Electricity System Operator

Electricity System Operator EAD (ESO; Bulgarian: Електроенергиен системен оператор ЕАД) is the Bulgarian state-owned transmission system operator (TSO) headquartered in Sofia. It is the entity responsible for the unified operational coordination and management of the electricity system of the Republic of Bulgaria, ensuring the operation, maintenance, repair and reliable functioning of the national electricity transmission network. ESO is 100% owned by the state-owned Bulgarian Energy Holding (BEH), and it operates under the Bulgarian Energy Act and EU Directive 2003/54/EC, holding a 35-year licence issued by the State Energy and Water Regulatory Commission in 2006. ESO's core mandate covers three main activities. First, it maintains and operates the transmission network, which as of 2022 comprised high-voltage power lines with a total length of 15,384 km (65% at 110 kV, 18% at 220 kV and 17% at 400 kV), including interconnections with neighbouring countries, as well as 297 substations (including 261 step-down substations to medium voltage). Second, it carries out operational management, control and coordination of the electricity system's operating regimes, including parallel interaction with the electricity systems of other countries in the Continental Europe synchronous area. Third, it administers the electricity market, registering and facilitating bilateral contracts on the liberalised market, organising balancing energy and acting as a party to all balancing energy transactions. ESO plays an important role in the liberalised segment of Bulgaria's electricity market, providing the link between the regulated and liberalised sectors. Its operational work is carried out mainly through the Electricity Transmission Directorate and the Central Dispatch Directorate. The Electricity Transmission Directorate maintains and technically controls the transmission system through 13 territorial units (transmission districts), some of which are further divided into 15 transmission sub-districts, so that each administrative region corresponds to a district or sub-district. The Central Dispatch Directorate provides centralised operational management, control and coordination of the electricity system regimes — frequency, voltage and exchange and reactive power regulation, changes in transmission network configuration, and coordination with the parallel operation of the system with those of neighbouring countries. It also organises and administers the electricity market, providing the technical conditions for energy transmission under contracts between market participants. Four territorial dispatch centres report to the central management: West (Sofia), South (Plovdiv), North (Pleven) and East (Varna). As Bulgaria's TSO, ESO is a key participant in the European electricity market framework, cooperating with the electricity systems of the countries of the Continental Europe synchronous area and working towards the integration of the European energy market. Its public website provides operational and historical generation data, cross-border physical flows, frequency information, transmission capacity usage, energy balance reports, system error (Area Control Error) data, connection capacity information, balancing market forecasts and access to the ENTSO-E transparency platform.

The national electricity transmission system of Bulgaria has its origins in the mid-20th century, when it formed part of various administrative structures that combined the management of the entire electricity sector. From the end of the century, a reorganisation of the system began in order to enable the liberalisation of the markets for the production and consumption of electricity. To this end, steps were taken to organisationally separate transmission activity from the production and distribution of electricity. In 2000, transmission activities were separated into the High Voltage Networks Enterprise within the National Electric Company (NEC). On 1 April 2007, these activities were fully separated from NEC into ESO, which was directly owned by the Bulgarian Energy Holding, created shortly afterwards. ESO thus became the independent transmission system operator of Bulgaria, 100% owned by the state through BEH. ESO carries out its activity on the basis of the Energy Act and Directive 2003/54/EC, for which purpose it holds a 35-year licence issued by the State Energy and Water Regulatory Commission in 2006. Over the following years, ESO consolidated its role as the operator of the national transmission grid and as administrator of the electricity market, while also integrating with the wider European electricity system. As of 2022, its transmission network comprised high-voltage power lines with a total length of 15,384 km (65% at 110 kV, 18% at 220 kV and 17% at 400 kV), including interconnections with neighbouring countries, as well as 297 substations (including 261 step-down substations to medium voltage). ESO plays an important role in the liberalised part of Bulgaria's electricity market and provides the link between the regulated and liberalised sectors. On the free market, it registers and assists in the implementation of bilateral contracts. ESO organises balancing electricity (coordinating temporary differences between available supply and demand) and is a party to all balancing energy transactions. It also cooperates with the electricity systems of the countries of the Continental Europe synchronous area and works towards the integration of the European energy market. Operationally, ESO's main activity is carried out by the Electricity Transmission Directorate and the Central Dispatch Directorate. The Electricity Transmission Directorate maintains and technically controls the transmission system through 13 territorial units (transmission districts), some of which are further divided into 15 transmission sub-districts, so that each administrative region corresponds to a district or sub-district. The Central Dispatch Directorate provides centralised operational management, control and coordination of the electricity system regimes — frequency, voltage and exchange and reactive power regulation, changes in transmission network configuration, and coordination with the parallel operation of the system with those of neighbouring countries. It organises and administers the electricity market, providing the technical conditions for energy transmission under contracts between market participants. Four territorial dispatch centres report to the central management: West (Sofia), South (Plovdiv), North (Pleven) and East (Varna).

• 2022

  ESO's transmission network comprised 15,384 km of high-voltage lines and 297 substations.

• 2007

  On 1 April, transmission activities fully separated from NEC into ESO, owned by the Bulgarian Energy Holding.

• 2006

  ESO receives a 35-year licence from the State Energy and Water Regulatory Commission.

• 2000

  Transmission activities separated into the High Voltage Networks Enterprise within the National Electric Company (NEC).

Bulgaria's sole state-owned transmission system operator, acting as the backbone of the national electricity system and the link between the regulated and liberalised electricity markets.

• Electricity transmission network operation and maintenance

  Maintenance and operation of high-voltage power lines and substations, including interconnections with neighbouring countries.

• Operational management and system control

  Centralised operational management, control and coordination of the electricity system, including parallel interaction with other countries' systems.

• Electricity market administration

  Registration and facilitation of bilateral contracts, organisation of balancing energy, and participation in balancing energy transactions.

1. 1ESO.BG - Електроенергиен Системен Операторeso.bg
2. 2Wikidata: Electricity System Operatorwikidata.org
3. 3Wikipedia (Bulgarian): Електроенергиен системен операторbg.wikipedia.org