**About the Editor**

**Kyung Chun Kim** is a distinguished professor at the School of Mechanical Engineering of Pusan National University in Korea. He obtained his Ph.D. from the Korea Advanced Institute of Science and Technology (KAIST), Korea, in 1987. He was selected as a member of the National Academy of Engineering of Korea in 2004. His research interests include flow measurements based on PIV/LIF, turbulence, heat transfer, organic rankine cycle, wind turbine and fuel cell, and wind engineering.

## **Preface to "Design, Fabrication and Performance of Wind Turbines 2020"**

The consumption of fossil fuels has increased, resulting in high CO2 emissions and serious climate change. Research on renewable energy is currently underway in order to solve these environmental problems, and in anticipation of the depletion of fossil fuels. Wind energy is an environmentally friendly renewable energy source that does not cause environmental pollution, and its use is rapidly spreading around the world. From small-scale vertical axis wind turbines for urban usage to large-scale horizontal axis wind turbines for offshore wind farms, design, fabrication, and optimization technologies are highly required to manage wind energy effectively. Moreover, some new methods, such as for wind farm design, fluid–structure interaction, aero-acoustics, fabrication methods and performance tests by experimental and computational fluid dynamics should be implemented in modern wind turbine communities. Our basic objectives include improving the reliability, promoting the high efficiency of wind turbines, dynamic performance, reducing wind turbine generated noise and improving power generation efficiencies through high-fidelity approaches. Managing such a wide range of wind turbine scales and usages, design, fabrication, and performance test protocols for various wind turbines is a challenging issue. This Special Issue aims at encouraging researchers to address solutions to overcome the issue.

> **Kyung Chun Kim** *Editor*

*Article*

#### **Prediction and Validation of the Annual Energy Production of a Wind Turbine Using WindSim and a Dynamic Wind Turbine Model**

#### **Yuan Song 1 and Insu Paek 2,3,\***


Received: 4 August 2020; Accepted: 11 December 2020; Published: 14 December 2020

**Abstract:** In this study, dynamic simulations of a wind turbine were performed to predict its dynamic performance, and the results were experimentally validated. The dynamic simulation received time-domain wind speed and direction data and predicted the power output by applying control algorithms. The target wind turbine for the simulation was a 2 MW wind turbine installed in an onshore wind farm. The wind speed and direction data for the simulation were obtained from WindSim, which is a commercial computational fluid dynamics (CFD) code for wind farm design, and measured wind speed and direction data with a mast were used for WindSim. For the simulation, the wind turbine controller was tuned to match the power curve of the target wind turbine. The dynamic simulation was performed for a period of one year, and the results were compared with the results from WindSim and the measurement. It was found from the comparison that the annual energy production (AEP) of a wind turbine can be accurately predicted using a dynamic wind turbine model with a controller that takes into account both power regulations and yaw actions with wind speed and direction data obtained from WindSim.

**Keywords:** onshore wind farm; flow analysis; annual energy production; dynamic wind turbine model; yaw motion; peak shaver
