【作者】 韩俊秀；

【导师】 宋建成；

【作者基本信息】 太原理工大学 ， 高电压与绝缘技术， 2012， 硕士

【摘要】 随着科学技术的日益进步,电力系统稳定运行逐渐成为关系国民经济健康发展和人们正常生活重要的前提,为满足人们对电能不断增长的需求,电力系统本身发生了很多相应的变化,对电力系统的各种合理性研究就越来越重要。电力负荷是电力系统稳定运行中较为重要的一部分,综合负荷建模又是电力系统分析研究的重要课题,合理的负荷模型的建立逐渐成为系统仿真和计算结果可信度和准确度的关键,但是由于负荷模型复杂多变的特点,对其建模相当复杂,因此,在进行电网电压稳定性的研究中负荷特性的研究和适用于电压稳定分析的负荷模型的建立是一项重要的工作。电力系统是由发电、输电、配电、用电等几个重要部分组成的具有强非线性的大规模的动力系统,描述系统的数学模型也是具有强非线性的微分代数方程组,系统中的物理量的变化速率也有很大差异。为了减少这种强非线性以及速率的差异性带来的计算和分析的难度,在研究过程中需要舍弃一些次要因素来降低所分析系统模型的阶数。随着电网规模的扩大,电压敏感负荷的增多以及负荷水平的加重,电压不稳定事故成为一个威胁电网安全并且亟待解决的问题,有必要研究负荷模型对电压稳定的影响。本文首先介绍负荷模型研究的必要性,分析讨论比较两种建模方法,基于本课题的需求及研究背景条件,确定较为适合也较容易实现的方法。概括介绍电压稳定性研究对负荷模型的要求,以及负荷模型的确定对电力系统仿真的不同影响,列出常见的几种静态和动态负荷数学模型,引出静态特征系数以及本课题将采用的动态负荷模型。在讨论稳定问题时,通常会采用静态负荷模型作为考虑对象,这对研究电力系统动态特性存在较大制约,需要综合考虑静态负荷和动态负荷。感应电动机负荷是动态负荷的主要成分,运用集结法将静态负荷和感应电动机负荷等值为一个综合结构的负荷。分析比较几种降阶方法,重点介绍摄动法理论、研究现状及其相关研究方法,详细介绍多重时间尺度法的数学依据,对感应电动机负荷的五阶模型以及摄动降阶的三阶模型进行详细的推导。介绍小干扰稳定的定义及研究方法,分析比较几种常见的静态和动态分析方法。针对感应电动机静特性对小干扰稳定临界电压的数学模型进行推导,采用小干扰特征值分析法研究三种模型的特征值随参数变化而变化的情况。一系列分析后得到的综合模型使后续研究分析过程变到简化,得到适用于课题研究的数据。对摄动法的运用避免了降阶的盲目性和不合理性,基于实际算例仿真进行比较分析,验证了摄动降阶模型的合理性和时效性,为判断元件快慢属性找到了一条较为合理的途径,为日后研究更为复杂的系统模型奠定了基础。通过分析模型参数对小干扰稳定临界电压的影响,为进一步研究负荷动态建模及其对小干扰电压失稳的预防及校正提供了有利依据,并验证摄动法引用的合理性。更多还原

【Abstract】 Stable operation of the power system is an important prerequisite for the healthy development of national economy and people’s normal life. With the increasing advances in science and technology, to meet people’s growing demand for power, the power system itself has undergone many changes, and all kinds of rationality of power system is becoming increasingly important.Power load is a more active part of the stable operation of the power system. The composite load modeling is an important issue for power system analysis, and reasonable load model is becoming the key of the credibility and accuracy of system simulation results. But load modeling is quit difficult for its characteristics of complexity and variability. Power system is a strongly nonlinear large-scale power system which consists of several important parts such as the generation, transmission, distribution, electricity, etc. The mathematical models of the system are also the strongly nonlinear differential algebraic equations, and the change rates of its physical quantities are quit different too. In order to reduce the difficulties of calculation and analysis brought by strongly nonlinear and rate differences, it is need to give up some minor factors to reduce the order of system model within the study, and the perturbation method avoid the blindness and irrationality of reduced-order. With the expansion of the grid-scale, the addition of the sensitive loads, the acceleration of the load growth and the aggravation of the load level, voltage instability incident is becoming a threat that must to be solved to the security of power system. In the first, this thesis introduces the necessity of the load model, discusses and compares two modeling methods, determines a more appropriate and more easily achieved method based on the research background conditions and the needs of this subject. Then it introduces the requirements of voltage stability to load models and the impacts of the load model on power system simulation, lists several common static and dynamic load mathematical models, and leads to the static characteristic coefficients and the dynamic load model which is adopted by this subject. While discussing the problem of voltage stability, the static load model has a big constraint for the study of power system dynamic characteristics. It is needed to both consider the static load and dynamic load, and the main component of dynamic load is induction motor load. At last, we value the static load and the induction motor load to a load with integrated structure by aggregation. This thesis analyzes several reduced-order approaches, and focuses on perturbation theory, its research status, and its associated research methods. Then it describes the mathematical basis of the multiple time scale method, and the original model and the reduced-order model based on the perturbation of induction motor load in detail is derived. This thesis presents the definition, research methods of voltage stability, analyzes and compares several static and dynamic analytical methods, and derives a mathematical model of the threshold voltage of the small signal stability in connection with the static characteristics of the induction motor. It elaborates the indicators of small disturbance voltage stability analysis and their response characteristics based on three models and the eigenvalue analysis method.The comprehensive model that through a series of analyzes simplifies the subsequent analysis process, and receives the data for this research. After the simulation, compare and analyze three models based on the actual examples, and verify the reasonable and timeliness of the perturbation model. All of these help to find a more suitable way to determine the component speed attribute, and would lay foundation for the more complex system model in future studies. The impact of the induction motor parameter changes to the small disturbance stability is given by using the practical examples. It is a useful reference for the further study of dynamic load modeling and prevention and correction to the system signal instability. And these verify the reference of the perturbation method is reasonable.更多还原