Method for inhibiting voltage transformer noise caused by DC magnetic biasing

Abstract

The invention relates to a method of restricting the direct current magnetic bias to generate the noise of the transformer, which belongs to the emergency protection circuit device field. The invention comprises a stopping direct unit and a primary system fault protection unit, the invention is characterized in that two electrolytic capacitances with polarities are connected in series in an inverted polarity way, and a diode is in parallel connected at the both ends of each electrolytic capacitance in a reverted polarity way, so as to form a stopping direct unit; at least more than two diodes are connected in series in sequence in an identical direction way, so as to form an unidirectional overvoltage protection circuit, and two unidirectional overvoltage protection circuits are connected in parallel in a reverse direction way, so as to form a complete primary system fault protective unit. The continuity of the grounding circuit is guaranteed during the changing process of the grounding current at the whole central point from small to large, the complex controlling circuit and the thyristor element are avoided, no risk of the stopping direct component is guaranteed by a built-in auto bypass, the structure parameter of the prior electric network is not changed, and simultaneously, the direct current component can be completely partitioned during the normal operation.

Description

technical field [0001] The invention belongs to the field of emergency protection circuit devices, and in particular relates to an emergency protection circuit device for suppressing a DC current at a neutral point of a transformer. Background technique [0002] With the construction of my country's power grid, more and more direct current transmission lines (also known as high-voltage direct current transmission) have been put into operation, which has played a very active role in the interconnection of regional power systems. [0003] When the DC transmission system operates on a single pole (also known as asymmetric operation), a DC voltage difference will be generated on the ground surface. The same result may also be caused by DC grounding in industrial production (such as DC electrolysis, etc.). [0004] Due to the DC potential difference of the earth, when the transformers at both ends of the transmission line adopt the neutral point grounding method, the DC different...

AI Technical Summary

Problems solved by technology

[0015] The above methods have their own advantages and disadvantages. The first method is simple and feasible, but it is not thorough. The effect is related to the ground potential difference. If the ground potential difference is large and the grounding resistance is restricted by the system and it is not appropriate to increase it, the effect will be poor.

The second method is a more thorough suppression method, but due to the use of control and protection circuits such as the triggering of thyristors, the reliability has decreased, and some uncertain factors

The third method is theoretically feasible, but the actual application is more complicated and difficult to achieve the ideal situation, and the injected DC current brings other problems

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