【作者】 张剑云；

【导师】 孙元章；

【作者基本信息】 清华大学 ， 电气工程， 2006， 博士

【摘要】 大扰动是电力系统暂态稳定的主要威胁之一。为了观测、识别并控制大扰动,需要在广域测量系统与特别保护系统的基础之上构建广域保护体系。广域测量系统借助于相量测量装置来观测大扰动,而特别保护系统借助于紧急控制来控制大扰动。对于大型电力系统而言,通常可以在成百上千的地点安装上述观测与控制装置。所以需要为测量装置和紧急控制选择理想的位置,以有效观测和控制因大扰动而引起的系统暂态功角失稳。这就是本论文研究的主要问题:为大扰动的暂态安全防御配置广域观测和紧急控制的地点。本论文的主要目标是,建立大扰动观测和控制配置的理论基础,为电力系统提出完整而有效的配置方法,并将这套方法应用于一个具体的大型电力系统。本论文研究了严重受扰电力系统的动态特性,通过主导不稳定平衡点的性质来分析大扰动下系统失稳的特征。在该点展开模式分析,并引入模式能控性与能观性的概念,提出秩判据,为大扰动观测和控制的配置奠定理论基础。提出基于主导不稳定平衡点的配置方法。在结构保留模型中以输入和输出来表示紧急控制和测量信号,并对系统在主导不稳定平衡点进行线性化模式分析,最终获取模式能观性和能控性矩阵,以此来选择广域观测和紧急控制的地点。提出基于临界割集的配置方法。引入电压校正,在计算割集脆弱性指标时使用主导不稳定平衡点处的电压值,以准确获取临界割集。系统功角失稳主要引起临界割集支路的相角差或功率的增大,这既可以用测量装置来观测,又可以用紧急控制来抑制。在此基础上的功率灵敏度分析可以为选择紧急切机和切负荷的地点提供有价值的参考。建立大扰动分析的框架,将主导不稳定平衡点的不稳定模式、机组分群和临界割集三者结合起来,全面分析故障失稳模式。总结了为大扰动配置广域观测和控制的方法,并实际应用于南方电网。更多还原

【Abstract】 Large disturbances have always been one of the main threats to transient stability of power systems. Wide area measurement system (WAMS) and special protection system (SPS) are adopted to observe, detect, and control such disturbances, forming the architecture of wide area protection (WAP). Phasor measurement units (PMUs) can be installed in WAMS to obtain wide area measurements detecting large disturbances. And emergency controls can be armed in SPS to take corrective action against large disturbances.There are thousands of available locations for the installation of such observers and controllers, especially in a large-scale power system. Hence it is a natural and important issue to decide where are the ideal sites for measurements to observe the system separation arising from a large disturbance and where are the ideal sites for emergency controls to act against angular instability due to a large disturbance. The issue is termed the placement of wide area observers and controllers for system protection against large disturbances, which is the main focus of the study in this dissertation.The purpose of the dissertation is to lay the theoretical foundation for the placement of wide area observers and controllers for system protection against large disturbances, to present integrated and effective placement approach for power systems, and to apply the placement approach to a specific large-scale power system.The dynamic behavior of power systems after large disturbances is studied first of all. The trajectory of severely disturbed power systems will pass by controlling unstable equilibrium point (UEP) on the verge of losing stability, which is an inference of stability region theory. Then the characteristics of controlling UEP largely reflect system separation due to large disturbances, which can be revealed via modal analysis. The concepts of modal controllability and observability are introduced into the modal analysis at the controlling UEP of a large disturbance. Rank tests are proposed to qualify the placement to ensure the unstable modes of the disturbance controllable or observable. The rank tests are the general rules imposed on the placement of observers and controllers.A placement approach based on controlling UEP is presented. Structure preserving model of power system is expanded with input and output to accommodate emergency controls and measurements. The model is linearized with respect to controlling UEP and then reduced to the network-reduction model. Finally diagonal canonical form can be obtained, and the mode observability and controllability matrices are utilized to select the suitable locations of wide area measurements and emergency controls.Another placement approach based on critical cutset is also presented. Voltage correction is proposed to obtain critical cutset more exactly. Cutset vulnerable index is corrected using bus voltages at controlling UEP instead of at SEP, which can accommodate the characteristics of system trajectory following large disturbances. Power systems losing synchronism mainly suffer from the increase of line angle differences or line flows in critical cutsets, which can be captured by measurements and be withheld by emergency controls. Then the sensitivity of line flow of the critical cutset with respect to a generator or load power can indicate whether generation tripping or load shedding is effective at the site, which can be utilized to select the suitable locations of emergency controls.The architecture of large disturbance analysis is constructed to reveal the mode of disturbance, in which unstable modes of controlling UEP, grouping of generators, and critical cutset can be integrated. The procedure of the placement of wide area observers and controllers for system protection against large disturbances is summarized and applied to China Southern Power Grid.更多还原