风电并网对电力系统暂态稳定的影响

发布时间：2018-02-16 13:55

本文关键词： 风电并网暂态稳定 DFIG 风电渗透率　出处：《华中科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：大规模风电并网必将在未来能源格局中占有重要的地位，当前风力发电已经在为世界电力供应做出越来越重要的贡献。但是，由于风电机组相比同步发电机结构与控制的复杂性，人们目前对含风电电力系统故障后暂态过程的认识还不是很清楚，这对于保证甚至改善含风电电力系统的暂态稳定性提出了挑战，不能够明确越来越多的风电接入系统会对系统的暂态稳定性造成怎样的影响，本文的主要工作就是探讨风电渗透率以及其他系统运行条件对含大规模风电电力系统暂态稳定性的影响。首先在明确双馈风力发电机组（DFIG）的结构以及各部分的模型与控制方法的前提下，在DIgSILENT PowerFactory中搭建了DFIG的模型，该模型含有Crowbar电路，具备低电压穿越能力。其次，将单台DFIG与某等值外部系统相连，分析了风机并网点发生故障时风机的动态行为，并与相同外部条件下同步发电机的动态行为进行了比较；详细分析了系统故障条件下风机电气与机械系统的参量变化；分析了不同故障类型对风机动态行为的影响。研究表明，○1对于暂态过程中的并网母线电压、有功功率、无功功率，DFIG对系统造成的扰动要小于同步发电机，而在故障后对电网的无功补偿、电压支撑方面，DFIG不如同步发电机；○2对于绝大多数的机械与电气指标，如机械转矩，发电机转速，桨距角，故障发生时的转子电流与发出的无功功率，故障切除时吸收的无功功率，故障过程中的并网母线电压、电磁转矩、有功输出，三相短路对DFIG造成的扰动最大，其次依次为：两相短路接地、两相相间短路、单相短路接地；○3对于故障切除时刻DFIG的有功输出与电磁转矩，两相相间短路对DFIG造成的扰动最大；对于故障切除时DFIG转子电流的变化趋势，三相短路时增加，而其他短路类型时则是减小。最后，用单台DFIG的模型等值一个由30台DFIG构成的风场，并将该风场接入三机九节点系统中，探讨了风电渗透率、风场功率因数、并网条件以及DFIG电气结构参数对系统暂态稳定性的影响。研究结果表明，○1系统发生特定故障时，减少失稳同步发电机的有功功率输出，相比减少不失稳同步发电机的有功功率输出，系统的暂态稳定性更好，并且减少的越多，系统的暂态稳定性越好；○2减小特定故障下失稳同步发电机的额定容量，系统的暂态稳定性会变差，但若与此同时减少其有功功率输出，则系统的暂态稳定性不会变差，减小特定故障下不失稳同步发电机的额定容量，不会恶化系统的暂态稳定性。
[Abstract]:Large-scale wind power grid connection is bound to play an important role in the future energy pattern. Wind power generation has been making more and more important contribution to the world power supply. Because of the complexity of structure and control of wind turbine compared with synchronous generator, the understanding of transient process of wind power system after fault is not very clear. This is a challenge to ensure and even improve the transient stability of wind power systems, and it is not clear how more and more wind power access systems will affect the transient stability of the systems. The main work of this paper is to study the influence of wind power permeability and other system operating conditions on the transient stability of wind power system with large-scale wind power. Firstly, on the premise of defining the structure, model and control method of DFG, a model of DFIG is built in DIgSILENT PowerFactory, which contains Crowbar circuit and has low voltage traversing ability. Secondly, a single DFIG is connected to an equivalent external system, and the dynamic behavior of the fan is analyzed when the fan node fails, and the dynamic behavior of the synchronous generator under the same external conditions is compared. The variation of the parameters of fan electrical and mechanical system under the condition of system fault is analyzed in detail, and the influence of different fault types on the dynamic behavior of fan is analyzed. The disturbance caused by DFIG of reactive power is smaller than that of synchronous generator, but in the reactive power compensation of power grid after failure, the voltage support of DFIG is inferior to the mechanical and electrical parameters, such as mechanical torque, for most of the mechanical and electrical indexes, such as mechanical torque. Generator speed, pitch angle, rotor current and reactive power when fault occurs, reactive power absorbed when fault is removed, grid bus voltage, electromagnetic torque, active power output during fault, The disturbance caused by three-phase short circuit to DFIG is the biggest, followed by two phase short circuit grounding, two phase short circuit, single phase short circuit earthing for the active power output and electromagnetic torque of DFIG at the time of fault removal, and the biggest disturbance to DFIG caused by two phase short circuit. For the change trend of DFIG rotor current during fault removal, the three-phase short circuit increases, while the other short circuit types decrease. Finally, the model of a single DFIG is used to equate a wind field composed of 30 DFIG, and the wind field is connected into a three-machine nine-node system, and the wind power permeability and power factor of wind field are discussed. The influence of grid connection conditions and DFIG electrical structure parameters on the transient stability of the system is studied. The results show that the active power output of the unstable synchronous generator is reduced when a particular fault occurs in the system. Compared with reducing the active power output of the unsteady synchronous generator, the transient stability of the system is better, and the more the reduction is, the better the transient stability of the system is. The transient stability of the system will become worse, but if the active power output is reduced at the same time, the transient stability of the system will not become worse, and the rated capacity of the synchronous generator without instability will be reduced, and the transient stability of the system will not deteriorate.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM614;TM712

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