A hybrid approach for planning and operating active distribution grids

TL;DR

This paper presents a hybrid planning and operation methodology for active distribution grids that integrates AC optimal power flow analysis with local control strategies to enhance grid security and mitigate voltage and congestion issues.

Contribution

It introduces a co-optimization approach that combines planning and operational phases using AC OPF results to generate local control curves for DERs without communication.

Findings

Successfully mitigates voltage violations and congestion

Performs comparably to centralized OPF solutions

Outperforms traditional local control schemes

Abstract

This paper investigates the planning and operational processes of modern distribution networks (DNs) hosting Distributed Energy Resources (DERs). While in the past the two aspects have been distinct, a methodology is proposed in this paper to co-optimize the two phases by considering the operational flexibility offered by DERs already in the planning phase. By employing AC Optimal Power Flow (OPF) to analyse the worst-case forecasts for the load and distributed generator (DG) injection, the optimal set-points for the DERs are determined such that the network's security is ensured. From these results, the optimized individual characteristic curves are then extracted for each DER which are used in the operational phase for the local control of the devices. The optimized controls use only local measurements to address system-wide issues and emulate the OPF solution without any communication. Finally, the proposed methodology is tested on the Cigre LV benchmark grid confirming that it is successful in mitigating with acceptable violations over- and under-voltage problems, as well as congestion issues. Its performance is compared against the OPF-based approach and currently employed local control schemes.