【作者】 仲悟之；

【导师】 汤涌；

【作者基本信息】 中国电力科学研究院 ， 电力系统及其自动化， 2010， 博士

【摘要】 本文进行了受端系统暂态电压稳定的机理探讨、数学模型的建立、分析方法、暂态电压稳定和暂态功角稳定关系等方面的研究。此外,还阐述了暂态电压崩溃过程的事故特征及暂态电压失稳形式,提出了暂态电压失稳的判据。无功功率不是电压失稳的根本原因。受端系统暂态电压稳定问题属于全局稳定性问题,应该从输电网络输电极限、负荷动态特性以及受端系统电压支撑三个方面进行机理解释。从数学上看电力系统只有稳定或不稳定,但从物理上看电力系统的电压稳定和功角稳定二者本质不同,区分暂态电压稳定和暂态功角稳定是必要的。负荷动态特性对系统暂态电压稳定有很大影响,但负荷并不是暂态电压不稳定的唯一作用者,不能将暂态电压稳定和负荷稳定完全等价。在暂态过程的时间框架下,暂态电压稳定模型和暂态功角稳定模型之间的区别不是很明显,可以认为计及负荷动态特性的暂态稳定模型也可以描述暂态电压稳定性问题。需要特别强调的是用于暂态功角稳定的负荷模型与用于暂态电压稳定的负荷模型应该是一致的,不能因为研究问题的不同而采用不同的负荷模型。用时域仿真法详细地研究了感应电动机的稳定性、暂态电压稳定性、暂态功角稳定性三者的关系,感应电动机是否失稳与暂态功角失稳和暂态电压失稳没有直接的对应关系,尤其是不能把感应电动机失稳和电压崩溃简单地对应起来。研究了将包含感应电动机的暂态能量函数法应用于电力系统暂态分析。建立了包含感应电动机模型的结构保留能量函数,介绍了势能边界面法,提出在能量函数法的思想下,暂态功角稳定和暂态电压稳定的关系可以通过不稳定平衡点模式来分析,并由不稳定平衡点模式的不同而区分出两者。系统可能的失稳模式受负荷模型、负荷位置、网络结构、运行方式等众多因素的影响。基于时域仿真法、能量函数法和奇异诱导分岔理论,提出了一种暂态电压稳定分析方法。电力系统暂态稳定域可视为由不稳定平衡点的稳定流形和奇异面所构成,在时域仿真过程中除了监视系统的代数方程的奇异性外,还要核查系统状态是否过势能峰值。如系统暂态轨迹与奇异面相交,则发生暂态电压失稳；如系统暂态轨迹与PEBS面相交,则可能发生暂态功角失稳也可能发生暂态电压失稳,此时需要从主导UEP模式的角度来进一步研究,由主导UEP模式的不同而区分出两者；如系统暂态轨迹不与这些面相交,则系统暂态稳定。提出了一种暂态稳定过程中动态戴维南等值参数跟踪方法,其基本思想是：跟踪计算系统暂态稳定过程中每一步的戴维南等值参数,然后根据每一步戴维南等值后的简单系统进行暂态电压稳定判断。课题组已基本解决了基于仿真的动态戴维南参数跟踪计算方法；基于测量的方法还需要进一步完善。在此基础之上给出了电压薄弱节点、电压枢纽节点、振荡中心节点的处理方法,研究了基于动态戴维南等值的暂态电压失稳判据,提出了应用于实际系统的算法流程,并进行了仿真验证。通过对实际电网的暂态电压稳定仿真计算,解析了暂态电压崩溃过程的事故特征,结合事故特征分析给出了三种暂态电压失稳的形式；从对实际电网的仿真计算出发,结合全文的研究成果,给出了暂态电压失稳的判据。更多还原

【Abstract】 This dissertation conducts research work on the mechanisms, mathematics modeling and analysis methods of voltage stability in receiving-end grid. The relationship of transient voltage stability and transient angle stability is discussed thoroughly. The accident characteristics of transient voltage collapse and modes of transient voltage instability are expatiated. The criterions of transient voltage instability are presented.The reactive power isn’t the ultimate reason of voltage instability. The transient voltage stability problem of receiving-end grid belongs to whole stability problem, which should be expounded from transmit electricity power ability limit of transmission lines, dynamic characteristics of load and insufficient reactive power supply in receiving-end grid. From mathematics point of view, the power system has stability and instability. But from physics point of view, voltage stability and rotor angle of powr system are different in essence. The division of transient voltage stability and transient rotor angle stability is essential. The dynamic characteristics of load have very great influence to transient voltage stability of power system, but load isn’t the only factor, transient voltage stability shouldn’t equal to load stability completely.In transient time frame, the mathematics modeling division between transient voltage stability and transient rotor angle stability isn’t very clear. The transient rotor angle stability modeling considering dynamic and static load characteristics already can describe transient voltage stability problem. It is very important that the load model used in transient angle rotor stability and used in transient voltage stability should be identical, it isn’t correct to adopt different load model because of different research problem. The relations of induction motor stability, transient voltage stability and transient rotor angle stability are studied detailedly by time domain simulation. The induction motor instability or not doesn’t have direct corresponding relation to transient voltage instability and transient rotor angle instability. Especially, the induction motor instability doesn’t equal to voltage collapse.The power system transient analysis is studied through adopting transient energy function method including induction motor. Structure preserving energy function including induction motor model is founded, and potential energy boundary surface (PEBS) mothed is introduced. Under the light of energy function method, transient rotor angle instability and transient voltage instability can be thought as different unstable mode, and be distinguished from each other by characteristic of unstable equilibrium point. The possible unstable mode is influenced by load model, load location, network structure and system operation mode etc.A transient voltage stability analysis method is put forward based on time domain simulation, energy function method and Singularity Induced Bifurcation (SIB) theory. The transient stable domain of power system is made up of stable manifold of unstable equilibrium point and singularity surface. In the time domain simulation process, the singularity of algebra equations and potential energy peak value should be watched. If transient track intersect with singularity surface, then transient voltage instability will be happen; if transient track intersect with PEBS surface, then transient voltage instability of transient rotor angle instability maybe happen, it should be studied from UEP mode; if transient track doesn’t intersect with these surfaces, then system is transient stability.A dynamic thevenin sequivalent parameters tracking method in transient stability is put forward. Its basic thinking is:thevenin sequivalent parameters is calculated in each step of transient stability process, then the transient stability is judged based on simple thevenin sequivalent system. The dynamic thevenin sequivalent parameters tracking calculation method based simulation is solved basicly, the method based on measure should be perfected. The voltage weakness node, voltage load-center node and oscillation center node are put forward. The transient voltage instability criterion based on dynamic thevenin sequivalent is studied. The arithmetic flow applying to actual system is put forward, and the simulation checkout is done.Through the transient voltage stability simulation analysis of actual power grid, the transient voltage collapse characteristics are resolved. Combining with accident characteristics analysis, three transient voltage instability modes are put forward. Faced with actual power grid, the criterions of transient voltage instability are brought forward combining the whole research.更多还原