Search Results (10)

High-speed permanent magnet motors, due to their high speed, compact size, and light weight, are increasingly widely used in renewable energy systems, electric pump drives, fuel cell air compressors, and other fields. As a core component of high-speed permanent magnet motors, the reasonable design of the rotor system structure directly affects motor stability. To ensure the safe and reliable operation of high-speed permanent magnet motors, this paper designs the structure of a certain type of high-speed electric pump rotor. First, the actual interference amount between the rotor permanent magnet and the high-temperature alloy sleeve under high-speed and high-temperature conditions is considered, and radial and tangential stress analyses are performed on both the rotor and high-temperature alloy sleeve to determine the optimal interference amount. Second, based on rotor dynamics and fluid–structure coupling theory, the natural frequency and critical speed of rotors under wet and dry modals are studied; on this basis, harmonic response analysis and fatigue assessment were conducted; furthermore, an elastoplastic mechanical model of the rotor sleeve is introduced to analyze the effects of interference amount and rotational speed on the sleeve’s yield failure; finally, the dynamic safety of the high-speed rotor structure is verified through modal tests and overspeed operation tests. The results show that the optimal interference amount for the rotor is 0.02 mm; the first-order critical speeds in both dry and wet modals are well above the rated speed of 40,000 rpm, with no risk of resonance; the minimum cycle for fatigue life is 6.9 × 10⁵, meeting usage requirements; the equivalent force on the rotor sleeve increases with speed and interference amount; when the speed exceeds 44,000 rpm, the sleeve undergoes plastic deformation and failure; modal test error is less than 5%. This paper provides theoretical basis and experimental support for the rotor structure design and strength evaluation of high-speed permanent magnet motor drive equipment. Full article

Piston engine system identification models are crucial for autonomous and control-oriented applications. However, piston engines exhibit relatively unstable behavior, which may lead to overspeed during open-loop operation. In this study, system identification of a piston engine is investigated on a piston engine–dynamometer test bench. The identification process is carried out under closed-loop conditions to ensure safe and reliable operation. Known system parameters are utilized to transform the closed-loop system into an equivalent open-loop representation. Three system identification models—a State-Space model, a nonlinear ARX model, and a Hammerstein–Wiener model—are employed and comparatively evaluated. The identified models are validated based on their closed-loop responses. Subsequently, a gain scheduled cruise controller is designed using the identified model and implemented on an engine dynamic model. Finally, a disturbance observer is integrated into the cruise controller to enhance disturbance rejection performance. The disturbance observer is developed based on the identified system model. Full article

Small wind turbines operating at low heights frequently experience rapidly fluctuating and highly turbulent wind conditions that challenge conventional reactive pitch-control strategies. Under these non-stationary regimes, sudden gusts produce overspeed events that increase mechanical stress, reduce energy capture, and compromise operational safety. Addressing this limitation requires a control scheme capable of anticipating aerodynamic disturbances rather than responding after they occur. This work proposes a hybrid anticipatory pitch-control approach that integrates a conventional PI regulator with a data-driven rotor-speed prediction model. The main novelty is that short-term rotor-speed forecasting is embedded into a standard PI loop to provide anticipatory action without requiring additional sensing infrastructure or changing the baseline control structure. Using six years of real wind and turbine-operation data, an optimized Random Forest model is trained to forecast rotor speed 20 s ahead based on a 60 s historical window, achieving a prediction accuracy of RMSE = 0.34 rpm and R² = 0.73 on unseen test data. The predicted uses a sliding-window representation of recent wind–rotor dynamics to estimate the rotor speed at a fixed horizon (t + Δt), and the predicted signal is used as the feedback variable in the PI loop. The method is validated through a high-fidelity MATLAB/Simulink model of 14 kW small horizontal-axis wind turbine, evaluated under four wind scenarios, including two previously unseen conditions characterized by steep gust gradients and quasi-stationary high winds. The simulation results show a reduction in overspeed peaks by up to 35–45%, a decrease in the integral absolute error (IAE) of rotor speed by approximately 30%, and a reduction in pitch-actuator RMS activity of about 25% compared with the conventional PI controller. These findings demonstrate that short-term AI-based rotor-speed prediction can significantly enhance safety, dynamic stability, and control performance in small wind turbines exposed to highly variable atmospheric conditions. Full article

The turbine disk-drum is one of the key components of an aero-engine and its assembly is connected with high-strength refined screws. But due to the uncoordinated rotation and deformation, the screws have abnormal wear damage. Through detailed contact stress analysis of screw body and component level using the finite element method, combined with experimental observation, the mechanism of wear damage of screw surface in screws is determined. It mainly includes the following: Firstly, the finite element method is used to calculate the deformation and stress distribution of the connecting screw of the turbine disk-drum assembly. Then, after the overspeed test, the morphology of the screws disassembled from the disk-drum assembly is evaluated. It was found that the wear degree in the circumferential direction and axial direction of the screw was quite different, that is, the screw wear experiment was consistent with the finite element analysis results. Finally, the influence of different rotation states and screw tightening states on screw wear was compared and analyzed. Conclusions obtained in this paper will be helpful to improve the assembly reliability of turbine drum. Full article

The airworthiness standards of the transport category airplanes stipulate that the high energy rotor equipment must be of the sufficient containment capacity. It is of great importance to study the containment and weight reduction for the air turbine starter. In this paper, based on an OSF design, Kriging response surface model and MOGA algorithm, a neck structure optimal design method was proposed for the air turbine wheel. Using the optimal design method, the optimal structural parameters were suggested as the design parameters, and verified by the over-speed burst test. The maximum errors of the burst speeds between the experimental and design values are less than 2%, and the neck structure turbine wheel breaks in the neck as expected, validating the accuracy of the optimal design method. Then, the effects of turbine wheel burst modes on the containment were investigated quantitatively, and verified by the containment tests. Based on the experimental and simulation results, the containment design method was proposed for the neck structure turbine wheel. The results show that compared with the trisection wheel burst, the rim burst dramatically decrease the mass and initial kinetic energy of burst released fragments by 63.3% and 24.8%, thereby greatly reducing the thickness and the mass of the containment ring by 29.5% and 29.1%. Full article

Over the past few years, there has been significant interest in the importance of reversible hydro-pumping systems due to their favorable flexibility and economic and environmental characteristics. When designing reversible lines, it is crucial to consider dynamic effects and corresponding extreme pressures that may occur during normal and emergency operating scenarios. This research describes essentially the turbine operation, although various boundary elements are mathematically formulated and presented to provide an understanding of the system complexity. Different numerical approaches are presented, based on the 1D method of characteristics (MOC) for the long hydraulic circuit, the dynamic turbine runner simulation technique for the behavior of the power station in turbine mode and the interaction with the fluid in the penstock, and a CFD model (2D and 3D) to analyze the flow behavior crossing the runner through the velocity fields and pressure contours. Additionally, the simulation results have been validated by experimental tests on different setups characterized by long conveyance systems, consisting of a small scale of pumps as turbines (at IST laboratory) and classical reaction turbines (at LNEC laboratory). Mathematical models, together with an intensive campaign of experiments, allow for the estimation of dynamic effects related to the extreme transient pressures, the fluid-structure interaction with rotational speed variation, and the change in the flow. In some cases, the runaway conditions can cause an overspeed of 2–2.5 of the rated rotational speed (N_R) and an overpressure of 40–65% of the rated head (H_R), showing significant impacts on the pressure wave propagation along the entire hydraulic circuit. Sensitivity analyses based on systematic numerical simulations of PATs (radial and axial types) and reaction turbines (Francis and Kaplan types) and comparisons with experiments are discussed. These evaluations demonstrate that the full-load rejection scenario can be dangerous for turbomachinery with low specific-speed (n_s) values, in particular when associated with long penstocks and fast guide vane (or control valve) closing maneuver. Full article

Rotating parts of aeroengines need to have a high speed margin according to the civil aviation airworthiness regulations. Previous studies on burst speed are based on mechanical properties of standard specimens. In this paper, a new method for predicting burst speed by means of a tensile test of a simulative specimen is proposed, and the predicted results are compared with the traditional method. The results show that the stress gradient of the designed simulative specimen and the assessment location of vortex reducer are in good agreement, which indicates that they have similar stress characteristics. The burst speed predicted by the new method is greater than the traditional method. Both prediction methods can provide a reference for such a structure in the design stage. In addition, the overspeed test of a vortex reducer is carried out, and the results verify that it still has sufficient strength reserves at 120% relative speed. Full article

A novel direct reactive power control strategy based on the three-level inverter topology (DRPC-3N) is proposed for a doubly fed induction generator (DFIG)-based wind power plant system. The robustness against parametric variations and control performances of the presented methodology are analyzed under random wind speeds, taking into account the effect of the heating of the windings as well as the saturation of the magnetic circuit. The performance indices include obtaining a sinusoidal AC-generated current with low THD and less ripples in the output. Moreover, the generator can be considered as a reactive power compensator, which allows for the controlling of the active and reactive power of the stator side connected directly to the grid side using only the rotor converter. In this study, unpredictable conduct of the wind velocity that forces the DFIG to operate through all modes of operation in a continual and successive way is considered. The received wind power is utilized to extract the optimum power by using an appropriate MPPT algorithm, and the pitch angle control is activated during the overspeed to restrict the produced active power. The simulation tests are performed under Matlab/Simulink and the presented results show the robustness and effectiveness of the new DRPC strategy with the proposed topology, which means that the performances are more sophisticated. Full article

Zero-voltage ride through (ZVRT) is the extreme case of low-voltage ride through (LVRT), which represents the optimal grid-connection capability of wind turbines (WTs). Enforcing ZVRT will improve the dynamic performance of WTs and therefore significantly enhance the resiliency of renewable-rich grids. A control scheme that includes a pitch system is an essential control aspect of WTs riding through voltage dips; however, the existing control scheme with a pitch system for LVRT cannot distinguish between a ZVRT status and a power-loss condition, and, consequently, does not meet the ZVRT requirements. A system-level control scheme with a pitch system for ZVRT that includes pitch system modeling, control logic, control circuits, and overspeed protection control (OPC) is proposed in this paper for the first time in ZVRT research. Additionally, the field data are shared, a fault analysis of an overspeed accident caused by a voltage dip that describes the operating status at the WT-collapse moment is presented, and some existing WT design flaws are revealed and corrected by the fault analysis. Finally, the pitching performance during a ZVRT, which significantly affects the ZVRT performance of the WT, is obtained from laboratory and field tests. The results validate the effectiveness of the proposed holistic control scheme. Full article

There is significant potential for an increase in the use of kilowatt-class small wind turbines (SWTs) in Japan due to reduced limitations with respect to installation, despite their high cost. At this stage, the Japanese grid code has not been considered sufficiently with respect to grid-connected SWTs, and the addition of fault ride-through (FRT) requirements for SWTs has been requested. Moreover, the FRT of SWTs is challenging to achieve owing to the low inertia constants when compared with those of large-scale wind turbines, which result in significant acceleration of the rotor speed and an increase in the input voltage of the power conditioning system (PCS) during FRT operation. In this study, FRT field tests were conducted on SWT systems against a voltage dip with a duration of $~1$ s, and it was confirmed that the SWT systems satisfied the FRT requirements for photovoltaic (PV) systems connected to low-voltage distribution lines in Japan. The behaviors of the rotational speed of the SWTs and the PCS input voltage in an FRT operation were then analyzed, and it was noted that the increase in the PCS input voltage with the overspeed of the turbine can reach the upper limit and make the PCS cease operation, which indicates failure of the FRT. The overvoltage, therefore, requires restriction using a method such as pitch control, furling, and electrical and/or mechanical brakes. Full article