Evaluation method for determining of the probability of an asymmetrical fault location in a distribution network and a monitoring system for performing such method

Evaluation method for determining of the probability of an asymmetrical fault location in a distribution network and a monitoring system for performing such method

Patent

The present invention relates to a method of determining probability of unsymmetrical failure occurrence points in electrical networks, where a backward chart of monitored distribution system is created, a coordination time of a failure occurrence is evaluated based on exceeding a change limit of a current negative phase-sequence component, records of change of a voltage negative phase-sequence component recorded on secondary sides of the distribution transformers (VN/NN) and records of negative phase-sequence components of currents withdrawn from feeding transformers (VVN/VN) are collected for the given coordination time of the failure occurrence. Subsequently, values of maximum change in the current and voltage negative phase-sequence components, corresponding to the instant at which the sum of all the recorded changes in the voltage negative phase-sequence components is maximal are determined. The values of the maximum change in the voltage negative phase-sequence components are converted to the primary side of a corresponding distribution transformer (VN/NN). Individual deviations of absolute values of the calculated changes of the voltage negative phase-sequence component and recorded values of the maximum change in the voltage phase-sequence component at the individual measuring nodes (MU) are then calculated from the converted maximum changes in the voltage phase-sequence components and the current phase-sequence components. Then total deviations of the absolute values of the calculated changes in voltage phase-sequence components and recorded values of the maximum changes in the voltage phase-sequence components for the individual nodes are calculated, and finally, a probability of occurrence of the asymmetry source in individual points of the monitored system is calculated.

The present invention relates to a method of determining probability of unsymmetrical failure occurrence points in electrical networks, where a backward chart of monitored distribution system is created, a coordination time of a failure occurrence is evaluated based on exceeding a change limit of a current negative phase-sequence component, records of change of a voltage negative phase-sequence component recorded on secondary sides of the distribution transformers (VN/NN) and records of negative phase-sequence components of currents withdrawn from feeding transformers (VVN/VN) are collected for the given coordination time of the failure occurrence. Subsequently, values of maximum change in the current and voltage negative phase-sequence components, corresponding to the instant at which the sum of all the recorded changes in the voltage negative phase-sequence components is maximal are determined. The values of the maximum change in the voltage negative phase-sequence components are converted to the primary side of a corresponding distribution transformer (VN/NN). Individual deviations of absolute values of the calculated changes of the voltage negative phase-sequence component and recorded values of the maximum change in the voltage phase-sequence component at the individual measuring nodes (MU) are then calculated from the converted maximum changes in the voltage phase-sequence components and the current phase-sequence components. Then total deviations of the absolute values of the calculated changes in voltage phase-sequence components and recorded values of the maximum changes in the voltage phase-sequence components for the individual nodes are calculated, and finally, a probability of occurrence of the asymmetry source in individual points of the monitored system is calculated.

earth fault, localization, unsymmetrical fault, negative sequence, voltage sag

earth fault, localization, unsymmetrical fault, negative sequence, voltage sag

EP2940483

04.11.2015

05.04.2017

Vysoké ucení technické v Brne Antonínská 548/1 60190 Brno / CZ

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https://register.epo.org/application?number=EP15163595&tab=main

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