The Mercure Power plant is located in Calabria region, close to the border with Basilicata.
The plant was originally built in the 60's, with the financial help of the Marshall Plan. The plant was designed to burn Brown Coal, extracted from a coal mine close to the plant. Plant was made of 2 conventional units, 75 MW each, with mixed cooling (cooling tower + river)
After some years, when the mine run out of coal, the plant has been operated with heavy oil, until the 90's, when the production slowely ceased, because of the low profitability of this type of unit.
In order to give a new life to the plant, in the 2003-2005 the plant was converted to burn biomass. Unit 1 was partially domlished, while unit 2 was converted to fluidized bed boiler, boiling type. In that period a lot of activities were carried out, but, unfortunately, the construction was stopped during the commissioning phase.
in 2011 the company decided to restart the plant: since the rebuild of the 2005 the plant has been operated just for few hours.
I was enrolled in the Mercure restart team. After few months, I have been involved in the power system and automation workgroup.
The picture above shows the plant before the 2012 restart activities: the signs of the age are clearly visibile: during the 2005 the conversion team was strongly focused in starting the unit up within the deadlines. All other activities were merely optional.
The rendering shows the ideas for the plant in the final configuration.
Below, some of the exixsting electric panels are shown. Event if the plant was heavly modified in 2005, a lot of activities were left behind, for time / budget reason.
As part of the 2012 reastart team, I struggled to convince the managment to change the old equipments.
The picture above shows the original Ansaldo San Giorgio Medium voltage switchboard. Built in the 60's, the electric protections were upgraded overtime.
A low voltage "power center" type switchgear. Also this was made by Ansaldo San giorgio. The breakers were SACE OTOMAX, with electromagnetic relays.
The picture above shows a 20 kV distribution switchboard. The execution is in bare copper busbars, with gates for the protection against direct contact with live parts. On the right, the protection board, realized with single phase electromagnetic overcurrent relays.
This was probabily the most unsafe situation in the plant, since an arc strike could harm seriously the operator.
The existence of the situations described above worked as a strong leverage for the decision to change the electric equipments. With a mission time of 20 years, the original equipments were a strong issue for the dependability and safety of the plant itself.
On the other side, very strong constraints existed:
- the need to keep up and running the electric system of the plant, because of the construction site being operational
- the need to finish the job within certain time, in order to make it possible the commissing operations
- various layout issues
- an intense promiscuity of old and new cables
In the end the decision was taken: the job was to be done.
In this activity I actively cooperated in:
- preliminary feasibility analysis
- Specification for purchase
- Review of the offers
- Documentation check and engineering support
- Factory acceptance tests
- interface engineering with the automation system
- Erection supervision and temporary power supply strategy
- Startup
Here follow some of the new panels installed.
THe new electric room has a muche neater aspect: brand new floor, new layout and new panels. New interface with automation system
Picture shows a brand new Motor Control Center, that is a form 4B low voltage switchgear, specialized form motor operation, with withdrawable drawers.
This specific MCC features an automatic supply changeover system, featuring a Siemens ATC unit.
Picture shows the new Power center. Main features:
- 2 busbars for duoble radial distribution
- Automatic "Make Before Break" changeover system, developed on MFR (MultiFunction Relays)
- Automatic "Break Before Make" residual voltage changeover system
- 0,4 kV voltage, 50 kA rated short circuit current, 2500 A current rating
New atomation panel, featuring:
- High side cable entrance
- Improved wiring for cleaner installation
- Redundant power supply stage
Brand new Commercial and fiscal metering system, featuring:
- Totally New power meters
- 8 overall power meters
- RS485 interconnection with RTU (remote terminantion unit) and PSTN Modem
- Full Italian Network code compliance
The operation was a success. Further problems where solved, such as:
- Main Transformer restoration
- Generator bay electric protections modification
- Upgrade of the steam turbin speed control, with the installation of an Electro Hydraulic turbine control system
- Generator exciter upgrade, with the removal of the existing coaxial exciter and trhe installation of a new air-cooled static exciter
