基于阻抗分析法的双馈风力发电机系统稳定性研究

发布时间：2018-08-26 06:50

【摘要】：作为在地球上存储量巨大、可以清洁利用的可再生能源,风能的开发是新能源发电领域重要的研究内容。双馈式风力发电机是目前使用最多的风力发电机组类型之一。受电网条件与自身控制系统的交互影响,双馈电机在并网发电过程中会出现各类稳定性问题。因此,本文采用阻抗分析的方法针对双馈风力发电机与各种条件电网的连接系统的稳定性展开研究工作,主要研究内容包括:建立双馈电机二阶矩阵形式与复矢量形式的等效导纳模型、应用阻抗分析方法分析双馈电机在弱电网条件下的稳定性和使用改变双馈电机导纳特性的方法抑制串补条件下发生的次同步振荡问题。应用阻抗分析方法进行双馈电机与电网连接系统的稳定性分析是本文的主要研究内容。本文建立了考虑双馈电机定、转子磁链暂态以及转子侧变流器电流环、锁相环、有功功率外环以及交流电压幅值外环的双馈电机等效输入导纳模型,并通过频率扫描的方法在仿真中测量双馈电机的等效输入导纳验证推导出的模型的正确性。建立弱电网、串补条件下的线路阻抗模型,结合推导的双馈电机等效导纳模型,依据广义奈奎斯特稳定性判据分析系统的稳定性。考虑到在两相旋转坐标系下建立的双馈电机导纳模型是二阶矩阵形式,在进行稳定性分析时需要使用针对多输入多输出系统的广义奈奎斯特稳定性判据,分析过程相对复杂,本文建立了考虑锁相环控制器的复矢量形式的双馈电机等效导纳模型。使用复矢量形式的模型根据奈奎斯特稳定性判据进行系统的稳定性分析,可以简化分析过程。针对串补条件下双馈系统可能发生的次同步振荡问题,本文使用了改变双馈电机等效输入导纳特性的抑制方法。当次同步振荡问题发生时,在转子侧控制器中加入滤波器改变双馈电机在次同步频率范围内的导纳特性。该方法不需要额外的设备,较容易实现,且能够有效地抑制次同步振荡问题。在实验室的双馈平台上完成了弱电网条件下双馈系统稳定性分析的实验验证。
[Abstract]:As a renewable energy with huge storage capacity and clean utilization, wind energy development is an important research content in the field of new energy generation. Doubly-fed wind turbine is one of the most widely used wind turbine generators. Due to the interaction between the power system and its own control system, various stability problems will occur in the grid-connected generation process of the doubly-fed generator. Therefore, the impedance analysis method is used to study the stability of the connection system between the doubly-fed wind turbine and the power grid under various conditions. The main research contents are as follows: the equivalent admittance models of second-order matrix form and complex vector form of doubly-fed machine are established. The method of impedance analysis is used to analyze the stability of a doubly-fed machine under the condition of weak electric net and the method of changing the admittance characteristic of the double-fed machine is used to suppress the sub-synchronous oscillation under the condition of series compensation. The stability analysis of doubly-fed motor and grid connection system using impedance analysis method is the main content of this paper. In this paper, an equivalent input admittance model of a doubly-fed machine considering stator, rotor flux chain transient and rotor side converter current loop, phase-locked loop, active power outer loop and AC voltage amplitude outer loop is established. The equivalent input admittance of the doubly-fed machine is measured by frequency scanning method to verify the correctness of the derived model. The line impedance model under the condition of weak electric network and series compensation is established. Combined with the equivalent admittance model of doubly-fed machine, the stability of the system is analyzed according to the generalized Nyquist stability criterion. Considering that the admittance model of doubly-fed machine established in two-phase rotating coordinate system is a second-order matrix form, the generalized Nyquist stability criterion for multi-input and multi-output systems is needed in the stability analysis, and the analysis process is relatively complex. In this paper, an equivalent admittance model of a doubly-fed machine considering the complex vector form of a phase-locked loop controller is established. Using the complex vector model to analyze the stability of the system based on Nyquist stability criterion can simplify the analysis process. In order to solve the problem of subsynchronous oscillation in doubly-fed system under series-compensated condition, a method to reduce the equivalent input admittance characteristics of doubly-fed system is proposed in this paper. When the sub-synchronous oscillation problem occurs, a filter is added to the rotor side controller to change the admittance characteristics of the doubly-fed machine in the sub-synchronous frequency range. The method is easy to implement without additional equipment and can effectively suppress the subsynchronous oscillation problem. The experimental verification of the stability analysis of the doubly-fed system under the condition of weak electric net is carried out on the double-fed platform in the laboratory.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM315

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