EBSILON®Professional Online Documentation
Power plants can be classified based on different criteria:
Based on fuels, such as nuclear, conventional with the fuels bituminous coal, lignite, oil, gas, additional fuels as bio-gas, waste, water, wind etc. Alternatively, they can be classified on products, such as power, district heat, process steam, or on size, such as >800 MW, 100-800 MW, 10-100 MW, < 10 MW, according to the year of erection and, therefore, steam conditions, on national standards and local conditions, on fluid types or on operation, such as basic load or peak load. The classification on these criteria gives a guideline for the topology, type of the components and parameters of components. For modeling, such criteria can be used to generate model power plants, on the basis of which the power plant in question can be modified and adjusted. In addition, it is also possible to make a database of the default values. This saves time when setting the parameters during modeling and leads to a faster engineering of a project. It also enables the manufacturers of the components to set the parameters reliably for the areas, for which the know-how is low.
The life cycle of the energy plants comprises of different phases, which include planning, construction, operation and dismantling. These main phases include a series of sub-processes, such as project planning, engineering, purchase, manufacturing, transportation, assembling and commissioning, production, maintenance, inspection, etc.
These sequential looking process are closed by several, often called as experience back-flow loops for technical information. Thereby, the back flow from the operating data i.e. the output of the process chain during commissioning, trial run, acceptance tests and production operation is especially important.
The general aim of a modeling of a virtual power plant is to improve the different business process phases by power plant modeling. Because the different phases in most cases involve different companies having different core activities, there are different aims depending upon the company. It is even possible that these objectives change with time. For instance, reliability of the power plant was the main aim for a long time; today, the product price is the main goal.
Elements of modeling in the software system EBSILON®Professional are, on one hand, the components, which model the thermodynamic and process-technical components, such as turbines, heat-exchangers, pumps, etc. On the other hand are the control elements, which are primarily used for control mechanisms, such as controllers or calculators.
For components and control elements the specification values can be set internally or externally. The behaviour can be controlled by activating different modes.
A component serves for the virtual determination of specific output parameters, when the input parameters are specified. The behaviour is described by thermodynamic laws or by characteristic lines.
The behaviour is specified for all components. The component "Programmable Component" enables the free, customer-specific programming of any component.
Control elements enable you to model control structures, calculation links and value transfers between the pipes. With their help, it is possible to build logical connections or to implement target value specifications.
In the topology, the arrangement of components and control elements is done, so that the plant to be modelled can be calculated as per the objectives set.
The degree of detailing of the topology determines the effort involved for modeling and model customization on one hand, and the model benefits on the other. In case of planning applications, the optimum is reached, when the modeling is so detailed that the scope of supply and services, characterized by guarantees, can be fulfilled with a minimum effort without later improvements.
The parameters are set via the input screens of the components and control elements or via the input of start or boundary values. The main system of units is selected, which fits in the settings, so that the data can be entered without any conversions. However, the system of units need not be uniform in a model.
The default values can be managed in libraries. Thereby, it is possible to classify the libraries in classes of component default parameters, fuel libraries, etc.
The measured values are entered via the control elements, which can be positioned freely on the pipelines. In case of power plant applications, it is better to use the power plant nomenclature AKZ/KKS.
The programming environment EbsScript provides a tool for automating the model calculations and also for extending the component applications. Each variable of each component can be accessed and also manipulated. While modeling the power plant, this is especially relevant for the so-called What-If- calculations, in which virtual states can be compared with one another.
Loops are possible for iterations, with whose help target values can be found.
Another possible application is the consideration of geometric data. In EbsScript the component parameters can be calculated by taking into account the geometry, with which the simulation calculation can then be carried out.
Basically, only that much calculation should be made available in the model that is possible.
Component connections must be selected with respect to the fluid before connecting them with pipes. It is not possible to change the medium, if a pipe is connected.
When using the controllers, it is helpful to deactivate the controller first and to ensure that the model executes, and then to activate the controller.
The model may not have any contradictory statements regarding the pressures. This must especially be noted when specifying pressures for components, which themselves possess pressures as specification values. In each case it must be defined, whether the specification values or else the values given from outside are used for a component. The changeover is done in the respective component specification.