Technology



Balancing markets

In real-time, the BRPs might face imbalances. These imbalances are calculated for the settlement periods which is a quarter of an hour in Belgium. This means that their net quarter-hourly sum of injection, off-take and power exchange trade in the balancing group, differs from the nominated value. The grid operator will resolve these imbalances by activating reserve power that was contracted before hand – physically this activation results in a reduction/increase of supply and demand. This reserve power is contracted by the TSO on a new type of markets, the so-called reserve market. Here the TSO buys different reserve products that are offered by other market players such as electricity generators and suppliers. The most common reserve products are discussed below.

conventional reserve power suppliers

Classical reserve products were historically offered by large generation plants or large industrial consumers. Power plant operators can offer a certain capacity Elia can use for upward regulation. This is needed when real-time supply in the power system is not sufficient to meet the overall demand. On the other hand, they can also set up a contract for lowering their output in case of an excess of electricity in the grid. Large consumers can make deals to lower or increase their consumption when Elia sends a request. Such controlled steering of demand is called demand response. (It is often referred to as demand side management as well, which is however technically not the fully correct term in this context.)

Reserve Power Type (Belgian name) Common European name Explanation
R1 (primary reserves) Frequency containment reserve (FCR) Kicks in automatically in a matter of seconds (fully activated within 30s) after the deviation from the reference frequency (50Hz in Europe). Its aim is to contain the deviation to avoid system collapse.
R2 (secondary reserves) Frequency restoration reserve (aFRR) These reserves are controlled centrally by Elia to restore the frequency back to its reference value. The reserves need to be fully activated within 7.5 min.
R3 (tertiary reserves) Replacement reserve (mFRR) The replacement reserves are meant to free up the R2 reserves after the frequency has been restored. They are controlled manually and activated locally. They are important to solve important imbalance and congestion problems, active in a time range from minutes to hours. R3 needs to be fully activated within 15 min.

Pools of small decentralised generation and demand find their way to the reserve markets

Since a few years, Elia allows smaller controllable loads and production units which are connected to the distribution grid to take part in the tertiary reserve market. Aggregators like Next Kraftwerke pool generation and demand of different sizes and technology in a so called virtual power plant (VPP). The single units in this VPP are then controlled in a coordinated manner, with the result that the overall pool can deliver reserve power with the same quality as large central power plants – and this even at a more competitive price. Today, Elia allows aggregators to offer primary reserve power and a specific product of tertiary reserve power which was specifically designed for demand response. There is still a specific product in the R3 category which cannot be accessed by aggregators, but more importantly the R2 reserve power market is still fully closed and only served by less than a handful of providers with larger central units. However, Elia is already investigating how also these remaining oligopoly markets can be opened to nondiscriminatory competition.

To make this possible, the grid operator introduced a new type of reserves called the R3 dynamic profile. This enables distributed energy generators such as wind parks and biogas CHPs, flexible loads of smaller industrial players or households and storage to offer their flexibility.

Together with the new type of reserve, Elia introduced a new market role: the balancing service provider (BSP). They are the entity that offer the flexibility of a unit or load in the reserve market to parties that request flexibility services, the TSOs or DSO. Often the flexibility of several distributed units is aggregated by one BSP, which is then called an aggregator.

R1 up

Product Activation Direction Reaction Speed Practical Implications
R1 up
  • upward regulation
  • increase in generation or decrease in consumption
30 seconds
  • About 100 times activated per year
  • On average 30s activation
  • Limited power reduction
  • Always within safe operation range

R1 down

Product Activation Direction Reaction Speed Practical Implications
R1 down
  • downward regulation
  • decrease in generation or increase in consumption
30 seconds
  • About 100 times activated per year
  • On average 30s activation
  • Limited power reduction
  • Always within safe operation range

R1 sym

Product Activation Direction Reaction Speed Practical Implications
R1 sym Flexibility in both directions within seconds
  • Continuous activation up and down
  • Up and down on average compensate one another

R3 DP

Product Activation Direction Reaction Speed Practical Implications
R3 DP
  • Downward and upward regulation
  • Production increase or consumption decrease
15 minutes or more
  • Limited number of activations: maximum 8 times per month
  • Maximum activation time of 2 hours
  • Maximum 12 hours in between activations

Free bids (R3)

Product Activation Direction Reaction Speed Practical Implications
Free bids (R3) Flexibility in both directions 15 minutes
  • Flexibility offered day ahead
  • No reservation but activation price