The project which is funded by the German Federal Ministry of Economics and Technology was sub-contracted to the Institute of Energy Systems by Vattenfall Europe Wärme AG (Hamburg). Other project partners are Vattenfall Research and Development AB (Branch Office Germany), Evonik Energy Services GmbH (System Technologies Division) and the engineering bureau for district heating technology Dr. Klöpsch.

Maintenance planning in CHP plants today is still based mainly on empirical values from preventive maintenance strategies. The disadvantage of this approach is that maintenance may be performed either too early or too late, which leads to increased operating and maintenance costs. An alternative approach is based on the concept of condition-based maintenance. To use this strategy the actual condition of a component has to be monitored accurately. Online power plant simulation can be an appropriate method to deliver objective decision criteria for condition-based maintenance planning. Through plant modelling operational process data will be used for calculating the Key Performance Indicators (KPI). In this manner it will be possible to determine the influence of the actual condition of the component on its actual performance. On the basis of the trends in these key performance indicators it is possible to determine proper decision criteria and define the best maintenance date. In addition, online performance monitoring of CHP plant components can reveal vulnerabilities in process design or help detect component failures. Hence a further benefit expected out of the project is a means to increase the energy utilization index and the plant availability.

The main contribution of the Institute of Energy Systems comprises the identification of appropriate key performance indicators which during operation reflect the deterioration of the condition of the whole plant or of key components. In the first instance potential key performance indicators will be tested and evaluated using historic operational data from the Wedel CHP unit 1 (operated by Vattenfall Europe Wärme AG). Promising key performance indicators will then be implemented to perform online tests under normal plant operation. The findings and results will be incorporated afterwards in an algorithm for optimizing maintenance planning of CHP plants.