This paper presents some preliminary results to reveal inherent characteristics of short-term voltage dynamics based on a relatively new conception called mixed monotone decomposition. An approximate linear dynamic system is established firstly by using Dommel-Sato iterative method and linearization techniques to differential algebraic equations. Then mixed monotone systems and mixed monotone decomposition conceptions are introduced. Furthermore, we use a three-machine test system to demonstrate the concept of mixed monotone, which are helpful to promote further qualitative analysis and improve control performance.

bilateral constraint,mixed monotone systems,order preserving flows,short-term voltage dynamics