Method for searching electric network weakness causing voltage sag

Abstract

The invention provides a method for seeking a weak link of an electric network causing voltage sag, which comprises the following steps: recording voltage sag events and electric network faults; calculating a user voltage sag amplitude expected value and the fault probability of each place; establishing a random analog computation model; performing random analog computation to calculating the user voltage sag amplitude expected value; comparing a computing result and a statistic result; changing fault probabilities of different places, and calculating the voltage sag amplitude expected value; and calculating indexes of the weak link of the electric network, comparing the indexes, and obtaining a result. The method starts from identifying a fault place of the electric network which easily causes the voltage sag events, provides calculation of the indexes of the weak link of the electric network, combines two factors of the fault probability of the electric network and a user voltage sag amplitude caused by the fault, and accurately identifies the fault place of the electric network which easily causes large voltage sag amplitude of the electric network so as to provide priority selection basis for planning and establishment, daily maintenance and technical reformation of the electric network.

Description

technical field [0001] The invention relates to the technical field of power user voltage sags caused by grid faults, in particular to a method for finding places in the grid that are more likely to cause voltage sags due to faults Background technique [0002] The voltage sag (Voltage Sag) problem refers to an event in which the effective value of the supply voltage drops suddenly in a short period of time, and its duration is generally half a cycle to 30 cycles. Although the duration of the event is short, it will cause failures such as equipment downtime and tripping, which will bring huge economic losses to power users. [0003] Several characteristic quantities characterizing voltage sag events are voltage sag amplitude, duration and phase jump. At present, the main quantitative indicator is SARFI(x), which refers to the number of voltage sags with voltage effective value (RMS) below x% in a year, and CEBMA curve and ITIC curve are used to measure the resistance of equ...

AI Technical Summary

Problems solved by technology

The SARFI(x) index only shows the number of voltage sag events, and the CEMBA curve and ITIC curve only show the equipment's resistance to different voltage sag amplitudes and durations, while the critical distance and sag domain are simply based on the grid structure. The possibility of faults occurring at different fault locations is not considered, so it is impossible to really point out the fault locations that have a greater impact on the user's voltage sag problem

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