Transmission system control includes planning activities and activities in real-time, but also coordination of transmission system operators at the regional level and smart grids concept implementation.

Most important planning activities include as follows:

• Contracting ancillary services;
• Preparation of outage plans;
• Calculation of cross-border transmission capacities;
• Preparation of power system operation plans;
• Development of model and security analysis;

Entering into ancillary services agreements, TSOs provide power capacities for: 1) frequency regulation and power exchange (primary, secondary, tertiary), 2) voltage regulation and 3) system recovery after a blackout.

Outage plans for works on network elements are first developed for the Southeast Europe region, while outage plans for our transmission system are further harmonized accordingly in cooperation with all transmission system users.

In order to enable international power exchange, transmission system operators make calculations and agree on cross-border transmission capacities for each border and direction. Capacities calculated in this manner are then allocated to electricity suppliers under special rules.

Demand and technical loss forecasts are a first step in the development of daily schedules for the power system. These data are combined with the data from the balance groups’ schedules relating to power demand, generation and exchange. The schedules must also predict a contracted reserve for load-frequency control.

Grid models of individual transmission systems are produced to ensure the security of system operation.  Security calculations are conducted on a coupled grid model for the whole Continental Europe interconnection. If the analysis indicates that the security criteria have not been met, then modifications of transmission network topology or engaging production facilities would be required (so-called redispatching).

Most of the planning activities are coordinated regionally through a regional security coordinator.

Real-time transmission system operations includes the following main activities:

• Supervision of transmission system operation;
• Secondary and tertiary regulation;
• Voltage control;
• Implementation of outage plans and issuing work-related documents;
• Disturbance clearing.

Transmission system monitoring and control are carried out by advanced and integrated information system, most important including:

• SCADA/EMS system which exchanges and processes data from the transmission system facilities, transmission system users and neighboring transmission system operators – this system includes advanced applications which enable automation of the most important processes (secondary regulation, system security monitoring …);
• MMS system which provides the necessary records for market transactions for the needs of the balance mechanism and the intraday changes in the transmission system operating plans;
• WAMS system which monitors the stability of the transmission system operation;
• SCALAR system which monitors atmospheric electrical discharges to protect the people during works on the grid and preparing the system for operation in unfavorable weather conditions.