A Robust Multiobjective Strategy for Short-Term Distribution System Upgrading to Increase the Distributed Generation Hosting Capacity

This work proposes a strategy that estimates the maximum distributed generation (DG) capacity that can be connected to the electric distribution system (EDS), when EDS upgrading actions are implemented. The problem is viewed from the distribution system operator (DSO) perspective and is formulated as a multiobjective optimization model that maximizes the DG capacity and minimizes the upgrading cost. Upgrading options include allocation of voltage regulators (VRs) and conductor replacement, which are coordinated with the application of generation curtailment, DG reactive power support, and voltage control using VRs. The uncertainty and variability of demand and DG power production are accounted for resorting to a multi-period robust formulation. The problem solution generates a set of upgrading plans, from which the DSO can select the one that meets its economic expectation and provides the EDS with the necessary capacity to accommodate the expected new DG. A post-optimization analysis is proposed to evaluate the impact of EDS upgrading on the DSO profit. Simulations are performed on a 135-bus EDS, and results show that the proposed strategy reveals an upgrading plan that increases the DG capacity up to 64.39% with a gain in the DSO profit of 5.43%, compared to the case without EDS upgrading.