Using the Transmission Congestion Expectation (TCE) in optimal transmission expansion planning

Abstract

Several performance metrics for power transmission systems are available, each with their own unique applications. The Loss of Load Expectation (LOLE) is one such metric. But despite its popularity, it is also known that it is complicated to compute when considering transmission line outages, limiting its general applicability in transmission system related operations like planning and market regulation. In this paper, we introduce the concept of Transmission Congestion Expectation (TCE) as a performance metric that estimates the expected number of hours in a year that a power transmission system experiences line overloading due to the unexpected outage of transmission lines. It is similar to the LOLE but requires significantly lesser data and computational resource. We present the steps in calculating this metric and for illustration purposes, we then demonstrate how this metric can be used in transmission expansion planning. We hope that this simple approach will help empower countries lacking technical expertise in this area and inspire future work on other possible applications of the TCE.