DSOs are experiencing a growing number of challenges in the grid due to fluctuations in private consumption as well as variable power injections from local intermittent Renewable Energy Sources (RES). In northern European grids such as in the Island of Fur (Denmark) consumption fluctuations are likely to be related to large electric residential and commercial heating systems (heat pumps), industrial loads and peaks due to electric cooking. On the other hand, production fluctuations are mostly related to sudden variations of injected power by installed PV and wind turbines.
While the current distribution grid configuration is sufficiently strong to bear the current status, growth in RES penetration, electric mobility and heating (stimulated because of the de-carbonization policies), may create problems in the longer term, thus resulting in significant needs for investments in strengthening the distribution grid. Moreover, even in case grid reinforcements needs would not became a reality, lack of time correlation between loads and generation patterns would anyways result in a reduced potential for self-consumption, and thus on lower decarbonisation effects. Therefore, the problem will just be shifted from the need to improve the local distribution grid to the need of investing more on interconnections at medium and high voltage level and on deployment of more instantaneous, controllable plants.
Installation of storage system at different levels in the grid is considered by the local DSO as a potentially interesting solution to help improving self-consumption, increase grid flexibility and deferring grid reinforcement efforts.
The Danish island of Fur is small island in the municipality of Skive, which host a small community of users which have been involved already in several Danish and EU R&D projects including the GreenCom project, coordinated by partners ISMB and participated by partners FIT and ENIIG.
In order to allow EU utilities such as ENIIG and their customers to pursue more informed investments in storage, while increasing RES self-consumption and avoiding heavy investments in strengthening the gird, S4G will study methodologies for planning, evaluating and controlling distributed storage installations at user premises and at substation level in a coordinated fashion. Figure below depicts the reference architecture of the “Storage Coordination” scenario and test site, covering a number of control and evaluation cases.
The scenario involves five residential Fur houses already provided with storage. Such houses feature various sizes of PV installations (ranging from 5 to 12 kW sizes) and are all connected to the same distribution radial. Such houses will be provided with an USM, integrated with the residential ESS and a dedicated local GUI. Similarly, a substation-level ESS will be deployed on-site. Overall, all available control capabilities will be interconnected with the DSO SCADA system, thus enabling cooperative behaviours in the storage systems.
These settings are quite representative of typical residential areas in the suburbs. For this reason this will represent a sensible test site to evaluate a number of control and planning cases where storage is needed as a buffer for fluctuations. S4G will provide DSOs with tools, control and planning methodologies to perform technical and economic comparative evaluations.
In order to cope with this challenging scenario, S4G will study methodologies for planning, evaluating in advance and controlling storage installations communicating and cooperating with storage systems by means of open, standardized interfaces. S4G will support the design and sizing of local storage system and their impact on the cost, manageability and environmental sustainability of the storage process, both from the private users and from the local DSO point of view. Such analysis will result in the definition and pre-design of control interfaces required to support optimal coordinated charging also taking into account user needs and grid signals from the AMI. This will allow deployed storage systems to implement an optimal control strategy for jointly controlling the charging process and the storage, to benefit the end-user and minimize impact on the grid. In the commercial case, the S4G DSF will help optimal sizing and design of large-scale storage to stabilize the grid and help the DSO. At this purpose, the S4G DSF will provide key information about the costs and benefits of such installations, as well as suggesting the best control strategy for such system once the storage enters the operational phase.
Overall, analysis, development and evaluation activities for this scenario will be deployed in the Fur test site and led by partner ENIIG.