基于神经网络的风电机组变桨距恒功率控制系统的研究

风力发电的开发对增加我国能源供应、调整能源结构具有重要意义.为了优化风电系统的稳定性,本文利用神经网络在非线性建模方面的优越性,建立了一个基于神经网络的风电机组变桨距恒功率控制系统.该系统在BP神经网络变桨距模型的基础上,利用SIMULINK工具箱搭建了风电机组变桨距恒功率控制系统模型.经仿真和实践运行验证,该模型控制效果良好,能根据风速检测值调节桨距角,实现在不同风速段对发电机输出功率的恒定控制,具有良好的稳定性和快速收敛性.     

基于欧姆龙PLC的风电机组变桨距系统

在风力发电系统中,变桨距控制技术关系到风力发电机组的安全可靠运行,影响风力机的使用寿命,通过控制桨距角使输出功率平稳、减小转矩振荡、减小机舱振荡,不但优化了输出功率,而且有效的降低的噪音,稳定发电机的输出功率,改善桨叶和整机的受力状况。变桨距风力发电机比定桨距风力发电机具有更好的风能捕捉特性,现代的大型风力发电机大多采用变桨距控制。本文针对国外某知名风电公司液压变桨距风力机,采用可编程控制器（PLC）作为风力发电机的变桨距控制器。这种变桨控制器具有控制方式灵活,编程简单,抗干扰能力强等特点。本文介绍了液压变桨距系统的工作原理,设计了变桨控制器的软件系统。最后在国外某知名风电公司风力发电机组上做了实验,验证了将该变桨距控制器可以在变桨距风力机上安全、稳定运行的。     

PI调节控制器用于双馈风电机组的功率控制策略研究

本文提出了一种基于PI控制器利用非线性单纯形算法的功率控制策略,通过该控制器对控制参数进行优化,再结合变桨距控制法,实现对双馈风电机组功率的有效控制。经仿真结果证明,利用该控制器可以改善双馈风电机组功率控制系统的各项动态性能,提高控制精度,且具有良好的鲁棒性。     

风力发电系统功率解耦的控制方案

针对风力发电系统功率解耦控制存在时滞误差的问题,提出基于LM-Smith时滞补偿和误差修正的风力发电系统功率解耦控制方法,构建风力发电系统控制输入输出的参量模型,以及控制目标函数。采用LM-Smith算法进行参量的全局最优解计算,以最优解为训练向量进行时滞补偿和功率解耦控制,实现控制误差修正。仿真结果表明,采用该方法控制风力发电系统,功率的解耦性较好,提高了输出功率增益,在较大的负载范围内能有效实现稳定的电压输出。     

风电柔性直流输电控制策略的研究

柔性直流输电(Flexible High Voltage Direct Current,Flexible HVDC)技术作为一种新型输电技术,在风力发电领域有着显著的优势和广阔的应用前景。本文介绍了柔性直流输电系统的拓扑结构和工作原理,建立了基于空间矢量的数学模型,实现了有功功率和无功功率的解耦控制,并设计双闭环矢量控制器,利用matlab/simulink搭建整个仿真系统,对其运行情况进行了仿真。仿真结果表明,设计的控制器运行效果良好,能很好的实现对风电场功率的传输,具有抗干扰能力强,稳定性好,相应迅速等优点,适用于风电场柔性直流输电系统。     

基于DITC开关磁阻风力发电系统MPPT2-SMC控制

针对开关磁阻发电机(SRG)转矩波动大及难以快速精确调速的缺点,提出了二阶滑模控制(2-SMC)与直接瞬时转矩控制(DITC)相结合的复合控制方案,设计二阶滑模控制器,基于Matlab/simulink搭建风力发电系统模型。仿真结果表明,所用控制方案不仅实现了最大功率跟踪,有效降低了发电机转矩脉动,同时减小了输出功率的波动。     

基于UPFC风力发电系统控制优化研究

将统一潮流控制器用于风力发电系统,通过统一潮流控制器优秀的潮流调节功能,对风力发电系统中的功率调节进行有效改善,与传统风电直接接入电网时带来的谐波污染相比,统一潮流控制器的使用能给风力发电注入电力系统的谐波污染带来很大抑制作用,使得系统的功率补偿得到进一步优化。另外,对统一潮流控制器串联侧采用预测控制策略,使得系统的动静态性能有了很大提高,同时降低了控制器的复杂性,有利于EMI滤波器的数字化实现。通过Matlab仿真试验验证了以上策略的有效性和可行性,具有一定应用价值。     

基于模糊控制的风电机组变桨距控制

针对风力发电机组非线性、时变性的问题,提出采用模糊PID控制器作为变桨距控制器,在风速高于额定风速时,依据风速变化情况调整桨距角,从而使风电机组保持恒功率输出,最后在MATLAB平台上搭建仿真模型。结果表明,采用模糊PID控制比传统PID控制具有更好的动态性能和静态误差,能够优化变桨距控制方法。     

风力机功率控制器的研究

MPPT（Maxmin Power Point Tracking）控制方法在风力机功率控制器中处于核心地位,其控制策略的优劣影响整个系统的输出特性。本文构建了风力发电系统仿真模型,深入研究了风机输出特性,在此基础上对以往MPPT控制方法的改进提出自适应变步长控制策略,使其能够应用于小型风力发电系统中。     

基于MPPT的变速恒频双馈风力发电系统控制策略

充分利用风能是风力发电控制的主要目的之一,为达此目的,本文基于风力机特性和双馈风力发电机的数学模型,提出了一种不依赖于风速测量来实现双馈风力发电系统最大功率点追踪(MPPT)控制的策略。该策略应用定子磁链定向矢量控制技术,对双馈发电机进行有功功率和无功功率的解耦控制,然后通过对发电机输出有功功率进行控制来间接得到与风速相对应的最佳叶尖速比和最优转速,从而实现最大功率点追踪(MPPT)控制。仿真结果证实了基于该方法,双馈风力发电系统在风速变化过程中能自动寻找并追随最大功率点,且控制相对简单,运行可靠,有较高的实用价值。     

风电储能系统能量调度策略研究

为了改善风电场发电的稳定性,抑制风电引起的电压波动与闪变,提高含风电电力系统的稳定性问题成为重要的研究内容,本文在简要介绍风电的特点的基础上,针对风电并网带来的电能质量及稳定性等问题,阐述了基于能量调度技术的解决方案,详细介绍了基于模糊理论＂最大-最小＂算法的调度系统控制器和系统其它主要部分的模型及仿真结果。控制器根据负荷用电量预测信息控制储能系统的充放电,不仅能有效抑制并网后电网的电能波动也能优化风电的发电质量。MATLAB仿真结果表明,风电储能系统能量调度策略和控制器是有效的,该系统能够有效减小风电场并网功率的波动。     

风力发电中网侧PWM整流器的仿真研究

基于三相PWM整流器的矢量控制的原理,建立了网侧变换器所需的d-q轴模型,详细分析了风力发电系统中网侧变换器的电压电流双闭环控制原理。网侧采用了d-q模型的空间矢量脉宽调制技术(SVPWM).较好的实现了电压的跟踪和单位功率控制,整个系统可以实现整流和逆变的转换,实现能量的双向流动。仿真验证了该方案的可行性,且系统具有良好的动、静态特性。     

Wind Speed Estimation Based Sensorless Output Maximization Control for a Wind Turbine Driving a DFIG

This paper proposes a wind speed estimation based sensorless maximum wind power tracking control for variable-speed wind turbine generators (WTGs). A specific design of the proposed control algorithm for a wind turbine equipped with a doubly fed induction generator (DFIG) is presented. The aerodynamic characteristics of the wind turbine are approximated by a Gaussian radial basis function network based nonlinear input-output mapping. Based on this nonlinear mapping, the wind speed is estimated from the measured generator electrical output power while taking into account the power losses in the WTG and the dynamics of the WTG shaft system. The estimated wind speed is then used to determine the optimal DFIG rotor speed command for maximum wind power extraction. The DFIG speed controller is suitably designed to effectively damp the low-frequency torsional oscillations. The resulting WTG system delivers maximum electrical power to the grid with high efficiency and high reliability without mechanical anemometers. The validity of the proposed control algorithm is verified by simulation studies on a 3.6MW WTG system. In addition, the effectiveness of the proposed wind speed estimation algorithm is demonstrated by experimental studies on a small emulational WTG system.     

柔性交流输电系统技术在现代配电网的应用展望

本文以统一潮流控制器为例,说明了柔性交流输电技术在含有风力发电的现代配电系统中的应用前景。针对风力发电对电力系统影响的特点,指出了传统统一潮流控制器的不足,提出了将与风电配合的储能装置与统一潮流控制器相结合的拓扑原理结构,指出了基于切换系统原理的混杂PCH控制理论将有望解决底层为离散开关控制的柔性交流输电装置、上层为连...     

Fuzzy logic based intelligent control of a variable speed cagemachine wind generation system

The paper describes a variable speed wind generation system where fuzzy logic principles are used for efficiency optimization and performance enhancement control. A squirrel cage induction generator feeds the power to a double-sided pulse width modulated converter system which pumps power to a utility grid or can supply to an autonomous system. The generation system has fuzzy logic control with vector control in the inner loops. A fuzzy controller tracks the generator speed with the wind velocity to extract the maximum power. A second fuzzy controller programs the machine flux for light load efficiency improvement, and a third fuzzy controller gives robust speed control against wind gust and turbine oscillatory torque. The complete control system has been developed, analyzed, and validated by simulation study. Performances have then been evaluated in detail     

永磁直驱式变桨距风力发电机组的建模与控制

根据机组在高风速区和低风速区的特点,设计了变桨距控制系统,使得机组能够在低风速区实现最大风能跟踪。为了增强机组在复杂条件下运行特性,在高风速区采用了PID控制器。建立了机组的仿真模型,对不同风速下的机组的稳态和动态特性进行了仿真分析。仿真结果验证了采用方案和控制策略的可行性。     

Coordinated Control of DFIG's Rotor and Grid Side Converters During Network Unbalance

This paper proposes a coordinated control of the rotor side converters (RSCs) and grid side converters (GSCs) of doubly-fed induction generator (DFIG) based wind generation systems under unbalanced voltage conditions. System behaviors and operations of the RSC and GSC under unbalanced voltage are illustrated. To provide enhanced operation, the RSC is controlled to eliminate the torque oscillations at double supply frequency under unbalanced stator supply. The oscillation of the stator output active power is then cancelled by the active power output from the GSC, to ensure constant active power output from the overall DFIG generation system. To provide the required positive and negative sequence currents control for the RSC and GSC, a current control strategy containing a main controller and an auxiliary controller is analyzed. The main controller is implemented in the positive (dq)⁺ frame without involving positive/negative sequence decomposition whereas the auxiliary controller is implemented in the negative sequence (dq)^- frame with negative sequence current extracted. Simulation results using EMTDC/PSCAD are presented for a 2 MW DFIG wind generation system to validate the proposed control scheme and to show the enhanced system operation during unbalanced voltage supply.     

An intelligent maximum power extraction algorithm for inverter-based variable speed wind turbine systems

This paper focuses on the development of maximum wind power extraction algorithms for inverter-based variable speed wind power generation systems. A review of existing maximum wind power extraction algorithms is presented in this paper, based on which an intelligent maximum power extraction algorithm is developed by the authors to improve the system performance and to facilitate the control implementation. As an integral part of the max-power extraction algorithm, advanced hill-climb searching method has been developed to take into account the wind turbine inertia. The intelligent memory method with an on-line training process is described in this paper. The developed maximum wind power extraction algorithm has the capability of providing initial power demand based on error driven control, searching for the maximum wind turbine power at variable wind speeds, constructing an intelligent memory, and applying the intelligent memory data to control the inverter for maximum wind power extraction, without the need for either knowledge of wind turbine characteristics or the measurements of mechanical quantities such as wind speed and turbine rotor speed. System simulation results and test results have confirmed the functionality and performance of this method.     

Sensorless variable-speed controller for existing fixed-speed wind power generator with unity-power-factor operation

A variable-speed controller, for an existing 225 kW fixed-speed wind power generator, is presented in this paper. A sensorless direct torque control algorithm-based controller is proposed for the squirrel-cage induction generator. Generator torque reference is derived based on sensorless maximum power tracking mode algorithm, up to the base speed of the generator. A three-phase front-end converter is used here to deliver the generated power to the grid with unity-power-factor operation at all wind speeds. This algorithm is based on direct active and reactive power control. The experimental waveforms from the actual installation site are presented in this paper with a comparison of the existing fixed-speed system. An interpretation of the results is also presented here.