Fundamental Research on Transient Behavior of Power system and Criterion for Detecting Onset of Instability

1.电力系统各种稳定性的研究电力系统的动态行为可用高阶非线性微分方程组来描述。因此，电力系统中一些现象的发生机制是很难理解的，因为它们依赖于动力系统的全局结构。(A)暂态现象：针对保证电力系统行为稳定的吸引子池的全局结构，数值求出了控制吸引子池边界的不稳定极小集。(B)电力系统之间的摆动现象：对于系统间的同步、摆动现象和电力系统间的异步性，证明了初值空间的分类可能依赖于数值上的收敛。结果表明，吸引子盆地的结构与稳定性判据有重要关系。电力系统中基于电力电子设备的稳定性研究各种电力电子设备是用来控制电力系统的。然而，为了避免开关非线性，这些器件是不可避免的。得到了以下结果：(A)开关不稳定判据：自激电力电子电路表现出由负载和设置条件引起的开关不稳定。这项研究是为了从实验和数值上弄清楚这种不稳定性。修正的李雅普诺夫指数同样适用于这些电路。(B)连续-离散混合系统的稳定性：将混杂系统理论引入到含有开关元件的电力系统的分析中。

1. Studies on Various Stabilities of Power SystemThe dynamical behavior of power system is described by higher order nonlinear differential equations. Therefore it is difficult to realize the onset mechanism of several phenomena in power system because they are depending on the grobal structure of its dynamical system. The obtained results are as follows ;(a) Transient Phenomena : Relating to the grobal structure of attractor basin which insures the stabilization of power system behavior, the unstable minimal set which governs the boundary of the basin are numerically obtained. Then the attractor basins of eternal asynchronization which covers the basin of stable attractor are classified numerically.(b) Swing Phenomena Between Power System : As for the synchronization, the swing phenomena and the asynchronization between power systems, it is shown that the initial value space is possibly classified depending on the convergence numerically. The structure of the attractor basins is shown to have an important relation to the criterion of the stability.2. Studies on Stability Based on Power Electronics Apparatus in Power SystemVarious power electronics apparatuses are intended to control power systems. However, the apparatuses are inevitable to avoid the switching nonlinearity. The following results are obtained ;(a) Criterion of Switching Instability : Self excited power electronics circuits show the switching instability caused by the load and setup conditions. The research is performed to make the instability clear experimentally and numerically. The modified Lyapunov exponent can also be used in these circuits.(b) Stability in Continuous-Discrete Hybrid System : The theoretical studies are performed to introduce the Hybrid System Theory to the analysis of the power system with switching elements.