Large-scale Wind Turbine Generators Research Articles

Establishing the Importance of Operating Temperature in the Structural Integrity of Large-Scale Direct-Drive Wind Turbine Generators

Direct-drive generators are recognised for their low maintenance compared with conventional drivetrains, largely due to their fewer working parts. However, consequent to low-speed operation, these machines necessitate large diameters and are subject to rigorous stiffness requirements. Significant internal and external forces influence structural integrity, so to design them efficiently, consideration of all operating parameters is imperative. Therefore, through Finite Element Analysis, this paper sets out to quantify the influence of each operating parameter on the integrity of a parametrically optimised rotor structure under established operating conditions and introduces operating temperature to the current models. An environmental impact analysis of the optimised rotor structure and cost analyses of both the optimised and unaltered structures are carried out simultaneous to the design process. We find the use of parameter optimisation alone to be insufficient for rotor structures of this scale due to high increased mass and costs of manufacture. A significant finding from this study is that the thermal effects on large-scale direct-drive generator structures may be vastly underestimated and have a much greater influence on structural integrity than first thought.

Influence of the Rated Revolution on the Basic Performance of Large-Scale Wind Turbine Generators

Influence of the Rated Revolution on the Basic Performance of Large-Scale Wind Turbine Generators

Optimization study of the main parameters of different types of wind turbine generators * * This work was supported in part by the National Natural Science Fund under Grant 52071090, in part by the Doctoral Start-up and Postgraduate Fund under Grant R17062, and in part by the Young Innovative Talents in Colleges and Universities of Guangdong Province under Grant 2019KQNCX046.

The research and development of large-scale wind turbine generators have become a future trend in green renewable energy field from the dual perspectives of the environment and economics. In this work, an electrical design method is first proposed and applied to different types of wind turbine generators, including the high-temperature superconducting (HTS), the permanent magnet, and the traditional copper generators. The optimal electrical designs of the three types of 10 MW wind turbine generators are then created based on the developed design program. Second, the influences of the rated revolution on the basic performance parameters of the HTS generator are investigated, and the results are compared with those of the other two types of generators. It is found that the generator weight decreases with the increases of the rated revolution and the stator outer diameter, and the optimal rated revolution for a generator with a large stator outer diameter is determined to be 40 min−1. Moreover, the weight of the field parts is found to have the same regulation rule as the generator weight. Finally, the design results of the three types of wind turbine generators are comparatively discussed, and it is found that the HTS wind turbine generator is superior to its two counterparts.

Failure prediction, monitoring and diagnosis methods for slewing bearings of large-scale wind turbine: A review

Slewing bearings for large-scale wind turbine generator system (WTGS) are critical components to achieve optimum aerodynamic power capture by adjusting the nacelle and blades. Slewing bearings failures, including Blade/yaw bearings, always cause serious consequences, such as pitching failure, low energy output and currentinstability et al. Therefore, it is urgent to predict and assess the damage failure of slewing bearings in order to make a reasonable management and maintenance solution. However, there are limited literatures and standard methods for slewing bearing failure prediction, monitoring and diagnosis in the wind power industry so far. In this work, current situation of researches on wind turbine slewing bearing is summarized systematically. Given small numbers of references available for pitch and yaw bearings, failure prediction, monitoring and diagnosis methods of slewing bearings for industries are reviewed and summarized, which can be potentially used for wind energy industry.

Novel differential protection using model recognition and unsymmetrical vector reconstruction for the transmission line with wind farms connection

The large-scale integration of different kinds of wind farms (WFs) in a transmission grid can bring special adaptability issues to the traditional phasor-based line differential protection in both the transient and steady states. In this paper, a novel composite fault model based differential protection (CFMDP) is proposed. The CFMDP detects the fault status by evaluating the consistency between the sampled fault data and the pre-defined differential model. Since the full-frequency fault information in time-domain is directly used in the consistency calculation, the CFMDP method performs better transient behaviours than the conventional scheme. Besides, the compensated currents are used to build the differential model, which overcomes the 'over angle difference' caused steady-state adaptability issue in the phasor based differential relay. This steady-state protective issue mainly happens with the interphase faults in large-scale Type-IV wind turbine generators (WTGs) integrated power grid. The electro-magnetic transient (EMT) simulation results demonstrate the effectiveness and merits of the proposed CFMDP schemes.

공급신뢰도 측면에서의 신재생에너지발전단지와 연계된 BESS의 운용 알고리즘 개발

This paper proposes a probabilistic reliability evaluation model and algorithm for the power system considering wind turbine generator (WTG) and battery energy storage system (BESS) in viewpoint of power system reliability. A large-scale wind turbine generator (WTG) can creates significant power fluctuations and should affect the stability, frequency control and then reliability of the power system. Therefore, wind power should be limited to supply the percentage of load. The output of WTG cannot be predicted accurately and so results in significant fluctuations in power supply balance. Therefore, it is difficult to control the power balance between supply and demand. However, it can be controlled by installing the BESS. The BESS may smooth the fluctuation of the WTG power output. This paper proposes reliability based alternative algorithm in order to simulate the effects of the interaction of multiple WTG and BESS newly. Additionally, this paper presents sample system studies that single BESS as well as multi-BESS are simulated by handwork very clearly. Futhermore, the reliability effects of BESS according to a couple of different BESS operation rules and conditions are demonstrated in sample system case study.

Reliability evaluation of power system considering wind generators coordinated with multi‐energy storage systems

This study proposes a new methodology for a probabilistic power system reliability evaluation using a Monte Carlo simulation in case of multi-energy storage system (ESS) installed at wind farms. A large-scale wind turbine generator (WTG) creates significant power fluctuations and effect the stability, frequency control, and then reliability of the power system. A high penetration of wind farms can result in unacceptable variations in the frequency and voltage in the power system. The significant power fluctuation impact of the WTG can, however, be reduced by installing an ESS. The proposed model can facilitate the reliability analysis and evaluation in a viewpoint of the contribution of each ESS installed at multiple wind farms integrated to a power system. The proposed method can also be used to assess the reasonable capacity of an ESS in the power system from a sensitivity analysis. A case study is demonstrated for the proposed model and methodology using a power system with similar size to the one in Jeju Island, South Korea.

Characteristics Analysis of Inertia Damping of Grid-Connected System of Direct-Drive Wind Power Generation

As large-scale direct-drive wind turbine generator set is connected to the grid, the power system will face problems such as reduced inertia and insufficient frequency modulation capability. The control of wind turbine virtual inertia is an important way to solve this problem. Therefore, this paper takes the direct-drive wind power generation system as the research object, draws lessons from the multi-time scale modeling idea, and based on the electrical torque analysis, establishes the DC voltage time model with the wind turbine virtual inertia control. Based on this, inertia damping characteristics of direct-drive wind power grid-connected system are analyzed. The results show that the dynamic characteristic parameters of the system are affected by many factors, among which the equivalent inertia coefficient of the system is mainly affected by DC capacitance, DC bus voltage and wind turbine virtual inertia control parameters. Damping coefficient is mainly affected by steady-state operating point and DC voltage proportional control parameter K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pu</sub> . The synchronization coefficient is mainly affected by steady-state operating point and DC voltage integration control parameter K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">iu</sub> . The correctness of mechanism analysis of inertia damping characteristics of the whole system is verified by simulation, which provides a certain theoretical reference for inertia damping research of electronic power system.

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.

Overview Study on Electrical Design of Large-Scale Wind Turbine HTS Generators

High-temperature superconductor generators for 10-MW class wind turbine systems are being favored due to their light weight, small size, and high efficiency. In this paper, R&D status of the HTS machines in the world is reviewed, and different design topologies of 10-MW class wind turbines with HTS generators (WTHGs) are introduced in brief. In addition, the electrical designs of large-scale wind turbine generators (WTGs) with HTS field coils, copper field coils, and PM field pole are compared. And then, the influence of the stator outer diameter and the operating temperature of three-type WTHGs on their generator weight, efficiency, and field part weight is described and compared. Finally, the design results and costs for three-type 10-MW WTGs are discussed comparatively.

Three-stage Evolution Mechanism of Multiple Stability Problems and Control Strategies of AC/DC Power System with Large-scale Wind Turbine Generators

There exists interactive evolution process of multiple stability problems of AC/DC power system with large-scale HVDC and wind power, such as voltage or frequency fluctuation and power oscillation, which can be caused by HVDC commutation failure. Further research is required on the evolution mechanism and control strategies of this kind of power system. In this paper, firstly three-stage evolution mechanism is proposed, including large-scale wind turbine generators tripping off caused by transient overvoltage, transient angle instability caused by power flow transferring in weak transmission section, and out-of-step separation caused by cross-regional power oscillation. Secondly, evolution processes and typical models of different stability problems are studied deeply. The prevention and control strategies are proposed. Finally, simulation results and analysis based on real-sized power grid in China prove the rationality and effectiveness of the proposed three-stage evolution mechanism and control strategies.

대용량 풍력발전기용 수랭식 냉각장치 적용의 타당성 연구

축 방향 자속 영구자석 발전기(Axial flux permanent magnet generator, AFPM)는 기존 발전기와 비교하면 구조가 간단하고 높은 효율을 가지고 있어, 높은 신뢰성이 요구되는 대용량 직접구동형 해상풍력발전기에 적용하려는 연구가 활발히 이루어지고 있다. 그러나, 대용량 AFPM 발전기 개발에 어려운 문제 중 하나는 전력 생산 시 고정자에서 발생하는 과열로서, 이는 전력 생산에 심각한 문제를 야기시킨다. 본 연구에서는 2.5 MW급 AFPM 발전기에 적용되고 있는 기존의 공랭식 냉각장치를 대체 할 수 있는 수랭식 냉각장치를 제안하였으며, 전자기 해석 및 열-유동 연성해석을 통하여 열적 거동을 평가하여 기존의 냉각장치와 비교하였다. 제안된 수랭식 냉각장치의 성능은 기존의 공랭식 냉각장치와 비슷하지만, 상대적으로 냉각효율이 높아 설비 중량을 절반 수준의 경량화 할 수 있어 기존의 냉각장치를 대체 할 수 있다고 판단된다.

Fatigue Analysis of Large-scale Wind turbine

The paper does research on top flange fatigue damage of large-scale wind turbine generator. It establishes finite element model of top flange connection system with finite element analysis software MSC. Marc/Mentat, analyzes its fatigue strain, implements load simulation of flange fatigue working condition with Bladed software, acquires flange fatigue load spectrum with rain-flow counting method, finally, it realizes fatigue analysis of top flange with fatigue analysis software MSC. Fatigue and Palmgren-Miner linear cumulative damage theory. The analysis result indicates that its result provides new thinking for flange fatigue analysis of large-scale wind turbine generator, and possesses some practical engineering value.

Performance Comparison of 10-MW Wind Turbine Generators With HTS, Copper, and PM Excitation

A conceptual structure for large-scale wind turbine generators (WTGs) with high-temperature superconductor (HTS) excitation has been proposed. A novel electrical design method for this concept has been developed that can be also applied to conventional generators with copper coil and permanent magnet (PM) excitation with some modifications. Using the modified design program, electrical designs of 10-MW synchronous WTGs with HTS coil, copper coil, and PM excitation are conducted, and the influence of machine parameters (such as magnetic flux density in rotor iron cores, pole pitch, and stator outer diameter) on the basic generator performance is clarified. Based on these results, the optimized designs of three kinds of WTGs rotating at the low speeds of 8 min <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and 10 min <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> are performed, and their basic performance is studied.

Study of Sub-Synchronous Control Interaction (SSCI) Based on the Test Signal Method

Large-scale wind turbine generators with power electronic converters that operate near series compensated transmission lines are susceptible to un-damped sub-synchronous oscillations. This sub-synchronous oscillation is called Sub-synchronous Control Interaction (SSCI). Based on PSCAD / EMTDC simulation platform the establishment of Double Fed Induction Generator (DFIG) equivalent inverter controlled sources and network model, and verify the correctness of the equivalent model. Analysis the impact of series compensation and rotor-side converter PI parameters characteristic of the SSCI based on test signal method and time-domain simulation method. The results show that increasing the degree of series compensation , inner gain constant increases and inner integral time decreases will help increase SSCI, outer ring of PI parameters has little effect on the SSCI .

Study on Sub-Synchronous Control Interaction (SSCI) of Wind-Power Generator

Large-scale wind turbine generators with power electronic converters that operate near series compensated transmission lines are susceptible to un-damped sub-synchronous oscillations. This sub-synchronous oscillation is called Sub-synchronous Control Interaction (SSCI). With the rapid development of wind power technology, SSCI emerges as a new sub-synchronous oscillation phenomenon. The first SSCI event occurred for a wind farm in America in2009, which resulted in damage to the wind turbines. The origin of SSCI is presented and its characteristics of different types of wind turbines are summarized. Then the research prospect on this field is explored.

Numerical Analysis and Design of Damper Layer for MW-Class HTS Synchronous Wind Turbine Generator

This paper presents a numerical analysis on MW-class high-temperature superconducting (HTS) synchronous generator, especially focusing on damper layer design. Our research program to develop a large-scale HTS wind turbine generator (WTG) core technology, a two-dimensional electromagnetic FEM model of the direct-drive HTS WTG, comprised of 24 air-core type HTS race track coils (24 poles), has been built. The damper is used for stable operation of HTS field coil against varying magnetic field by change of rotation speed. This model is designed to obtain basic operating parameters for HTS WTG, including magnetic field distribution and induced electromotive force, in static and transient condition. First, the parameters in static condition, which means that the rotating speed is constant, are compared with our design parameters to confirm the feasibility of our numerical analysis. Second, in transient condition, we focused on the reaction between rotating magnetic field and its stator components, damper, and armature winding. By changing damper material having different electrical conductivity and magnetic permeability, we concluded our damper design to be applicable to our MW-class HTS synchronous generator model.

Fluid-Oscillation Coupled Analysis for HAWT Rotor Blade (One Degree of Freedom Weak Coupling Analysis with Hinge-Spring Model)

Since large-scale commercial wind turbine generator systems such as MW-class wind turbines are becoming widely operated, the vibration and distortion of the blade are becoming larger and larger. Therefore the soft structure design instead of the solid-design is one of the important concepts to reduce the structural load and the cost of the wind turbine rotors. The objectives of the study are development of the fluid-structure coupled analysis code and evaluation of soft rotor-blade design to reduce the unsteady structural blade load. In this paper, fluid-structure coupled analysis for the HAWT rotor blade is performed by free wake panel method coupled with hinge-spring blade model for the flapwise blade motion. In the model, the continuous deflection of the rotor blade is represented by flapping angle of the hinge with one degree of freedom. The calculation results are evaluated by comparison with the database of the NREL unsteady aerodynamic experiment. In the analysis the unsteady flapwise moments in yawed inflow conditions are compared for the blades with different flapwise eigen frequencies.

Intelligent control for large-scale variable speed variable pitch wind turbines

Large-scale wind turbine generator systems have strong nonlinear multivariable characteristics with many uncertain factors and disturbances. Automatic control is crucial for the efficiency and reliability of wind turbines. On the basis of simplified and proper model of variable speed variable pitch wind turbines, the effective wind speed is estimated using extended Kaiman filter. Intelligent control schemes proposed in the paper include two loops which operate in synchronism with each other. At below-rated wind speed, the inner loop adopts adaptive fuzzy control based on variable universe for generator torque regulation to realize maximum wind energy capture. At above-rated wind speed, a controller based on least square support vector machine is proposed to adjust pitch angle and keep rated output power. The simulation shows the effectiveness of the intelligent control.

Review of wind turbine control

The literature on the design of control sysems for medium- and large-scale wind turbine generators is reviewed. The vast majority of relevant literature is concerned with the control of horizontal-axis machines. Emphasis is given to public-utility service machines with power outputs in the range hundreds to thousands of kilowatts. This work was prompted by the need to determine specific objectives for the turbine control system. The control system is an integral part of the wind turbine; it is stochastic and non-linear and the different wind-turbine configurations pose a variety of design goals. The review highlights the lack of a clear consensus on the role of the control system and an inadequate treatment of dynamic and stochastic issues. Wind-turbine control is an application area with an interesting set of problems for control engineering. These problems have not been adequately solved and continue to pose challenges to the control community. Wind-turbine control issues are therefore important, since ...