Method for selecting grounding lines on basis of initial current traveling waves and wavelets

Abstract

The invention discloses a method for selecting grounding lines on the basis of initial current traveling waves and wavelets. A novel and reliable method for discriminating the problems in the aspect of selection of single-phase grounding lines for power distribution systems with ineffectively grounded neutral points urgently needs to be created at present. The method includes that amplitude and polarity characteristics of the initial current traveling waves on various loop lines can be represented by modulus maximum values of wavelet transformation, and grounding circuits can be determined according to amplitude and polarity difference of modulus maximum values of the initial current traveling waves of various circuits; traveling wave information in different wave bands can be representedby the modulus maximum values of the wavelet transformation in different scales for power distribution networks with N return outgoing lines on bus when the certain return outgoing lines are subjectedto single-phase grounding, and is used as line selection criteria for single-phase systems, and accordingly line selection results corresponding to the different scales can be obtained. The method has the advantages that the method is based on traveling wave theories, propagation laws and characteristics of transient current traveling waves and traveling wave grounding fault characteristics described by the wavelet transformation used as a tool are utilized, and accordingly the problems in the prior art can be effectively solved by the aid of the method.

Description

technical field [0001] The invention relates to a method for judging the line selection of the grounding line when a single-phase ground fault occurs in a circuit in a power distribution system with neutral point non-effective grounding, specifically a grounding selection method based on initial current traveling waves and wavelets. line method. Background technique [0002] At present, in the power distribution system where the neutral point is not effectively grounded, when a single-phase ground fault occurs in a circuit, the ground current of the power distribution system has only a small capacitive current, and the power distribution system often operates in an unbalanced state. As a result, it is very difficult to use the power frequency to select the grounding line. According to the existing detection methods such as the method of pulling the path, the injection signal method, the steady-state component line selection method, etc., all of which have their own limitati...

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Problems solved by technology

[0002] At present, in the power distribution system where the neutral point is not effectively grounded, when a single-phase ground fault occurs in a circuit, the ground current of the power distribution system has only a small capacitive current, and the power distribution system often operates in an unbalanced state. It is very difficult to select the grounding line by using the power frequency

According to the existing detection methods such as the method of pulling the path, the injection signal method, the steady-state component line selection method, etc., all of which have their own limitations, the line selection results in actual operation are not satisfactory, resulting in grounding The line selection problem has become a technical problem that has plagued the actual operation test for a long time

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