Transmission system operator is responsible for the security and stability of the electric power system. This includes ensuring a constant balance of the electric power generated and consumed. Deviations from the balance cause system imbalance. The indicator of power system balance is the electric power frequency. In the Baltic states, under normal operation state, the frequency should be within the range of 49.95 to 50.05 Hz.
Transmission system operator ensures the electric power balance using a regulation service. There are three types of system regulation:
- Frequency containment reservers (FCR) - automatic regulation of generation and/or consumption to avoid momentary frequency deviations.
- Frequency restoration reserves (FRR) - automatic regulation of generation or consumption if the frequency is not restored within a few minutes from the employment of the FCR. Upon employment of the FRR, the FCR are released for the use of further disruptions.
- Replacement reserves (RR) - manual frequency regulation in generation and/or consumption if additional regulation is required after the FRR.
The Baltic states are currently operating in a single synchronous zone with the Unified Power System of Russia - UPS, according to the mutual agreement between BRELL states (Belarus, Russia, Estonia, Latvia and Lithuania). According to the cooperation agreement:
- FCR and FRR activations are provided by the Russian power system;
- RR activation is provided also by Baltic power systems as transmission system operators are required to ensure that imbalance of each power system is within a specified range.
Transmission system operators manage system imbalance by activating reserves offered by balance service providers. These energy products are exchanged via balancing market operated by transmission system operators.
To facilitate equal opportunities to all Baltic balancing market participants and to comply with European Commission Electricity Balancing guidelines, Baltic transmission system operators agreed to organize a common balancing market. Common Baltic Balancing market started operating on 1st of January 2018. The market is operated by Baltic transmission system operators: Elering AS, AS Augstsprieguma Tīkls and LITGRID AB, who have jointly developed harmonized market framework established by: Balancing Market Rules; Imbalance settlement Rules; Terms and Definitions.
To participate in the Baltic Balancing Market, a market participant have to have an ancillary service agreement with the transmission system operator. Read more here.