改进的双馈风电机组故障穿越控制策略研究

基于传统矢量控制技术,该文提出一种改进的矢量控制技术来抑制双馈感应电机故障期间的转子过电流,以提高双馈风电机组故障穿越能力。从分析传统矢量控制技术入手,提出一种改进的矢量控制技术,其主要特点是反映定子电压瞬态对转子电流的影响,但并未增加控制的复杂程度。从理论的角度对所提方案能提高双馈风电机组故障穿越能力的机理进行深入分析。最后,对基于PSCAD/EMTDC软件环境下搭建的2 MW双馈风电机组模型进行仿真研究。仿真结果表明所提方案能有效抑制双馈感应电机故障期间的转子过电流,从而提高双馈风电机组的故障穿越能力。     

双馈感应风力发电系统低电压穿越控制

传统的双馈感应发电机(DFIG)矢量控制方案忽略了定子暂态磁通,导致当电网出现故障时控制性能恶化.为了提高电网故障下DFIG的不间断运行能力,将矢量控制与自抗扰控制器结合起来,利用扩张状态观测器估计出定子暂态磁通和电机参数误差对系统的影响并加以补偿.仿真结果表明该文提出的控制方法削弱了电网故障时DFIG的转子暂态电流峰值和电磁转矩波动,有效地保护了转子变频器和风力机机械结构,而且对电机参数误差具有鲁棒性.     

双馈风力发电系统在电网故障下的动态响应分析

该文在建立电网故障时双馈发电机定子电压空间矢量模型的基础上,对双馈感应发电机以及变换器在电网不对称故障及对称故障时的动态响应特性进行了详细的定量和定性分析,揭示了双馈发电系统暂态故障响应的本质及各电磁量的变化规律.推导出了双馈发电机电网故障电流的最大值及其发生时刻.并在此基础上,提出了实现风电机组故障穿越技术的基本准则.     

风力发电用双馈感应发电机控制策略的研究

该文从并网风力发电系统的基本特性出发，在分析双馈感应电机数学模型及其定子磁链定向矢量控制的基础上，论证了其有功功率和无功功率的独立控制的可行性并给出了PID双闭环控制方案。利用Matlab／Simulink平台，仿真研究并验证了该控制方案的正确性，对实际软硬件系统的设计与调试具有一定的指导意义。     

滞环矢量控制在双馈风力发电机中的应用

滞环电流控制方法以其动态响应速度快,电路跟踪性能好的优点而获得了广泛的应用和发展。基于双馈发电机数学模型,采用定子磁场定向的矢量控制．转子侧选用改进型滞环电流控制,建立了有功功率、无功功率解耦的控制策略。利用PSCAD软件．建立了仿真控制模型并进行了仿真计算。仿真结果表明,该控制系统能有效地实现双馈发电机有功、无功功率的解耦,验证该控制方案的正确性和有效性。     

双馈风电系统高电压穿越的节能控制策略

在研究双馈风力发电系统高电压穿越的节能控制问题的过程中,考虑到外部风力环境变化较大,需保持变换器的稳定性节能控制。传统节能控制方法不仅动态及稳态性能差,而且节能控制策略相对复杂。为了提高节能控制效果,提出采用串联网侧变换器的双馈风电系统高电压穿越的节能控制策略,向串联网侧变换器的控制向电机定子侧和电网间添加合理的控制电压,按照电网电压定向的同步旋转,给出d-q轴系下SGSC的电压控制方程,保持DFIG定子端电压不变,过滤DFIG定子磁链中的暂态直流分量。当双馈风电系统电压及电流均不超限时,对转子侧变换器和并联网侧变换器的输出电压矢量进行节能控制,使双馈风电系统为电网提供最大程度的无功支持,快速恢复电网电压。仿真实验结果表明,所提策略具有很高的节能控制性能。     

双馈风电机组的高电压穿越控制策略

分析了广义电网电压骤升(含对称、不对称骤升)故障下双馈风电机组电磁暂态过渡过程,评估了影响机组高电压穿越运行的关键因素,并梳理了电压骤升、骤降故障诱发双馈机组脱网机理的异同。提出了一种基于瞬态灭磁控制和无功电流支持的双馈机组高电压穿越控制方案。仿真和实验结果表明,所述方案能够显著加快故障电网条件下双馈感应电机定子磁链中直流、负序分量的衰减,进而快速抑制机组电磁转矩和母线电压的波动;同时能够满足并网规范对机组无功电流输出的要求,实现机组的故障穿越运行。     

基于减载的双馈风电机组联合故障穿越方案

分析电网电压故障期间双馈风电机组功率流动关系、减载控制原理以及减载能力影响因素,并提出一种基于减载的双馈风电机组联合故障穿越方案,该方案包括:1)定子电流实时跟踪的减载故障穿越方案;2)直流侧卸荷电路.前者主要抑制双馈感应电机转子故障电流,后者主要稳定直流母线电压.最后,基于PSCAD/EMTDC仿真软件搭建的模型,验...     

双馈风力发电系统故障不脱网运行能力研究

论述了变速双馈风力发电系统电网故障时的控制策略,提出了电网故障时转子过流保护、机械振荡阻尼控制、电压支持控制和无功功率泵升控制等策略,并通过仿真分析了三相短路故障时变速双馈风电系统的动态性能,采用该文的控制策略可有效保护变换器,抑制机械振荡,提供一定的电压支持和无功功率泵升能力,使双馈风电系统具有较好的故障不脱网运行能力,并提高了整个电力系统的稳定性.     

交流励磁变速恒频双馈风力发电系统并网控制策略与试验

提出了一种双馈风力发电系统并网控制策略。给出了双馈电机在同步旋转坐标系里的数学模型,采用电网电压定向矢量控制,对双馈电机的数学模型进行了简化。结合交流励磁双馈电机风力发电系统并网的实际情况,提出了分段并网控制策略,给出了各个控制器的设计方法。在实验室所搭建的变速恒频双馈电机风力发电试验平台,作了相应的验证性试验。试验结果证明,所提出的方法可以使双馈电机实现平滑并网。     

双馈式风电机组传动系统动态特性研究

针对双馈式风电机组柔性传动系统运行稳定性问题,采用集中参数质量法建立风电机组柔性传动模型,在考虑外部风载、齿轮副啮合刚度、啮合阻尼和综合啮合误差激励条件下,建立了齿轮箱内部各级齿轮副动力学方程;以市场成熟的1.5MW双馈式风电机组为计算对象,计算了柔性传动系统固有频率和齿轮箱各级齿轮动态啮合力;通过雨流计数法对齿轮动态啮合力进行数据分析,研究了传动系统运行稳定性。研究结果表明,齿轮副啮合力呈现高频波动,具有很强的时变特性,通过雨流计数分析,动态啮合力幅值与频次成正态分布规律;传动系统一阶扭转振动频率与风轮面内一阶摆阵频率偏差为6.8%,通过降低主轴质量约9.5%,提高了传动系统一阶扭转频率约11.5%,与风轮面内一阶摆阵频率偏差达16.4%。研究结果可为风电机组传动系统设计、轴承寿命计算和可靠性研究提供参考。     

Control of a doubly fed induction generator in a wind turbine during grid fault ride-through

This paper analyzes the ability of a doubly fed induction generator (DFIG) in a wind turbine to ride through a grid fault and the limitations to its performance. The fundamental difficulty for the DFIG in ride-through is the electromotive force (EMF) induced in the machine rotor during the fault, which depends on the dc and negative sequence components in the stator-flux linkage and the rotor speed. The investigation develops a control method to increase the probability of successful grid fault ride-through, given the current and voltage capabilities of the rotor-side converter. A time-domain computer simulation model is developed and laboratory experiments are conducted to verify the model and a control method is proposed. Case studies are then performed on a representatively sized system to define the feasibility regions of successful ride-through for different types of grid faults.     

An improved fault ride-through strategy for doubly fed induction generator-based wind turbines

Keeping the generators operating during transient grid faults becomes an obligation for the bulk wind generation units connected to the transmission network and it is highly desired for distribution wind generators. A proposed scheme is implemented to keep the wind-power DFIG operating during transient grid faults. Challenges imposed on the generator configuration and the control during the fault and recovering periods are presented. A comprehensive time domain model for the DFIG with the decoupled dq controller is implemented using Matlab/Simulink software. Intensive simulation results are discussed to ensure the validity and feasibility of the proposed fault ride through technique. The scheme protects the DFIG components, fulfills the grid code requirements and optimises the hardware added to the generator.     

Innovative improvement of a drag wind turbine performance

Drag type wind turbines have strong potential in small and medium power applications due to their simple design. However, a major disadvantage of this design is the noticeable low conversion efficiency. Therefore, more research is required to improve the efficiency of this design. The present work introduces a novel design of a three-rotor Savonius turbine with rotors arranged in a triangular pattern. The performance of the new design is assessed by computational modeling of the flow around the three rotors. The 2D computational model is firstly applied to investigate the performance of a single rotor design to validate the model by comparison with experimental measurements. The model introduced an acceptable accuracy compared to the experimental measurements. The performance of the new design is then investigated using the same model. The results indicated that the new design performance has higher power coefficient compared with single rotor design. The peak power coefficient of the three rotor turbine is 44% higher than that of the single rotor design (relative increase). The improved performance is attributed to the favorable interaction between the rotors which accelerates the flow approaching the downstream rotors and generates higher turning moment in the direction of rotation of each rotor.     

Intelligent approach to maximum power point tracking control strategy for variable-speed wind turbine generation system

To achieve maximum power point tracking (MPPT) for wind power generation systems, the rotational speed of wind turbines should be adjusted in real time according to wind speed. In this paper, a Wilcoxon radial basis function network (WRBFN) with hill-climb searching (HCS) MPPT strategy is proposed for a permanent magnet synchronous generator (PMSG) with a variable-speed wind turbine. A high-performance online training WRBFN using a back-propagation learning algorithm with modified particle swarm optimization (MPSO) regulating controller is designed for a PMSG. The MPSO is adopted in this study to adapt to the learning rates in the back-propagation process of the WRBFN to improve the learning capability. The MPPT strategy locates the system operation points along the maximum power curves based on the dc-link voltage of the inverter, thus avoiding the generator speed detection.     

基于状态监测的风电机组变桨系统故障诊断

以风电机组中故障率较高的变桨系统作为研究对象,从数据采集与监视控制系统的数据库中选择与变桨系统运行相关的特征参数,基于相似性原理,利用非线性状态评估方法,建立能够涵盖变桨系统全部正常运行状态的健康模型。当变桨系统发生故障时,会出现模型预测值与正常状态的偏差,根据每一个特征参数对偏差的影响来确定故障的原因。应用实例验证表明,该模型能够准确地识别故障类型,可以解决在排除故障及设备维修时,因缺少相关信息而造成停机时间过长、维修难度大等问题。     

Offshore wind turbine fault alarm prediction

Offshore wind operations and maintenance (O&M) costs could reach up to one third of the overall project costs. In order to accelerate the deployment of offshore wind farms, costs need to come down. A key contributor to the O&M costs is the component failures and the downtime caused by them. Thus, an understanding is needed on the root cause of these failures. Previous research has indicated the relationship between wind turbine failures and environmental conditions. These studies are using work‐order data from onshore and offshore assets. A limitation of using work orders is that the time of the failure is not known and consequently, the exact environmental conditions cannot be identified. However, if turbine alarms are used to make this correlation, more accurate results can be derived. This paper quantifies this relationship and proposes a novel tool for predicting wind turbine fault alarms for a range of subassemblies, using wind speed statistics. A large variation of the failures between the different subassemblies against the wind speed are shown. The tool uses 5 years of operational data from an offshore wind farm to create a data‐driven predictive model. It is tested under low and high wind conditions, showing very promising results of more than 86% accuracy on seven different scenarios. This study is of interest to wind farm operators seeking to utilize the operational data of their assets to predict future faults, which will allow them to better plan their maintenance activities and have a more efficient spare part management system.     

Control strategy of a wind turbine drive by an integrated model

In this paper, an integrated equivalent circuit is defined to analyse the operation of a wind generator–rectifier system connected to a DC link, with the electric machine consisting of a surface‐mounted permanent magnet synchronous generator (SPMG) directly coupled to the wind turbine. Such circuit is defined by integrating the models related to the electromechanical equations implemented into a Simulink® code, where the SPMG parameters are derived by the elaboration of sequences of magnetostatic FEM analyses. The integrated equivalent circuit can be very useful to examine the wind generator dynamics because of wind speed variations, and to analyse the influence of the electromechanical parameters on the energy output in order to identify the appropriate control strategies involving the regulation of the rotor speed, the DC link current and the blade pitch angle. In particular, a sensorless algorithm is implemented to estimate the main mechanical quantities (output torque and rotor speed) and to determine the wind speed by means of only electrical measurements. The comparison with an anemometer‐based solution shows that similar performances can be achieved in different operating conditions. The control strategies set up by the circuit model are verified on a 20 kW‐rated SPMG with outer rotor, comparing the sensor and sensorless approaches in terms of capability of energy production, dynamic promptness and sensitivity to parameter disturbances, also with wind turbulence. Copyright © 2008 John Wiley & Sons, Ltd.     

基于DVR的风电机组低电压穿越仿真研究

文章提出了基于三单相结构动态电压恢复器(DVR)的风力发电低电压穿越(LVRT)方案。当电网电压发生跌落时,通过串联接入DVR来产生补偿电压,从而维持风电机组定子端电压的恒定。该方案是风力发电与电能质量的有效结合,充分利用了DVR在较短的时间内较强的电压补偿能力。仿真结果表明,该方案有效地抑制了转子侧暂态电流的蹿升,并及时将电网电压恢复到额定值,表现出了良好的低电压穿越能力。