scholarly journals Analysis of a Horizontal-Axis Tidal Turbine Performance in the Presence of Regular and Irregular Waves Using Two Control Strategies

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 367 ◽  
Author(s):  
Stephanie Ordonez-Sanchez ◽  
Matthew Allmark ◽  
Kate Porter ◽  
Robert Ellis ◽  
Catherine Lloyd ◽  
...  
Keyword(s):  
Control Strategies ◽  
Average Power ◽  
Bending Moment ◽  
Horizontal Axis ◽  
Torque Control ◽  
Irregular Waves ◽  
Control Mode ◽  
Peak Period ◽  
Irregular Wave ◽  
Tidal Turbine

The flow developed on a tidal site can be characterized by combinations of turbulence, shear flows, and waves. Horizontal-axis tidal turbines are therefore subjected to dynamic loadings that may compromise the working life of the rotor and drive train components. To this end, a series of experiments were carried out using a 0.9 m horizontal-axis tidal turbine in a tow tank facility. The experiments included two types of regular waveforms, one of them simulating an extreme wave case, the other simulating a more moderate wave case. The second regular wave was designed to match the peak period and significant wave height of an irregular wave which was also tested. Measurements of torque, thrust, and blade-bending moments were taken during the testing campaign. Speed and torque control strategies were implemented for a range of operational points to investigate the influence that a control mode had in the performance of a tidal stream turbine. The results showed similar average power and thrust values were not affected by the control strategy, nor the influence of either the regular or irregular wave cases. However, it was observed that using torque control resulted in an increase of thrust and blade root bending moment fluctuations per wave period. The increase in fluctuations was in the order of 40% when compared to the speed control cases.

Tidal Turbine Load Variability in Following and Opposing Irregular Wave Conditions

2020 ◽  
Author(s):  
Samuel Draycott ◽  
Jeffrey Steynor ◽  
Anup Nambiar ◽  
Brian Sellar ◽  
Vengatesan Venugopal
Keyword(s):  
Wave Interaction ◽  
Irregular Waves ◽  
Current Direction ◽  
Irregular Wave ◽  
Tidal Turbines ◽  
Wave Parameters ◽  
Load Distributions ◽  
Equivalent Wave ◽  
Tidal Turbine ◽  
Turbine Design

Abstract Waves induce large loads on tidal turbines, yet the effect of irregular waves, particularly those which oppose the current direction, have received little attention. Here we experimentally assess the loading resulting from 24 irregular combined wave-current cases, statistically presenting the load variability acting on a 1:15 scale tidal turbine. Comparisons are made between following and opposing conditions of equivalent wave parameters, and the effect of varying frequency and amplitude is assessed. Example load distributions are also shown, along with streamwise variation of significant wave height around the turbine. It is concluded that both opposing and following conditions must be assessed to effectively de-risk tidal turbine design: large differences are observed both in terms of the nature & magnitude of the resulting loads and the wave interaction with the surrounding flow field.

scholarly journals CFD Research on the Hydrodynamic Performance of Submarine Sailing near the Free Surface with Long-Crested Waves

2022 ◽  
Vol 10 (1) ◽  
pp. 90
Author(s):  
Kai Dong ◽  
Xianzhou Wang ◽  
Donglei Zhang ◽  
Liwei Liu ◽  
Dakui Feng
Keyword(s):  
Free Surface ◽  
High Frequency ◽  
Control Strategies ◽  
Response Spectrum ◽  
Hydrodynamic Performance ◽  
Irregular Waves ◽  
High Frequency Region ◽  
Irregular Wave ◽  
Grid Approach ◽  
Calm Water

The simulations of submarine sailing near the free surface with long-crested waves have been conducted in this study using an in-house viscous URANS solver with an overset grid approach. First, the verification and validation procedures were performed to evaluate the reliability, with the results showing that the generation of irregular waves is adequately accurate and the results of total resistance are in good agreement with EFD. Next, three different submerged depths ranging from 1.1D to 3.3D were selected and the corresponding conditions of submarine sailing near calm water were simulated, the results of which were then compared with each other to investigate the influence of irregular waves and submerged depths. The simulations of the model near calm water at different submerged depths demonstrated that the free surface will cause increasing resistance, lift, and bow-up moments of the model, and this influence decreases dramatically with greater submerged depths. The results of the irregular wave simulations showed that irregular waves cause considerable fluctuations of hydrodynamic force and moments, and that this influence remains even at a deeper submerged depth, which can complicate the control strategies of the submarine. The response spectrum of hydrodynamic forces and moments showed slight amplitudes in the high-frequency region, and the model showed less sensitivity to high-frequency excitations.

Comparison of Control Methods of Permanent Magnet Synchronous Motor in Electric Vehicle

2014 ◽  
Vol 556-562 ◽  
pp. 1396-1399 ◽  
Author(s):  
Zhao Gang ◽  
Hong Jie Wang
Keyword(s):  
Vector Control ◽  
Permanent Magnet ◽  
High Performance ◽  
Control Method ◽  
Control Strategies ◽  
Permanent Magnet Synchronous Motor ◽  
Direct Torque Control ◽  
Synchronous Motor ◽  
Torque Control ◽  
Control Mode

At present, the pure electric vehicles with a permanent magnet synchronous motor (PMSM) vector control (VC) and direct torque control (DTC) are mainly control method. These two kinds of control mode are considered as a high performance PMSM control strategy which has been widely used in practice [5]. Starting from the mathematical model of PMSM, two kinds of control strategies are to be the theoretical analysis, so that the control thoughts and the composition of control system has a profound understanding to applies two kinds of strategies to control of PMSM. Simulink modeling and simulation results proved that vector control is better than that of direct torque.

scholarly journals Analysis of the effects of control strategies and wave climates on the loading and performance of a laboratory scale horizontal axis tidal turbine

2020 ◽  
Vol 212 ◽  
pp. 107713 ◽  
Author(s):  
Rodrigo Martinez ◽  
Stephanie Ordonez-Sanchez ◽  
Matthew Allmark ◽  
Catherine Lloyd ◽  
Tim O’Doherty ◽  
...  
Keyword(s):  
Control Strategies ◽  
Horizontal Axis ◽  
Laboratory Scale ◽  
Tidal Turbine ◽  
And Performance

scholarly journals Study on the Resonant Behaviors of a Bottom-Hinged Oscillating Wave Surge Converter

2021 ◽  
Vol 10 (1) ◽  
pp. 2
Author(s):  
Yao Liu ◽  
Yong-Hwan Cho ◽  
Norimi Mizutani ◽  
Tomoaki Nakamura
Keyword(s):  
Maximum Velocity ◽  
Irregular Waves ◽  
Width Ratio ◽  
Wave Surface ◽  
Regular Waves ◽  
Peak Period ◽  
Natural Period ◽  
Irregular Wave ◽  
Cfd Method ◽  
The Time Domain

This paper studied the resonant behaviors of a bottom-hinged oscillating wave surge converter (OWSC) as well as the relationship of resonance with the response and capture width ratio (CWR). The time-domain dynamic equation of an OWSC in shallow water based on the boundary element method (BEM) was solved by a Python code, considering the corrected wave surface and the nonlinearities of restoring moment, drag, and friction. The unknown factors, such as wave surface corrected factor and drag coefficient, were effectively calibrated with computational fluid dynamics (CFD) method. An intermediate initial angle in free decay is appropriate for use to determine the natural period. Under regular waves, the resonance occurs near the natural period for the uniform wave amplitude, rather than the uniform wave torque amplitude, and can disappear due to the amplification of Power Take-Off (PTO) friction. Under unit-amplitude regular waves, the period of maximum CWR is relatively close to the period of maximum velocity, but far from the resonant period. Under irregular waves, no stable resonance is observed because the maximum equivalent pitch angle appears at different peak periods of wave spectra with the variation in PTO damping. When the period of a regular wave or the peak period of an irregular wave is close to the natural period, a phase hysteresis of velocity relative to wave torque always occurs.

Continuous Finite-Time Torque Control for Flexible Assistance Exoskeleton with Delay Variation Input

Robotica ◽  
2020 ◽  
pp. 1-26
Author(s):  
Tao Xue ◽  
ZiWei Wang ◽  
Tao Zhang ◽  
Ou Bai ◽  
Meng Zhang ◽  
...  
Keyword(s):  
Finite Time ◽  
Disturbance Rejection ◽  
High Performance ◽  
Control Strategies ◽  
Fractional Power ◽  
Critical Issue ◽  
Human Robot Interaction ◽  
Torque Control ◽  
Finite Time Stability ◽  
Control Scheme

SUMMARY Accurate torque control is a critical issue in the compliant human–robot interaction scenario, which is, however, challenging due to the ever-changing human intentions, input delay, and various disturbances. Even worse, the performances of existing control strategies are limited on account of the compromise between precision and stability. To this end, this paper presents a novel high-performance torque control scheme without compromise. In this scheme, a new nonlinear disturbance observer incorporated with equivalent control concept is proposed, where the faster convergence and stronger anti-noise capability can be obtained simultaneously. Meanwhile, a continuous fractional power control law is designed with an iteration method to address the matched/unmatched disturbance rejection and global finite-time convergence. Moreover, the finite-time stability proof and prescribed control performance are guaranteed using constructed Lyapunov function with adding power integrator technique. Both the simulation and experiments demonstrate enhanced control accuracy, faster convergence rate, perfect disturbance rejection capability, and stronger robustness of the proposed control scheme. Furthermore, the evaluated assistance effects present improved gait patterns and reduced muscle efforts during walking and upstair activity.

A Review of Control Strategies for Permanent Magnet Synchronous Motor Used in Electric Vehicles

2013 ◽  
Vol 321-324 ◽  
pp. 1679-1685
Author(s):  
Jun Li ◽  
Jia Jun Yu ◽  
Zhenxing Chen
Keyword(s):  
Permanent Magnet ◽  
Intelligent Control ◽  
Control Strategies ◽  
External Disturbance ◽  
Permanent Magnet Synchronous Motor ◽  
Control Variable ◽  
Direct Torque Control ◽  
Synchronous Motor ◽  
Theoretical Background ◽  
Torque Control

This paper mainly reviews the development of permanent magnet synchronous motor drive system. It presents several approaches of PMSM control strategies, including control strategies based on classical control, modern control and intelligent control. Theoretical background briefly describes the properties of these control techniques. Among these control strategies, vector control and direct torque control are considered as the mature methods for PMSM motors control currently. Advanced control strategies, with adaptive control, variable structure control and intelligent control included, improve the performance of PMSM in some respects, such as variations of plant parameters sensitivity, external disturbance and so on. It shows that the researches in this area are still a popular research topic. Finally, this paper prospected the foreground of the control strategies for PMSM.

Numerical Study of Performance of Horizontal-Axis Tidal Turbine with Different Configurations

2021 ◽  
Author(s):  
Jisheng Zhang ◽  
Siyuan Liu ◽  
Yakun Guo ◽  
Dawei Guan ◽  
Ke Sun
Keyword(s):  
Numerical Study ◽  
Horizontal Axis ◽  
Tidal Turbine
Sign in / Sign up

Export Citation Format

Share Document