Reasons behind this project

Due to the massive development of digital controls and power electronic devices, replacing conventional sources, loads and network devices (FACTS, HVDC, BESS), the study of the stability of the system becomes more and more complex. Existing and new stability phenomena are impacted by those changes, and requires appropriated data, methods, and tools.

Other CRESYM projects such as Harmony and BiGER, tackle existing modelling assumptions used for stability and propose new methods, but real network cases are required to validate those future solutions.

In this respect, the Solvenian grid is a good case. it will experience in the next 10 years a high growth of electricity demand, decreasing inertia due to a high level of RES penetration (40% in energy coverage in Slovenia), increasing cross border exchanges. And as a result, stability risks must be carefully assessed in planning studies, with novel methodologies.

Project objectives

1. To identify frequency and converter-driven stability challenges in the Slovenian transmission system.
2. To develop and implement RMS and impedance models of the Slovenian grid.
3. To apply and validate new methods for assessing ROCOF risks and converter-driven instability.
4. To support TSOs in defining future-proof stability criteria and mitigation strategies.

Project members

LaRISA is a common project, performed by University of Ljubljana under the supervision of ELES.

Project deliverables

• Dynamic models:
  • validated and tested RMS dynamic model of the Slovenian electric power grid (private)
  • validated and tested impedance-based model of the Slovenian electric power grid (private)
• Reports:
  • • State-of-the-art on harmonic instability – chapter 2 (private)
    • Operational procedures and criteria for stability assessment- chapter 6 (private)
    • Stability analysis – chapter 5 (private)
• Papers:
  • Leopold Herman, Jure Lokar, Tadej Škrjanc, Urban Rudež, Boštjan Blažič, “Stability of the Slovenian power system with the increasing share of renewables energy sources”, CIGRE-CIRED 17th Conference of Slovenian Electrical Power Engineers, 2025 (private)
  • Jure Lokar, Boštjan Blažič, Leopold Herman, “Converter-driven stability in Slovene Transmission grid on a case of High share of converter-interfaced devices”, CIGRE-CIRED 17th Conference of Slovenian Electrical Power Engineers, 2025 (private)