Transient phenomena facts
The power system is one of the most complex systems designed, built, and operated by engineers. In modern society, the power system plays an indispensable role, and a comparable quality of life without a constant and reliable supply of electricity is almost unthinkable.
Because electricity cannot be stored in large quantities, the operation of the power system has the constraint of balancing the production of electricity in the connected power stations and the consumption by the connected loads and of
maintaining constant frequency and constant voltage with the clients.
During normal operation, loads are connected and disconnected. Control actions are therefore continuously necessary – the power system is never in a steady state. On a timescale of years, planning of new power plants, the erection of new transmission lines, or the upgrading from existing lines to higher voltage levels are important items to consider.
Switching actions, either to connect or disconnect loads or to switch off faulted sections after a short-circuit, and disturbances from outside, such as a lightning stroke on or in the vicinity of a high-voltage transmission line, make it necessary to examine the power system on an even smaller timescale, microseconds to milliseconds.
We speak in that case of electrical transients. The time that the electrical transients are present in the system is short, but during a transient period, the components in the system are subjected to high current and high-voltage peaks that can cause considerable damage.
This book deals with electrical transients in the power system. Much has been learned about transient phenomena since the early days of power system operation.