**Fossil Fuel Power Plant Simulators for Operator Training**

José Tavira-Mondragón, Guillermo Romero-Jiménez and Luis Jiménez-Fraustro *Electric Research Institute Mexico* 

### **1. Introduction**

90 Fossil Fuel and the Environment

Winter, F. & Hofbauer, H. (1997). Temperatures in a Fuel Particle Burning in a Fluidized

*and Flame*, Vol.108, 1997, pp. 302-314, ISSN: 0010-2180

Bed: The effect of Drying, Devolatilisation and Char Combustion, In: *Combustion* 

Before the 1970´s the use of simulators to train the operation personnel of the power plants was not widely diffused. In these times, the operators acquire their skills by working head to head with some experienced operators in the actual plant, so they learned all the knowledge of their mentor, this means, all the virtues and defects of the experienced people. As expected, the trainees also receive the classic classroom lessons with the aim to complement their training. The training finished when the manager of the plant decided the trainee was ready to operate and control the plant. In the majority of the cases, the main problem of this kind of training was that the operator just learned the typical actions related with the start-up of the equipment and operation of the plant in nominal conditions. Therefore, operators had not been trained in abnormal situations, where they needed to act rapidly to keep the power plant in safety conditions. Naturally any operative mistake could lead to a unit trip, equipment damage or risk to staff with all the economic looses related with this type of problems. During the 1970´s, in the United States, the nuclear power industry made the commitment of including simulators as a part of the training programs of their nuclear power plant operators, gradually the use of simulators in the nuclear power industry gained worldwide acceptance. In 1979 a major accident occurred at Three Mile Island (TMI) Unit 2 in Middletown, Pennsylvania resulted in a critical assessment of the preparedness of operations staff to respond to the accident. It is commonly believed that the incident at TMI would not have occurred if the operators had been properly trained. This accident prompted a complete re-evaluation of the nuclear industry's operator training programmes (Perkins, 1985). Events like this reinforced the growth of the rising industry of simulators and that extended its application to the fossil fuel power plants too. Specifically in this segment, the Electric Power Research Institute [EPRI] (1993) carried over a cost-benefit analysis of simulators used at fossil fuel power plants, where the identified benefits were: availability savings, thermal performance savings, component life savings, and environmental compliance savings. Additionally EPRI reported that approximately 20% of forced plant outages were direct result of operator or maintenance error. Therefore, reducing operator controllable outages through training on a simulator can significantly reduce operating costs. Additional quotes about operators errors (Serious Games LLC, 2006), establishes that "One manufacturing analyst estimated, human error leading to abnormal situations costs the UK process industry \$1.4 billion a year" and "In the last 25 years,

Fossil Fuel Power Plant Simulators for Operator Training 93

plant events; a broader range of personnel receiving effective training; and individualized instruction or self-training being performed effectively on simulation devices designed with these capabilities in mind. The use of simulators has proven trough the years to be one of the most effective and confident ways by training power plant operators. Using simulators, operators can learn how to operate the plant more efficiently, lowering the heart rate and

The main features and types of training simulators, the importance of a well structured training programme to maximize the benefits of a simulator and the two most important

According to The Free Dictionary (thefreedictionary, 2008), a simulator is defined as "any device or system that simulates specific conditions or the characteristics of a real process or machine for the purposes of research or operator training". In the context of training of power plant operators, a simulator is a system composed of a Human Machine Interface (HMI) which replicates the operation consoles of the actual plant and a computer that executes mathematical models, which "replicate" unit performance. These simulators are based on the mathematical modelling of dynamic systems and their expected responses have a real-time functioning. Usually the training sessions are guided by an instructor which establishes the initial condition, starts the simulation, and supervises the actions of

According to the training objectives and the available hardware, there are different types of

reducing the power required by plant auxiliary equipment (Hoffman, 1995).

the trainees. This concept is shown in a simplified way in Figure 1.

Fig. 1. Schematic representation of a training simulator.

simulators; a brief review of them is done in the next sections.

**2.1 Simulators with different scopes** 

**2. Training simulators** 

paradigms for the mathematical modelling are discussed in the following sections.

the largest 100 accidents in the hydrocarbon-chemical processing industry cost \$7.52 billion in losses; operator error accounted for 21% of these events at an average of \$75 million per loss".

The modern distributed control systems of the power plants provide to the operator with the elements to get a power generation stable, safe and reliable, but as a consequence, there is a reduction of the operator's confidence to carry out unusual manoeuvres, e.g. a start-up in manual mode or the requested actions after a feed water pump trip. Training simulators help operators to practice this type of manoeuvres. The main advantage of a simulator as a training tool is that the operator does not need to touch the actual unit to learn to operate it in a broad range of possible scenarios. These scenarios include normal operations like unit start-up from cold iron to full load and shutdown. Also can be defined scenarios for malfunctions in which the trainee practice the suitable operative actions when in the simulated unit there are events like: trips of pumps and turbine, tube ruptures, and "faulty" instrumentation. In other words, the operators use the simulator to practice their normal operation procedures and to practice infrequent evolutions and faulted conditions. Therefore, one of the most important parts of the training programmes of power plant operators is carried out trough simulators, a big number of these simulators are of the type called full-scope, these simulators incorporate detailed modelling of those systems of the referenced plant with which the operator interfaces in the actual control room environment. Usually, replica control room operating consoles are included (International Atomic Energy Agency [IAEA], 2004). In these simulators, the responses of the simulated unit are identical in time and indication to the responses received in the actual plant control room under similar conditions. A significant portion of the expense encountered with this type of simulators is the high fidelity simulation software that must be developed to drive it. The completeness of training using a full-scope simulator is obviously much greater than that available on other simulator types since the operator is performing in an environment that is identical to that of the control room. Experienced operators can be effectively retrained on these simulators because the variety of conditions, malfunctions, and situations offered do not cause the operator to become bored with the training or to learn it by rote (Instrument Society of America [ISA], 1993). Therefore, full-scope simulators are recognized worldwide as the only realistic method to provide real-time and hand-on training of operators. Also the simulators can be utilized to validate the normal operating procedures, to conduct engineering studies and to train plant technical supporting personnel.

However, the expense of developing this kind of simulators, the necessity of training a bigger number of the operation staff and the search of better training has driven the development of different training tools, for instance, there are part-task simulators, where the users are only trained in a particular system of the power plant (e.g. feed-water system, steam turbine, etc.). There are also compact simulators, where the users can practice the majority of the main operation actions required in a power plant, but the operation interfaces are of a generic type and not necessarily are similar to the ones the operators utilize in their actual power plant. In many cases, the part-task and compact simulators are portables, so they are transported to the power plants, in this way, the operators can practice onsite, these simulators can be utilized with the assistance of an instructor, in a free-hands context, or with the guidance of an expert system. In spite of the shortcomings of these simulators , there are some clearly identified benefits of using a variety of training simulators, which are: the ability to train on malfunctions, transients and accidents; the reduction of risk to plant equipment and personnel; the ability to train personnel on actual plant events; a broader range of personnel receiving effective training; and individualized instruction or self-training being performed effectively on simulation devices designed with these capabilities in mind. The use of simulators has proven trough the years to be one of the most effective and confident ways by training power plant operators. Using simulators, operators can learn how to operate the plant more efficiently, lowering the heart rate and reducing the power required by plant auxiliary equipment (Hoffman, 1995).

The main features and types of training simulators, the importance of a well structured training programme to maximize the benefits of a simulator and the two most important paradigms for the mathematical modelling are discussed in the following sections.
