Scientific paper ID 2748 : 2025/3

Over the past decade, the number of installed photovoltaic power plants connected to the electricity system has increased significantly. This has led to a significant increase in the production of electricity from renewable sources, but at the same time has caused fundamental changes in the form of the daily, weekly, monthly and annual load schedules of the electricity system in the country. The imbalance in electricity production, caused by large surpluses during the day and its shortage during the dark part of the day, may lead to a collapse of our electricity system. The problem is further exacerbated by the non-operating units in the Chaira Hydroelectric Power Plant. The combination of overproduction and insufficient electricity storage resources convincingly proves the need for reserve capacities for accumulating electricity.

In search of ways to accumulate electricity, including supporting the balancing of the load schedule, an idea arose that is described in the report. A specific terrain was noted in the Kresna Gorge area, which has specific features ensuring profitability in the construction of a Pumped Storage Hydroelectric Power Plant. An analysis of the terrain was made and approximate calculations of a future HPP site were made. Data on the minimum water quantities of the Struma River were obtained. Calculations have been made to determine the height of the dam wall, the flow rate in operating mode, the electrical power, the maximum possible amount of accumulated energy per day and per year at the corresponding minimum flow rate. Calculations have been made at four times the height of the wall. A comparison of the data with existing energy facilities in the country has been made.