基于小干扰分析的电压稳定机理研究

发布时间：2019-01-05 04:41

【摘要】：我国电网构架正向着大规模、远距离、超高压的形势发展,电力系统的运行状况越来越接近其极限状态,同时许多地区存在着高低压电磁环网以及用电负荷猛增的情况,这些都对保证电力系统安全稳定运行提出了更高的要求。上个世纪七十年代后陆续发生的电压崩溃事故给国民经济造成巨大损失,学术界在电压稳定方面的研究逐渐增多,并且也取得了一些成果,但是和功角稳定的研究程度相比还是缺乏对其本质理解的全面认识,在电压失稳的机理分析、研究模型及方法等方面仍需要进行不断研究。由于电压稳定机理研究缺乏统一的数学模型和数学分析方法,因此电压稳定机理研究理论不够成熟。本文在此基础上提出并建立包括发、输、用三个环节,突出电磁能量变化的电枢反应,计及影响电压稳定的各个因素的综合统一的动态、静态综合模型;并且借鉴成熟的功角稳定分析方法同时类比于其他稳定性分析数学方法而选择的小干扰分析法来分析电压稳定。目前大多数学者研究电压稳定认为电力系统动态行为表示为,而本文研究中强调动态方程为,多加了一组辅助方程,正是由于这组辅助方程才能准确突显电压失稳动态过程,完整描述电力系统动态行为中机械能与电磁能量的变化。前者的微分代数方程往往不能表现出电枢反应电磁能量变化时,同步机暂态电势Eq'衰减振荡是机端电压持续下降的核心因素。在电压失稳机理研究中本文认可例如负荷特性、电气距离、输电网络输送功率限制,OLTC动态特性等因素会影响电压稳定,但是本文更侧重于在系统受到小干扰时,同步机无功电流突然增大,由于同步机本身的固有特性,即使在不考虑励磁调节的机端情况下,也会出现暂态电势下降,从而加剧机端电压(网络节点电压)持续下降严重时出现电压崩溃。最终对电压稳定从物理角度及现象上做出定义,电力系统功角稳定性是同步而言的机械能存储于释放的现象;而电力系统电压稳定性是同步机中相对同步而言的电磁能量不突变而引起的自由分量衰减对电势的影响和去磁磁场的变化及输电网络的电压降。同时也为提高电压稳定性措施提供理论指导。
[Abstract]:With the development of large scale, long distance and high voltage power system in our country, the operation condition of power system is more and more close to its limit state. At the same time, there exists the situation of high and low voltage electromagnetic loop network and the surge of power load in many areas. All these put forward higher requirements to ensure the safe and stable operation of power system. Since the 1970s, the voltage collapse accidents have caused huge losses to the national economy. The research on voltage stability in academic circles has gradually increased, and some achievements have also been made. However, compared with the research degree of power angle stability, there is still a lack of comprehensive understanding of its essence, and the mechanism analysis, research model and method of voltage instability still need to be studied continuously. Due to the lack of unified mathematical model and mathematical analysis method in the study of voltage stability mechanism, the theory of voltage stability mechanism research is not mature enough. In this paper, a dynamic and static comprehensive model of armature reaction, which includes three links, namely, generation, transmission and use, is proposed and established, which highlights the variation of electromagnetic energy, and takes into account the various factors affecting voltage stability. The voltage stability is analyzed by using the mature power angle stability analysis method and comparing with other mathematical methods of stability analysis. At present, most scholars think that the dynamic behavior of power system is expressed as voltage stability, but the dynamic equation is emphasized in this paper, which adds a set of auxiliary equations. It is precisely because of this set of auxiliary equations that the dynamic process of voltage instability can be accurately highlighted. The variation of mechanical energy and electromagnetic energy in the dynamic behavior of power system is described. When the differential algebraic equation of the former can not show the variation of the electromagnetic energy of armature reaction, the Eq' attenuation and oscillation of the transient potential of the synchronous machine is the core factor for the continuous decrease of the terminal voltage. In the study of voltage instability mechanism, it is recognized that factors such as load characteristics, electrical distance, transmission power limitation of transmission network and OLTC dynamic characteristics will affect voltage stability, but this paper focuses on the small disturbance of the system. The reactive current of the synchronous machine increases suddenly, because of the inherent characteristics of the synchronous machine itself, even if the excitation regulation is not considered, the transient electromotive force will decrease. This results in a voltage collapse when the terminal voltage (network node voltage) continues to decline severely. Finally, the voltage stability is defined from the physical point of view and the phenomenon. The power angle stability of power system is the phenomenon that the mechanical energy is stored in the release in synchronization. The voltage stability of power system is the effect of the attenuation of free component on the potential, the change of demagnetizing magnetic field and the voltage drop of transmission network caused by the non-abrupt change of electromagnetic energy in synchronous machine. At the same time, it also provides theoretical guidance for improving voltage stability measures.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM712

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