Fluhmann - ABB High Voltage Technologies Ltd Switzerland
Frei - ABB High Voltage Technologies Ltd Switzerland
Hillberg - ABB High Voltage Technologies Ltd Switzerland
Schett - ABB High Voltage Technologies Ltd Switzerland

Considering the aspects that power is in most cases produced close to the resources, but consumed elsewhere, and the ever increasing demand for electrical power, a reliable network where bulk power can be transmitted over long distances, and safely distributed to the consumers, is of utmost importance. Environmental concern and public opinion, which cause resistance against large novel electrical installations, tendencies toward larger interlinked networks, open markets in power supply, in connection with intensifying demands on the reliability of the existing transmission systems, amounts to increased cost pressure on the utilities and a call for optimised solutions and improved concepts for modern substations. The conventional secondary technology for substations consists of a variety of devices, each having a large demand on space and maintenance, and also of extensive process interfaces employing parallel wiring. New substation concepts using digital technology, microprocessor based control with serial communication, and modularised components are superior to previous techniques. Demands on new generation concepts such as increased modularity and compatibility, will not only result in a decreased number of different types of components to be used and kept as spares, but will also further increase the availability and reliability. An advanced Digital Switchgear Control concept is described below, including information on some modern sensors that will contribute to the realisation of this concept. Traditional heavy measurement transformers can be replaced, step by step, by novel, nonconventional, cheaper and integrated sensors. Expensive closing resistors can be pushed away, more and more, by means of soft technologies, such as controlled switching. The digitalisation and use of microprocessors in control and protection of substations have proven, since the introduction in the 70's, to comply with the existent demands on reliability, and are today not associated with any major problem. We advance further in this direction, but with additional requirements on the software function and performance. The higher functionality requests, in order to relieve the inter-level data communication, that control and protection together with other advanced functions should be systematically transferred from the network or substation level down to the bay level, or even integrated into the single apparatus of the switchgear. Such functions as synchronised switching, computer aided supervision, and state dependent maintenance can then be executed by intelligence distributed at the lowest possible level. All control and protection functions will be defined by means of software modules, and will run on the same type of hardware to increase the compatibility. The result will be very flexible station control and protection systems, easy to use and easy to engineer.