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1、电压稳定性评估方法的研究摘 要电力系统是一个具有高度非线性的复杂系统，随着电力工业发展和商业化运营，电网规模不断扩大，对电力系统稳定性要求也越来越高。在现代大型电力系统中，电压不稳定/电压崩溃事故已成为电力系统丧失稳定性的一个重要方面。因此，对电压稳定性问题进行深入研究，仍然是电力系统工作者面临的一项重要任务。从国内外一些大的电力系统事故的分析来看，发生电压崩溃的一个主要原因就是无法预计负荷增长或事故发生后可能导致的电压失稳的程度和范围，难以拟定预防和校正的具体措施。因此普遍认为，负荷特性在影响电压稳定性的诸多因素中至关重要，它从很大程度上决定了电压失稳和电压崩溃的进程。所以，我们有必要在负荷
2、模型基础上考虑采用更好的方法来进行电压稳定性评估的研究。本文首先介绍了电压稳定性研究内容、研究方法及现状，阐述了当前电压稳定分析中常用负荷模型及综合负荷模型的特点。提出了一种将负荷导纳模型法和电力系统分析综合程序用户程序接口（PSASP/UPI）相结合，快速求取系统静态电压稳定极限及节点P-V 曲线的方法。该方法很好地解决了常规潮流计算在临界点收敛困难的问题，并大大提高了计算速度和精度。通过山西长治地区电网的实例太原理工大学硕士研究生学位论文II验证，可以有效应用于实际系统节点电压稳定状况的分析，且易于程序实现。电压稳定性评估主要涉及到预测、模式识别、分类和快速求解，这决定了它很适合于用人工神
3、经网络技术解决。本文详细介绍了神经网络模型的特点、算法原理及结构设计，采用电压稳定性接近 L 指标作为评估指标，用经典的 BP 网络建立了电压稳定性评估的静态和动态模型。静态评估模型基于潮流计算，训练结果很好地反应了在给定负荷增长方式下各节点功率和负荷节点电压的非线性映射关系；动态评估模型则基于综合负荷模型，计及了感应电动机的动态过程，采用两个 3 层 BP 网络分别对系统进行分类及预测。通过 WSCC-9 节点系统和 3 机 12 节点系统仿真，证明了该方法的有效性。通过电压稳定性评估的研究，我们可以找到更好地判定电力系统电压稳定性与否及稳定程度的方法，为实现在线、实时监测系统安全运行奠定基
4、础。关键词：电压稳定性评估，负荷模型，PSASP/UPI，P-V 曲线，人工神经网络，BP 网络，L 指标，感应电动机太原理工大学硕士研究生学位论文IIIRESEARCH OF ASSESSMENT METHOD ON VOLTAGE STABILITYABSTRACTPower system is characterized by the growing size and complex of enormous number of generating units, loads and transmission lines that included in the system. With
5、development of electric power industry and commercial operation, electric power system scale is extending, demands to reliability are higher and higher. Power system voltage instability or voltage collapse is an important factor in power system instability in large modern electric power system. Stud
6、ying voltage stability is still an important task that electric workers face. From the analysis on some large accidents of power system both at home and abroad， a main reason for voltage collapse is that people cannot estimate voltage instability extent and range, cannot study out relevant preventio
7、n and emendation measures after load increase and accident. Thereby, load characteristic is generally regarded as a very important influence factor on voltage stability, and it can largely determine the course of voltage stability 太原理工大学硕士研究生学位论文IVand voltage collapse. So, it is necessary to researc
8、h better methods of voltage stability assessment based on load models.At first, this paper introduces the contents, methods and their actuality of voltage stability research in power system，elaborates the characteristics of every load model and synthetic load model in current voltage stability analy
9、sis. A Fast method of getting the static voltage stability limit and P-V curve is presented combining load admittance model method with Power System Analysis Software Package/User Program Interface(PSASP/UPI). The problem of convergent difficulty of the load flow computation close to the limit is av
10、oided effectively, as well as the calculating speed and accuracy is improved obviously using the method. With the instance of Changzhi district power system, it is verified that the method can be used to analyze practical power system voltage stability and easy to be programmed.The voltage stability
11、 assessment mainly involves prediction, pattern recognition, classification and fast solution, which are well solved using ANN (artificial neural network) technology. This paper introduces ANN models characteristics, algorithm principle and framework design in detail, then establishes system static
12、and dynamic assessment models using classical BP network which make voltage stability proximity L indicator as assessment indicator. The training results of static assessment model which bases on load 太原理工大学硕士研究生学位论文Vflow calculation can reflect the nonlinear mapping relation between every bus power
13、 and load bus voltage on the condition of given load increasing mode; The dynamic assessment model, which is based on synthetic load model and takes account of the dynamic course of induction motor, uses two three-layer BP network to make classification and prediction respectively for system. With t
14、he instance of WSCC-9 bus and 3 generator-12 bus power system, it is verified that the method is effective to voltage stability assessment for power system.Through research on voltage stability assessment, we can find better methods to estimate whether voltage is stable and then to calculate stabili
15、ty range. It will establish basic for achieving online, real time monitoring system safety operation.KEY WORDS: Voltage stability assessment, Load model, PSASP/UPI, P-V curve, ANN, BP network, L-indicator, Induction motor 太原理工大学硕士研究生学位论文VI目 录第一章 绪 论 .11.1 课题研究的目的和意义 .11.2 电压稳定性及其类型 .21.2.1 电压稳定性定义 3 .21.2.2 电压稳定性和功角稳定性的关系 3 .31.2.3 电压稳定性的分类 6 .41.3 电压稳定的研究内容 7.41.4 电压稳定的研究方法和现状 21,22.61.4.1 静态分析方法 .
