【作者】 张建芬；

【导师】 王克文；

【作者基本信息】 郑州大学 ， 电力系统及其自动化， 2004， 硕士

【摘要】 在电力系统运行过程中，存在着许多随机扰动或不确定因素，例如节点注入功率或网络结构的变化，以及测量和估计误差。概率特征根分析和电力系统稳定器设计方法可以更多地计及不确定因素，维持系统在较宽运行条件下的稳定性。而概率潮流计算又为概率特征根分析提供了发电机的初始状态和节点电压的均值和协方差。本文在现有概率分析方法的基础上，进行概率潮流计算的误差比较和算法改善、概率特征根算法改进，以及概率控制器参数优化。 在现有的保留二阶项的概率潮流算法中，节点电压取直角坐标形式，均值和方差交替求解，计算节点功率均值时计及了电压协方差对功率均值的修正作用，但对节点电压协方差的计算采用了线性化模型。分析发现，计算结果中，电压的均值和实际值相当接近，而电压的协方差却有较大的差别，尤其是与电压实部有关的协方差值差别更大。本文基于节点注入和PV电压运行曲线，将雅可比矩阵进行扩展，以便计及平衡点的电压曲线；不仅在节点注入均值中考虑电压协方差的修正，在计算电压协方差时也充分考虑了节点注入和电压的非线性关系。将所用算法与已有的线性化概率潮流模型和近似二阶模型在迭代算式和计算精度方面进行了比较。结果表明，所用的完整二阶模型能够提供相当满意的电压均值和协方差。 在概率特征根分析方面，分析比较了几种模型的计算精度，包括线性化模型、简化二阶模型、完整二阶模型和修正系数矩阵A，以及高阶累加量法。通过在两个系统上的计算分析表明，简化二阶模型的计算精度尚可以接受，虽然仍存在着一定的误差；完整二阶模型的计算精度并没有提高，却需要较多的计算时间；修改系数矩阵模型和对节点注入做线性变换求取特征根累加量的方法效果不稳定，即随算例而变化。 在PSS参数设计方面，利用概率灵敏度指标，进行PSS的最佳位置选择，结合相位补偿概念进行初始参数设计，并利用非线性规划技术进行参数优化。目标函数中计及了不满足稳定条件的所有特征根的性能指标。最后在八机系统上分别考查了基于单运行方式和多运行方式下优化方法的收敛特性。结果表明，利用非线性规划技术可以进一步协调PSS参数。更多还原

【Abstract】 In power system operation, there are many fluctuations and random factors, such as the variations of load powers and generations, changes in network configuration and system parameters, as well as the measure and forecast errors. In order to improve the stability of power systems in more wide operating condition, the probabilistic technique has been adopted to eigenvalue analysis and power system stabilizer (PSS) design. The initial operating state of generators and the probabilistic attributes of nodal voltages are determined by the probabilistic load flow computation. Based on the present probabilistic analysis methods, some works have been carried out in this thesis, including the computational error comparison and the algorithm improvement for probabilistic load flow; the analysis and improvement for probabilistic eigenvalue; PSS parameters optimization by the nonlinear programming approach.With nodal voltages expressed in the rectangular form, the present second order probabilistic load flow computation provides accurate voltage expectations, but not satisfactory voltage covariances, especially those covariances related to the real part of voltages. The correction of voltage covariances is considered in the computation of power expectations. But the linearized mode is used in the computation of voltage covariances. A better algorithm called as the complete model retaining the second order terms is presented in this thesis, and this approach is compared with several present methods at iterative equation and computational precision. Based on the PV and injection curves, the slack nodal curve is taken into account by using extended Joacbian matrix in the presented algorithm. In order to compare the computational errors of several models, the accurate expectations and covariances are calculated by repeated deterministic computation. Results show that the complete model retaining the second order terms is the most accurate model, and it can provide accurate voltage expectations and covariances.In the aspect of probabilistic eigenvalue analysis, the precisions of several probabilistic eigenvalue models are compared. The expectations and covariances of eigenvalues are computed by the linearized model, the simplified second order model,the second order model and the correction to system matrix A. All analysis are on two testing systems. Results obtained from the simplified second order can be acceptable, though there are still errors in the standard variances of eigenvalues. Results calculated from the second order modal should be more accurate in theory, but the results are not so much accurate and the computation requirement becomes much more. The computational precision of correcting to system matrix varies with the used testing system.In probabilistic PSS design, two probabilistic sensitivity indices are applied for PSS location and initial parameter value determination. The PSS parameters are coordinated by using the nonlinear programming technique. The objective function is composed of the expectations and variances of all the dissatisfactory eigenvalues. The approach is tested on an eight-machine system. Results show that the PSS parameter can be further coordinated by using the nonlinear programming technique.更多还原