AVČE Pumped Storage Power Plant on the Soča river

Rudis jointly with the Japanese partners implemented the first Pumped Storage Power Plant (PSPP) in Slovenia

Pumped Storage Power Plants are an important element in developed power supply systems with high percentage of continuous non-variable power generating, where surplus energy occurs during the period of low consumption and simultaneously there are great needs for peak energy. A particularity of the AVČE Pumped Storage Power Plant is that during the period of low consumption and low prices of the electrical energy, i.e. at night and at weekends, water is pumped into the upper water-storage reservoir of volume 2,170,000 m3 (cubic metres)and during the period of increased consumption and high prices of the electrical energy at daily peak hours the electrical energy is generated. At present Pumped Storage Power Plants represent the only possible way of electrical energy storage for the maximum consumption periods, which enables better efficiency of the available water resources.

Rudis jointly with the Japanese partners Mitsubishi Electric Corporation and Sumitomo installed the heart of the AVČE Pumped Storage Power Plant – pump/turbine, motor/generator with the excitation system and auxiliary systems of the Power Plant.

It is the first Pumped Storage Power Plant in Slovenia and the first Reversible Pumped Storage Power Plant of this type in Europe

AVČE PSPP generates 426 GWh of electricity per year. The key advantage of this Power Plant is generating of the so called peak energy from a renewable energy source. Due to adaptability to daily needs of consumers this Power Plant is of especially great importance at provision of stable supply of electricity to the Slovenian electric power system.

Soške elektrarne Nova Gorica d.o.o.
Completion date:
Scope of works:

Designing, supply and assembly of the equipment (pump/turbine, motor/generator with the excitation system, auxiliary systems) of 185 MW AVČE PSPP »on turnkey principle«.


The power house of the AVČE PSPP is of the shaft type.

The power house shaft has a circular cross-section, internal diameter 18 m and depth 80 m.

The Unit is installed at the shaft bottom. The power of pump/turbine is 185 MW in the generating mode and 180 MW in the pump mode.

The Unit is executed so that it enables speed variation from –4 to +4 % of the nominal speed 600 revolutions per minute (VAR-SPEED). 

The advantage of the AVČE PSPP is its execution with asynchronous motor/generator, simplifying speed variation and enabling greater efficiency.

The Unit with variable speed enables better adjustment to circumstances in the electric power system, namely frequency regulating in the network or power modifying in the pump mode operation at greater gross head variations.

Description of works:

Implementation of the project started by elaboration of the project documentation and model test in the year 2005. The principal technological equipment was supplied from Japan. Rudis designed the auxiliary systems and to the greatest possible extent involved Slovene suppliers in implementation.

All equipment assembly was performed by Rudis as well, and the Japanese partners carried out supervision of erection, testing and commissioning. Trial run of the Power Plant and training of the Employer’s staff were carried out in the first half of the year 2010.

Technical data:
  • Maximum gross head: Hb = 521.00 m
  • Useful volume of water: Vu = 2,170,000 m³
  • Installed flow (generating mode operation): Qi = 40 m³/s
  • Installed flow (pump mode operation): Qp = 34 m³/s
  • Turbine installed power: Pi = 185 MW
  • Pumping installed power: Pp = 180 MW
  • Annual electrical energy output: Ean = 426 GWh
  • Annual energy consumption for pumping: Ep = 553 GWh
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