An Efficient Method of Network Simplification for Islanding Control Studies of Power Systems

System splitting is the last defense line protecting power systems from wide-area blackout. The latest achievement about the active splitting control is based on the scheme of "strategy searching and verifying", where all the lines in the power network are assumed to be allowed to trip off. Therefore splitting control, especially for a large-scale power system, is very complicated in general because a combinatorial explosion of strategy space happens. This paper studies a network preparation method that decreases the system scale to an acceptable level. By analyzing the physical connection and electric distance of nodes, load condition of lines and topological characteristics of original power networks, a simplified system is formed according to the proposed method, which is much smaller in scale than the original one but keeps most of the static and dynamic characteristics of the original system. Simulations on IEEE 68-bus system show that the proposed preparation method is necessary, feasible and effective, especially for larger- scale power systems. It not only saves the time spent on strategy searching and verifying efficiently, but also keeps as many feasible strategies as possible.