A general hierarchy of control is illustrated in Table 5.1. Manual controls, normally installed adjacent to the device being controlled, are used during testing and maintenance, and as a backup to the automatic control systems. Figure 5.5 illustrates the relationship of control locations and typical functions available at each location. Automatic sequences implemented for starting, synchronizing, and shutdown of hydroelectric units are used.
Modern hydroelectric plants and plants undergoing rehabilitation and life extension are incorporating higher levels of computer automation. The relative simplicity of hydroelectric plant control allows most plants to be operated in an unattended mode from off-site control centers. The current trend is to apply automated condition monitoring systems for hydroelectric plant equipment.
Condition monitoring systems, coupled with expert system computer programs, allow plant owners and operators to more fully utilize the capacity of plant equipment and water resources, make better maintenance and replacement decisions, and maximize the value of installed assets.
