Outdated technology replaced with Valmet turbine automation

The power plant in Hovinsaari consists of bio and combined cycle power plants, as well as an auxiliary boiler.

It produces a significant amount of the district heat used in Kotka. In addition, the power plant supplies process steam to the Danisco Sweeteners Oy factory and electricity for the national grid. Kotkan Energia employs approximately 100 people.

The bio power plant produces approximately 50 MW of district heat, 10–15 MW of process steam and 15 MW of electricity. Fuels consumed by the power plant include industry by-products, forest-based fuels, recycled fuels and peat, if necessary. The nominal output of the generator is 25 MW.

The Valmet DNA automation system is a crucial part of the Hovinsaari power plant.

Electrical and control technology expert Antti Roponen from Kotkan Energia is in charge of the development of the electrical

automation systems and any related investment projects. "In terms of automation, the Hovinsaari plant is a sizable and challenging entity, as the plants and pumping plants have been located around the city. They are all controlled from within the main power plant control room," he says.

Integrated steam turbine automation

One of the latest investment projects includes the replacement of the outdated turbine automation of the bio power plant with modern technology. The previous ABB VAX turbine control system dating from the 1990s had come to the end of its life cycle.

Antti Roponen in the control room

"Cooperation started when we made the deal with Tom Bäckman," Roponen says. Tom Bäckman, the Business Manager in charge of turbine automation at Valmet, nods: "We have achieved the benefits of turbine automation, transparency and availability. In addition, steam turbine automation has been integrated seamlessly with the Valmet DNA system in the main control room."

The delivery also included overspeed protection for the turbine, as well as turbine protection with HiMatrix and generator protection, synchronization, voltage control and condition monitoring with Valmet DNA Machine Monitoring. With the help of condition monitoring, the plant receives vital information on e.g., any turbine vibration or turbine chamber/rotor stretching.

Project cooperation with operators

The starting point for the design was to involve experienced operators from the plant. During running method meetings, important needs were introduced that Kotkan Energia and Valmet tried to address and have the solutions show up on screens. As an example Roponen mentions group start-ups. "Previously group start-ups could be started, but we did not know what was happening. Now we open various dialog boxes on the desktop and they can be used to start the group. The dialog boxes offer a detailed view of what is going on. We no longer have to guess what has happened."

The project was implemented as team work between Kotkan Energia and Valmet. A temporary testing environment was built in the plant for the purposes of factory testing. During testing, operators got the chance to brainstorm, comment and test the functions and the user interface. The implementation of the automation was carried out during a shutdown as planned. District heat distribution to the city was uninterrupted thanks to distribution by other plants, and process steam was distributed with the auxiliary boiler.

Each operation received operation descriptions in the Valmet DNA system for the use of the operators. The descriptions contain information on e.g., the purpose of the circuit, start-up methods and alarms. According to Roponen, the information is readily available on the screens and does not have to be dug up from folders.

The user interface is up-to-date compared to the old

According to Antti Roponen, Valmet turbine automation brings transparency and availability to turbine operation. With the improved user interface, there is more information available for the purposes of process control and in-depth knowledge on the turbine process.

Operators work in 12-hour shifts of two. One of the operators is Jouni Tenhunen who has nearly 20 years of experience in the field. Jouni Tenhunen says: "The current turbine automation is better than before. The previous system would not specify what caused the fault. We now have access to much more information. If the turbine has a fault we are able to determine the cause immediately."

The turbine protection system has proved useful. Antti Roponen agrees with Tenhunen and says: "The Valmet solution is very informative. When the turbine trips, it is usually followed by a long list of alarms. The current turbine protection logic has a so-called "first in" logic.

It immediately displays the first trigger factor. This function helps with troubleshooting and makes our jobs easier. Thanks to the new controls, the turbine does not have to be run down to turning gear speed, but it is now possible to "catch the turbine on the fly." This enables us to get the generator back online quicker, and district heat production can continue without delays."

One tangible improvement brought with the modernization is connected to the positioning of the turbine power control valves. The old LVDT position sensors were replaced with mA position sensors and the LVDT/I signal conditioners were removed from the distribution casings. Antti Roponen confirms this: "They all now function in the same way, and if a fault occurs, we can utilize the same spare parts."

Antti Roponen from Kotkan Energia and Tom Bäckman from Valmet

Remote service to ensure availability

The starting point for the investment was to ensure the plant’s availability. Roponen says that this has been a success. There are spare parts available for years to come. In addition, Valmet offers Kotkan Energia 24/7 remote support that utilizes the possibilities of industrial internet to streamline the operation of the customer process. Remote support has worked well, albeit there has been little need for it so far.

"The project was a success and the professionals at Valmet did what they promised," Roponen summarises.

More information:

Johan Musch

johan.musch at valmet.com