Case Study Local Energies – Cost-efficient system for trouble-free operation of paint-spray line
Local Energies, a.s. is a daughter company of the E.ON Czech grid company in the Czech Republic. The main business area is the operation of energy networks for industrial customers and providing solutions in the energy networks area, such as voltage stabilization, ancillary services and energy storage solutions. Local Energies acts as distributor of U-UPS systems for the Czech Republic and Slovakia – as for its client ŠKO-ENERGO s.r.o. Since its foundation in 1995, ŠKO-ENERGO s.r.o. has been supplying plants of ŠKODA AUTO a.s. in the Czech Republic with electricity, water, heat and gas, as well as private households, companies and facilities in the city of Mladá Boleslav with district heating. In addition, the company is also responsible for the operation and maintenance of the car manufacturer‘s energy systems. Around 350 employees currently work for the company.
Initial situation and challenge
As a result of up to 50 voltage dips in the power transmission network per year, the fully automated painting line for chassis regularly came to a standstill in the production plants of the Czech car manufacturer. The robots shut down at interruptions of 0.2 seconds or more, bringing painting operations to an abrupt halt. The economic damage caused by the production downtime of up to 6 hours, the resumption of the robot activity and for the repair of the damaged vehicle parts was considerable.
Scope of Delivery
FREQCON GmbH received an order from Local Energies in 2018 to design and commission a turnkey container solution consisting of a multi-source converter and ultracapacitor storage with a capacity of 1 megawatt for voltage dips of up to 1.5 seconds for the Czech car manufacturer‘s production site in Mladá Boleslav. At another site – in Kvasiny – one more plant was built in 2019, with a capacity of 500 kilowatts to bridge voltage dips of up to 2 seconds. These systems are owned and operated as a service by Local Energies for the end customer ŠKO-ENERGO.
Local Energies was in discussion with various manufacturers of systems for an uninterruptible power supply and ultimately decided for the most economical solution – the FREQCON U-UPS. The ultracapacitors of this system are charged by the public grid during normal operation. U-UPS automatically responds to voltage dips as well as micro-interruptions and takes over load supply in less than 10 milliseconds. The integrated FREQCON Fast Disconnector separates the power supply from the public grid and the U-UPS generates its own isolated grid using the energy stored in the ultracapacitors. This island network uses the same nominal voltage, phase angle and frequency as the public network. As soon as the transmission grid makes the appropriate voltage available again, the system synchronizes with the public grid within a few milliseconds and re-establishes the connection to it.
Since implementation of FREQCON‘s U-UPS solution, none of the short voltage dips in the transmission grid resulted in production interruptions. Throughout the bridging process, the system ensures consistent power quality and performance, so there are no error messages or downtimes for the sensitive robots on the paint line. In view of the previously incurred downtime and repair costs, the investment in the U-UPS system paid for itself within just a few months. In addition, the system is cost-efficient regarding operation, service and maintenance