Controllable zero sequence current distribution network grounding fault isolating device

Abstract

A controllable zero sequence current distribution network grounding fault isolating device disclosed by the present invention comprises a central station processor (6), a fault point indicator (3) electrically connected with the central station processor (6) and a signal source electrically connected with a bus (ABC). The input end of the central station processor (6) is electrically connected with a secondary side terminal (4) of a bus voltage sensor, and the output end is electrically connected with the control end of a three-phase synchronous operation switch (2) and a control signal terminal (7) of a pole-mounted switch. The signal source spans between a bus terminal (1) and a grounding terminal (8) after the three-phase synchronous operation switch (2) and an impedance grounding transformer (5) are connected in series, and is used to send out a control signal for removing a single-phase grounding fault branch when the bus voltage sensor monitors a single-phase grounding fault and after the central station processor (6) closes the three-phase synchronous operation switch (2) instantaneously. The controllable zero sequence current distribution network grounding fault isolating device has the very high fault point isolation rate, and can be widely used in the single-phase grounding fault isolation field in which a neutral point is not grounded with a power grid system directly.

Description

technical field [0001] The invention relates to a fault isolation device, in particular to a controllable zero-sequence current distribution network grounding fault isolation device. Background technique [0002] In my country's 3-66kV power grid system where the neutral point is not directly grounded, single-phase ground fault is the most common fault. When a single-phase ground fault occurs, it is necessary to find out the faulty branch and deal with it in time, otherwise, it is very easy to cause a large power supply and distribution safety accident. At present, in order to obtain the fault location as soon as possible, people have made various efforts, such as the title "A Distribution Line Fault Automatic Locating System Based on Fault Indicators", "Electric Power Equipment", Volume 6, Issue 10, October 2005 66 - 67 pages of articles. The fault location system mentioned in this article is mainly composed of a large number of fault probes installed on the branch lines ...

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Problems solved by technology

Although this fault location system can locate single-phase ground faults, there are still shortcomings. First, it can only accurately locate low-impedance single-phase ground faults, so the zero-sequence current in the grid system is relatively large , the characteristics of the signal collected by the fault point indicator on the fault branch are obvious—accurate positioning. However, when a single-phase ground fault with medium impedance or high impedance occurs, the zero-sequence current of the grid system itself is very small, and the characteristic quantity is not obvious , resulting in inaccurate positioning; secondly, failure to isolate the fault in time, thereby avoiding further expansion of the accident

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