Two of Finland’s major hydro power plants, located in the freezing Arctic Circle, are now SF6 ‘greenhouse gas’ free, thanks to a turn-key generator circuit breaker retrofit that gears them up for a more resource-efficient future.
ABB customer, Kemijoki Oy, is one of the most important players in Finland’s renowned carbon neutral electricity system – responsible for balancing half of the country’s grid output – as well as being the leading provider of hydro and regulating power in the colder North and East of the country.
Kemijoki Oy
Operating 20 power plants, Kemijoki Oy can adjust the production of safe and secure hydropower by the second, providing essential energy for Finland’s increasingly clean grid.
The plants – Matarakoski, which was completed in 1995 and Ke-lukoski in 2001
The plants – Matarakoski, which was completed in 1995 and Ke-lukoski in 2001 – have an 11 MW output and power some 10,000 family homes between them.
They had been running on their original SF6-based HPA circuit breakers and despite being technically competent, the aging circuit breakers were no longer in line with Kemijoki’s strict environmental diversification program or the latest global Dual Logo Standard.
Lack of available spare parts an issue on breakers
Lack of available spare parts was also becoming an issue on breakers that had been in commission for around 30 years.
However, completely overhauling the existing switchgear operation wasn’t financially sustainable and down-time had to be at the absolute minimum because of the key part Kemijoki hydropower plays in the country’s energy security and production.
ABB offers a retrofit solution
ABB’s Electrification Service team was able to provide a retrofit solution that saw downtime reduced to hours rather than weeks, thereby ensuring the power was kept on without any disruption.
A customized 12kV version of the market leading MV VD4G vacuum circuit breaker family was specified, which clears potentially harmful short-circuit faults in tens of milliseconds, thereby preventing severe damage and lengthy plant downtime.
Resin-insulated vacuum interrupters
Resin-insulated vacuum interrupters guarantee higher protection of the core components
Resin-insulated vacuum interrupters guarantee higher protection of the core components and it’s a complete asset protection solution that safely navigates fault conditions with delayed current zeros and severe transient recovery voltages.
Jarkko Virtanen, the Vice President (VP) - Electrical and Machinery Technology at Kemijoki Oy, said: “Good operational preconditions at the river are a prerequisite for cost-effective hydropower production, so ABB made it very easy for us with a plug and play model that we did to instruction to save valuable time, money and resource.”
Retrofit solution ensures reduced downtime
He adds, “Compared to a full overhaul of the complete medium voltage switchgear, we saved almost a month of downtime with the retrofit – taking just hours rather than several weeks – and in an industry where 24/7 power output is expected that’s a lot of vital energy production and lost revenue saved.”
Jarkko Virtanen continues, “We also have a much more reliable operational procedure, because it handles the currents much better, and cost effectively extends the life cycle of our generator applications by at least another 20 years.”
ABB and Kemijoki Oy partnership
Sixten Holm, the Business Development Manager for ABB Electrification Service division in Finland, said: “We have a long-standing and collaborative partnership with Kemijoki Oy and it works because we know and trust each other. They welcomed the input and expertise of our Service division and together we arrived at a solution that brings much higher plant reliability and meets stricter safety standards.”
Sixten Holm adds, “VD4G represents ABB’s optimum solution for generator applications where the highest possible protection is needed, especially in case of critical short-circuit conditions, while the retrofit’s smaller footprint provides a cost-optimized solution that saves valuable and essential time during site commissioning.”
Retrofit solutions planned for other power plants
Now that a successful blueprint is established, retrofit solutions are planned for other power plants, while the open switchgear system of Kemijoki’s larger and more heavy-duty power plants are being considered for the latest in DPA pressure breakers.
