Abstract :
This paper describes a new electrical control system with which a standard power-system governor may be made sensitive to system load as well as frequency. A proposed scheme of application is presented which is believed to permit electrical control of a standard governor instead of mechanical control, without any sacrifice of reliability. The frequency of a power system is governed by controlling the power input to the prime movers of the system. Consider, for example, a typical power system in which one hydraulically-driven synchronous generator is governing the system frequency. Since the remaining generating units are operating at constant loads, the power output of the governing unit must be regulated so that the unit will assume any variations of load on the system. Simultaneously, this unit is controlled to hold the system frequency at a constant value. Figure 1 is the schematic representation of a typical governing system of a hydro-electric generating unit. The power output of this unit is regulated by varying the opening of the needle valve to control the flow of water through the turbine This valve is operated by oil pressure through a control valve and piston, as shown in figure 2. The speed-sensitive element in this governing system is a centrifugal governor, driven from the turbine shaft, which operates the control valve by pivoting the beam about point P.
