| Abstract [eng] |
The main topic of this thesis is the analysis of the accuracy of electrical grid impedance measurement related to electric networks of factories, large commercial and even residential properties. The measurement methods may also have a wider use e.g. in larger distribution networks and stations as well as security systems development and short circuits calculations. When electric systems are being designed the use of theoretical values of resistance for conductors, converters and transitional contacts is common. Same is true for the values of equivalent electromotive. The respective figures are simply inserted into the model of the equivalent short-circuit scheme. This yields the value of the current of the short circuit. In practice and as legally required, short circuit characteristics are measured using certified measurement devices. The latter measure the resistance of an actual electric system, to calculate the short circuit’s current value. In events, when these devices return an intuitively too low values for the current, a concern is caused whether the measurements are feasible: are inductive impedance, transitional electromagnetic processes and the circuit resistance changes in the event of short circuit evaluated etc. This abovementioned problem is approached in this thesis using an analysis of a scheme fragment of an actual electric system, i.e. using a measuring device to determine the resistance of a selected electric circuit, then designing a mathematical model to calculate the short circuit current values with already known electric system parameters inserted. |
