Diagnosis-Driven Co-planning of Network Reinforcement and BESS for Distribution Grid with High Penetration of Electric Vehicles

Abstract: While the rapid proliferation of electric vehicles (EVs) accelerates net-zero goals, uncoordinated charging activities impose severe operational challenges on distribution grids, including exacerbated peak loads, thermal overloading, and voltage violations. To overcome the computational intractability of jointly optimizing grid infrastructure reinforcements and battery energy storage system (BESS) installations, this paper proposes a novel three-stage diagnosis-driven co-planning (DDCP) framework. The methodology integrates a violation detection and quantification (VDQ) model to systematically identify system breaches, and a violation-mitigated BESS planning (VMBP) model for optimal BESS sitting and sizing. Specifically, Stage I of the DDCP framework diagnoses critical bottleneck lines that render standalone BESS solutions infeasible. Stage II targets cable upgrades exclusively at the Top-N prioritized bottleneck lines and Stage III then executes the optimal BESS deployment using a network-enhanced VMBP model. Furthermore, this study quantifies the EV hosting capacity thresholds before and after BESS integration across varying EV adoption rates and base voltages. Finally, a comprehensive comparative analysis evaluates four mitigation approaches: the VDQ-driven cable upgrade (VCU) model, the VMBP model, system-wide voltage uprating, and the proposed DDCP framework. The results demonstrate that the DDCP framework not only resolves the complex joint-optimization hurdle but also achieves the high techno-economic superiority in addressing high-EV-penetration challenges.