Asymmetrically Reciprocal Effects and Congestion Management in TSO-DSO Coordination Through Feasibility Regularizer

Abstract

TSO-DSO coordination together with flexibility service pave the way for the grids to make the most of distributed energy resources while maintaining system secure operations. In T-D coordination, stemming from the diversity of distribution systems including sizes and renewable levels, vulnerable distribution systems may be placed in unfavorable working conditions under the same coordination with TSO. Also, the variance of coupling points affects transmission and distribution systems differently. This work proposes to formalize such heterogeneous effects, called “asymmetric reciprocal effects” (AREs), for the first time. AREs can be characterized through flexibility services and incorporated in T-D coordination to limit improper couplings that push the weaker DSO to its feasibility boundaries associated with long-term voltage stability and operational constraints including voltage and thermal thresholds. An advanced flexibility region construction technique is developed by leveraging the latest feasibility certificate using Kantorovich fixed-point theorem. AREs are then quantified using feasibility regularizers measuring the variations of feasibility regions of TSO and DSO due to coupling point fluctuation. A scalable approach based on statistics is also developed for AREs metrics. Simulation results of one-shot and 24 h optimal dispatch on single-TSO-multi-DSO model are presented to illustrate the concept and how AREs contribute to TSO-DSO coordination.