Method for parallel connection of electric synchronous machines and/or electric 3 phase networks

Abstract

Abstract 1. A method of connecting synchronous electrical machines and/or electrical three-phase networks in parallel by detecting the zero transitions of the two voltages which are to be compared with one another and their mutual phase position in order to form a connect command for power switches, taking into account inherent switching time and the frequency difference DELTA f between the two voltages, characterised in that the current mean of the frequency difference is formed from a plurality of periods of both voltages, that in accordance with a mean value process the respective peak values of the half-cycles are determined over a predetermined number of half-cycles of the two voltages, that for each determined peak value a factor is obtained which permits a "standardisation" of the following instantaneous values in that the factor corrects the measured instantaneous values as if they were obtained from a voltage with a constant peak value of 100%, and that from standardised pairs of instantaneous values of the two voltages points of the envelope curve which enclose the beat curve are determined, whereby harmonic influences in the voltages are substantially eliminated by means value formation and the switching point for the power switch is derived from thus obtained mean values of the frequency difference and the envelope curve.

Inventors

• 👤 Helmut Dipl.-Ing. Leibold

Bibliographic Details