Reference Pitch Research Articles

Exploring the Potential of Hybrid Excitation Synchronous Generators in Wind Energy: A Comprehensive Analysis and Overview

Due to the unpredictable nature of the wind, uncertainty in the characteristics of wind electrical conversion systems (WECSs), and inefficient management tactics, wind turbines have historically had operational inefficiencies. In order to overcome these drawbacks, the hybrid excitation synchronous generator (HESG), an alternative to traditional generators, is presented in this study along with the suggestion to use robust regulators to regulate HESGs. This research begins with a thorough review of the literature on generators often seen in modern wind systems. Next, a simulation platform that merges a WECS with a HESG tied to an isolated load is built using the MATLAB Simulink environment. Pitch angle control investigation shows a new experimental approach to determine the link between turbine output and the reference pitch angle. Furthermore, an evaluation of the mechanical stability of the WECS is conducted by a comparison of the performance of a H∞ controller and a CRONE controller. The simulation results demonstrate the efficiency of the CRONE controller in reducing mechanical vibrations in the WECS. By reducing vibrations, the proposed control technique enhances the overall performance and efficiency of the wind turbine system. The field is extended by the demonstration of how HESGs and reliable control systems can enhance wind turbine performance while eliminating inherent limitations.

Controller design for a tidal turbine array, considering both power and loads aspects

The complex turbine-wake interactions within a tidal array leads to sub-optimal power generation from most tidal turbines, and results in higher fatigue loading on downstream turbines due to upstream turbines increase the turbulence intensity in the wake reaching other turbines. This paper presents an array controller which determines the power and loads set-points between the turbines based on incoming flow velocity for each turbine. This control methodology enables to dynamic response in time-variable flow velocity and trade-off between output power and fatigue loads through adjusting reference pitch angle and maximum power point tracking reference speed simultaneously for each turbine. The benefits of this novel control strategy is tested in a 4.5 MW three-turbine array model which is simulated in MATLAB/Simulink. Results show that in low flow velocity, the objective of stabilizing the fluctuation of loads is mainly achieved by adjusting generator speed. Conversely, the pitch controller dominates the results of the array in high flow velocity. Under the premise of mitigating fatigue loads, the proposed control strategy is still able to guarantee a high-level output power extraction.

Effects of wind field characteristics on pitch bearing reliability: a case study of 5 MW reference wind turbine at onshore and offshore sites

This paper presents a study on pitch bearing basic rating life affected by wind field characteristics at both onshore and offshore wind sites. The National Renewable Energy Laboratory 5 MW reference wind turbine is selected for the study. Wind field characteristics including reference hub height mean wind speed, wind speed distribution, wind shear, and vertical inflow are studied. A decoupled approach is employed where global analysis is performed first. Second, the load effects from the global analysis are applied on a reference pitch bearing designed based on best industrial practices. For the case study onshore site, it is found that the Kernel density estimation best fits the wind distribution, while the International Electrotechnical Commission proposed distribution appears to be not suitable. Moreover, it is shown that the seed number has high effect on the bearing life in turbulence wind and the wind speeds around rated have the highest contribution in both bearing fatigue damage and extreme load failure. The results contribute to better understanding of the wind field characteristics on the pitch bearing life.

Robust Adaptive Neural Cooperative Control for the USV-UAV Based on the LVS-LVA Guidance Principle

Around the cooperative path-following control for the underactuated surface vessel (USV) and the unmanned aerial vehicle (UAV), a logic virtual ship-logic virtual aircraft (LVS-LVA) guidance principle is developed to generate the reference heading signals for the USV-UAV system by using the “virtual ship” and the “virtual aircraft”, which is critical to establish an effective correlation between the USV and the UAV. Taking the steerable variables (the main engine speed and the rudder angle of the USV, and the rotor angular velocities of the UAV) as the control input, a robust adaptive neural cooperative control algorithm was designed by employing the dynamic surface control (DSC), radial basic function neural networks (RBF-NNs) and the event-triggered technique. In the proposed algorithm, the reference roll angle and pitch angle for the UAV can be calculated from the position control loop by virtue of the nonlinear decouple technique. In addition, the system uncertainties were approximated through the RBF-NNs and the transmission burden from the controller to the actuators was reduced for merits of the event-triggered technique. Thus, the derived control law is superior in terms of the concise form, low transmission burden and robustness. Furthermore, the tracking errors of the USV-UAV cooperative control system can converge to a small compact set through adjusting the designed control parameters appropriately, and it can be also guaranteed that all the signals are the semi-global uniformly ultimately bounded (SGUUB). Finally, the effectiveness of the proposed algorithm has been verified via numerical simulations in the presence of the time-varying disturbances.

Dynamic Performance Improvement of Pitch Angle Control Using PID and PIDA Controllers for Wind Generation Systems

Abstract Recently, wind energy is one of energy sources most have been devoted much awareness as result of shortage of energy. This study shows loads which are formed in the rotating shaft of wind turbine (WT). These loads cause disturbances on the blades, which leads to damage the blades. these loads can be exceeded, and the amount of productive energy can be controlled by using a good control unit that adjusts the angle of the WT blade. For the previous purpose, independent electric motor is used to control blade pitch, this process called pitch control (PC) system. This paper presents a mathematical model of PC system that is controlled by using two different controllers in MATLAB/Simulink; proportional -integral-derivative controller (PID) and proportional -integral-derivative-acceleration (PIDA). In this system three different function are used as reference pitch angle; unit step function, sinewave function and step change signal which are used on control system without any controller and it is found that output system isn’t reached to a reference value for three functions. The steady state error equal to 76% when step function is used, so the controller is needed for a system. When PID and PIDA controllers are used, the time domain specification of output is improved. The steady state error in PID and PIDA controllers is 9% and 0.014% respectively. It is found that the better time domain specification is given by PIDA. PID and PIDA controllers are tested with sinewave and step change, PIDA is also produced the best response.

Auditory aversion in absolute pitch possessors

Absolute pitch (AP) refers to the ability of identifying the pitch of a given tone without reliance on any reference pitch. The downside of possessing AP may be the experience of disturbance when exposed to out-of-tune tones. Here, we investigated this so-far unexplored phenomenon in AP, which we refer to as auditory aversion. Electroencephalography (EEG) was recorded in a sample of AP possessors and matched control musicians without AP while letting them perform a task underlying a so-called affective priming paradigm: Participants judged valenced pictures preceded by musical primes as quickly and accurately as possible. The primes were bimodal, presented as tones in combination with visual notations that either matched or mismatched the actually presented tone. Both samples performed better in judging unpleasant pictures over pleasant ones. In comparison with the control musicians, the AP possessors revealed a more profound discrepancy between the two valence conditions, and their EEG revealed later peaks at around 200 ms (P200) after prime onset. Their performance dropped when responding to pleasant pictures preceded by incongruent primes, especially when mistuned by one semitone. This interference was also reflected in an EEG deflection at around 400 ms (N400) after picture onset, preceding the behavior responses. These findings suggest that AP possessors process mistuned musical stimuli and pleasant pictures as affectively unrelated with each other, supporting an aversion towards out-of-tune tones in AP possessors. The longer prime-related P200 latencies exhibited by AP possessors suggest a delay in integrating musical stimuli, underlying an altered affinity towards pitch–label associations.

Design and implementation of an intelligent digital pitch controller for digital hydraulic pitch system hardware-in-the-loop simulator of wind turbine

ABSTRACT Digital hydraulics is a potential technology for the Hydraulic Pitch System (HPS) in Wind Turbine (WT). Digital Hydraulics Pitch System (DHPS) uses Digital Flow Control Units (DFCU) to develop the precise pitching action. In this paper, a novel Intelligent Digital Pitch Controller (IDPC) is proposed. The proposed controller is designed and implemented on a developed lab-scale DHPS Hardware-in-the-Loop (HIL) simulator. The various parameters of DHPS-hardware were designed using the bottom-up design methodology. The IDPC comprises Machine Learning (ML)-based WECS and DHPS controllers in the outer and inner loop respectively. HIL simulations were conducted with the implemented IDPC. The ML-based WECS controller predicts the reference pitch angle close to its desired value. The ML-based DHPS controller predicts the states of DFCU to develop real-time pitching action in DHPS-hardware. Several case studies were conducted to validate the effectiveness of the proposed IDPC. A study shows that IDPC controlled DHPS exhibits better performance than an ML-Proportional Integral (PI) controlled HPS with proportional flow control valve. Subsequently, the performance of the IDPC is compared with PI-ML cascade controller. This study shows that the Maximum Absolute Error (MAE) between the generator speed and its rated speed is 0.87% and 19.29% for the proposed controller and PI-ML cascade controller, respectively. Similarly, MAE (error between generator torque and its rated torque) of torque is 0.85% and 5.46% for the proposed controller and PI-ML cascade controller, respectively. Thus, the implementation of the IDPC develops optimal power with minimal speed/torque fluctuations.

Adaptive Robust Generalized Dynamic Inversion Quadrotor Control

Abstract This paper proposes a two loops control system structure for position and attitude of the Quadrotor flying vehicle. To control the Quadrotor’s center of gravity position in the instantaneous horizontal inertial planes, a small disturbance linearization-based Proportional-Derivative controller is employed in the outer (position) loop to provide reference pitch and roll tilting commands to the inner (attitude) loop. The outer loop also generates the thrust command required to track desired altitude trajectories. The inner loop utilizes a novel Adaptive Robust Generalized Dynamic Inversion (ARGDI) control design that is made by augmenting a direct adaptive control element in the baseline Robust Generalized Dynamic Inversion control system. The adaptive control law is obtained via a control Lyapunov function, and it aims to reduce the dependency of the control system on the geometric and inertia parameters of the Quadrotor in order to overcome control performance degradation due to modeling and parametric uncertainties, and due to external wind disturbances and dynamic scaling of the Moore-Penrose Generalized inverse. Computer simulations are performed in the Matlab/Simulink environment on a six DOFs Quadrotor model to demonstrate the robust globally asymptotically stable performance of the two loops control system. Additionally, performance of the inner ARGDI attitude control loop is tested on an experimental Quanser’s three DOFs Hover test bench.

Three‐dimensional trajectory tracking of an underactuated AUV based on fuzzy dynamic surface control

The three-dimensional trajectory tracking of an underactuated autonomous underwater vehicle (AUV) under the complex unknowns including model uncertainties and time-varying disturbances is studied. The reference pitch angle and yaw angle are designed in kinematics, based on the time-varying reference trajectory. Dynamics controllers are developed by incorporating the first-order filter into the dynamic surface control (DSC), which simplifies the design process and overcome differential explosion in the traditional backstepping. To reduce the influence of the complex unknowns, an adaptive fuzzy-based DSC scheme is employed to identify the lumped disturbances with arbitrary accuracy and further enhance system robustness. Lyapunov stability analysis demonstrates that tracking errors are bounded and converge to an arbitrarily small neighbourhood of zero. Finally, simulation studies and comparisons with DSC scheme are carried out to illustrate the effectiveness and superiority of the proposed scheme.

Auditory T-Complex Reveals Reduced Neural Activities in the Right Auditory Cortex in Musicians With Absolute Pitch.

Absolute pitch (AP) is the ability to identify the pitch names of arbitrary musical tones without being given a reference pitch. The acquisition of AP typically requires early musical training, the critical time window for which is similar to that for the acquisition of a first language. This study investigated the left–right asymmetry of the auditory cortical functions responsible for AP by focusing on the T-complex of auditory evoked potentials (AEPs), which shows morphological changes during the critical period for language acquisition. AEPs evoked by a pure-tone stimulus were recorded in high-AP musicians, low-AP musicians, and non-musicians (n = 19 each). A balanced non-cephalic electrode (BNE) reference was used to examine the left–right asymmetry of the N1a and N1c components of the T-complex. As a result, a left-dominant N1c was observed only in the high-AP musician group, indicating “AP negativity,” which has previously been described as an electrophysiological marker of AP. Notably, this hemispheric asymmetry was due to a diminution of the right N1c rather than enhancement of the left N1c. A left-dominant N1a was found in both musician groups, irrespective of AP. N1c and N1a exhibited no left–right asymmetry in non-musicians. Hence, music training and the acquisition of AP are both accompanied by a left-dominant hemispheric specialization of auditory cortical functions, as indexed by N1a and N1c, respectively, but the N1c asymmetry in AP possessors was due to reduced neural activities in the right hemisphere. The use of a BNE is recommended for evaluating these radially oriented components of the T-complex.

Effects of Pitch Source on Pitch-Matching and Intonation Accuracy of Collegiate Singers

In this study, we examined the effects of multiple reference pitch sources on collegiate singers’ accuracy in pitch-matching and intonation tasks. We also investigated which reference pitch source participants preferred and for what reasons. Participants ( N = 99) sang a two-measure excerpt of Joseph Dearest, Joseph Mine after listening to the starting pitch of A on a pitch pipe, the piano, a vocal hum, or a tuning fork in two conditions. For one tuning fork condition, participants’ starting pitch was an A, the same pitch as the tuning fork. For the other tuning fork condition, their starting pitch was a G, a different pitch than the tuning fork. We selected two pitches for analysis, each corresponding to the first syllable of the word Joseph. We then analyzed pitch deviation of the two target notes from the reference pitch in each condition. Participants were most accurate in response to the piano and least accurate in response to the tuning fork when their starting pitch was a G. Participants expressed preference for the piano (37.12%) as their pitch source, followed closely by the pitch pipe (33.33%).

Perception and Cognition in Absolute Pitch: Distinct yet Inseparable

Absolute pitch (AP) refers to the rare ability to effortlessly identify and/or produce the pitch of a sound without a reference pitch ([Deutsch, 2013][1]). Since AP has been proposed to constitute an ideal model for investigating the joint influences of genes and environment on the development of a

Tonal and textural influences on musical sight-reading.

Two experiments investigated the impact of two structural factors-musical tonality and musical texture-on pianists' ability to play by sight without prior preparation, known as musical sight-reading. Tonality refers to the cognitive organization of tones around a central reference pitch, whereas texture refers to the organization of music in terms of the simultaneous versus successive onsets of tones as well as the number of hands (unimanual versus bimanual) involved in performance. Both experiments demonstrated that tonality and texture influenced sight-reading. For tonality, both studies found that errors in performance increased for passages with lesser perceived psychological stability (i.e., minor and atonal passages) relative to greater perceivedstability (i.e., major passages). For texture, both studies found that errors in performance increased for passages that were more texturally complex, requiring two-handed versus one-handed performance, with some additional evidence that the relative simultaneity of note onsets (primarily simultaneous versus primarily successive) also influenced errors. These experiments are interpreted within a perception-action framework of music performance, highlighting influences of both top-down cognitive factors and bottom-up motoric processes on sight-reading behavior.

Development and experimental investigation of a Quadrotor’s robust generalized dynamic inversion control system

The development of a two-loops Quadrotor’s robust generalized dynamic inversion (RGDI)-based control system is presented. The outer (position) loop utilizes PD position control of the Quadrotor’s center of gravity (CG) in the three-dimensional inertial space, and it provides reference pitch and roll tilting angles commands to the inner loop, in addition to the thrust command that is required to track desired altitude trajectories. The inner (attitude) loop applies RGDI control of a prescribed asymptotically stable dynamics of tilting and attitude errors from reference-tilting and desired-attitude trajectories, and it provides the three required control torque values such that desired CG positions in instantaneous horizontal inertial planes and desired-attitude trajectories of the Quadrotor are tracked. The proposed closed loop system is shown to guarantee finite-time semi-global practically stable trajectory tracking. Numerical simulations of the proposed closed loop control system are performed on a six degrees of freedom Quadrotor’s mathematical model for nominal conditions and under parametric uncertainties and exogenous disturbances. Apart from numerical simulations, experimental tests are conducted on a three degrees of freedom Quadrotor test bench to assess performance of the RGDI control loop. Experimental results demonstrate improved tracking performance in comparison with classical Linear-Quadratic optimal control and conventional sliding mode control.

Generalized Cascaded Control Technology for a Twin-Rotor MIMO System with State Estimation

This article explores the design of a generalized feedback control operator coupled with state estimation for a twin-rotor MIMO system (TRMS) intended to regulate its predefined configurations (i.e., pitch and yaw) or follow time-varying reference configurations in a unified manner. Designing a generalized controller subject to the process and measurement uncertainties of a TRMS is a difficult task to undertake due to the coupling effects between its rigid body structure and the propeller dynamics associated with it. Many techniques have been proposed in the literature to control the output trajectory of a TRMS. However, they are either focused on addressing the regulator problem or do not take into account the process and measurement uncertainties in controlling the motion of the TRMS’s output (i.e., pitch and yaw). The proposed control technology mainly addresses the regulator problem of a TRMS in two cascaded phases. In the first phase, a nominal optimal feedback operator is obtained based on the reference output trajectory of a TRMS. The nominal operator is then used to determine the nominal state and input trajectories of a TRMS platform. In the second phase, the dynamics of a TRMS platform is linearized around its nominal trajectories. The linearized model is then used to find the optimal input signals for tracking/regulating the reference pitch and yaw angles of the TRMS platform subject to its process and measurement uncertainties. The proposed control law is also proven to be stable in the sense of Lyapunov. Theoretical results are validated through a set of computer simulations, and their performance is compared against a conventional proportional-integral-derivative scheme to demonstrate the superiority of the generalized cascaded control technology.

Autonomous Underwater Vehicles Attitude control using Neuro-Adaptive Generalized Dynamic Inversion

A novel two loops control architecture is presented for motion control of Autonomous Underwater Vehicle (AUVs). The outer (slow) positional loop incorporates classical Proportional-Derivative control to generate reference pitch and yaw tilting commands based on the positional errors. The reference attitude commands are fed to the inner (fast) attitude control loop, which utilizes Neuro-Adaptive Generalized Dynamic Inversion (NAGDI) control to generate the elevator and rudder deflections. The baseline Generalized Dynamic Inversion (GDI) control composed of particular and auxiliary parts. The particular part is designed by dynamically scaled generalized inversion of the attitude error dynamics, and the auxiliary part is constructed via a Lyapunov control function to provide global asymptotic stability to the angular body rate dynamics. A discontinuous control based on the concept of Sliding Mode Control (SMC) theory is augmented with baseline GDI. The modulation gain of discontinuous term is made adaptive to avoid chattering. Furthermore, online estimation of the unknown nonlinear attitude dynamics is achieved through radial basis function neural networks to obtain the resultant NAGDI control law. The proposed control law guarantees semi-global practically stable attitude tracking. Computer simulations are conducted on a six degrees of freedom simulator of the Monterey Bay Aquarium Research Institute AUV under nominal and perturbed marine environments.

Low-Altitude and High-Speed Terrain Tracking Method for Lightweight AUVs

This paper proposes a new method for cruising-type autonomous underwater vehicles (AUVs) to track rough seafloors at low altitudes while also maintaining a high surge velocity. Low altitudes are required for visual observation of the seafloor. The operation of AUVs at low altitudes and high surge velocities permits rapid seafloor imaging over a wide area. This method works without high-grade sensors, such as inertial navigation systems (INS), Doppler velocity logs (DVL), or multi-beam sonars, and it can be implemented in lightweight AUVs. The seafloor position is estimated based on a reflection intensity map defined on a vertical plane, using measurements from scanning sonar and basic sensors of depth, attitude, and surge velocity. Then, based on the potential method, a reference pitch angle is generated that allows the AUV to follow the seafloor at a constant altitude. This method was implemented in the AUV HATTORI, and a series of sea experiments were carried out to evaluate its performance. HATTORI (Highly Agile Terrain Tracker for Ocean Research and Investigation) is a lightweight and low-cost testbed designed for rapid and efficient imaging of rugged seafloors, such as those containing coral reefs. The vehicle succeeded in following a rocky terrain at an altitude of approximately 2 m with a surge velocity of approximately 0.8 m/s. This paper also presents the results of sea trials conducted at Ishigaki Island in 2017, where the vehicle succeeded in surveying the irregular, coral-covered seafloor.

Individual differences in absolute pitch performance: Contributions of working memory, musical expertise, and tonal language background

By definition, individuals with absolute pitch (AP) can categorize with near perfect accuracy without a reference pitch. This definition implies a uniformity of performance across people; however, in reality AP is a complex, multidimensional ability, shaped by both early and recent auditory experiences. In the present study we assess whether AP possessors' accuracy for identifying isolated notes is more distributed when judging more challenging instrumental timbres and octaves, as well as whether variability in note categorization could be explained through individual differences in musical expertise, language background, or working memory. In a standard test of AP, all participants performed virtually perfectly. When tested on the challenging notes, performance was more normally distributed. In exploratory analyses, we found (1) lower accuracy among participants who speak a tonal language, (2) less musical expertise among tonal language participants, and (3) a positive relationship between working memory and note performance among tonal language participants that was not present for non-tonal language participants. Taken together, these results highlight the complexity of AP categorization when considered as an auditory skill rather than a native talent. The observation that working memory may be an important in AP categorization under some challenging circumstances is consistent with recent theoretical accounts of how working memory and expertise relate to auditory recognition more broadly.

Vibration reduction strategy of offshore wind turbine under wind and wave loads

For purpose of studying the influence of wave on the wind turbines, the causes of aerodynamic load fluctuation and the aerodynamic torque ripple of hydrodynamic frequency is analysed in the mechanism by using the wave model. According to the formation mechanism, the existence of the ripples is verified on GH Bladed platform. To reduce the ripples caused by wind shear, tower shadow and waves of offshore wind turbine, a pitch control strategy is presented in this paper. Firstly, the integral gain of the top tower vibration acceleration signal is combined with the reference pitch angle value to reduce the uniform pitch. Then designing a low-pass filter to filter out the 3P output power ripple of the wind turbine, and converted into adjustment of individual pitch angles of three blades according to rotor azimuth, and superimposed with the changed uniform pitch angle at last. Simulation results indicate that the designed pitch control strategy can not only alleviate the 1P aerodynamic load ripple, but also suppress the aerodynamic torque and output power ripples at 3P and hydrodynamic frequency. The proposed pitch control strategy can reduce wind turbine fatigue loads and improve the output power quality.

Coordinated Control Strategies for a Permanent Magnet Synchronous Generator Based Wind Energy Conversion System

In this paper, a novel co-ordinated hybrid maximum power point tracking (MPPT)-pitch angle based on a radial basis function network (RBFN) is proposed for a variable speed variable pitch wind turbine. The proposed controller is used to maximise output power when the wind speed is low and optimise the power when the wind speed is high. The proposed controller provides robustness to the nonlinear characteristic of wind speed. It uses wind speed, generator speed, and generator power as input variables and utilises the duty cycle and the reference pitch angle as the output control variables. The duty cycle is used to control the converter so as to maximise the power output and the reference pitch angle is used to control the generator speed in order to control the generator output power in the above rated wind speed region. The effectiveness of the proposed controller was verified using MATLAB/Simulink software.