BC Hydro's Transmission Reliability Margin Assessment in Total Transfer Capability Calculations

Abstract

NERC requires considering the uncertainties in assessing the total transmission capability (TTC) by calculating a term called transmission reliability margin (TRM). As part of a new BC Hydro TTC calculator, an improved 2m +1 point estimation based method (PEM) was developed to estimate the standard deviation of TTC due to the uncertainties of system parameters including forecasted system load, generation patterns, inter-tie schedules and change in projected load and dispatch conditions as a result of system stress. The standard deviation of TTC is used to determine TRM. The developed method has now been accepted as part of new BC Hydro's TTC calculator for determining TRM in real-time and pre-scheduling timeframes. Typical results on BC Hydro's large scale system, which were obtained using the developed TRM method, are presented in this paper. The presented TRM method has already been filed as an attachment to a BC Hydro's report to NERC for meeting the mandatory reliability compliance.