WO2000020933A1

WO2000020933A1 - Method for simulating industrial processes

Info

Publication number: WO2000020933A1
Application number: PCT/EP1999/007792
Authority: WO
Inventors: Guido Ceiner; Giuseppe Scafati; Massimo Danieli; Luca Ferrarini; Claudio Maffezzoni
Original assignee: Abb Research Ltd.
Priority date: 1998-10-06
Filing date: 1999-10-05
Publication date: 2000-04-13
Also published as: ITMI982151A1; IT1302615B1

Abstract

A method for simulating an industrial process, characterized in that it comprises the steps of: associating with a generic process portion, implemented in a predefined plant portion, an attribute which is adapted to describe the dynamic behavior of said predefined plant portion; and simulating said plant portion on the basis of said attribute associated therewith.

Description

METHOD FOR SIMULATING INDUSTRIAL PROCESSES

DESCRIPTION

The present invention relates to a method for simulating an industrial process having improved characteristics. It is known that industrial plants in which it is necessary to implement various processes are designed by carrying out a computer simulation of said industrial processes, in order to check the validity of the design before physically building the plant and implementing its processes. It is known that simulators are characterized in that they have a simulation engine conceived to process the equations (and the associated boundary conditions) of all the components of the plant. These components can be, for example, all the physical elements that constitute the plant, such as for example valves, pipes, pumps, compressors and the like. In other words, simulation of a functional block of a plant, composed of a large number of components, occurs by simulating the equations that describe the behavior of the entire set of components.

To summarize, an industrial process is commonly simulated by simulating all its sub-processes and all said sub-processes are in turn simulated by simulating all the individual components (valves, pipes, pumps and the like), each of which has an associated set of equations governing its operation.

However, this approach is characterized by many drawbacks. First of all, the mathematical models of all the components that may be present in a real plant might not be available. Moreover, all the process data required by the various mathematical models, i.e., the parameters of the equations that govern the operation of each component of the plant, might not be available at all or might be unavailable in electronic form.

Moreover, the cost of the simulation, owing to the huge volumes of data to be processed, is excessive with respect to the advantages provided by testing the control system of the plant for which the simulator is normally provided. In fact powerful and expensive computerized means have often to be provided.

The aim of the present invention is to provide a method for simulating an industrial process, which allows simplifying the simulation with respect to known methods.

Within the scope of this aim, an object of the present invention is to provide a method for simulating industrial processes, which allows defining the behavior of complex portions of the process in a simplified manner, in order to make the test of the process control system, economically convenient. Another object of the present invention is to provide a method for simulating industrial processes, which allows reducing the time required for synthesizing the models of the plant to be simulated.

Thus the present invention provides a method for simulating an industrial process, characterized by the fact of comprising the steps of: - associating with a generic process portion, implemented on a predefined plant portion, an attribute which is suitable to describe the dynamic behavior of said predefined plant portion; and

- simulating said plant portion on the basis of said attribute associated therewith. Further characteristics and advantages of the present invention will become apparent from the following detailed description of an embodiment of the method according to the invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein:

Figure 1 is a block diagram of a portion of an industrial plant used to implement the method according to the invention;

Figure 2 is a block diagram, in the form of a tree structure, of a portion of an industrial plant; and

Figure 3 is a block diagram derived from the tree structure of Figure 2, used in the method according to the invention.

With reference to the above figures, the method according to the invention constitutes an innovative approach to the simulation of continuous-control processes whose particularity of the invention lies in the concept of "attribute" which is associated with a generic process portion. Said attribute contains a simplified model of the behavior of that process portion which is formally independent of the behavior of the parts that compose it.

Simulation is accordingly based on the "attribute" of a certain portion of the process implemented on a predefined plant portion, even if this portion is very complicated and highly composite, without having to consider the behavior of all of its subparts.

The attribute, associated with a generic portion of process implemented on a predefined plant portion, which can be more or less complicated, describes the behavior of that predefined plant portion. In general, a plant portion or part is constituted by a certain number of components, which in turn can be composite or elementary. Figure 1 illustrates, by way of example, a plant area constituted by a certain number of motorized valves and pumps and other components. In other words, the plant can be seen as a box, which contains other boxes in turn constituted by a certain number of components.

In Figure 1 , for example, the reference numeral 1 designates a steam turbine, the reference numeral 2 designates a gas turbine, the reference numeral 3 designates a main control unit, the reference numeral 4 designates a boiler, the reference numeral 5 designates supply water, and the reference numeral 6 designates accessory portions of said plant part.

In turn, the block designated by the reference numeral 5 comprises a plurality of motorized valves and pumps and other components.

The attribute of a component, which as mentioned can be a "box" of other components or an elementary component, describes the dynamic behavior of the component.

The attribute therefore summarizes as simply as possible the behavior of a given plant part, making it a single, indivisible object from the point of view of input and output.

In practice, a given plant portion is simulated exclusively on the basis of its attribute, rather than by simulating all its components. For the purposes of the simulation, the attribute allows to eliminate the links among the components, as explained in greater detail hereinafter and as shown in Figures 2 and 3. Figure 2 is a view of an example of a plant portion represented by a tree model which takes into account the relation by which a child node belongs to the parent node.

In particular, the reference numeral 10 designates the plant portion and the reference numeral 11 designates the supply water portion, which has child nodes represented by the pump 12 and by the pump 13.

The plant portion 10 also includes a boiler 14 which has the child nodes constituted by a valve 15 and by a valve 16.

In this manner, with the above-described tree structure, if one wishes to simulate the plant portion 10 one must have an equation of the following type: plant simulation = supply water portion simulation + boiler simulation = simulation of pump 12 + simulation of pump 13 + simulation of valve 15 + simulation of valve 16.

This means that in order to simulate the plant portion 10 it is necessary to have available the dynamic models of the pumps 12 and 13 and of the valves 15 and 16. These might not be available and therefore the simulation might not be impossible.

The concept of "attribute", introduced with the method according to the present invention, instead allows to eliminate the hitherto indispensable dynamic models of the pumps and valves, since the branches of the tree structure, that logically represent the dependent link between the child nodes and the parent nodes, are cut.

Figure 3 illustrates such a concept, in which from the point of view of dynamic behavior each portion of the plant is now an independent object; this behavior is represented by the attribute of said object. In this manner there are no more hierarchical relationships as defined earlier with the tree structure shown in

Figure 2.

In Figure 3, therefore, the reference numerals of Figure 2 are kept for identical elements, but the difference lies in the fact that the arcs that link the child nodes and the parent nodes are no longer present and therefore each block of the diagram is dynamically independent of the others.

The so-called "attribute" describing the behavior of the corresponding component is therefore also associated with each block of Figure 3. Said attribute is designated, for all the blocks, by the reference letter "A".

The concept of attribute determines a simulation approach in which the designer who has to synthesize the attribute of a given object (plant portion) can use an expert system or a library and/or a database but is freed from the need to know in detail the dynamic behavior of the individual components of the object (plant portion).

In this manner it is possible to synthesize in a simple manner the plant model to be simulated, reducing the time and costs required for synthesis and the costs of the hardware devices assigned to the simulation.

The definition of the behavior or attribute of a given plant part is therefore reduced exclusively to a definition of the inputs and outputs of that given plant part, ignoring the presence, in said portion, of components whose behavior to be modeled can even be highly complex.

In practice it has been observed that the method according to the invention fully achieves the intended aim and objects, since it allows to model in a simplified manner an industrial process to be implemented in a plant so as to provide simulated control thereof with reduced times and costs.

The method thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may also be replaced with other technically equivalent elements.

Claims

1. A method for simulating an industrial process, characterized in that it comprises the steps of: associating with a generic process portion, implemented in a predefined plant portion, an attribute which is adapted to describe the dynamic behavior of said predefined plant portion; and simulating said plant portion on the basis of said attribute associated therewith.

2. The method according to claim 1, characterized in that said attribute comprises a simplified model of the behavior of said predefined plant portion.

3. The method according to claim 1 or 2, characterized in that said predefined plant portion comprises a plurality of components.

4. The method according to claim 1 , characterized in that said predefined plant portion comprises a single component.

5. The method according to one or more of the previous claims, characterized in that said attribute is synthesized by means of an expert system.

6. The method according to one or more of the previous claims, characterized in that said attribute is synthesized by means of a library and/or a database.

7. A method for designing control systems for industrial plants characterized by the fact of using a method for simulating an industrial process according to one or more of the previous claims.