Minimizing Bid Adjustments and Maximizing Flexibility: A Comprehensive Framework for Grid Prequalification of DERs

Distributed Energy Resources (DERs) offer great potential to provide flexibility-based services but come with operational challenges when integrated in the centralized ancillary service (AS) market operated by transmission system operator (TSO). The current market arrangement lacks sufficient resolution of distribution constraints during market clearing. To address this issue, a detailed grid prequalification process is required before DER participation in the centralized market. In this context, this paper introduces a detailed framework for distribution system operators (DSOs) to qualify DERs and adjust their operational limits, maximizing flexibility with minimal bid deviation. The framework employs network capability regions to consider distribution constraints, uses the Euclidean distance to reduce complex power deviations, and considers grid integration costs as a preference criterion for bid modifications. Results confirm that using a single network capability region allows for dynamic prequalification, which enhances transparency and reduces the need for bid adjustments. Additionally, considering grid integration costs can lead to savings on future reinforcement expenses for DSOs. The approach has been tested using IEEE standard bus systems, demonstrating enhanced flexibility in DERs, which is transferred to the TSO. This approach is suitable for larger systems having multiple DERs connected under a single DSO.