Vector control optimization of DFIGs under unbalanced conditions

Keller

Guo

et al. 2021

Preprint

Abstract. This paper presents the state-of-the-art technologies and development trends of wind turbine drivetrains – the energy conversion systems transferring the kinetic energy of the wind to electrical energy – in different stages of their life cycle: design, manufacturing, installation, operation, lifetime extension, decommissioning, and recycling. Offshore development and digitalization are also a focal point in this study. The main aim of this article is to review the drivetrain technology development as well as to identify future challenges and research gaps. Drivetrain in this context includes the whole power conversion system: main bearing, shafts, gearbox, generator, and power converter. The paper discusses current design technologies for each component along with advantages and disadvantages. The discussion of the operation phase highlights the condition monitoring methods currently employed by the industry as well as emerging areas. This article also illustrates the multidisciplinary aspect of wind turbine drivetrains, which emphasizes the need for more interdisciplinary research and collaboration.

Section: Power Convertermentioning

confidence: 99%

Wind turbine drivetrains: state-of-the-art technologies and future development trends

Keller

Guo

et al. 2021

Preprint

“…To reduce fatigue damage and noise and comply with standard limits, a suppression to the permissible level

2 %

for electromagnetic torque oscillations is required . Torque oscillation in surface‐mounted PMSGs mainly comes from two sources: Cogging effect due to the variable permeance of the air gap and Distortion of sinusoidal distribution of air gap flux density due to saturation, current ripple resulting from pulse width modulation (PWM), and low power quality of the grid. …”

Section: Numerical Simulationsmentioning

confidence: 99%

Evaluation of PMSG‐based drivetrain technologies for 10‐MW floating offshore wind turbines: Pros and cons in a life cycle perspective

Moghadam

2020

Wind Energy

This paper presents an in depth evaluation and comparison of three different drivetrain choices based on permanent-magnet synchronous generator (PMSG) technology for 10-MW offshore wind turbines. The life cycle approach is suggested to evaluate the performance of the different under consideration drivetrain topologies. Furthermore, the design of the drivetrain is studied through optimized designs for the generator and gearbox. The proposed drivetrain analytical optimization approach supported by numerical simulations shows that application of gearbox in 10-MW offshore wind turbines can help to reduce weight, raw material cost, and size and simultaneously improve the efficiency. The possibility of resonance with the first torsional natural frequency of drivetrain for the different designed drivetrain systems, the influence of gear ratio, and the feasibility of the application for a spar floating platform are also discussed.This study gives evidence on how gearbox can mitigate the torque oscillation consequences on the other components and how the latter can influence the reliability of drivetrain. KEYWORDSdrivetrain optimization, floating offshore wind turbine, life cycle assessment, permanent-magnet synchronous generator INTRODUCTIONThe capacity of offshore wind turbines and the distance from shores is rising rapidly, so that multigigawatt offshore wind farms based on multimegawatt floating turbines show potentials to be one of the dominant sources of power production in the future. The latter is due to availability of better wind resources, less turbulence, steadier winds, and less wind shear; easier transportation of larger turbines on the sea; technological developments in power electronic converters and direct current (DC) power transmission technologies; the establishments of required market infrastructures; and technological achievements in installation of turbines in deep waters, which lead to a considerable drop in the levelized cost of energy (LCOE) of offshore wind turbines. In spite of significant improvements, there are still no unanimous decision about the drivetrain system technology in offshore wind turbines. 1,2 Offshore wind reaches to 10-MW turbines or even higher, but there are still different interests between manufacturers in the selection of drivetrain technology. One reason is that the drivetrain in wind originally comes from available experiences in other industries, which has been modified over time. The latter has then been upscaled for higher powers with some modifications to reduce the production costs and improve the dynamic response. Because the wind turbines are developed for a wide range of power in various onshore/offshore, fixed/floating, two-/three-bladed rotors, upwind/downwind, high/medium/low wind, fix/variable speed, stall/active yaw, and stall/active pitch applications, a customized design of the drivetrain for the cost reduction and performance improvement is inevitable. Therefore, there is a need for a special drivetrain design for each power class for different applicati...

“…The induction generator electromagnetic torque oscillations happen significantly with the voltage frequency 50Hz and the third order harmonics as a consequence of the current and back emf harmonics caused by power electronic converter and the grid low power quality, and the second harmonic as a result of voltage unbalanced operations, [16,17]. The cogging effects between the stator and rotor teeth also result in the torque oscillation whose frequency depends on the numbers of machine slots and may not happen in integer multiples of 50Hz.…”

Section: Scenario Two: Internal and Torsional Excitationsmentioning

confidence: 99%

Experimental Validation of Angular Velocity Measurements for Wind Turbines Drivetrain Condition Monitoring

Moghadam

ASME 2019 2nd International Offshore Wind Technical Conference

2019

Drivetrain bearings are seen as the most common reason of the wind turbine drivetrain system failures and the consequent downtimes. In this study, the angular velocity error function is used for the condition monitoring of the bearings and gears in the wind turbine drivetrain. This approach benefits from using the sensor data and the dedicated communication network which already exist in the turbine for performance monitoring purposes. Minor required modification includes an additional moderate sampling frequency encoder without any need of adding an extra condition monitoring system. The additional encoder is placed on the low speed shaft and can also be used as the backup for the high speed shaft encoder which is critical for turbine control purposes. A theory based on the variations of the energy of response around the defect frequency is suggested to detect abnormalities in the drivetrain operation. The proposed angular velocity based method is compared with the classical vibration-based detection approach based on axial/radial acceleration data, for the faults initiated by different types of excitation sources. The method is experimentally evaluated using the data obtained from the encoders and vibration sensors of an operational wind turbine.