Method and apparatus for measuring the impedance of an electrical energy supply system

摘要

The invention relates to a method and an apparatus for measuring the impedance of an energy supply system at a rated frequency by impressing a testing current ( 3 ) into the system and measuring ( 4 ) the resulting changes in a system current and a system voltage. According to the invention, the system current and the system voltage are measured during a first preselected time interval (T 1 ) without impressing of the testing current and are measured during a second preselected time interval (T 2 ) with the impressing of the testing current. The testing current is composed of at least one periodic signal with at least one testing frequency (f 1 , f 2 ) that deviates from the rated frequency. Based on the measured system currents and system voltages, a Fourier analysis is used to determine a resulting impedance for the testing frequency (f 1 , f 2 ). The impedance of the energy supply system at the rated frequency is derived from the impedance obtained for the testing frequency (f 1 , f 2 ) (FIG. 1 ).