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A simulator is
made up of a group of software programs that are designed to
replicate a power plant. The general types of simulators
are:
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Generic:
The control system, human machine interface and plant
models do not replicate the customers plant. The
accuracy of the modelling is usually less stringent.
However, the generic simulator should model the physics
of the plant faithfully. In practice, a generic
simulator will copy some plant in the world.
-
Full Scope
Replica:
This type of simulator faithfully replicates the control
system, human machine interface and plant. The accuracy
of the models in both the steady state and dynamic
situations will be high.
-
Reduced Scope
Replica:
This will be some compromise between the Generic and the
Full Scope Replica.
Power Station Simulation
A power station
training simulator is a training tool designed to replicate
the steady state and dynamic responses of a power station to
operator actions. In its simplest form, a simulator is a
combination of:
The operator
carries out plant operations on the simulator and observes
responses as they would occur in the real plant. The control
system provides signals to the models and then receives a
signal back from the models as expected.
The difference between Simulation & Emulation
Stimulation
uses the actual hardware and software from the DCS
manufacturer to simulate these features. The DCS hardware is
connected via Ethernet to the process models. In this way
the actual DCS plant software can be tested on the simulator
and later downloaded to the real plant.
The simulator is provided
with a DCS system that is identical to that used in the
actual plant. The simulator both provides and receives
signals from the DCS, this stimulated system allows the DCS
system to operate independently from the simulator with the
simulator operating as a complete plant that is transparent
in operation to the DCS.
Emulation
uses the information for the control system and HMI and
reproduces it in proprietary software of the simulator
vendor.
The simulator has an
emulated DCS system for the Turbine Run-up System. This
system provides the simulator with a Turbine Load that
is able to be controlled and also provide feedback to
the simulator logic.
Models
The models in a
simulator replicate the plant using mathematical techniques.
Some commonly used terms are:
-
Fidelity:
This is the accuracy the models will replicate the
plant. Typical accuracy for a high quality simulator are
1 - 2% steady state and 5 - 20% dynamic;
-
Physical:
This means the modelling equations are based on physical
principles rather than using curve fitting to achieve
the required results. Physical models have a much
broader operating range than curve fitting models.
The standard hardware components of a
simulator
Human Machine Interface (HMI)
The Human Machine Interface is
the screens that the operator will use on the real plant to
control the plant. Generally it is part of the Distributed
Control System (DCS).
Control Logic
Control Logic are algorithms
used to control the plant.
Main Plant control logic is generally part of the DCS,
whereas auxiliary plant controls such as the Turbine run up
system (TRU) will be part of the simulator software.
Instructor Station
The
Instructor software is the brain of the simulator. Its
functions include:
-
Run, freeze, step and
stop the simulator;
-
Apply plant
malfunctions or combinations of malfunctions
(scenarios);
-
Speed-up or slow down
the simulation;
-
Force variables to a
desired value;
-
Prepare and run
training exercises;
-
Access the trainee
databases.
Input/Output (I/O) System
The I/O system
of a simulator is used to drive the hard-panel meters,
gauges and switches.
Main Computing System
The main computing system of a
simulator can be made up of either Intel based PC’s or
microcomputers (e.g. DEC Alpha) and PC’s. It is within the
main computing system that the simulation software resides.
Field Device Terminal
The Field Device Terminal (FDT)
is used to implement (simulator environment) the actions of
manually adjusting a local panel, or particular device.
Maintenance Station
Engineer Maintenance Functions
are those tasks which cover system administration functions.
Turbine Run Up System
Turbine Run Up System (TRU) is
a special control system for the operation and monitoring of
the turbine. The simulator may have separate operating
screens for the TRU or it may be incorporated as part of the
DCS.
DCS Interface
As the DCS (control logic and
HMI) are not produced by the simulator manufacturer (in a
stimulated system) there is a requirement for an interface
between the two systems.
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Functions of a Training Simulator
Training on a Simulator
No matter what
level of training is being carried out in the power station,
training simulators are being used to enhance and improve
the efficiency of this training. Power plants around the
world have discovered that it is much more cost effective to
train competent operators than it is to repair the damage
caused by incompetent ones!
Training in the Basic Principles of Power
Station Operations
New recruits to
power station operations groups, are given training in the
basic principles of power station operations. This training
is usually the pre-requisite for entry into power station
specific operator training courses.
This training
generally covers the logical sequence of power station
operations and the underpinning process knowledge. It
demonstrates what physical conditions exist during plant
operation and the physical effects of changing plant
conditions.
The training of
basic principles can be carried out on a replica or generic
simulator.
Training in DCS Operator Station Layout
Modern power
plants have complex control systems to enhance their
performance. The operators of this plant need to be able to
respond quickly and efficiently. Therefore they must
completely understand the control screen layout. That is,
how to operate the plant, how to access data on the plant
and how to access alarm information.
Training is
carried out to teach new operators how to use the control
screens and to competently perform plant operations, data
review and an alarm review.
This type of
training must be carried out on a replica simulator.
Training in Specific Operating Procedures of
the Plant
Reliable and
safe operation of the plant relies on the operator actions
being carried out following strict operating procedures. By
using procedures, the plant will be operated in a consistent
manner using the "best known way".
Replica
simulators are used to allow trainee operators to practice
plant operations until they are competent in the execution
of plant operations using relevant operating procedures.
Training Operator Response to Plant
Malfunctions and Abnormal Situations.
Effective and
safe operation of the plant requires the operator to respond
quickly and correctly in the event of plant malfunctions or
abnormal conditions. This type of training is generally
provided to experienced operators to enhance their operating
skills or at the end of new operator training.
One of the most
useful features of a simulator is the ability to apply plant
malfunctions. These malfunctions can be grouped and
triggered using predefined conditions using the scenario
function. Using the malfunction and scenario features of a
replica simulator, the operator can be taught how to
identify and respond correctly and efficiently to abnormal
situations. This training requires a simulator that is
accurate in both the dynamic and steady state.
Power Plant Familiarisation
Other staff
within a power station require training in the power station
processes, to enable them to appreciate the business of
Power Generation and the relevance of their duties to the
business. Technicians and maintenance staff benefit from
simulator training as they experience the difficulties of
operating such a complex piece of equipment and develop a
rapport with Plant Operators.
Some utilities
in Australia train their clerical staff on a simulator to
ensure that all staff are fully conversant with the power
generation process.
Conducting Engineering Investigations
A replica
simulator contains mathematical models of the real plant.
Therefore it can be used as a tool for conducting
engineering investigations. The limitation of the utility of
the simulator for this purpose is defined by the boundaries
of the mathematical models and ability of the simulator to
change configuration for either MMI or logic emulation.
Therefore, if the proposed investigation is within the scope
of the mathematical modelling and the configuration can be
changed, then the simulator can be used for this purpose.
Some examples of
engineering investigations are:
-
test plant and/or
control system responses to changed operating
conditions;
-
trial modifications to
plant operating procedures;
-
test control system
changes;
-
test effects on other
plant of plant failures;
-
development of new
plant operating procedures as new plant is added to the
real plant.
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Other Information
The industry
standard for simulators is ISA S77.20 1993
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