EEAC与直接法的机理比较 (四)回顾与瞻望

A CRITICAL COMPARISON OF VARIOUS METHODS FOR TRANSIENT STABILITY ASSESSMENT Part Four Status and Prospects

讨论了长期困惑电力系统学术界的暂态稳定性理论和算法 ;归纳出 1 0个要素 ,即受扰程度函数、壁垒点、观察点、参考点、积分路径与被积函数、定性判据、轨迹稳定裕度、临界轨迹与参数极限值、迭代求解与初始轨迹、搜索策略与收敛判据。由 4篇短文组成的系列文章按照上述各要素 ,讨论了针对平衡点稳定性的李雅普诺夫法、将平衡点稳定性理论应用于有界稳定性的暂态能量函数( TEF)法以及针对有界稳定性的扩展等面积准则 ( EEAC)等 3种稳定性理论在大扰动稳定性分析中的应用。作为最后一篇 ,综合比较了这些理论和方法 ,并归纳了李雅普诺夫法和暂态能量函数( TEF)法不适合电力系统暂态稳定性分析的本质原因。指出 :严格的李雅普诺夫法可以给出偏保守的近似结果 ;TEF法给出的近似结果则既可能保守也可能冒进 ;扩展等面积准则 ( EEAC)在受扰轨迹精度的含义上保证了结果的严格性。进一步完善了 EEAC的描述 ,为其严格的证明提出了更规范的思路 ,并瞻望了有关的发展。

Ten essentials for large-disturbance stability theory are abstracted. They are disturbed-measure functions, the barrier point, the observation point, the reference point for the function and the integrating path, qualitative criterion, trajectory stability margin, critical trajectory and stability limits, iteration and the initial trail, searching strategy and convergence criterion. In terms of each of the essentials, Lyapunov direct methods, transient energy function (TEF) methods and extended equal-area criterion (EEAC) are critically compared in this four-part paper. Lyapunov function methods provide uniquely conservative assessment, however, TEF methods cannot even guarantee the conservativeness. This reveals why Lyapunov function methods and TEF methods cannot be applied to transient stability analysis of power systems. With the same accuracy as the disturbed trajectory, EEAC rigorously provides the necessary and sufficient conditions for stability. New requirements on stability analysis, such as es timating the stability beyond the observation period, early terminating simulation, probabilistic stability evaluation, risk assessment and risk management are discussed. More rigorous formulation and proof for EEAC are also proposed. This project is supported by National Key Basic Research Special Fund of China (No. G1998020301) and National Natural Science Foundation of China (No. 59920037).