Search Results (35)

Variations in wind-turbine rotor speed and converter power margin under different operating conditions constrain the frequency-support power output of wind turbines, thereby affecting the controllability and stability of the frequency-support response. To address this problem, this paper proposes a dual virtual synchronous generator (VSG) coordinated control method for energy-storage doubly fed induction generator wind turbines based on frequency-support power-response equivalence. First, frequency-support power-response models are established for the VSGs implemented at the rotor-side converter and the grid-side converter to describe the active-power dynamic characteristics of the two frequency-support channels. Second, using the target inertial-support power response as the reference, the dual-VSG parameter configuration is transformed into a power-response consistency optimization problem. Furthermore, considering rotor speed, state of charge (SOC), and the grid-side converter upward power margin, the inertia-support and primary frequency regulation power contributions are assigned between the stator and grid-side converter channels. Hardware-in-the-loop validation results show that the proposed method coordinates the dual-channel frequency-support power output under four typical operating conditions with high/low wind speeds and high/low SOC levels, maintains a consistent frequency-support power response, and achieves controllable and stable frequency support over a wide operating range. Full article

This study investigates whether aerodynamic interaction effects in an interlocked (negative-gap) counter-rotating dual Savonius rotor configuration can improve the efficiency of drag-based vertical-axis wind turbines in urban wind conditions. Two-dimensional Computational Fluid Dynamics (CFD) simulations were performed in ANSYS Fluent 2025 R2 using both steady and unsteady RANS approaches, including dynamic meshing to enable collision-free rotation in the interlocked overlap region. The numerical setup was first validated for a single two-bucket reference rotor against published experimental data of torque and power coefficients and subsequently applied to dual-rotor configurations with negative gap distances. The results show that the dual-rotor arrangement redistributes torque production over the azimuth angle and yields a smoother and consistently positive mean static torque coefficient, indicating improved self-starting behavior compared to the single rotor. Under transient operation, the dual-rotor configuration yields higher power coefficient values across the entire investigated tip-speed ratio range. The highest performance gain is observed at a tip-speed ratio of $\lambda \approx 1.0$, where the peak power coefficient increases from $c_p\approx 0.25$ (single-rotor) to $c_p\approx 0.32$ (dual-rotor), corresponding to an improvement of the power coefficient of about $\mathsf{\Delta }{c}_p/c_{p0}\approx 28\%$. Full article

This work investigates the performance degradation of dual vertical axis wind turbines at low tip speed ratios using numerical simulation using two-dimensional computational fluid dynamics (CFD). In order to address this problem, it suggests a unique deflector configuration and arrangement. The results show a 21.33% improvement in self-starting potential at low TSRs when dual-configuration deflectors are deployed close to the twin rotors. Additionally, the average torque coefficient increases by 24.31% and the peak power coefficient increases by 53.12%, indicating a significant improvement in performance at high tip speed ratios. While curved deflectors on both sides provide converging channels that increase flow volume and dynamic pressure in the downwind zone, the central deflector decreases reverse airflow in the midsection. The proposed deflector arrangement also exhibits great potential for the compact layout of wind farm arrays; the accelerated wake recovery characteristic is beneficial to improving the overall efficiency of wind farms. With important ramifications for the advancement of renewable energy technology, this work provides fresh insights into dual vertical axis wind turbine optimization. Full article

A gyroscopic stabilizer generates an anti-roll moment by regulating the precession angle of a high-speed rotor. By computing the precession-angle command in real time, the controller can effectively suppress roll motion. However, research on the application of gyroscopic stabilizers to floating wind turbines remains limited. In this study, the operating mechanism of a gyroscopic stabilizer is modeled, and frequency-domain stability analyses are conducted for the system dynamics both before and after the installation of the stabilizer. A pole-placement-based controller is designed to achieve active stabilization of wave-induced platform motions by adjusting the rotor precession angle. Based on wave spectrum analysis, numerical simulations are performed to compare system responses with and without the active controller under different sea conditions. The results demonstrate that the proposed anti-roll control strategy exhibits robust performance and can increase the roll reduction rate by at least a factor of two across a range of sea states. In addition, the anti-roll effectiveness is influenced by rotor speed and environmental conditions, with higher reduction rates achieved at higher rotor speeds, larger wave heights, and longer wave periods. In addition, we adopt a dual-gyro configuration to cancel yaw-interference moments, and the proposed controller is feedback-based (platform motion only), which is suitable for retrofit applications without requiring wave-preview sensors. Full article

Accurate inflow wind conditions are essential for operational wind farms. However, wind conditions from the Supervisory Control and Data Acquisition (SCADA) system are significantly affected by rotor-induced disturbances and thus cannot reliably represent the true inflow. Although LiDAR can directly measure inflow wind conditions, its data availability is highly sensitive to environmental conditions, frequently leading to insufficient valid samples. Existing studies generally apply the Nacelle Transfer Function (NTF) to empirically correct SCADA wind speed, yet its accuracy remains limited. Consequently, this study proposes a deep learning model for LiDAR-referenced inflow wind condition estimation from SCADA data. First, variations in LiDAR data availability and their influencing factors are systematically analyzed. The deviations and correlations between SCADA data and LiDAR measurements are quantitatively characterized. Subsequently, a deep learning model is developed, employing a time–frequency dual-branch residual network to extract features from SCADA data, while incorporating the Gram matrix as an additional input to provide auxiliary information. Finally, the proposed method is validated using measurements from two offshore turbines with different rated capacities. The results demonstrate that the proposed approach outperforms comparative methods, enabling more accurate estimation of inflow wind speed and direction. Full article

This study proposes a hybrid forecast-enabled adaptive crowbar coordination strategy to enhance low-voltage ride-through (LVRT) performance of doubly fed induction generator (DFIG) wind turbines. A unified electro-mechanical model in the αβ/dq frames with dual closed-loop control for rotor- and grid-side converters is built in MATLAB/Simulink (R2018b), and LVRT constraints on current safety and DC-link energy are explicitly formulated, yielding an engineering crowbar-resistance range of 0.4–0.8 p.u. On the forecasting side, a CEEMDAN-based decomposition–modeling–reconstruction pipeline is adopted: high- and mid-frequency components are predicted by a dual-stream Informer–LSTM, while low-frequency components are modeled by XGBoost. Using six months of wind-farm data, the hybrid forecaster achieves best or tied-best MSE, RMSE, MAE, and R² compared with five representative baselines. Forecasted power, ramp rate, and residual-based uncertainty are mapped to overcurrent and DC-link overvoltage risk indices, which adapt crowbar triggering, holding, and release in coordination with converter control. In a 9 MW three-phase deep-sag scenario, the strategy confines DC-link voltage within ±3% of nominal, shortens re-synchronization from ≈0.35 s to ≈0.15 s, reduces rotor-current peaks by ≈5.1%, and raises the reactive-support peak to 1.7 Mvar, thereby improving LVRT safety margins and grid-friendliness without hardware modification. Full article

Savonius drag-based rotors, a type of vertical-axis wind turbine (VAWT), are well-suited for urban environments—particularly residential rooftops—owing to their compact design and ability to capture wind from all directions. However, their relatively low efficiency and narrow operational range pose significant challenges, such as limited energy output under variable wind conditions and reduced performance across a broad range of tip speed ratios. To address these issues, this study explores flow augmentation using strategically placed deflectors, referred to as Wind Accelerators and Guiding Rotor Houses (WAG-RHs). Four different configurations, including double, triple, oblique, and straight designs, were evaluated against both omni-directional guide vanes (ODGVs) and a conventional rotor. The findings show that the ODGV configuration successfully extends the operational range from a tip speed ratio of 0.5 to 0.6—termed the extended performance point (EPP)—and increases the power coefficient ($C_p$) by up to 300% compared to the conventional design. Among all setups, the straight WAG-RH configuration proved most effective, not only achieving the EPP but also delivering a 385% and 264.3% increase in local and AVE $C_p$ values, respectively compared to the conventional rotor. It also outperformed the ODGV-equipped rotor by 25%, thanks to its radial and dual-plane arrangement. Full article

Improvements in the aerodynamic performance of the H-Darrieus turbine are crucial to address future energy requirements. This work aims to optimize the behavior of two adjacent turbines through the addition of a dual H-Darrieus rotor. The first rotor is composed of three NACA 0021 blades, while the second comprises a single Eppler 420 blade. This study focuses on 2D CFD simulation based on the solution of the unsteady Reynolds-averaged Navier–Stokes (URANS) equations, using the sliding mesh method and $k-\omega$ SST turbulence model. The simulation results indicate a 17% improvement in the efficiency of the two turbines integrating dual rotors, compared to the two isolated turbines, for $\alpha$ = 0°. Moreover, the power coefficient ${ (C}_P)$ reaches maximum values of 0.49, 0.42, and 0.40 for angles of attack of 30°, 25°, and 20°, respectively, at TSR = 2.51. Conversely, the selection of an optimal angle of attack allows the efficiency of the two H-Darrieus turbines to be increased. It is also shown by the results that the effect of stagnation is reduced and lift is maximized when the optimum distance between two adjacent turbines is chosen. Moreover, the overall aerodynamic performance of the system is enhanced by the potential of a dual-rotor configuration, and the wake between the two turbines is disrupted, which can result in a decrease in energy production within wind farms. Full article

In this paper, the performance of the Independent Dual Rotor Wound Field Flux Switching Generator (IDRWFFSG) under locked rotor fault scenarios and counter-rotating operational direction for fault withstand capability is investigated. The IDRWFFSG and the locked rotor fault scenarios are defined, and the magnetic path formation is explained. An integrated mathematical and electromagnetic modelling of the generator characteristics performance comprising torque quality, output power, efficiency and power factor are undertaken, based on the finite element method (FEM) under fault conditions. The electromagnetic characteristics are investigated independently for the inner and outer rotors under locked conditions while the counterpart rotor is rotated in both clockwise (CW) and counterclockwise (CCW) directions. The analysis confirms that CCW offers a comparatively better response than CW, with excellent locked rotor fault withstand capability. In the case of CCW operation, the average torque, output power, efficiency, and power factor are improved. Based on the results, it is determined that the rotational direction of the rotor is selected depending on the prerequisite demand of high efficiency, high power factor, and high output power when one of the rotors goes under a locked condition. Finally, a test prototype is developed to validate the predicted electromagnetic characteristics, of which the measured results confirm the effectiveness of the IDRWFFSG fault withstand capability study. Full article

The conversion of air currents through wind turbine technology stands as one of the most significant and effective means of generating green electricity. Wind turbines featuring a horizontal axis exhibit the greatest installed capacity. The study establishes a mathematical model for large wind turbines, categorized by megawatt output, utilizing measured data for key parameters, including wind speed, power output from the generator, and rotational speed. The analysis of the system’s behavior on startup—the cut-in wind speed, is conducted by transitioning the electric generator into motor mode. A mathematical model has been established for the dual-powered motor configuration, wherein both the stator and rotor are connected to a common frequency network, facilitating a shift to synchronous motor functionality. The equation that describes the kinetic moment highlights the importance of attaining optimal velocity, while simultaneously accounting for variations in the load angle. These fluctuations are observable in both the power output and the electrical currents. The simulations that have been processed are derived from experimental data, specifically inputs obtained from a 1.5 MW wind turbine located in the Oravita region of southwestern Romania. The paper thus outlines essential elements concerning the functionality of high-power wind turbines that utilize wound rotor induction generators, aiming to guarantee optimal performance from the moment the wind speed reaches the cut-in threshold. Full article

Self-starting capability has consistently presented a significant challenge for Darrieus vertical axis wind turbines (VAWTs). One advantageous approach to addressing this problem is the design of a hybrid Darrieus–Savonius VAWT. The hybrid VAWT enhances self-starting capability by increasing the power coefficient ($C_p$) within the low tip speed ratio (TSR) range and the torque coefficient ($C_m$) at initial azimuth angles, when the blades transition from windward to upwind position. A significant challenge associated with conventional hybrid VAWTs, in which both rotors are mounted on a single shaft, is the decline in efficiency at the high-TSR range. This inefficiency is due to the performance limitations of the inner Savonius rotor, which is designed to function at low angular velocities. In the high-TSR range, the vorticity generation around Savonius rotor buckets adversely impacts the Darrieus rotor performance and the hybrid VAWT. A dual-shaft configuration is proposed to mitigate this issue, which utilizes a drivetrain transmission system to prevent the Savonius rotor from exceeding its optimal angular velocity, thus acting as a control mechanism. The findings indicate that implementing the dual-shaft rotor resulted in a 35% improvement in $C_p$ within the low-TSR range and a 25% enhancement in the high-TSR range. This improvement is achieved when the inner rotor’s angular velocity is maintained at $19.79 \mathrm{rad}/\mathrm{s}$, which has been determined to be the optimal value for the inner rotor. Full article

In this paper, the performance of a Dual-Stator Winding Synchronous Reluctance Generator (SynRG) suitability for off-grid wind power generation is analyzed. The rotor of the SynRG has a slitted-rotor core to improve selected vital performance parameters. The SynRG with a slitted-rotor core was modeled using a two-dimensional (2D) Finite Element Method (FEM) to study the electromagnetic performance of key parameters of interest. To validate the FEA results, a prototype of the SynRG with a slitted rotor was tested in the laboratory for no-load operation and load operation for unity, lagging, and leading power factors. To evaluate the capability of the SynRG with a slitted-rotor core to operate in a wind turbine environment, the machine was modeled and simulated in Matlab/Simulink (R2023a) for dynamic responses. The FEA results reveal that the SynRG with a slitted-rotor core, compared with the conventional SynRG with the same ratings and specifications, reduces the torque ripple by 24.51%, 29.72%, and 13.13% when feeding 8 A to a load with unity, lagging, and leading power factors, respectively. The FEA results also show that the induced voltage on no-load of the SynRG with a slitted-rotor core, compared with the conventional SynRG of the same ratings and specifications, increases by 10.77% when the auxiliary winding is fed by a capacitive excitation current of 6 A. Furthermore, the same results show that with a fixed excitation capacitive current of 6 A, the effect of armature reaction of the SynRG with a slitted-rotor core is demagnetizing when operating with load currents having a lagging power factor, and magnetizing when operating with load currents having unity and leading power factors. The same patterns have been observed in the experimental results for different excitation capacitance values. The Matlab/Simulink results show that the SynRG with a slitted-rotor core has a quicker dynamic response than the conventional SynRG. However, a well-designed pitch-control mechanism for the wind turbine is necessary to account for changes in wind speeds. Full article

This paper presents the results of experimental, analytical, and numerical studies on determining the driving torque and power of a vertical-axis wind turbine (VAWT) with planetary blade motion forced by a carousel rotor. First, experimental studies in the wind tunnel laboratory were conducted to determine the tip speed ratio λ for the real-scale wind turbine model under self-starting conditions. Then, an analytical kinematic model of the turbine was developed. Finally, computational fluid dynamics (CFD) analysis was conducted to verify the analytical approach and examine aerodynamic interferences between particular turbine blades. The main objective of the study was to verify the accuracy of the simplified analytical approach to calculating the driving torque and turbine power compared to the numerical results based on 2D analysis using computational fluid dynamics. The obtained results showed good agreement considering the modeling of the motion of the three dual-coherent blades of the wind turbine. Comparing the analytical and CFD approaches, the error in determining the average driving torque and the average turbine power was about 1%. An additional objective of the study was to use the developed analytical method to calculate the starting torque and demonstrate the main advantage of the carousel wind rotor, which is its higher starting torque compared to the H-type Darrieus rotor. Full article

This paper investigates an adaptive disturbance rejection control (ADRC) strategy for dual-variable power smoothing for hydraulic wind turbine systems deployed in marine environments. Initially, fluctuations in wind speed induce variations in the output torque and rotational speed of the wind turbine; this study examines the interaction between these two variables and subsequently decouples them. An innovative dual-variable anti-disturbance control strategy is proposed, which independently regulates the pitch angle of the rotor and the swing angle of the variable motor to mitigate fluctuations in both speed and torque, thereby achieving a smoother system output power. The simulation results obtained through MATLAB/Simulink (Version R2022a) indicate that employing the proposed control strategy leads to an 8.31% reduction in power generation compared to optimal power tracking strategies while enhancing output power stability by 56.67%. Furthermore, the effective smoothing of power fluctuations is accomplished without necessitating energy storage devices. Finally, the effectiveness of the power smooth output control strategy proposed in this paper was verified based on a semi-physical simulation experimental platform for a 30 kW hydraulic wind turbine. The control method proposed in this paper provides a theoretical basis for the promotion and application of hydraulic wind turbines with stable power output. Full article

This study analyzes the performance degradation of traditional hybrid wind turbines under high blade-tip-speed ratio conditions and proposes solutions through two-dimensional Computational Fluid Dynamics (CFD) simulations. It also introduces the design of two innovative asynchronous-hybrid dual-rotor wind turbines. The results indicate a remarkable 98.5% enhancement in torque performance at low blade-tip-speed ratios with the hybrid wind turbine model. However, as the blade-tip-speed ratio increases, it leads to negative torque generation within the inner rotor of the conventional design, resulting in a reduction of the power coefficient by up to 13.1%. The introduction of the new wind turbine design addresses this challenge by eliminating negative torque at high blade-tip-speed ratios through adjustments in the inner rotor’s operating range. This modification not only rectifies the negative torque issue but also enhances the performance of the outer rotor in the leeward region, consequently boosting the overall power coefficient. Moreover, the optimized inner rotor configuration effectively disrupts and shortens the wake length by 16.7%, with this effect intensifying as the rotational speed increases. This optimization is pivotal for enhancing the efficiency of multi-machine operations within wind farms. Full article