双馈风电场并网系统的次同步振荡分析与抑制研究

发布时间：2019-03-19 21:28

【摘要】：随着电力系统中风电渗透率不断提升,大容量风电场并网运行将加剧系统次同步振荡的风险,不利于系统的可靠运行。本文针对双馈风电场并网系统的次同步振荡特性进行了分析研究,并利用风电机组自身灵活快速的调控能力,提出了相应的次同步振荡抑制策略。主要内容如下:(1)建立了双馈风电场并网系统的动态模型,主要包括空气动力学、传动链、双馈感应发电机、变流器控制系统以及串联电容补偿线路模型。所建立的动态模型为后文双馈风电场并网系统的次同步振荡特性分析奠定了基础。(2)采用特征值分析方法,对不同线路拓扑结构下的双馈风电场并网系统的振荡特性以及次同步振荡模态的关键影响参数进行了详细分析。针对次同步振荡模态,通过参与因子分析得到对次同步振荡模态影响最大的状态变量为转子电流,并进一步分析了影响次同步振荡模态的关键因素。分析结果表明:双馈风电机组的输入风速、转子侧变流器内环比例参数与积分参数以及线路拓扑结构均对系统的次同步振荡特性产生显著的影响。(3)针对双馈风电场并网系统存在的次同步振荡问题,提出了基于虚拟阻抗的次同步振荡抑制策略。首先,建立双馈风电场并网系统阻抗模型;其次,通过频率扫描与奈奎斯特稳定判据分析转子侧变流器不同控制参数下系统的稳定性,并与特征值分析结果对比,验证了阻抗模型的正确性;然后,基于阻抗模型给出详细的虚拟阻抗控制器的设计方法,通过奈奎斯特稳定判据与伯德图对控制器抑制效果进行分析;最后,通过时域仿真详细对比了附加不同性质的控制器的抑制效果,验证了虚拟阻抗控制器可以最好的抑制系统的次同步振荡。(4)鉴于双馈风电场并网系统参数辨识容易存在偏差,变流器相关的控制参数也难以准确获得,提出了基于转子电流移相平均的次同步振荡抑制策略。在分析转子电流成分的基础上,通过对转子电流进行移相与取平均值处理以达到快速平抑系统次同步振荡的作用。时域仿真验证了所提抑制策略的有效性以及对量测频率误差具有较好的鲁棒性。论文所做的理论研究和仿真结果表明:采用特征值分析方法对双馈风电场并网系统次同步振荡进行分析,有利于准确揭示系统的运行特性;利用双馈风电机组自身的灵活控制特性设计有效的控制器,能够实现系统次同步振荡的快速抑制,为含大容量风电场的电力系统的安全稳定运行提供重要的理论支撑。
[Abstract]:With the increasing permeability of wind power in power system, large-capacity wind farm grid-connected operation will aggravate the risk of sub-synchronous oscillation of the system, which is not conducive to the reliable operation of the system. In this paper, the sub-synchronous oscillation characteristics of doubly-fed wind farm grid-connected system are analyzed and studied, and the corresponding subsynchronous oscillation suppression strategy is put forward by utilizing the flexible and fast regulating ability of wind turbine itself. The main contents are as follows: (1) the dynamic model of doubly-fed wind farm grid-connected system is established, including aerodynamics, transmission chain, doubly-fed induction generator, converter control system and series capacitor compensation circuit model. The established dynamic model lays a foundation for the analysis of the sub-synchronous oscillation characteristics of the doubly-fed wind farm connected to the grid. (2) the eigenvalue analysis method is used to analyze the sub-synchronous oscillation characteristics of the double-fed wind farm. The oscillation characteristics of doubly-fed wind farm connected to the grid under different line topologies and the key parameters of sub-synchronous oscillation modes are analyzed in detail. For the sub-synchronous oscillation mode, the state variable which has the greatest influence on the sub-synchronous oscillation mode is the rotor current by participating factor analysis, and the key factors affecting the sub-synchronous oscillation mode are further analyzed. The analysis results show that the input wind speed of doubly-fed wind turbine, The proportional and integral parameters of the rotor side converter inner loop and the topology structure of the line have significant effects on the sub-synchronous oscillation characteristics of the system. (3) for the doubly-fed wind farm grid-connected system, the sub-synchronous oscillation problem exists. A subsynchronous oscillation suppression strategy based on virtual impedance is proposed. Firstly, the impedance model of grid-connected doubly-fed wind farm is established. Secondly, the stability of the rotor side converter under different control parameters is analyzed by frequency scanning and Nyquist stability criterion, and compared with the results of eigenvalue analysis, the correctness of the impedance model is verified. Then, based on the impedance model, a detailed design method of virtual impedance controller is given, and the suppression effect of the controller is analyzed by Nyquist stability criterion and Bird diagram. Finally, the suppression effects of additional controllers with different properties are compared in detail by time domain simulation. It is verified that the virtual impedance controller can best suppress the sub-synchronous oscillation of the system. (4) since the parameter identification of the doubly-fed wind farm connected to the grid system is prone to deviation, the relevant control parameters of the converter are difficult to be obtained accurately. A subsynchronous oscillation suppression strategy based on phase-shift averaging of rotor current is proposed. On the basis of analyzing the components of rotor current, the sub-synchronous oscillation of the system can be quickly suppressed by phase-shifting and average-value treatment of rotor current. The time domain simulation results show that the proposed suppression strategy is effective and robust to the measurement frequency error. The theoretical research and simulation results show that using eigenvalue analysis method to analyze the sub-synchronous oscillation of doubly-fed wind farm grid-connected system is beneficial to accurately reveal the operating characteristics of the system. By using the flexible control characteristics of doubly-fed wind turbines, an effective controller is designed, which can quickly suppress the sub-synchronous oscillation of the system and provide an important theoretical support for the safe and stable operation of the power system with large capacity wind farms.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM614;TM712

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