Fig. 1.1 Michoud steam electric plant, unit number 3 representative list of past cases of such simulation. It is seen from the table that the simulation efforts may be divided roughly into three categories, electronic analog, pneumatic analog, and digital. The pneumatic analog simulator has been the most successful to date in the training of operators to run a thermal-electric generating plant, hi essence this method of simulation has taken actual pneumatic valves and logic elements that would

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... e found on the real system and coupled these to an actual, though scaled down in size, synchronous generator. This generator would normally be driven by a steam turbine but in the simulators it is driven by a direct current motor. While this type of simulator has been very successful, it has the disadvantage that once it is designed and built, it represents one particular thermal-electric generating unit and its characteristics are not easily changed and, in fact, usually are not changed. The effect of the inflexible nature of the system is to allow only operator training for one particular station and no means to study the control problems of a plant before the plant is built. hi order to circumvent the various drawbacks of the "direct analog" simulators, successful attempts have been made to represent the thermalelectric plant with mathematical relationships and to subsequently solve these equations using either electronic-analog or digital computers. These axe listed also in Table 1 .1. The papers of J.