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A Framework for Model-Based Adaptive Training

Power Plant Training Objectives

A training application should be driven by business needs and should cope with multiple training objectives and multiple user profiles. For the prototypical domain in this chapter, a sample set of training objectives has been defined which give a flavour of possible real world objectives. However, the objectives listed in this section do not necessarily constitute real tasks and should not be interpreted as such. The demonstrator centres around a dual purpose subject area embracing:

  • (A) the plant operation; and,
  • (B) the electronic circuit controlling the plant.

The training objectives in this chapter are typical for the specification of any training course, whether delivered by computer based training or other means. Full descriptions for the objectives can be found in [MOBIT 1994, W3]. One of the major problems with the construction of intelligent computer based training systems is the mapping of training task features to (multiple) model attributes. There is a great need for a principled approach to the construction of training systems using (multiple) models, and their validation through practical application. The methods in this chapter are establishing an initial framework by decomposing a practical set of training objectives into a training unit specification for a model-based computer realisation.

Plant Operation Objectives

The first purpose of training is for operators to learn the plant operating procedures. Overall knowledge of the plant process is necessary. As a result of power load demand or other plant constraints such as those imposed by refueling, the operator may be required to alter the load set point using a control panel facia. The operator then needs to ensure that the plant state follows the expected transient behaviour and settles to a predetermined steady state. As a result of abnormal pressure across or flow through, or for servicing, it may be necessary to switch over the feed pumps. In case of pump failure, the operator needs to be able to recover the plant. E.g., by ensuring the standby pump comes on-line, flow, pressures and temperatures return to a steady state and alarm states are avoided. A sticking valve is a common and potentially dangerous problem. Correct operator action on receipt of one or a combination of alarms is required. The operator should follow a pre-defined procedure. In the event of an indication failure, the operator should call on information from plant technicians as necessary. The training objectives that can be derived for plant operators are:

  • (A1) to undertake plant load change;
  • (A2) to accomplish pump switch over;
  • (A3) to recover plant from feed pump trip;
  • (A4) to take appropriate action on receipt of alarm;
  • (A5) to overcome a sticking feed valve problem; and,
  • (A6) to overcome control facia indicator failure.

Circuit Board Repair Objectives

The second purpose of training is for technicians to repair and debug the electronic circuit board which controls the power generating plant. It is assumed that the trainee understands basic logic gates and can read circuit schematic diagrams. The training system steps the trainee through the operation of the circuit and in turn presents a series of boards which do not work. The trainee uses the simulator to identify faults and needs to specify the steps necessary to repair the circuit if repair is possible. Having introduced some custom parts into the circuit a variety of functional faults can be created which can include: no code in the PLD (programmable logic device), wrong code in the PLD, wrong setting on the delay timer switch pack and a variety of typical circuit board problems. The last entry produces shorts and opens which in effect change the circuit on a board thus the actual functionality is different from that on the circuit schematics. The modelling needs to support opens, shorts and nodes tied both high and low. With 4 possible faults applied on any of the nodes, a large number of fault scenarios can be created. The precise number depends on the simulation model [MOBIT 1994]. The training objectives that can be derived for technicians are:

  • (B1) to visually inspect the circuit board;
  • (B2) to recognise the circuit board electronic components;
  • (B3) to debug a circuit board;
  • (B4) to create a set of repair instructions; and,
  • (B5) to repair a defective board.
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