Modelling prosumer flexibility

This chapter details about the concept of flexibility and how prosumer can get involved with Local Flexibility Markets (LEMs) by quantifying and pricing their device flexibility using OpenTUMFlex. Following are the important terminologies used with understanding the concept of prosumer flexibility.

Background

The increasing share of renewable energy requires alternative methods to provide power system ancillary services to ensure a stable operation of the electricity grids. Recent research has inclined their interests towards the aggregation of small-scale system flexibility potentials to accommodate grid variations. The advancements towards local flexibility markets allow prosumers participation in solving grid congestion problems. In order to allow prosumers to interact with the LFMs and submit their bids, a flexibility model is required.

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Design

This research proposes an open-source flexibility estimation model that quantifies all possible flexibilities from the available prosumer devices and prices them. The ideology is utilize an energy management system (EMS) which usually evaluate optimal operation plan such load scheduling and add additional feature to it to compute device flexibilies. This allows the EMS to interact with energy markets for its day to day operation and as well allows prosumer to offer flexibility services to the LFMs.

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Flexibility

Flexibility is computed as a measure of quantifying the amount of deviation from the optimal operation of a device. For example, the following figure shows an abstract representation of a device flexibility. Considering the red line to be the optimal operation of a device then the blue region defines the possible deviation the device can undergo during any specific time without deviating from its device properties.

For example, lets suppose a PV system is generating 3kW of power between 12:00 and 12:15 in an optimal operating condition, then the maximum negative flexibility of PV system -3kW by curtailing the feed-in power.

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Terminologies

Prosumer
An electricity customer who can actively influence their generation or demand pattern
Flexibility
Flexibility comprises of the measures that influence the generation and/or consumption of the electricity in response to an external signal (price signal).
Positive flexibility
Flexibility measures that results in net addition of power to the grid.
Negative flexibility
Flexibility measures that results in net removal of power from the grid or curtailment of scheduled grid feed-in.
Local Energy Markets
Local energy markets are local exchanges that try to balance generation and demand close to real time.

Abbreviations

BSS

Battery Storage System

CHP

Combined Heat and Power system

DSO

Distribution System Operator

EV

Electric Vehicle

HEMS

Home Energy Management Systems

HP

Heatpump

HS

Heat Storage

LEM

Local Energy Market

LFM

Local Flexibility Market

MILP

Mixed Integer Linear Programming

PV

Phovoltaic system