失稳模式变化的机理——五论暂态能量函数直接法

前文已证明，从多机积分空间到等值OMIB(单机无穷大系统)平面的PCOI( 部分惯性中心)映射保留了原多机系统首摆稳定性的充要条件。本文进一步剖析了多机因素 和复杂模型因素对映射OMIB系统各次摆动稳定性的影响，并将EEAC理论推广到多 摆稳定性。本文还澄清了失稳模式和临界模式这两个不同的概念，探讨了失稳模式随故障的 切除时间变化的机理；指出非理想的二群首摆失稳模式可能随故障切除时间而变，并可能存 在更临界的多摆失稳模式。最后，揭示了由笔者发现的ISD(孤立稳定区)及NARI (由ISD引起的邻域吸引子)现象的物理本质，从理论上证实当前普遍采用的逐步积分 法有可能搜索到错误的CCT(故障临界切除时间)，而沿用至今的CCT定义也是值得商 榷的。在EEAC理论指导下，由电力部电力自动化研究院开发的IEEAC(集成化EE AC)软件包有效地解决了上述连常规数值积分法也难以发现的问题。

THE MECHANISMS OF INSTABILITY MODES

A previous peper shows that in order to assess transient stability of a multimachine system, we can mapping its angle trajectories onto OMIB planes with the PCOI transformation and then examine the sta-bility of resulting time-varying OMIB systems,The present paper further dissects the influences of nonidealtwo-group dynamics and/or detailed models on the timevarying OMIBs , and augments the extended equalarea criterion(EEAC ) theory to multi-swing instability, The intrinsic link between instability modes andfault clearing time is uncovered. The revelation uf the ISD(solated stability domain ) and NARI(neighbor-hood attractor resulting from ISD ) phenomena gives a challenge to the regular practice on searching CCTwith numerical integration , and puts the widely accepted definition of CCt into question.