Flexible and curtailable resource activation in three-phase unbalanced distribution networks

TL;DR

This paper introduces a network-state driven framework for activating flexible and curtailable resources in three-phase unbalanced distribution networks, effectively reducing voltage and thermal issues while considering network imbalances.

Contribution

It proposes a novel FAS design based on nodal sensitivities and optimal power flow duals, accounting for unbalance and incentivizing active/reactive power flexibility.

Findings

Reduces voltage unbalance factor by over 80%

Effectively mitigates network voltage and thermal issues

Quantifies flexibility needs by location and time

Abstract

The need for flexibility and curtailable resources is crucial for ensuring the healthy operation of future distribution networks (DN). In this work, we propose a network-state driven framework that distribution system operators (DSOs) can utilize for activating flexible and curtailable resources for alleviating network voltage and thermal issues, while accounting for network voltage and current imbalances. This approach assumes the availability of dynamic network state information and uses nodal sensitivities for calculating a flexibility activation signal (FAS). The signal design is motivated by volt-Var and volt-watt inverter control, and thus bounded. The FAS also considers network voltage and current imbalances and incentivizes activation of active and reactive power flexibilities for reducing imbalance in addition to mitigating voltage and thermal imbalances in a three-phase unbalanced distribution network. The FAS design resembles optimal power flow duals, often used as locational marginal prices. The gains associated with the imbalance component of the objective function of three-phase unbalanced resource activation (TPU-RA) is performed using Pareto optimality. A numerical case study is presented showing the efficacy of the proposed framework in avoiding network issues while reducing voltage unbalance factor by more than 80\%. Further, DN's flexibility needs are quantified for location and time of day.