Improving hydrogeneration representation in a production cost model used for long-term transmission studies in the Western Interconnection

The Western Electricity Coordinating Council, recognizing the importance of interconnection-wide transmission planning, formed the Transmission Expansion Planning Policy Committee (TEPPC) in 2006. TEPPC is tasked with conducting regional transmission expansion planning studies involving system modeling; as well as performing analyses of future transmission congestion and operational impacts. TEPPC utilizes the production cost model (PCM) PROMOD IV© to model the Western Interconnection for these studies. In certain geographic regions, a high level of hydropower penetration necessitates careful consideration of hydrogeneration models used in the PCM to produce the most accurate system results. This work details the hydro modeling methods utilized by TEPPC for improving hourly hydrogeneration time series representations in transmission planning studies. The justification and benefits for using these methods are outlined in this paper, and the results of a 2019 transmission study are shown to illustrate of the advantages for employing these methods.