RST Reloaded - Flexibilisation of the urban power supply system by adapting the existing ripple control system

"RST reloaded" utilises existing ripple control technology (RST) to activate flexible loads in a targeted manner to benefit the grid and thus create capacities for more renewable energy in urban electricity grids. The aim is to analyse technical potential and user acceptance in equal measure and validate them in an implementation. The approach is scalable, legally compliant and transferable to other municipal utilities.

Short Description

Starting point / motivation

Urban distribution system operators, such as Stadtwerke Mürzzuschlag, play a central role in the energy transition and in creating resilient cities. Their supply task and proximity to the city and people make them a key player in overcoming the challenges of the energy transition. As grid operators, they are confronted with the general challenges in the electricity grid. In addition to issues such as voltage maintenance and power limits due to the expansion of decentralised renewable energies, municipal grid operators have to comply with limits when feeding into the higher-level grids.

Stadtwerke Mürzzuschlag is allowed to feed a maximum of 6 MW back into the grid of Energienetze Steiermark, with feed-back values of 4 MW already being achieved on sunny days with low loads. The feed-back power limit also sets a limit for the further expansion of renewables. If the limit is reached, systems will either have to be curtailed or flexible loads will have to be used in future, which will have to be controlled in a way that serves the grid - a challenge as the digitalisation of the distribution grids is still inadequate

This could be remedied by using the ripple control system, which already switches loads that can be used flexibly in terms of time (boilers, night storage heaters, etc.) together in switching groups. These flexible loads are often connected to so-called 'low-tariff meters', which according to the SNE-VO in Styria may only be supplied between 22:00 and 06:00. There is therefore potential to utilise an existing technology to switch on many loads at times when there is a risk of the feed-in limit being exceeded.

However, the legal situation does not currently allow this, at least in Styria. In addition, the reaction of grid customers must be taken into account, as they generally react very sensitively to changes in the loads controlled via the ripple control system.

Contents and goals

The aim of 'RST Reloaded' is to make the available electrical flexibility in urban energy supply systems available by controlling them using a ripple control system, thereby creating capacities for the expansion of renewable generation capacities. The trial will take place as part of a regulatory sandbox in accordance with ElWOG §58a. The regulatory sandbox is necessary in order to be able to supply low-tariff meters outside the specified supply times.

Methods

The project will develop a suitable deployment strategy for the flexibilities activated by the ripple control (boilers, night storage heaters, etc.), which in turn should enable the installation of a further 1,500 kW of renewable capacity. In addition, 100 test subjects will take part in a social science study on reactions to the change in the system and the willingness to contribute to grid relief without financial compensation. Customers will be involved via a communication and feedback platform developed in the project. The basic scheme is shown in Figure 1.

Flowchart: Clarify basics (law, technology, data), develop strategy, sandbox application (approval required), implement system (communication, data, ripple control), test phase (check technology, involve users) — Figure 1: Schematic representation of the methodological approach in the project (Source: Project RST Reloaded)

Expected results

The innovative nature of the project is demonstrated by the fact that existing infrastructure is being used to increase the flexibility and resilience of the municipal electricity supply system. This is an approach that can be easily transferred to other municipal utilities and reflects the current state of digitalisation in distribution grids.

Another innovation factor is the consideration of user reactions through a qualitative and quantitative mix of social science methods as well as the consideration of future developments in energy law - keyword flexibility markets.

Finally, the development of options for communicating flexibility calls between grid operators and energy suppliers via the electricity market processes in Austria also contributes to innovation. This should minimise the risk of balancing energy costs due to unforeseen load behaviour.

Project Partners

Project management

4ward Energy Research GmbH

Project or cooperation partners

Energy Services Handels- und Dienstleistungs G.m.b.H.
Forschung Burgenland GmbH
Niederhuber & Partner Rechtsanwälte GmbH
SMARTSQUARE GmbH
Stadtwerke Mürzzuschlag GmbH

Contact Address

4ward Energy Research GmbH
Thomas Nacht
Reininghausstraße 13a
A-8020 Graz
Tel.: +43 (664) 88 500 336
E-mail: Thomas.nacht@4wardenergy.at
Web: www.4wardenergy.at