Increase transmission system utilization in systems with variable generation through risk based assessment

The continuously increasing penetration levels of variable generation in power system poses difficulty for operators to predict network operating conditions. As the uncertainty in these conditions increases, so does the need to consider larger security margins when reliability transfer limits are defined. Total Transfer Capability (TTC) defines to which extent the existing transmission assets can be utilized in a reliable manner. Thus, using highly conservative margin leads to an inefficient use of the transmission network. Therefore it is very important for operators to have an adequate methodology and tool to calculate system operating limits that allow higher utilization of the transmission network while maintain the required reliability level. The purpose of the work presented in this paper is two-fold. Firstly, to examine current industry practices to evaluate TTC under variable generation such as wind; and secondly to outline a methodology to calculate TTC in power system with a large penetration of variable generation. Preliminary results with the proposed methodology are presented through a case study conducted on the IEEE two-area Reliability Test System (RTS).