After eight years of operation, the Soške elektrarne Nova Gorica (SENG) power plant successfully completed the first overhaul of the aggregate of the Avče pumped-storage hydropower plant (Avče PHP) which is the only pumped-storage hydropower plant in Slovenia so far. Regular overhauls of the aggregate and equipment are key for ensuring the long-term safety and reliable operation of the power plant. The works were performed by a Japanese company, the Hitachi Mitsubishi Hydro Corporation, which is also the manufacturer of the aggregate. In spite of the fact that additional and unforeseen works occurred during the overhaul, the project was finished ahead of the planned date. Special thanks for the early completion go to the team of SENG staff members and other contractors who contributed to the successful and early completion of the works with their knowledge, work and commitment.
THE EXTENT AND CONDUCT OF THE OVERHAUL
The overhaul of the Avče PHP, which started on 5 November 2018, included the dismantling of the generator and turbine, a detailed inspection and measurements of the installations, renewal of worn-out parts and resolving the detected deficiencies. Turbine and generator maintenance works followed as well as the reassembly. The works mentioned were finished in the second half of March 2019. At the beginning of April all commissioning examinations and tests were successfully performed before the restart of the operation. During the overhaul, modernisation and upgrading of the management system software functionality was performed in harmony with more and more restrictive requirements of the electricity system operator (elektroenergetski sistem, EES) for the system power plant’s operation as the key elements for ensuring the stability of the system.
The overhaul of the aggregate equipment which included the turbine/pump and the engine/generator was performed by the Japanese company HMH Corporation together with a local partner the company RUDIS and the subcontractors Montech and Kovit. Other contractors were the Swiss ABB for the excitation system, ABB Engineering (ABB Inženiring) for the generator circuit-breaker, HSE Invest for the management system, and other subcontractors.
THE IMPORTANCE AND THE ADVANTAGES OF THE AVČE PHP
The Avče pumped-storage hydropower plant (Avče PHP) operating since 2010 is the first power plant of its kind in Slovenia and produces on average 280 GWh of electricity per year. As the share of diffuse sources of energy such as solar and wind power plants increases, the Avče PHP has an increasingly important role in the Slovene electricity system as energy storage with greater capacity which enables the accumulation of the surplus of produced electricity. The advanced technology makes this power plant one of the first among reversible pumped-storage power plants with a variable speed of rotation in Europe. The Avče PHP also ensures, inter alia, system reserves and system regulations that are necessary for ensuring the stability of the operation of the Slovene electricity system.
THE FUTURE IS IN RENEWABLE ENERGY
The increasing share of diffuse renewable sources of energy requires greater storage capacities for the counterbalance of production and consumption of electricity and sustaining the stability of the system. Because of this, the Avče PHP represents one of the key electricity facilities in Slovenia with an even more important role to play in the future.