Modeling of the Combined Heat and Power System of Greater Copenhagen

The Combined Heat and Power System of Greater Copenhagen, which is a district heating system supplied by CHP plants, is one of the largest of its kind. It is a complex system with different kind of production units, transmission lines and heat storages. Huge costs are related to running the total system, thus effcient planning is needed. Today the daily planning for the system is done by a divided process, where pro- duction companies create production plans, which are then re-optimized by the heat companies taking into account transmission limitations and storages. The re-optimizations are done using a mathematical mixed integer linear program model known as The Katja Model. In the Katja model the production units are included with a fixed production level combined with marginal costs of changing this production level. In this thesis, a much more detailed modeling of the production units of the CHP system is introduced, called The Esben Model. By modifying/extending The Katja Model with The Esben Model, The E&K Model, is derived. This combined model is capable of finding a least cost plan for the entire system in a single process and at the same time represents the production units in a more realistic way than in the original Katja Model. Tests of The E&K Model using real-life datasets are done. In the initial tests it is seen that the complex modeling of a special energy tax makes the solver run out of memory. Thus the modeling of this should be studied further. When running the model without this energy tax a 24 hour plan is found within a minute and as consequence the energy tax are removed from the model in the remaining tests. These remaining tests shows how The E&K Model is capable of representing technical and economical details such as unit commitment, complex production profiles, exibility with respect to electricity prices and costs, multi-fuel boilers, production level dependent fuel effciencies, emissions and the taxes on these and much more. All this shows the many capabilities of the powerful and exible tool which could be used to represent many other CHP systems. In addition to The E&K Model a framework capable of simulating an optimal periodic rescheduling process is presented. A periodical rescheduling process should diminish the uncertainty of the information which the planning is based upon. A test carried out with the framework illustrates that it is important that the quality of the information is increased as time progresses if the periodical rescheduling should have any effect.