大规模风电经串补送出引起的次同步振荡机理分析

发布时间：2019-03-29 13:47

【摘要】：我国地域辽阔,能源资源分布与负荷发展极不平衡。近年来,风电场的建设容量大幅度提升,大规模的风电建设与并网运行,为解决能源危机和消纳问题提供解决方案。然而,风力发电主要以串联补偿和风火打捆的形式进行输送功率。第一种外送方式下可能存在次同步振荡的威胁,第二种方式下,原有同步发电机系统的阻尼特性也可能引发振荡现象。近些年,相关工作者将次同步振荡问题进行了分类,提出风电场与串补输电系统在次同步频率范围内发生能量转换的一种相互作用现象,称为风电场次同步振荡(Sub-synchronous Oscillation,SSO),包含次同步谐振(Sub-synchronous resonance,SSR)、在次同步频率下快速响应的风电机组控制器与轴系相互作用引发的次同步扭矩相互作用(Sub-synchronous control,SSTI)、风电机组控制器与固定串补系统引发的次同步控制相互作用(Sub-synchronous control interaction,SSCI)三方面。本文针对大型风电场经固定串补外送功率引发的次同步振荡现象,首先以双馈风电机组作为研究对象,建立适用于SSO分析的DFIG系统模型,其中包括汽轮机扭矩轴系、双馈感应发电机、串补输电线路以及换流器控制系统的数学模型,然后通过小信号分析法对上述模型进行建模,求出线性化系统方程的系数矩阵,并计算矩阵的特征值与特征向量,得到不同振荡模态下的频率,采用特征值分析法分析各个振荡模态下所对应状态变量的参与因子程度。然后通过MATLAB/Simulink仿真平台建立时域仿真模型,对上述所建系统的有效性进行验证,并分析系统参数以及换流器控制器的内部参数对SSO的阻尼比影响关系,进而分析出对SSO的阻尼特性。研究结果显示:串补度增大、风电机组容量增大、风速减小、转子侧换流器(Rotor side converter,RSC)控制器内环参数增大都会使得SSO显著增强,并且证明RSC外环参数对SSO特性影响并不显著。最后,建立有功功率-转速和无功功率-转速的传递函数,进而求解出各自所能提供正阻尼的相位角区域,然后建立目标函数,通过遗传算法求解PID相位补偿的传递函数参数,建立出有功-转速和无功-转速环的优化控制策略。时域仿真验证该策略能在全频带范围内向系统提供正阻尼,且无功-转速环附加阻尼控制策略更优。
[Abstract]:China's vast territory, the distribution of energy resources and load development is extremely unbalanced. In recent years, the construction capacity of wind farms has been greatly increased, and large-scale wind power construction and grid-connected operation provide solutions for solving energy crisis and consumption problems. However, wind power generation is mainly carried out in the form of series compensation and wind-fire bundling. In the first mode, there may be the threat of subsynchronous oscillation, and in the second mode, the damping characteristics of the original synchronous generator system may also cause the oscillation phenomenon. In recent years, the problem of sub-synchronous oscillation has been classified by relevant workers, and a kind of interaction phenomenon between wind farm and series compensation transmission system in the range of sub-synchronous frequency has been put forward, which is called wind power field sub-synchronous oscillation (Sub-synchronous Oscillation,). The SSO), includes the secondary synchronous resonance (Sub-synchronous resonance,SSR), the secondary synchronous torque interaction (Sub-synchronous control,SSTI) caused by the interaction between the wind turbine controller and the shafting at the sub-synchronous frequency. There are three aspects of subsynchronous control interaction (Sub-synchronous control interaction,SSCI) between wind turbine controller and fixed series compensation system. In this paper, according to the phenomenon of sub-synchronous oscillation caused by fixed series compensation output power in large-scale wind farm, firstly, the doubly-fed wind turbine is taken as the research object, and the DFIG system model suitable for SSO analysis is established, including turbine torque shaft system. The mathematical models of doubly-fed induction generator, series compensation transmission line and converter control system are established. Then the model is modeled by small signal analysis, and the coefficient matrix of linearized system equation is obtained. The eigenvalues and Eigenvectors of the matrix are calculated and the frequencies under different oscillation modes are obtained. The participation factors of the corresponding state variables under each oscillation mode are analyzed by the eigenvalue analysis method. Then the time-domain simulation model is established through MATLAB/Simulink simulation platform to verify the effectiveness of the above-mentioned system and analyze the relationship between the system parameters and the internal parameters of the converter controller on the damping ratio of the SSO. Furthermore, the damping characteristics of SSO are analyzed. The results show that the increase of series compensation, the increase of wind turbine capacity, the decrease of wind speed, and the increase of inner ring parameters of rotor side converter (Rotor side converter,RSC) controller will significantly enhance the SSO. It is also proved that the influence of RSC outer ring parameters on SSO characteristics is not significant. Finally, the transfer functions of active power-speed and reactive power-speed are established, and then the phase angle regions which can provide positive damping are solved. Then the objective function is established, and the transfer function parameters of PID phase compensation are solved by genetic algorithm. The optimal control strategy of active power-speed loop and reactive-power-speed loop is established. The time domain simulation shows that the proposed strategy can provide positive damping to the system in the full band range, and the additional damping control strategy of reactive power-speed loop is better than that of the control strategy.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM614;TM712

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