In the face of a substantial and uncertain growth of behind-the-meter Distributed Energy Resources (DERs), utilities and regulators are currently in the search for new network planning strategies for facilitating an efficient Transmission & Distribution (T&D) coordination. In this context, here we propose a novel distribution system planning methodology to facilitate coordinated planning exercises with transmission system planners through the management of long-term DER growth uncertainty and its impact on the substation netload. The proposed approach is based on the design of a transmission-aware distribution planning model embedding DER growth uncertainty, which is used to determine a "menu" of secure distribution network upgrade options with different associated costs and peak netload guarantees observed from the transmission-side, referred here as Netload Range Cost Curves (NRCCs). NRCCs can provide a practical approach for coordinating T&D planning exercises, as these curves can be integrated into existing transmission planning workflows, and specify a direct incentive for distribution planners to evaluate peak netload reduction alternatives in their planning process. We perform computational experiments based on a realistic distribution network that demonstrate the benefits and applicability of our proposed planning approach.
