Data management between transmission and distribution network operators is the key to effective and secure functioning of the grid and increasing competition, says Eurelectric chief executive Christian Ruby
With the energy transition, the customer moves centre stage. Active customers, increasing penetration of decentralised renewables, new actors like aggregators, the need for flexibility and the development of demand response are all parts of the story. Europe is only at the beginning of the transition. By 2020, 36% of power generation is expected to come mostly from variable renewables, many of them distributed, and this is anticipated to reach 46% by 2030.
In the light of this fundamental change, rules have to be defined, governance conceived and systems reconsidered. Effective co-ordination between transmission and distribution system operators (TSOs and DSOs) becomes increasingly important to ensure cost-efficient, sustainable and reliable system operation and to facilitate markets throughout Europe. Operating the electricity system closer to its limits translates into the need for smarter grids, the precondition for which is the efficient exchange of information and data. Flexibility, which is the prime response to variable renewables, can only be used efficiently for balancing and congestion management if the appropriate data and information are exchanged between TSOs, DSOs and market players.
Well-handled data management between TSOs and DSOs is key to ensuring effective and secure functioning of the grid, as well as facilitating an efficient market. It is important to define roles and responsibilities in the market design, taking into account all interactions (between balancing and congestion management, for example), including competent and reliable data exchanges between TSOs and DSOs arising from this co-ordination.
Congestion management processes (ahead of real time and in real time) in operation are expected to evolve because distributed resources increase both the possibility of congestion and the number of possible remedies.
System operators might be able to avoid or solve congestion in their own perimeter of responsibility either by changing their grid topology or through the action of market players connected to their grids. In doing so, DSOs and TSOs must exchange data and information in all relevant timeframes to ensure safe and reliable operation. It is also important that system operators have the necessary data to check whether certain flexibility bids, when activated, could create congestion in their grids and define limits for or prevent bids activation in areas that will lead to grid constraints.
DSOs are particularly concerned about the possible misalignment of actions between TSOs and DSOs and also between other market players, especially in cases that could lead to a loss of control of the distribution grid and drive inefficient grid expansion. At the same time, TSOs are concerned about their ability to perform efficient balancing of the overall electricity system, ensuring security of supply and fair market functioning. With the increasing amount of (renewable) generation facilities in distribution networks, both TSOs and DSOs would like to unlock as much of the potential of these distributed resources as technically possible.
The growth of generation in the distribution networks – together with the empowerment of consumers through markets and technologies and the participation of these new assets in the balancing market – are making the system even more complex. Apart from balancing at TSO level, balancing the local grid becomes a focal point, and the central grid an exchange, creating further complexity and affecting the overall co-ordination of the distribution system. This might affect the operation, quality and cost of the service. In this sense, TSOs carry the responsibility of balancing to maintain system frequency, while DSOs have to play a crucial role in ensuring system stability and integrity at local level. DSOs are expected to play a more active and integrated management role.
For balancing, TSOs will need to activate bids on the DSO grid. In these cases, DSOs should receive relevant data that allows them to assess the impact of such an activation. If potential constraints are identified, DSOs must make the aggregator, the party responsible for balancing or the TSO aware of the potential impact, so further measures can be taken.
From a DSO point of view, some balancing actions could be devolved to them to procure balancing services on their networks to support the TSOs as a subsidiary activity. This could help manage the impact of distribution generation within specific parameters as set out by the TSO. This assures the TSO that balancing interventions are occurring on the DSO network without the TSO needing to check with the DSO every time a balancing action is needed on the DSO network.
Flexibility connected to the distribution grid could of course contribute to system balance, and then efficient data exchanges, IT interface operability and market design should ensure that interferences with congestion management are dealt with and are under control.
To conclude, it is important to recognise the energy system as one complete system instead of several separate systems like TSO grids and DSO grids. When looking at the system as a whole, it is clear that all parties involved should work together to achieve a safe and reliable electricity system and social welfare optimisation though regulatory oversight. This co-operation has started well with discussions among TSOs and DSOs, but it needs further work to function accordingly.