Transmission System Operation & Control Department (TSOCD)

The Transmission System Operation & Control Department (TSOCD) is responsible for the supervision, control and operation of the Hellenic Electricity Transmission System (HETS), with the mission of assuring the uninterrupted supply of the country with electricity, while always meeting electricity transmission quality and performance criteria. It moreover participates in the electricity market scheduling and operation.

The TSOCD consists of two branches: one responsible for managing the operation of the System and the operation of the electricity market through the Energy Control Centers (ECC) and the other for managing the Short-term Scheduling of Operation and market. Operation of the HETS is carried out in real-time conditions, after first studying and taking into consideration all those factors that affect or can affect it. 

In more detail, the Operation Department is responsible for the following activities:

  • Supervision - Control of Transmission Network Operation (Market operation)
    Conducted by ECCs in real time, ensuring the safe transmission of energy from production points to consumption points at each point in time, using all available tools and processes.   
  • Load - frequency control
    Conducted in real time at the national ECC, using appropriate computation tools and their applications, such as the EMS (Energy Management System) and MMS (Market Management System).
  • Production - Demand Balancing 
    Conducted by the National ECC in real time, with the help of the available reserves and market mechanisms. This balancing is carried out also on a short-term horizon by the Energy Scheduling Sector.
  • Voltage control
    Conducted by Regional ECCs, using all available means (system assets, unit reactives, Distribution capacitors), to achieve the required voltage quality and safety characteristics.
  • Network component handling 
    HETS components are handled by the Regional ECCs, based on the safety rules, and are performed generally by operators-supervisors in accordance with ECC orders or on occasion by ECC remote control.
  • Works at the HETS 
    No work is performed at the HETS without the agreement of the ECCs. Regional ECCs ensure isolation of HETS components where works will be performed and issue the necessary Work Licnses to the work Beneficiaries. 
  • Incident Management
    The ECC Operations Supervisors manage any incident that affects the status of the System in order to restore it to normal operation as soon as possible. 
  • Common network model
    Develops the common network model used to analyse load flows and stability. Cooperates with the respective Regional Security Center for receiving necessary safe operation services.
  • National / International coordination with Operators and Authorities
    Collaborates with Authorities and Bodies (Operators, RSC, ENTSO-E, etc.) nationally and internationally where required. 
  • Security Analysis
    Conducts security analysis for potential situations of the HETS.
  • Congestion management
    Manages congestions wherever they are observed, with the goal of normalizing them.
  • Capacity Calculation
    Taking security criteria into account, cross-border transactions with neighbouring operators are calculated and harmonized.
  • Operation Scheduling
    Schedules operation in the short-term, to ensure the security of the supply of HETS.
  • Electrification of new equipment
    Carries out the electrification of new equipment connected to HETS, in collaboration with all parties involved, observing all the necessary procedures for the safety of people and equipment.
  • Maintenance scheduling
    Schedules and coordinates the isolations of HETS components in order to perform their maintenance and the necessary expansions of HETS. Isolations are scheduled with the aim of ensuring the uninterrupted operation and supply of the HETS.
  • Scheduling of International Interconnections
    Prepares the scheduling of the isolations of the country's interconnections in cooperation with neighbouring Operators and stakeholders.
  • Preparation, maintenance and issue of HETS Single-line diagrams
    Draws up, updates and keeps a record with the last updated single-line diagrams of all substations and High Voltage Centers (HVC) of HETS, depicting the elements of the System and their respective connections. 
  • Substation Supervision - HVC
    The TSOCD, through the Supervision Sector, manages the System's Operators-Supervisors. Operators-Supervisors supervise, inspect and control the Substations and the HVCs of HETS, inform the Transmission System Maintenance Department and the Regional ECCs about the relevant issues of the Substations or HVCs and carry out operations at the System components in accordance with the ECC orders and the safety rules.   
  • Protection
    Planning, designing and monitoring of electrical protection devices and schemes and relevant applications, arrays and automations to ensure the uninterrupted operation and the improvement of the reliability of HETS.                                   
  • Training
    Ensures that the ECC operating staff receive specialised training and certification.
  • Issue of Daily Reports
    The TSOCD issues a number of reports which are either published as they are or are used in studies. The ECCs issue Operations Anomalies Reports for each incident or task at the HETS.


The TSOCD is the Company's Department that operates continuously and ensures the seamless and quality operation of the HETS, on the basis of the Electricity Market rules at any time regardless of conditions (bad weather, component failures, etc.), to provide the commodity of electricity across the country. For example, it handles incidents due to fires which put at risk the smooth operation of the System, manages particular modifications to the System to complete large public interest projects, such as National Highways, new projects (connection of the Cyclades, etc.).

The TSOCD represents IPTO by participating in the bodies and activities of ENTSO-e. 

TSOCD, apart from its work related to its responsibilities, also serves as a consultant in the optimisation of the HETS planning, and the optimisation of the available resources and their future planning, utilizing their experience from the real-time operation of the HETS.

The TSOCD, taking into consideration the new circumstances of the framework and procedures required for compliance with the new Target Model, assists with the scientific knowledge and experience of its members towards the smooth transition to the new Electricity Market model, with the same impartiality and responsibility it has demonstrated to date and aspires to continue to be the steady pillar supporting the further growth of the company. 

The Department has also had a pivotal role in the creation of the new Regional Security Coordinator in Thessaloniki.


22 Asklipiou Str.   GR 145 68 Krioneri Athens 

Ziogas Vassilios 


Tel  +30 210 6220738 - +30 210 6294232 

Fax  +30 210 6220070 

E- mail