Congestion-based Zonal-to-Nodal Disaggregation for Energy Storage Planning

To manage the complexity of long-term grid planning, capacity expansion models typically operate at a zonal level, aggregating generation, transmission, and storage capacity. On the other hand, validating and evaluating planning portfolios requires a nodal-level resolution, especially for energy storage, as its performance and value highly depend on local grid conditions. This paper presents a novel method for siting and sizing storage based on transmission capacity and congestion. In particular, each node’s storage need is assessed by summing the products of line utilization and capacity across its incident lines, capturing both congestion severity and transfer capability. This metric is then used to allocate zonal storage capacity to individual nodes based on their severity ranking. The proposed method is demonstrated on the nodal Western Interconnection power grid, highlighting its potential to inform more granular and effective storage planning strategies.