双馈风力发电机低电压穿越相关问题研究

发布时间：2018-09-08 18:23

【摘要】：近年来,风电容量比例逐年增加。当电网故障发生时,风力发电机组大规模脱网运行将会加剧故障程度。为了保证电力系统的安全稳定运行,许多国家对风场接入电网提出了低电压穿越的要求。双馈风力发电机(DFIG)具有能量利用率高、转速可变、风机机械应力低、变流器容量及成本低等优点,因而成为当前最为广泛应用的风电机型之一。但同时因其变流器容量较低,并且对电网故障尤其是电压跌落十分敏感,因此对低电压穿越能力要求特别高。本文在介绍DFIG基本原理的基础上,建立了其在三相静止坐标系和同步旋转坐标系下的数学模型。分别对转子侧变流器的定子磁链定向和网侧变流器的电网电压定向矢量控制策略进行了研究,并在Matlab/Simulink中搭建了仿真模型。本文重点分析了电网故障时DFIG的动态特性。从定子磁链和转子开路电压出发,分析了各类电网故障对DFIG动态特性的影响。分析和比较了不同跌落程度下的同类故障,对称故障与不对称故障以及计及相角跳变与否时DFIG的不同动态响应。从理论上推导了故障时的动态响应,并通过仿真进行了验证。本文还对广泛使用的基于撬棒(Crowbar)电路的DFIG低电压穿越策略展开了研究。主要分析了Crowbar电路电阻阻值的整定范围,推导得出了阻值大小对于故障后稳态下DFIG电磁转矩和吸收无功的影响。仿真结果验证了上述研究,为工程上选择合适的Crowbar电路电阻阻值提供了借鉴。
[Abstract]:In recent years, the proportion of wind capacity increases year by year. When the power grid fault occurs, the large-scale de-grid operation of wind turbine will aggravate the fault degree. In order to ensure the safe and stable operation of power system, many countries put forward the requirement of low voltage traversing for wind field connecting to power grid. Doubly-fed wind turbine (DFIG) has the advantages of high energy utilization, variable rotational speed, low mechanical stress of fan, low capacity and low cost of converter, so it has become one of the most widely used wind power models. But at the same time because of its low capacity and sensitive to power network faults especially voltage sag the capacity of low voltage traversing is very high. Based on the introduction of the basic principle of DFIG, the mathematical models of DFIG in three phase stationary coordinate system and synchronous rotating coordinate system are established. The stator flux orientation of the rotor side converter and the voltage oriented vector control strategy of the grid side converter are studied, and the simulation model is built in Matlab/Simulink. In this paper, the dynamic characteristics of DFIG are analyzed. Based on stator flux chain and rotor open circuit voltage, the influence of various power grid faults on dynamic characteristics of DFIG is analyzed. The different dynamic responses of DFIG are analyzed and compared under the condition of the same kind of fault, symmetric fault and asymmetric fault, and considering the phase angle jump or not. The dynamic response of the fault is deduced theoretically and verified by simulation. The low voltage traversing strategy of DFIG based on crowbar (Crowbar) circuit is also studied in this paper. The setting range of resistance of Crowbar circuit is analyzed, and the influence of resistance value on DFIG electromagnetic torque and absorbing reactive power under steady state after failure is deduced. The simulation results verify the above research and provide a reference for selecting appropriate resistance of Crowbar circuit in engineering.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM315

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