Communication via optical fibers
Connection to field devices is ensured through 27 S800 remote I/Os. Besides the controller architecture, the entire communication with the remote I/Os via optical fibers is redundant. The three operator stations and the engineering station also communicate via a redundant network structure. They have a total of ten monitors and two large screens. A Profibus connection, which is also redundant, connects the HIMA safety system for burner safety and boiler protection to System 800xA.
The service provided by ABB engineering partner Stadler + Schaaf includes creation of the specifications, detailed engineering as well as the installation and wiring of the entire electronics and automation engineering. Other than the control system, this includes all the instrumentation and the integration of numerous subordinate PLCs via OPC. Stadler + Schaaf also installed the low-voltage and medium-voltage systems. The automation experts from Offenbach an der Queich manufactured and delivered 130 switch cabinets. Following the loop check and commissioning, the first steam was fed into the power plant in July 2013.
“The main challenges included the unit control system, including the tertiary reserves, taking account of the process steam supply and district heating,” explains Peter Schandin, project manager at Stadler + Schaaf. “The coordination and system-neutral integration of the third-party units and black boxes into the process control system were also technically and organizationally challenging,” Schandin continues.
Monitoring other plant sectors
In the medium-voltage range, Stadler + Schaaf set up three ACS800 frequency converters for the forced draft fan, the induced draft fan and the feed water pump. A further 42 ABB ACS850 and ACS350 frequency converters were installed in the low-frequency range. Around 2,700 I&C signals, predominantly from ABB temperature and pressure measurement devices, and a further 650 signals from the electrical fittings of the power plant come together in the control system. Furthermore there are more than 14,000 signals from the PLCs, which are transmitted via OPC. These monitor and coordinate other parts of the power plant, such as screw synchronization, the turbine, the process steam and heat extraction or the flue gas cleaning.