CORONA MODELING IN POWER-SYSTEM OPERATION

A phenomenological transmission line corona model is proposed to accommodate the different aspects of power system operation. Another model is also proposed to represent the effect of leakage current on high voltage insulators, with and without local discharge formation on their surface, in severe environmental conditions. Both the corona and leakage current models are then used as elements of the transmission line discretized model. This paper presents a more accurate solution at voltage buses by considering the corona effects as a variable shunt admittance depending on the updated voltage values which are calculated from each iteration in the load flow technique. A technique is proposed for reactive power optimization to find the control variables of switchable VAR sources which satisfy the operating system constraints and minimize a suggested objective function. The objective function is intended to minimize the costs of both the consumed switchable VAR sources and the active power losses in the tranmission line, taking into consideration the corona and leakage current effects. The minimization of the consumed VAR sources aims to reduce the overvoltage which increases the corona loss in power systems. A trade-off between the danger of corona existence and the advantages of overvoltage on the power factors is presented using the suggested performance indices of the bus voltages and power factors in the system. The feasibility of the proposed models and techniques is tested by applying them to the IEEE 14-bus test system.