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变速恒频双馈风电机组最优功率控制研究
Researchon Optimal Power Control of Double-fed Wind Turbine
【作者】 刘姝;
【导师】 姚兴佳;
【作者基本信息】 沈阳工业大学 , 电机与电器, 2013, 博士
【摘要】 随着风电技术的迅速发展,保证风电机组稳定可靠运行已经不再是难题。对变速恒频双馈风电机组最优功率控制的研究逐渐成为难点和热点,引入先进的控制理论,研究具有高效率的风能转换系统控制方法,具有重要的研究价值,目前已经得到了国外很多学者的关注。本文以国家科技支撑计划的重大项目“适应海、陆环境的双馈式变速恒频风电机组的研制”课题为依托,以3MW双馈变速恒频风电机组为研究对象,对额定风速以下、额定风速以上、额定工况的过渡阶段的控制策略进行了深入的研究。其控制目标由单一化向多目标化发展,目的是通过3MW双馈风电机组的控制研究进一步最优输出功率。本文主要研究工作归纳如下:首先,根据风速具有多时间尺度的特性,基于著名学者Iulian Munteanu对风速的分析,利用风速分频原理,将风速分为稳态风速和动态风速。考虑低风速工况和高风速工况下发电机的转矩控制策略,在低风速情况时设计稳态控制器和动态控制器,目的是为了获取最大的风能以及减小电磁振荡,设计LQG最优控制器,并和PI控制器进行对比,仿真结果显示出所提出的控制方法是有效的。在高风速下为保持恒功率的输出设计了变桨稳态和动态控制器,同时将多目标的混合控制引入到稳态动态控制中,替代原有的单一目标控制,实现多目标控制策略之间的补偿,最后给出3MW风电机组的仿真分析。其次,针对风电机组在切换点附近运行时,会频繁出现切换控制回路的现象,引起风电机组的振荡,降低风电机组运行效率等问题,提出一种新型基于风速估计的前馈补偿最优功率控制策略,目的是为了在过渡阶段不同运行状态下可以迅速平滑输出功率,有效地降低风电机组的变桨距的频繁动作。通过仿真和实验,验证此策略的可行性和有效性,实验结果表明该种新型方法能够有效减小发电机输出功率波动,改善风电机组的电能质量,具有良好的控制效果。最后,在全工况下进行控制和仿真,构建3MW风电机组半实物仿真测试平台。通过模拟风电场全风况对LQG最优的动态控制、基于风速估计的前馈补偿最优功率控制策略进行了试验研究。半实物仿真平台如风轮、发电机、塔架等都用GH公司的Bladed仿真软件来模拟,而风电机组中的控制系统、传动系统、变桨机构都是应用实物来做实验,整个半实物实验台相当于完整的风电系统。根据实验结果看出,所设计的控制策略能够满足控制的需求,仿真结果和理论研究是可行的、有效的。
【Abstract】 With the rapid development of wind power in the world,the reliable and stableoperation control has been out of question.The research of optimization technology onvariable speed constant frequency wind turbine became the key and hot topic all over theworld. How to bring in advanced control theory and efficiently control the wind turbinehave been the concern for many scholars,which have significant research value.In thisdissertation,based on the major project“The developing of double-fed variable speedconstant frequency wind turbine adapt to sea and land environment”supported by nationalscience and technology,the3MW double-fed variable speed constant frequency windturbine was taken as the research object,control strategy below rated wind speed,thetransition stage and above rated wind speed control strategy had been carried out in-depthresearch. Its control objectives from a single to multi-target development,which aims tofurther optimize the output power of3MW doubly-fed wind turbine.This dissertationstudies the following issue:Firstly,Iulian Munteanu,a famous scholar,divided the wind speed into transient windspeed and steady-state wind speed,according to the multi-time multi-scale characteristicsof wind speed. Considering the low wind speed conditions and high wind speed conditionsgenerator torque control strategy,steady-state controller and transient controller aredesigned at low wind speeds,it’s purpose is obtaining the largest wind energy as well asreducing the electromagnetic oscillation.One design is based on the control of LQGoptimization and compared with the PI controller,and simulation results show that theproposed control method is effective. The other design of pitch steady-state controller andtransient controller at high wind control,which is to maintain a constant power output andto introduce multi-target hybrid control to disturbance decoupling ring control instead ofthe original single target control,can achieve compensation between the multi-objectivecontrol strategy and farthermore,achieve a goal of getting the simulation analysis of3MWwind turbine. Secondly,many problems are acitived near switch point,such as the frequencywitching between pitch control and torque control,system oscillating,wind power unitefficiency reduced and so on,a new kind of feedforward compensation power optimizationcontrol strategy based on the wind speed estimation is put forward.The purpose is transientprocess of different operation states rapidly goes and thus can effectively reduce thesystem dynamic load,and then verify the feasibility and effectiveness of this strategythrough simulation and experiment.The experimental results show that the new method,which can effectively reduce the generator output power fluctuation,has a good controleffect.Finally,the3MW wind turbine half physical test platform had been built throughwind farm wind conditions simulation. LQG optimization through the analog wind farmwind conditions the disturbance decoupling loop control optimization based on wind speedestimates feedforward compensation power control strategies are studied.In the testplatform,the rotor,generators,towers and controller are simulated with GH Bladed,drivesystem,variable pitch propellers are actual deivce. The entire semi-physical experimentsstage equivalent to complete wind power systems.The experimental results shows that thedesign of the control strategy meet the demand of wind turbine control,simulation resultsand theoretical studies are both correct and effective.
【Key words】 Wind Turbine; Wind Speed Divider; Feedforeard Compensation; LQGcontrol; Multi-target Control;