Perspectives on distribution network flexible and curtailable resource activation and needs assessment

TL;DR

This paper presents a framework for activating flexible and curtailable resources in distribution networks to address voltage and thermal issues, including a novel optimization approach and flexibility needs assessment methodology.

Contribution

It introduces a multi-objective SOC-relaxed RDOPF with Pareto tuning, a flexibility needs assessment method, and quantifies reactive power flexibility impacts.

Findings

Reactive flexibility reduces active power flexibility needs by 50%.

The proposed Pareto tuning improves SOC relaxation optimality.

Methodology aids DSO flexibility planning and market procurement.

Abstract

{A curtailable and flexible resource activation framework for solving distribution network (DN) voltage and thermal congestions is used to quantify three important aspects with respect to modelling low voltage networks.} This framework utilizes the network states in the absence of such flexible or curtailable resources as the input for calculating flexibility activation signal (FAS). The FAS has some similarities with optimal power flow duals {associated with power balance constraint}. FAS due to drooping design, {incentivize corrective flexibility activation} prior to any network limit violations. {The nonlinear resource dispatch optimal power flow (RDOPF) utilizes FAS for the activation of flexible and curtailable resources. Solving the OPF problem for a large system is computationally intensive, and second-order cone (SOC) relaxation is often applied in the literature.} {First,} we highlight the multi-objective nature of SOC relaxed RDOPF. A Pareto front tuning mechanism {is proposed for choosing loss penalty factor} while reducing the optimality gap of the SOC relaxed RDOPF. {Secondly, we} present a methodology for evaluating temporal and locational flexibility needs assessment of a DN, which DSO's can utilize for flexibility planning {in operational timescales and procurement in the flexibility market}. {Lastly, we} quantify the impact of reactive power flexibility for a DN with varying load power factors. {Numerical simulations indicate that the presence of reactive flexibility reduces the active power flexibility needs by 50\% for the test feeder with 0.8 aggregated load power factor.}