Risk based TRM evaluation by probabilistic approach

In a new competitive environment, to efficiently manage the utilization of the transmission networks, the definition of available transfer capability (ATC) has been proposed. According to the North American Electric Reliability Council (NERC)´s definition, ATC depends on several parameters, i.e. total transfer capability (TTC), transmission reliability margin (TRM), and capacity benefit margin (CBM). This paper is focused on the calculation of TRM, which is one of the security margin reserved for any uncertainty of system conditions. The TRM calculation by the probabilistic method based on modeling of load forecast error and error in transmission line limitation is proposed in this paper. By consideration of the proposed risk analysis concept, the appropriate required amount of TRM can be obtained. The advantages of the proposed method are illustrated by an application to the IEEE 118-bus model system