A Method for Selecting the Lines to be opened to Minimize the Imbalance between Total Generator Output and Total Loads in a Separated Power System

Abstract

A severe fault may cause a loss of synchronism between two groups of generators. And this may lead to a separation of power system network. If the imbalance between total power output of the generators in a group and the total load in the separated network is large, the deviation of frequency will increase or decrease and a further loss of synchronism will occur and result in a wide-area blackout To prevent a loss of synchronism from expanding, we propose a new method for selecting a set of power lines to be opened. The method comprises three steps. The first step is to collect lines that predict or detect out-of-step. The second step is to find the separated networks. The third step is to switch lines so that the imbalance is minimized. In the second step, a fast method of computing an inverse admittance matrix is developed and a new approach is developed to find the group of nodes that are connected and the group of nodes that are not connected. In the third step, a procedure to select lines that will be opened is developed in order to minimize the imbalance between total generator output and total load. The validity of this method is shown by simulations using several models including a East10-model and a large-scale model composed of 799 nodes.