【作者】 李晓蕾；

【导师】 刘宪林；

【作者基本信息】 郑州大学 ， 电力系统及其自动化， 2003， 硕士

【摘要】 随着“西电东送”工程的建设投运和全国互联电力系统的逐步形成，电力系统的小扰动稳定问题更加突出，而当前电力系统小扰动稳定研究水平还不能很好地适应电力系统规模扩大和稳定分析与控制水平提高的要求。研究既可满足系统规模要求、又有较高分析计算精度的多机电力系统小扰动稳定降阶分析方法，具有重要的学术研究价值和工程现实意义。本文在回顾分析电力系统小扰动稳定研究的发展历程及其研究现状的基础上，开展了基于详细模型的多机电力系统小扰动稳定降阶分析方法的研究工作。 为解决特征值QR算法的维数局限与电力系统规模以及模型精度之间的矛盾，本文提出了多机电力系统特征值降阶计算的模糊分块解耦法。该方法根据多机电力系统的机电耦合特性，在多机系统同步力矩系数矩阵的基础上，求取传递闭包，通过选择适当的阈值水平α，实现多机系统的合理分块解耦；对各分块解耦子系统分别计算特征值，各子系统的特征值的集合可以近似作为原多机系统的特征值。这一方法可以控制分块解耦子系统的规模，实现多机系统特征值的降阶计算，避免特征值QR算法的“维数灾难”，同时为采用计及发电机阻尼绕组作用的详细模型计算大型电力系统的全部特征值、提高电力系统小扰动稳定分析的准确性提供了一种方法。对模糊分块解耦法可能出现的伪复根现象进行分析，认为伪复根是将原本存在机电耦合的子系统强行解耦导致特征值“变异”的一种现象，一般不会影响小扰动稳定分析的结果。 基于传统等效二阶模型的选择模式分析法，虽然实现了多机系统机电模式的降阶计算，但存在着计算精度不高和特征根“丢失”现象。本文利用基于发电机详细描述的多机系统精确等效二阶模型，提出了模糊分块解耦法与选择模式分析法相结合的机电模式计算方法。这一方法由模糊分块解耦法提供准确度较高的全部机电模式的初值，再由选择模式分析法迭代求出准确的机电模式。这种基于精确等效二阶模型的多机系统机电模式计算方法，一方面有效地避免了采用传统矩阵法提供机电模式迭代初值时存在的特征值“丢失”现象，另一方面提高了机电模式的计算精度。 频域分析法在多机系统小扰动稳定方面的研究尚没有达到工程实用的要求。为探索解决这一问题，本文基于多机电力系统小扰动稳定分析的完全解耦法，将多机系统完全解耦模型与频域分析法相结合，从三个方面实现了多机系统小扰动稳定的频域降阶分析：籍助各解耦单机系统的开环频率特性曲线和开环频域性能—郑竺州达堂工堂鱼土遮义一一一一一一一一一一一一一一一一一标直观地分析多机系统的绝对稳定性和相对稳定性;籍助各解祸单机系统的闭环系统特征多项式频率特性，计算各解祸单机系统的闭环主导极点近似值并迭代求解其准确值，获取多机系统的机电模式;运用复数力矩系数法，计算各解祸单机系统的同步力矩系数和阻尼力矩系数，这对于分析机组间的祸合状况判断机组失稳原因具有直接的意义。 作者编制了实现上述多机电力系统小扰动稳定三种降阶分析方法的MATLAB程序。更多还原

【Abstract】 With the building and operation of the project "electric power transmission from west to east" and the forming of the nationwide power system’s inter-connection, the problem of power system small signal stability is more notable. The research standard on the small signal stability cannot adapt to the needs that are propitious to the enlarging scale of power system and the levels of stability analysis and control. To study the reduced-order analysis methods that not only can satisfy the need of the system scale but also have higher calculation precision has an important academic value and practical project sense. Based on the review and present tendency analysis for small signal stability research, in this thesis, the reduced-order analysis method for small signal stability of multi-machine power system using detail model is researched.In order to settle the contradiction among the dimension localization of QR, scale of power system and the precision of the models, in this thesis, a fuzzy block-decoupling method is brought forward to calculate the eigenvalues of multi-machine power system. This method realizes the reducing order calculation. Based on the electromechanical coupling characteristic of the multi-machine power system, the transitive closure is calculated depending on the synchronization torque coefficient matrix. Then a proper threshold value is chosen to achieve the reasonable block decoupling of multi-machine power system. Eigenvalues of block-decoupling subsystem are calculated respectively. The set of these eigenvalues can be regarded as the eigenvalues of primary system approximately. This method not only can control the scale of the block-decoupling subsystems, but also achieves the reduced-order eigenvalue calculation for multi-machine power system. So this method can avoid the dimension disaster in the QR and calculate all the eigenvalues of large power system with the effect of damping windings considered. Through analyzing the phenomenon of the pseudo complex value in the block-decoupling method, the pseudo complex value is considered as the result of eigenvalue variation because of the system being decoupled forcedly, but this phenomenon has no effect on the result of the small signal stability.The selective modal analysis method (SMA) based on the tradition equivalence second-order model achieves the reduced-order calculation for the electromechanical modes, but its calculation precision isn’t higher and sometimes it may lose eigenvalues.Based on the exact equivalence second-order model of multi-machine using detailmodel of generator, an electromechanical calculation method is put forward. This method connects the fuzzy block-decoupling method and the selective modal analysis method. Firstly, all the electromechanical initial values with higher accuracy are provided by the fuzzy block-decoupling method, and then the exact eigenvalues are iterated by the selective modal analysis method. This method can not only avoid losing eigenvalues but also improve the calculational precision of electromechanical modes.The method of frequency domain analysis doesn’t reach the applied requirement for project in the small signal stability of multi-machine power system. In order to settle this problem, in this thesis, the complete decoupling method for the small signal stability of multi-machine power system connects the complete decoupling model of multi-machine power system with the frequency domain analysis method to achieve the reduced-order analysis in frequency domain from three ways. The absolute and relative stability of multi-machine is analyzed intuitionally using the open-loop frequency characteristic charts and the performance index of open-loop frequency domain for each decoupling single-machine. The closed-loop main poles of each single-machine are attained approximately from the characteristic polynomial frequency characteristic of closed-loop system of each decoupling single-machine, and its exact value can be computed using iteration. In general, these values just are the更多还原