Proposed technologies will enable greater integration of RES in the transmission and distribution grids and lead to more efficient use of existing infrastructure.

Compensation devices for reactive power control

Compensation devices for reactive power control are a modern means of regulating voltage profiles in the electricity grid. They allow us to ensure a higher reliability of operation of the entire electricity transmission grid and reduce the risk of failure of any basic building blocks of the transmission grid (tramission lines, transformers, etc.), which are vital for the undisturbed operation of both large industrial consumers as well as households. The devices reduce the probability of grid outages and enable quicker recovery of the grid in the event of any faults.

To ensure effective voltage control, an optimal combination of various high-tech advanced devices for the compensation of reactive power and voltage regulation will be incorporated in the Slovenian and Croatian transmission systems. In Slovenia, the SINCRO.GRID - Phase 1 project comprises, among others, the installation of a stationary compensation device with a SVC/STATCOM technology of +/- 150 Mvar at the Beričevo substation, the installation of variable shunt reactor of -150 Mvar and the installation of a capacitor of +100 Mvar at the Divača substation. In Croatia, three devices will be installed – variable shunt reactor of -100 Mvar at the Mraclin substation, variable shunt reactor of -200 Mvar at the Melina substation and stationary compensation device with a SVC technology of - 250 Mvar at the Konjsko substation.

Battery Electricity Storage Systems

Battery electricity storage systems represent an advanced technology in the field of electrochemical storage of electricity. Modern battery cells based on lithium ions (Li-ion) were developed precisely for the needs of the electricity system. Large systemic battery storage systems are comprised of four main sets:

  1. A battery set whose basic building block is a battery cell operating on the basis of Li-ion technology. Individual cells are consecutively and/or parallelly combined into larger units (modules) and equipped in a manner ensuring adequate management and control.

  2. A set for power conversion and exchange, comprised of AC/DC converters, (facility for) transformation to medium voltage, as well as protective and switching elements.

  3. A set for operation and control of the battery storage unit, installed at the level of battery cells and at the level of the entire battery storage system (local SCADA system).

  4. Additional auxiliary systems for heating/cooling, detection and/or automatic extinction of fires, etc.

Within the framework of the SINCRO.GRID - Phase 1 project, two battery storage units with a capacity of 5 MW will be installed at the existing substations of Okroglo and Pekre. Their main purpose is to increase the flexibility of active power and thus enhance adaptation of the electricity system to modern challenges in operation.


Dynamic Thermal Rating System

The purpose of the system for real-time and short-term forecast assessment of power grid operating limits (SUMO) is to assess the marginal capacities of transmission grid components with the help of dynamic thermal rating. The system assesses the transmission capacity for various grid configurations for a period of up to 48 hours into the future, thus improving operational safety and increasing the transmission capacity of components. SUMO is entirely the result of Slovenian knowledge and was developed exclusively for the needs of transmission system operators. A number of scientific and educational institutions, institutes, offices and companies cooperated in its development with their best potentials.

Owing to its knowledge of weather conditions and advanced physical modelling, SUMO enables better utilisation of existing transmission lines and transformers. A particularity of the system is a module for the calculation of minimum load for the purpose of preventing icing of overhead transmission lines.

Aditional hardware and software will be installed in control centers as well as atmospheric measuring instruments on transmission lines.

Virtual cross-border control centre

The virtual cross-border control centre will enable:

  • voltage control and loss optimisation in transmission systems,

  • better control and forecasting of electricity generation from RES, and implementation of tertiary regulation with management of consumption and dispersed generation in Slovenia and Croatia,

  • participation of RES in the provision of ancillary services.


The functionalities mentioned above will be activated with the implementation of new ICT services at the substations and control centres of participating partners.