随着风力发电技术的快速发展，双馈型风机得到了广泛应用。由其组成的大规模风电场并网后对电力系统的影响引起了广泛关注。本文针对其中的两个关键问题：双馈型风电场并网后对电力系统小扰动稳定的影响和含风电场并网的电力系统优化运行进行了系统、深入的研究。主要成果归纳如下：建立了双馈型风电场的实用机电暂态模型。在风轮机建模中根据是否考虑风速变化建立了风机输出功率恒定模型和多项式模型；在双馈型发电机建模中，引入了定子磁链定向控制策略；在换流器建模中，在定子磁链定向控制的基础上，将其等效为电压控电流源，实现定子有功、无功功率解耦控制。在完成了单台风机建模的基础上，采用等值风机的方法建立了双馈型风电场的等效模型。从风电场并网后对电力系统影响的角度出发，对含风电场并网的电力系统的小扰动稳定性和机电振荡进行了研究。以IEEE 3机9节点和IEEE新英格兰10机39节点系统为算例，考虑风电场取代同步发电机并网和风电场直接并网两种方式，分析了风电场并网后对电力系统小扰动稳定性和机电振荡的影响。研究了计及风力发电间歇、波动性的电力系统小扰动稳定分析。应用基于蒙特卡洛模拟的概率小扰动分析方法，从风速的概率分布出发，对风电场出力和系统特征根的概率分布进行求解。并通过考虑风力发电出力渐变的特征根轨迹分析，研究了电力系统小扰动稳定性和机电振荡随风电场出力的变化情况。从系统备用容量使用和环境效益角度出发，提出一种新的风电场预期出力机会成本模型，在此基础上建立了一个更为全面、计及稳定约束的含风电场并网的电力系统最优潮流数学模型。并提出采用自适应进化规划方法来求解该优化问题。在算例仿真中讨论了风电场接入位置的选择和小扰动稳定约束的影响。研究了含风电场并网的电力系统多目标优化运行问题。以发电成本最小，有害气体排放最少以及线路有功损耗最低三个目标为目标函数，建立了一个更为全面、实用的计及风电场发电费用的电力系统多目标优化模型。提出采用理想点法进行求解，并讨论了小扰动稳定约束对多目标优化结果的影响。

With the fast development of wind generation technology, the wind turbine equipped with DFIG(Double-fed Induction Generator) is widely used around the world. Particularly, with the application of large-scale grid-connected wind farms of DFIG type, the corresponding impacts on the existing power system have gotten the attention and interest of power system engineers and researchers. This thesis mainly focuses on two key issues with respect to the grid connection of wind farm: the impact of large-scale wind farm of DFIG type on power system small signal stability and the optimal operation of power system with large-scale wind farm connected. The main achievements are as follows:A simplified practical electro-mechanical model of wind farm of DFIG type is developed in this thesis. Two kinds of wind turbine models including the constant mechanical input and a function approximation are established according to whether the wind speed change is considered during modelling. The stator-flux-oriented control strategy is applied in the modelling of DFIG. As for the modelling of DFIG converters, based on the stator-flux-oriented control strategy, the rotor-side converter is modelled as a voltage-controlled current source to implement the decoupled control of stator real and reactive power outputs. After the modelling of single wind turbine equipped with DFIG, the modelling of wind farm is to assume an equivalent macro-wind generator. The small signal stability analysis of power system with large-scale grid-connected wind farm of DFIG type is systematically conducted in this thesis. Two test systems involving IEEE 3-Generator-9-bus test system and IEEE New England test system are employed as benchmark to explore and exploit the impact of grid-connected wind farm of DFIG on the small signal stability and the electromechanical oscillations. Two ways of wind farm connection including the replacement of synchronous generator by wind farm at specific bus and the direct connection are elaborately considered during simulations. The power system small signal stability analysis considering the intermittent and fluctuant characteristics of wind power is comprehensively studied in this thesis. In accordance with the Weibull distribution of wind speed, the Monte Carlo simulation technique based probabilistic small signal stability analysis is applied to solve the probability distributions of wind farm power output and the eigenvalues of the state matrix. Furthermore, the relationship between the change of wind power output and the small signal stability is studied based on the analysis of eigenvalue trajectory with gradually increasing wind power output. In the points of power system reserve capacity and environment benefits, a novel wind farm anticipated power opportunity cost model is proposed in this thesis. Based on the proposed wind farm cost model, a more comprehensive and practical optimal power flow (OPF) model with small signal stability constraint involved is established. The self-adaptive evolutionary programming is employed to solve the optimal problem. The issue of the different positions of connection to the power grid for a wind farm is discussed during numerical simulations. And the impacts of grid-connected wind farm on the OPF with consideration of small signal stability constraint are investigated as well. A multi-objective power system optimal operation model considering wind generation cost is presented in this thesis. Total 3 objectives including generation cost, transmission losses and environmental pollution are considered during modelling. The ideal point method is applied to make the multi-objective problem a single objective problem. Finally, the case studies are elaborately conducted to reveal the impact of grid-connected wind farm on power system optimal operation with consideration of small signal stability constraint.