DEVELOPMENT OF AN ENERGY FUNCTION REFLECTING THE TRANSFER-CONDUCTANCES FOR DIRECT STABILITY ANALYSIS IN POWER-SYSTEMS

Direct stability analysis using an energy function has recently been w idely used for angular and voltage stability analysis in electric powe r systems. Considerable efforts have concentrated on seeking energy fu nctions for lossy power systems, accomplished only for the simple two- bus system. A new approach is presented to derive an energy function b y using the complex integral of bus current equations with respect to bus voltages. Under an assumption that all transmission lines have a u niform R/X ratio, it is shown that the energy function can be develope d for multimachine power systems with losses. The proposed energy func tion is tested on sample systems by comparing the time simulation meth od, which shows the validity of the proposed method.