Siemens Aktiengesellschaft

Tevfik Sezi

Andreas Jurisch

Yilmaz Yelgin

Thomas Reck

Matthias Kereit

Gustav Steynberg

Bernd Mitter

Thomas Seidenbecher

Marco Wagner

Gerhard FÜRST

Jörg Blumschein

A method for determining an adjustment value for an electrical protection device wherein, upon occurrence of a ground short circuit, first current indicator measured values and first voltage indicator measured values are captured by a first measurement device at a first end of a segment of an electrical power supply line, and second current indicator measured values and second voltage indicator measured values are captured by a second measurement device at a second end of the segment of an electrical power supply line. In order to design a method of this type such that an adjustment value for a ground impedance can be determined in a relatively simple fashion. A fault location value is determined using the first current and voltage indicator measured values and the second current and voltage indicator measured values, indicating a fault location at which the ground short circuit has occurred in the segment of the electrical power supply line, and an adjustment value indicating a ground impedance is calculated using the fault location value. There is also provided a correspondingly equipped measurement device.

Method for determination of a setting value which indicates a ground impedance, and measurement device

A differential protection system has a differential protection device at each end of a line section of an electrical power transmission line, such that it can selectively identify and safely disconnect even high-impedance faults on the monitored line section. The sensitivity of the system is improved by: detection of current vector measured values which indicate the current flowing in the line section by way of the differential protection devices at the ends of the line section during a learning phase; determination of a correction function from the current vector measured values, the correction function indicating a correction factor which is dependent on the amplitude of the current vector measured values of a selected differential protection device, the correction factor compensating for any amplitude difference and any phase difference between the current vector measured values of the differential protection devices; and adjustment of the differential protection system such that the current vector measured values detected after the learning phase by at least one of the differential protection devices are corrected using the correction function.

Method for increasing the sensitivity of a differential protection system

A method of detecting a fault in a monitored section of an electric line. A release signal and a direction signal are generated, in the event of a fault, by a measuring unit fitted at each end of every section of the line. The direction signal is transmitted via a low-transmission-capacity line from one measuring unit to another measuring unit. Each measuring unit produces, after generating the release signal, intermediate parameters which are suitable for calculating the location of the fault. The intermediate parameters are transmitted via the data-transmission line to the other measuring unit in the section where, in each case, a value is obtained indicating the location of the fault.

Method of detecting a fault in a monitored section of an electric transmission line using distance protection techniques

The present invention relates to a process for determining harmonic oscillations of a fundamental component of an electrical signal, wherein the signal is sampled with a sampling frequency corresponding to a multiple of the fundamental component's frequency. The sampled values of the signal are subjected, after analog-to-digital conversion, to a discrete Fourier transformation to determine the harmonic oscillations. The sampling is performed with a non-integer multiple of the frequency of the fundamental component and the discrete Fourier transformation is performed while the frequency resolution is increased over several periods of the fundamental component to determine the harmonic oscillations.

Process for determining the harmonic oscillations of the fundamental component of an electrical signal

A digital process for determining the effective value of a periodic electric test signal is provided, where the test signal is sampled during a sampling interval that differs in duration from the period of the test signal, and after performing an analog-digital conversion of the samples, they are squared, added up and averaged. The square root of the resulting average is calculated. To be able to determine the effective value rapidly and with a high accuracy according to this invention with a sampling interval that corresponds to two periods of the electric test signal with an odd numbered M of samplings with N samples that fall in one period of the test signal, the values up to and including the Nth sample are squared and added up. To this is added a correction factor that corresponds to half of the square of a subtotal formed from one-quarter of the Nth sample and three-quarters of the (N&plus;1)th sample, where N&equals;(M&minus;1)/2. Then the average is calculated over the number M/2.

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Berlin, Germany

Tevfik Sezi