition and Positive-Gradient Differential Evolution for Multi-Objective Design of Wind Turbine Blade

Abstract: Convergence performance and optimization efficiency are two critical issues in the application of commonly used evolution algorithms in multi-objective design of wind turbines. A gradient-based multi-objective evolution algorithm is proposed for wind turbine blade design, based on uniform decomposition and positive-gradient differential evolution. In the uniform decomposition, uniformly distributed reference vectors are established in the objective space to maintain population diversity so that the population aggregations, which are commonly observed for wind turbine blade design using gradient-free algorithms, are minimized. The positive-gradient differential evolution is introduced for population evolution to increase optimization efficiency by guiding the evolutionary process and significantly reducing searching ranges of each individual. Two-, three- and four-objective optimizations of 1.5 MW wind turbine blades reveal that the proposed algorithm can deliver uniformly distributed optimal solutions in an efficient way, and has advantages over gradient-free algorithms in terms of convergence performance and optimization efficiency. These advantages increase with the optimization dimension, and the proposed algorithm is more suitable for optimizations of small size populations, thus remarkably enhancing the design efficiency.

Centrifugal wind turbine blade jet flow power increasing device

Abstract: The invention discloses a centrifugal wind turbine blade jet flow power increasing device. The centrifugal wind turbine blade jet flow power increasing device comprises a wind turbine blade. The windturbine blade is internally provided with a duct along a blade variable pitch axis of the wind turbine blade, and an air inlet hole is formed in the surface of a blade root of the wind turbine blade in a machined mode. A vent hole is formed in the surface of a blade tip of the wind turbine blade in a machined mode, and the air inlet hole and the vent hole both communicate with the duct. When the wind turbine blade rotates, pressure difference is generated at the blade root and the blade tip of the wind turbine blade due to the centrifugal force effect, part of air flow passing through the blade root and the blade tip of the wind turbine blade is sucked by the air inlet hole, so that separation flow at the blade root of the wind turbine blade is reduced; and the air flow sucked by the air inlet hole is discharged from the vent hole after passing through the duct, so that the formation of a tip vortex of the wind turbine blade is weakened or blocked, and the centrifugal wind turbine blade jet flow power increasing is realized. The centrifugal wind turbine blade jet flow power increasing device has simple structure and implementation, clear technical principle, low manufacturing cost,no maintenance and broad application prospects.

Minimizing Energy Loss by Coupling Optimization of Connection Topology and Cable Cross-Section in Offshore Wind Farm

Abstract: The cable cross section of an offshore wind farm power system is conventionally determined on the basis of the maximum current carrying capacity. However, this criterion cannot be matched and optimized with connection topology, which may lead to a large overall resistance level in the topology, thereby causing severe energy loss. In this pursuit, the present work envisages the establishment of a coupling optimization method of connection topology and cable cross-section planning for the first time. Based on this method, the power system of a small discrete wind farm is optimized and its results are compared with the results of the traditional design methods. The results indicate that an optimal matching of connection topology and cable cross section can be achieved using the proposed method. Besides, the optimal topology obtained uses more branches, and the large cross-section cables are reasonably used on the large-current cable segments, thus dramatically reducing the energy loss and minimizing the total cost of the power system. The proposed method is very versatile and suitable for the optimization of power systems containing any number of wind turbines and substations. Moreover, it can be combined with any evolutionary algorithm.

A novel global optimization algorithm and data-mining methods for turbomachinery design

Abstract: A new multi-objective, multi-disciplinary global optimization strategy is proposed to address the high-dimensional, computationally expensive black box problem (HEB) in turbomachinery design. The strategy consists of an adaptive sampling hybrid optimization algorithm (ASHOA), two data-mining techniques, a 3D blade parameterization method, and the aerodynamic/mechanical codes. Firstly, the ASHOA is established by integrating a novel adaptive sampling Kriging metamodel and a new hybrid optimization method. Secondly, two data-mining methods (analysis of variance (ANOVA) and self-organizing map (SOM)) are applied to set the initial design space and optimization objectives of the transonic centrifugal compressor. A refined design space and objective parameters of the optimization problem are eventually obtained. Finally, the optimization process of a transonic centrifugal compressor is carried out based on the refined design space and objectives using ASHOA. The results show that the search efficiency of the optimization strategy is 2–10 times higher when compared to other excellent optimization algorithms. For the optimized compressor, both isentropic efficiency and total pressure ratio at design condition are improved by 1.61% and 4.13%, respectively, and the maximum stress decreases by 9.68%.

Wind Farm Cable Connection Layout Optimization with Several Substations

Abstract: Green energy has become a media issue due to climate changes, and consequently, the population has become more aware of pollution. Wind farms are an essential energy production alternative to fossil energy. The incentive to produce wind energy was a government policy some decades ago to decrease carbon emissions. In recent decades, wind farms were formed by a substation and a couple of turbines. Nowadays, wind farms are designed with hundreds of turbines requiring more than one substation. This paper formulates an integer linear programming model to design wind farms’ cable layout with several turbines. The proposed model obtains the optimal solution considering different cable types, infrastructure costs, and energy losses. An additional constraint was considered to limit the number of cables that cross a walkway, i.e., the number of connections between a set of wind turbines and the remaining wind farm. Furthermore, considering a discrete set of possible turbine locations, the model allows identifying those that should be present in the optimal solution, thereby addressing the optimal location of the substation(s) in the wind farm. The paper illustrates solutions and the associated costs of two wind farms, with up to 102 turbines and three substations in the optimal solution, selected among sixteen possible places. The optimal solutions are obtained in a short time.

A Competitive-Cooperative Game Method for Multi-Objective Optimization Design of a Horizontal Axis Wind Turbine Blade

Abstract: This paper presents a multi-objective optimization model of a wind turbine blade based on blade's parameterized finite element model, where annual energy production and blade mass are the objective functions, and aerodynamic and structural parameters are the design variables. In this study, the maximum axial thrust, strain, displacement, and first-order natural frequency of blade are selected as constraints. A novel competitive-cooperative game method is proposed to obtain the optimal preference solution. In this method, a new exploration method of player's strategy space named `correlation analysis under fuzzy k-means clustering' is proposed, and the payoff functions are constructed according to competitive and cooperative behaviors. Two optimization schemes with preference objectives are obtained and all goals showed clear improvements over the initial solutions, and this method reveals the relationship between blade shape and desired performance. More deeply, dynamic sensitivities of various design variables to objective functions are obtained for different blade shapes.