Search

Due to high probability of blade faults, bearing faults, sensor faults, and communication faults in pitch systems during the long-term operation of wind turbine components, and the complex operation environment which increases the uncertainty of fault types, this paper proposes a fault diagnosis method for wind turbine components based on an Improved Dung Beetle Optimization (IDBO) algorithm to optimize Support Vector Machine (SVM). Firstly, the Halton sequence is initially employed to populate the population, effectively mitigating the issue of local optima. Secondly, the subtraction averaging optimization strategy is introduced to accelerate the dung beetle algorithm in solving complex problems and improve its global optimization ability. Finally, incorporating smooth development variation helps improve data quality and the accuracy of the model. The experimental results indicate that the IDBO-optimized SVM (IDBO-SVM) achieves a 96.7% fault diagnosis rate for wind turbine components. With the proposed IDBO-SVM method, fault diagnosis of wind turbine components is more accurate and stable, and its practical application is excellent. [ABSTRACT FROM AUTHOR]

Renewable energies have a fundamental role in sustainability, with wind power being one of the most important due to its low production costs. Modern wind turbines are becoming bigger and more complex, and their operation and maintenance must be as optimized as possible. In this context, supervisory control and data acquisition systems provide valuable information, but there is no precise methodology for their analysis. To overcome this need, a generalized methodology is proposed to determine the recognition of critical subsystems through alarm analysis and management. The proposed methodology defines each subsystem in a precise way, shows the indicators for the alarms, and presents a theoretical framework for its application using the quantity and activation times of alarms, along with the real downtime. It also considers the transition of states when the wind turbine is operationally inactive. To highlight the proposal's novelty, the methodology is exemplified with a case study from the Southern Cone, applying the method through a data management and analysis tool. Four critical subsystems were found, with the alarms of wind vanes, anemometers, and emergency speeds being of relevance. The indicators and the graphical tools recommended helped guide the applied analysis. [ABSTRACT FROM AUTHOR]

Aiming at the problem that it is difficult to detect effective transient impact characteristics of wind turbine generator bearing fault signals due to non-stationary and strong noise, a fault diagnosis method based on adaptive redundant lifting wavelet dictionary and Bayesian biorthogonal sparse representation (SR) algorithm is proposed. First, a Bayesian model is integrated into the biorthogonal matching pursuit (MP) algorithm to improve the use of dictionary atoms in the effective support set. Then, an adaptive redundant lifting wavelet is used to construct a dictionary matching the transient characteristics of the signal. Finally, the SR algorithm is established by integrating the Bayesian biorthogonal MP model and adaptive redundant lifting wavelet dictionary. Simulation and experimental results show that the proposed method can improve the accuracy of signal reconstruction of transient components and effectively extract bearing fault features, thus verifying the effectiveness and robustness of the method. [ABSTRACT FROM AUTHOR]

This paper proposes a variable-power-tracking-operation-based frequency regulation scheme for a wind turbine generator (WTG) that employs a frequency-excursion-based control parameter to suppress frequency excursion under various wind speeds and disturbances. To this end, an improved system frequency response model is built, and then the frequency regulation characteristics of the WTG are investigated. The frequency-excursion-based control parameter is determined. Simulations based on the Matlab/Simulink simulator verify the effectiveness of the proposed variable-power-tracking-operation-based frequency regulation strategy. The simulation results clearly indicate that the suggested scheme is beneficial for reducing the maximum frequency deviation. The proposed frequency regulation scheme could enhance the networking capacity of wind farms and improve the capacity of the power grid to absorb renewable energy. [ABSTRACT FROM AUTHOR]

This paper presents a case study on condition monitoring of power generators at offshore wind turbines. Two fault detection models are proposed for detecting sudden changes in the sensed value of metallic debris at the generator. The first model uses an exponentially weighted moving average, while the second monitors first-order derivatives using a fixed threshold. This is expected to improve the maintenance activities by avoiding late or early part replacement. The economic impact of the proposed approach is also provided with a realistic depiction of the cost structure associated with the corresponding maintenance plan. While the specifics of the case study are supported by real-life data, considering the prevalence of the use of generators not only in offshore wind turbines but also in other production environments, we believe the case study covered in this paper can be used as a blueprint for similar studies in other applications. • Large scale condition monitoring demonstrates economic benefits. • Case study from real wind turbine population with economic impact assessment. • Sensor for monitoring fault mode results in lead time for maintenance planning. • Sensitivity analysis assesses results despite downtime and power price uncertainty. [ABSTRACT FROM AUTHOR]

Purpose: Particle dampers are dynamic vibration absorbers that can be attached or inserted into a vibrating structure for broadband vibration attenuation. The particle damping technique is widely used across various industries for vibration attenuation because of its conceptual simplicity, cost-effectiveness, and suitability for harsh environments (Gagnon et al. in J Sound Vib, 2019. https://doi.org/10.1016/j.jsv.2019.114865; Lu et al. in Struct Control Health Monit, 2018. https://doi.org/10.1002/stc.2058). However, designing a particle damper for real-world applications is significantly challenging primarily due to the interaction among the numerous parameters that influence the damping effectiveness of a particle damper. Therefore, this contribution aims to experimentally investigate the particle dampers performance in the context of their designs. Methods: We introduce three different design variants, namely thin-walled cavity (TWC), thin-walled cavity with additional sheets (TWC-AS), and ring cavity (RC). Different strategies are detailed and evaluated in the current paper. Following the comprehensive study of various design variants at the laboratory scale, several tests were conducted on a real-scale wind turbine generator, subjected to real-world loading conditions. Additionally, the effect of particle damper size and its location for the structure on vibration attenuation has been studied. Results: Based on the experimental investigation, all these variants are effective in reducing the vibration amplitude of a structure. Furthermore, it has been found that for practical applications, particularly in the case of large-scale mechanical structures such as wind turbines, it is advisable to combine the most successful variants to design a particle damper. This approach can achieve significant vibration attenuation, and also minimize the additional mass of the granular material compared to a conventional particle damper. Conclusion: The findings from our experimental studies offer valuable insight into the design of particle dampers for large-scale hollow mechanical structures. [ABSTRACT FROM AUTHOR]

As wind turbine generator systems become more common in the modern power grid, the question of how to adequately protect them from cyber criminals has become a major theme in the development of new control systems. As such, artificial intelligence (AI) and machine learning (ML) algorithms have become major contributors to preventing, detecting, and mitigating cyber-attacks in the power system. In their current state, wind turbine generator systems are woefully unprepared for a coordinated and sophisticated cyber attack. With the implementation of the internet-of-things (IoT) devices in the power control network, cyber risks have increased exponentially. The literature shows the impact analysis and exploring detection techniques for cyber attacks on the wind turbine generator systems; however, almost no work on the mitigation of the adverse effects of cyber attacks on the wind turbine control systems has been reported. To overcome these limitations, this paper proposes implementing an AI-based converter controller, i.e., a multi-agent deep deterministic policy gradient (DDPG) method that can mitigate any adverse effects that communication delays or bad data could have on a grid-connected doubly fed induction generator (DFIG)-based wind turbine generator or wind farm. The performance of the proposed DDPG controller has been compared with that of a variable proportional–integral (VPI) control-based mitigation method. The proposed technique has been simulated and validated utilizing the MATLAB/Simulink software, version R2023A, to demonstrate the effectiveness of the proposed method. Also, the performance of the proposed DDPG method is better than that of the VPI method in mitigating the adverse impacts of cyber attacks on wind generator systems, which is validated by the plots and the root mean square error table found in the results section. [ABSTRACT FROM AUTHOR]

Implementation of renewable energy sources (RESs) in power systems can reduce the dependence on fossil-fuel-based thermal power generation systems. At the same time, however, the system inertia decreases as synchronous generators decrease; this is crucial for maintaining the stability of the power system. Virtual inertia control (VIC) can regulate the output of an inverter-based resource (IBR) by increasing the inertia. For a wind turbine generator (WTG), output control factors such as pitch angle control and maximum power point tracking (MPPT) significantly affect the performance of the VIC. This paper theoretically clarifies that the pitch angle control contributes to improvements in the performance of the VIC and helps avoid a loss of operation of the WTG in frequency drop events by analyzing the movement of the operational point of the WTG based on the physical characteristic of the WTG and control characteristics of the pitch angle control and MPPT; an electromagnetic transient (EMT) simulation, performed to verify the analysis, is also presented. [ABSTRACT FROM AUTHOR]

This paper examines an inertial response control for wind turbines in order to provide the system inertia decreased by the integration of asynchronous variable renewable energy sources. Specifically, an application of the temporal power surge, a strategy by which the output of a wind turbine can be temporarily increased with releasing the kinetic energy stored in the rotating mass, was proposed to address significant frequency drops in a microgrid. Since the rotational speed of turbine has to be decreased by this approach, it is necessary to further reduce the wind power output to recover the rotational speed after the temporal power surge. This drawback may lead to a second frequency drop, and it is effective to intentionally increase the rotational speed beforehand to mitigate this negative effect. However, this measure causes output curtailment under normal operating conditions. Hence, a determination method of the rotational speed considering the output curtailment was proposed in this paper to facilitate frequency regulation through the temporal power surge. The proposed methods for adjusting rotational speed are evaluated and their effectiveness were verified through numerical simulations. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

As the penetration of renewable energy sources into a power system increases, the significance of precise short-term forecasts for wind power generation becomes paramount. However, the erratic and non-periodic nature of wind poses challenges in accurately predicting the output. This paper presents a comprehensive investigation into forecasting wind power generation for the following day, using three machine learning models: long short-term memory (LSTM), convolutional neural network-bidirectional LSTM (CNN-biLSTM), and light gradient boosting machine (LGBM). In addition, this paper proposes a method to improve the prediction performance of LGBM by separating data according to the distribution of features, and training and testing each separated dataset with a distinct model. This study includes a comparative analysis of the performance of the proposed models in predicting wind turbine output, offering valuable insights into their respective efficiencies. The results of this investigation were analyzed for two geographically distinct wind farms (Korea and the UK). The findings of this study are expected to facilitate the selection of efficient prediction models within the forecast accuracy auxiliary service market and assist grid operators in ensuring reliable power supply for the grid. [ABSTRACT FROM AUTHOR]

The shift towards RES introduces challenges related to power system stability due to the characteristics of inverter-based resources (IBRs) and the intermittent nature of renewable resources. This paper addresses these challenges by conducting comprehensive time and frequency simulations on the IEEE two-area benchmark power system with detailed type 4 wind turbine generators (WTGs), including turbines, generators, converters, filters, and controllers. The simulations analyse small-signal and transient stability, considering variations in active and reactive power, short-circuit events, and wind variations. Metrics such as rate of change of frequency (RoCoF), frequency nadir, percentage of frequency variation, and probability density function (PDF) are used to evaluate the system performance. The findings emphasise the importance of including detailed models of RES in stability analyses and demonstrate the impact of RES penetration on power system dynamics. This study contributes to a deeper understanding of RES integration challenges and provides insights for ensuring the reliable and secure operation of power systems in the presence of high levels of RES penetration. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Some coastal cities are sometimes exposed to floods, mainly caused by strong winds or earthquakes on the seafloor. This causes the water waves heading to the coastal cities to rise quickly, possibly destroying civilization. The proposed study will introduce an intelligent rubber balloon that automatically acts as a water repellent to absorb the momentum of water hammers from the sea. The proposed system has been energized by wind power energy. This enables the control of the bus voltage of the DC link. Sequential balloons could be arranged in such a matter to form a repel flood wall. Wind turbine generators could be used for charging the storage batteries. These batteries energize the smart control system and DC motors coupled with air pumps. These pumps are used to inflate the sequential air balloons. The theoretical models of the proposed system components have been simulated by MATLAB environment. Three DC motors are connected based on the master-salve mechanism, and the third is considered in standby mode. These motors are controlled by a model reference adaptive controller. The tracking speed between reference and measured speeds has been accomplished. Control of switching ON-OFF balloons using fuzzy logic control and classical control has been compared. After using several control scenarios for air pressure in balloons, it is observed that the best response is obtained using fuzzy logic control since it reduces the setting time and faster time response compared to the classical PID controller. Also, it was noticed that time response improved when using a PID controller instead of proportional or PD control scenarios, and the system dynamic response became acceptable. [ABSTRACT FROM AUTHOR]

The wind turbine generator participates in the primary frequency regulation of the power system by releasing kinetic energy from the rotor. It is necessary to ensure that the rotor speed and converter capacity are within the safe range during the frequency regulation process; otherwise, it will have serious negative effects on the frequency stability of the power system. As an important primary frequency regulation parameter, the dead zone affects the evaluation of the frequency regulation ability of WTG. Therefore, the influence of the dead zone should also be further considered. In order to evaluate the frequency regulation capability of wind turbine generators more comprehensively and accurately, this paper proposes an optimized method for the parameter of virtual synchronous control for wind turbine generators by considering the dead zone and physical constraint boundary of primary frequency regulation. After establishing the time domain expression by considering the frequency regulation dead zone, the real-time frequency regulation capacity of the wind turbine generator is quantified by considering the speed limit of the rotor and the capacity limit of the converter. Furthermore, the optimal value of the frequency regulation coefficient can be derived. Simulation results show that the proposed method can effectively reduce the frequency deviation and frequency change rate of the power system, which can also keep the response within the physical constraint boundary. Consequently, the proposed method can fully utilize the ability for frequency regulation of the wind power generation system and effectively improve the frequency stability of the power system. [ABSTRACT FROM AUTHOR]

The present paper discusses the modeling and analysis of a diesel–wind generating system capable enough to cater to the electrical power requirements of a small consumer group or society. Due to high variations of the load demand or due to changes in the wind speed, the frequency of the diesel–wind system will be highly disturbed, and hence to regulate the frequency and power deviations of the wind turbine system, an effective controller design is a necessary requirement, and therefore this paper proposes a novel controller design based on PID scheme. The parameters of this controller is effectively optimized through a new snake optimizer (SO) in an offline manner to minimize frequency and power deviations of an isolated diesel–wind system. The performance of SO-PID for the diesel–wind system is evaluated by considering the integral of time multiplied absolute error (ITAE), integral absolute error (IAE), and integral of time multiplied square error (ITSE). The results were calculated for a step change in load, step change in wind speed, load change at different instants of time with diverse magnitude, and for random load patterns, and they were compared with some of the recently published results under similar working conditions. In addition, the effect of an ultracapacitor (UC) and redox flow battery (RFB) on SO-PID was investigated for the considered system, and the application results demonstrated the advantages of our proposal over other studied designs. [ABSTRACT FROM AUTHOR]

Wind Turbine Generators (WTG) are being integrated into distribution systems on a large scale worldwide as part of a global effort to capture green energy. Wind turbine generator intermittency may be mitigated by Battery Energy Storage Systems (BESS), which have emerged as a viable option in recent years. To find the best position and capacity for wind power generation and BESS charging/discharging dispatches, a Red Fox Optimisation (RFO) algorithm is used while optimising the imbalanced distribution network's performance under technological restrictions. The charging or discharging criteria for this method is the average feeder load. The charging techniques for BESS using WTG and Sustainable Average Load (SAL) are evaluated in terms of the free-running mode of dispatch cycle. The suggested approach is tested on an IEEE-37 bus Unbalanced Radial Distribution Network (UDN). It has been shown that the suggested method enhances several performance objectives of the distribution system. [ABSTRACT FROM AUTHOR]

This paper investigates automatic generation control (AGC) of a realistic hybrid four-control area system with a distinct arrangement of thermal units, gas units and additional power generation. A proportional-integral-double derivative cascaded with proportional-integral (PIDD-PI) controller is employed as secondary controller in each control area for robust restructured AGC considering bilateral transactions and contract violations. The Harris Hawks algorithm is used to determine the optimal controller gains and system parameters under several scenarios. Electric vehicle (EV) aggregators are employed in each area to participate fully along with thermal and gas units to compensate for the unscheduled system demand in the local area. A comparison of non-cascaded controllers such as PI-PD, PD-PID and the proposed PIDD-PI proves the superiority of the last. The effect of the decline in inertia is closely examined because of the sudden outage of a generating unit while at the same time considering the change in area frequency response characteristics and area control error. EV fleets make significant contributions to improving the system dynamics during system inertia loss. The use of EVs in the presence of a wind energy-supported grid can provide a stable efficacy to the power grid. Numerous simulations with higher load demands, stochastic communication delays in presence of the WTG plant, and violations in system loadings and changes in gas turbine time constants in the absence of WTG demonstrate the robustness of the proposed control approach. [ABSTRACT FROM AUTHOR]

We present key design parameters of an innovative 10 MW low-speed direct-drive superconducting generator by high-temperature superconductor coated conductors for the rotor windings. In the simulations, the generator has an iron rotor with the superconducting coils operating at 20 K while the rotor core and the cooper stator are at room temperature. The calculations have been performed by Finite Element Software Comsol Multiphysics. Electromagnetic design parameters, magnetic flux distributions, phase current, voltage, and loss distributions of the superconducting generator are introduced. In addition, the AC losses that arise during the current increase in the superconducting rotor were calculated separately using both the H- and AV-formulation forms of Maxwell's equations employing the non-linear current–voltage relation of the superconductor. The current distribution and magnetic field distribution of the superconductor coils, volumetric loss density distribution, and comparison of the losses of each coil layer have been analyzed and discussed in detail. [ABSTRACT FROM AUTHOR]

Steadily increasing rated unit power of direct-drive wind turbine generators for offshore applications requires solutions with high torque density. HTS excitation windings allow for a higher electromagnetic utilisation compared to an excitation by rare-earth permanent magnets but must be competitive regarding overall cost. This work addresses this multi-objective optimisation problem (mass, cost) by means of a numerical evaluation for a generator design with conventional iron parts and HTS excitation winding under variation of eight variables. The Pareto frontier is approximated for HTS excited direct-drive generators in the 7 MW power class. [ABSTRACT FROM AUTHOR]

The development of 10 MW class large-scale wind power systems has been the mainstream trend in the renewable energy field. An electrical design approach and an optimization method of the basic parameters for the different types of 10 MW wind turbine generators have been presented in our previous work. In this paper, the influence of the rated revolution on the weights of the generator and the high-temperature superconducting (HTS) field part are first studied for the HTS generators with stator outer diameters of 14, 7.4, and 4.1 m. The optimum value of the rated revolution is then determined and analyzed. In addition, the influence of the rated revolution on the generator performance is evaluated for the PM with stator outer diameters of 14.3, 7.3, and 4 m and copper generators with stator outer diameters of 13.9, 7.2, and 4.1 m. Finally, the generator characteristics with respond to the rated revolutions are compared for the three types of wind turbine generators with stator outer diameters of 14, 7, and 4 m. The results show that the HTS generators with stator outer diameter of approximately 14 m have a great advantage in practical applications corresponding to the desirably rated revolution of 40 min−1. [ABSTRACT FROM AUTHOR]

In this paper, a detailed model and an average model of an MMC (Modular Multilevel Converter)-controlled Permanent Magnet Synchronous Generator (PMSG)-based direct drive wind turbine are proposed. The models are used to analyze the steady-state and transient characteristics of the grid connectivity study of the wind turbine generator. Configuration of the electrical topology and the control scheme of the wind turbine generator for both models are comprehensively presented. In the detailed model, the MMC circuit is represented by power electronic IGBTs, with switching phenomena considered. Meanwhile, in the average model, the MMC circuit is simplified by using voltage source representation, hence the complexity of the MMC circuit and the simulation duration of the analysis can be reduced. Comparative analysis between the detailed and the simplified models is also investigated through simulation performed using PSCAD/EMTDC. The simulation results show that both models have a good controllability and dynamic stability under steady-state and transient conditions. The simulation results also confirm that the average model has adequate accuracy, and simulation time can be reduced significantly. [ABSTRACT FROM AUTHOR]

The wind power industry suffers from unexpectedly high failure rates in wind turbine high-speed shaft bearings (HSSBs). To reduce cost and improve availability, the industry needs an accurate fault prognostic and remaining useful life (RUL) capability. A reliable prognostic allows maintainers to better define when maintenance can be performed, improving availability or allowing for opportunistic maintenance. Wind turbines operate under harsh conditions and condition monitoring data shows the environment to be both non stationary behavior with high noise. This paper proposes a practical and effective data-driven methodology that can be applied for RUL prediction of HSSBs. A new health indicator (HI) is constructed based on the entropy measure of the so called "spectral shape factor" (SSF), after strengthening the original signal by Teager energy operator (TEO). An Elman neural network (ENN) is used for RUL estimation. Furthermore, prediction intervals of the RUL estimates are computed based on the trained ENN model in order to quantify the errors associated with the prediction. The methodology is validated using a real word data collected form 2 MW Suzlon S88 wind turbine. • A spectral shape factor (SSF) approach is developed for feature extraction. • SSF derived time-domain features give better degradation trending. • Critical value was determined for scaling the bearing health. • RUL prediction of high-speed shaft bearing based on Elman neural network. • Prediction interval of RUL estimates are computed based on trained ENN model. [ABSTRACT FROM AUTHOR]

Wind turbine generators (WTG) are expected to provide active power control (APC) to track active power instructions from the power grid or wind farm operators. Because the regulation of turbines’ mechanical dynamics strongly depends on pitch angle regulation, mitigating frequent pitch adjustments is a key issue, and accordingly, several rotor speed variation-first APC methods have been proposed to decrease pitch servo fatigue. However, due to the lack of a quantitative description on the utilization of rotor speed variation (RSV), the ability of reducing pitch action through RSV can hardly be analyzed and compared among the existing APC methods. Hence, the disturbance range of nonpitch regulation (DRNP) and the maximum DRNP are defined in this paper. The former represents the effect of pitch action mitigation through RSV with a specific APC strategy and provides a unified foundation for quantitatively evaluating and selecting APC methods from the perspective of pitch servo serviceability. The latter, which depends on the turbine specifications and is independent of the control method, represents the maximum effect that can be achieved for a WTG. On this basis, an improved APC method is proposed to further reduce pitch servo fatigue. Finally, the DRNP indicators and the effectiveness and feasibility of the proposed method are verified by the wind turbine simulator-based experiments. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In Tamil Nadu, India, the old wind turbines installed in 1988 have to be repowered and replaced by modern/advanced technological wind turbines. A solar power plant can be set up using the vast area between the wind turbines on the farm. The economic evaluation must be carried out to determine whether this hybrid project is economically beneficial. This article aims to examine the financial viability of repowering old wind turbines with solar power plants' inclusion. According to the initial investment costs specified within fixed areas and the distance between turbines, the issue is articulated as optimizing the net present value (NPV) of the project. In this study, the economic investigation on the wind farm located in Kayathar was explored by replacing 30 numbers of 200 kW old wind turbines with modern wind turbines of 2000–3000 kW and installing the solar power plant between wind turbines, excluding the shadow region of wind turbines. The HOMER Pro software and Excel spreadsheet were used to analyze the optimal allocation, economic, electricity production, and sensitivity analyses of the effective hybrid systems. The value of electricity prices was measured using the levelized cost of energy and NPV methods. Additionally, a sensitivity analysis of the chosen parameters for the internal rate of return and debt service coverage ratio was estimated for wind and solar hybridization. The economic analysis suggests satisfactory profitability for the project, even without depending on subsidies. Furthermore, sensitivity analysis helps one see the consequences of the risk on the life of the wind farm and its impact on the project's productivity and performance. [ABSTRACT FROM AUTHOR]

Inverter-based resources respond differently than synchronous generation sources during power system faults, challenging line protection reliability. Part I of this paper presented cases that challenge line protection schemes. In this paper (Part II), we provide solutions that can be applied to gain a substantial improvement in reliability. [ABSTRACT FROM AUTHOR]

Mechanical faults in wind turbine generators lead to a huge problems of breaking electricity production, increase the maintenance cost and can damage the wind turbine generator, which caught fire in the nacelle. Gearbox installed in the nacelle is the important component in wind turbine, it composed by shafts bearings and gearings. Always bearings and gearings failures are related together. Therefore, to control these rotating components we need to analysis their vibration signature. This work was done with Tunisian Electricity and Gas Company (STEG) it's about mechanical failures diagnostics which are based on three temporal vibration signals which are made by three sensors installed also in three positions axial, vertical, and horizontal. In this work we present a Fast Fourier Transform which is applied on raw mechanical vibration signals by the vibration department of STEG, which are compared with a new strategy of envelope analysis is commonly used to obtain the mechanical faults harmonics from the envelope signal spectrum analysis and has shown a more suitable results of diagnostics which is applied on the same data sets from Fast Fourier Transform. In this work, we illustrate a squared envelope based on spectral kurtosis approach to determine optimum envelope analysis parameters including the filtering band and center frequency through a short time Fourier transform. This method proves a better diagnosis results using real vibration data set from vibration department of STEG. [ABSTRACT FROM AUTHOR]

This article develops a novel nonlinear controller for the mitigation of drivetrain torsional oscillations of wind turbine generators following large disturbances. The key idea is to integrate differential geometry theory with an extended state observer. Differential geometry allows transforming the wind turbine generator nonlinear model into a simple second-order Brunovsky system, whereas the extended state observer can accurately estimate the states of the transformed Brunovsky system and compensate unknown disturbances. Simulation results show that, under various conditions in different test systems, the proposed controller achieves significant enhancements with respect to conventional approximate linearization-based controller and nonlinear sliding mode control-based method. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a deep learning aided constraint encoding method to tackle the frequency-constraint microgrid scheduling problem. The nonlinear function between system operating condition and frequency nadir is approximated by using a neural network, which admits an exact mixed-integer formulation (MIP). This formulation is then integrated with the scheduling problem to encode the frequency constraint. With the stronger representation power of the neural network, the resulting commands can ensure adequate frequency response in a realistic setting in addition to islanding success. The proposed method is validated on a modified 33-node system. Successful islanding with a secure response is simulated under the scheduled commands using a detailed three-phase model in Simulink. The advantages of our model are particularly remarkable when the inertia emulation functions from wind turbine generators are considered. [ABSTRACT FROM AUTHOR]

The grid codes define low voltage ride-through (LVRT) as capability of wind turbine generator (WTG) to support the grid voltage by injecting reactive power and suppress the rise of DC-link voltage and inrush rotor current in the rotor side converter (RSC) of the doubly fed induction generator (DFIG) during a fault. Moreover, the rotor current increases significantly during severe disturbances if any protection schemes are not employed. Therefore, the protection schemes must be used to avoid the damage to the converter during a fault. This paper proposes an enhanced LVRT control scheme of a DFIG employing a crowbar in the RSC side and braking chopper across the DC-link capacitor. The DFIG is highly delicate to grid voltage fluctuation during a fault because the DFIG is directly linked to the grid via stator. During severe fault the crowbar regulates the rotor current within an acceptable range and the braking chopper discharges the DC-link capacitor via resistor within a safe limit. The proposed LVRT control scheme is performed for a 2.4-MW DFIG using a MATLAB/SIMULINK simulator. The results delineate that the proposed control scheme is able to rapidly decrease the rotor current and repress the escalation in DC-link voltage during a grid fault. [ABSTRACT FROM AUTHOR]

The universal power demand is increasing every day because of population growth, industrial revolution and high standards of living. The renewable energy technologies (RETs) are environmental and cost‐effective solutions to satisfy dynamic load profile based on the application of multiple components of a standalone microgrid system that encompasses photovoltaic (PV), diesel generator (DG), electric storage system and wind turbine generator (WTG). This study reveals more insight into various research questions that have not been completely addressed in past investigations. The contributions of the study are expressed: (i) analyse the effects of RETs on the total cost, (ii) test the total benefits, (iii) estimate the market benefit share of the unit that reflects the benefit of one generation unit in proportion to the whole power system, (iv) maximise and minimise the yearly average power generated by (PV and WTG) and DG. This research work presents the application of fmincon optimising tool to accomplish the objectives of the study owing to some significant characteristics. The outcomes of the work show the validity of the model and can assist the utilities to minimise the costs that are identified with the optimal operation of their power systems. [ABSTRACT FROM AUTHOR]

Using inverter-based topologies and lack of rotational masses can lead to a noticeable reduction in the inertia of modern systems and have detrimental effects on the resiliency, stability and strengths of microgrids. Effective frequency control ancillary services and modern adaptive control mechanisms can be proposed to resolve the mentioned challenges practically. From this perspective, several flexible and intelligent control approaches have been recently introduced to create a balance between generation and load demand during various operational conditions in low-inertia power systems. This study suggests a supportive collaboration between two distributed generations including virtual inertia of wind turbine generator and fast speed micro-turbine based on an adaptive optimal model predictive control (AOMPC). To demonstrate the effectiveness of the proposed framework, the results are compared with the previous controllers like optimal proportional–integral, optimal fractional order proportional–integral–derivative (PID), optimal fuzzy PID, the optimised membership function of fuzzy and adaptive MPC controller during multiple load variations, changes in the weather patterns, unwanted time-varying uncertainties and collapse of power generation units. [ABSTRACT FROM AUTHOR]

In this article, we propose a variable voltage control strategy for parallel connected hybrid generators (HGs) in a medium-voltage dc (MVdc) array grid. In the presented scheme, the outputs of HGs are rectified and interfaced to an offshore MVdc array grid. The MVdc grid, whose voltage is varied but controlled, connects the wind turbines in the farm to an offshore substation. Using dc–dc converters, the voltage is stepped up at the offshore substation and sent to a terrestrial grid via undersea high-voltage dc (HVdc) export cables. The MVdc voltage is varied in a prescribed control strategy, whereas the HVdc voltage is maintained fixed at all times. The HG in the scheme presented in this article utilizes two rotor elements, a permanent-magnet rotor with fixed excitation and a wound field (WF) rotor with controllable excitation. The proposed control strategy includes a WF control scheme local to the HGs coordinated with a wind farm supervisory control system (SCS). A simulation platform is developed to evaluate the effectiveness of the control strategy in a large wind farm. Simulation results are validated on a laboratory prototype HG system showing a good agreement. [ABSTRACT FROM AUTHOR]

Due to high power density of the transverse flux permanent magnet machines (TFPMs), they are potential candidates for direct drive wind turbine (DDWT) applications. But the TFPMs usually suffer from high values of cogging torque and torque ripple which are troublesome in DDWTs. Aiming to improve conventional TFPM torque profile, using Halbach-array of PMs is proposed. To select the optimum array, sensitivity analysis is carried out and the optimum array type is selected considering the machine performance and manufacturing feasibility. In order to minimize the cogging torque and achieve the maximum available power density, Design of Experiments (DOE) optimization method is carried on the stator-side parameters. The final design is prototyped and tested where the experimental results are compared with the conventional TFPM and the simulation results. The results indicate that by using the proposed transverse flux Halbach-array PM generator the cogging torque drops dramatically without deteriorating the machine average torque. [ABSTRACT FROM AUTHOR]

The article presents a full-size pole pair set-up of an MW-class direct drive (DD) high temperature superconducting (HTS) wind turbine generator. The set-up serves as a precursor to the world's first full-scale DD HTS generator developed within the EU-funded EcoSwing project. The set-up built for de-risking employs an HTS field winding in the rotor and a conventional copper armature winding in the stator, representing a minimum independent unit of the corresponding full generator. Such a prototyping approach well reflects the performance of the full generator at a low cost. The article first explains the main design considerations of the full generator, followed by designing and construction details of the set-up. Afterward, a number of tests for determining the key performance of the set-up are reported. The testing results showed that the HTS field winding ran stably at its rated current of 480 A and was well maintained below 30 K. Moreover, the tangential force in the set-up reached 29.8 kN, projecting the 2 MW target output power of the full generator. The set-up developed effectively validated the design ideas and engineering feasibilities of the full generator, leading to successful kick-off of the EcoSwing project. [ABSTRACT FROM AUTHOR]

The EU-funded EcoSwing project addresses the world's first full-scale direct-drive (DD) high temperature superconducting (HTS) wind turbine generator. Before the generator was installed on a commercial wind turbine, the generator had been tested on the ground at the Dynamic Nacelle Testing Laboratory (DyNaLab) in Fraunhofer Institute for Wind Energy Systems (IWES), serving as an experimental validation of the generator design. This article is centered on the ground testing of the EcoSwing HTS generator, which includes corresponding tests for validating the generator's cryogenic design and electromagnetic performance. Despite one HTS coil with a defect limiting the operating current significantly, partial power production up to 1 MW at 14.5 rpm was reached. The critical auxiliary systems, i.e., vacuum system and rotary helium coupling, behaved as expected or even better than anticipated. The work reported in the article successfully validates the generator design, and also provides firsthand information prior to installing and testing the HTS generator on the wind turbine. [ABSTRACT FROM AUTHOR]

Wind turbine generators (WTG) can participate in system frequency regulation via virtual inertial controllers (VIC). In the presence of frequency disturbances, VIC temporarily regulates the WTG power output forcing it to release/absorb kinetic energy into/from the grid. With increasing penetration of WTGs in power systems, grid operators require these generators to provide frequency regulation services; however, kinetic energy release/absorption can destabilize WTGs. Hence, to address these issues, a new large-perturbation nonlinear WTG model is proposed in this paper, based on the WTG internal response that is used to tune typical VICs. Novel worst case and optimal VIC tuning approaches are also proposed and discussed based on the developed WTG nonlinear model. Several simulations are presented to test and validate the proposed model and VIC tuning techniques, demonstrating their adequate performance and advantages. [ABSTRACT FROM AUTHOR]

Recently, sub- and super-synchronous oscillation (SSO) associated with converter-based wind turbine generators (WTGs) has been attracting wide attentions. To investigate such SSO incidents, impedance or admittance-based modeling and analysis were widely used. It was discovered that coupling effects exist between impedances or admittances at complementary (i.e., sub and super-synchronous) frequencies. However, there is a lack of experimental validation on the coupling effects of different WTGs. In this paper, the frequency-coupling admittance models (FCAMs) of two types of widely adopted WTGs, i.e., direct-drive and doubly-fed WTGs, are presented at first. Secondly, a perturbation based identification method is proposed to obtain the FCAMs. Next, the method is implemented in a control-hardware-in-the-loop (CHIL) platform based on RTDS. Then with extensive CHIL tests, the FCAMs of both types of WTGs are obtained, and the impacts of frequency-coupling effects on SSO are validated. Finally, the characteristics of frequency-coupling effects and the root causes are further examined. This study is of important reference value to select appropriate models for oscillatory stability analysis. [ABSTRACT FROM AUTHOR]

High temperature superconducting (HTS) technologies are expected to be a key enabler for lightweight and cost-effective direct-drive (DD) trains for large wind turbines. This paper reports the designing and basic experimental validation of the world's first full-scale DD HTS generator demonstrated on a commercial wind turbine. The HTS generator has its rotor with an HTS field winding working below 30 K, which is achieved by using off-the-shelf Gifford-McMahon cryocoolers. The stator of the generator is essentially conventional, except that the armature winding has four segments to limit fault torques in case of sudden short circuits due to converter failures. Compared to an existing DD permanent magnet generator on the turbine, the air gap shearing stress of the HTS generator is doubled, and the weight is reduced by 24%. The overall design requirements from the turbine integration perspective, as well as the topological considerations, are first described in this paper. The electromagnetic and cryogenic designs are then presented, followed by performance testing of HTS coils. The basic experimental validation shows that the cryogenic design is satisfactory and the measured no-load voltage matches the finite element calculation very well. [ABSTRACT FROM AUTHOR]

In order to meet the power prerequisites of their citizens, many countries are heavily dependent on the utilization of fossil fuels for power generation. This has reduced the natural reserve of fossil fuels and caused a large percentage of greenhouse gas emissions (GHGs). It is imperative to harness energy from renewable energy resources (RERs) as a measure to supplement the authors’ daily energy needs from the conventional units. The proposed microgrid system deals with the incorporation of the wind turbine generator (WTG), diesel generator, hydro turbine, photovoltaic and battery storage system for optimisation of net present cost (NPC), annualised cost of the system (ACS), GHG, fuel cost, operating costs and cost of energy (COE) by using hybrid optimisation model for electric renewables using HOMER software. The system is designed with the energy demand of 618 kWh/day at a peak load of 72.5 kW. The values of NPC, COE, ACS and fuel consumption obtained in the optimised configuration are $942,654/yr, $ 127,415, $0.327/kWh and 51,236 L/yr. The simulation results obtained from the optimised scenario reveal that the utilisation of RERs has been found to be a cost effective means to supply remote areas.

Wind energy technology is developing more and more from recent decades in many countries. Therefore, addressing the latest wind turbine research issues, this study develops a dynamic model of a permanent magnet synchronous generator and an active rectifier—as part of a unified dynamic model of a wind turbine generator in MATLAB/Simulink. In addition, a novel technique for the verification of the open-loop and the closed-loop transfer functions in the frequency domain is presented. The technique develops by analysing the frequency responses of the transfer function at various frequencies. Furthermore, the cascaded control loops of the developed model are designed and the stability of the designed controllers is tested in response to step changes in reference values.

Innovations which help facilitate predictive maintenance strategies have the potential to greatly reduce costs associated with wind turbine O&M by driving efficiency and increasing wind turbine availability. This study uses multiple examples of the same generator bearing failure to provide insight into how condition monitoring systems can be used in to train machine learning algorithms with the ultimate goal of predicting failure and remaining useful life. Results show that by analysing high-frequency vibration data and extracting key features to train support vector machine algorithms, an accuracy of 67% can be achieved in successfully predicting failure 1–2 months before occurrence. This study reflects on the limitations surrounding a generalised training approach, taking advantage of all available data, showing that if too many different examples are considered of different wind turbines and operating conditions, the overall accuracy can be diminished.

This paper discusses the design of supervisory control on the wind turbine generator system operated in Region II. There are two objective controls here, namely maximizing the power extraction and accommodating the minor fault on control components (sensor and actuator). This control system then is called as Supervisory Fault Tolerant Control (SFTC) which is consisted of supervisory level and regulatory control. For the first objective, the supervisory level applies an extremum seeking (ES) algorithm to adjust the reference generator speed to be an optimum value correlated with the maximum generator output power. Here the proportional - integral (PI) controller as the regulatory controller is applied to make the wind turbine generator system tracking the reference speed. For the second objective, the supervisory level uses an extended observer in order to provide fault estimation used in the compensation mechanism. The compensation mechanism is conducted in the measurement signal (as an input of the controller) and in the output of the controller in order to accommodate sensor fault and actuator fault respectively. The simulation results prove that ES-based SFTC yields the power output much larger and more steady than reference formula-based SFTC, and SFTC can tolerate the minor faults in sensor and actuator well. [ABSTRACT FROM AUTHOR]

This paper proposes a comprehensive MPPT method by which extraction of maximum power from wind turbine and its subsequent transfer through various power stages and final delivery to the connected grid are realized. In the proposed system, the operation of the wind turbine at its maximum efficiency point is maintained by control of grid‐tied inverter such that the shaft speed of the generator is set to result the desired optimum tip speed ratio of the turbine. The proposed comprehensive MPPT estimates the required DC link voltage for each wind speed using a unified system model, uses a loss factor to account for the system losses, and then controls the inverter to push the WT extracted maximum power into the grid. The comprehensive MPPT is developed and is validated in MATLAB/Simulink platform in a wide range of operating wind speed. The results ascertain that the wind turbine is made to operate at its maximum efficiency point for all wind speeds below the rated one. [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With increased wind power penetration in modern power systems, wind turbine generators (WTG) are expected to provide the active power control (APC) for tracking a desired power reference from system or wind farm operators. In practice, the pitch angle control (PAC) and the rotor speed control (RSC) methods can be used for APC in variable-speed variable-pitch WTGs, but the latter using turbine inertia as energy buffer is more attractive due to less pitch activation and higher wind energy production. For existing RSC methods, when the rotor speed reaches the upper speed limit at high wind speed or low power reference, they will actually become PAC to follow active power command, which also results in frequent pitch angle manipulation and considerable fatigue on the pitch servo system. To overcome this drawback, this paper proposes a new APC strategy integrating the rotor speed and pitch angle regulation. By utilizing the kinetic energy of rotor inertia at any pitch position (zero as well as non-zero pitch angle), this strategy can effectively avoid frequent action of pitch actuator while sustaining dispatched active power. The proposed method is verified by the fatigue, aerodynamics, structures, and turbulence-based simulations and wind turbine simulator-based experiments. [ABSTRACT FROM AUTHOR]

As a powerful power system simulation software package, PSS/E has great advantage in large-scale power system simulation. However, in the PSS/E dynamic model, there is no low voltage ride through (LVRT) the model for the wind turbine generator, and that is why for engineering practice it less referred with regard to wind power simulation. According to the analysis of the principle of the PSS/E second generation generic model wind generator, this paper built the LVRT a model-based PSS/E second generation generic model for the wind generator with the help of Fortran, and the model has been verified. The model this paper has built enriches the dynamic model of PSS/E and has led to more reference to PSS/E in engineering practice for the study of power system simulation with fluctuant wind power. [ABSTRACT FROM AUTHOR]