风电场并网对电力系统电压稳定性的影响

发布时间：2018-03-08 13:22

本文选题：风电并网　切入点：静态电压稳定性　出处：《山东大学》2016年硕士论文　论文类型：学位论文

【摘要】：能源危机和环境恶化已经日益威胁人类社会的安全和发展,为此,世界各国都在积极寻找开发新能源。作为新能源的一种,风能的储量非常丰富,且便于开发,用风能进行发电清洁无污染,值得大力提倡,因此,近些年来世界各国都在大力开发风能进行发电。但由于风能具有间歇性和随机性,风力发电的可控性较差,随着风电场并网规模的逐渐增加,风电接入对电网的影响不断增加,尤其是对电网电压稳定性的影响更为突出,鉴于此,本文对该课题进行了深入的研究。随着风电机组的发展,双馈异步风力发电机凭借其较高的性价比逐渐成为目前风电场中的主流风机,本文中详细的介绍了双馈机组的稳态模型,并在此基础上推导出了在输出一定有功功率的条件下机组并网系统所能输出无功功率极限的表达式。在潮流计算过程中,由双馈异步风机组成的风电场可以根据风电机组控制方式以不同等值模型的形式接入系统,并且随着机组输出有功功率的改变,风电场的等值模型还可能会发生改变。本文主要采用基于一般潮流解的局部电压稳定性指标(L指标)对风电并网前后电网的静态电压稳定性进行分析：系统中某节点的L指标越大,证明该节点静态电压稳定程度越薄弱,且更易发生电压失稳。基于L指标,本文还推导出了一种衡量系统中风电场输出有功功率的改变对各节点L指标影响程度的L-P灵敏度指标,通过对该指标进行排序,能够得到与风电场节点相关性较强的节点,同时,L-P灵敏度指标值还可以被用来预估风电注入有功功率增加或减小时,可能会对系统各节点的L指标值产生的影响。以上两种指标结构简单,计算速度快,均可用于在线电压稳定分析。接下来,本文利用基于一般潮流解的L指标和L-P灵敏度指标,对风电并网前后的IEEE 39节点系统进行静态电压稳定分析,分别改变风电场的注入有功功率和并网线路参数及其风电场中双馈机组的机组控制方式,比较不同条件下系统的风电场并网节点L指标的变化规律。并运用相关的理论知识,给出合理的解释并得出结论,这对大规模风电场的并网运行具有实际的指导意义。最后以山东烟台威海实际系统为算例,对该地区风电场接入的影响做出探讨。首先,在各个风电场额定输出范围内：分别在风电场出力不同的条件下计算接入母线电压和L指标的变化情况,以此来判断风电并网的利弊；通过计算风电场满发时各并网母线对风电场注入有功的L-P灵敏度指标判断该地区风电场扩容的可行性。接下来,本文还探究了系统运行方式的改变和风电场中机组控制方式的不同所带来的风电并网对系统电压稳定性影响的改变。最后,本文提出了几种减小风电并网带来的电压波动、增强并网后系统电压稳定性的措施,特别的,对风电场的就地无功补偿方式做了重点介绍。
[Abstract]:The energy crisis and environmental deterioration have threatened the security and development of human society day by day. For this reason, every country in the world is actively seeking to develop new energy. As a new energy source, wind energy reserves are very rich and easy to develop. The clean and pollution-free use of wind power is worth advocating. Therefore, in recent years, all countries in the world have been vigorously developing wind energy to generate electricity. However, due to the intermittent and random nature of wind energy, the controllability of wind power generation is poor. With the increasing scale of wind farm connection, the influence of wind power access on power grid is increasing, especially on the voltage stability of power grid. With the development of wind turbine, doubly-fed asynchronous wind turbine has become the mainstream fan in wind farm by virtue of its high performance-to-price ratio. In this paper, the steady-state model of doubly-fed generating unit is introduced in detail, and the expression of the limit of reactive power output by the grid-connected system under certain active power output is derived on the basis of this model. In the process of power flow calculation, A wind farm composed of a doubly-fed asynchronous fan can access the system in the form of different equivalent models according to the control mode of the wind turbine, and with the change of the active power output of the unit, In this paper, the local voltage stability index based on the general power flow solution is used to analyze the static voltage stability of the wind power grid before and after the wind power grid connection. The greater the L index of the node, It is proved that the weaker the static voltage stability of the node is, the more vulnerable it is to voltage instability. This paper also deduces an L-P sensitivity index to measure the influence of the change of the active power output of wind farm on the L index of each node. By sorting the index, the nodes with strong correlation with the wind farm node can be obtained. At the same time, the L-P sensitivity index value can also be used to predict the increase or decrease of active power injected into wind power, which may have an effect on the L index value of each node of the system. The above two indexes are simple in structure and fast in calculation. All of them can be used for on-line voltage stability analysis. Then, the static voltage stability analysis of IEEE 39-bus system before and after wind power grid connection is carried out by using L index and L-P sensitivity index based on general power flow solution. The injected active power of wind farm and the parameters of grid-connected line and the control mode of doubly-fed unit in wind farm are changed respectively, and the variation law of L index of connected node of wind farm under different conditions is compared, and the relevant theoretical knowledge is used. The reasonable explanation is given and the conclusion is drawn that it has practical guiding significance for the grid connection operation of large-scale wind farm. Finally, taking the actual system of Weihai in Yantai, Shandong Province as an example, the influence of wind farm connection in this area is discussed. In the range of rated output of each wind farm: under the condition of different output force of wind farm, the change of access bus voltage and L index are calculated respectively, so as to judge the advantages and disadvantages of wind power grid connection; The feasibility of wind farm expansion in this area is judged by calculating the L-P sensitivity index of the active power injected into the wind farm by each grid bus when the wind farm is full. This paper also discusses the change of system operation mode and the influence of wind power grid connection on system voltage stability caused by different control modes of wind farm. Finally, this paper proposes several methods to reduce the voltage fluctuation brought by wind power grid connection. The measures to enhance system voltage stability after grid connection are introduced, especially, the local reactive power compensation mode of wind farm is introduced emphatically.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM712;TM614

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