“Flexibility” and the importance of TSO – DSO information sharing

The electric power systems have been centralized and organized into generation, transmission and distribution, with customers at the end of the supply chain. Traditionally, the power grid has operated on a unidirectional design where electricity generated by large power plants is transported via transmission and distribution networks to be delivered to customers.

Over the recent decades, we have witnessed the emergence of distributed energy resources (DERs) such as rooftop solar photovoltaics (PV) installations, battery energy storage systems, plug-in electric vehicles, and smart home appliances that are becoming active participants in the electricity system.

The increasing penetration of distributed energy resources and the emergence of new market players – such as prosumers, aggregators and active consumers – will usher in a new era of grid management. To take advantage of these new opportunities and to keep pace with both the transformation of the power sector and changing customer needs, distribution system operators (DSO) will need to adjust their current role.

This change is a similar to the one transmission system operators (TSO) recently went through. They had to make a paradigm shift on their grid operations and planning process as decentralized resources such as renewables have impacted the transmission system.  We have seen various challenges for the TSOs as they integrate increased numbers of renewables into the electricity grid – the lack of inertia, the frequency behavior of the grid, and extreme voltage dips.  These are challenges for the TSOs because they are responsible for the grid system security. With the lack of inertia due to large fluctuations and the lack of voltage support, system security and stability will continue to be a challenge for TSOs.

“Coordination is one of the key challenges for the US power grid based on distributed and renewable generation. “

The coordination problem that evolves between electricity generators and the distribution grid operators continue to be key discussion areas and are at the forefront of every industry conference and research papers. The TSO can make use of flexibility via the balancing market to react to unpredicted deviations from the production or usage schedule. To do so, power plants and some aggregated distributed generators are leveraged. The further the energy transition proceeds, the lower the capacity of power plants that are connected to the transmission grid directly as the total installed capacity of conventional power plants decreases.  This shift is making it necessary that distributed generation participates in the balancing market. Some larger battery storages and virtual power plants are already participating in the balancing market, but still on a proof-of-concept basis.

For distributed generators to participate effectively, we need to secure that the DSO has access to information about these activities to apply this into the load projection models for the distribution grid. Currently, the DSO only knows that one of its grid users is active on the balancing market (via the pre-qualification process). It does not have detailed information what the grid user from its network is offering, nor does it know the TSOs demand at this specific point in time. At the same time, the TSO has no information about the current status of the distribution grid at the time of the flexibility request.  Looking at possible issues or scenarios, it could happen that the TSO requests flexibility from a distributed generator that puts the distribution grid’s stability at risk. This is not the intention of the TSO, but due to physics, this could be the outcome. The more generators or consumers from the distribution grid become active, the stronger the potential impact on the grid stability on the distribution grid.

“For TSO & DSOs to securely share data, standards for data management and data sharing need to evolve.“

Data management arrangements should serve to protect the privacy of personal data, and customers should be able to determine how their data is used.  DSOs will need to develop innovative systems to solve network constraint issues and to manage the injection of variable power. 

To support this flexibility, a critical operational data platform is needed to enable real-time data gathering at DER locations and long-term storing for this data for modeling.  The use of this data to support complex grid modeling both for distribution and transmission operations and grid planning will be key to grid flexibility and this transition. 

Today, more data comes from more assets distributed across more sites, and more people need access to the data. Organizations need data that is manageable, in context, and readily and reliably consumable. In addition to storing time-series data, the PI System’s contextualization capabilities will enable TSOs to create an informational bridge from assets to business databases, calculate key performance indicators and aggregation metrics with analytics, and automatically track key events and excursions.

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