With the increase in wind farms in hilly terrain, it is particularly important to explore the downstream wake expansion of wind turbines in hilly terrains. This study established two complex terrain-applicable super-Gaussian wake models based on the Coanda effect and the wind speed-up phenomenon. Then, by considering the wind shear effect and the law of mass conservation, two three-dimensional (3D) super-Gaussian wake models were obtained. The 3D super-Gaussian models were used to describe the shape of the wake deficit and could reflect the wake changes in the full wake region. The introduction of the Coanda effect could reflect the sinking of the wind turbine wake on the top of a hilly terrain. And considering that the wind speed-up phenomenon could better reflect the incoming velocity distribution of the actual hilly terrain. The validation results demonstrated that the prediction results of the 3D super-Gaussian wake models had negligible relative errors compared to the measured data and could better describe the vertical and horizontal expansion changes of the downstream wake. The models established in this study can assist with the development of complex terrain models and super-Gaussian models, as well as providing guidance for power prediction and wind turbine control strategies in complex terrain.

This study utilizes a bidirectional fluid–structure interaction numerical method to investigate the hydrodynamic and energy harvesting characteristics of two tandem three rigidly connected cylinder oscillators with different inter-oscillator spacing ratios. The analysis considers inter-oscillator spacing ratios of 8, 12, and 16 within a reduced velocity range of U* = 2–13 (equivalent to flow velocities of 0.18–1.16 m/s). The research explores the hydrodynamic interference features, energy harvesting variations, and the efficiency and density of energy harvesting of both upstream and downstream three-cylinder oscillators. The findings indicate that with increasing reduced velocity and inter-oscillator spacing ratio, the mutual interference between upstream and downstream oscillators diminishes. Wake patterns observed in the two series-connected three-cylinder oscillators include 2P, 2S, and 2T patterns, with fragmented vortices and banded vortices at specific reduced velocities. The most significant disparity in energy harvesting efficiency between upstream and downstream oscillators is observed at U* = 9.

This study aimed to optimize the real-time, short-term dispatch of water-light complementary systems in plateau areas. A two-layer nested improved particle swarm optimization-stepwise optimization algorithm trial (IPSO-SOAT) model was devised to address the challenges posed by the intermittent, volatile, and random characteristics of renewable energy, leading to difficulties in renewable energy consumption and severe power cuts. The model, was employed to optimize the load distribution of complementary system power stations. The outer layer of the model employs an improved particle swarm optimization algorithm to introduce uncertainty and enhance prediction accuracy. Additionally, regional optimization and robust optimization were incorporated to improve prediction reliability. The objective function was aimed at minimizing the residual load variance. The inner layer of the model employs a stepwise optimization algorithm, coupled with a two-dimensional coding strategy for the hydropower unit, to optimize the operating status of the hydropower station unit. The objective function in this layer minimizes flow consumption. A water-light complementary system was comprehensively analyzed in the context of the southwestern plateau region, considering the complex terrain characteristics. By comparing three scenarios, the superiority and flexibility of the two-level nested model were visualized. The proposed double-layer nesting model minimizes energy and natural resource consumption while ensuring sustainability, resulting in a reduction of 15,644.265 tons of carbon dioxide emissions per year. This technological innovation makes a significant contribution to sustainable development.