WO2010121667A1

WO2010121667A1 - Improved overview of process control data on an operator terminal display of a process control system

Info

Publication number: WO2010121667A1
Application number: PCT/EP2009/057966
Authority: WO
Inventors: Mikko Rissanen
Original assignee: Abb Research Ltd
Priority date: 2009-04-21
Filing date: 2009-06-25
Publication date: 2010-10-28

Abstract

The present invention relates to a method of allowing a user to get an improved overview of process control data values on an operator terminal display, an operator terminal in a process control system as well as to a computer program product for such an operator terminal. The method includes the steps receiving (38) a user selection of process control data values being presented on the display, fetching (42) the selected process control data values, forming (44) at least two groups of process control data values, where a first group only includes process control data values of a first type and a second group only includes process control data values of a second type, and graphically presenting (50) the process control data values in the two groups separated from each other in order to improve the overview of the process control data.

Description

IMPROVED OVERVIEW OF PROCESS CONTROL DATA ON AN OPERATOR TERMINAL DISPLAY OF A PROCESS CONTROL SYSTEM

FIELD OF THE INVENTION

The present invention generally relates to operator terminals in process control systems. More particularly the present invention relates to a method of allowing a user to get an improved overview of process control data values on an operator terminal display, an operator terminal in a process control system as well as to a computer program product for such an operator terminal .

BACKGROUND

Operators have the need to monitor and visually compare a chosen number of different process control data values that are provided by process interface units to a process control system, where the process control system visualizes the process control data values in different views and windows. The process control system can be a SCADA (Supervisory Control And Data Acquisition) system and in particular a power grid control system.

Normally power grid or other SCADA systems' operators have to search values in multiple "pages" or views of the process control system before they are able to compare and monitor the values. In a normal case, realtime values are compared either to historical values of the same source, e.g. an electrical device, or to other real-time values of a different source. Typically, historical values are shown separately from the realtime values, because different systems are used for these two kinds of data. When the operator has found the values he or she wants to compare and monitor, the operator has to keep many pages or views open, which in some cases even may be displayed on multiple screens or display devices, in order to see just a few interesting values in each.

EP 0875826 describes a monitor control system which comprises an information gathering section for gathering information about a state of a system which is to be monitored and controlled. Here, there are provided screen images of information relating to the state of the to-be-monitored and controlled system. These screen images can be displayed. However, the document is silent regarding how data is grouped and displayed.

There exist different ways of visualizing data.

CA 2305538 does for instance describe an interactive system for visualizing business data organized according to a specific model called the dimensional model. According to this document data from more than one source are selected and presented together in the form of graphical multimetric data visualization.

US 2008/0275690 describes a simplification of the visualization of a selection of data. Here, software on a computer system is configured to use a set of rules to select some of all the data items occurring in the function model automatically as the data items to be visualized.

US 2006/0114963 describes a system and a method for monitoring the operating parameters of an electric arc furnace. Here, data is collected and transmitted to a monitor in substantially real-time. It is here also possible to manually add data to the monitoring system viewer .

US 7197719 shows a method for selecting parameters and then display the selected information.

In view of what has been described above there exist different solutions for visualizing data that have been selected by a user. However, there is in this regard room for improvement, especially with regard to user- friendliness .

SUMMARY OF THE INVENTION

The present invention addresses this situation. The invention is thus directed towards solving the problem of improving user friendliness in relation to presentation of process control data on an operator terminal of a process control system.

Accordingly, the present invention is based on the realization that there is a need for a better visualization of user or operator selected process control data values which are not only to be monitored in some way but which have to be visually compared with each other. The present invention is therefore directed towards solving the problem of providing a better and more user-friendly visualization of user selected process control data values which are to be monitored and visually compared by the user.

This problem is according to a first aspect of the invention solved through a method of allowing a user to get an improved overview of process control data values on an operator terminal display in a process control system, where at least two of the process control data values are of the same type, comprising the steps of: receiving, in the operator terminal, a user selection of a number of process control data values being presented on the display, fetching, by the operator terminal, the selected process control data values, forming at least two groups of process control data values, where a first group only includes process control data values of a first type and a second group only includes process control data values of a second type, and graphically presenting on the operator terminal display the process control data values in the at least two groups, where the at least two groups are presented separated from each other in order to improve the overview of the process control data.

This problem is according to a second aspect of the invention solved through an operator terminal in a process control system including a display, a user input unit and a control unit, the control unit being configured to receive a user selection of a number of process control data values being presented on the display, - fetch the selected process control data values, form at least two groups of process control data values, where a first group only includes process control data values of a first type and a second group only includes process control data values of a second type, and graphically present on the display the process control data values in the at least two groups, where the at least two groups are presented separated from each other in order to improve the overview of the process control data.

This problem is according to a third aspect of the invention solved through a computer program product on a data carrier comprising computer program code configured to cause the operator terminal to, when the computer program code is loaded into an operator terminal provided in a process control system, receive a user selection of a number of process control data values being presented on a display, fetch the selected process control data values, form at least two groups of process control data values, where a first group only includes process control data values of a first type and a second group only includes process control data values of a second type, and graphically present on the display the process control data values in the at least two groups, where the at least two groups are presented separated from each other in order to improve the overview of the process control data.

The invention eliminates the need of showing all the views or pages that contain the interesting real-time information by letting the user select the areas or values of interest within the different graphical views which the process control system displays on an operator terminal. The selection can be performed with a simple gesture using a pointing device, e.g. a mouse, thus making the overall comparison and monitoring faster for the operator to perform. The required space on the display of the operator terminal is therefore reduced. Grouping into various views that are of relevance to the user is furthermore done automatically without the user having to perform multiple selections and actions. In this way the invention facilitates to the user the task of comparing data with each other.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will in the following be described with reference being made to the accompanying drawings, where

Fig. 1 schematically shows a computerized process control system,

Fig. 2 schematically shows an operator terminal of the present invention, Fig. 3A schematically shows a first single-line diagram presented on an operator terminal in a power transmission system of the present invention, Fig. 3B schematically shows an alarm list presented on the operator terminal,

Fig. 3C schematically shows a second single-line diagram presented on the operator terminal, Fig. 3D schematically shows a system overview presented on the operator terminal,

Fig. 3E schematically shows a detail of the first single-line diagram presented on the operator terminal,

Fig. 4 schematically shows two interactive monitoring spaces presented on the display of the operator terminal, and fig. 5 schematically shows a flow chart of a number of method steps being performed in a method according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following, embodiments of the invention providing the above described functionality will be described.

Fig. 1 schematically shows a computerized process control system 10. The process control system 10 may typically be an object based computerised system for controlling a process or perhaps part of a process. Typical processes are for example electrical power generation, transmission and/or distribution processes, water purification and/or distribution processes, oil and/or gas production and distribution processes, petrochemical, chemical, pharmaceutical and food processing processes, as well as pulp and paper production processes. These are just some examples of processes where the process control system 10 can be applied to. There exist countless other processes. The process may be monitored and control by a user or operator through an operator terminal, which communicates with a control server handling monitoring and control of the process. One preferred field where the present invention is to be applied is a power transmission system.

In fig. 1 the process control system 10 therefore includes a number of operator and engineering terminals 12 and 14 connected to a first bus Bl. There is furthermore a second bus B2 and between the first and second busses there are connected a first server 16 providing control of the process, a second server 17 providing monitoring of the process and a database 18 where data relating to control and possibly monitoring of the process is stored. Such data is here also called process control data. To the second bus there are furthermore connected process interface units for providing control and measurements in the system 10. The first server 16 is therefore a part of a control system, while the second server 17 is a part of a monitoring system. In the figure 1, there are provided four such process interface units 20, 22, 24 and 26 connected to a power line 28. It should here be realized that some of these may only be provided for control, some only for measurements and some for both control and measurements. Such process interface units are thus involved in controlling the electrical power transmission process or measuring properties of the controlled process as well as properties or status of control and measurement units. Process interface units can include elements directed towards measuring such as current, voltage and power measurement units like current transformers and voltage transformers, as well as elements directed towards control operation like circuit breakers, relays, power semiconductor switches and tap changers. It can also be a higher level element like a generator or even a whole control station. These are just a few of several different possible types of elements that can be provided in process interface units .

The first server 16 here receives measurements of the process via the process interface units and controls the process via the process interface units based on these measurements. It also stores historical process control data in the data base 18. The second server 17 receives measurements via the process interface units as well as status data concerning the operation of process interface units and can generate alarm and event data that may be presented via the operator terminals 12 and 14. It can also shut down the process. Also alarm and event data may be stored in the database 18.

In the example of figure 1, a so called Network Manager system runs on the process control system 10, which belongs to the group of SCADA (Supervisory Control And Data Acquisition) systems. The Network Manager system is particularly intended for the supervision and control of power transmission systems or gas systems.

An operator terminal 12 and 14 in the process control system 10 provide each a user interface to the Network Manager system. In the following, the details of such an operator terminal are explained based on the example of operator terminal 12, shown in figure 2. The operator terminal 12 includes a user input unit 32, a display 34, a control unit 30 and an interface 36 for communicating with the system 10 via the first bus Bl. As said above, the operator terminal provides a graphical user interface for an operator of the process control system 10. The control unit 30 may be a processor with an associated program memory including program code for performing the functionality of the present invention, which will be described later on. The user input unit 32 is a unit through which a user of the operator terminal 12 may enter data. As such it may be a keyboard, a keypad or a pointing device like a mouse. A combination of these may be also be used. It may also be combined with the display 34 in order to form a touch screen. The operator terminal 12 may also include other user interfaces such as a speaker or a microphone in order to present and receive data to and from one or more users of the operator terminal in other ways than through the display and keyboard. An operator terminal in a process control system is only one example of a computer in which the present invention may be realized.

Process control data values from the various process interface units can be collected and stored in the history data base 18 by the first server 16 as well as presented in real-time to an operator via the operator terminal display 34.

On the operator terminals 12 and 14 there are shown graphical symbols of the controlled process and process interface units or parts of such process interface units. Thus graphical symbols are shown which may represent process interface units or parts of them as well as parts of the power transmission system, such as power generation plants, power transmission and distribution lines, power transmission control stations, in particular substations, or subparts of all these parts. These graphical symbols thus represent system elements and are furthermore with advantage shown as being interconnected in a control structure used for controlling the process, which structure can be shown in a single line diagram. On the display there may also be shown process control data associated with these various elements. One such representation of the control structure of a part of the power transmission system is shown in the fig. 3A, which shows a first screen SCRl displaying a first single-line diagram where a substation called Amherst is visualized together with a large amount of measurement and status data.

The first server 16 continuously obtains real time measurement data. As new measurement data is obtained, old measurement data is stored as historical data in the historical data base 18. The graphical user interface of operator terminals 12 or 14 supports the operator to control the system 10, and here in particular the substation shown in the first screen SCRl in figure 3A. Therefore, the operator needs a good representation of the information including such real time measurement data as well s historical datato make the right decisions. One problem is that the information is scattered to different places and views of the graphical representation of the power transmission system and it is hard for the operator to see patterns and outliers in the information, where outliers means values which lie outside the normal value range.

The invention eliminates the need of showing all the pages or views that contain the interesting real-time information, i.e. the real-time information which the operator wants to monitor and in particular to visually compare with each other. This is achieved by letting the operator select values of interest or whole graphical areas containing values of interest within the different graphical views or pages which the process control system 10 displays on the operator terminal 12. The selection can be performed with a simple gesture using a pointing device, e.g. a mouse. The invention allows the control unit 30 to automatically deduce what values have been selected on the pages and to extract the corresponding information from both real-time and history data, i.e. both from the first server 16 and the data base 18. The control unit 30 in the operator terminal 12 deduces values that are coming from the same or similar process interface units or sources and groups similar values together so that information can be compared visually without having any other, momentarily irrelevant, information visible. In other words, the values to be compared and monitored become a single entity that can be shown as one logical comparison page or in one viewable operator area, which is updated in real-time if real-time values have been selected. Moreover, values that have been selected after the first selection was made can be added into the comparison page. The updated comparison page may then be presented in a so called Interactive Monitoring Space, where it is shown together with the previous values of similar types and/or sources.

A first embodiment of the invention will now be described with reference being made to the previously mentioned fig. 1, 2 and 3A as well as with reference being made to fig. 3B, which schematically shows a second screen SCR2 displaying an alarm list presented on the operator terminal, to fig. 3C, which schematically shows a third screen SCR3 displaying a second single-line diagram presented on the operator terminal, to fig. 3D, which schematically shows a fourth screen SCR4 displaying a system overview presented on the operator terminal, to fig. 3E, which schematically shows a detail of the first single-line diagram, to fig. 4, which schematically shows an interactive monitoring space presented on the display of the operator terminal together with the first, second, third and fourth screens, and to fig. 5, which schematically shows a flow chart of a number of method steps being performed in a method according to the invention.

The example below is based on a graphical representation generated by ABBs Network Manager, which is a process control system especially suitable for electrical power generation and transmission as well as for gas transmission systems. In this scenario, the operator wants to compare and monitor real-time and historical values of two generators Gl and G2, i.e. of two similar parts, of a power station or substation called Amherst. Fig. 3A shows a view of a first single line diagram (SLD) of this station together with a large amount of measurement and status data. The user here makes a selection Sl of data values in this single line diagram.

The method according to the first embodiment of the invention therefore starts with the user or operator selecting data to be presented on the display. The selection is furthermore made in relation to a number of views or screens presented on the display 34 of the operator terminal 12. It should here be realized that many of these views or screens may be presented simultaneously on the display 34. It is for instance possible that the screens SCRl, SCR2, SCR3 and SCR4 shown in fig. 3A - D are all shown simultaneously, where the first screen SCRl in fig. 3A may occupy for instance the upper half of the display, while the screens SCR2, SCR3 and SCR4 in fig. 3B - D in that case would occupy the other lower half.

The user thus selects data in the single line diagram, which selection Sl is shown in more detail in fig. 3E . Selection may be performed using a standard 2-button mouse .

The operator may for instance press and hold the left mouse button and drag the mouse from top left in a direction towards bottom right within each of the views shown in Fig. 3A, 3B, 3C and 3D. A virtual area is then created within each view. This area may be a rectangle. However it may also be a circle or an ellipse. The virtual areas which are thereby drawn results in a selection of the process control data values which are graphically located within each such virtual area. By doing that, the operator selects in this example in the first view in fig. 3A, four values on each generator Gl and G2, resulting in a total of 8 selected values GlP, GlQ, GlS, GlU, G2P, G2Q, G2S and G2U. The values GlP and G2P are here measurement values of a first type, the values GlQ and G2Q are measurement values of a second type, the values GlS and G2S are measurement values of a third type and finally the values GlQ and G2Q are measurement values of a fourth type. The selection Sl or virtual rectangle of the first view is shown with a higher zoom level in Fig. 3E . The selected values in this example relate to the power factor of the two generators Gl and G2. Here P denotes real power measured as MW, Q denotes reactive power measured as MVAR, S denotes apparent power measured as VA, and U denotes generating voltage measured as kV. In the second view, shown in Fig. 3B, a list is shown, which is an alarm list. This list is here a list of alarms in the substation Amherst of the single line diagram in fig. 3A. Here the operator selects S2 one value in the list. In fig. 3C a second single-line diagram is shown. This single line diagram may be a diagram of an element from the first single line diagram. As an example the operator here selects S3 one other value. In the map view, which is an overview of the whole system that can be seen in Fig. 3D, the operator selects S4 two values.

As the user has made the selection Sl via the user input unit 32, the selection Sl is transferred to the control unit 30 of the operator terminal 12. This means that the control unit 30 of the operator terminal 12 receives the user selection Sl of a number of process control data values being presented on the display 34, step 38.

The control unit 30 detects which area of the screen became selected and which values are within the selection bounds. The control unit 30 therefore automatically retrieves the selected process control data values. In this example it furthermore retrieves from the corresponding process interface units the real-time data belonging to the selected process control data values, i.e. the actual measurement or status information which relate to the selected process control data values. The control unit 30 thus fetches process control data for the selected process control data values, step 42. In addition, the control unit 30 may in a specific solution automatically retrieve from the data base 18 the historical data belonging to the selected process control data values. Thereafter the types of the process control data values are determined. Here it is also possible that also the types of sources are detected, where the sources are the corresponding process interface units providing the measurement or status information relating to the selected process control data values. Thereafter similar process control data values are logically grouped together by control unit 30 using a set of similarity rules. One similarity rule may be source type, i.e. different process interface units providing process control data values. A transformer may here be one source type, while a generator may be another source type. Another similarity rule may be data value type, e.g. different kinds of parameters measured in a power generator. In relation to data values it is furthermore possible to apply a similarity criterion. These similarity rules and the similarity criterion are then used by the control unit 30 in forming a number of groups in which the retrieved process control data is then placed.

The control unit 30 thus forms groups with process control data at least according to type of process control data, step 44. Here it furthermore forms at least two groups GRl and GR2, where the first group GRl only includes process control data values of a first type and the second group GR2 only includes process control data values of a second type. Additionally the control unit 30 may also base the forming of groups on source type, which means that if the first and second type of process control data could also be generated by two different sources, then at least four groups could be formed.

After having formed these groups the control unit 30 according to the first embodiment continues and investigates if data values of at least one type fulfill the similarity criterion, step 46. The similarity criterion investigation may here be performed per group. It is furthermore possible that it is just performed for some groups. This investigation is made in order to find out if the process control values in a group are similar to each other, within system requirements or if they are deviating in any way. If the similarity criterion is not fulfilled, in such an investigation, step 46, a further group including some of the investigated process control values is created, step 48. Process control values that fulfill the similarity criterion may be placed in one of said at least two groups and data values that do not fulfill the similarity criterion are placed in the further group. The similarity criterion may be set as a difference level between the data values of a type, where data values of this type are placed in different groups based on if this difference level is reached or not. The similarity criterion could also be set as a threshold that each value of the investigated type is compared with and data values are placed in different groups based on if they cross this threshold or not, such as if they exceed it.

In the first embodiment of the invention the similarity criterion is set as a difference level. Grouping of process control data is furthermore done based on both process interface unit type and process control data type.

In this first embodiment the similarity criterion is as an example a measurement-specific difference limit such as a maximum 10% difference between the values of the same type generated by two different process interface units of the same type, (which can be computed automatically from the process data' s abnormal value thresholds) .

In the present example G indicates generator. This means that the measurement values G1P=35O.OMW and G2P=361.6MW are similar by source type and value type so they form a first group GRl, since the sources are both generators and the value types are both of the type real power. In a similar manner G1S=355.1MVA and G2S=116.0MVA have similar source type and similar value type so they form a second group GR2, since the sources are both generators and the value types are both of the type reactive power. However, as G2S's value (116. OMVA) exceeds the difference limit when compared to GlS' s value (355. IMVA), it is separated to be the single measurement in a further group, GR3. Now, Gl contains GlP and G2P, while the second group GR2 includes GlS. This re-grouping allows the operator to directly see relations between similar values without being limited to technically straight-forward comparison of the parameters' source type only.

GlQ=-36.9MVAR and G2Q=-36.0 MVAR are also similar by source type and process control data value type so they become another group GR4. The difference between these values does not exceed the limit, so they remain in the same group. GlU=16.2kV and G2U=16.2kV belong to a fifth group GR5 as they have the same source type as well as type value . Further groups may then be formed according to these principles.

After these groups have been formed, both when the similarity criterion is fulfilled and when it is not, the control unit 30 continues and graphically presents the process control data values in the different groups on the operator terminal display 34. The groups are here furthermore presented separated from each other in an interactive monitoring spaces IMS, step 50. Presenting may here be through showing curves or trends of the process control data in this space. A graphical representation of the real-time data and optionally of the historical data as well, is thus generated for each of the groups. The graphical representation thus becomes visible, under the control of the control unit 30, to the operator in an interactive monitoring space, IMS. This interactive monitoring space may then be presented together with one or more of the first, second, third and fourth screens SCRl, SCR2, SCR3 and SCR4. In fig. 4 the interactive monitoring space IMS is shown together with all four screens.

After this has been done, the control unit 30 then returns and awaits further user selections, step 38, for instance the selection S2 and thereafter presents, step 50, data of this selection in the interactive monitoring space. This may be followed by the user selection S3 and data of this selection is then presented in the interactive monitoring space. This selection may be followed by the selection S4 and data of this selection is then presented in the interactive monitoring space.

The present invention may be varied in many ways. It is possible with other types of similarity criterion investigations than the ones described above. It is for instance possible with an adaptive similarity criterion being set by the control unit for a group based on the number of measurement values, process interface unit types and already formed groups. However, these investigations can also be omitted completely. It is also possible that grouping according to process interface unit type is not made.

The power transmission system in fig. 1 is simplified in that it is limited to one process control system 10 and one power line 28. A system can include several control stations or systems and several power lines. In this case it is possible that control and protection computers as well as operator terminals exist on a higher hierarchical level, a system level, in which the invention may also be provided.

The operator terminal may, as was previously described, preferably be provided in the form of one or more processors together with computer program memory including computer program code for performing the present invention. This computer program code may also be provided on one or more data carriers which performs the functionality of the present invention when the program code thereon is being loaded in an operator terminal .

Claims

1. Method of allowing a user to get an improved overview of process control data values on an operator terminal display (34) in a process control system (10), where at least two of the process control data values are of the same type, comprising the steps of: receiving (38), in the operator terminal (12), a user selection (Sl, S2, S3, S4) of a number of process control data values being presented on the display, fetching (42), by the operator terminal, said selected process control data values, - forming (44) at least two groups (GRl, GR2) of process control data values, where a first group

(GRl) only includes process control data values of a first type and a second group (GR2) only includes process control data values of a second type, and graphically presenting (50) on the operator terminal display said process control data values in said at least two groups, where the at least two groups are presented separated from each other in order to improve the overview of the process control data.

2. Method according to claim 1, wherein the data values are linked to corresponding process interface units (Gl, G2) and a first group furthermore only includes data values associated with a first type of process interface unit.

3. Method according to claim 1 or 2, further comprising the step of investigating (46) if data values of at least one type fulfill a similarity criterion or not and forming (48), if said similarity criterion is not fulfilled, a further group including some of the investigated process control values of said type.

4. Method according to claim 3, wherein data values that fulfill the similarity criterion are placed in one of said at least two groups and data values that do not fulfill the similarity criterion are placed in said further group.

5. Method according to claim 3 or 4, wherein the similarity criterion is set as a difference level between the data values of said type, where data values of said type are placed in different groups based on if this difference level is reached or not.

6. Method according to claim 3 or 4, wherein the similarity criterion is set as a threshold that each value of the type is compared with and data values are placed in different groups based on if they cross said threshold or not.

7. Method according to any of claims 3 - 6, further comprising the step of adaptively setting the similarity criterion of a group based on the number of measurement values, process interface unit types and already formed groups.

8. Method according to any previous claim, wherein process control data values in at least one group include both real-time measured and historical process control data values.

9. Method according to any previous claim, wherein each group of process control data values is being presented in a separate interactive monitoring space (IMS) on the display.

10. Method according to any previous claim, wherein the step of fetching includes fetching process control data values from all entities in the system where they are stored.

11. Operator terminal (12) in a process control system (10) including a display (34), a user input unit (32) and a control unit (30), said control unit being configured to receive a user selection (Sl, S2, S3, S4) of a number of process control data values being presented on the display, fetch said selected process control data values, - form at least two groups (GRl, GR2) of process control data values, where a first group (GRl) only includes process control data values of a first type and a second group (GR2) only includes process control data values of a second type, and - graphically present on the display (34) said process control data values in said at least two groups, where the at least two groups are presented separated from each other in order to improve the overview of the process control data.

12. Operator terminal according to claim 11, wherein the data values are linked to corresponding process interface units (Gl, G2) and where a first group furthermore only includes data values associated with a first type of process interface unit.

13. Operator terminal according to claim 11 or 12, wherein the control unit is further configured to investigate if data values of one type fulfill a similarity criterion or not and form, if said similarity criterion is not fulfilled, a further group including some of the investigated process control values.

14. Operator terminal according to claim 13, wherein the control unit is configured to place data values that fulfill the similarity criterion in one of said at least two groups and to place data values that do not fulfill the similarity criterion in said further group

15. Operator terminal according to claim 13 or 14, wherein the similarity criterion is set as a difference level between the data values of said type and the control unit is configured to place data values of said type in different groups based on if this difference level is reached or not.

16. Operator terminal according to claim 13 or 14, wherein the similarity criterion is set as a threshold and the control unit is configured to compare each value of the type with said threshold and to place data values in different groups based on if they cross said threshold or not.

17. Operator terminal according to any of claims 13 - 16, wherein the control unit is configured to adaptively set the similarity criterion of a group based on the number of measurement values, process interface unit types and already formed groups.

18. Operator terminal according to any of claims 11 - 17, wherein process control data values in at least one group include both real-time measured and historical process control data values.

19. Operator terminal according to any of claims 11 - 18, wherein the control unit is configured to present each group of process control data values in a separate interactive monitoring space (IMS) on the display.

20. Operator terminal according to any of claims 11 - 19, wherein the control unit when fetching data is configured to fetch process control data values from all entities in the system where they are stored.

21. Computer program product on a data carrier comprising computer program code configured to cause said operator terminal to, when said computer program code is loaded into an operator terminal (12) provided in a process control system (10), receive a user selection (Sl, S2, S3, S4) of a number of process control data values being presented on a display, fetch said selected process control data values, form at least two groups (GRl, GR2) of process control data values, where a first group (GRl) only includes process control data values of a first type and a second group (GR2) only includes process control data values of a second type, and graphically present on the display said process control data values in said at least two groups, where the at least two groups are presented separated from each other in order to improve the overview of the process control data.