A major overhaul and upgrade were needed as the plant's machinery and auxiliary equipment had reached the maximum operating service life

The Puntarikoski hydropower plant (built in 1957 in Kontiolahti) was last modernised in the late 1980s.

“The renovation was necessary because there were already many breakdowns in the old power plant, which meant that the number of maintenance visits increased. Besides, it was already hard to find suitable spare parts for the old equipment,” says Vesa Talonpoika, Project Manager of VEO Hydropower, who was responsible for the renovation of the Puntarikoski hydropower plant.

During the years 2016–2018, energy supplier Pohjois-Karjalan Sähkö invested five million euros to keep the plant productive. The investment focused on modernisation and installing new equipment. VEO delivered new switchgear needed for Puntarikoski’s electrical distribution system as well as machinery and plant automation systems, containing both turbine and excitation systems. The Croatian company Koncar delivered the generator and the Slovenian company Litostroj Power delivered the turbine.

The space-saving solution

Since Puntarikoski is an old power plant, it was important to pay attention to space limitations.

“Available space is almost always a challenge when modernising an old power plant. Although Puntarikoski is not the smallest one I have seen, we still needed to do some serious planning work to get all the necessary equipment to fit into the building,” says Talonpoika.

Because the Puntarikoski automation system integrates the control of the ventilation and cooling system of the power plant building, there was no need for a separate IV control system which saved on space. Another space-saving solution was achieved through Generator Commander, an innovation developed by VEO and Arcteq. Generator Commander combines generator protection, synchronisation and magnetisation in one device.

“The device uses 86 per cent less space than the old equipment. Thanks to the simple design, it is clearly more beneficial compared to traditional devices,” Talonpoika notes.

The original technology in the old Puntarikoski power plant no longer fulfilled today’s requirements. In the overhaul, the original solutions were replaced by modern automation systems, whereby the output and input circuits were moved from the process station closer to the regulating unit. Such an implementation is called distributed I/O.

“We strived to utilise distributed I/O as much as possible to reduce the number of cables required for the plant’s systems and to minimise the fire load they cause. This implementation method reduces the amount of installation and testing work at the plant, and is thereby a cost-effective solution,” clarifies Jukka Kelloniemi, from VEO’s hydropower automation team.

"The renovation was necessary because there were already many breakdowns in the old power plant, which meant that the number of maintenance visits increased. Besides, it was already hard to find suitable spare parts for the old equipment."

With the turbine governor to the new market

According to the customer’s wishes, the automation solution was implemented with a Siemens S7-1500 system. To support the qualities of the Siemens system, VEO developed a new hydropower automation solution for the project. At the same time, the turbine governor was updated to suit both the Siemens S7-1500 system and future regulations from the transmission system operator.

“The installation of the turbine governor revealed that changes were needed because of the structure of the old plant and the behaviour of the waterways. For the test run to run smoothly we needed to modify the operation of the automation to match the specific features of the plant,” Kelloniemi Explains.

The Puntarikoski plant’s original electro-hydraulic turbine governor was designed solely for power control. Now with the new turbine governor, the machinery also has the potential to participate in the control reserve market in addition to traditional energy production.

“This adds value to the productivity of the Puntarikoski plant, especially when the balancing of electricity production and consumption is further emphasised in the future. With Fingrid’s current rules, even smaller units can become part of the reserve maintenance market,” Kelloniemi points out.

A successful outcome

The aim of the revamp was to increase the usability of the power plant and to improve the information system. These goals were reached, and Jari von Becker, Power Plant Manager of Pohjois-Karjalan Sähkö, is pleased with the outcome.

“The Puntarikoski hydropower plant was almost completely rebuilt, so this was a huge project for us. There is no such thing as a perfect project, since there are always surprises that need to be corrected. However, I believe that the outcome is most important and therefore, as a whole, Puntarikoski was completed with distinction. We also kept to our timetable, which is always positive. This was helped by the fact that we have worked with VEO for decades. We know each other’s ways of working, so the cooperation runs smoothly. Now that we have been following the operation of the revamped power plant for some time, I can say that everything looks good”, says Becker smiling.

“When the customer is satisfied with the result, the project can also be considered successful from the supplier point of view,” Kelloniemi adds contentedly.