Variable-voltage generation applied to a.c. power systems

In many parts of the world where the load density is low and major loads and generation are 200¿300 miles apart, voltage control is costly if constant-voltage transmission is used. Such systems are usually radial, and generally considerable development, spread over many years, will have to take place before the interconnections of generating stations result in the familiar grid. Consideration is given in the paper to the effects of using variable-voltage generators on such radial systems. It is shown that if, at times of light load, the generation voltage is reduced to, for example, 90%, and at times of full load it is increased to, for example, 110%, a considerable reduction in synchronous condenser capacity is possible. Such systems are also characterized by small loads tapped off the main transmission, and an example is given of such a system. This shows that, with synchronous condensers at the major terminal load, if the receiver secondary voltage is kept constant and the generation voltage is varied linearly with power, the voltage at the intermediate loads will be reasonable, even if the main load is lost.