Hydraulics for Norway's most extensive upgrade of hydro power 

About the project: Modernization of Vamma 11 

Hafslund has chosen ANDRITZ to upgrade the turbine-generator unit (unit 11). The work includes dismantling, reassembly, testing and commissioning, in addition to model testing and delivery of new components.  

A key part of the upgrade is the design and delivery of a new Kaplan impeller with a water-filled hub, which both improves efficiency and contributes to a better environmental profile.

Planned stator assembly on site is planned for the first half of 2026 and commissioning of the fully upgraded unit is expected in early 2028.

Why Servi was chosen

Servi was chosen as a supplier based on:

• Space and maintenance-saving accumulator system (fewer, larger units / specially adapted layout)

• Good quality and professional expertise. The cylinder factory in Rissa has supplied cylinders to Andritz for 40 years with good experience - a total of 27 servo cylinders (24 pcs. + spare)
  
  
• Compact and service-friendly block solutions - 24 pcs. servo valves mounted in valve cabinets
  
  
• Low-noise pump solutions that fit well in a power station environment 

In addition, this is an upgrade of a plant where the existing hydraulics are from the 70s - and then the right modernization strategy becomes extra important.   

What should the hydraulics do? 

The hydraulic system must regulate 24 servo cylinders simultaneously, and ensure precise control of water volume and speed towards the impeller – continuously adapted to the power requirement. 

This places strict demands on:

• stable pressure and flow during dynamic load changes
  
  

• safe and predictable function during quick closing and unloading

• verifiability: That all functions can be documented through testing 

Main delivery from Servi

1. Hydraulic power unit (HPU) – capacity and robustness

• 4 main pumps with high capacity (stated as 175 l/min per pump)
• Large tank solution (stated around 10,000 liters, stainless material)
• Working pressure stated at 140 bar, with design and test pressure defined in specification

2. Valve and block solutions mounted in valve cabinets for safe and precise regulation

• Blocks for guide vane control
• Solutions for quick closing / safe function and necessary verifications
• The valve cabinets are mounted outside the guide vane control servos. Each valve block has 2 pcs. servo valves that control 2 servo cylinders.

3.   Accumulator and gas cylinder solution (space and maintenance)

• Specially adapted accumulator system and gas cylinders for more compact installation and lower maintenance requirements

4. Servo cylinders

• Total 27 servo cylinders (24 pcs. + spare)

5. Pressure oil depressurization system

Specially adapted pressure oil solution for existing support bearings

How Servi works in modernization and upgrade projects
 

Regardless of whether the delivery concerns a single component or a complete, customized system, this is the method we use:

1. Needs and risk profile
    
   We map functional requirements, response times, available space, maintenance principles and safety/verification requirements.
   
   
   
2. Design for operation and maintenance
   In the Vamma project, this means, among other things, compact block solutions and an accumulator system that reduces complexity and space requirements.
   
   
   
3. Construction and quality in the workshop
   
   The system is built with clear marking and documentation, so that assembly and later service are predictable.
   
   
   
4. Testing (FAT) 
   Everything is tested within specification, with function tests and pressure tests.
   
   
   
5. Documentation and traceability. Hydraulic diagrams, parts list tracking, data sheets and FAT protocols are part of the delivery.