Understanding PSHPP Orlík before its transformation: Inside the technical survey

Understanding Orlík before its transformation: Inside the technical survey

Before a major hydropower modernization can begin, engineers need to understand every detail of the existing plant. At the Orlík Hydropower Plant in the Czech Republic, this means going deep into the existing structures, collecting precise technical data and analysing how the current equipment behaves under real operating conditions.

As part of the preparations for one of the most significant hydropower modernization projects in the Czech Republic, Litostroj Engineering is carrying out an extensive technical survey of the existing facility. The findings will provide a critical foundation for designing and integrating the new turbine technology into the existing powerhouse.

Looking beneath the surface

Modernizing an existing hydropower plant is fundamentally different from building a new one. Engineers must work with structures designed and constructed decades ago, where original documentation alone may not provide all the information needed for today's engineering requirements.

At Orlík, the survey focuses on understanding the existing civil structures, mechanical equipment and hydraulic conditions. During a planned outage of generating unit TG4, Litostroj Engineering teams installed more than 89 measurement sensors to monitor the behaviour of the existing structures and equipment.

The measurements cover areas that are normally inaccessible during operation, including the turbine and the water passage. The existing turbine system handles a water flow of up to 150 m³ per second at a velocity of approximately 15 m/s.

To put this volume into perspective, an Olympic-sized swimming pool would empty in approximately 17 seconds at this flow rate. That is around 3.5 Olympic-sized swimming pools every minute.

Combining laser scanning, measurements and underwater inspections

Understanding the existing plant requires more than conventional inspections. The engineering teams are combining several advanced diagnostic and surveying methods to create a detailed picture of the facility.

The technical survey includes:

• 3D laser scanning: Detailed scanning of the powerhouse, existing equipment and hydraulic passages to capture their exact geometry and dimensions
• Structural and operational measurements: Sensors monitor vibrations, structural loads, pressure in the spiral case and pressure pulsations in the water passage under different operating conditions
• Underwater inspections: An underwater drone helps inspect areas that are difficult to access using conventional methods
• Concrete core sampling: A total of 84 core samples have been taken from selected locations within the concrete structures and sent for laboratory testing to assess their strength, tensile properties and chemical composition

Together, these activities generate hundreds of gigabytes of technical data and provide a comprehensive understanding of the existing plant.

Engineering the transition from Kaplan to Francis technology

The information gathered during the survey will directly support the design of the new generating units. The modernization will replace the existing Kaplan turbines with two Francis turbines and two reversible Francis pump-turbines. This will enable two of the four generating units to operate in both electricity generation and pumping modes, transforming Orlík into a major pumped-storage hydropower facility.

One of the key engineering challenges is to integrate the new reversible Francis pump-turbines into structures originally designed for Kaplan turbines. This requires a detailed understanding of the existing geometry, structural conditions and actual operating loads. The survey therefore plays a crucial role in reducing design uncertainties and ensuring that the new equipment is developed specifically for the conditions of the existing plant.

As Peter Šály, CEO of Litostroj Engineering, explains, understanding how the current generating units load the structures, how vibrations are transferred into the concrete and how pressure behaves throughout the hydraulic system is essential before manufacturing the new turbines begins.

Building the foundation for the future

The technical survey is an important preparatory step in the overall modernization of Orlík. The main construction phase is scheduled to begin in 2027, with completion expected in 2033.

Once completed, the modernized plant will retain its total installed capacity of 364 MW and provide up to 750 MWh of energy storage capacity. By enabling electricity to be stored and returned to the grid when needed, Orlík will play an increasingly important role in balancing the Czech energy system and supporting the integration of renewable energy sources.

For Litostroj Engineering, the project demonstrates an essential principle of complex hydropower modernization: successful engineering starts with understanding what is already there.