Large Wind Turbine Generators Research Articles

Study on Dynamic Response Characteristics of Circular Extended Foundation of Large Wind Turbine Generator

In order to study the dynamic response characteristics of circular extended foundation of wind turbine in mountainous areas, a 1:10 scaled model test was carried out on the circular extended foundation of 2MW wind turbine, and the deformation characteristics of wind turbine foundation under random wind load were analyzed by ABAQUS numerical calculation. The results show that: (1) The wind turbine foundation has different stress types on the windward side and the leeward side. The components of the windward side foundation are subjected to tensile stress, while the components of the wind turbine leeward side foundation are subjected to compressive stress. (2) The strain of the foundation bolt, the strain of the foundation ring, and the strain of the foundation plate are within the allowable range of material deformation, but the relative deformation of the windward side and the leeward side is quite different. (3) The numerical calculation results of wind turbine foundation under strong wind load are compared with the failure results of scale model experiment, which shows that the overall overturning failure of foundation is a dynamic response mode of wind turbine foundation. In the design and construction, it is necessary to strengthen the research on the windward side and the leeward side and strengthen the anti-overturning design of the wind turbine expansion foundation.

An Active Disturbance Rejection Control of Large Wind Turbine Pitch Angle Based on Extremum-Seeking Algorithm

This paper proposes the analysis and design of the linear active disturbance rejection controller (LADRC) for the pitch angle model of a large wind turbine generator (WTG). Since the transfer function of the pitch control system exhibits nonminimum-phase characteristics, the parameters of LADRC are difficult to tune using the conventional bandwidth method. On the basis of PI controller parameters to first-order LADRC parameters, an optimization problem is proposed in this paper to find the parameters of an LADRC for the pitch control system under the constraint of robustness measure, and the extremum-seeking (ES) algorithm is used to solve the problem. Simulation results show that LADRC can achieve better tracking and disturbance rejection performance than traditional PI control without loss of robustness against time delay.

A Mobile Robotic 3-D Measurement Method Based on Point Clouds Alignment for Large-Scale Complex Surfaces

Large-scale complex surfaces are the core components of large aircraft, ships, and wind turbine generators. High-accuracy manufacturing of the components is very crucial for its performance. Automated and high-accuracy large-scale 3-D measurement is an effective means for the manufacturing accuracy control of these components. This article proposes an automated mobile robotic profile measurement method for large-scale complex surfaces, and it also proposes a high-accuracy point clouds alignment algorithm to improve the measurement accuracy. A fringe projection scanner, integrated on the end of a mobile robot, is utilized to scan the surface and obtain the local scanning point clouds. The local scanning point clouds' coarse alignment is implemented using the robot's joint data and the laser sensor's positioning data. After that, a fine alignment algorithm combining the fruit fly optimization algorithm (FOA) with the improved iterative closest point (IICP) algorithm is proposed for point clouds' fine alignment. Practical measurement was performed on a sectional wind turbine blade, and a broad region of 4.6 m ×2.6 m was measured. An accuracy evaluation method based on point-to-plane distance was adopted to evaluate the measurement error. The result that the mean distance error is less than 0.4 mm shows the proposed mobile robotic measurement system and the aligning method are of high accuracy.

Alignment capabilities of big data’s value creation in the context of service delivery processes

PurposeWhile big data creates business value, knowledge on how value is created remains limited and research is needed to discover big data’s value mechanism. The purpose of this paper is to explore value creation capabilities of big data through an alignment perspective.Design/methodology/approachThe paper is based on a single case study of a service division of a large Danish wind turbine generator manufacturer based on 18 semi-structured interviews.FindingsA strategic alignment framework comprising human, information technology, organization, performance, process and strategic practices are used as a basis to identify 15 types of alignment capabilities and their inter-dependent variables fostering the value creation of big data. The alignment framework is accompanied by seven propositions to obtain alignment of big data in service processes.Research limitations/implicationsThe study demonstrates empirical anchoring of how alignment capabilities affect a company’s ability to create value from big data as identified in a service supply chain.Practical implicationsService supply chains and big data are complex matters. Therefore, understanding how alignment affects a company’s ability to create value of big data may help the company to overcome challenges of big data.Originality/valueThe study demonstrates how value from big data can be created following an alignment logic. By this, both critical and complementary alignment capabilities have been identified.

Performance comparison of 1X versus 4X HTS tapes toward the design a 10‐MW direct drive HTS generator for wind turbine applications

AbstractWith current developments underway at the University of Houston, 4× high‐temperature superconducting (HTS) yttrium barium copper oxide (YBCO) tapes are expected to reach a fourfold critical current density improvement at 30 K and 3 T as part of an Advanced Research Projects Agency‐Energy (ARPA‐E)‐sponsored project. The impetus for this project is to develop and deploy cost‐effective direct drive HTS generators for large offshore wind turbine generators. The improved conductor performance of 4× tapes over 1× tapes is projected to allow for a significant reduction in the amount of HTS tapes required to generate the excitation field and, thus, lead to a reduction of the overall generator cost. It was, however, deduced from simulation results that conventional methods of rotor field enhancement using rotor iron makes 1× conductor competitive enough compared with 4× conductors; hence, commercially available YBCO tapes can provide all the energy density requirements to make wind turbines a competitive energy resource based on energy forecasts. This paper is a presentation of design and optimization work to find the best generator topology from the point of view of both machine design and electricity supply. The generators are numerically modeled and simulated using 1× and 4× YBCO HTS conductors on either or of both the rotor and stator side of the generators.

A Rare-Earth Free Magnetically Geared Generator for Direct-Drive Wind Turbines

A novel Vernier type magnetically geared direct-drive generator for large wind turbines is introduced in this paper. Conventional Vernier-type machines and most of the direct-drive wind turbine generators use excessive amount of permanent magnet, which increases the overall cost and makes the manufacturing process challenging. In this paper, an electrically excited (PM_less) claw-pole type Vernier machine is presented. This new topology has the potential of reducing mass and cost of the generator, and can make the construction easy in manufacturing and handling. Analytical designs are verified using 3D finite-element simulations and several designs are evaluated to find the optimum design for a 7.5 MW, 12 rpm wind turbine application. It is shown, that the required torque can be achieved with an outer diameter of 7.5 m, and with a mass of 172 t (including the structural mass). The proposed generator is compared with commercial direct-drive generators, and it is found that the proposed generator has the highest torque density with 34.7 kNm/t.

Power System Reliability Evaluation Including Capacity Credit Considering Wind Energy with Energy Storage Systems in China

Abstract This paper is based on power system reliability evaluation on a power system. This research focuse on finding the best case of using large scale wind turbine generator (WTG) with multi-energy storage systems (multi-ESSs). By the way, calculate the capacity credit (C.C.) and effective load carrying capability (ELCC). In the future, renewable energy will occupy a large part of the electricity market. However, the reliability of power system can be influenced by the large scale WTG installed in the system. Multi-ESSs can be installed with the WTG used to decrease the fluctuation of power system reliability caused by the uncontrollable wind resource. The purpose of this paper is analyze the power system reliability in power system by the index of ELCC and C.C. by using multi-ESSs coordinated to the power system with renewable energy generators (REG). Monte Carlo simulation (MCS) method is employed to evaluation the reliability of power system with WTG and multi-ESSs operating strategies.

The Technical to Realize Variable Speed Constant Frequency Operation of Large Wind Turbine Generator

In this paper, through the introduction of the existing various mainstream wind turbine model, understand all kinds of operation mode and control method of wind turbines, contrast to put forward all kinds of wind turbine operation mode and control methods of the advantages and disadvantages, comprehensive put forward more effective technology of large wind turbines to realize variable speed constant frequency operation method, as well as for large wind turbines to realize variable speed constant frequency technology methods of the future.

Three-Stage Fuzzy Coordinator for Dynamic Stability Enhancement of Multi-Machine Power System Considering Various Penetration Levels of Wind Turbines

Disconnection of large wind turbine generators (WTGs) in renewable-integrated power systems has been well-recognized as one of the main origins of system instability. The ongoing study aims at establishing a three-stage fuzzy coordinator (TSFC) intended to enhance the power system stability encountering with major outages of large WTGs. The new TSFC employs wide area measurement system (WAMS) for a global coordination in multi-machine power system. The proposed TSFC founds a fuzzy logic coordination basis for tuning the interactions of multiple control devices. To this end, the WAMS-based TSFC is devised to end in performance harmonization of multiple control devices including automatic voltage regulator (AVR), power system stabilizer (PSS), and static var compensator (SVC). The TSFC receives the normalized voltage and rotor angle deviations of all machines and also the penetration level of wind farms as the input signals. The penetration level as the input signal determines the coordination strategy in three stages. In the sequel, based on the expert knowledge and analyzing the established rules, the TSFC generates output control signals broadcasted to the AVR, PSS, and SVC concurrently. Considering different penetration levels of WTGs, extensive numerical studies have been conducted to evaluate performance of the new coordinator.

Fabrication of a Scaled MgB2 Racetrack Demonstrator Pole for a 10-MW Direct-Drive Wind Turbine Generator

Field windings made of MgB2 wires or tapes are considered for their potential to reduce volume, weight, and cost of large offshore wind turbine generators. To gain experience of how to use this relatively new material in full-scale generators, tests of different winding methodologies and techniques are needed. In this paper, we describe in detail the steps used to wind a racetrack coil with a length of 1 m and a width of 0.5 m out of 4.5 km of MgB2 superconducting tape. The width corresponds to a full-scale pole of a 10-MW generator, whereas the length of the straight section is shorter than the corresponding full-scale pole. The coil was built up of ten double pancake coils. Each double pancake coil was wet wound using a semiautomatic winding process, where Stycast 2850 was applied directly to the MgB2 tape without any other dedicated electrical insulation. The strengths and weaknesses of the winding process are discussed and compared to the dry-winding method.

Electromagnetomechanical Coupled Vibration Analysis of a Direct-Drive Off-Shore Wind Turbine Generator

In large direct-drive off-shore wind turbine generators one challenge is to engineer the system to function securely with an air gap length of about a thousandth of the outer rotor diameter. Compared to the large diameter of the generator rotor, the rolling element bearings can only be constructed with a relatively limited size. This makes it challenging to design appropriate constructions able to transmit the large applied magnetic forces encountered in the air gap of direct drive wind turbine generators. Currently, this challenge is met by designing stiff heavy rotors that are able to withstand the forces in the air gap. Incorporating flexibility into the design of the rotor structure can lead to a lighter less expensive rotor. In order to be able to do this the magnetomechanical coupling in the air gap and its effect on the structural dynamics need to be taken into account when predicting the intended flexibility. This paper introduces an approach for a multiphysical modal analysis that makes it possible to predict the dynamics of the strongly coupled magnetomechanical system. The new method is validated using measurements of a simple lab setup. It is then applied to a single-bearing design direct-drive wind turbine generator rotor to calculate the changes of the structural dynamics caused by the electromagnetomechanical coupling.

Superconducting light generator for large offshore wind turbines

Offshore wind market demands higher power rate and reliable turbines in order to optimize capital and operational cost. These requests are difficult to overcome with conventional generator technologies due to a significant weight and cost increase with the scaling up. Thus superconducting materials appears as a prominent solution for wind generators, based on their capacity to held high current densities with very small losses, which permits to efficiently replace copper conductors mainly in the rotor field coils. However the state-of-the-art superconducting generator concepts still seem to be expensive and technically challenging for the marine environment. This paper describes a 10 MW class novel direct drive superconducting generator, based on MgB2 wires and a modular cryogen free cooling system, which has been specifically designed for the offshore wind industry needs.

Permanent Magnet Generator with Ventilation Flues between Poles in the Clover Leaf Structure Rotor for a Large Wind Turbine Generator System

Permanent Magnet Generator with Ventilation Flues between Poles in the Clover Leaf Structure Rotor for a Large Wind Turbine Generator System

Modelling and control of a multi-phase permanent magnet synchronous generator and efficient hybrid 3L-converters for large direct-drive wind turbines

A novel full-size wind power conversion system based on a multiphase permanent magnet synchronous generator (MPPMSG) and hybrid multi-converter system using 3-level neutral-point-clamp converters (3L-NPC) for high-power direct-drive wind turbines is proposed in this study. Higher efficiency, lower harmonics is achieved by replacing the traditional 2-level converter cells with 3-level cells. Circulating current is eliminated by using hybrid connection for multiphase generator design to replace the commonly used parallel converter structure for 3-phase generator design, the issues for neutral-point voltage imbalance is also eliminated. The mathematical model of MPPMSG and variable-speed control strategy are built and verified in PSCAD/EMTDC. A 3.5 kVA MPPMSG prototype machine and a set of hybrid 3L multi-converter systems are built. The experimental results validate the model and the effectiveness of the control strategies.

大型風力用発電機の技術動向と高温超伝導技術の適用可能性

Development and introduction of wind power generation have recently advanced in the R & D of renewable energies. Scaling-up of wind turbines is one of recent R & D trends because of the scale merits. In the wind farms in Europe, a significant number of 5 MW turbines are being installing. Further increase in the turbine size is expected. There are high expectations for a break-thought technology that will enable to develop light weight and compact wind turbine generators with large capacity of more than 10 MW. Applying high temperature superconducting (HTS) technology to the wind turbine generators can provide the light weight and compact design, since the magnetic field can be higher than that of conventional generators and the iron core can be considerably reduced. Therefore, it is considered that the application of the HTS technology to the wind turbine generator is one of the key issues to overcome the technical power limit of conventional wind turbine generators. This article reviews the recent technical trends of large capacity wind turbine generators and related R & D problems. In the article, the recent studies on the electromagnetic design of the HTS wind turbine generators are reviewed. The features of the design of HTS wind turbine generators are summarized.

Fault-Tolerant Control for a Modular Generator–Converter Scheme for Direct-Drive Wind Turbines

A modular power electronic converter, with a cascaded H-bridge multilevel inverter, has been proposed as the grid interface for a large direct-drive wind turbine generator. The present study is to investigate the potential and requirement of fault-tolerant operation in such a system. As each module is connected to isolated generator coils, tolerance to a module or coil fault is possible if the affected module can be bypassed, whereas the control of the healthy modules can be adjusted accordingly. A boost rectifier scheme on the machine side of the power conversion stage has been developed for this purpose, featuring control of the coil current without measuring the electromotive force. A coordinated dc-link voltage controller has been developed, which can rapidly raise the dc-link voltage of the remaining modules to compensate for the loss of a module while ignoring the ripple in the dc link due to low-frequency inverter switching. The ability of the resultant system to tolerate module faults has been demonstrated on a small-scale laboratory prototype.

Synthesis on PI-based pitch controller of large wind turbines generator

In this paper, proportional and integral (PI) pitch controller is analyzed and designed for a large wind turbine generator (WTG) by using graphical approach. Firstly, the transfer function of the wind turbine which including a time delay in the hydraulic pressure driven unit of pitch control system is derived. The complete stabilizing set in the plain of proportional–integral gains can then be drawn and identified immediately based on the presented method, rather than computed mathematically. The influence of the time delay in hydraulic pressure driven of pitch unit on the stability region of PI controller is analyzed as well. Finally, the proposed techniques are verified by using simulation results to the actual model of WTG.

Sensored and sensorless speed control methods for brushless doubly fed reluctance motors

The study considers aspects of scalar V/f control, vector control and direct torque (and flux) control (DTC) of the brushless doubly fed reluctance machine (BDFRM) as a promising cost-effective alternative to the existing technological solutions for applications with restricted variable speed capability such as large pumps and wind turbine generators. Apart from providing a comprehensive literature review and analysis of these control methods, the development and results of experimental verification, of an angular velocity observer-based DTC scheme for sensorless speed control of the BDFRM which, unlike most of the other DTC-concept applications, can perform well down to zero supply frequency of the inverter-fed winding, have also been presented in the study.

J0503-2-6 風力発電機タワーに作用する風荷重の評価(風力発電(2))

In late years, the renewable energy use is promoted, and, additionally, large-scale windfarms are constructed on a global scale by development of large and high efficiency wind turbine generator system (WTGS). As a WTGS grows larger, safety of WTGS tower is becoming more important. Wind loads acting on a WTGS consist of extreme wind condition and normal operating condition. About a extreme wind condition, there are already some studies, and evaluation way is suggested, but very few studies related to a wind load at a normal operating conditions, hi this study, evaluation of the equation for WTGS tower base moment suggested by Ishihara et al. and comparison with actual survey value in JSW WTGS J70 at normal operating condition are carried out.

Characteristic Study of Vector-controlled Doubly-fed Induction Generator in Stator-flux-oriented Frame

The doubly-fed induction generator (DFIG) is a “special” variable-speed induction machine that is widely utilized in modern large wind turbine generators. This article focuses on the DFIG characteristic study in the stator-flux-oriented frame. Compared to traditional approaches, the specific features of this article are (1) a DFIG steady-state model in the d-q reference frame, (2) simulation-based characteristic study under general d-q control strategies in the stator-flux-oriented frame, (3) a numerical iteration technique, (4) power simulation from both the stator and rotor paths, and (5) an integrated study that enables assessment of various DFIG parametric data simultaneously in an integrative environment. In addition, transient simulation using the MatLab SimPowerSystem is developed to validate the effectiveness of steady-state results and to further investigate a DFIG in a transient environment. Extensive simulation-based analysis is performed to inspect how DFIG characteristics are affected by different d-q control conditions in the stator-flux-oriented frame, such as torque-speed and real and reactive power versus speed characteristics.