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Recent Trends in Power Plant Control
PLENARY PAPERS
Copyright © IFAC Automation and Instrumentation for Power Plants. Bangalore. India. 1986
RECENT TRENDS IN POWER PLANT CONTROL W. Sturmer Ha/'/I//(/I/l1
&
B/'{/I/II
The title of this paper announces statements on the present trend of powe r plant automation. To this end, first of all a glance into the past shall establish the point of departure. 25 years ago the first electrical systems were in operation . The central control room had prevailed for the operation of the main systems. Sequence controls for function groups and data acquisition and monitoring computers were in use 10 years ago. The total system was completed with respect to the sum of compatible subsystems. Today, these complete systems are mostly an integrated system by the respective manufacturer. The path of development of the automation systems was established by the possibilities of electronic technology from the valve to the microprocessor on one hand, and the demands from the development of the processes from conventional boilers up to plants with a modern design on the other hand. The nuclear power plants had a strong effect, especia ll y due to technical safeguard demands. Some impulses into the advanced development of power plant automation are nowadays originated in the area of production automation for process and manufacturing plants (for example MAP). The demands for flexibility and feasibility of integra tion of the systems are predominant in this field of control engineering. With respect to the lead it has been competing with power plant control engineering for years. Let's go back to the modern systems of power plant automation. In addition to the automation system itself, in the present software- oriented systems, there is the extensive documentation whose importance exceeds by far a plant copy. The integrated system is only completed by the inclusion of operators who - as before - take over essential tasks in the operating system of the plant . Earlier, discussions concerning power plant control engineering were held between manufacturers and users; since the time of the nuclear power plants, even intensively with the authorities. Today there is a tension field of opinions and demands which is strongly influenced by the population as the fourth partner and thus influences the power plant development and its control engineering, too. It has become increasingly difficult nowadays to evaluate new control systems according to their advantages and disadvantages. The complexity and scope of the requirements and the systems make a comprehensive and comparative evaluation almost impossible. Just one thing holds true as in all the years passed: the best system is always made by the lecturing supplier, no matter, whether or not the amount of progress or regression is predominant in his system.
AG. FRG
Since - in this case - not an evaluation but a trend is the point of interest, I return to the variable of main influences: the power plants. The dominating plants in the world are conventional coal units and nuclear units up to 800 MW or 1300 MW capacity respectively. Demands for economy and human safety are required of these units, as in the past. In the first demand for economy the availability of the plant, its safety with respect to function, is a decisive factor I F1g. 2 ) as well as the safety of the individual plant units. In the second demand for safety the authorities have always stipulated and monitored the implementation of sufficient precautions to safeguard the lives of the participating people. The decisive change lies in the possible degree of the damage, in the dimension of a catastrophy . Therefrom two necessities or possibilities arise: on the one hand, the need to install sufficient safety features into dangerous processes, on the other hand, to search for new processes with less danger poten tial. An important contribution to the first demand are the automation protection systems. In working out new German standards, a better, more comparative consideration of various risks is discussed. Dependent on it, diff e r e nt requirement classes are mentioned for the protection systems. The proposed risk diagram permits a very clear view of this set of problems. The relatively low damage of a possible injury leads to requirement class O. The possibility of one dead person takes into account the probability of staying in danger zone (A), the risk of several deaths furthermore the possibility of averting danger (B). Accordingly, class 5 is requested for the burner protection in conventional power plants. The possibility of the catastrophy absolutely demands the highest class 7 without contemplating all probabilities, thus for the reactor protection in nuclear power plants. In nature catastrophic damage generally happens slowly by the poisoning of the soil and the atmosphere. The authorities dema~d reliable measuring installations to monitor the degree of pollution. The search for new, less dangerous and more economic al processes today actually leads to combined processes with fluidized bed combustion or integrated coal gasification and - in future plans - to solar power plants with hydrogen technology. New processes and old plants to be subsequently equipped with flue gas purification systems generate new demands (Fig. 3). The available automation systems offer the possibility of the functional and thus economical centralization . When working out the concepts, today - in addition
W. Stunner
2
to the question regarding the degree of automation also the questions with respect to the degree of centralization and degree of redundancy connected therewith must be answered.
additional installation of individual parallelwired controllers, conventional protection systems, conventional manual control stations, conventional indicators and recorders.
The possibility of central processing is generally applied, the one of central transmission up to now only in the area of the electronics and control rooms, not in the field area.
As much as the advantages of the serial systems with their complete action and information access feasabilities via the data highway and the cablesaving marshalling in the control room area catches the eye, the user does not want to dispense with a certain portion of simple, transparent, analog parallel systems, which can be segregated. The lacking single loop integrity is missing in the multiple, i.e. functionally centrally used serial systems. It compensates the lacking availability by redundancies in order to further enter into complexity.
Two examples in the lecture demonstrate how structurally similar initial situations in two power plants to be subsequently equipped with flue gas purification plants lead to different solutions of the concept of operation. If not only the operation but also the construction and reconstruction of power plants is to be contemplated, the complete system in the area of automation expands beyond the actual automation system and documentation system by the planning system or - totally regarded even by the complete engineering system. An elucidation of this thus defined complete system shows the penetration of the serial system into the area of parallel systems (Fig. 4). - The man on the project planning computer thinks now as ever in terms of parallel structures; a thinking pattern structured in parallel develops in his brain. The project planning computer is a digital computer working in series. It requires user software packages for the processing of the alpha-numeric signal names, the symbols and possibly also the positioning and formatting. Man designs the logic of the loops. The documentation system contains function plans and construction diagrams for the realization of the plant. The plans are mainly made up in parallel representation and also partially in quasi-serial representation (lists). - The automation system operates, as far as possible, in parallel on the peripheries towards the process interface, operators' interface and diagnosis
interface . The field area is cabled in parallel.
Only the
automation units operate in serial mode.
The
transfer between the units is executed in parallel or serially. Before this system area is examined more closely, some pictures (during the lecture) from a realized large coal unit are to demonstrate the interaction between documentation and automation.
Two structures are compared by means of drawing in Fig. 5 to discuss the possibilities of signal transmission. The central information and operating system which has been drawn in jointly for both systems generally operates in series, at the interface towards the operator mainly in parallel. The left hand automation system contains only automation units which operate serially in a realistic minimum structure, all signal transmissions are carried out in parallel wiring. In the automation system on the right, also the connections between the automation units operate serially via data highways in a maximum structure which is realistic today. Considerable areas remain in conventional parallel structures in both solutions. Systems, which previously provided for a larger serial area were returned somewhat towards the center of the picture. The market required
Standard modules are mandatory for cost and processing reasons in both structures. In the parallel area these standard solutions (typicals) for manual control loops, measuring loops, protection circuits and possibly control loops, in the serial systems these are user modules for graphic displays, life and heat calculations in the data acquisition and information system, as well as sequence and modulating control modules (e.g. state controllers) in the active systems. The systems of power plant automation worldwide cannot simply be subdivided into digital serial systems and analog parallel systems, all remarkable modern systems contain parallel and serial areas. The optimum will never be in the complete digital system, since the parallel process and man thinking in parallel establish a minimum amount of parallel realization in the periphery. Howev e r, parallel structure and serial processing do not preclude each other. Perhaps the trend towards digital serial systems is going to continue with a decreasing degree of use at lowering prices. A further trend is shown in Fig. 6. The number of automation systems will decrease. The successful manufacturers will have system families whose individual systems are compatible, which will also become compatible in the central area with the systems of other manufacturers, if standardization has continued to advance. This compatibility is provided for parallel systems by the standard levels of the individual signals for many years. The number of automation systems or system families is going to decrease even though the number of the processes is increasing, at least temporarily. The number of documentation systems will also subside in the course of standardization, since a documentation system can represent many automation
systems. The number of all systems would decrease eminently if the nuclear technology would have been a total success (dotted lines). That is not the fact. Therefore there is and will be room for new systems.
Recent Trends in Power Plant Control
Fig. 1
IntegrLltcd coal gasification
SNR
Industry (MAP)
3
Fluidised-bed boiler NO. GilS cleaning
THTR
Desulturisation District heating
LWR
Combined-cycle plant Gas turbine Forced circul. boiler
Drum boiler Users Integrated systems
Populz.lion
Data acquisition Sequence control
Bus
Modulating control
Central control room
le
Measurement and
Transistor
manual control
Valve
Fig. 3
S3tety requirements Economy Size of plant
Complexebility Topogr
Decente Cenlr. Manual ~____~~~
===
Auto L-____
Automation concept Operation concept
Transmission concept Construction
& Function
w. Stunner
4
Automation
Documentation system
syslem
Fig. 4
le F
le le
Fig. 5
Planning system
-j ••• x: C enlr:l lln fo/nI .1 tlo n
and op e ral ing
Humber ot systems
Fig. 6 Processes
Autom. sysl
Docu-systems
~
FI
Fl
p
Copyright © IFAC Automation and Instrumentation for Power Plants. Bangalore. India. 1986
RECENT TRENDS IN POWER PLANT CONTROL W. Sturmer Ha/'/I//(/I/l1
&
B/'{/I/II
The title of this paper announces statements on the present trend of powe r plant automation. To this end, first of all a glance into the past shall establish the point of departure. 25 years ago the first electrical systems were in operation . The central control room had prevailed for the operation of the main systems. Sequence controls for function groups and data acquisition and monitoring computers were in use 10 years ago. The total system was completed with respect to the sum of compatible subsystems. Today, these complete systems are mostly an integrated system by the respective manufacturer. The path of development of the automation systems was established by the possibilities of electronic technology from the valve to the microprocessor on one hand, and the demands from the development of the processes from conventional boilers up to plants with a modern design on the other hand. The nuclear power plants had a strong effect, especia ll y due to technical safeguard demands. Some impulses into the advanced development of power plant automation are nowadays originated in the area of production automation for process and manufacturing plants (for example MAP). The demands for flexibility and feasibility of integra tion of the systems are predominant in this field of control engineering. With respect to the lead it has been competing with power plant control engineering for years. Let's go back to the modern systems of power plant automation. In addition to the automation system itself, in the present software- oriented systems, there is the extensive documentation whose importance exceeds by far a plant copy. The integrated system is only completed by the inclusion of operators who - as before - take over essential tasks in the operating system of the plant . Earlier, discussions concerning power plant control engineering were held between manufacturers and users; since the time of the nuclear power plants, even intensively with the authorities. Today there is a tension field of opinions and demands which is strongly influenced by the population as the fourth partner and thus influences the power plant development and its control engineering, too. It has become increasingly difficult nowadays to evaluate new control systems according to their advantages and disadvantages. The complexity and scope of the requirements and the systems make a comprehensive and comparative evaluation almost impossible. Just one thing holds true as in all the years passed: the best system is always made by the lecturing supplier, no matter, whether or not the amount of progress or regression is predominant in his system.
AG. FRG
Since - in this case - not an evaluation but a trend is the point of interest, I return to the variable of main influences: the power plants. The dominating plants in the world are conventional coal units and nuclear units up to 800 MW or 1300 MW capacity respectively. Demands for economy and human safety are required of these units, as in the past. In the first demand for economy the availability of the plant, its safety with respect to function, is a decisive factor I F1g. 2 ) as well as the safety of the individual plant units. In the second demand for safety the authorities have always stipulated and monitored the implementation of sufficient precautions to safeguard the lives of the participating people. The decisive change lies in the possible degree of the damage, in the dimension of a catastrophy . Therefrom two necessities or possibilities arise: on the one hand, the need to install sufficient safety features into dangerous processes, on the other hand, to search for new processes with less danger poten tial. An important contribution to the first demand are the automation protection systems. In working out new German standards, a better, more comparative consideration of various risks is discussed. Dependent on it, diff e r e nt requirement classes are mentioned for the protection systems. The proposed risk diagram permits a very clear view of this set of problems. The relatively low damage of a possible injury leads to requirement class O. The possibility of one dead person takes into account the probability of staying in danger zone (A), the risk of several deaths furthermore the possibility of averting danger (B). Accordingly, class 5 is requested for the burner protection in conventional power plants. The possibility of the catastrophy absolutely demands the highest class 7 without contemplating all probabilities, thus for the reactor protection in nuclear power plants. In nature catastrophic damage generally happens slowly by the poisoning of the soil and the atmosphere. The authorities dema~d reliable measuring installations to monitor the degree of pollution. The search for new, less dangerous and more economic al processes today actually leads to combined processes with fluidized bed combustion or integrated coal gasification and - in future plans - to solar power plants with hydrogen technology. New processes and old plants to be subsequently equipped with flue gas purification systems generate new demands (Fig. 3). The available automation systems offer the possibility of the functional and thus economical centralization . When working out the concepts, today - in addition
W. Stunner
2
to the question regarding the degree of automation also the questions with respect to the degree of centralization and degree of redundancy connected therewith must be answered.
additional installation of individual parallelwired controllers, conventional protection systems, conventional manual control stations, conventional indicators and recorders.
The possibility of central processing is generally applied, the one of central transmission up to now only in the area of the electronics and control rooms, not in the field area.
As much as the advantages of the serial systems with their complete action and information access feasabilities via the data highway and the cablesaving marshalling in the control room area catches the eye, the user does not want to dispense with a certain portion of simple, transparent, analog parallel systems, which can be segregated. The lacking single loop integrity is missing in the multiple, i.e. functionally centrally used serial systems. It compensates the lacking availability by redundancies in order to further enter into complexity.
Two examples in the lecture demonstrate how structurally similar initial situations in two power plants to be subsequently equipped with flue gas purification plants lead to different solutions of the concept of operation. If not only the operation but also the construction and reconstruction of power plants is to be contemplated, the complete system in the area of automation expands beyond the actual automation system and documentation system by the planning system or - totally regarded even by the complete engineering system. An elucidation of this thus defined complete system shows the penetration of the serial system into the area of parallel systems (Fig. 4). - The man on the project planning computer thinks now as ever in terms of parallel structures; a thinking pattern structured in parallel develops in his brain. The project planning computer is a digital computer working in series. It requires user software packages for the processing of the alpha-numeric signal names, the symbols and possibly also the positioning and formatting. Man designs the logic of the loops. The documentation system contains function plans and construction diagrams for the realization of the plant. The plans are mainly made up in parallel representation and also partially in quasi-serial representation (lists). - The automation system operates, as far as possible, in parallel on the peripheries towards the process interface, operators' interface and diagnosis
interface . The field area is cabled in parallel.
Only the
automation units operate in serial mode.
The
transfer between the units is executed in parallel or serially. Before this system area is examined more closely, some pictures (during the lecture) from a realized large coal unit are to demonstrate the interaction between documentation and automation.
Two structures are compared by means of drawing in Fig. 5 to discuss the possibilities of signal transmission. The central information and operating system which has been drawn in jointly for both systems generally operates in series, at the interface towards the operator mainly in parallel. The left hand automation system contains only automation units which operate serially in a realistic minimum structure, all signal transmissions are carried out in parallel wiring. In the automation system on the right, also the connections between the automation units operate serially via data highways in a maximum structure which is realistic today. Considerable areas remain in conventional parallel structures in both solutions. Systems, which previously provided for a larger serial area were returned somewhat towards the center of the picture. The market required
Standard modules are mandatory for cost and processing reasons in both structures. In the parallel area these standard solutions (typicals) for manual control loops, measuring loops, protection circuits and possibly control loops, in the serial systems these are user modules for graphic displays, life and heat calculations in the data acquisition and information system, as well as sequence and modulating control modules (e.g. state controllers) in the active systems. The systems of power plant automation worldwide cannot simply be subdivided into digital serial systems and analog parallel systems, all remarkable modern systems contain parallel and serial areas. The optimum will never be in the complete digital system, since the parallel process and man thinking in parallel establish a minimum amount of parallel realization in the periphery. Howev e r, parallel structure and serial processing do not preclude each other. Perhaps the trend towards digital serial systems is going to continue with a decreasing degree of use at lowering prices. A further trend is shown in Fig. 6. The number of automation systems will decrease. The successful manufacturers will have system families whose individual systems are compatible, which will also become compatible in the central area with the systems of other manufacturers, if standardization has continued to advance. This compatibility is provided for parallel systems by the standard levels of the individual signals for many years. The number of automation systems or system families is going to decrease even though the number of the processes is increasing, at least temporarily. The number of documentation systems will also subside in the course of standardization, since a documentation system can represent many automation
systems. The number of all systems would decrease eminently if the nuclear technology would have been a total success (dotted lines). That is not the fact. Therefore there is and will be room for new systems.
Recent Trends in Power Plant Control
Fig. 1
IntegrLltcd coal gasification
SNR
Industry (MAP)
3
Fluidised-bed boiler NO. GilS cleaning
THTR
Desulturisation District heating
LWR
Combined-cycle plant Gas turbine Forced circul. boiler
Drum boiler Users Integrated systems
Populz.lion
Data acquisition Sequence control
Bus
Modulating control
Central control room
le
Measurement and
Transistor
manual control
Valve
Fig. 3
S3tety requirements Economy Size of plant
Complexebility Topogr
Decente Cenlr. Manual ~____~~~
===
Auto L-____
Automation concept Operation concept
Transmission concept Construction
& Function
w. Stunner
4
Automation
Documentation system
syslem
Fig. 4
le F
le le
Fig. 5
Planning system
-j ••• x: C enlr:l lln fo/nI .1 tlo n
and op e ral ing
Humber ot systems
Fig. 6 Processes
Autom. sysl
Docu-systems
~
FI
Fl
p