The frequencies of natural power oscillations in interconnected generating and distribution systems

THE distribution of power in the steady state of interconnected electric networks with large numbers of generators and of consumers of power is well known for a given system. The flow of energy in detail depends on the distribution of the loads, on the admission of power to the prime movers, and on the data for all the connecting lines. With every change of the power distribution in any branch of the system, transient phenomena are initiated which influence the entire complex of prime movers and generators, motors and other consumers, and intermediate lines. As is often observed in the larger systems, the changes in the flow of energy lead to oscillations of power and frequency, depending on the electrical and mechanical data of the generation and the use of the a-c energy. Also we will exclude such very slow fluctuations as may be caused by the control of the steam plant proper or the regulation of the flow of water and which have no direct relation to the electrical part of the system. We shall concentrate our attention on those power oscillations which influence the system frequency and change the distribution of the flow of the active energy within and between the various parts of interconnected systems. These electromechanical fluctuations affect the speed of the generators with their prime movers and speed governors as well as the speed of the numerous motors of the consumers.