A Methodology for Quantifying Flexibility in a fleet of Diverse DERs

TL;DR

This paper introduces a new metric and systematic methodology to quantify the flexibility of diverse distributed energy resources (DERs), validated through simulations and analysis of heterogeneity and control schemes.

Contribution

It proposes a novel metric based on ISO performance scores and a systematic procedure to quantify DER flexibility using simulation or optimization, accounting for heterogeneity and control parameters.

Findings

Flexibility from different DER fleets adds linearly.

The methodology is validated on centralized and PEM schemes.

Heterogeneity and control parameters influence flexibility quantification.

Abstract

This paper addresses the question: how many distributed energy resources (DERs) are needed to provide $\pm1$MW of flexibility over a number of hours? For this purpose, a metric based on an ISO's own performance score is proposed. Then, a systematic procedure is presented and validated that makes use of either a simulator or the solution to an optimization problem based on a nominal analytical formulation to get flexibility in terms of kW-per-device. Furthermore, simulation-based analysis indicates that flexibility from different DER fleets adds linearly, that is, the total flexibility provided by a mixture of different DER types can be obtained as a convex combination of their individual kW-per-device flexibility. The proposed methodology is validated on ($i$) a centralized coordinator and ($ii$) a device driven DER coordination scheme called packetized energy management (PEM). Furthermore, the effect of heterogeneity as well as PEM specific parameters such as packet length and mean time-to-request on flexibility is also quantified.