10 KV electric transmission line zero-sequence current detection system

Abstract

The invention discloses a 10 KV electric transmission line zero-sequence current detection system. The 10 KV electric transmission line zero-sequence current detection system is characterized in that head ends of auxiliary coils of three load current transformers are connected with a load current detection loop respectively, the tail ends of the auxiliary coils of the three load current transformers are connected with the same point SO, and a zero detection transducer is arranged between the point SO and a signal common end com, wherein the point SO is the head end of a primary coil of the zero detection transducer, and the com end is the tail end of the primary coil of the zero detection transducer. A zero-sequence current sampling resistor Rx is connected to the head end of the auxiliary coil of the zero detection transducer, one end of the resistor Rx is connected to a comprehensive signal processing circuit, the other end of the resistor Rx is connected to the com end, and the tail end of the auxiliary coil of the zero detection transducer is connected to the com end. By means of the 10 KV electric transmission line zero-sequence current detection system, the 10 KV electric transmission line zero-frequency current detection mode in the prior art is changed, micromation and invisibility are achieved, detection accuracy is substantially improved, and false zero-sequence current detection is completely avoided.

Description

technical field [0001] The invention relates to a zero-sequence current detection system for a 10KV transmission line, which belongs to the technical field of 10KV AC high-voltage transmission lines, and belongs to the technical field of power electronics according to the classification specified in "High-tech Fields Supported by the State". Background technique [0002] In 10KV AC transmission lines, in order to detect and eliminate ground faults in time, it is necessary to detect "zero-sequence current" at any time. The so-called "zero-sequence current", in layman's terms, is the leakage current (also called ground current) of the transmission line to the earth. Under the existing technical conditions, a device called "10KV zero-sequence current transformer" is used to detect the zero-sequence current of the 10KV transmission line, and the method of "three-wire parallel penetration" is used to connect the three-phase three-wire 10KV transmission line in parallel. Through ...

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Problems solved by technology

This method is basically feasible, but there are some defects: First, the cost is expensive - there are high requirements in terms of electromagnetic conductivity, high voltage resistance, and harsh environment performance, so the manufacturing cost remains high (the current market The price is between 1500-2500 yuan); the second is that it is large in size and takes up a lot of space, and it is impossible to realize the built-in installation-because three high-voltage transmission lines pass through the through hole of the 10KV zero-sequence current transformer in parallel, so it has to be installed The transformer is made into a larger elliptical ring body (the major axis of the ellipse is between 450-800 mm); the third is that it is prone to mismeasurement-because the span of the three transmission wires passing through the through hole of the transformer is too large, the auxiliary It is difficult to balance the sensitivity of the side coil to the three transmission wires, and it is easy to detect false "zero-sequence current". When the current passing through the transmission line increases, the false "zero-sequence current" also increases. In this case Misjudgments caused by misjudgments are not uncommon

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