Process control engineering in the virtual environment for a modern waste incineration power plant
250.000 alarms, more than 10.000 process objects, 54 monitors. How can you combine such quantity structures using a single process control system, including 700 external control units as well as components of various manufacturers? The waste incineration power plant in Wuppertal realized such a line upgrading – highly available and during operation.
Five incineration lines, four exhaust gas pre-cleaners, three exhaust gas post-cleaners and two turbines for a waste tonnage of around 400,000 tons per year - AWG Abfallwirtschaftsgesellschaft Wuppertal operates a waste incineration power plant for the thermal treatment of waste. The process control engineering, which had been discontinued by the previous supplier, was to be modernized in two stages. The availability of the overall system was important for two reasons: The failure to comply with the contracts with the municipalities leads to heavy penalties, and furthermore, many consumers depend on district heating. In the worst case, a system failure is associated with an uncontrolled escape of flue gases and thus poses a risk to the environment and health.
The new system was first tested 100 percent in parallel operation, after which half of the operator panels of the legacy system were replaced with the new Simatic PCS 7 OS stations. During a four-week test phase, intensive system testing and operator training took place. Thereafter, the legacy system was shut down and the new PCS-7 control system was put into operation.
400 process images were transferred to the new system. More than 10,000 process objects were transferred into 35 basic types with about 250 different derivatives (views). WinCC/ODK (Open Development Kit) could be used to convert all process pictures of the previous process control system and to integrate them in the new system. Since then, about 70,000 process variables have been exchanged via the operating and monitoring system.
A special focus was turned on the high system availability. This is ensured, among other things, by the redundant design of all hardware components such as servers, storages, network infrastructure, time servers and uninterruptible power supplies. Additional security is provided by the spatial separation of the redundant system. The use of a virtual cluster ensures the availability of the operating systems. Both servers are designed in such a way that, in the event of a fault, one server alone can take over the entire system. This is made possible by the use of a redundant storage cluster.
The system from Siemens unifies different forms of operation and visualization as well as their alert systems. Machine-related controls from different manufacturers can be seamlessly integrated into the process control technology and thus into a uniform operating and monitoring system with Open OS. Monitoring of all process objects, from initial ignition in the burners, power generation in the turbine and generator, to emission monitoring in the flue gas system, is handled by the Siemens operating and monitoring system. Each operator monitors up to twelve screens simultaneously. Thanks to the clear display, which is based on the legacy system, the plant operator has all the important information at a glance. New systems and components can be integrated at any time during ongoing operation, regardless of manufacturer.
Stage 2, the modernization of the complete automation technology with AS 410 controllers from Simatic PCS 7, is to be completed within the next five to ten years. A high-availability AS 410 is already in use for initial tests. The installation of another redundant Simatic PCS 7 server pair has already taken place last year. While the field level is still classically wired today, in the future AWG will also rely more on bus communication and thus Profinet/Profibus. The project planners already agree that the decentralized peripheral ET 200 will be used for this purpose.